Chinese Journal of Applied Ecology

A critical review of progresses and perspectives on ecosystem services from 1997 to 2018

GONG Jie, XU Cai-xian, YAN Ling-ling, GUO Qing-hai

2019, 30(10): 3265-3276. doi:10.13287/j.1001-9332.201910.009

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Ecosystem services (ESs) are the research highlight and hot topic in ecology, geography and environmental economics. Based on the literature database on ecosystem services from Web of Science, Citespace, Carrot 2 and textual analysis were used to review the progresses of ESs research during 1997-2018. The results showed that ESs research institutions and its publications increased quickly in the latest 20 years. The main leading countries on ecosystem services research were the United States, UK, Germany, China and Australia, with the United States being the first in terms of literature volume and the influence. Although the research of ESs in China started relatively late, its development was rapid and the scientific research output increased significantly. Meanwhile, there was a huge gap to the international level, the quality and influence of literature should be improved, and the international cooperation and exchange need to be enhanced too. The hotspots and frontiers of ecosystem services mainly included evaluation methods and models, climate change, biodiversity, land use change, trade-off and synergy, scientific research for decision-making and management. The further research and practice trends include the mechanism of ESs, the indicators and methods for ESs evaluation, the spatiotemporal dynamics of ESs trade-offs and synergies and influencing factors, the coupling relationship between ecosystem services and human well-being, and the scientific research and social needs for sustainable development for decision-making and management.

Effects and mechanisms of grazing on key processes of soil nitrogen cycling in grassland: A review

WANG Fang-fang, XU Huan, LI Ting, WU Xing

2019, 30(10): 3277-3284. doi:10.13287/j.1001-9332.201910.021

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Grazing is one of the most important practices for humans to manage grassland ecosystems. The disturbances of feeding, trampling, resting and excreta returning by herbivores will change plant communities and soil nutrient cycling. With the intensification of human activities, the intensity and frequency of grazing were also increased, which would have important impacts on the key processes of soil nitrogen (N) cycling in grassland. Grazing mainly affects the migration and transformation of N in soils by changing soil physical properties, soil N pool size, as well as the composition and structure of soil microbial community. Generally, moderate grazing could enhance soil N mineralization and nitrification, accelerate soil N turnover, and facilitate plant N use. The effects of grazing on denitrification are closely related to the hydrothermal conditions and soil types. Current results on the effects of grazing intensity on various key processes of soil N cycling remain inconsistent, with underlying mechanism being not clear. Based on extensive review of literature, we summarized the research progresses and the underlying mechanisms of the effects of grazing on key processes of soil N cycling. Some deficiencies in current research were pointed out. Possible key topics in the future study were proposed to provide a reference for further understanding the impacts of grazing on soil N cycling in grasslands.

Soil acidification induced by nitrogen addition and its responses to water addition in Inner Mongolia Temperate Steppe, China

GUO Qun

2019, 30(10): 3285-3291. doi:10.13287/j.1001-9332.201910.022

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Soil acidification due to exogenous nitrogen (N) deposition has been received sufficient attention in the past several decades. Whether the N-induced soil acidification is modulated by the altering precipitation regimes remains unclear. In this study, based on a five-year (2013-2017) manipulative field experiment with factorial N addition (10 and 40 g N·m^-2·a^-1 ) and water addition (a total amount of 80 mm·a^-1 was added in terms of five intensities, i.e., 2 mm×40 times, 5 mm×16 times, 10 mm×8 times, 20 mm×4 times, and 40 mm×2 times) in a typical steppe in Inner Mongolia, I analyzed the effects of water addition on soil acidification induced by N addition. I found that soil acidification induced by 40 g N m^-2·a^-1 N addition occurred earlier, more significant, and with a greater year by year changed rate than that of 10 g N·m^-2·a^-1 N addition. After one year treatment, I observed significant soil acidification at soil profiles of 0-5, 5-10, and 10-20 cm in the treatment of 40 g N·m^-2·a^-1 N addition, while significant soil acidification in 10 g N·m^-2·a^-1 N addition was observed after 1, 4, and 5 year since N was added for the three layers, respectively. In general, the magnitude of soil acidification induced by N addition increased with the increasing period after N addition, and the slope of the regression line was steeper in the relatively higher dose of N addition (40 g N·m^-2·a^-1). Soil acidification induced by N addition could not be reversed by water addition, but water addition in terms of relatively lower intensities (i.e., all the treatments except 40 mm×2 times) could relieve the N-induced soil acidification to a certain extent in the treatment with lower dose of N addition (10 g N·m^-2·a^-1) in dry years. In wet years, however, water addition exacerbated soil acidification after N was added, especially in the topsoil. The leaching of soil inorganic N after higher intensity of water addition (10-40 mm) could explain the deteriorated N-induced soil acidification when water was added. There was no significance for the relief or deterioration to N-induced soil acidification by water addition. Our results had important implications for understanding grassland responses to N deposition and altered precipi-tation regime in the future.

Current status of nitrogen and phosphorus losses and related factors in Chinese paddy fields: A review

ZHANG Zi-lu, LIU Feng, HOU Ting-yu

2019, 30(10): 3292-3302. doi:10.13287/j.1001-9332.201910.029

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Rice is one of the main crops in China. Therefore, it is important to understand the current status and influencing factors of nitrogen and phosphorus losses from paddy fields in China, which would facilitate assessing the potential of chemical fertilizer reduction in different rice cultivating regions. We summarized the current knowledge on nitrogen and phosphorus losses from surface runoff in major rice cultivating areas in China, as well as their influencing factors, such as rainfall, planting pattern, cultivation techniques, fertilization management, water management strategies, etc. The total nitrogen (TN) and total phosphorus (TP) losses from runoff in six major rice cropping areas ranged from 5.09 to 21.32 and 0.70 to 3.22 kg·hm^-2, respectively. The highest losses of TN and TP were the South China double rice cropping area. The TN runoff losses were the lowest in the North China single rice cropping area, while the lowest TP runoff losses occurred in plateau single and double rice cropping area of the Southwest China. The peaks of TN and TP in surface water of paddy fields were generally higher than those of the runoff water based on farmers’ conventional fertilization in different rice cropping areas. The peak period of nitrogen and phosphorus losses was in a week after rice fertilization. There could be a potential of 20% reduction of nitrogen and phospho-rus for farmers’ conventional fertilization compared with the optimized fertilization. Among all the factors, rainfall and fertilization management were the main ones affecting the runoff losses of nitrogen and phosphorus in paddy fields. Fertilization management and water management strategies were the mostly controllable, including reduction of fertilizers, application of new fertilizers, replacement of chemical fertilizers by organic fertilizers, water-saving irrigation, etc. Overall, the risk of nitrogen and phosphorus losses in paddy fields was more prominent in the Southern China than in any other areas of China. Rice cultivation should be carried out in a more resource-efficient way to reduce nutrient loss. Future research should focus on non-point source pollution monitoring of paddy fields, nitrogen and phosphorus losses risk assessment, nitrogen and phosphorus losses characteristics and mechanisms, and new technologies for reducing chemical fertilization inputs and environmental risks.

Research progress on relationship between urban greenspace distribution and the socioeconomic characteristics of residents

CAO Ya-qin, CHEN Zhang-hao, HUANG Gan-lin, CHEN Li-yuan, JIANG Ya-qiong, ZHANG Zheng-kai, TU Xing-yue, HUA Ye-yu

2019, 30(10): 3303-3315. doi:10.13287/j.1001-9332.201910.010

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Urban greenspace, which serves as a place for residents to connect with nature and relax, provides important ecosystem services. Access to greenspace is often related to the socio-economic characteristics of residents, which received a lot attention from researchers and practitioners. Previous studies have mostly focused on single city to analyze the spatial relationship between greenspace distribution and residents’ characteristics. We conducted a meta-analysis with global studies. The objectives were to classify findings from different cases and investigate the impacts from the location of research area, indicator and analytical method, and summarized major factors influen-cing the relationship between greenspace distribution and residents’ characteristics. The results showed that more than half of the cases (58.2%) found that the socially advantaged population benefited more from greenspace. About a quarter cases (25.4%) revealed the opposite, that was, the disadvantaged population benefited more from greenspace. The remaining case studies (16.4%) did not find significant correlation between them. The studies reviewed here were diverse in terms of scale, indicator selection, and analytical method. Overall, we found no connection between finding and the choice of scale/indicator/analytical method. The reviewed case studies were mostly conducted in cities of western countries, which differed in their development trajectories and urban characteristics from cities in China. To understand association between urban greenspace and residents’ characteristics in China, we urged to carry out more local studies, which would potentially provide scientific evidence for building sustainable cities during rapid urbanization.

