Table of Content

10 September 2017, Volume 36 Issue 9

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Carbon storage, carbon density and spatial distribution of forest ecosystems in Hunan Province.

LIU Xi-qiao1,4, LIANG Meng-jie5, CHEN Long-chi1,3, WANG Si-long1,3*, ZHENG Wen-hui1,4, YU Xin1,4, LI Ren-shan1,4, ZHANG Guang-jie1,4, WANG Fu-sheng2, YANG Hai-jun2

2017, 36(9):  2385-2393. 

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Based on the field investigation and forest resource inventory in 2014, we estimated carbon density, carbon storage and their spatial distribution of forest ecosystems in Hunan Pro-vince. The results showed that the average carbon density of forest ecosystems in Hunan Province was 130.69 t·hm^-2, of which 28.36, 1.77, 0.90, 1.36 and 98.30 t·hm^-2 were in trees, shrubs, herbs, litter, and soil, respectively. Carbon density of vegetation layer and litter layer were positively correlated with that of soil, and the carbon densities of different forest types were found in the following decreasing sequence: broadleaved forest (175.26 t·hm^-2) > Chinese fir forest (136.81 t·hm^-2) > masson pine forest (133.84 t·hm^-2) > Cupressus funebris forest (124.88 t·hm^-2) > bamboo forest (117.29 t·hm^-2) > poplar forest (95.08 t·hm^-2) > economic forest (80.94 t·hm^-2) > slash pine plantation (64.71 t·hm^-2) > shrub (63.73 t·hm^-2). The total carbon storage was 1572.02 Tg C in the forest ecosystems in Hunan Province, of which 341.18, 21.29, 10.78, 16.36, 1182.38 Tg C were in trees, shrubs, herbs, litter, and so il, respectively. The carbon storages of different forest types were found in the following decreasing sequence: broadleaved forest (545.77 Tg C) > Chinese fir forest (419.91 Tg C) > masson pine forest (275.58 Tg C) > bamboo forest (127.76 Tg C) > shrub (74.44 Tg C) > economic forest (71.25 Tg C) > Cupressus funebris forest (25.81 Tg C) > slash pine plantation (22.39 Tg C) > poplar forest (9.11 Tg C). Among 14 cities at prefecture scale, the highest carbon storage (267.43 Tg C) in the forest ecosystem was found in Huaihua, while the lowest (28.12 Tg C) was found in Xiangtan. Spatial distribution of carbon storage was ranked as the order of southwestern Hunan > southern Hunan > northern Hunan > central Hunan. Broadleaved forest, Chinese fir forest, and masson pine forest acted as the main contributor in carbon storage of the forest ecosystems in Hunan Province, accounting for 34.72%, 26.71%, and 17.53%, respectively.

Structural analysis of urban forest communities at different latitudes of the Yangtze River Delta Region.

ZHANG Long1, YAN Jing2, MAO Jia-yuan1, SHI Jiu-xi1*

2017, 36(9):  2394-2402. 

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The structural analysis of urban forest communities can provide a theoretical basis for the construction and development of green cities and forest cities. The main communities of urban forests in Yangtze River Delta Region were surveyed by means of mechanical sampling and representative sampling. The latitude zonality of plant composition, community structure and community characteristics of the urban forests was analyzed. In total, 244 tree species were recorded in the surveyed plots, which belonged to 154 genera and 63 families. The distribution of species was relatively concentrated in urban forests of Yangtze River Delta Region. The top 30 species in the urban background forests and urban manmade forests accounted for 70.1% and 76.66% of total importance values, respectively. The order of species diversity of urban forests at different latitudes was 34°N <32°N <30°N <28°N, the ratio of evergreen trees to deciduous trees showed an increasing trend with decreasing latitude, and the ratio of coniferous to broadleaf species was gradually increased from west to east in the same latitude zone. The community structure of urban forests was simple. The main tree species of urban manmade forests were Platanus × acerifolia and Populus × canadensis in zones of 34°N and 32°N, while it was Cinnamomum camphora in 30°N and 28°N. The composition of tree species varied greatly among different urban background forests. However, the tendency of homogeneity was obvious among different urban manmade forests around Yangtze River Delta Region.

