Table of Content

15 August 2020, Volume 31 Issue 8

Previous Issue    Next Issue

Temporal effects of thinning on the composition and growth of regenerated woody plants in Larix kaempferi plantations

XIE Jin, YAN Qiao-ling, ZHANG Ting

2020, 31(8):  2481-2490.  doi:10.13287/j.1001-9332.202008.010

Asbtract ( 294 )   PDF (1083KB) ( 67 )  

Understanding the temporal effects of thinning on the composition and growth of regene-rated broadleaved woody species in coniferous plantations can provide profound references for promoting the conversion of monoculture plantations into mixed conifer-broadleaved forests, which could solve the problem that the production and ecological functions of monoculture plantations cannot be balanced. We compared the composition of regenerated woody plant species in Larix kaempferi plantation with short-term (1-3 years), medium-term (4-9 years) and long-term (>9 years) after thinning. Furthermore, we selected three regenerated tree species with higher importance value and reciprocal symbiosis with L. kaempferi, which differed in shade tolerance, including shade-intolerant species Quercus mongolica, intermediate shade-tolerant species Acer mono, and shade-tolerant species Tilia mandschurica. We analyzed the relationships between light conditions (i.e., canopy density) and the growth (i.e., base diameter and height) of those species in L. kaempferi plantation with different terms after thinning. The results showed that 46 species of regene-rated broadleaved woody plants were recorded in thinned plantations. The common and dominant tree in different terms after thinning was A. mono, and the shrub species were Lonicera japonica and Euonymus alatus. With the increasing time after thinning, species richness of regenerated trees decreased, but the ratio of tree to shrub species increased and the intermediate shade-tolerant tree species took the dominant position. The temporal effect of thinning on the growth of three tree species was affected by shade tolerance ability. Basal diameter and height of T. mandschurica were higher than those of Q. mongolica and A. mono. With the increases of time after thinning, basal diameter of T. mandschurica and height of A. mono were more sensitive to light, indicating that there were respectively “a shade tolerance strategy” and “a shade avoidance strategy” to adapt to the post-thinning environment. The effects of thinning on the composition and growth of regenerated broadleaved woody species in L. kaempferi plantations were significantly time-sensitive. When deve-loping thinning measures to promote the regeneration of broadleaved trees in plantations, we should consider to extend the thinning interval appropriately to ensure the growth of broadleaved tree seedlings (e.g., T. mandschurica and A. mono) and accelerate their migration into the canopy layer. This would promote the formation of mixed conifer-broadleaved forests and eventually realize the sustainable development of plantations.

Stoichiometry of soil extracellular enzymes and its seasonal variation in natural forests with different altitudes in northern Greater Khingan Mountains, China

JI Li, MA Li-xin, CHENG Zheng-lei, ZHU Qing-chao, ZHANG Yan, YANG Yu-chun, YANG Li-xue

2020, 31(8):  2491-2499.  doi:10.13287/j.1001-9332.202008.005

Asbtract ( 341 )   PDF (1244KB) ( 156 )  

In this study, we examined the characteristics and influence mechanism of soil extracellular enzyme activity (EEA) and enzymatic stoichiometry in different soils in forests at different altitudes (750-1420 m) in Aokelidui Mountains in the north of the Greater Khingan Mountains. The results showed that altitude, season and their interactions significantly affected the activities of β-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), L-leucine aminopeptidase (LAP), and acid phosphatase (AP). In May, BG and NAG activities gradually increased with increasing altitude, while AP activities increased first and then decreased with increasing altitude. In July, NAG activity increased with altitude, while AP activity increased first and then decreased. In September, NAG activity changed significantly in different altitudes, with the highest activity at 1420 m (124.22 nmol·h^-1·g^-1). With the increases of altitude, ln(BG): ln(NAG+LAP) showed a decreasing trend. Except for the altitude of 830 m, stoichiometric ratio in all altitudes was the highest in July. The ratio of logarithmic conversion of soil C, N, and P invertase activity was 1:1.25:0.82. Altitude and soil temperature were the main factors affecting soil extracellular enzyme activities. There was a significant positive correlation between soil temperature and BG, NAG, and AP. Enzymatic stoichiometry ln(BG):ln(NAG+LAP) and ln(NAG+LAP):ln(AP) showed significant positive and negative correlations with soil pH, and had a negative and positive relationship with DOC. The ratio of ln(BG):ln(AP) was greatly affected by soil bulk density.

Nectar productivity of Tilia amurensis in a broadleaved-conifer mixed forest in Changbai Mountains, China

SUN Zhen, LIU Qi-jing, XU Zhen-zhao, XU Wei-ze

2020, 31(8):  2500-2506.  doi:10.13287/j.1001-9332.202008.008

Asbtract ( 342 )   PDF (966KB) ( 25 )  

Tilia amurensis is one of (co-)dominant species in the broadleaved-conifer mixed forest in Northeast China, with high commercial and nectariferous values. We estimated the quantity of nectar secretion from individual trees to population or stand levels based on observation and statistical analysis. An equation for individual-tree nectar secretion was established, which was used to estimate nectar quantity at the stand level. We analyzed the relationships between nectar secretion and basal area or stem volume. The booming time for single flower was in average 6-8 days, with a nectar secretion period of about five days. The quantity for the entire period was estimated at 8.58 mg per flower. Sugar contents in the nectar, average 37.7%, showed diurnal variations, being high in the mid-noon and low in the early morning and late afternoon. The average diameter (DBH) of the species was approximately 40 cm, which was estimated to possess as much as 18×10⁴ single flowers and 1.56 kg (or pure sugar 0.588 kg) of nectar. At the stand level, the nectar production potential was 79-147 kg (or 0.0686-0.1285 m³, pure sugar 29.78-55.42 kg) per hectare. There was a close correlation between nectar quantity and basal area or timber volume at both individual and stand levels, which could be used to estimate the nectar quantity for macro-scale forest area based on inventory data.

Effects of slope position and aspect on structure and species diversity of shrub community in the Jiajin Mountains, Sichuan Province, China

ZHANG Rong, YU Fei-yan, ZHOU Run-hui, DONG Hong-jun, WANG Min, YE Xin, HAO Jian-feng

2020, 31(8):  2507-2514.  doi:10.13287/j.1001-9332.202008.004

Asbtract ( 472 )   PDF (881KB) ( 81 )  

We examined the impacts of slope direction and position on the community structure and species diversity of shrub community in Jiajin Mountains. The results showed that a total of 186 vascular plant species belonging to 50 families and 127 genera were recorded in the 24 sample plots. 32 species belonging to 14 families, 22 genera were recorded in the shrubs layer, with most species distributed at lower position of the shady slope. 154 species belonging to 43 families and 109 genera were recorded in the herbaceous layer, with the species number being the lowest on the shady slope. The average height of the shrub layer showed a decreasing order of sunny slope, semi-sunny slope, and shady slope, while an opposite order was observed for the average density. The average height of the herb layer was in the decreasing order of the shady slope, semi-sunny slope, sunny slope, whereas no significant changes were observed for the average density. The slope position had significant effect only on the average height of the herbaceous layer on the sunny slope. The overall level of species diversity in the shrub layer on the shady slope was relatively high, while that in the herbaceous layer was relatively high at the lower position of the sunny slope and at the middle position of the shady slope. Slope aspect had significant effect on species richness index, Shannon diversity index, Simpson dominance index, Pielou evenness index of shrub and herb layers except for Simpson index of herb layer. Slope position did not affect these indices. The interaction effect of slope aspect and position on the diversity index for herb layer was greater than that for the shrub layer. Results from redundancy analysis showed that species diversity was related to sin(aspect), cos(aspect), and community structure.

Kinetic parameters and temperature sensitivity of soil nitrogen and phosphorus transforming enzymes in Robinia pseudoacacia plantations under different vegetation zones on the Loess Plateau, China

ZHAO Zi-wen, WANG Guo-liang, WU Yang, CHEN Wen-jing, LI Yang-yang, LIU Guo-bin, XUE Sha

2020, 31(8):  2515-2522.  doi:10.13287/j.1001-9332.202008.003

Asbtract ( 272 )   PDF (1662KB) ( 47 )  

Soil enzymes are catalysts for organic matter decomposition, the kinetic characteristics of which are important indicators of the catalytic performance of enzymes, with important role in evalua-ting soil health quality. We examined the responses of soil enzyme kinetic parameters to temperature change and the variation characteristics of their temperature sensitivity (Q₁₀) in Robinia pseu-doacacia plantation soil under three different vegetation zones on the Loess Plateau. The results showed that the potential maximum reaction rate (V_max) and the half-saturation constant (K_m) of alanine transaminase (ALT), leucine aminopeptidase (LAP) and alkaline phosphatase (ALP) all increased linearly with the increasing incubation temperature. The zonal regularity of forest zone > forest-steppe zone > steppe zone was presented in V_max. The temperature sensitivity of V_max(Q10(V_max)) ranged from 1.14 to 1.62, and the temperature sensitivity of K_m(Q_10(Km)) ranged from 1.05 to 1.47, with both values being lower in forest-steppe zone than other vegetation zones. In low and high temperature regions, the variations of Q₁₀ in different soil enzymes differed among vegetation zones. Results from redundancy analysis showed that Q₁₀ had a significant correlation with environmental variables, especially soil nutrients, indicating that Q₁₀ would be affected by other environmental factors besides temperature.