Spatial distribution pattern of Tenebrionidae and its relationships with meteorological factors in Alxa Plateau, China

JIA Long, ZHANG Jian-ying, REN Guo-dong

2019, 30(10): 3316-3326. doi:10.13287/j.1001-9332.201910.038

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We examined the spatial distribution of Tenebrionidae in Alxa Plateau and its environmental response based on the investigation of Tenebrionidae in Alxa Plateau, combined with the temperature, precipitation and solar radiation data, using Grid-Cluster analysis, OriginPro 9.0 and Canoco 5.0 analysis software. The results showed that,with increasing latitude, the number of species rose firstly and declined gradually, with the fitting curve being a parabola. With increasing longitude, the number of species increased gradually, and decreased after the peak, with the fitting curve in approximately unimodal. With increasing altitude, the number of species increased gradually, and decreased after the peak, with the fitting curve showed a single-peak trend. Rainfall, temperature, and solar radiation significantly affected the latitudinal distribution of species richness of Tenebrionidae. Species richness followed a unimodal type with increasing rainfall, peaked in the 38°-39° N. Species richness decreased with increasing temperature and peaked in the 39°-40° N. With the increases of average monthly radiation, Tenebrionidae showed a trend of unimodal type, and peaked at about 16100 kJ·m^-2·d^-1 (38°-39° N). Solar radiation and rainfall were the main meteorological factors affecting the distribution of Tenebrionidae in the Alxa Plateau.

Relationship between tree ring δ¹³C and net primary productivity of Pinus koraiensis in Changbai Mountain, China

DIAO Hao-yu, WANG An-zhi, YUAN Feng-hui, GUAN De-xin, WU Jia-bing

2019, 30(10): 3327-3335. doi:10.13287/j.1001-9332.201910.023

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Carbon isotope in tree ring is an effective indicator of climate and environmental change. However, few studies have analyzed the indication effect of tree ring carbon isotope on net primary productivity (NPP) of forests. Based on meteorological factors of growing seasons, we analyzed the variation trend and the relationship between the tree ring δ¹³C chronosequence of Korean pine (Pinus koraiensis) and net primary productivity (NPP) of Korean pine in Changbai Mountain. We found that before 1970, the change of Korean pine tree ring δ¹³C and NPP was synchronous, with a highly significant linear positive correlation between them, indicating that tree ring δ¹³C recorded the impacts of climate change on NPP. After 1970, tree ring δ¹³C was negatively correlated with NPP but not statistically significant, meaning that other environmental factors such as severe droughts reduced the sensitivity of tree ring δ¹³C to climate change and the recording of NPP by tree ring δ¹³C. The δ¹³C of the current year was also correlated with the corresponding NPP in the following year, which indicated that the current year’s environmental conditions were of great significance to the growth of Korean pine in the following year. This study showed that tree ring δ¹³C was a good indicator of the NPP of Korean pine in Changbai Mountain and that tree ring δ¹³C had the potential to reconstruct long-term changes of forest NPP in the history.

Net carbon exchange and its driving factors of Haloxylon ammodendron plantation in the oasis-desert ecotone of Minqin, China

WU Li-lu, GAO Xiang, CHU Jian-min, WANG He-song, YUAN Qi, DUAN Xiao-feng, GUO Shu-jiang

2019, 30(10): 3336-3346. doi:10.13287/j.1001-9332.201910.018

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Carbon fluxes in a Haloxylon ammodendron plantation in the oasis-desert ecotone of Minqin was measured using an eddy covariance system. To provide scientific data for carbon source/sink assessment, we quantitatively analyzed the characteristics of CO₂ flux and its driving factors in the growing season from May to October, 2018. The results showed that the trend of daily net carbon exchange in the growing season followed a symmetrical “U” shape curve. As to seasonality, bimodal curve was obvious. The plantation ecosystem was a carbon sink every month. The total carbon sequestrated was 34.38 g C·m^-2, with the peak of 12.31 g C·m^-2 in September and the lowest value of 0.89 g C·m^-2 in July. The net carbon exchange in this ecosystem increased during the daytime with the increasing photosynthetically active radiation, consistent with the Michaelis-Menten rectangular hyperbola change. When the vapor pressure deficit was greater than 2.5 kPa, the increasing trend tended to flat. Ecosystem respiration increased exponentially with temperature, with temperature sensitivity being 1.7. Net carbon exchange in either day or night was significantly correlated with soil temperature through the whole growing season.

Effects of thinning on soil active organic carbon contents and enzyme activities in Larix principis-rupprechtii plantation

ZHANG Wen-wen, HAN Hai-rong, CHENG Xiao-qin, SHANG Tian-xiong, WU Ran

2019, 30(10): 3347-3355. doi:10.13287/j.1001-9332.201910.007

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The effects of thinning on soil active organic carbon and related soil enzyme activities were investigated in a Larix principis-rupprechtii plantation in Taiyue Mountain. With the increases of soil depth, the content of soil labile organic carbon, soil nitrogen content and enzyme activities all reduced. For each soil layer, moderate thinning increased soil carbon and nitrogen contents dramati-cally. The activities of sucrase (SC) and peroxidase (PEO) and the activities of polyphenol oxidase (PHO) and urease (UE) in the layer of 0-10 cm could be significantly improved by low thinning and moderate thinning, respectively. For the 10-50 cm layer, the activities of SC and UE were reduced by low thinning, while moderate thinning markedly reduced the activities of cellulase. Results from redundancy analysis showed that dissolved organic carbon (DOC) was the main factor affecting soil enzyme activity in both 0-10 cm and 20-30 cm soil layers and that soil organic carbon (SOC) contents affected the activities of PHO and SC in 10-20 cm soil layer. The microbial biomass nitrogen (MBN) mainly affected the activities of PHO, PEO and UE in 30-40 cm soil layer. The contents of total P (TP) and readily oxidized carbon (ROC) played an important role in affecting soil enzyme activities in 40-50 cm soil layer. The results indicated that thinning could dramati-cally affect soil active organic carbon content and soil enzyme activity in L. principis-rupprechtii plantation. Moderate thinning treatment could obtain the highest soil nutrients and achieve better soil chemical properties such as soil pH, water content and organic matter content than other treatments, which could improve vegetation structure, litter and nutrient cycling process. Therefore, we recommended moderate density adjustment (1404-1422 trees·hm^-2) to L. principis-rupprechtii plantation to promote soil carbon and nitrogen retention.

Seedlings regenerative dynamics of dominant trees in a secondary forest in montane region of eastern Liaoning Province, China

CAI Jun-qi, WANG Pin, LIU Da-peng, BAI Xue-jiao, ZHANG Shu-yuan, ZONG Guo, LIU Jia

2019, 30(10): 3356-3366. doi:10.13287/j.1001-9332.201910.005

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To reveal the seedlings dynamics of dominant trees and their response to canopy changes (as indicated by changes in leaf area index), we analyzed the seedlings dynamics of dominant trees and canopy structure during forest regeneration based on three-year (2014 to 2016) censuses and hemispherical photography in a 4 hm² forest dynamics monitoring plot. The results showed that canopy LAI first decreased and then increased during the survey period, with significant interannual difference. The seedlings of 12 dominant tree species showed notable response to the change of canopy structure, with the response varying among different tree species. The relative abundance or frequency of seedlings for neutral tree species generally increased with the decreases of canopy LAI. The relative abundance or frequency of seedlings of light-demanding tree species generally decreased with the increases of canopy LAI. In multi-response permutation procedures by analyzing the numeric composition and distribution of dominant tree seedlings, there was significant difference among the three censuses. Such interannual difference gradually decreased from 2014 to 2016. Significant change occurred in the indicator species of dominant tree seedlings, reflecting their responses to the changes of canopy structure.