Coverage change of ground and canopy layers in AbiesTsuga forests during the natural regeneration of Bashania faberi.

ZHOU Shi-qiang1*, LI Zhong1, HUANG Jin-yan1, Alan H. TAYLOR2, LIU Dian1, ZHANG Ming-chun1, ZHOU Xiao-ping1, ZHANG He-min1

2017, 36(9):  2403-2411. 

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Arrow bamboo (Bashania faberi) is one of the major staplefood species for wild giant panda (Ailuropoda melanoleuca). In the spring of 1983, massive flowering and dieoff of arrow bamboos occurred in Wolong, Sichuan. The goal of this study is to understand the natural regeneration process of arrow bamboo, a dominant understory species beneath the canopy of AbiesTsuga forests, and the relationship between vegetation layers by analyzing the coverage change during different stages of the regeneration process. We measured the coverage of trees, herbs and moss, and bamboos in seven permanent plots in an oldgrowth AbiesTsuga forest in Wolong National Nature Reserve, Sichuan, China from 1984 to 2013. Arrow bamboo died off in 1983 in six of the seven forest plots. The results showed that, except for two plots, the bamboo coverage in the regenerative bamboo forests was increasing since the dieoff, reaching 60% in 2013. The coverage change of the remnant bamboo forests exhibited a unimodal pattern. The coverage of the herb and moss layers in subsequent years was lower than that of the bamboo dieoff phase in five plots. The results from the KruskaiWallis test revealed a significant difference in canopy coverage between 1984 and 2013; however, the difference of canopy coverage was minor between those two years, ranging from 0.60% to 18.89%. The difference in coverage change patterns among the seven forest plots was mainly related to site conditions. In addition, we also tried to visualize the bamboo coverage across different time periods, which helped to intuitively understand the spatial dynamic patterns of bamboo coverage during the regeneration process of bamboo forest.

Effects of simulated N deposition and burial on Flaveria bidentis litter decomposition and nutrient release.

WEI Zi-shang1,2, LI Hui-yan2, LI Ke-li2, YANG Dian-lin2, HUANGFU Chao-he1,2*

2017, 36(9):  2412-2422. 

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Nowadays, biological invasions and enhanced nitrogen (N) deposition are two key elements of global change; however, their interactive effects on litter decomposition remain unclear. The present study aims to test whether the interactive effects of these two environmental factors on the litter decomposition and nutrient dynamics are stronger than that of each individual factor. A litterbag method was used to examine the effects of simulated N deposition and burial on mass remaining and the dynamics of N, C, and C/N of leaf litters of invasive plant Flaveria bidentis and cooccurring native Setaria viridis during decomposition. Four treatments were set as following: (1) enhanced N deposition (100% enhancement, 28 kg N·hm^-2·a^-1), (2) burial (in 10 cm depth soil), (3) the combined treatment of the two factors (N deposition enhancement + burial), and (4) the control treatment without N addition and burial. Results showed that the litter decomposition constant (k) of F. bidentis leaf litter under simulated N deposition was significantly decreased compared with the control (1.68 vs. 2.26, respectively), while there was little effect of enhanced N on the decomposition of S. viridis leaf litter. In contrast, burial alone or combined with enhanced N deposition tended to significantly enhance the leaf decomposition of both test species. In particular, while the combination of N deposition and burial significantly enhanced N release from F. bidentis leaf litter, N deposition alone did not affect the N release. Under increasing N deposition, litter management option (soil burial or soil surface) may affect the decomposition rate and nutrient dynamics of invasive species litter.

The characteristics of net ecosystem carbon exchange and the contribution of soil respiration during the growing season in sandy grassland.

NIU Ya-yi1,2, LI Yu-qiang1*, GONG Xiang-wen1,2, WANG Xu-yang1,2, LUO Yong-qing1, ZHANG Jian-peng1,2

2017, 36(9):  2423-2430. 

