Table of Content

18 June 2010, Volume 21 Issue 06

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Articles

Effects of eco-protection policy on land use/cover in upper reaches of Minjiang River.

2010, 21(06):  1351-1358. 

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By using CLUE-S model, a scenario analysis was made on the land use/cover change in the upper reaches of Minjiang River from 2000 to 2020,based on the historic development trend and the regulations of policies “natural forest protection” and “grain for green”. In 2000-2020, according to the historic development trend, the forestland area (landscape matrix) in the study region would have a continual decrease while the shrub land and grassland areas would be increased, and the landscape pattern would be more fragmental. The implementation of the policies “natural forest protection” and “grain for green” would effectively increase forestland area, being able to reverse the trend of landscape fragmentation and more optimize the landscape pattern.

Simulation of above ground biomass in Larix olgensis plantation.

2010, 21(06):  1359-1366. 

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By the method of harvesting sampling trees, the information of aboveground biomass in 34 plots of a Larix olgensis plantation were collected, of which, the information from 29 plots was selected and fitted with stand factors and TM image RS factors, respectively to establish biomass models, and the information from the rest 5 plots was used to verify the models accuracy. The aboveground biomass in the Larix olgensis plantation could be linearly fitted with either stand factors or RS factors. For the young-middle aged trees, the estimation accuracy of stand factors model was higher(P_stand=94.33%), and the test error was smaller (MRE_stand=6%), compared with RS factors model (P_RS=92.32%, MRE_RS=31%). If only the middleaged trees were taken into account, the estimation effect of the two models had no significant different (error sum E^_stand=329.9 t, E_RS=313.6 t). Overall, the stand factors model was better for the estimation of Larix olgensis cortex, wood, and stumpage biomass, while the RS factors model was better for the estimation of middle-aged trees leaf, flower, fruit, branch, and crown biomass.

Dynamic changes of Robinia pseudoacacia sap flow in hillygully region of Loess Plateau.

2010, 21(06):  1367-1373. 

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From April 14 to October 10, 2009, the dynamic changes of Robinia pseudoacacia sap flow in the hilly-gully region of Loess Plateau were measured with thermal dissipation probe. Meantime, the photosynthetic active radiation (PAR), air temperature, relative air humidity, water vapor pressure deficit (VPD), wind speed, and rainfall were monitored. The diurnal variation of the sap flow velocity (SFV) displayed a singlepeak curve, but the pattern varied among different months. In April, the sap flow started to increase at about 12:00, and reached the peak at about 18:00. From May to August, the sap flow started to increase at 5:30—7:30, and reached the peak at about 15:00. In September and October, the sap flow started to increase at about 8:00, and reached the peak at 11:30—13:00. The monthly average SFV was the highest in August and the lowest in April, with the value being 0.002610 cm·s^-1 and 0.000549 cm·s^-1, respectively. During the monitoring period, the sap flow velocity was significantly correlated with PAR, air temperature, VPD, wind speed, and air relative humidity, and the correlation coefficients declined in the order of air temperature>VPD>PAR>relative humidity>wind speed. The sap flow velocity could be estimated by the linear equation with variables PAR and VPD, and the regression coefficients were highly significant.

Effects of acid rain stress on Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth.

2010, 21(06):  1374-1380. 

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A pot experiment was conducted to study the Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth in different seasons under simulated acid rain stress (heavy, pH=2.5; moderate, pH=4.0; and control, pH=5.6). In the same treatments, the leaf relative chlorophyll content(SPAD), maximum PSⅡ photochemical efficiency (F_v/F_m), actual PSⅡ photochemical quantum yield (Φ_PSⅡ), plant height, and stem diameter in different seasons were all  in the order of October>July>April>January. In the same seasons, all the parameters were in the order of heavy acid rain>moderate acid rain>control. The interactions between different acid rain stress and seasons showed significant effects on the SPAD, F_v/F_m, plant height, and stem diameter, but lesser effects on Φ_PSⅡ， q_P and q_N.

Forest recovery state in wind disaster area of Changbai Mountains, Northeast China.

2010, 21(06):  1381-1388. 

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Based on the field investigation in windfall areas of Changbai Mountains, this paper studied the community recovery characteristics of broad-leaved Korean pine forest (BKPF), spruce fir forest (SFF), and Erman’s birch forest (EBF) that were disturbed by wind disaster 23 years ago. The recovery rate of these three forest types was in the order of BKPF>SFF>EBF, and their total community index was 0.49, 0.44, and 0.33, respectively. The effects of the wind disaster on the forest tree species composition and diversity were different. In BKPF, the total number of trees increased significantly, but the tree species number and α diversity index had no significant change; in SFF, only the Shannon diversity index and Simpson dominance index decreased significantly; while in EBF, all diversity indices except Pielou evenness index had significant decrease. The responses of dominance tree composition and regeneration to the wind disaster depended on forest types. Comparing with the plots not suffered from wind disaster, the BKPF under wind disaster disturbance had greatly different dominance tree compositions, but the difference in both SFF and EBF was not significant. The BKPF’s sapling regeneration was fairly good, while the SFF’s was small, and EBF almost had no sapling regeneration. All the results suggested that the effects of wind disaster disturbance on the test forest ecosystems in study areas was not removed even after 23 years, and the recovery of forest after wind disaster disturbance needs a relatively long time.

Effects of saline-alkali and drought stress on seed germination and TvNHX1 expression of Tripolium vulgare.

2010, 21(06):  1389-1394. 