Effects of long-term rainfall addition on the morphological characteristics and point pattern of desert plants

ZHANG Jing-bo, LI Xin-le, WU Bo, LIU Ming-hu, LI Yong-hua, XIN Zhi-ming, DONG Xue, DUAN Rui-bing

2019, 30(10): 3367-3375. doi:10.13287/j.1001-9332.201910.013

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Studying the effects of rainfall change on morphological characteristics, spatial pattern and spatial correlation of desert dominant plants could help to predict the response of desert ecosystem to global climate change. We conducted a 10-year simulated rainfall addition experiment and examined the morphological characteristics, spatial pattern and spatial correlation of typical desert plant species, Nitraria tangutorum and Artemisia ordosica, under long-term simulated rainfall enhancement conditions in Ulanbuh desert, using Programita software, Ripley’s K function, and Monte Carlo method. The results showed that there were significant differences in the number, height, average crown and base diameter of the desert plants under different treatments. The number, height, average crown and base diameter of N. tangutorum and A. ordosica were significantly larger than CK, all of which increased with the amount of rainfall. When the amount of rainfall addition was less than 72 mm, the branch of N. tangutorum showed cluster distribution. When it was larger than 72 mm, it showed a tendency to decrease the aggregation intensity with rainfall increasing. The spatial distribution of A. ordosica population was characterized by random distribution-cluster distribution-random distribution pattern with rainfall increasing. In terms of spatial association, branch of N. tangutorum and A. ordosica showed negative correlation under control, but no correlation or positive correlation with rainfall increasing. When the amount of rainfall increased to 144 mm, the spatial association between two species changed from negative to positive. Under the scenario of increasing rainfall, soil moisture was improved, which would lead to a positive correlation between species and be more conducive to the coexistence and growth of N. tangutorum and A. ordosica.

Effects of salt stress on growth, photosynthetic and fluorescence characteristics, and root architecture of Corylus heterophylla ×C. avellan seedlings

LUO Da, SHI Yan-jiang, SONG Feng-hui, LI Jia-cheng

2019, 30(10): 3376-3384. doi:10.13287/j.1001-9332.201910.001

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We examined the effects of different salt stress intensities (control, mild, moderate, severe) on the growth traits, photosynthetic and fluorescence characteristics, and root architecture of three Corylus heterophylla × C. avellan varieties (Xinzhen 1, Xinzhen 2, Xinzhen 3). The results showed that the new shoot length, basal diameter, leaf area, root biomass, shoot biomass, leaf biomass, and total biomass of the three varieties all decreased, but the root-shoot ratio increased with increasing salt stress. The net photosynthetic rate of the three varieties in the moderate and severe salt stress treatments significantly decreased by 20.5% and 43.2%, respectively. The transpiration rate and stomatal conductance in the mild, moderate, and severe salt stress treatments decreased by 2.0%, 16.3%, 32.0% and 10.2%, 35.7%, 60.1% than those of the control, respectively. With the increasing salt stress, the intercellular CO₂ concentration gradually increased, while the water use efficiency increased first and then decreased and being the highest in the mild salt stress treatment. The initial fluorescence of the three varieties increased with the increasing salt stress. With the increasing salt stress, the maximum fluorescence, maximal photochemical efficiency, potential photochemical activity, actual photochemical efficiency, electron transfer rate and photochemical quenching coefficient decreased, while the non-photochemical quenching coefficient increased first and then decreased. Salt stress reduced root biomass, length, surface area and volume of the three varieties. In the same salt stress treatment, the reduction of root architecture parameters of Xinzhen 2 was lower than the other two varieties. The growth traits, photosynthetic and fluorescence characteristics, and root architecture parameters of Corylus heterophylla × C. avellan were affected by both varieties and salt stress. Xinzhen 2 displayed stronger growth and photosynthetic physiological adaptability to salt stress, showing stronger salt tolerance than the other two varieties.

Estimation of forest vegetation carbon storage in Hunan Province, China based on k-NN method and domestic high-resolution data

ZHANG Qin-yu, WANG Hai-bin, PENG Dao-li, XIA Chao-zong, CHEN Jian, LIU Wen-jie

2019, 30(10): 3385-3394. doi:10.13287/j.1001-9332.201910.016

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To promote the application of domestic high-resolution satellite data in large-scale carbon storage estimation and measurement, a total of 206 high-resolution remote sensing images covering Hunan Province were used as the data source, and the estimated minimum unit was fixed as a 0.06 hm² square composed of multiple pixels. Through the establishment and purification of the interpretation marks, in the extraction of forest information, the pixel-based method and object-oriented classification method were used to compare. In the estimation of carbon storage of arbor forest, the robust estimate, partial least squares method and k-NN estimate were used to compare. Finally, we estimated forest carbon storage in Hunan Province and generated the distribution map of carbon density levels. The results showed that the interpretation mark based on the automatic extraction of plots could increase the extraction accuracy of arbor forest after purification. For the estimation of forest carbon storage at large-scale, the k-NN algorithm embodied a large advantage in forest information extraction and arbor forest carbon storage modeling. The average classification accuracy of the 206 scene images was 76.8%, the average RMSE was 8.95 t·hm^-2, the average RRMSE was 19.1%, and the total carbon stock in Hunan Province was 22.28 Mt. The results provided effective reference for the estimation and measurement of forest carbon storage at the provincial and national scales.

Flora and geographic pattern of mountain forests at community level in Taihang Mountains: Results based on plant community survey

ZHANG Yin-bo, MENG Qing-xin, QIN Hao, TANG Zhi-yao, ZHANG Feng

2019, 30(10): 3395-3402. doi:10.13287/j.1001-9332.201910.031

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Taihang Mountains is located on the eastern edge of the second step of Chinese topography, which is the natural boundary between Loess Plateau and North China Plain and is considered as one of the important priority areas for biodiversity conservation in China. We took 108 counties involved in the generalized Taihang Mountains as the research area to systematically analyze the characteristics of family and genus characters, floristic composition, geographical pattern of plant diversity and species richness hotspots at community level of mountain forests in Taihang Mountains. A total of 963 species of seed plants belonging to 447 genera and 100 families were recorded in 778 forest plots in Taihang Mountains. Within all the species, 12 species of gymnosperms belonging to 7 genera of 3 families, 951 species of angiosperms belonging to 440 genera of 97 families. Herbaceous plants (71.1%) was the dominant life form. The distribution types of families were mainly tropical (38%) and temperate (24%), and the distribution types of genera were mainly temperate (68.7%). The horizontal distribution pattern of plant diversity showed a trend of increasing from southwest to northeast. Species richness was positively correlated with the latitude and longitude. However, the richness patterns of different life-form plants were different, in that herbaceous richness was positively correlated with the longitude and latitude but that of woody plants was not. In the vertical gradient, plant richness of Taihang Mountains presented a single-peak distribution, which was concentrated in the low and middle elevations of 400-1800 m and peaked at 1000-1200 m. Based on the community inventory data, we mapped plant richness of Taihang Mountain forest community. The mountain areas such as Xiaowutai Mountain, Yuntai Mountain, Taiyue Mountain, Wangwu Mountain and Zhongtiao Mountain were identified as hotspots of plant richness, which should be included in the key planning and management areas of the Taihang Mountains priority protection.

Effects of socioeconomic factors on urban plant diversity of residential areas in Shanghai, China

HUANG Yue, CHEN Yu, HE Yu-juan, WANG Meng, KUANG Sheng-jian, CHEN Guo-jian, LI Jun-xiang

2019, 30(10): 3403-3410. doi:10.13287/j.1001-9332.201910.033

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Residential area, usually consisting of buildings and vegetation, is one of the dominant land use types and an important kind of habitat in the urban area. Therefore, it plays an important role in urban biodiversity conservation. Previous studies found that plant diversity abroad in urban residential areas was influenced by socioeconomic factors. However, it is not clear whether this result hold for Chinese cities which have completely different urban management regime. In this study, we investigated plant species diversity in 39 residential neighborhoods in Shanghai. Biodiversity indexes, regression analysis, and partial least square regression analysis were employed to estimate the relationships between plant diversity and socioeconomic factors of population density, house price, house age and greenspace coverage. Our results showed that socioeconomic factors did affect plant diversity in urban residential areas in Shanghai. The effects varied with plant species, population density, house price, house age, and greenspace coverage. The house age had the strongest effect on most plant taxa, then followed by population density, house price, and greenspace coverage. We tested the hypotheses of “luxury effect” and “legacy effect”, and found that they only partially explained the spatial distribution of plant taxa in Shanghai. These results could provide insights for management and conservation of plant diversity, as well as urban landscape planning and design in Shanghai.