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Based on the eddy covariance system and LI-8150 automatic soil respiration observation system, this present study investigated the characteristics of net ecosystem CO₂ exchange (NEE), the contribution of soil respiration (R_s) to ecosystem respiration (R_eco), and the gross primary productivity (GPP) in Horqin sandy grassland of China. The results showed that the average monthly diurnal variations of NEE changed apparently with a single peak curve; the highest absorption rate (-5.62 μmol·m^-2·s^-1) and the highest release rate (3.14 μmol·m^-2·s^-1) were observed in July. The sandy grassland ecosystem was a carbon sink, with a sequestration amount of 25.85 g C·m^-2 during the growing season. The contribution of R_s to R_eco accounted for 78.39%; the GPP was 275.51 g C·m^-2 and the contribution of R_eco to GPP accounted for 90.62%.

 

Effects of short-term fertilization on soil microorganisms in a mown Leymus chinensis meadow.

DAI Jing-zhong1, YAN Rui-rui2, WEI Zhi-jun1*, BAI Yu-ting1, ZHANG Shuang1, WANG Tian-le1， SUN Shi-xian3

2017, 36(9):  2431-2437. 

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Taking a mown Leymus chinensis meadow in Hulunbuir as the research object, we studied soil microbial response and microbial relationship under different shortterm fertilization treatments by measuring soil microbial quantity, microbial biomass and enzyme activity. Results showed that: (1) Fertilization significantly increased the quantity of soil fungi. With increasing fertilization levels, the quantity of fungi and actinomycetes showed an increasing tendency, but the bacterial quantity decreased. (2) Fertilization significantly increased soil microbial biomass carbon and microbial quotient, while the microbial biomass nitrogen, soil sucrase, urease and catalase were not significantly affected. (3) The soil fungi quantity was significantly positively correlated with soil microbial biomass carbon after fertilization, and the bacterial quantity was significantly positively correlated with the quantity of actinomycetes. (4) Low fertilization level (N 3.5 g·m^-2+P 1.7 g·m^-2) was suitable for the growth of soil microorganisms. A close relationship was found between the soil microorganisms after fertilization. Microbial quantity was the most sensitive to short-term fertilization, secondly was the enzyme activity and microbial biomass. The fungi had more sensitive response to fertilization.

The influences of mixing with Cinnamomum cassia after different cutting intensities in a masson pine forest on soil microbial functional diversity.

YU Su-fang1,2, SHE Guang-hui1, LI Yuan-fa2, CHEN Li-jin3, LI Li-juan2, YE Shao-ming2*

2017, 36(9):  2438-2446. 

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Mixed forests play an important role in improving protective efficiency and stability of forest stands by establishing multilayer or thick-canopy structures. In this study, a 20-year-old masson pine (Pinus massoniana) plantation was harvested with 5 different cutting intensities (clear-cutting, heavy, moderate, light and very light grades), resulting in the canopy closure of 0, 0.4, 0.5, 0.6 and 0.7 respectively. Then cinnamon (Cinnamomum cassia) was planted equally to the quantity of removed masson pine. After the treatments for seven years, the BIOLOGECO method was applied to analyze the soil microbial functional diversity. The results showed that the soil physicochemical properties, AWCD (average well color development) and microbial community functional diversity index in mixed forests were superior to both the masson pine and cinnamon pure stands. The values of abovementioned properties were the lowest in the cinnamon pure stands, while the mixed stands developed from the treatment of light cutting intensity (with a canopy closure of 0.6) had the highest values, being significantly different from those of the masson pine pure stands. The functional diversity of soil microbial communities decreased with the increase of soil depth. Principal component analysis showed that the utilization characteristics of soil microbial carbon sources were not significant among different mixed patterns but obviously different among different forest types, mainly contributed by amino acids, carboxylic acids and sugars. The differences of soil microbial carbon source utilization in different stands were significantly affected by soil water content and organic matter content. Also, other factors such as soil water content, organic matter content, total nitrogen content, total phosphorus content, total potassium content and the ratio of carbon to nitrogen had important impacts on soil microbial community functional diversity. In conclusion, the microbial activity and functional diversity of soil were improved by introducing cinnamon to grow in the masson pine stands, which would offer a reference for transforming masson pines pure forest into mixed forests.

Effects of vegetation type and terrain on vertical distribution of soil organic carbon on abandoned farmlands in the Loess Plateau.

MENG Guo-xin, ZHA Tong-gang*, ZHANG Xiao-xia, ZHANG Zhi-qiang, ZHU Yu-shen, ZHOU Ya, LIU Yi-han, LIN Zhu

2017, 36(9):  2447-2454. 