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By applying 40-400 mmol·L^-1 NaCl, 20-200 mmol·L^-1 NaHCO_3, and 5%-30% PEG, this paper studied the effects of saline-alkali and drought stress on the seed germination and Na⁺/H⁺ antiporter gene (TvNHX1) expression of Tripolium vulgare.40-160 mmol·L^-1NaCl, 20 mmol·L^-1NaHCO_3, and 5%-10% PEG-6000 had less effects on the seed germination; while ≥240 mmol·L^-1 NaCl decreased the seed germination rate,  root length, and shoot length (P<0.05), ≥50 mmol·L^-1NaHCO₃  decreased the seed germination rate (P<0.05), 130 mmol·L^-1NaHCO₃ decreased the seed germination potential, root length, and shoot length (P<0.05), and ≥15% PEG delayed the seed germination. TvNHX1transcripts were basically constitutive at germination stage, but their expression increased distinctly at 160 mmol·L ^-1 NaCl, 100 mmol·L^-1 NaHCO₃, and 10% PEG. Under salt and drought stress, the expression of TvNHX1changed inphase with the phenotype change of germinated seeds, suggesting that  TvNHX1 play important roles in the tolerance of  T. vulgare against adversity stress.

Nitric oxide production in Malus hupehensis roots under waterlogging and the effects of exogenous NaNO₃ on this production.

2010, 21(06):  1395-1399. 

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Taking two-year old Malus hupehensis as test material, this paper studied its root nitric oxide (NO) production under waterlogging, and the effects of  exogenous NaNO₃ on this production. Waterlogging for 3-9 days promoted the NOproduction significantly. Within the 12 days of waterlogging, the NO production, nitrite reductase (NR) and nitric oxide synthase (NOS) activities, and malondialchehyche (MDA) content in roots increased first, and decreased subsequently. Under waterlogging, the application of 10 mmol NaNO₃·L^-1 inhibited the increase of MDA content and NOS activity while improved the NR activity significantly. After applying NaNO_3, the root NO production increased in the first three days, but decreased significantly after the 6th day.

Spatiotemporal pattern of alpine grassland productivity in Qiangtang Plateau.

2010, 21(06):  1400-1404. 

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Based on the meteorological data and remote sensing data, and by using vegetation-climate comprehensive model and CASA model, this paper analyzed the climate change trend and the spatiotemporal pattern of alpine grassland potential and actual net primary productivity (NPP) in Qiantang Plateau. In 1955-2004, the mean annual temperature and annual cumulated precipitation in the Plateau increased by 1.37 ℃ and 63 mm, respectively. The climate in the central and eastern parts of the Plateau became warmer and wetter, whereas it was warmer and dryer in the western part. However, the regional climate change did not yet result in grassland degradation. The mean potential NPP of a lpine grassland was in the order of eastern part > central part > western part. From 1982 to 2004, the potential NPP in the central part had the largest increment (0.55 t·hm^-2·a^-1), followed by in the eastern part (0.51 t·hm^-2·a^-1) and western part (0.21 t·hm^-2·a^-1), which was consequent with the spatiotemporal pattern of climate change in the study area. In contrast, the actual NPP in the eastern, central, and western parts in the past two decades was -0.19, -0.03, and 0.20 t·hm^-2·a^-1, respectively. Overgrazing was the main reason of grassland degradation in the central and eastern parts, and the central part was the key layout area for the implement of ‘grazing withdrawal and management of grassland’ project.

Soil water characteristic curves at different soil depths in a broad-leaved Korean pine forest in Changbai Mountains.

2010, 21(06):  1405-1409. 

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The soil water characteristic curves (SWCC) at different soil depths (0-10 cm, loamy; 20-30 cm, side-bleached layer; and 50-60 cm, loess) in a broad-leaved Korean pine forest in Changbai Mountains were measured by dewpoint potential meter. The SWCC at different soil depths showed a trend of fast descending-slow descending-basically stable. The relationship between soil water content and soil water potential could be successfully described by the power function proposed by Gardner et al, and the correlation coefficient was between 0.9239 and 0.9400. The soil water-holding capacity at different soil depths was in the order of 50-60 cm >0-10 cm >20-30 cm, and the decline rate of soil water content along with the decline of soil water potential at different soil depths was in the order of 0-10 cm >20-30 cm >50-60 cm. The desorption curve was located below the absorption curve. A hysteresis between the absorption process and desorption process was observed, and the hysteresis degree was the highest at the depth 0-10 cm, lower at 50-60 cm, and the lowest at 20-30 cm.

Fractal features of soil aggregate structure in slope farmland with different de-farming patterns in south Sichuan Province of China.

2010, 21(06):  1410-1416. 

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By using fractal model, this paper studied the fractal dimension of soil aggregate structure (D) in the slope farmland (CK), its 5-year de-farmed Neosinocalamus affinis plantation (NAP), Bambusa pervariabilis×Dendrocalamopsis oldhami plantation (BDP), Alnus crenastogyne +Neosinocalamus affinis  plantation (ANP), and abandoned farmland (AFL) in south Sichuan Province of China, and analyzed the relationships between the Dand soil physical and chemical properties. In the de-farmed plantations and abandoned farmland, the contents of ＞0.25 mm soil aggregates and waterstable aggregates were increased significantly, compared with those in the slope farmland. The D was 1.377-2.826, being in the order of NAP＜BDP＜ANP＜AFL＜CK, and decreased with the increasing contents of ＞0.25 mm soil aggregates and water-stable aggregates. Comparing with CK, de-farming increased the soil natural water content, capillary porosity, and contents of soil organic matter, total N, alkali-hydrolysable N, total P, and total K, and decreased soil bulk density, non-capillary porosity, and aeration porosity. There were close relationships between the fractal dimension of soil aggregate structure and the soil physical and chemical properties. All the results suggested that the de-farming of slope farmland was beneficial to the increase of the contents of ＞0.25 mm soil aggregates and water-stable aggregates, and the enhancement of soil structure stability. The D could be used as an ideal index to evaluate soil fertility, and planting Neosinocalamus affinis  on the de-farming slope farmland was a good measure for the improvement of soil fertility in the research area.

Effects of cropping patterns on photosynthesis characteristics of summer maize and its utilization of solar and heat resources.

2010, 21(06):  1417-1424. 