Fungal diversity in the brown coniferous forest soils of Daxing’anling Mountains, Northeast China

YANG Li-bin, SUI Xin, WEI Dan, CUI Fu-xing, ZHU Dao-guang, NI Hong-wei

2019, 30(10): 3411-3418. doi:10.13287/j.1001-9332.201910.030

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To explore the distribution of fungal community in soil of brown coniferous forest in Daxing’anling and its relationship with soil characteristics, soil fungal community structure and diversity in three forest types, light brown coniferous forest, grass brown coniferous forest, and typical brown coniferous forest, were analyzed by high-throughput sequencing technology. The relationship between soil fungal community and soil characteristics was analyzed by R and SPSS 17.0 software. The results showed that soil physical and chemical characteristics differed significantly across the three brown coniferous forests. A total of 111 species belonged to six phyla, 23 class, 46 orders, 74 families and 88 genera were recorded in this study. Ascomycetes and basidiomycetes were dominant phyla. There were significant differences in relative abundance of phyla among three forest types. There was no significant difference in the Ace and Chao1 diversity indices among three brown coniferous forests, whereas there were significant differences in the Shannon and Simpson indices. Results from canonical correlation analysis and correlation analysis showed that both α and β diversity were significantly correlated with soil moisture, soil pH, soil organic matter, soil total nitrogen, and soil total potassium. The results indicated that soil characteristics were important factors affecting soil fungal diversity of brown coniferous forest in Xing’an larch forest in Daxing’anling.

Impacts of climate change on the distribution of Cymbidium kanran and the simulation of distribution pattern

CHEN Yan-ru, XIE Hui-min, LUO Huo-lin, YANG Bo-yun, XIONG Dong-jin

2019, 30(10): 3419-3425. doi:10.13287/j.1001-9332.201910.011

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In this study, data of 19 climatic factors were downloaded from the World Climate website. A total of 233 Cymbidium kanran distribution data were obtained through online review and field visits. Using MaxEnt model and combined with ArcGIS spatial analysis technology, the potential distribution area and distribution pattern of C. kanran in different periods were simulated, as well as its distribution during the last glacial period and 2070. The results showed that the curve indexes (AUC) value of the model training set was 0.957, and the AUC value of the verification set was 0.953, indicating that the prediction accuracy of the model was very high. The current distribution of C. kanran was mostly affected by the driest quarter precipitation, mean annual precipitation, wettest quarter precipitation, and mean annual temperature range. The contribution rates were 50.3%, 15.9%, 8.4% and 4.4%, respectively, with the total contribution rate being 79.0%. In the last glacial period, C. kanran mainly distributed in Wuyi Mountain, Luojing Mountain, Nanling, Taiwan’s five major mountains and some hills in the northern part of Guangxi. From now to 2070, the distribution of C. kanran area will decrease by 22.4%. The southwestern part of Guangxi, the central part of Yunnan, and the junctions of Jiangxi, Fujian and Guangdong provinces will expand, while that in eastern Jiangxi, western Fujian, and the border between these two provinces will shrink.

Responses of water consumption characteristics and grain yield of maize to different nitrogen form ratios with full film mulching on double ridges and planting in furrows

CUI Zheng-jun, GUO Li-zhuo, GAO Yu-hong, LI Chun-chun, PENG Zhi-dong, LIU Hong-sheng, NIU Jun-yi

2019, 30(10): 3426-3434. doi:10.13287/j.1001-9332.201910.025

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To optimize the effects of nitrate (NO₃^--N) to ammonium (NH₄⁺-N) ratios on water consumption characteristics, grain yield and water use efficiency (WUE) of maize under full film mulching on double ridges, a field experiment was conducted at semi-arid Loess Plateau of Gansu Province, China during 2015 to 2017 cropping seasons. The treatments with different ratios of NO₃^--N to NH₄⁺-N included: N₁ (1:0), N₂ (1:1), N₃ (1:3) and N₄ (3:1). The results showed that different NO₃^--N/NH₄⁺-N ratios had significant impacts on soil water storage in 0-200 cm soil layer. Treatment N₃ had the lowest soil water storage. Treatment N₄ significantly increased total water consumption by 2.9%, 1.9% and 0.9% in 2015, and 2.3%, 1.4%, and 2.2% in 2017, compared with N₁, N₂ and N₃ treatments, respectively. Compared with the other treatments, treatment N₄ increased grain yield by 3.3%-9.9%, 3.5%-24.2% and 8.3%-36.1% and improved WUE by 1.6%-6.8%, 4.9%-21.8%, and 6.6%-32.9% in 2015, 2016 and 2017, respectively. Treatment N₄ had the highest partial productivity of nitrogen fertilizer, followed by N₂, N₃ and N₁, respectively. We recommended treatment N₄ as the best nitrate and ammonium ratio to improve water use efficiency, N partial productivity, and grain yield of maize in arid and semi-arid Loess Plateau.

Effects of soil structure improvement on chlorophyll fluorescence parameters and yield of rice in a coastal reclamation region

A LIMU·A-Bu-lai-ti, YAO Huai-zhu, SONG Yun-fei, FEI Yuan-hang, SHE Dong-li

2019, 30(10): 3435-3442. doi:10.13287/j.1001-9332.201910.026

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To examine the effects of soil structure improvement due to the amendment of biochar and polyacrylamide (PAM) on the chlorophyll fluorescence characteristics of rice leaves and the yield of rice, a pit cultivation experiment was carried out in a coastal reclamation region. Three levels of biochar (0%, 2% and 5% by the mass of 0-20 cm surface soil and noted as B₁, B₂ and B₃, respectively) and PAM (0‰, 0.4‰ and 1‰ by the mass of 0-20 cm surface soil and noted as P_1,P₂ and P₃, respectively) were applied to the adopted soil, respectively. The results of the three-year experiment showed that an appropriate application quantity of biochar and PAM could improve the fluorescence characteristics of rice leaves. However, high levels of biochar and PAM had no obvious or even a negative effect. Among all the treatments, the B₂P₂ treatment always had the highest the maximum photochemical efficiency (F_v/F_m), the actual photochemical efficiency of photosystem II (Φ_PSⅡ), the photochemical quenching coefficient (q_P) and the non-photochemical quenching coefficient (NPQ) values during the whole growth period. The chlorophyll content (SPAD value) of rice leaves showed no significant difference among different biochar application levels. However, it showed significant differences among different PAM application levels, with the highest value under the soil amended with 0.4‰ PAM (the P₂ treatment). The application of biochar and PAM had significant impacts on rice yield, with the highest yield, namely 7236 kg·hm^-2, presenting under the B₂P₂ treatment, which was 28.5% higher than that of the control. The improved soil structure of the coastal saline soil due to the amendment of biochar and PAM affects rice yield mainly through its influences on the 1000-grain weight, the spike number per hole, the grain number per spike and the seed setting rate. It is concluded that improving soil structure by applying an appropriate quantity of biochar and PAM is conducive to increase the chlorophyll fluorescence characteristics and the yield of rice in the coastal reclamation region.

Effects of sowing date and seeding rate on soil water consumption and plant nitrogen translocation in dryland wheat

TIAN Xin, SUN Min, GAO Zhi-qiang, ZHANG Juan, LIN Wen, XUE Jian-fu, YANG Zhen-ping, MO Fei

2019, 30(10): 3443-3451. doi:10.13287/j.1001-9332.201910.028

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To tackle the issue of rainfall delay during dryland wheat sowing season and further examine the effects of seeding rate on water use and yield formation, a field experiment was conducted at Wenxi Experimental Station, Shanxi Province between 2015 and 2017. We used two sowing dates, i.e. September 20 and October 10 as early (EB) and late (LB) sowing in main plots, and each with three seeding rates as 67.5 (LD), 90 (MD) and 112.5(HD) kg·hm^-2. The results showed that compared with LB, EB increased total soil water consumption by 11-22 mm over the entire growing season. With the increases of seeding density, total soil water consumption increased by 2-20 mm. Soil water consumption before anthesis tended to increase for LB, while there was a significant increase of soil water consumption after anthesis for EB. Compared with LB, the pre-anthesis nitrogen translocation and post-anthesis nitrogen accumulation amount in EB were increased under LD and MD, but decreased under HD. For EB, the pre-anthesis nitrogen translocation amount and post-anthesis nitrogen accumulation amount were highest at LD. Under LB, the pre-anthesis nitrogen translocation amount and post-anthesis nitrogen accumulation amount were greatest at high sowing density. EB significantly increased grain yield by 163-996 kg·hm^-2 than LB. EB significantly increased grain yield and water use efficiency by 5%-26% and 2%-21% compared with LB, respectively. The nitrogen absorption efficiency and harvest index were 3%-36% and 11% higher under LB than that under EB. As for seeding rate, a low level tended to gain higher grain yield, water use efficiency, nitrogen uptake efficiency and nitrogen harvest index under EB, whereas a high level tended to gain higher values of grain yield, water use efficiency, nitrogen uptake efficiency and nitrogen harvest index under LB. In addition, the pre-anthesis nitrogen translocation was closely related with 100-200 cm soil water consumption before anthesis, especially for stem + sheath, glume + spike nitrogen translocation. The post-anthesis nitrogen accumulation was significantly correlated with 100-300 cm soil water consumption after anthesis. In conclusion, early sowing with a seeding rate of 67.5 kg·hm^-2 and late sowing with a seeding rate of 112.5 kg·hm^-2 could be promising options to boost dryland wheat production.