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Vegetation type and terrain are the main factors affecting the vertical distribution of soil organic carbon (SOC) on regional scale. In this study, the effects of vegetation type and terrain on the vertical distribution of SOC were examined based on field investigation, sample collection and lab analysis in four abandoned farmlands (woodland, shrub land, mixed forest, and grassland) in the Caijiachuan watershed of western Shanxi Province. The results showed that: (1) The SOC contents decreased gradually with the increase of soil depth in the 0-200 cm soil layer. The variation coefficients of each soil layer ranged from 30%-52%. (2) Vegetation type affected the SOC contents significantly to the soil depth of 120 cm, and the SOC contents of the whole profile presented as mixed forest > woodland > shrub land > grassland. (3) Terrain factors showed significant effects on the vertical distribution of SOC. The altitude, slope gradient, slope position and slope aspect had significant effects on the SOC at the depth of 60, 40, 80 and 60 cm respectively. The SOC contents decreased gradually with the increase of slope gradient and slope position, the SOC contents were higher on shady slopes than on sunny slopes, and were higher at the latitude of 1100-1200 m and 1000-1100 m than at >1200 m and <1000 m. (4) The variance component analysis showed that vegetation type, terrain and soil layer explained 66.10%, 22.02% and 11.88% variability of SOC, respectively. Our results had theoretical and methodological significances for evaluating the carbon sequestration benefits of the abandoned farmlands in the loess area.

Distribution and influencing factors of soil organic carbon in Dunhuang Yangguan wetland.

ZHANG Jian1, WANG Li-ping1, XIE Jian-ping2, ZHAO Ting-wei2, CAO Jian-jun1*

2017, 36(9):  2455-2464. 

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Soil carbon storage of wetland ecosystems plays an important role in global carbon budget. In terms of coverage of wetland, three types of sites, including high, medium and low coverage, were sampled in Wowachi herbal marsh wetlands of National Nature Reserve of Dunhuang Yangguan. Soil samples at 0-20, 20-40, 40-60 cm layers were taken from 53 plots to explore the distribution of soil organic carbon (SOC) and its influence factors. The results showed that the SOC concentrations at 0-60 cm depths were 4.94-25.89, 4.77-13.89, and 3.56-11.42 g·kg^-1 at high, medium and low coverage sites, respectively. The differences in SOC at 0-20 cm and 40-60 cm depths were significant between high, medium and low coverage (P<0.05). The spatial variation of SOC was the largest in wetland with high coverage, and it was the smallest in wetland with medium coverage, while it was intermediate in wetland with low coverage. The SOC was positively correlated with soil moisture, total nitrogen, total phosphorus and N:P ratio (P<0.01), but it was negatively correlated with soil salinity and soil bulk density (P<0.01). Soil moisture was the key factor affecting SOC accumulation. Our results can provide scientific basis for wetland protection, management and ecological restoration in this arid region.

Response of soil ciliates community in cold and warm seasons to slope aspects of subalpine meadow in Gannan.

ZHANG Can, LIU Min-xia*, LI Rui, ZHAO Rui-dong, SHAO Peng

2017, 36(9):  2465-2472. 

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In order to reveal the influence of slope aspects on soil ciliates community, the soil ciliates communities and environmental factors were investigated in subalpine meadow of Gannan in April and July of 2015. The results showed that 97 species of ciliates were identified in spring, belonging to 9 classes, 17 orders, 32 families and 50 genera, and 141 species of soil ciliates were identified in summer, belonging to 9 classes, 18 orders, 32 families and 55 genera. Soil ciliate community had obvious surface aggregation. Soil ciliates density and taxa were significantly lower in spring than in summer, and the density of soil ciliates was the highest on the south slope in spring and on the west slope in summer. Soil water content and nutrient content were higher, and pH and soil temperature were lower on the north slope, while the situation was opposite on the south slope, and the environmental factors were moderate on the west slope. RDA analysis showed that the response of soil ciliates was different to environmental factors in subalpine meadows of Gannan. Most of taxa were suitable for the moderate habitat conditions of water, heat and nutrient on the west slope. Nassulidae and Cyrtolophosidae adapted to the condition of rich soil total phosphorus on the southwest slope, while Cohnilemebidae adapted to the condition of high soil water content and rich nutrients on the north slope.