Responses of litter decomposition in two subalpine plantations to simulated nitrogen deposition in central Yunnan, China

ZHANG Yu-jian, SONG Ya-li, WANG Ke-qin, YANG Xiao-yu, XING Jin-mei, ZHANG Zhuan-min

2020, 31(8):  2523-2532.  doi:10.13287/j.1001-9332.202008.034

Asbtract ( 330 )   PDF (1805KB) ( 49 )  

From February 2018 to January 2019, a field experiment of simulated nitrogen (N) depo-sition was conducted in Pinus armandii and Pinus yunnanensis plantations in the subalpine region of central Yunnan, China. The litterbag method was used for in situ litter (leaf and twig) decomposition experiment in both plantations. Four levels of N addition were applied, i.e., control (CK, 0 g N·m^-2·a^-1), low nitrogen (LN, 5 g N·m^-2·a^-1), medium nitrogen (MN, 15 g N·m^-2·a^-1), and high nitrogen (HN, 30 g N·m^-2·a^-1). The results showed that the annual decomposition rates of leaf and twig in P. armandii were 34.8% and 18.0%, which were higher than the 32.2% (leaf) and 16.1% (twig) in P. yunnanensis. Under N deposition, the LN treatment reduced the time of 95% mass loss of leaf and twig litter in P. armandii by 0.202 and 1.624 years, the MN treatment reduced by 0.045 and 1.437 years, and the HN treatment increased by 0.840 and 2.112 years, respectively. In the P. yunnanensis plantation, the LN treatment reduced the time of 95% mass loss of leaf and twig litter by 0.766 and 4.053 years, while the MN treatment increased by 0.366 and 0.455 years, and the HN treatment increased by 0.826 and 0.906 years, respectively. Litter (leaf and twig) decomposition of both P. armandii and P. yunnanensis were promoted by low N treatment and inhibited by high N treatment. The effects of N deposition on litter decomposition of two plantations were significantly correlated with the contents of cellulose and lignin in litter. In conclusion, the responses of litter decomposition to N deposition mainly depended on the litter substrate, especially cellulose and lignin contents.

Responses of seedling growth in subtropical secondary broad-leaved forest to nitrogen and phosphorus addition in Jiulian Mountain, China

LIU Bin, CHEN Wei, CHEN Fu-sheng, TANG Run-yu, WANG Xiao-dong, CHENG Yi-qing, BU Wen-sheng

2020, 31(8):  2533-2540.  doi:10.13287/j.1001-9332.202008.020

Asbtract ( 355 )   PDF (849KB) ( 60 )  

An experiment with four treatments of control (CK), N addition (100 kg N·hm^-2·a^-1), P addition (50 kg P·hm^-2·a^-1) and N + P (100 kg N·hm^-2·a^-1 + 50 kg P·hm^-2·a^-1) were conducted to examine the responses of plant height, ground diameter, crown width, specific leaf area, and mortality of seedlings to N and P addition. Under P addition, growth rates of plant height and ground diameter of seedlings decreased significantly by 45.1% and 30.3%, respectively. Fertilization affected the mortality of main constructive tree species. N addition significantly increased seedling mortality of Castanopsis carlesii to 25.1%. Fertilization treatment significantly increased mortality of Castanopsis fargesii to 25.1%-31.3%, while N addition and P addition signi-ficantly reduced mortality of Schima superba and Machilus nanmu. Fertilization significantly decreased the importance value of S. superba and C. fargesii in the seedling community. N addition and P addition significantly increased the importance value of M. nanmu seedling. The combined N and P addition significantly decreased Shannon index and Simpson index of the seedling community. Seedling growth was mainly affected by soil ammonium, available phosphorus, total nitrogen, canopy openness, and specific leaf area. Seedling mortality was mainly affected by soil ammonium, available phosphorus and canopy openness. Synthetically, N and P addition affected seedling growth mainly by regulating soil nitrogen and phosphorus availability and changing leaf functional trait. It accelerated the death of ectomycorrhizal tree species (C. carlesii and C. fargesii), changed the importance value of constructive species in seedling community, reduced species diversity, and ultimately changed community structure of adult trees in subtropical secondary broad-leaved forest.

Responses of soil extracellular enzyme activities to the anthropogenic transition from desert grassland to shrubland in eastern Ningxia, China

GUO Tian-dou, YU Lu, SUN Zhong-chao, MA Yan-ping, ZHAO Ya-nan, LIANG Dan-ni, LI Zhi-li, WANG Hong-mei

2020, 31(8):  2541-2548.  doi:10.13287/j.1001-9332.202008.001

Asbtract ( 231 )   PDF (1156KB) ( 37 )  

To understand the responses of soil extracellular enzyme activities to the desert grassland-shrubland anthropogenic transition, we examined soil properties and six extracellular enzyme activities, in soil under vegetation patches and bare interspaces in desert grassland, grassland edge, shrubland edge, shrubland in a typical anthropogenic desert grassland-shrubland mosaic in desert steppe of eastern Ningxia, China. The six measured enzymes included cellobiohydrolase, β-1,4-xylosidase, β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase and alkaline phosphatase. We found that soil moisture, soil organic carbon, total nitrogen, total phosphorus, microbial biomass carbon and microbial biomass nitrogen decreased significantly by 26.0%-88.5% with the process of the desert grassland-shrubland anthropogenic transition. All soil properties, except soil organic carbon and soil moisture in grassland edge site, were 3.9%-82.3% higher under vegetation patches than those in bare interspaces in each site. The six extracellular enzyme activities also decreased by 22.1%-82.4% in the transition process, especially for leucine aminopeptidase and alkaline phosphatase, showing significant decrease by 82.4% and 75.5%, respectively. All extracellular enzyme activities but β-1,4-N-acetylglucosaminidase in shrubland were significantly higher by 10.7%-42.7% under vegetation patches than those in bare interspaces in each site. The activities of six extracellular enzymes were all positively correlated with each other. All of them were positively correlated with soil properties. Moreover, activities of these soil extracellular enzymes responded more positively to the changes of microbial biomass carbon, microbial biomass nitrogen, and total nitrogen in the process of anthropogenic transition.

Simulating site index of Juglans mandshurica using a random effect model in three provinces of Northeast China

LUO Ye, WANG Jun, YANG Yu-chun, JI Li, ZHU Rui, YANG Bin, ZHANG Li-jie, QI Yong-hui

2020, 31(8):  2549-2557.  doi:10.13287/j.1001-9332.202008.006

Asbtract ( 436 )   PDF (954KB) ( 26 )  

To evaluate site quality and provide scientific evidence, the mixed effect model of polymorphic site index of Juglans mandshurica was accurately simulated in the three provinces of Northeast China. A total of 197 plots in the 23 typical regions of Liaoning, Jilin and Heilongjiang provinces were set by the sample circle method, from which we got 1537 height-age data of J. mandshurica. The site factors were divided, assigned and calculated using variance analysis and model fitting. The results showed that slope position was the dominant factor affecting the growth of dominant wood of J. mandshurica, followed by soil depth, slope and aspect. After fitting and analyzing eight common basic models, we found that the logistic model H=a/[1+exp(b+cA)] was the optimal one (R²=0.70), with a mean absolute error (MAE) of 2.52. When the four main influen-cing factors were randomly combined, the optimal site index model of the stochastic combination (M_8.15) was obtained with R² of 0.90, which improved the fitting accuracy of the base model. The K-means clustering method was used to further divide the initial groups of site types into six groups. We established the nonlinear mixed effect model M_final, H=(20.1837+u_i)/[1+exp (1.7352-0.0961A)]+ε_ij, with R² and Akaike's information criterion (AIC) being 0.92 and 912.65, respectively, which could significantly improve the fitting and accuracy of the model. The equation could be used for the accurate evaluation of site quality of J. mandshurica under the complex site types in the three provinces of Northeast China.

Physiological response of Xinjiang wild walnut germplasm to low temperature stress

ZHANG Min-huan, WANG Jian-cheng, YANG Hong-lan, ZHANG Dao-yuan, DENG Peng-cheng, CUI Zhi-jun

2020, 31(8):  2558-2566.  doi:10.13287/j.1001-9332.202008.002

Asbtract ( 393 )   PDF (2148KB) ( 39 )  

We examined the physiological response of 1-year-old branches of 37 Xinjiang wild walnut germplasm resources in Gongliu wild walnut forest under cold temperatures (-20 ℃ and 4 ℃) for 12 hours, compared the responses with that of Juglans mandshurica. The relative conductivity (REC), free proline (PRO), soluble sugar (SS), malondialdehyde (MDA) content and peroxidase (POD) activity were measured in an artificial climate chamber by simulating spring low temperature. Subordinate function and principal component analysis were used to evaluate the physiological response of walnut germplasm to low temperature. The results showed that the REC, PRO, SS, MDA content and POD activity of Xinjiang wild walnut were increased. By evaluating the relationship between low temperature resistance and habitat, we found that cold tolerance level was middle valley > east valley > west valley > general valley. Xinjiang wild walnut showed stronger cold tolerance than J. mandshurica. Seven germplasm with cold resistance were selected from the total 37 wild walnut germplasm in Xinjiang, which provided a reference for improving walnut varieties and their responses to sudden weather change in late spring and other growing stages.