Effects of intercropping on light energy utilization characteristics and productivity of diffe-rent feed crops

LIN Fang, LIU Xiao-jing, TONG Chang-chun, WU Yong

2019, 30(10): 3452-3462. doi:10.13287/j.1001-9332.201910.006

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To explore light energy utilization characteristics and yield effect of different legume-gramineae intercropping patterns, we set up five kinds of monocropping patterns including alfalfa, triticale, oats, maize and sorgo as reference in a field experiment. The light energy utilization chara-cteristics and productivity of four kinds of intercropping patterns including alfalfa-triticale, alfalfa-oats, alfalfa-maize and alfalfa-sorgo were examined. The contribution degree of each light energy index to yield formation was analzyed using path analysis method. The results showed that the contribution of each index of light energy to yield from large to small was as follows: leaf area index (LAI)=1.236, net photosynthetic rate (P_n)=0.519, canopy openness (DIFN)=0.302, intercellular CO₂ concentration (C_i)=-0.026, stomatal conductance (g_s)=-0.116, transpiration rate (T_r)=-0.188, PAR interception rate (FIPAR)=-1.708. Light use efficiency (LUE) as a comprehensive indicator of light energy utilization had the largest value (1.367). Compared with monoculture, the values of LAI, P_n, g_s, T_r and FIPAR of four kinds of gramineae grasses increased under intercropping and the values of DIFN and C_i decreased, while alfalfa showed an opposite trend. Compared with monoculture, the LUE of four kinds of gramineae grasses under intercropping was significantly increased. The increase rates of triticale and oats (35.2% and 30.4%) were higher than that of maize and sorgo (28.7% and 26.3%). The decrease rates of alfalfa intercropping with triticale and oats (6.1% and 8.3%) were obviously lower than that of maize and sorgo (21.8% and 24.5%). The values of land equivalent ratio (LER) of four kinds of intercropping patterns was all greater than 1. The LER values of alfalfa-triticale and alfalfa-oat were significantly higher than those of alfalfa-maize and alfalfa-sorgo. It could be seen that LAI had the largest direct contribution to yield, followed by P_n. Among the four intercropping patterns, two patterns, alfalfa-triticale and alfalfa-oats, had greater improvement potential of light energy utilization and yield.

Effects of tillage types on soil aggregate distribution and stability in irrigated sierozem of Gansu Yellow River irrigation area, China

HUO Lin, YANG Si-cun, WANG Cheng-bao, JIANG Wan-li, WEN Mei-juan

2019, 30(10): 3463-3472. doi:10.13287/j.1001-9332.201910.027

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A total of six treatments, including continuous conventional tillage (CT), rotary tillage (RT), subsoiling (ST), no-tillage (NT), conventional-no tillage (CT-NT) and subsoiling-no tillage (ST-NT), were conducted to examine the effects of different tillage types on soil aggregates distribution and stability of irrigated sierozem on continuous 8-year-tillage maize fields in the Gansu Yellow River irrigated area in 2014-2017. The results showed that the aggregation and stability of large aggregates in 0-40 cm soil layer were increased by NT and ST-NT treatments, while the size distribution and stability in plough layer were significantly decreased by CT and RT treatments due to strong soil disturbance. Compared with RT, the mechanical stability of aggregates under dry sieving NT was the best. The contents of >0.25 mm aggregate (R_0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 5.8%, 8.0%, and 13.0%, respectively, and fractal dimension (D) decreased by 3.6%. The water-stable aggregates in ST-NT was the best, with R_0.25, MWD and GMD increased by 55.3%, 15.1% and 8.7%, respectively, and D value decreased by 0.8%. The percentage of aggregate destruction (PAD) and unstable aggregate index (E_LT) of NT and ST-NT treatments were the lowest. PAD was reduced by 5.9% and 7.7% compared with RT, E_LT was reduced by 5.8% and 7.2%, respectively. All the results indicated that the subsoiling-notillage (ST-NT) rotation mode was more conducive to the enhancement of soil aggregate content and stability and consistent with the local farmers operating habits, which would be an ideal tillage method and had certain application value for the sustainable agricultural development in this area.

Effects of grazing exclusion on the abundance of functional genes involved in soil nitrogen cycling and nitrogen storage in semiarid grassland

LIAO Li-rong, WANG Jie, ZHANG Chao, LIU Guo-bin, SONG Zi-lin

2019, 30(10): 3473-3481. doi:10.13287/j.1001-9332.201910.002

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We investigated the effects of grazing exclusion on the abundance of functional genes (nifH, amoA-AOA, amoA-AOB, narG, nirK, nirS, and nosZ) involved in soil nitrogen cycling in soil profiles (0-10, 10-20, 20-40 and 40-60 cm) from a chronosequence of grazing exclusion (0, 7, 18, 27 and 35 years) in the semiarid grasslands of the Loess Plateau. The relationship between abundance of functional genes and soil nitrogen storage was evaluated. The results showed that 35 years exclusion increased the abundance of nifH and amoA-AOB genes by 67.8% and 17.6% compared with the grazed grassland, respectively, and decreased that of nirK genes. The abundance of nifH, narG, and nirS genes in surface soil (0-10 cm) were significantly higher than that in deep soil (20-40 and 40-60 cm), indicating that those genes had surface accumulation effects. Grazing exclusion increased soil nitrogen storage. Soil nitrogen storage in 0-60 cm layer was the highest at 27 years (20.96 mg·hm^-2), indicating that 27 years might be the optimum for grazing exclusion. The abundance of nifH, amoA-AOA and amoA-AOB had a significant linear relationship with nitrogen storage, suggesting that microbes harboring these genes played an important role in soil nitrogen accumulation. Total nitrogen, bulk density, and available phosphorus content were the dominant factors affecting the abundance of functional genes involved in soil nitrogen cycling. Our results provided a scientific reference for understanding soil nitrogen cycling and restoration of degraded grassland.

Effects of different grasses cultivation on apple orchard soil microbial community

JIANG Li-li, GONG Qing-tao, WU Hai-bin, SHENG Fu-jing, SUN Rui-hong

2019, 30(10): 3482-3490. doi:10.13287/j.1001-9332.201910.039

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Taking naturally growing grass (NG) as comparison, high-throughput sequencing technique was adopted to examine the effects of Lolium perenne (LP), Trifolium repens (TR), Vulpia myuros (VM), and Vicia villosa (VV) cultivation on soil microbial community in apple orchard of Yanggu County, Shandong Province, and the correlations of soil microbial community with soil nutrient and physicochemical property. The results showed that LP increased the relative abundance of Alternaria and Aspergillus in soil, TR increased that of Gibberella, VM increased Aureobasidium and Chaetomium, and VV increased probiotics such as Nitrososophaera and Metarhizium. However, the quantity of pathogenic bacteria Ralstonia was improved in NG treatment. Results from Spearman correlation analysis showed that the abundance of Bacillus was significantly positively correlated with the concentration of soil organic matter. The abundance of Aspergillus was significantly negatively correlated with available phosphorus, available potassium, CEC, and organic matter. The abundance of Metarhizium was significantly positively correlated with soil pH and CEC. Planting VV between rows of apple orchards, and enhancing the soil organic matter and nutrients content in a certain extent, helped to improve soil micro-ecological environment.