 

Redundancy analysis of leaf traits and environmental factors of alpine meadow in Southern Gansu Province.

LIU Min-xia*, CHE Ying-di, LI Li-rong, JIAO Jiao, XIAO Wei

2017, 36(9):  2473-2480. 

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Understanding ecological implications of plant leaf traits is helpful in exploring community assembly under different environments and thus in revealing the maintenance mechanism of ecosystems. In this study, we measured the stable carbon isotope (¹³C), specific leaf area (SLA), leaf dry matter content (LDMC) and leaf nutrient content of 86 herb species in 25 families along a slope aspect gradient of Southern Gansu alpine meadow, and analyzed correlations between the leaf traits of these plants and environmental factors. The results showed that the soil nutrients and soil water content (SWC) decreased along the northnorthwestwestsouthwestsouth slope aspect gradient, and soil temperature (ST), light illuminance (LI) and pH value increased. Leaf traits also showed strong differences at different slopes. LWC, LPC, SLA, LKC decreased significantly, and LDMC, SPAD and ¹³C values increased significantly along the slope aspect gradient. RDA results showed that LWC, LPC, SLA and LKC were positively correlated with the SWC, soil organic carbon (SOC), total phosphorus (TP), available phosphorus (AP), but negatively correlated with the ¹³C, LDMC and SPAD. Relationships between ST, LI, pH and leaf traits showed the opposite trend, and the contributions of different environmental factors to leaf traits were different. The SWC, TP, ST and pH value were the key limiting factors. The patterns of responses of leaf traits to environmental factors under the conditions of different slope aspects reflect the environmentsl condition and stability of alpine meadow ecosystems.

The photosynthetic characteristics of Ammopiptanthus mongolicus and its affecting factors.

LI Zheng-zhen1, YANG Qiong2, SHI Sha1, FENG Jin-chao1*

2017, 36(9):  2481-2488. 

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In order to provide theoretical reference for the protection and recovery of Ammopiptanthus mongolicus population, the diurnal and seasonal variation patterns of the photosynthetic characteristics in A. mongolicus were investigated by measuring the foliar gas exchange in the field.The results showed that the photosynthesis of A. mongolicus showed significant seasonal variations. In general, the photosynthesis was higher during spring and summer compared with that in fall and winter. The net photosynthetic rate (P_n) in A. mongolicus decreased during 10:00-13:00 from March to September, but its underlying mechanisms were seasonally specific. The results of multiple regression analysis showed that the major physiological factors affecting P_n in A. mongolicus were stomatal conductance, intercellular CO₂ concentration, and stomatal limitation to CO₂. Meanwhile, the environmental factors affecting P_n were air relative humidity, air CO₂ concentration and photosynthetic photon flux density. In conclusion, A. mongolicus grew rapidly during spring and summer, and the main limiting factor of its photosynthesis was the droughtinduced stomatal limitation. It was suggested that the restoration of A. mongolicus population should be conducted during spring and summer, and the protection of A. mongolicus population should be emphasized during drought season and winter.

Effect of genotypic diversity on the growth of Koeleria cristata.

XU Yi-tian, HE Meng-ting, YANG Jing-yi, LI Bing-zhi, WANG Yu-kun, ZHAO Nian-xi*, GAO Yu-bao

2017, 36(9):  2489-2493. 

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Whether  genotypic diversity has  similar ecological function to species diversity is a hot topic in the field of restoration ecology and conservation biology. Many studies about  dominant species have proved that genotypic diversity exhibits similar ecological function to species diversity, but experimental tests about companion species are still lacking. In the present study, we selected Koeleria cristata, a common companion species in the grassland community of northern China, as study object, and examined the effects of genotypic diversity on the performance of above and belowground dry weight, number of tillers at two harvest times. Although all results showed that the combination of 4 genotypes had a better performance than a single genotype, only the belowground dry weight at the first harvest showed a significant difference (P<0.05) between  treatments. The net effect of genotypic diversity was significantly higher than zero for only one variable, the belowground dry weight (P<0.05). Partitioning the net effect of diversity by Loreau & Hector method, the results showed that 9/10 of complementary effect values were positive but not significantly higher than zero (P>0.05), and that 7/10 of selection effect values were negative with the value of aboveground wilted leaf dry weight at the second harvest being significantly lower than zero (P<0.05). As for K. cristata  the selection effect of genotypes did not have any positive effect, and the functional complementarity between genotypes of this species was not as important as that between different species. Therefore, only 1/10 of net effect of diversity was positive, and the proportion  was lower than that obtained from species diversity or genotypic diversity of dominant species. Such information would provide a new perspective for evaluating the ecological function of degraded grassland.