Storage and ecological stoichiometry of soil carbon, nitrogen, and phosphorus under diffe-rent ecological restoration patterns in the alpine desertified grassland of northwestern Sichuan, China

LI Sen, LI Ling, FAN Hua, LUO Xue-mei, GOU Xiao-lin, TU Wei-guo

2020, 31(8):  2567-2573.  doi:10.13287/j.1001-9332.202008.007

Asbtract ( 304 )   PDF (489KB) ( 63 )  

We analyzed carbon (C), nitrogen (N), and phosphorus (P) contents and their stoichiometric characteristics of sandy soil in four restoration patterns after 5 years restoration in the northwest Sichuan, China, including planting grass alone (PG), planting shrub alone (PS), shrub-grass intercrop (SG), and shrub-herb intercrop (SH). The untreated sand land was set as control (CK). The results showed that soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), C/N, C/P, and N/P were increased under different restoration patterns, especially under shrub-grass intercrop (SG). In 0-10 cm and 10-20 cm soil layers, the contents of SOC and TN under SG were significantly higher than that under other patterns. In 0-40 cm soil layer, the SOC storage under SG was higher than that under PG, PS, SH, and CK by 13.4%, 15.6%, 17.1% and 43.2%, respectively. The available N, available P, available K, and water content were positively correlated to SOC, TN, and TP in 0-10 cm and 10-20 cm soil layers. Soil bulk density was negatively correlated to SOC, TN and TP. The alkaline N, available P, available K, and water content were significantly correlated to C/N and C/P in 10-20 cm soil layer. The contents and stoichiometry of soil C, N and P were affected by both ecological restoration measures and soil depth. The shrub-grass intercrop pattern was most beneficial to improve sandy soil environment quality in the study area.

Hydrological functions of litters under five typical plantations in southern and northern mountains of Lanzhou City, Northwest China

LIU Xiao-e, SU Shi-ping

2020, 31(8):  2574-2582.  doi:10.13287/j.1001-9332.202008.019

Asbtract ( 306 )   PDF (808KB) ( 47 )  

Combined with field observation and indoor water immersion test, water holding characteristics of litters from five typical plantations (Platycladus orientalis, Robinia pseudoacacia, Populus alba var. pyramidalis, P. orientalis+R. pseudoacacia, P. alba var. pyramidalis+R. pseudoacacia) in southern and northern mountains of Lanzhou City were examined. Results showed that litter mass under the plantations ranged from 13.50 to 47.01 t·hm^-2, with an order of P. alba var. pyramidalis+R. pseudoacacia＞P. orientalis+R. pseudoacacia＞P. orientalis＞R. pseudoacacia＞P. alba var. pyramidalis. The percentage of un-decomposed litters was greater than that of semi-decomposed litters in all plantations except for P. orientalis plantations. The maximum water-holding rate of litters ranged from 190.8% to 262.7%, with the greatest value in the P. alba var. pyramidalis+R. pseudoa-cacia and the lowest in P. orientalis plantations. The maximum water-holding capacity of litters was 35.29-123.59 t·hm^-2, with an order of P. alba var. pyramidalis+R. pseudoacacia＞P. orientalis+R. pseudoacacia＞R. pseudoacacia＞P. orientalis＞P. alba var. pyramidalis. Litter water absorption rate declined linearly within the first hour, and then decreased slowly. Semi-decomposed litters had a higher water-absorption rate than un-decomposed litters. The maximum water retaining amount and effective retaining amount of the litters were P. alba var. pyramidalis+R. pseudoacacia＞P. orientalis+R. pseudoacacia＞P. orientalis＞R. pseudoacacia＞P. alba var. pyramidalis. P. alba var. pyramidalis+R. pseudoacacia had the highest effective retaining rate. P. alba var. pyramidalis+R. pseudoacacia plantation had highest capacity for soil and water conservation in southern and northern mountains of Lanzhou City.

Effects of water and nitrogen source types on soil enzyme activity and nitrogen utilization efficiency of wheat

SUN Wan, LIU Su-jun, FENG Jian-chao, WANG Peng-tao, MA Dong-yun, XIE Ying-xin, LU Hong-fang, WANG Chen-yang

2020, 31(8):  2583-2592.  doi:10.13287/j.1001-9332.202008.023

Asbtract ( 327 )   PDF (2088KB) ( 53 )  

To provide basis for high-yield and high-efficiency of wheat production, with two wheat cultivars, ‘Zhengmai 366' (strong gluten) and ‘Bainong 207' (medium gluten), we investigated the effects of four nitrogen source types, ammonium chloride (NT₁), calcium nitrate (NT₂), urea (NT₃) and calcium ammonium nitrate (NT₄), applied under two water treatments, no irrigation (W₁) and irrigation at jointing and heading stages (W₂), on soil N-supplying capacity, grain yield and nitrogen utilization efficiency. The results showed that content of soil ammonium and nitrate at flowering stage decreased with increasing soil depths. Compared with the corresponding value of ‘Zhengmai 366' under W₁ treatment, W₂ treatment decreased the contents of soil ammonium and nitrate in the 0-60 cm layer, and enzymes activities of urease, invertase and catalase by 10.0%, 13.3%, 7.5%, 2.8%, and 3.9%, respectively. For the two wheat cultivars, the content of ammo-nium was significantly higher under NT₁ and NT₃ treatments than that of others, while the content of nitrate under NT₂ and NT₃ treatments was significantly higher than that of others. Additionally, NT₃ and NT₄ treatments increased soil urease and invertase activities at the middle and later stages of grain filling. Compared with NT₁ treatment, NT₃ and NT₄ fertilization increased grain yield and nitrogen use efficiency of cultivar ‘Zhengmai 366' by 14.9% and 20.7%, 25.6% and 13.9%, under W₂ treatment, respectively. Soil nitrate content in the 0-20 cm layer and the ammonium content in the 20-40 cm layer were positively correlated with wheat grain yield and nitrogen utilization efficiency. Under both water conditions, applying urea and calcium ammonium nitrate improved soil enzyme activity at the middle and later stages of grain filling, which was beneficial for wheat yield and nitrogen use efficiency.

Effects of water-nitrogen combination on dry matter, nitrogen accumulation and yield of winter wheat

LYU Guang-de, WANG Chao, JIN Xue-mei, XU Jia-li, WANG Rui-xia, SUN Xian-yin, QIAN Zhao-guo, WU Ke

2020, 31(8):  2593-2603.  doi:10.13287/j.1001-9332.202008.029

Asbtract ( 302 )   PDF (1219KB) ( 84 )  

In two growing seasons of wheat (2015-2017), we conducted a field trial with Taishan 28 in Tai'an Academy of Agricultural Science Feicheng experimental base, Tai'an City, Shandong Province. There were four irrigation levels of 150 (A₁), 300 (A₂), 450 (A₃), and 600 (A₄) m³·hm^-2, and four nitrogen application levels of 90 (B₁), 135 (B₂), 180 (B₃), and 225 (B₄) kg·hm^-2. We examined the effects of the combination effects of irrigation and nitrogen on dry matter accumulation and transport, nitrogen accumulation and transport, water consumption and utilization, photosynthetic characteristics, wheat grain yield and yield components of wheat. The results showed that dry matter accumulation, nitrogen accumulation, vegetative organs production, storage and the transportation volume to grains of the dry matter and nitrogen, and dry matter and nitrogen accumulation of grain in the mature stage of wheat all reached the maximum in A₃B₃ treatment, which were significantly different from other treatments. Under all the nitrogen treatments, soil water consumption in the 60-200 cm soil layer was A₃>A₄>A₂>A₁. Water use efficiency and nitrogen use efficiency in A₃B₃ treatment were higher than that under A₃B₄, A₄B₃ and A₄B₄. The net photosynthetic rate, stomatal conductance and transpiration rate of flag leaves from 7 to 28 days after flowe-ring were all significantly higher in A₃B₃ treatment, which was conducive to the photosynthetic synthesis of carbohydrates in wheat. The interaction effect of water and nitrogen addition significantly affected grain yield and yield components. Wheat yield was the highest in A₃B₃ treatment which reached at 9400 kg·hm^-2. In conclusion, the treatment with irrigation of 450 m³·hm^-2 and nitrogen of 180 kg·hm^-2 could significantly improve dry matter and nitrogen accumulation, and promote transportation volume of the dry matter and nitrogen to grain. Compared with the high water and nitrogen treatment, it could effectively increase water use efficiency and nitrogen use efficiency, enhance photosynthetic capacity of flag leaf, produce more carbohydrate, and increase grain yield.