Simulation model for cucumber growth and development in sunlight greenhouse

CHENG Chen, FENG Li-ping, XUE Qing-yu, LI Chun, GONG Zhi-hong, DONG Chao-yang, WU Lu, WANG Chun-lei, LIU Shu-mei, LI Yi-zhuo, LI Zhen-fa

2019, 30(10): 3491-3500. doi:10.13287/j.1001-9332.201910.020

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The dynamic simulation of cucumber growth and development in sunlight greenhouse can provide technical support for the intelligent management of cucumber production. According to the cucumber response characteristics to light and temperature, the cucumber development module based on the algorithm of clock model was established by using data from four-stage experiment with ‘Jinyou 35’ as experiment variety in two years. Based on the relationship between the leaf growth and key meteorological factors (temperature and radiation), leaf area index (LAI) module was established with the accumulated product of thermal effectiveness and photosynthetically active radiation (TEP) as independent variables. The simulation module of cucumber dry matter production was established by taking into consideration the double integral of LAI and daily length in photosynthesis per unit leaf area as well as the respiratory expenditure of different organs. Combined with water content of organs, fresh weight simulation module of cucumber organs was constructed. The whole cucumber development and growth simulation model in greenhouse was built based on each sub-module. The model parameters were calibrated and determined. The results showed that root mean square error (RMSE) of simulated values and observed values of four deve-lopment stages (from transplanting date to stretch tendril, to initial flowering, to early harvested and to uprooting), was 3.9-10.5 d. The normalized root mean square error (nRMSE) was 6.5%-28.6%. The coincidence index (D) was 0.79-0.97. The relationship between LAI and TEP was the regression of ‘S’ type curve. The RMSE of simulated and observed LAI values was 0.19. The nRMSE was 17.2%. The D value was 0.90. The RMSE of dry weight of root, stem, leaf, flower and fruit of the simulated values and observed values were 0.39-8.94 g·m^-2. The nRMSE were 10.9%-17.7%. The D values were all above 0.98. The growth and development model of cucumber could accurately simulate the key development period of cucumber, leaf area and the dry and fresh weight of various organs and quantify the growth and development of cucumber in sunlight greenhouse.

Effects of PGPR inoculation on photosynthesis and physiological-ecological characteristics of apple seedlings under drought stress

XU Xue-dong, ZHANG Chao, QIN Cheng, SU Yun-yun, ZHOU Jie, ZHANG Hai, ZHANG Li-xin

2019, 30(10): 3501-3508. doi:10.13287/j.1001-9332.201910.024

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The effects of inoculation of rhizosphere-promoting bacteria (PGPR) on photosynthesis and physiological-ecological characteristics of apple tree seedlings under drought conditions were investigated in this study, aiming to provide a theoretical basis for the application of PGPR in plant drought resistance. In the pot experiment, the rhizosphere-promoting bacterium YX₂ which had both ACC deaminase activity and strong phosphorus solubilizing ability was selected as the tested strain. Apple seedlings were grown under four different irrigation levels i.e., control (CK), mild drought (LD), moderate drought (MD), and severe drought (SD) with soil moisture equivalent to 70%-80%, 55%-65%, 40%-50% and 25%-35% of field water holding capacity, respectively. Inoculation of PGPR alleviated the damaging effects of drought on growth by improving relative water content and chlorophyll content in apple tree seedlings. In addition, PGPR inoculated individuals exhibited higher antioxidant enzyme activity, chlorophyll fluorescence values, stomatal conductance and photosynthetic rate and lower relative conductivity and lipid peroxidation. Our results suggested that PGPR-YX₂ alleviated the negative effects of drought stress on the growth and net photosynthetic rate by improving the antioxidant system, water content and membrane functioning.

Effects of Rehmannia glutinosa consecutive monoculture on the community structure and diversity of phyllosphere bacteria

WU Lin-kun, CHEN Jun, YANG Bo, XIAO Zhi-gang, LU Cui-hong, WANG Juan-ying, LIN Wen-xiong

2019, 30(10): 3509-3517. doi:10.13287/j.1001-9332.201910.035

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Rehmannia glutinosa, a perennial herbaceous species, belongs to the family Scrophularia-ceae. As a staple medicinal material, its tuberous roots are highly valued in traditional Chinese medicine. However, R. glutinosa suffers from serious consecutive monoculture problems in production, which leads to a decline in both productivity and quality. Phyllosphere bacteria, the most abundant component of phyllosphere microorganisms, play crucial roles in plant growth and health. Characterization of phyllosphere bacteria could provide new insights into the mechanisms of consecutive monoculture problems and their control measures. Meanwhile, the varied taxa could be served as an important indicator of consecutive monoculture problems. The barcoded pyrosequencing of 16S rDNA genes combined with a culture-dependent approach was applied to characterize the shifts of bacterial community structure and diversity in the phyllosphere under consecutive monoculture of R. glutinosa. The results showed that consecutive monoculture clearly affected bacterial community structure in the phyllosphere. The phyllosphere bacterial communities of the two-year monocultured (TY) and the diseased plants (DP) were more similar, and different from the one-year monocultured (OY). The evenness, Shannon and Simpson diversity indices were significantly lower in TY and DP than in OY. Species annotation showed that bacterial community in R. glutinosa phyllosphere mainly consisted of Proteobacteria (91.2%), Firmicutes (5.1%) and Actinobacteria (3.7%). There was no significant difference in the number of detected bacterial taxa. However, Proteobacteria was significantly increased while Firmicutes and Actinobacteria were significantly decreased under consecutive monoculture. At the genus level, the relative abundances of genera Exiguobacterium, Bacillus and Arthrobacter, potentially beneficial microorganisms, were significantly higher in OY than that in TY and DP, but it was opposite for the genus Pseudomonas. The results from the culture-dependent approach and pathogenicity test showed that Pseudomonas plecoglossicida D9, widely isolated from the diseased leaves, was highly pathogenic to leaves. In conclusion, R. glutinosa monoculture resulted in distinct phyllosphere bacterial community variation with the accumulation of pathogen loads at the expense of beneficial microorganisms, which could contribute to the occurrence of leaf disease symptoms,and aggravate R. glutinosa replant disease in a monoculture regime.

Effects of Spartina alterniflora invasion in a seaward direction on variations of inorganic sulfur forms in marsh soils of the Minjiang River estuary, China

TONG Xiao-yu, SUN Zhi-gao, ZENG A-ying, CHEN Bing-bing, WANG Hua

2019, 30(10): 3518-3526. doi:10.13287/j.1001-9332.201910.004

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To explore the effects of Spartina alterniflora invasion in a seaward direction on variations of inorganic sulfur forms in marsh soils, the levels of inorganic sulfur forms (H₂O-S, Adsorbed-S, HCl-Soluble-S and HCl-Volatile-S) were determined in bare flat (BF, before invasion), S. alterniflora marsh after seaward invasion for one year (SA′) and S. alterniflora marsh after seaward invasion for three years (SA) in Shanyutan of the Minjiang River estuary with the method of space-for-time substitution. Results showed that the seaward invasion of S. alterniflora altered the stocks and distribution of inorganic sulfur form in marsh soils. Compared with BF, the contents of H₂O-S, Adsorbed-S and HCl-Volatile-S in soils of SA increased by 52.6%, 78.2% and 21.0%, respectively, while that of HCl-Soluble-S decreased by 3.4%. In contrast, the levels of H₂O-S, Adsorbed-S and HCl-Soluble-S in soils of SA′ increased by 43.9%, 70.6% and 29.6%, respectively, whereas that of HCl-Volatile-S decreased by 11.6%. The contents of total inorganic sulfur (TIS) in soils of SA and SA′ increased by 40.7% and 37.8%, while the stocks of TIS increased by 26.8% and 31.4%, respectively. The key factors affecting different forms of inorganic sulfur in marsh soils had changed due to the seaward invasion of S. alterniflora. In particular, the key factors affecting the variations of H₂O-S contents changed from soil grain composition and bulk density in BF to soil organic matter in SA′ and SA. The seaward invasion of S. alterniflora significantly increased the content of TIS in marsh soils, which was mainly contributed by H₂O-S and Adsorbed-S. Thus, it was concluded that the seaward invasion of S. alterniflora significantly increased the supply capacity of available sulfur in marsh soils, which, to some extent, accelerated its seaward invasion.

Spatial and temporal differences and influencing factors of ecological capital efficiency in Northeast China

SHI Jian, HUANG Ying-li

2019, 30(10): 3527-3534. doi:10.13287/j.1001-9332.201910.012

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Ecological capital is an important fulcrum for the construction of ecological civilization. Measuring the spatial and temporal changes and influencing factors of ecological capital efficiency can help understand the current status of ecological capital efficiency and improve the level of ecological civilization to achieve green development. We used the super-efficient DEA model and Malmquist index to measure the spatial and temporal changes of ecological capital efficiency in Northeast China and analyzed the influencing factors. The results showed that the ecological capital efficiency in Northeast China was generally good, showing a trend of rising first and then decreasing. The ecological capital efficiency of Heilongjiang was high, showing U-shaped development, while that in Jilin and Liaoning provinces was relatively low. Results from the Malmquist index analysis showed that technological progress was the main driving force for the improvement of ecological capital efficiency. The results of Tobit regression analysis showed that the environment scale effect and the demographic effect variables had a significant positive impact on the efficiency of ecological capital. The low efficiency of science and technology investment led to negative correlation between environmental technology effect variables and ecological capital efficiency. To improve the ecological capital efficiency in Northeast China, on the one hand, we should accelerate the adjustment of industrial structure and develop ecological economy, on the other hand, we should increase the input efficiency of science and technology funds and rely on technological progress to realize green development of economy in Northeast China.