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In order to investigate the effects of interplanting and direct seeding on the photosynthesis characteristics of summer maize and its utilization of solar and heat resources, two summer maize cultivars (Zhengdan 958 and Denghai 661) were planted in the farmlands of Denghai Seed Co. Ltd in Laizhou City of Shandong Province, with 67500 plants·hm^-2 and three sowing dates. The above-ground biomass, plant growth rate, leaf area index, and net photosynthetic rate per ear leaf were measured to reveal the photosynthesis characteristics of test cultivars. In the meantime, the characters of grain-filling were simulated by Richards’ model, and the solar resource utilization efficiency of the cultivars was calculated, in combining with meteorological data. Comparing with interplanting, direct seeding increased the grain yield by 1.17%-3.33%, but decreased the thousand-grain weight significantly. Growth stages were extended under earlier sowing. The leaf area index and net photosynthetic rate from flowering to 30 d after anthesis were significantly higher under direct seeding than under interplanting, but after then, they decreased faster. Direct seeding induced a higher accumulation of dry matter and a faster plant growth rate before and after flowering. Under direct seeding, the maximum grain-filling rate reached earlier, the starting potential was higher, but the grain-filling period, active grain-filling period, and W_maxwere lower, compared with those under interplanting. Also under direct seeding, the total accumulative temperature and solar radiation during growth period decreased by 150-350 ℃·d and 200-400 MJ·m^-2, respectively, but the solar resource utilization efficiency of grain increased by 10.5%-24.7%. All the results suggested that direct seeding was superior to interplanting for the summer maize production under field condition. In order to enhance solar and heat utilization efficiency and excavate yield potential, it would be essential to improve the leaf photosynthesis efficiency and postpone leaf aging.

Photosynthetic rate, transpiration rate, and water use efficiency of cotton canopy in oasis edge of Linze.

2010, 21(06):  1425-1431. 

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The measurement system of Li-8100 carbon flux and the modified assimilation chamber were used to study the photosynthetic characteristics of cotton (Gossypium hirsutum L.) canopy in the oasis edge region in middle reach of Heihe River Basin, mid Hexi Corridor of Gansu. At the experimental site, soil respiration and evaporation rates were significantly higher in late June than in early August, and the diurnal variation of canopy photosynthetic rate showed single-peak type. The photosynthetic rate was significantly higher (P＜0.01) in late June than in early August, with the daily average value being (43.11±1.26) μmol CO₂·m^-2·s^-1 and (24.53±0.60) μmol CO₂·m^-2·s^-1, respectively. The diurnal variation of canopy transpiration rate also presented single-peak type,with the daily average value in late June and early August being (3.10±0.34)mmol H₂O·m^-2·s^-1 and (1.60±0.26) mmol H₂O·m^-2·s^-1, respectively, and differed significantly(P＜0.01). The daily average value of canopy water use efficiency in late June and early August was (15.67±1.77) mmol CO₂·mol^-1 H₂O and (23.08±5.54) mmol CO₂·mol^-1 H₂O, respectively, but the difference was not significant (P＞0.05). Both in late June and in early August, the canopy photosynthetic rate was positively correlated with air temperature, PAR, and soil moisture content, suggesting that there was no midday depression of photosynthesis in the two periods. In August, the canopy photosynthetic rate and transpiration rate decreased significantly, because of the lower soil moisture content and leaf senescence, but the canopy water use efficiency had no significant decrease.

Effects of exogenous nitric oxide on active oxygen metabolism and photosynthetic characteristics of tomato seedlings under cadmium stress.

2010, 21(06):  1432-1438. 

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A hydroponic experiment was conducted to study the effects of exogenous sodium nitroprusside (SNP), a NO donor, on the active oxygen metabolism and photosynthetic characteristics of tomato (Lycopersicon esculentum Mill.) seedlings under Cd stress. The results showed that under the stress, applying 100 μmol·L^-1 SNP promoted the activities of plant superoxide dismutase (SOD) and catalase (CAT) significantly, increased the leaf- and root calcium (Ca) and iron (Fe) contents and the leaf chlorophyll content, net photosynthetic rate (P_n), transpiration rate (T_r), and stomatal conductance (G_s), and decreased the contents of H₂O₂ and MDA and the concentration of intercellular CO₂ (C_i). The addition of hemoglobin, a NO scavenger, eliminated the effects of SNP, while applying 100 μmol·L^-1sodium nitrate or nitrite (the decomposition products of NO or its donor SNP) or 100 μmol·L^-1 sodium ferrocyanide (an analog of SNP) had no significant alleviation effects on Cd stress. This study suggested that exogenous NO could promote the scavenging of reactive oxygen, keep the mineral nutrition in balance, and alleviate the damage of Cd stress to the leaf photosynthetic apparatus, making the tomato seedlings preserve their photosynthetic efficiency.

Impacts of root-zone hypoxia stress on muskmelon growth, its root respiratory metabolism, and antioxidative enzyme activities.

2010, 21(06):  1439-1445. 

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By using aeroponics culture system, this paper studied the impacts of root-zone hypoxia（10% O₂ and 5% O₂）stress on the plant growth, root respiratory metabolism, and antioxidative enzyme activities of muskmelon at its fruit development stage. Root-zone hypoxia stress inhibited the plant growth of muskmelon, resulting in the decrease of plant height, root length, and fresh and dry biomass. Comparing with the control (21% O₂), hypoxia stress reduced the root respiration rate and malate dehydrogenase (MDH) activity significantly, and the impact of 5% O₂ stress was more serious than that of 10% O₂ stress. Under hypoxic conditions, the lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and the malondialdehyde (MDA) content were significantly higher than the control. The increment of antioxidative enzyme activities under 10% O₂ stress was significantly higher than that under 5% O₂ stress, while the MDA content was higher under 5% O₂ stress than under 10% O₂ stress, suggesting that when the rootzone oxygen concentration was below 10%, the aerobic respiration of muskmelon at its fruit development stage was obviously inhibited while the anaerobic respiration was accelerated, and the root antioxidative enzymes induced defense reaction. With the increasing duration of hypoxic stress, the lipid peroxidation would be aggravated, resulting in the damages on muskmelon roots, inhibition of plant growth, and decrease of fruit yield and quality.