Effects of increased planting density with reduced nitrogen fertilizer application on greenhouse gas emission in double-season rice fields under water saving and simple cultivation mode

ZHOU Wen-tao, LONG Wen-fei, MAO Yan, WANG Bo-ran, LONG Pan, XU Ying, FU Zhi-qiang

2020, 31(8):  2604-2612.  doi:10.13287/j.1001-9332.202008.021

Asbtract ( 317 )   PDF (796KB) ( 56 )  

To clarify the effects of increased density and reduced nitrogen on greenhouse gas emission in double-season paddy fields under the water-saving and simple cultivation mode, we used Luliangyou 996 (early rice) and Fengyuanyou 299 (late rice) as materials to collect greenhouse gas by closed static box method, monitored the dynamics of CH₄ and N₂O emissions from different combinations of increased density and reduced nitrogen for early and late rice, and explored changes in cumulative CH₄ and N₂O emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) as affected by different combinations of increased density and reduced nitrogen from double-season rice fields. The results showed that the cumulative emissions of CH₄ and N₂O from different combinations were significantly different. Compared with the control (CK), cumulative CH₄ emission, GWP and GHGI in the two seasons decreased by 50.8%, 37.3%, and 42.9% for the combination of increased density and reduced nitrogen IR₂(the amount of nitrogen applied of early rice was 86.4 kg·hm^-2, the density was 360000 holes·hm^-2; the amount of nitrogen applied of late rice was 108 kg·hm^-2, the density was 320000 holes·hm^-2), respectively. IR₂ of early rice had the lowest N₂O cumulative emission, being 33.7% lower than CK. IR₁(the amount of nitrogen applied of early rice was 103.2 kg·hm^-2, the density was 320000 holes·hm^-2; the amount of nitrogen applied of late rice was 129 kg·hm^-2, the density was 280000 holes·hm^-2) of late rice had the lowest N₂O cumulative emission, being decreased by 94.9%. IR₂ had the lowest annual total GWP and GHGI of double-season paddy fields. Compared with other treatments of increased density and reduced nitrogen, the IR₂ treatment, where nitrogen fertilizer in both early and late rice was reduced by 28.0%, the density of early rice was increased by 28.6%, and the density of late rice was increased by 33.3%, was an effective and safe option for simultaneously ensuring high yield and reducing greenhouse gas emissions.

Effects of spraying desiccant on dehydration characteristics and grain quality of summer maize hybrids differing in maturity

ZHAO Ji-yu, REN Bai-zhao, ZHAO Bin, LIU Peng, ZHANG Ji-wang

2020, 31(8):  2613-2620.  doi:10.13287/j.1001-9332.202008.030

Asbtract ( 334 )   PDF (1477KB) ( 61 )  

Water content of summer maize hybrids grown in China is too high at harvesting stage, which limits the development of grain mechanical harvesting technology. Spraying the desiccant can regulate physiological process of crop grain filling and reduce water content at harvest. We explored the effects of spraying the desiccant on the dehydration process, grain moisture, and grain quality of summer maize hybrids differing in maturity. Spraying the desiccants reduced dry matter accumulation in different organs of maize, with strongest reduction of middle-late maturity hybrids. Dry matter transfer to the grains of the plants and the harvest index was improved, but with no changes of grain quality. The dehydration rate of grains was positively correlated with the rate of dehydration in diffe-rent organs. The dehydration rate of grains after spraying the desiccants was significantly positively correlated with the rate of dehydration of stems and sheaths. With no negative effects on yield, spraying the desiccant increased the total dehydration rate, shortened the time from flowering to physiological maturity, and increased the time from physiological maturity to harvest, which was beneficial to the further reduction of grain moisture in the later stage. The possibility of grain mechanical harvesting was increased. The economic benefits of spraying the desiccants on mechanical grain harvest of summer maize hybrids differing in maturity were not significantly different from those of ear mechanical harvesting. The economic benefits of middle-late maturity hybrids were higher than those of early maturity hybrids. Spraying desiccant may improve the possibility of grain mechanical harvesting.

Effects of reduced nitrogen application on yield, nitrogen utilization of spring maize and soil nitrate content in Weibei dryland, Northwest China

LIU Peng-zhao, WANG Xu-min, NING Fang, LUO Wen-he, ZHANG Qi, ZHANG Yuan-hong, LI Jun

2020, 31(8):  2621-2629.  doi:10.13287/j.1001-9332.202008.025

Asbtract ( 316 )   PDF (1427KB) ( 91 )  

To get a scientific pattern for nitrogen-reducing and efficiency-increasing production of spring maize in Weibei dryland, we conducted an in-situ field experiment of spring maize (Zhengdan 958 and Shaandan 8806) under dryland farming from 2016 to 2019 in Heyang County, located in Weibei dryland of Shaanxi. There were five nitrogen (N) treatments, including 360 kg·hm^-2(N₃₆₀, a rate commonly adopted by local farm households), 270 kg·hm^-2(N₂₇₀), 150-180 kg·hm^-2(N_150-180), 75-90 kg·hm^-2(N_75-90) and 0 kg·hm^-2(N₀). We investigated the effects of reduced nitrogen application on maize yield, nitrogen uptake and utilization of spring maize and soil nitrate residue. The results showed that: 1) Maize yield of both varieties at N_150-180 was increased by 0.9%-7.1% and nitrogen uptake was decreased by 4.1%-4.6%, while average reco-very efficiency, partial-factor productivity and agronomic efficiency of N at N_150-180 were increased by 79.3%-83.6%, 105.9%-157.7%, and 101.9%-114.1% compared with those at N₃₆₀, respectively. 2) The contents of residual nitrate increased significantly when nitrogen application rate was more than 180 kg·hm^-2, while nitrogen uptake was significantly reduced under rainfall shortage, and thus resulted in increasing soil residual nitrogen. After four-year treatments, the residual nitrate was up to 504.7-620.8 kg·hm^-2 in 0-200 cm soil layer, with a peak in 80-140 cm soil layer. There was a risk of nitrate leaching. According to the comprehensive evaluation for annual yield, nitrogen use efficiency and soil nitrate residue, the optimum N application rate was recommended to be 150-180 kg N·hm^-2 for spring maize in Weibei dryland.

Effects of sub-low temperature and drought stress on water transport and morphological anatomy of tomato plant

XIAO Huai-juan, LI Juan-qi, WANG Ji-qing, DU Qing-jie

2020, 31(8):  2630-2636.  doi:10.13287/j.1001-9332.202008.028

Asbtract ( 421 )   PDF (1925KB) ( 58 )  

We explored the effects of sub-low temperature and drought on water transport in tomato seedlings under normal temperature (25 ℃ day/18 ℃ night) and sub-low temperature (15 ℃ day/8 ℃ night) within the artificial climate chamber, and under normal irrigation (75%-85% field water holding capacity) and drought treatment (55%-65% field water holding capacity). We analyzed the effects of temperature and soil moisture on water transport, stomata and xylem vessel morpholo-gical and anatomical structure of tomato plants. The results showed that compared with condition of normal temperature + normal irrigation, drought treatment significantly reduced leaf water potential, transpiration rate, stomatal conductance, hydraulic conductance, sap flow rate, stomatal length, and diameter of leaf, stem and root conduit, and thus thickened the cell wall and enhanced the anti-embolism ability of conduit in leaf, stem and root. Leaf water potential, transpiration rate, stomatal conductance, hydraulic conductance, and conduit diameter in leaf, stem and root were significantly reduced by sub-low temperature treatment, but the stomata became larger, cell wall was thickened and the anti-embolism ability was enhanced in leaf, stem and root conduit. Under sub-low temperature condition, soil moisture did not affect leaf water potential, transpiration rate, stomatal conductance, hydraulic conductance, stomatal morphology, conduit structure of leaf and root. In conclusion, under drought treatment, the homeostasis in water relationship was obtained by the coordination of leaf, stem and root structure. Under sub-low temperature treatment, the regulation of water relationship was mainly dependent on the changes of conduit structure in leaf and root, which was less affected by soil moisture.

Effects of nitrogen application level on photosynthate distribution of Korla fragrant pear trees

HE Xue-fei, HUANG Zhan, ZHANG Wen-tai, CHEN Bo-lang, ZHOU Yan-hui-zi, CHAI Zhong-ping

2020, 31(8):  2637-2643.  doi:10.13287/j.1001-9332.202008.026

Asbtract ( 305 )   PDF (1084KB) ( 49 )  

Using ¹³C pulsed labeling technique, we examined the biomass and carbon accumulation of different organs as well as the distribution characteristics of ¹³C assimilate of 6-year-old Korla fragrant pear trees under three nitrogen application levels, i.e., 150, 300, and 450 kg N·hm^-2 (marked as N₁, N₂, and N₃, respectively). Results showed that the biomass, carbon accumulation, ¹³C fixation and leaf assimilation capacity of the whole pear tree increased while root to shoot ratio decreased with increasing nitrogen application. Both biomass and carbon accumulation amount of reproductive organs (i.e., fruits) were the highest under N₂ treatment. The ¹³C content and distribution rate of each organ changed dynamically along with increasing nitrogen application. At the new shoot growing stage, leaves and roots had stronger competitive abilities for photosynthate, with ¹³C distribution rates being the highest under N₁ treatment. During fruit swelling and mature stages, leaves and fruits were more competitive, with ¹³C content and distribution rate in leaves being the highest under N₃ treatment and those in fruits being the highest under N₂ treatment. According to the absorption and distribution characteristics of carbon assimilate across organs under the three nitrogen application levels, the optimal nitrogen application level for achieving high fruit yield in the 6-year-old Korla fragrant pear tree orchard is recommended as 300 kg·hm^-2 .