Peak volume and time of energy-related CO₂ emissions in Jiangsu Province, China based on long-range energy alternatives planning system model

WANG Chun-chun, WANG Yuan, ZHU Xiao-dong

2019, 30(10): 3535-3543. doi:10.13287/j.1001-9332.201910.017

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China has put forward CO₂ emissions reduction target (committing to achieve CO₂ emissions peak or plateau by 2030) to prevent global climate change. With Jiangsu Province as a case, we explored whether China could achieve the 2030 CO₂ emissions reduction target. We predicted the peak volume and time of CO₂ emission in three scenarios, i.e., quick scenario, medium scenario, slow scenario, respectively, based on the long-range energy alternatives planning system (LEAP) model and the logarithmic mean Divisia index decomposition approach. The results showed that, during the period 2000 to 2015, the economic scale effect was the most important driver, whose contribution to the increase of total CO₂ emissions was as high as 147.4%. The technology progress effect was the main mitigation factor for CO₂ emissions, which caused CO₂ emissions to decrease by 60.4%. In addition, the contributions of energy structure effect, industrial structure effect, per capita income effect and population scale effect to CO₂ emissions were -5.3%, 9.7%, 11.0%, and 0.6% respectively. In quick and medium scenarios, the peak CO₂ emissions of Jiangsu Province would be 701 million tons in 2025, and 795 million tons in 2029, respectively. In slow scenario, however, Jiangsu Province could not achieve the 2030 CO₂ emissions reduction target. To achieve the 2030 target, Jiangsu Province needs to adopt some strategies, including actively developing the tertiary industry to balance the economic structure, continuously promoting energy saving and emissions reduction technologies to reduce energy consuming intensity, and vigorously deploying clean energy to optimize the energy consuming structure.

Spatial differentiation characteristics and influencing factors of urban and rural settlements in Tibet, China

QIAO Fu-wei, BAI Yong-ping, ZHOU Liang, CHE Lei, WANG Fan

2019, 30(10): 3544-3552. doi:10.13287/j.1001-9332.201910.015

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Located in the hinterland of the Qinghai-Tibet Plateau, Tibet has very limited space sui-table for human living. The spatial distribution of settlements in Tibet is restricted by multiple factors. To reveal the spatial distribution characteristics and explore the main influencing factors of settlements in Tibet, we extracted patch data from the high-resolution images of urban and rural settlements in Tibet based on visual interpretation. Methods such as the kernel density analysis, space hotspot detection, Geodetector and others were applied to analyze the spatial differentiation characteristics and influencing factors, with the aim to provide reference for future settlements selection and formulation of relevant policies on regional economic development in the plateau region. The results showed that urban and rural settlements in Tibet had a clustering pattern, with different overall density distribution. Lhasa was a high-density core, and Ngari Prefecture, Qamdo, and Nyingchi were the “core-edge” structures with low-density edges. The settlement density of Lhasa was as high as 220 ind·km^-2, while that of Ngari Prefecture, Qamdo and Nyingchi was only 5.7 ind·km^-2. The gap between the two regions was more than 43 times. The clustering of high and low value clusters in urban and rural settlements was remarkable. The number of high-value of large plaques was rare, and the number of low-values of small plaques was dominant. The area of high-value cluster accounted for only 3.7%, concentrated in Lhasa and Lhoka. The proportion of low value cluster area reached 67.2%, mainly distributed in Ngari Prefecture and Nagqu on the Qiangtang Plateau. There were six types of urban and rural settlements in Tibet, which formed two circle structures in the “One River and Two Streams” basin and the “Three Rivers” basin. From the inside to the outside, the large plaque-dominated type, medium-density and cluster-like type, high-density and point-scattered type, low-density and point-scattered type and high-altitude and uninhabited type was successively distributed. Lhasa was dominated by medium-density and cluster-like type, accounting for 31%. Lhoka was dominated by low-density and point-scattered type, accounting for 38%. Qamdo was mainly low-density and point-scattered type, accounting for 51%. The Ngari Prefecture, Nagqu and Shigatse were dominated by high-altitude and uninhabited type, and the proportion of the Ngari Prefecture was as high as 64%. The effects of different factors on the spatial distribution of urban and rural settlements in Tibet were distinctly different. The population and GDP were highly decisive for the distribution of urban and rural settlements. In addition, urban settlements showed strong road orientation, while rural settlements were more characterized by river orientation.

Ecological risk assessment of landslide disasters based on potential loss of ecosystem services

WANG Hui-fang, LIN Zi-yan, XIAO Yi, LU Hui-ting, ZHANG Wen, ZHAN Yun-jun, YAN Yan

2019, 30(10): 3553-3562. doi:10.13287/j.1001-9332.201910.019

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Landslides are common geological calamities in mountainous regions, which not only threaten social and economic development and residents’ safety but also cause ecosystem damage, with consequences on human welfare. A more comprehensive and systematic reference for disaster prevention and mitigation with ecosystem services loss as an index for the potential damage of ecosystem could aid the progress of landslide ecological risk assessment. Five provinces in Southwest China (Sichuan, Yunnan, Guizhou, Guangxi and Chongqing) have diverse landforms, complex stratum and lithology, and active geological tectonic movements, which are the most landslide prone areas in China. In this study, the ecological risk assessment framework, model and indicator were constructed from three dimensions, including disaster risk, vulnerability and potential loss of the ecosystem. Disaster risk was based on the comprehensive analysis of factors such as geology, topo-graphy, landform, precipitation, and their mutual relationship. The vulnerability of the ecosystem was characterized by landscape patterns indices. The potential loss was measured by ecosystem service to evaluate the ecological risk associated with landslide hazards in the five provinces of Southwest China. The results showed that the areas with high potential loss of ecosystem services were mainly distributed in the south of Ailao Mountain in Yunnan Province, Qionglai Mountain of Sichuan Pro-vince, Hengduan Mountains, Dadu River Basin, Northwest Guangxi Autonomous Region, and eastern area of Dayao Mountain. The high ecological risk of landslide hazard in the study area mainly distributed in the areas of Min Mountain, Qionglai Mountain, Wuliang Mountain, Ailao Mountain, Miao Ridge, Leigong Mountain, and Dadu River basin. With respect to altitude, 500-1500 m was the main high-risk areas, accounting for 37.9% of the high-risk area. In terms of ecosystem types, forests are the high-risk areas, accounting for 66.4% of the high-risk areas. Landslide monitoring and early warning in the high ecological risk areas should be strengthened, through strengthening ecosystem protection in the region and improving the stability and resistance of ecosystems.

Phenological characteristics of airborne pollen and its relationship with meteorological factors in Haidian District, Beijing, China during the period of 2012-2016

LIU Yi-gang, LYU Shi-hua, LIU Jian-zhong, LIU Wen-jun, HUANG Kai-long, ZHANG Jia-yi, OUYANG Yu-hui, LI Ying

2019, 30(10): 3563-3571. doi:10.13287/j.1001-9332.201910.014

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We monitored the type and content of airborne pollen in Haidian District, Beijing City from 2012 to 2016 by the gravity precipitation method, and analyzed the variety of pollen, peak distribution features and changes of its content, and discontinuous variation of concentration. Multiple time scale analysis was carried out for pollen concentration by the ensemble empirical mode decomposition method (EEMD). The relationship between pollen concentration and meteorological factors was analyzed. The results indicated that during the research period, the main types of airborne pollen changed. Woody plants such as Cupressaceae and Salicaceae instead of herbaceous plants contributed the most content of pollen. There was no significant change of the yearly peak distribution of pollen concentration. The concentration in recent five years reduced, while the concentration of herbaceous plants (such as Scolopacjdae) increased. During the statistics period, pollen concentration showed discontinuous changes in early April, late May and early August. Pollen concentration had the change cycle of quasi 2 d, quasi 51 d and quasi 128 d. Among all meteorological factors, temperature played a dominant role in driving the concentration, which may significantly rise during 16 to 18 ℃. The impact of temperature changes on the daily concentration may be delayed and continuous; it is often highly related to the concentration 2-7 d later. Sunshine duration and wind speed had the most significant impact on daily pollen concentration.