Effects of cinnamic acid and vanillin on grafted eggplant root growth and physiological characteristics.

2010, 21(06):  1446-1452. 

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Choosing Solanum torvum as rootstock and cultivated Xi'anlü eggplant as scion, a pot culture experiment was conducted to study the effects of autotoxic substances (cinnamic acid and vanillin) on the root growth, antioxidase activity, and osmoregulation substances content of grafted eggplant, own-rooted eggplant, and rootstock eggplant. Cinnamic acid and vanillin had allelopathic effects on the root system of test eggplants, with low concentration promoting and higher concentration inhibiting the root growth and physiological metabolism. For own-rooted eggplant, the critical concentration of cinnamic acid and vanillin for promotion or inhibition was 0.1 mmol·kg^-1and 0.5 mmol·kg^-1, respectively; whereas for grafted and rootstock eggplants, it was 0.5 mmol·kg^-1 and 1 mmol·kg^-1, respectively. The root resistance to autotoxic substances was in the order of rootstock eggplant > grafted eggplant > own-rooted eggplant. Higher concentration cinamic acid (0.5-4 mmol·kg^-1) and vanillin (1-4 mmol·kg^-1) enhanced the SOD enzyme activity and the proline and soluble sugar contents of grafted eggplant root by 8.50%-24.50%, 9.39%-27.64%, and 12.77%-81.81%, respectively, compared with own-rooted eggplant. The soluble protein content, fresh mass, dry mass, and root activity of grafted eggplant roots were significantly higher than those of own-rooted eggplant, suggesting that grafted eggplant had a strong resistance of rootstocks to autotoxic substances, which alleviated the negative effect of autotoxic substances on root growth.

Effects of long-term fertilization on reddish paddy soil quality and its evaluation in a typical double-rice cropping region of China.

2010, 21(06):  1453-1460. 

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In order to quantify the effects of 27 years application of chemical fertilizers, pig manure, and rice straw on the reddish paddy soil quality in double rice cropping region, the indices of soil bulk density, porosity, maximum water holding capacity, normalized mean weight diameter, pH, cation exchange capacity, available nutrients, organic matter, microbial biomass C, enzyme activities, and rice yield were selected as the evaluation indicators, and classified into four functional groups, i.e., resistance to physical degradation, plant nutrients supply and storage, resistance to biochemical degradation, and sustaining of crop productivity. The soil quality index (SQI) was calculated based on the four functional groups. The results showed that the SQI ranged from 0.544 in treatment CK to 0.729 in treatment NPK plus rice straw. Treatments PK, NP, and NK induced soil degradation, compared to treatment NPK. The deficiencies of soil P and K were the main limiting factors for the double rice productivity in reddish paddy soil area. Even though 30 t·hm^-2·a^-1of pig manure and 4.2 t·hm^-2·a^-1 of rice straw were applied, the soil P and K were still not adequate for the requirement of rice growth. There was no obvious effect of long-term application of lime on the reddish paddy soil quality. The combined application of NPK with organic manure was an important and effective measure in improving soil quality in double rice cropping regions of Southern China.

Effects of planting system on soil and water conservation and crop output value in a sloping land of Southwest China.

2010, 21(06):  1461-1467. 

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A three-year experiment was conducted to study the effects of wheat/maize/soybean with total no-tillage and mulching (NTM), wheat/maize/soybean with part no-tillage and part mulching (PTM), wheat/maize/soybean with total tillage without mulching (TWM), and wheat/maize/sweet potato with total tillage without mulching (TWMS) on the soil and water conservation, soil fertility, and crop output value in a sloping land of Southwest China. The　average soil erosion amount and surface runoff of NTM were significantly lower than those of the other three planting systems, being 1189 kg·hm^-2and 215 m³·hm^-2, and 10.6% and 84.7% lower than those of TWMS, respectively. The soil organic matter, total N,  available K and available Ncontents of NTM were increased by 15.7%, 18.2%, 55.2%, and 25.9%, respectively, being the highest among the test planting systems. PTM and TWM took the second place, and TWMS pattern had the least. NTM had the highest annual crop output value (18809 yuan·hm^-2) and net income (12619 yuan·hm^-2) in three years, being 2.2%-20.6% and 3.8%-32.9% higher than other three planting systems, respectively. In a word, the planting system　wheat/maize/soybean was more beneficial to the water and soil conservation and the improvement of soil fertility and crop output value, compared with the traditional planting system wheat/maize/sweet potato.

Numerical evaluation of soil quality under different conservation tillage patterns.

2010, 21(06):  1468-1476. 

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A 9-year field experiment was conducted on the Guanzhong Plain of Shaanxi Province to study the effects of subsoiling, rotary tillage, straw return, no-till seeding, and traditional tillage on the soil physical and chemical properties and the grain yield in a winter wheat-summer maize rotation system, and a comprehensive evaluation was made on the soil quality under these tillage patterns by the method of principal components analysis (PCA).Comparing with traditional tillage, all the conservation tillage patterns improved soil fertility quality and soil physical properties. Under conservative tillage, the activities of soil urease and alkaline phosphatase increased significantly, soil quality index increased by 19.8%-44.0%, and the grain yield of winter wheat and summer maize (expect that under no till seeding with straw covering) increased by 13%-28% and 3%-12%, respectively. Subsoiling every other year, straw- chopping combined with rotary tillage, and straw-mulching combined with subsoiling not only increased crop yield, but also improved soil quality. Based on the economic and ecological benefits, the practices of subsoiling and straw return should be promoted.

Effects of long-term fertilization on paddy soils organic nitrogen, microbial biomass, and microbial functional diversity.