Spatial pattern and interspecific association of Salicornia europaea and Suaeda salsa in Qinwangchuan wetland.

WANG Jian-liang, ZHAO Cheng-zhang*, ZHANG Wei-tao, YAO Wen-xiu, LI Qun

2017, 36(9):  2494-2500. 

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The spatial pattern and interspecific association of plant population are developed as a result of the longterm adaptation and selection of the ecological characteristics of plant population to environmental conditions. The spatial pattern and interspecific association of Salicornia europaea and Suaeda salsa were studied by using phytosociological methods and point pattern analysis in Qinwangchuan National Wetland Park. According to the density of S. europaea, the plots were divided into three density levels: high density (I, >800 plants·m^-2), medium density (II, 400-800 plants·m^-2), and low density (III, <400 plants·m^-2). The results showed that, with the decrease of the density of S. europaea, the plant height and aboveground biomass of S. europaea decreased (P<0.05), while those of S. salsa increased (P<0.05). The S. europaea exhibited clumped distribution from very tiny scale to small scale in Plots I and III, and at all scales in Plots II. The S. salsa exhibited clumped distribution at all scales in Plots I, and from small scale to medium scale in Plots II and III. S. europaea and S. salsa showed negative and no correlations between each other in Plot I (P<0.05), and no correlation in Plot III, and negative to positive correlation in Plot II (P<0.05). The asymmetric competition under the regulatory mechanism of plant density in wetland caused the replacement of dominant species, reflecting the life history strategies of plants in adaption to the environment.

 

Distribution characteristics of nitrogen and phosphorus in waters and release flux estimation in the sediment of Caohai basin, Guizhou.

HAN Zhi-wei1, ZHANG Shui1, WU Pan1*, CAO Xing-xing1,2, TU Han1

2017, 36(9):  2501-2506. 

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Water and sediment samples were collected from Caohai basin. The distribution of nitrogen and phosphorus concentrations in water and the release characteristics of nitrogen and phosphorus from the sediment were analyzed. The results showed that total nitrogen and total phosphorus concentrations of most inflow river water were higher than those of outflow river water during wet and dry seasons. Affected by the exotic input, total nitrogen and total phosphorus concentrations of the waters in emerged plants zone were higher than that of submerged plants zone, which were decreasing along the water flow direction. In wet season, the concentrations of total nitrogen and total phosphorus in sediment interface water were higher than those of surface water, while such a pattern was not obvious in dry season. The release flux of total nitrogen from sediment was between 5.244 and 362.506 mg·m^-2·d^-1, which was considered as “source” of total nitrogen. The release flux of total phosphorus from sediment ranged from -3.081 to 3.009 mg·m^-2·d^-1, which was considered as “sink” in emergent plants zone and “source” in submerged plants zone, indicating that endogenous release is an unneglectable source of nitrogen and phosphorus in Caohai waters.

 

The leaf microstructure of different trees and its impact on air particlescapturing ability.

ZHANG Wei-kang1，2, WANG Bing1,3, NIU Xiang1,3*

2017, 36(9):  2507-2513. 

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Particulate matter (PM), including PM₁₀ and PM_2.5, is one of the major pollutants impacting air quality and public health. Trees can capture the particles and improve the air quality. In this study, we used Atomic Force Microscopy and Scanning Electron Microscope to investigate the leaf surface micromorphological characters of trees in different sites of Beijing, and analyzed the influence of the leaf microstructure of different tree species on capturing air particulate matter. The results showed that different trees had different abilities to capture particles. Coniferous species were found to capture more particles than did broadleaf trees. The particlescapturing ability of leaves was significantly influenced by leaf microstructure (P<0.05). For Pinus tabuliformis and P. bungeana, the particlescapturing ability was mainly impacted by stomatal density, the thickness of waxy layer, epidermis and texture, while leaf roughness was the major factor for other trees, including Salix matsudana, Acer truncatum, Ginkgo biloba, and Populus tomentosa. Leaf surface wettability was negatively correlated to particlescapturing ability (P<0.05).