Assessment of enhancement release of Oncorhynchus keta in Suifen River, Northeast China

WANG Ji-long, LIU Wei, YANG Wen-bo, LI Pei-lun, WANG Wei-kun

2019, 30(10): 3572-3578. doi:10.13287/j.1001-9332.201910.037

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To evaluate the effects of enhancement release of Chum salmon (Oncorhynchus keta) in Suifen River, the homing Chum salmon was monitored in Dongning section of Suifen River from 2012 to 2017. A total of 462 samples were collected, 41 samples out of which were tagged indivi-duals which were cut off adipose fin before they were released. The recapture rate and the effects of Chum salmon enhancement release were analyzed and evaluated based on the releasing information. The results showed that the entire recapture rate of Chum salmon from 2010 to 2012 was 0.295%, and the input-output ratio of enhancement release was 1:2.87. Both the tagged and non-tagged groups were composed of 1⁺ to 5⁺ age individuals, with the average age being 3.93 and 3.63 years, respectively. The fork length at 50% individuals reached sexual maturity (L₅₀) was estimated using a logistic moderating function, which was 53.13 cm and 49.89 cm for tagged and non-tagged groups, respectively. Results from ARSS analysis showed that there was no significant difference in fork length growth between tagged and non-tagged groups, but a significant difference in sexual maturity ratio. Our results confirmed the positive effects of enhancement release on recovery of Chum salmon resource and provided suggestions for the enhancement release efforts.

Effects of silver nanoparticles on pupation, eclosion, life span, apoptosis and protein expression in Drosophila melanogaster

MENG Shuai-shuai, WANG Bo, LIN Xin-da

2019, 30(10): 3579-3588. doi:10.13287/j.1001-9332.201910.036

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Silver nanoparticle is widely used in the field of medicine because of its strong and effective antibacterial action. However, it has potential biological toxicity. In this study, the classical model organism, Drosophila melanogaster, was used to explore underlying mechanism for the toxic effects of silver nanoparticle. The pupation rate, eclosion time, eclosion rate and lifespan of Oregon R, w1118, and MTF mutants under different concentrations of silver nanoparticle were measured. The lacZ activity of rpr-lacZ strain was used to determine apoptosis of imaginal disc after treated with different concentrations of silver nanoparticle. The difference of intestinal protein expression in MTF mutants treated with different concentrations of silver nanoparticle was studied by SDS-PAGE. The amino acid sequence of differential proteins was further analyzed by mass spectrometry. The results showed that pupation rate and eclosion rate of MTF mutants significantly decreased when the concentration of silver nanoparticle increased to 200 μg·mL^-1 and above. When the concentration of silver nanoparticle increased to 800 μg·mL^-1, the rate of pupation and eclosion was significantly reduced, with the time of pupation and eclosion being not correlated to the concentration of silver nanoparticle. The concentrations of silver nanoparticle had no effect on the lifespan of Oregon R and w1118, while 200 μg·mL^-1 silver nanoparticle significantly reduced the average lifespan of MTF mutant. Apoptosis increased with increasing concentration of silver nanoparticle. Results from SDS-PAGE and mass spectrometry analysis showed that the expression levels of proteins such as ATP kinase, heat shock protein and glucose metabolism related enzymes increased with increasing concentration of silver nanoparticle. Our results showed that high concentration of silver nanoparticle would reduce the survival rate of Drosophila, promote apoptosis and the expression of some proteins, which provided a theoretical basis for further understanding of the toxic mechanism of silver nanoparticle.

Functional diversity of fishes in the Minjiang Estuary, Southeast China

FENG Chen, HE Xiong-bo, ZHAO Chun-xu, LI Jun, KANG Bin

2019, 30(10): 3589-3595. doi:10.13287/j.1001-9332.201910.040

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Based on samples collected by bottom trawl in May, August, November and December 2016 in the Minjiang Estuary, species richness and functional diversity of fishes, as well as their spatial-temporal variations, were quantified by a trait-based approach. The functional diversity varied with the changes of species richness. The species richness averaged across all stations were (17.8±5.1) species in spring, (22.4±5.6) in summer, (17.7±6.3) in autumn, and (12.1±2.3) in winter. Functional diversity also showed seasonal variation, with the highest in summer as (33.94±28.70), followed by (9.93±8.83) in winter, (11.30±7.55)in spring and (19.05±19.32)in autumn. The key functional species varied seasonally, as Setipinna taty contributing to 26% of the total functional value in spring, Polydactylus sextarius at 26% in summer, Harpadon nehereus climbing to 69% in autumn, and Collichthys lucidus at 38% in winter. The seasonal variations of fish species function were determined by life history and its interaction with other species.

Advances in mechanisms of nutrient exchange between mycorrhizal fungi and host plants

FENG Huan, MENG Pan-pan, DOU Qing, ZHANG Shou-xia, WANG Hai-hua, WANG Chun-yan

2019, 30(10): 3596-3604. doi:10.13287/j.1001-9332.201910.034

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Mycorrhizae, formed through the colonization of soil mycorrhizal fungi into the roots of host plants, are common symbiosis in the terrestrial ecosystems. The establishment of mycorrhizae is mainly based on the bidirectional nutrient exchanges between the symbiotic partners. Mycorrhizal fungi can absorb mineral nutrients, such as nitrogen and phosphorus, from soil and transport them to the host plants for their growth. As an exchange, host plants supply mycorrhizal fungi with the carbohydrates in the form of lipids or sugars, which are essential for fungal growth. In recent years, the mechanism of nutrient exchange between the mycorrhizal fungi and host plants has been a hot research topic. Important progresses have been achieved in mechanisms of host plants nutrient uptake and transport mediated by the mycorrhizal fungi. In this review, recent advances in nutrient exchange between arbuscular mycorrhizal fungi, ectomycorrhizal fungi and host plants were summarized, especially in the absorption and bidirectional transfer mechanisms of important nutrients, such as carbon, nitrogen and phosphorus. The potential regulatory effects of nutrient exchange in the mycorrhizal development were also reviewed. In addition, key problems and prospects of related researches were analyzed. This paper would be meaningful for the establishment of mycorrhizal model and the optimization of mycorrhizal effects.

Research progress on the monitoring methods of atmospheric nitrogen deposition

WU Yu-feng, GAO Xiao-peng, GUI Dong-wei, LIU Xue-jun

2019, 30(10): 3605-3614. doi:10.13287/j.1001-9332.201910.008

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As an important component of global nitrogen (N) biogeochemical cycle, atmospheric N deposition refers to the removal process of reactive N, including oxidized N (NO_y) and reduced N (NH_x), from the atmosphere to earth surface through dry and wet deposition. Nitrogen deposition can exert important impacts on the structure and functioning of both terrestrial and aquatic ecosystems. Increasing N deposition poses a potential threat to natural ecosystems and human health. It is a challenge to accurately monitor the composition and flux of dry and wet N deposition in different ecosystems, using a unified technology. Here, we reviewed the research progress on monitoring methods of dry and wet N deposition in China and aboard, including micrometeorology, inferential method, model estimation, surrogate surface, precipitation collection, and ion exchange resin methods. We further discussed the advantages and disadvantages of each method in terms of its applications at regional, national, and global scales. This review would provide a methodological support to establish national monitoring network for atmospheric N deposition.

Advance in insect phototaxis and the development and application of colored sticky boards

GUO Zu-guo, WANG Meng-xin, CUI Lin, HAN Bao-yu

2019, 30(10): 3615-3626. doi:10.13287/j.1001-9332.201910.032

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The visual communication between insect and plant is one of the key sensory signal channels for the survival, reproduction and defense of insects. The colored sticky boards, which are developed based on insects positive phototaxis and as one of the effective green pest control measures, have been widely applied for monitoring, forecasting and mass-trapping of many diurnal agricultural and forestry insect pests. In addition, they could be used to attract beneficial insects to the target areas to prey on or parasitize harmful insects, and to aid in pollination. Here, we discussed the insect phototaxis theory and the “attract and kill” mechanism of colored sticky boards and reviewed the effects of color, shape, size, height, density, facing direction, working duration of the sticky boards, as well as plant morphological characters and insect physiological status on trapping efficacy. We summarized various application techniques of the color sticky boards on different target pest insects in tea plantations, vegetable fields and greenhouses, etc. We analyzed various application technologies of combining colored sticky boards with synthetic sex pheromone attractants and/or botanical attractants and their efficacy; then evaluated the pros and cons of using the colored sticky boards for pest control or monitoring. Accordingly, we provided suggestions for improvements and discussed the trapping efficacy assessment and cost-benefit analysis. Finally, we proposed the R&D directions of next generation colored sticky boards, especially its combination with synthetic pheromones/kairomones as an important integrated pest management (IPM) measure, and the future of the colored sticky board industry.

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