2010, 21(06):  1477-1484. 

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Soil samples were collected from the plow layers at two long-term experiment sites in Xinhua and Ningxiang counties of Hunan Province, China to study the effects of long-term fertilization on  organic nitrogen, microbial biomass, and microbial functional diversity of paddy soils. Long-term fertilization showed great effects on the soil N content. Compared with CK, treatments NPK plus manure or straw increased the contents of soil total acid-hydrolysable N and its fractions amino sugar N, amino acid N, and ammonium N. Treatment NPK had no significant effects on soil microbial biomass C and N, but trea tments NPK plus manure  increased the contents of soil microbial biomass C and N significantly. BIOLOG test showed that treatments NPK plus manure  enhanced the carbon utilization efficiency of soil microbes, and improved the  functional diversity of soil microbial communities, compared with CK. Long-term different fertilizer treatments resulted in the differences of carbon substrate utilization patterns of soil microbial communities.

Responses of black soil’s microbial respiration and community functional diversity to temperature.

2010, 21(06):  1485-1491. 

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Black soil samples were collected from Lishu (43°20′ N, 124°28′ E), Dehui (44°12′ N, 125°33′ E), Hailun (47°26′ N, 126°38′ E), and Bei’an (48°17′ N, 127°15′ E), and an incubation test was conducted to study their microbial respiration and Biolog metabolic functional diversity at 4 ℃, 15 ℃, and 28 ℃. The soil microbial respiration rate was in the order of Bei’an >Hailun >Dehui >Lishu, irrespective of incubation temperature, but the sensitivity of the respiration to the temperature, i.e., Q₁₀ value, differed. The average value of the Q₁₀for the soils from Lishu, Dehui, Hailun, and Bei’an was 2.72, 3.26, 3.21, and 3.74 in the range of 4 ℃-15 ℃, and was 3.29, 2.36,2.11, and 1.79 in the range of 15 ℃ to 28 ℃, respectively. The metabolic quotient (qCO₂) also differed with incubation temperature, which was in the order of Lishu > Dehui > Bei’an > Hailun at 28 ℃ and of Bei’an > Dehui > Hailun > Lishu at 15 ℃, but no significant difference was observed at 4 ℃. Biolog test showed that the substrate richness and metabolic Shannon diversity index of microbial community were higher for the soils from Hailun and Bei’an at 4 ℃, but higher for those from Lishu and Dehui at 15 ℃ and 28 ℃. Principal component analysis with Biolog data suggested that the metabolic function of soil microbial community was similar between Bei’an and Hailun, and between Dehui and Lishu. In sum, the responses of black soil’s microbial respiration and community functional diversity to temperature varied with latitude, i.e., more sensitive to low temperature in high latitude region, but more sensitive to high temperature in low latitude region.

Effects of conservation tillage on the composition of soil exchangeable base.

2010, 21(06):  1492-1496. 

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Taking the soil in Zhangwu County of Liaoning Province as test object, a comparative study was made to understand the composition of soil exchangeable base under traditional tillage and 6-year conservation tillage (no-tillage plus straw mulch). Comparing with traditional tillage, conservation tillage increased the total amount of exchangeable base (SEB) and the contents of exchangeable K, Ca, and Mg in top (0-15 cm) soil, suggesting its positive effect in increasing soil nutrient holding capacity and buffering ability. This effect had a close relationship with the changes of soil organic matter and clay contents, according to correlation analysis. In addition, the K/SEB and Ca/Mg ratios were higher, while the (Ca+Mg)/SEB, Ca/K, and Mg/K ratios were lower under conservation tillage than under traditional tillage, illustrating that the effects of conservation tillage on soil exchangeable base were mainly presented in the relative enrichment of soil exchangeable Ca and K, especially K. Conservation tillage increased the stratification ratio (0-5 cm/5-15 cm and 0-5 cm/15-30 cm) of soil exchangeable K, Ca, and Mg, and SEB, suggesting the increase of the vertical variability of SEB in plough layer.

Spatial distribution pattern of soil nitrogen in croplands at county scale and related affecting factors.

2010, 21(06):  1497-1503. 

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By using geostatistics and GIS, this paper studied the spatial distribution of soil nitrogen in the croplands in Shuangliu County of Sichuan Province, China, and analyzed the related affecting factors. There was a moderate spatial correlation between the contents of total nitrogen (TN) and available nitrogen (AN) in the cropland soils, and the spatial correlation distance was 15480 m for TN and 26980 m for AN. The regions with higher soil TN content were mainly in the north of the County, i.e, Jiujiang and Xinxing towns, while those with lower soil TN content were mainly in the southeast of the County, i.e., Hejiang and Sanxing towns. The soil AN content decreased obviously from north to south. The TN and AN contents in the soils developed from grey alluvium were significantly higher than those developed from purplish rock saprolith and old alluvium. Paddy soil had significantly higher contents of TN and AN than yellow soil and purple soil. Terrain condition affected the soil TN and AN contents to different degree, and hilly region had the lowest contents of soil TN and AN. Paddy fields had significantly higher contents of soil TN and AN, compared with dryland and orchards; and the regions with higher soil nitrogen content were applied with obviously higher amount of Nfertilizer, compared to the regions with lower soil nitrogen content.

Dry matter accumulation in rice aboveground part: Quantitative simulation.

2010, 21(06):  1504-1510. 