Effects of soil surface electric field on aggregates breakdown and water erosion in black soil region of Northeast China

GUO Wei-zhen, HU Fei-nan, TAN Tao-tao, MA Ren-tian, LIU Jing-fang, LI Zhe, ZHAO Shi-wei

2020, 31(8):  2644-2652.  doi:10.13287/j.1001-9332.202008.022

Asbtract ( 272 )   PDF (1710KB) ( 31 )  

Through quantitatively adjust soil electric field, we investigated the effect of soil electric field on aggregate stability and soil erosion in black soil region of Northeast China with the experiments of wet sieving and rainfall simulation. Results showed that: 1) Soil surface potential absolute value and electric field strength increased with the decreases of electrolyte concentration in bulk solution. Soil electric field strength could reach to 10⁸ V·m^-1. 2) With the increase of soil electric field strength, the degree of fragmentation of soil aggregates increased and the mean weight diameter (MWD) decreased sharply first and then kept constant. 3) With decreasing electrolyte concentration and increasing surface potential, the amount of soil loss increased. As the electrolyte concentration was <0.01 mol·L^-1, the corresponding soil surface potential was > 210 and 209 mV for Bin-xian and Keshan, respectively, the cumulative amounts of soil loss with rainfall time almost overlapped, suggesting that the electrolyte concentration of 0.01 mol·L^-1 was the threshold for soil erosion. 4) There was a linear relationship between soil cumulative loss and MWD. Our results indicated that soil electric field strength increased as the rain enters into the soil, which could induce soil aggregate breakdown and release amounts of fine soil particles. Finally, soil erosion occurred under the driving of flowing water. Our results provided insights into the mechanism underlying soil erosion in the black soil region of Northeast China.

Distribution of exogenous nitrogen fractions and their fate in moss-dominated biological soil crusts

YAO Xiao-meng, XIAO Bo, WANG Guo-peng, LI Sheng-long, TIAN Le-le, SUN Fu-hai

2020, 31(8):  2653-2662.  doi:10.13287/j.1001-9332.202008.024

Asbtract ( 299 )   PDF (1441KB) ( 23 )  

Nitrogen (N) labeled with ¹⁵N was evenly added into plots of moss-dominated biological soil crusts (BSCs) and bare soil on the Chinese Loess Plateau. After that, the surface BSCs and bare soil samples were continuously collected within 1-30 days. The ¹⁵N content of each N fraction in soil, microorganisms, and mosses was measured for each sample. The effects of BSCs on soil N fate and cycling was determined through analyzing the differences in the distribution of ¹⁵N fractions between the BSCs and bare soil. Our results showed that: 1) The ¹⁵N content of total N (TN), microbial biomass N (MBN), and dissolved organic N (DON) in the BSCs was 2.9, 17.5, and 9.0 times higher than that in the bare soil, respectively. The ¹⁵N content of moss plants in the BSCs was 4.73 mg kg^-1. 2) The residual rate of ¹⁵N in the BSCs and bare soil was 13.0% and 3.3%, respectively, indicating that the N fixing and holding ability of BSCs was four times higher than that of bare soil. The percentage of each ¹⁵N fraction in T¹⁵N in the BSCs was in the order of MBN (54.3%)>moss plant N (22.5%)>DON (6.2%), while that in the bare soil was in the order of MBN (11.5%)>DON (2.6%). Over all, microorganisms and mosses in the BSCs had 65.3% higher capacity of N fixation as compared with the bare soil. 3) The transferred amount and storage capacity of MB¹⁵N in the BSCs were 17.2 and 20.5 times higher than that in the bare soil, respectively. Accordingly, the turnover rate of MB¹⁵N in the BSCs and bare soil was 5.8 and 7.2 times per month, respectively, with the turnover time of MB¹⁵N in the BSCs being 1.2 times longer than that in bare soil. In conclusion, BSCs fix and hold more N than bare soil and change the distribution of each N fraction, implying that BSCs play a critical role in N cycling in dryland ecosystems.

Ecological benefits of transfer payment of natural forest protection projects and their impact mechanisms

ZHU Hong-ge, FU Yu-zhu, ZHANG Shao-peng

2020, 31(8):  2663-2670.  doi:10.13287/j.1001-9332.202008.009

Asbtract ( 295 )   PDF (455KB) ( 36 )  

The policy of natural forest protection project (NFPP) is of great significance to the protection and restoration of natural forests. It remains unclear about how to play the role of NFPP transfer payment in forest ecological benefits. Based on panel data of “China Forestry Statistical Yearbook” from 2011 to 2017, we used forest management area and forest tending area as indicators to measure forest ecological benefits, and used spatial lag model and intermediary effect model to analyze the impacts of the transfer payment funds of NFPP on the forest ecological benefits in key state-owned forest areas. The results showed that forest ecological benefits in the key state-owned forest areas in the second phase of NFPP had improved year by year. There was a significant spatial spillover effect of forest ecological benefits of forestry bureaus. The transfer funds of NFPP had a significant positive effect on the ecological benefits of forest resources in key state-owned forest areas. There was a partial intermediary effect between the improvement of human capital and the establishment of first-line management and protection stations. The central government should increase investment in the transfer payment funds of NFPP. Forest administrations should increase the proportion of funds used in improving human capital and establishing first-line management and protection stations.

Correlation of spatial distribution and habitat factors of Firmiana danxiaensis based on GeoDetector

WU Jia-rong, WEI Bao-jing, HU Xi-jun, ZHU Man-le, LI Rui-zhi, FENG Xue-chen

2020, 31(8):  2671-2679.  doi:10.13287/j.1001-9332.202008.018

Asbtract ( 436 )   PDF (4314KB) ( 54 )  

Firmiana danxiaensis is an endemic species of Danxia landform in China. Identifying the main driving factors of its distribution can provide scientific basis for the conservation of F. danxiaensis and related habitats. With GeoDetector, we analyzed the correlation (measured by q value) between the spatial distribution of F. danxiaens and its habitat factors in F. danxiaens Nature Reserve in Nanxiong City and the Guangdong Danxia Mountain Tourism Scenic Area (core scenic area). Factors measured in this study included geographical elements (geomorphological type, soil subtype, elevation, slope, aspect) and climatic elements (annual precipitation and annual sunshine hours, mean annual relative humidity and mean annual wind speed). Our results showed that the main habitat factors affecting the spatial distribution of F. danxiaensis were soil subtype, annual sunshine hours, and geomorphologic genesis type. The q values of those three factors were higher than the mean values of all factors. In the pairwise combination of habitat factors, the interaction between geomorphologic genesis types ∩ annual sunshine hours and soil subtypes ∩ annual sunshine hours was enhanced by two factors and the q value was greater than the mean value of all combinations, with a strong correlation. Compared with other factors, the q value of soil subtypes, annual sunshine hours and geomorphologic genesis types were significantly different in the ecological detection of spatial distribution correlation of F. danxiaensis. The spatial distribution of F. danxiaensis was significantly correlated with soil subtypes, geomorphologic genesis types and annual sunshine hours, indicating that the GeoDetector is a useful method for vegetation habitat factor analysis and species distribution prediction.

Vulnerability assessment of agro-ecological environment in Karst mountain based on set pair analysis model of grey trigonometrically whitening weight

SHU Ying-ge, PENG Wen-jun, ZHOU Peng-peng

2020, 31(8):  2680-2686.  doi:10.13287/j.1001-9332.202008.014

Asbtract ( 215 )   PDF (769KB) ( 21 )  

Ecological vulnerability is a hot issue in the study of global change and sustainable development. Understanding the vulnerability of agro-ecological environment is conducive to rational utilization of regional agricultural resources, which could put forward effective measures for prote-cting agro-ecological environment. Given that the evaluation of agricultural eco-environment vulnerability generally does not consider the relationships among different indicators in different evaluation levels, we used the grey trigonometrically whitening weight set pair analysis (SPA) model to evaluate the vulnerability of agricultural eco-environment in Karst mountain by selecting 11 indicators such as population density, per capita arable land area and per capita afforestation area from the external vulnerability of ecological environment. The results showed that the vulnerability degree of agro-ecological environment in the study area was very high, mainly at the extreme, high and medium vulnerability grades. The proportion of extremely, highly, moderately, mildly and slightly vulnerable areas was 32.4%, 14.1%, 17.7%, 23.6% and 12.2% respectively. This result was consistent with the status of agricultural ecological environment vulnerability in the study area. It was feasible to evaluate the vulnerability of agro-ecosystem with the SPA Model of grey trigonometrically whitening weight, which provided a new method for evaluating agricultural ecological environment vulnerability.