 

Effect of shallowburied drip irrigation on water consumption characteristics and yield of spring maize in semiarid region of western Liaoning.

GUO Jin-lu1,2, GU Jian1, YIN Guang-hua1*, LI Xue1,2

2017, 36(9):  2514-2520. 

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A microplot field experiment with automatic rain shelter was carried out to study the effect of irrigation quota on water consumption characteristics, grain yield and water use efficiency (WUE) of maize by shallowburied drip irrigation (SDI) in a semiarid region of western Liaoning. The results showed that the water consumption of maize under SDI displayed a fluctuating trend during the whole growth period. The water consumption was larger during the jointing to heading and filling to harvesting stages, and a larger water consumption intensity was observed at the jointing to heading and heading to filling stages. With the increase of irrigation quota, the grain yield of different treatments increased; the increase of 100grain weight and grains per spike were the main reasons for the increase of grain yield. Compared with the conventional furrow irrigation (CFI), SDI with an irrigation quota of 2908.0 m³·hm^-2 reduced the irrigation amount by 30%, the grain yield decreased by only 3.4% (no significant difference), but the water use efficiency (WUE) and irrigation water use efficiency (IWUE) increased by 22.1% and 27.5%, respectively. There was a quadratic parabola relationship between grain yield and irrigation quota. When the irrigation quota was less than 3816.4 m³·hm^-2, the grain yield increased with irrigation quota until the maximum yield 12161.9 kg·hm^-2. However, the grain yield decreased as irrigation quota over 3816.4 m³·hm^-2. With a comprehensive consideration of grain yield, WUE and IWUE, a SDI irrigation quota of 2908.0-3816.4 m³·hm^-2 would be appropriate in the semiarid region of western Liaoning.

Effect of apricot and crop intercropping on yield and land productivity in a semiarid area of Northeast China.

BAI Wei, SUN Zhan-xiang*, ZHENG Jia-ming, DU Gui-juan, CAI Qian, FENG Liang-shan, YANG Ning

2017, 36(9):  2521-2528. 

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A field experiment was conducted in 2012-2014 with seven planting patterns including apricotpeanut intercropping, apricotmillet intercropping, apricotsweet potato intercropping, and sole apricot, sole peanut, sole millet and sole sweet potato cropping, to investigate the effects of apricot intercropping system on crop yield and land productivity. The results showed that there was a significant difference between intercropping and sole apricot systems (P<0.05), and the average yield of peanut, millet and sweet potato in intercropping system was 62.90%, 54.88% and 64.32% lower than that of sole cropping system in the three years studied, but there was no significant difference in the apricot yield between apricot intercropping and sole apricot cropping (P>0.05). Analysis of yield components showed that 100grain weight, dry weight of pods and dry weight of peanut kernel were the major factors decreasing the yield of peanut in intercropping system; spike length, panicle and panicle weight were the major factors decreasing the yield of millet in intercropping system; fresh weight and dry weight were major the factors decreasing the yield of sweet potato in intercropping system. The land equivalence ratio of the apricot intercropping was more than 1.00, which indicated that the three intercropping patterns had obvious advantages. Specifically, the apricotmillet intercropping was better than the other two, and the land productivity of apricotmillet intercropping was 5.15% and 5.93% higher than that of apricotpeanut intercropping and apricotsweet potato intercropping, respectively. The correlation analysis showed that the land equivalent ratio was significantly positively correlated with crop partial land equivalent ratio (r=0.930^**), and negatively correlated with the harvest index (r=-0.299). Collectively, the apricotmillet intercropping can be suitable for the local ecological environment, and has a good application potential in the development of rainfed agriculture in aeolian, sandy semiarid region of Northeast China.

Response of gas exchange parameters of Camellia nitidissima to light intensity.

CUI Zhi-yi1, ZHANG Ning-nan1, YANG Zeng-jiang1*, XU Da-ping1, LIU Xiao-jin1, HONG Zhou1, XIAO Yu2

2017, 36(9):  2529-2534. 