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A field experiment with four rice (Oryza sativa L.) cultivars and different nitrogen application rates was conducted, with the dry matter accumulation (DMA) in the cultivars aboveground part measured at their main growth stages. The dynamic model of relative dry matter accumulation (RDMA) was established with the normalized DMA and TEP (product of thermal effectiveness and PAR) from emergence to maturity, and the temporal characteristics of DMA changes was quantitatively analyzed based on the RDMA model. The dynamic changes of the RDMA could be well described with Richards equation, i.e., RDMA=1.0157/(1+e^{3.6329-7.5907×RTEP})^1/0.5574 (r=0.9938). The model was validated with independent field experiment datasets, involving different eco-sites, cultivars, and nitrogen application rates. The RMSE (root mean square error) between the simulated and observed values of DMA at varied RTEP was 0.86 t·hm^-2. According to the two inflexion points of dry matter accumulation rate equation, the whole process of dry matter accumulation could be divided into early, middle, and late phases. The maximum dry matter accumulation rate (AR_max), relative TEP at  AR_max, and relative dry matter accumulation at  AR_maxwere found to be 2.24, 0.56, and 0.46, respectively.

Coupling situation of agriculture-ecology-economic system in Zhifanggou Watershed of Loess hilly and gully region.

2010, 21(06):  1511-1517. 

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Based on the investigations in the Zhifanggou Watershed of Loess hilly and gully region from 1938 to 2007, and the establishment of eco-environmental and socio-economic comprehensive evaluation indices and coupling model, this paper analyzed the coupling situation of the agriculture-ecology-economic system in the watershed. During the study period, the agriculture-ecology-economic system in the watershed had gone through the coupling processes of economic system vs. ecosystem initial regenesis-consumption-promotion-coordination, and of ecosystem vs. economic system primary response-lag behind-recovery-coordination. According to the coupling degree fitting curves and the coupling type classification, the current agriculture-ecology-economic system in the watershed was still in the situation of coupling, and would be well coordinated.

Spatiotemporal variations of vegetation cover in Zhejiang Province and their relations to eco-climatic indices.

2010, 21(06):  1518-1522. 

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This paper studied the spatiotemporal variations of normalized difference vegetation index (NDVI) in Zhejiang Province in 1982-2006, and their relations to the dominant eco-climatic factors in the Province. In the study period, the vegetation cover in the Province had a slowly decreasing trend, and the area with a significant decrease of NDVI occupied 30.71% of the total. There were significant relationships between the eco-climatic indices and the NDVI of the following year. The NDVI was significantly positively correlated with biological aridity/humidity index, and significantly negatively correlated with biological warmth index, suggesting that the increase of humidity could promote vegetation growth, while excessive heat could inhibit the vegetation growth in the study area.

Recognition of landscape characteristic scale based on two-dimension wavelet analysis.

2010, 21(06):  1523-1529. 

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Three wavelet bases, i.e., Haar, Daubechies, and Symlet, were chosen to analyze the validity of two-dimension wavelet analysis in recognizing the characteristic scales of the urban, peri-urban, and rural landscapes of Shenyang. Owing to the transform scale of two-dimension wavelet must be the integer power of 2, some characteristic scales cannot be accurately recognized. Therefore, the pixel resolution of images was resampled to 3, 3.5, 4, and 4.5 m to densify the scale in analysis. It was shown that two-dimension wavelet analysis worked effectively in checking characteristic scale. Haar, Daubechies, and Symle were the optimal wavelet bases to the peri-urban landscape, urban landscape, and rural landscape, respectively. Both Haar basis and Symlet basis played good roles in recognizing the fine characteristic scale of rural landscape and in detecting the boundary of peri-urban landscape. Daubechies basis and Symlet basis could be also used to detect the boundary of urban landscape and rural landscape, respectively.

Reduction effects of agricultural management practices on non-point source pollution in a watershed in Three Gorges Reservoir Area.

2010, 21(06):  1530-1536. 

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Taking a typical watershed in the Three Gorges Reservoir Area (TGRA) as test object, the AnnAGNPS model was used to evaluate the reduction effects of different cropping, different fertilization level, conservation tillage practice (CTP), conservation reserve program (CRP), and conversion of cropland into forestland program (CCFP) on the output of agricultural nonpoint source pollution (NPS) in the watershed. The simulation results showed that different cropping had no significant difference in the effect of reducing sediment yield, but had significant difference in the effect of reducing phosphorus output. Fertilization level had significant effects on the outputs of total nitrogen and total phosphorus. CTP decreased the sediment yield significantly but increased the nutrient output. CRP reduced sediment yield, but had less effect in reducing nutrient output. CCFP reduced both sediment yield and nutrient output significantly. After the implementation of CCFP, the sediment yield output on the croplands with a slope greater than 10° was less than 5 t·hm^-2, and the nutrient output was within the permissible limit.

Feasibility of washing as a remediation technology for the heavy metals-polluted soils left by chemical plant.

2010, 21(06):  1537-1541. 

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Laboratory simulation tests were conducted to examine the effects of different washing reagents (distilled water, HCl, H₃PO₄, oxalic acid, and CaCl₂) in extracting the heavy metals from contaminated soils left by a chemical plant. The effects of reagent concentration, reaction time, and washing time on the washing efficiency were investigated, and the form variation of test heavy metals was determined before and after HCl washing. Distilled water, H₃PO₄, and CaCl₂ could remove less than 1% of most heavy metals, and the highest removal rate was only 3.58%; while 2 mol HCl·L^-1could obtain the highest washing efficiency under the optimal conditions, i.e., soil:liquid ratio was 1:3, reaction time was 1 hour, and the soils were washed twice by HCl solution. The removal rates of Cr, Pb, Zn, Cu, and Cd from test soils were 80.75%, 88.69%, 98.00%, 79.33%, and 95.52%, respectively. Among the washing reagents, HCl could effectively remove all forms of heavy metals.

Species diversity and colony characteristics of bumblebees in the Hebei region of North China.

2010, 21(06):  1542-1550. 