Construction of green space ecological network in Dongting Lake region with comprehensive evaluation method

LI Sheng, LI Tao, PENG Zhong-hua, HUANG Zong-sheng, QI Zeng-xiang

2020, 31(8):  2687-2698.  doi:10.13287/j.1001-9332.202008.012

Asbtract ( 283 )   PDF (4017KB) ( 71 )  

Green space ecological network is important for improving the fragmentation of regional ecological space, biodiversity loss, imbalance of supply and demand in ecosystem services, and ensuring regional ecology. With Dongting Lake region as an example, the ecological sources were evaluated and identified, and basic ecological resistance of grid element was calculated from the perspectives of comprehensive ecosystem service function evaluation, potential biodiversity comprehensive index evaluation and morphological spatial pattern analysis with the support of 3S technology. We corrected the basic ecological resistance by night light index, used the minimum cumulative resistance model to identify ecological corridors, and constructed a weighted evaluation model, eva-luated the degree of aggregation and dispersion of the sources, as well as the contribution of ecological connection of the corridors. Furthermore, we compared and evaluated the structural characteristic index of the integrated networks, the potential “source sink” networks and the planning networks. The results showed that the spatial distribution of the sources was uneven, with forest land, shrubland and wetland acounting for 95.9% of the total area. The Dongting Lake wetland located in the middle of the region was at high ecological risk. The closer the source was to the center of the ecological network system and the smaller the average minimum cumulative resistance was to other sources, the stronger the advantages of aggregation and dispersion. The denser the distribution of medium and high ecological quality sources was around the high ecological quality sources, the higher the aggregation and dispersion. The closer the corridor was to the high ecological quality sources, the greater contribution of ecological connection. Forest land, shrubland, especially river played an important role in connecting natural ecosystem and human social system. The “source-sink” planning greenways formed a supplement to the “source-sink” potential ecological corridors. Compared with the “source-sink” potential network, the α, β, γ and ρ index of the integrated network was increased by 123.1%, 25.8%, 26.2% and 74.6% respectively. Compared with the “source-sink” planning network, the α, β, γ and ρ index was increased by 190.0%, 31.1%, 32.5% and 114.6% respectively. The results could provide reference for the construction of green space ecological network and planning of land use in Dongting Lake region.

Land use change and its driving force on the southern slope of Qilian Mountains from 1980 to 2018

FU Jian-xin, CAO Guang-chao, GUO Wen-jiong

2020, 31(8):  2699-2709.  doi:10.13287/j.1001-9332.202008.017

Asbtract ( 414 )   PDF (4435KB) ( 91 )  

Qilian Mountains is the boundary of the first and second steps of China's terrain, with fragile ecological environment. There is great ecological significance to study land use change and driving force in transitional areas. In this study, we investigated the spatial and temporal characte-ristic of land use and its driving force in the south slope of Qilian Mountains, based on RS image data from 1980 to 2018, with the spatial autocorrelation method, ArcGIS spatial analysis method and principal component analysis. The results showed that, from 1980 to 2018, grassland was the main land use type, and the proportion of construction land was the smallest. Water area and grassland showed a declining trend, while unused land, construction land and farmland showed an increasing trend. There was smaller change for the woodland. The single dynamic degree of different land types decreased following an order of construction land, water, farmland, unused land, woodland and grassland. The comprehensive dynamic degree of land use was 0.9%. The spatial distribution of different land use types showed the characteristics of spatial agglomeration. The increased areas of farmland and the decreased areas of woodland and grassland were mainly distributed in the northwest of the Datong River valley of Menyuan County, while in the upper reaches of Datong River in the northeast of Tianjun County, grassland was occupied by construction land. The driving force of land use was population, science and technology, urbanization, level of economic development, and policies. Our results would support the government to reasonably plan and utilize land resources, which is of significance to the protection of ecological environment and the sustainable development of society and economy on the southern slope of Qilian Mountains.

Deep water leakage from semi-mobile dunes in semi-arid regions and its response to rainfall patterns

WANG Yu-xiang, LIU Ting-xi, DUAN Li-min, TONG Xin, WANG Guan-li, LI Dong-fang

2020, 31(8):  2710-2720.  doi:10.13287/j.1001-9332.202008.011

Asbtract ( 409 )   PDF (2693KB) ( 91 )  

As the main source of soil moisture supply in desertified areas, rainfall has a profound impact on soil moisture changes and plays an important role in deep soil moisture replenishment. Based on the Hydrus-1D model with optimized parameters, we analyzed the dynamic change process of the leakage in the 200 cm deep layer of the semi-mobile dunes in Horqin Sandy Land and its response to the rainfall patterns. The results showed that the averaged leakage replenishment of semi-mobile dunes was 254.31 mm from April to October each year during 2016 to 2019, accoun-ting for 61.8% of the rainfall in the same period. Deep leakage mainly occurred from June to August, accounting for 72.8% of the total. The leakage rate was distributed between 0.03-2.70 mm·h^-1, with the maximum leakage rate occurring under heavy rainfall and frequent rainfall events. The deep soil water supplied by rainfall infiltration was affected by the amount of rainfall, rainfall intensity, duration of precipitation and soil moisture content in the earlier period. Precipitation events with long duration and small rainfall intensity were more conducive to deep water lea-kage, with a significant positive correlation between the leakage and rainfall (R²=0.85). 16-18 mm rainfall was the threshold for the leakage of 200 cm soil depth. The high-frequency rainfall event usually reached peak after 17-38 hours, with the entire leakage process being more than 164 hours. Accurate estimation of deep leakage has theoretical and practical significance for water resource assessment and ecological construction in desertified areas.

Evaluation of the quality of human settlement in downtown Fuzhou based on multi-source data

ZHU Yu-jiao, YAO Xiao-jing, CHEN Wei, HE Zhen-jian, CHEN Liu-jia, YANG Li-na, CHEN Shu-guang, CHI Tian-he

2020, 31(8):  2721-2730.  doi:10.13287/j.1001-9332.202008.016

Asbtract ( 254 )   PDF (3909KB) ( 51 )  

The objective evaluation of human settlement in cities helps find the problems exposed in urban development and make targeted adjustments to improve urban environment. Taking the downtown of Fuzhou as the research area, the residential area as the research unit, using multi-source data such as meteorological monitoring data, remote sensing imagery, map points of interest data (POI), and land planning data, we constructed monitoring system of urban human settlement from four aspects: environmental health and comfort, traffic convenience, city safety, and life conve-nience. The TOPSIS method was used to conduct a comprehensive evaluation of human settlement. The results showed that the human settlement level of downtown Fuzhou was quite different, which was high in the central area and low in the peripheral areas. The human settlement index was high in the middle of the urban area, low in the eastern and southern areas, with mixed high and low values in the western and northern areas. In each index layer, the characteristics of high-high agglomeration and low-low agglomeration of traffic convenience and life convenience were consistent with the distribution of high and low value clusters of the human settlement. Convenient transportation and complete service facilities had a greater impact on human settlement. The environmental health and comfort were characterized by interior low and edge high of the city, while city safety was characterized by interior high and edge low.

Spatio-temporal variation of water yield and its response to precipitation and land use change in the Yellow River Basin based on InVEST model

YANG Jie, XIE Bao-peng, ZHANG De-gang

2020, 31(8):  2731-2739.  doi:10.13287/j.1001-9332.202008.015

Asbtract ( 978 )   PDF (3462KB) ( 357 )  

Yellow River Basin is an important water conservation and ecological barrier area, the study of water supply service in which is of great significance to the high-quality development and ecological environment protection. Based on the Invest InVEST model and the method of scenario analysis, we analyzed the temporal and spatial patterns of water yield in the Yellow River Basin in recent 20 years (1995-2015) with land use and cover, meteorological and soil data as inputs. We examined the impacts of precipitation change and land use change on water yield and their impacts on water yield. The results showed that water yield depth had average growth of 24.34 mm from 1995 to 2015. The high water yield area located in the west and southwest, and the low water yield area located in the northwest. The change of deep spatial pattern was not evident. Among the three grade basins in the Yellow River Basin, the river basin above Longyangxia, with the highest water yield of about 11.7 billion m³·a^-1, was the main water yield area of the Yellow River Basin. The river basin from Lanzhou to Hekou had the lowest water yield, with a value of 44 million m³·a^-1. The average water yield depth of permanent glacier and snow land was the largest in the whole basin. Grassland was the main contributor to the total water yield of the whole basin, providing 62.6% of the total water yield. Land use/cover change had moderate effect on water yield.