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Based on the 1893 specimens collected from Hebei Province, Beijing City, and Tianjin City in 2005-2009, and the specimens deposited in the Institute of Zoology, Chinese Academy of Sciences, this paper analyzed the species diversity and colony characteristics of bumblebees in the Hebei region of North China. A total of 32 species belonging to 8 subgenera of Bombus- were recorded, with 32 species in Hebei Province, 18 species in Beijing, and 5 species in Tianjin. The bumblebee in Taihang Mountains, Yanshan Mountains, and Bashang Plateau had the highest richness and abundance, and its foodplant included 80 species of 21 families, among which, Compositae, Leguminosae, and Labiatae were most important. Five bumblebee species, i.e., Bombus hypocrita, B. ignitus, B. patagiatus, B. pyrosoma, and B. picipes, had the largest colony, with more than 110 workers, 160 drones, and 30 young queens produced per colony. The success in rearing colonies of each of the 5 species by queens was >50%, demonstrating that these 5 species had the potential to be mass-reared, with important applied value for crop pollination.

Macrobenthic faunal diversity in Xiangshan Bay.

2010, 21(06):  1551-1557. 

Asbtract ( 1985 )   PDF (855KB) ( 749 )  

In order to understand the community pattern and biodiversity of macrobenthic fauna in Xiangshan Bay, an eight cruises survey was made at thirteen stations of the Bay from July 2006 to August 2007, with the dominant species composition, richness, biomass, secondary productivity, and P/B value of macrobenthic fauna investigated, and the species diversity of the macrobenthic fauna analyzed. A total of 123 macrobenthos species were recorded, including 48 species Mollusc, 33 species Crustacea, 12 species fish, 12 species annelid polychaete, 8 species echinoderms, and some coelenterates and nematodes. The dominant species were more concentrated, and the dominance index was higher. The average secondary productivity of the macrobenthic fauna was 16.70 g·m^-2·a^-1, and the average P/B  value was 0.60. There existed distinct variations (P<0.01) in the species richness index (d), evenness index (J), Simpson’s diversity index (D), and Shannon diversity index (H) among different survey stations, and distinct variations (P<0.01) in the indices except evenness index (J) between years.

Characteristics of fish community structure in the central Jiaozhou Bay in spring and summer.

2010, 21(06):  1558-1564. 

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Based on the bottom trawl surveys in central Jiaozhou Bay from March to August 2009, and by using ecological diversity indices and canonical correspondence analysis (CCA), this paper studied the species composition of fish community, and analyzed the species diversity and its relationships with the environmental factors in the Bay in spring and summer. A total of 43 fish species were captured, belonging to 8 orders, 24 families and 38 genera. The number of fish species increased with increasing bottom water temperature. Margalef species richness index was from 2.440 to 2.770, Shannon diversity index was from 1.322 to 2.346, and Pielou evenness index was from 0.416 to 0.771. No significant differences were observed in the diversity indices between spring and summer. The ranks of the species composition and biomass in contiguous months had less change. Bottom water temperature was the most important environmental factor affecting the monthly change of fish species composition.

Compensation of tree water storage for hydraulic limitation: Research progress.

2010, 21(06):  1565-1572. 

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Hydraulic limitation hypothesis considers that water transport resistance and water potential gradient jointly control the stomatal gas exchange and affect the CO₂ intake, and accordingly, affect the tree height growth. This hypothesis provides a reasonable explanation for the differences of maximum tree height and of height growth patterns in different habits, but has not taken the adapted adjustment of hydraulic architecture and other biological characteristics into account, though the adapted adjustment would drag the increasing water transport resistance to a cetain level. Tree water storage has important biological significance in alleviating the hydraulic limitation of xylem and in controlling the fluctuation of leaf water potential, and is likely the important determinant in stomatal regulation and in the change lattice of water regime. Tree water storage can partially compensate hydraulic limitation. This paper summarized the effects of tree water storage on the hydraulic limitation in the process of tree water use, discussed the possible mechanisms of the compensation of tree water storage for hydraulic limitation and related research methods, and prospected the research directions in future.

Systematic classification and community research techniques of arbuscular mycorrhizal fungi: A review.

2010, 21(06):  1573-1580. 

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Arbuscular mycorrhizal fungi (AMF) are an important component of natural ecosystem, being able to form symbiont with plant roots. The traditional AMF classification is mainly based on the morphological identification of soil asexual spores, which has some limitations in the taxonomy of AMF. Advanced molecular techniques make the classification of AMF more accurate and scientific, and can improve the taxonomy of AMF established on the basis of morphological identification. The community research of AMF is mainly based on species classification, and has two kinds of investigation methods, i.e., spores morphological identification and molecular analysis. This paper reviewed the research progress in the systematic classification and community research techniques of AMF, with the focus on the molecular techniques in community analysis of AMF. It was considered that using morphological and molecular methods together would redound to the accurate investigation of AMF community, and also, facilitate the improvement of AMF taxonomy.

Research advances in denitrogenation characteristics of aerobic denitrifiers.

2010, 21(06):  1581-1588. 

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The discovery of aerobic denitrifiers is the enrichment and breakthrough of traditional denitrification theory. Owing to their unique superiority in denitrogenation, aerobic denitrifiers have become a hotspot in the study of bio-denitrogenation of waste water. Under aerobic conditions, the aerobic denitrifiers can utilize organic carbon sources for their growth, and produce N₂ from nitrate and nitrite. Most of the denitrifiers can also proceed with heterotrophic nitrification simultaneously, transforming NH₄⁺-N to gaseous nitrogen. In this paper, the denitrogenation characteristics and action mechanisms of some isolated aerobic denitrifiers were discussed from the aspects of electron theory and denitrifying enzyme system. The effects of the environmental factors DO, carbon sources, and C/N on the denitrogenation process of aerobic denitrifiers were analyzed, and the screening methods as well as the present and potential applications of aerobic denitrifiers in wastewater treatment were described and discussed.

Field sampling methods for earthworm: A review.

2010, 21(06):  1589-1595. 