Comparison in cadmium accumulation capacities of different leafy vegetables through cadmium-rich substrate cultivation

GAO Xin, ZENG Xi-bai, CHEN Qing, BAI Ling-yu, SHAN Hong, WU Cui-xia, SU Shi-ming

2020, 31(8):  2740-2748.  doi:10.13287/j.1001-9332.202008.039

Asbtract ( 270 )   PDF (1112KB) ( 46 )  

To acquire a feasible method for a rapid comparison of the cadmium (Cd) accumulation capacities of different leafy vegetables, using substrate cultivation with different contents of Cd and cultivation time, we compared the observed Cd accumulation capacity with these obtained in the field. The results showed that the Cd content and bio-concentration factors (BCFs) value in the aboveground tissue of leafy vegetable varied significantly with Cd content and cultivation time. Multi-factor analysis of variance showed that vegetable variety, cultivation time, Cd content in substrate and their interaction had significant effects on BCFs of Cd in leafy vegetable. Leafy vegetable variety was the dominant factor affecting BCFs of Cd in leafy vegetable and controlled its absolute level. When Cd content in the substrate reached 1.0 mg·kg^-1 with a cultivation of 10 days, the correlation coefficient of Cd BCFs between the substrate cultivation and field experiments was the highest, with a R² value of 0.90. The results of cluster analysis and one-way ANOVA had the highest consistence with the field results. Comparatively, the substrate cultivation with Cd content of 1.0 mg·kg^-1 and a cultivation of 10 days showed a good reproducibility and stability in reflecting the difference in Cd accumulation capacities of different leafy vegetable varieties. The Cd-rich substrate cultivation could be used to screen the vegetables with low Cd accumulation and also would promote the field application of the vegetables with low Cd accumulation in the Cd-contaminated area of China.

Effects of different tea plantation ages on soil microbial community structure and diversity

YAO Ze-xiu, LI Yong-chun, LI Yong-fu, CHEN Zhi-hao

2020, 31(8):  2749-2758.  doi:10.13287/j.1001-9332.202008.037

Asbtract ( 307 )   PDF (2194KB) ( 185 )  

We investigated the effects of tea plantation age on soil microbial community structure and diversity with surface and subsurface soil samples (0-20 and 20-40 cm) from tea plantation at different ages (0, 20, 25, 38 and 48 years). We analyzed soil bacterial and fungal communities by terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR techniques. The results showed that soil physicochemical properties changed significantly after planting tea. The contents of soil organic carbon, available nitrogen, and available phosphorus increased at first, and gradually decreased with the increases of tea plantation age. The contents of organic carbon and total nitrogen in the topsoil were significantly higher than those in the subsoil. Moreover, soil bacterial community composition varied across tea plantation age. Bacterial diversity index decreased with increasing tea plantation age. The composition and diversity of soil fungal communities did not show a clear relationship with the tea plantation age. Overall, soil bacterial communities was more sensitive to the tea plantation age than fungal communities. With the increases of tea plantation age, the ratio of soil fungi to bacteria showed increasing trend. Soil microbial community in the tea plantation changed from a “bacterial type” with low fungi/bacteria ratio (F/B) to a “fungal type” with high F/B.

Effects of multifunctional plant rhizosphere promoting bacteria on maize growth in black soil areas in Northeast China

CHEN La, MI Guo-hua, LI Ke-ke, SHAO Hui, HU Dong, YANG Jun-peng, SUI Xin-hua, CHEN Wen-xin

2020, 31(8):  2759-2766.  doi:10.13287/j.1001-9332.202008.036

Asbtract ( 377 )   PDF (1046KB) ( 78 )  

The application of microbial fertilizer plays an important role in improving soil restoration and fertilizer utilization. The effects of microbial fertilizer are greatly affected by crop genotypes and ecological conditions. Little is known about the effects of microbial fertilizers on maize production in Northeast China. To develop microbial fertilizer specific to the black soil and the climate characteristics of Northeast China, we isolated five plant rhizosphere-promoting bacteria (PGPR), named as MZ1, MZ2, MZ3, MZ4 and MZ5, with different degrees of biological functions such as IAA synthesis, phosphate-solubilizing, potassium-solubilizing and siderophore-releasing, from the rhizosphere of maize field. The analysis of ecological adaptability showed that those five strains differed in salt resistance, drought tolerance, acid and alkali resistance, pesticide resistance. The 16S rRNA gene sequences analysis showed that the strains MZ1, MZ2, MZ3, MZ4 and MZ5 belonged to the genus of Sphingomonas, Enterobacter, Pseudomonas, Bacillus and Rhizobium, respectively. In maize field experiment with 50% nitrogen fertilizer reduction, the inoculation with MZ1, MZ3 and MZ5 increased grain yield by 19.9%-25.0%. MZ1, MZ3, and MZ5 could be used as microbial fertilizers for maize in Northeast China.

Assessment on ecological integrity of typical lakes, reservoirs and wetlands in Tianjin, China

XU Xiang-qin, CAI Wen-qian, WANG Yan, DAI Dan, LYU Xu-bo, LEI Kun, SUN Ming-dong

2020, 31(8):  2767-2774.  doi:10.13287/j.1001-9332.202008.038

Asbtract ( 345 )   PDF (898KB) ( 44 )  

The ecological health assessment of lakes, reservoirs and wetlands can provide decision-making basis for ecosystem restoration and management. We selected 20 typical lakes, reservoirs and wetlands sampling points in Tianjin, based on physical, chemical, and biological community indicators data (zooplankton, phytoplankton, benthos, fish, large aquatic plants, riparian plants) obtained during the survey from August to September 2018. We constructed an index of ecological integrity (IEI) including physical integrity, chemical integrity, and biological integrity to evaluate their ecological health. The reference points were selected based on three aspects using standardized methods: habitat environmental quality index (QHEI), water quality status, and disturbance of human activities. The analytic hierarchy process was used to calculate the weight of the three indicators. The evaluation results of the ecological integrity of typical lakes, reservoirs and wetlands in Tianjin were finally obtained. The results showed that: 1) Among all the samples, “healthy” points accounted for 5.0%, “good” points accounted for 20.0%, “general” points accounted for 35.0%, “worse” points accounted for 30.0%, and “poor” points accounted for 10.0%. Ecological health status of typical lakes, reservoirs and wetlands in Tianjin was at a general level, with a trend that the west was better than the east with significant spatial differences. 2) Reference points were selected based on the combination of habitat score, water quality conditions, and human activity disturbance. Water quality indicators could reduce subjectivity when selecting reference points and promote the application of ecological integrity evaluation. 3) The applicability verification results showed that IEI could better characterize the health status of each point, and the discrimination efficiency was obvious, which was suitable for evaluating the ecological health of lakes, reservoirs and wetlands.

Beak morphological and growth characteristic of Sthenoteuthis oualaniensis in the northwest Indian Ocean in winter and spring

HE Jing-ru, LU Hua-jie, CHEN Xuan-yu, LIU Kai, WANG Hong-hao, CHEN Xin-jun

2020, 31(8):  2775-2784.  doi:10.13287/j.1001-9332.202008.033

Asbtract ( 298 )   PDF (1679KB) ( 27 )  

Beak is one of the most important hard tissues of cephalopods, and thus is widely used in the study of cephalopod fisheries ecology and fishery resource assessment. With 1009 Sthenoteuthis oualaniensis samples collected by Chinese light falling-net fishery during February to May in the northwest Indian Ocean, we examined the morphologic and growth characteristics of beak. Results of the principal component analysis showed that the upper hood length (UHL), the upper crest length (UCL), the upper lateral wall length (ULWL), the lower crest length (LCL), the lower wing length (LWL) and the lower lateral wall length (LLWL) could be used as the morphological cha-racteristic parameters to examine the morphological changes of the beak. Results of the analysis of covariance (ANCOVA) showed that there were significant differences in the relationships between all of the morphological characteristic parameters and mantel length (ML) for males and females except UCL. There were significant differences in the relationships between all of the morphological characteristic parameters and body weight (BW) for males and females. The relationships between LCL, UCL and ML were optimally described by the linear functions. Power functions were best for UHL, LWL and linear functions were best for ULWL, LLWL for females. The relationships between ULWL and ML were optimally described by power functions, while the logarithm functions were best for UHL, LLWL and LWL for males. The relationships between all of the morphological characteristic parameters and BW were optimally described by the power functions for females, while the logarithm functions for males except the power function for ULWL. Our results provided scientific basis for the research of the fisheries ecology and stock assessment for S. oualaniensis.

Fishway design based on the swimming ability of two Schizothorax species in the Yalung River, China

WANG Yong-meng, LI Zhi-min, TU Zhi-ying, LEI Qing-song, KE Sen-fan, LUO Jia, CHENG Bi-xin, SHI Xiao-tao

2020, 31(8):  2785-2792.  doi:10.13287/j.1001-9332.202008.040

Asbtract ( 341 )   PDF (1188KB) ( 32 )  

To investigate the swimming ability of two Schizothorax species in the Yalung River and provide basic parameters for the studies on fish behavior and the design of fish passage, we exa-mined the induced velocity, critical swimming speed, and burst swimming speed in Schizothorax dolichonema and Schizothorax prenanti with incremental velocity method and the durable swimming speed in S. dolichonema with fixed velocity method. The results showed that the induced velocity of both species increased first and then plateaued with the increases of body length, with the maximum values being lower than 0.2 m·s^-1. The critical swimming speed and burst swimming speed of S. dolichonema were (0.81±0.20) and (1.49±0.26) m·s^-1, respectively, while the relative critical swimming speed and the relative burst swimming speed were (4.90±1.73) and (9.77±1.72) BL·s^-1 (BL: body length), respectively. For S. prenanti, the critical swimming speed and burst swimming speed were (0.73±0.24) and (1.17±0.39) m·s^-1, respectively, while the relative critical swimming speed was (6.88±2.82) BL·s^-1, and the relative burst swimming speed was (11.75±2.77) BL·s^-1. The swimming duration of S. dolichonema was negatively correlated with the flow velocity of 0.7-1.5 m·s^-1, and the relationship between fatigue time (T) and flow velocity (V) was fitted into lgT=-2.52V+5.59. The relationship between expected fishway length (d) and the tolerable maximum average flow velocity (V_{f max}) was accordingly derived to be V_{f max}=-0.17lnd+1.74. Taken together, the fishway targeting S. dolichonema and S. prenanti was recommended to generate the in-channel velocity larger than 0.2 m·s^-1, while the velocity at the entrance and verticle slot should be 0.73-1.67 m·s^-1, and the main-flow velocity in rest pools should be 0.2-0.7 m·s^-1.

Dominant species of cephalopods and their niche characteristics in offshore of northern South China Sea

CAI Yan-cong, SUN Ming-shuai, XU You-wei, LI Jia-jun, HUANG Zi-rong, CHEN Zuo-zhi, YANG Chang-ping, LIU Wei-da, ZHANG Heng

2020, 31(8):  2793-2803.  doi:10.13287/j.1001-9332.202008.031

Asbtract ( 294 )   PDF (2566KB) ( 38 )  

To understand the relationships among dominant species of cephalopods in offshore nor-thern South China Sea, we examined the niche characteristics of these dominant species from both spatial and temporal dimensions using the index of relative importance (IRI), the niche breadth and overlap indices based on fishery resources data from the bottom-trawl survey for four seasons during 2014-2015. The results showed that five dominant species of cephalopods were recorded for four seasons, including Loligo edulis, L. chinensis, L. beka, Sepia esculenta, and L. duvaucelii. The first two species were shared by all seasons. Compared with historical data, the composition of dominant cephalopods species had changed. The cephalopods resource exhibited obvious temporal and spatial variations. Stock density was higher in the sea area extending from the southern Hainan Island to eastern Guangdong Province than that in Beibu Gulf. The seasonal variation was characte-rized by the largest in summer but the smallest in winter. The temporal and spatial niche analysis showed that there was inconsistent in the order between temporal and spatial niche breadths for domi-nant species. L. edulis (1.32) and L. chinensis (3.90) occupied the largest temporal and spatial niche breadths, respectively. The smallest of temporal and spatial niche breadths were shown for S. esculenta (0.98) and L. duvaucelii (2.04), respectively. Though the temporal niche overlap was numerically larger than the spatial niche overlap, both of them had higher values in interspecies among L. edulis, L. chinensis, L. beka, and the lower overlap for the species pairs between L. duvaucelii and other species. The result of correlation analysis suggested that niche breadth exhibited a significant negative correlation with variation in abundance on both temporal and spatial scales. The ecological niche could reflect the tempo-spatial changes of species resource, which enriched the traditional methods of fishery communities.

A review of research on the urban thermal environment effects of green quantity

ZHOU Hong-xuan, TAO Gui-xin, YAN Xin-ye, SUN Jing, WU Yue

2020, 31(8):  2804-2816.  doi:10.13287/j.1001-9332.202008.013

Asbtract ( 444 )   PDF (669KB) ( 94 )  

The regulative function of green quantity in urban thermal environment is an important topic in urban studies. Here, we reviewed the concepts and developments of green quantity, the measurements of green quantity and urban thermal environment, the relevance between green quantity and urban thermal environment, and its implications for urban planning. After summarizing domestic and international research processes, we put forward four prospective directions: 1) improving the methods for three-dimensional investigation of green quantity, 2) developing means for urban thermal environment monitoring and forecasting, 3) establishing an index system for three-dimensional pattern of urban green quantity, and 4) creating three-dimensional analytical methods to quantify the relationship between green quantity and urban thermal environment. It was expected to provide a three-dimensional spatial perspective for exploring the relevance between green quantity and urban thermal environment. It was proposed to deeply examine three-dimensional patterns of urban green quantity, in order to balance urban thermal environment and multiple ecological benefits, and to provide scientific basis for urban green space planning and design, as well as to form theoretical supports for adaptation to climate change and regulation of urban thermal environments.

Current status and research advances of high-temperature hazards in rice

YANG Jun, ZHANG Yi-zhi, HE Hao-hua, LI Ying-chun, CHEN Xiao-rong, BIAN Jian-min, JIN Guo-hua, LI Xiang-xiang, HUANG Shu-e

2020, 31(8):  2817-2830.  doi:10.13287/j.1001-9332.202008.027

Asbtract ( 446 )   PDF (809KB) ( 212 )  

High temperature stress occurs frequently in rice due to global warming. High-temperature hazard during the booting-flowering and grain-filling stages is one of the major factors limiting rice yield and quality. Here, we summarized the occurrence characteristics (identification, classification, region, and time) of high-temperature hazards, and the effects of high temperature on rice growth and development, including physiology, grain yield, and grain quality. Furthermore, we reviewed molecular biology aspects including quantitative trait locus mapping, transcriptome analysis, proteome analysis, and the monitoring, early warning, risk assessment of high-temperature hazards in rice. The defensive measures against high temperature in rice including selecting heat-resistant varieties, improving field management practices and spraying exogenous substances were intensively described. Finally, future research work on high-temperature hazards in rice was prospected to provide the scientific support for rice high-temperature defense, agricultural disaster reduction, and agricultural efficiency improvement.

Research progress on primers and molecular ecology of comammox Nitrospira

GAO Fu-yun, LI Ya-ying, YAO Huai-ying

2020, 31(8):  2831-2840.  doi:10.13287/j.1001-9332.202008.032

Asbtract ( 915 )   PDF (972KB) ( 176 )  

Nitrification is a key process in nitrogen cycling, which has received considerable attention in the research field of soil biochemistry. In 2015, the discovery of complete ammonia oxidizers (Comammox) challenged conventional two-step nitrification perspective, which represented a paradigm shift in the understanding of soil nitrogen cycling. Comammox are a group of microorganisms capable of conducting both steps of nitrification. In this review, we summarized current understan-ding of the molecular ecology of comammox, including specific molecular biomarkers for comammox, phylogenetic and genomic surveys of comammox and particularly the distribution, diversity and ecological significance of comammox in soil. Further studies should focus on: 1) designing specific molecular biomarkers to examine the distribution and diversity of comammox; 2) optimizing cultivation techniques to isolate/enrich comammox cultures and expending our insights into physiological traits of comammox; 3) characterizing their distribution and in situ activities to elucidate the contribution of comammox processes to soil nitrification and their ecological features, which may assist in unco-vering the mechanisms of nitrogen cycling and promote the environmental protection of soil ecosystem.

Review on wetland water level monitoring using interferometric synthetic aperture radar

CHEN Yue-qing, WU Li-li, ZHANG Guang-xin, QIAO Si-jia

2020, 31(8):  2841-2848.  doi:10.13287/j.1001-9332.202008.035

Asbtract ( 421 )   PDF (538KB) ( 52 )  

Water level is an important indicator of wetland hydrological regime. Detection of wetland water levels through interferometric synthetic aperture radar (InSAR) has outstanding advantage, including high spatial resolution, high accuracy, low cost, and high efficiency. We introduced prerequisites for the monitoring of wetland water levels with InSAR, discussed the types of InSAR techniques, the influencing factors for monitoring wetland water levels and their advantages and disadvantages. There are three prerequisites for effectively detecting wetland water levels with InSAR techniques: 1) the presence of emergent aquatic plants; 2) the main backscattering mechanism is double bounce scattering; and 3) the interferometric coherence exceeds a certain threshold. Current water level monitoring techniques have been developed from traditional InSAR techniques to advanced InSAR techniques, such as STBAS, MM, and DSI. These techniques evolve from detecting relative water level changes to estimate absolute water level and water depth time series. The influencing factors of InSAR techniques for monitoring wetland water levels include operating para-meters of the synthetic aperture radar (SAR) and characteristics of the wetlands themselves. Finally, we proposed the key directions for future research in this field: i) investigating the potential use of specific water level monitoring techniques in other regions with different backscattering and interferometric coherence characteristics; ii) developing new algorithms to integrate multi-sensor, multi-track, multi-band, multi-polarization, and multi-temporal InSAR repeat-pass observation; iii) considering alternative sources of SAR data; and (iv) strengthening research on “by-products” of wetland water level monitoring with InSAR, such as wetland hydrological connectivity, flow direction, and flow regime.