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As a critical component of soil ecosystem, earthworm can improve soil structure and relates closely to soil nutrient cycling, playing an important role in promoting soil quality and productivity. However, there is lack of systematic study on the field sampling methods for earthworm, especially in China. This paper reviewed the operational processes of commonly used field sampling methods for earthworm, and discussed their corresponding merits, efficacy, and potential influence on research results. To achieve a complete and accurate characterization of earthworm community size and structure, the method of chemical repellent combined with handsorting could work well at the sites where physical disturbance was acceptable, while the AITC (allyl isothiocyanate) method would be a favorable option at the sites where soil destruction was not feasible.

Effects of parent rock and land use pattern on soil fertility |in Karst region of Northwest Guangxi.

2010, 21(06):  1596-1602. 

Asbtract ( 1973 )   PDF (531KB) ( 823 )  

Taking the soils developed on limestone and sandstone and with typical land use patterns in Karst region of Northwest Guangxi as test objects, this paper studied their soil fertility  under effects of parent rock and land use pattern. A total of eleven soil fertility variables were selected for factor analysis, and the component score for each sampling site was assessed by using principal component analysis (PCA) sequencing and clustering diagram. The factor analysis indicated that the eleven variables could be reduced to four components, i.e., overall soil fertility, soil pH and total phosphorus, soil available phosphorus, and soil total potassium. The PCA sequencing and clustering analysis showed that the overall soil fertility  was mainly affected by land use pattern, being the highest in abandoned farmland. Soil pH and total phosphorus content were mainly affected by parent rock. The pH value and total phosphorus content in the red soil developed on sandstone were much lower than those in the calcareous soil developed on limestone. Soil available phosphorus and total potassium contents were significantly affected by fertilization. The available phosphorus and total potassium contents in Karst calcareous soil and red soil were lower than the average level of China soils. Therefore, the Karst calcareous soil should be fertilized with ammonium nitrogen fertilizer to improve its phosphorus availability, while the Karst red soil should be amended with lime to increase its available phosphorus content. In addition, potassium fertilizer should be applied to the two soil types to improve their soil fertility.

Effects of different rice farming systems on paddy field weed community.

2010, 21(06):  1603-1608. 

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Taking the paddy fields planted with glutinous rice and hybrid rice in the traditional agricultural region in Congjiang County of Guizhou Province as the case, and by using semi-experiment combined with random sampling investigation, this paper studied the characteristics of weed community in the paddy fields under rice monoculture (R), rice-fish culture (R-F), and rice-fish-duck culture (R-F-D). Under the three rice farming systems, glutinous rice had higher capability in inhibiting weeds, compared with hybrid rice. Farming system R-F-D decreased the weed density significantly, with the control effect on  Monochoia vaginalis and Rotala indicabeing 100%. The overall weed-inhibiting effect of R-F-D was significantly higher than that of the other farming systems. Under R-F-D, the species richness and Shannon diversity index of weed community decreased markedly, while the Pielou evenness index increased, indicating that the species composition of weed community changed greatly, and the occurrence of native dominant weed species decreased. It was concluded that R-F-D was a feasible farming system for the control of paddy field weed community.

Characteristics of heat island effect in inner and outer suburbs of Shenyang and the relationships with urbanization.

2010, 21(06):  1609-1613. 

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The monthly, annual, and inter-decade variations of heat island effect in inner and outer suburbs of Shenyang and their relationships with urbanization were analyzed, based on the air temperature data from 1961 to 2008. It was indicated that the monthly and annual heat island effect was higher in inner suburb than in outer suburb, and decreased from inner suburb to outer suburb. The variation trend of monthly heat island effect in inner and outer suburbs was similar from March to November, but in contrary from December to next February, possibly due to the effects of heating in winter. The annual heat island effect in both inner and outer suburbs had an increasing trend before 2000 but a decreasing trend after 2000, and was significantly positively correlated with the green land area, population, and established construction area before 2000 (P<0.05)，but significantly negatively correlated with them after 2000 (P<0.05), the correlation degree being 0.43, 0.52, and 0.26, respectively.

Effects of Cd²⁺concentration on life table demography of Brachionus calyciflorus  under different Scenedesmus obliquus density.

2010, 21(06):  1614-1620. 

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In order to understand the chronic toxicity of a pollutant to an organism in an aquatic environment with different food density, and screen out sensitive endpoints for monitoring Cd²⁺ pollution with rotifers as test animals, this paper studied the effects of different concentration (2.5, 5.0, 10.0, 20.0 and 40.0 μg·L^-1) Cd²⁺ on the life table demography of Bracionus calyciflorus at the Scenedesmus obliquus density being 1.0×10⁶, 3.0×10⁶, and 5.0×10⁶ cells·ml^-1. The results showed that at 25±1 ℃, the 24 h LC₅₀ of Cd²⁺ to  B. calyciflorus  was 37.7 μg·L^-1.  Compared with the controls at the same food density, when the S. obliquus density was 1.0×10⁶ cells·ml^-1, 20.0 and 40.0 μg·L^-1 of Cd²⁺prolonged the generation time of B. calyciflorus significantly, and 5.0 μg·L^-1of Cd²⁺ increased the percentage of  B. calyciflorusmictic offspring. When the S. obliquus density was 3.0×10⁶ cells·ml^-1, the Cd²⁺at all test concentrations except 5.0 μg·L^-1 decreased the percentage of mictic offspring; when the  S. obliquus density was 5.0×10⁶ cells·ml^-1, all test concentration Cd²⁺ had no effects on the life table demography (P>0.05). S. obliquus density had significant effects on the generation time, life expectancy at birth, net reproduction rate, percentage of mictic offspring of B. calyciflorus (P<0.05), Cd²⁺ concentration had significant effects on the generation timeand the percentage of mictic offspring (P<0.05), and the interaction of  S. obliquus  density and Cd²⁺ concentration had significant effects on the percentage of mictic offspring ( P<0.01).  Among all the studied parameters, the generation time and the percentage of mictic offspring were more sensitive to Cd²⁺ pollution under the algal densities of 1.0×10⁶ and 3.0 ×10⁶ cells·ml^-1, with the latter being the most sensitive.