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To investigate the suitable canopy density and light intensity for the cultivation of Camellia nitidissima in the understory planting, the C. nitidissima saplings grown under Dalbergia odorifera with different planting densities, and the C. nitidissima seedlings under shading network of different aperture sizes were chosen as study materials, to study the photosynthetic physiological characteristics of  C. nitidissima. The results showed that the net photosynthesis rate decreased with decreasing the light intensity when the light intensity was below 700 μmol·m^-2·s^-1, stomatal conductance tended to increase at first and then decrease, intercellular CO₂ concentration increased, transpiration rate decreased, and water use efficiency varied nonsignificantly with decreasing light intensity. The correlation of leaf gas exchange parameters showed difference between seedlings and saplings, whereas there was no significant difference in the relationship of net photosynthesis rate with stomatal conductance between seedlings and saplings. The phenotypic plasticity of leaf gas exchange parameters of C. nitidissima saplings was high, being over 0.8. Our results showed that there was photoinhibition observed in C. nitidissima saplings under the light density of 700 μmol·m^-2·s^-1. So we suggest that the cultivation of C. nitidissima in the understory planting should be conducted in forest stands with above 30% canopy density to avoid growth inhibition by light stress.

Response of photorespiration of Glycine max leaves to light intensity and CO₂ concentration.

YE Zi-piao1, WANG Yi-juan2, WANG Ling-li2, KANG Hua-jing2*

2017, 36(9):  2535-2541. 

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The light and CO₂responses of photorespiration rate (R_p) of soybean (Glycine max) leaves were studied under 2% and 21% O₂. The results showed that R_p of soybean leaves increased almost linearly with increasing photosynthetically active radiation (PAR) when PAR was less than 600 μmol·m^-2·s^-1; R_p reached the maximum value of 12.69 μmol CO₂·m^-2·s^-1 when PAR was about 1200 μmol·m^-2·s^-1, and then R_p decreased with increasing PAR. The function relationship between R_p and PAR was constructed. The fitted result showed that the maximum value of R_p (P_pmax) was 13.42 μmol CO₂·m^-2·s^-1, and the light intensity corresponding to P_pmax was 1207.74 μmol·m^-2·s^-1. The fitted values were extremely in agreement with the measured values (P<0.05). As air CO₂ concentration (C_a) (0-1200 μmol·mol^-1) increased, R_p of soybean leaves increased firstly and then decreased. It reached a maximum value of 9.97 μmol CO₂·m^-2·s^-1 when C_a was about 600 μmol·mol^-1. The function relationship between R_p and C_a was also constructed. The fitted result showed that the P_pmax was 10.21 SymbolmA@mol CO₂·m^-2·s^-1, and the C_a corresponding to the P_pmax was 625.74 μmol·mol^-1. The fitted values also accorded with the measured values (P<0.05). Thus, it can be concluded that the constructed function relationships between R_p and PAR and between R_p and C_a would provide a powerful means for the quantitative study of photorespiration of plant leaves.

 

Response pattern of metamorphic tadpoles of Mongolian toad Pseudepidalea raddei to phytohemagglutinin and its ecological significance.

GAO Hui-qing, ZHANG Qiong-wen, SUN Si-qi, LIAN Li-yan, WANG Hong, ZHANG Zhi-qiang*

2017, 36(9):  2542-2548. 

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Different developmental stages of tadpoles of Mongolian toads, Pseudepidalea raddei were identified by Gosner staging tables (Gosner, 1960). 20 μL solution of three concentrations of phytohemagglutinin-P (PHA-P) (1, 2.5 and 5 mg·mL^-1) or equivalent salt was injected in one side or opposite one of lower legs of Gosner 46 tadpoles. The tissue thickness of injected sites was measured prior to injection (0 h), and 3, 6, 9, and 12 h after injection, and an optimal PHA-P concentration was selected. Under the condition of optimal PHAP concentration, the intensity and latency of PHAP response were compared among Gosner 37, 42, 44 and 46 stages of tadpoles. The results showed that Gosner 46 tadpoles did not show significant differences after injection of the three levels of PHA-P, but the peak of PHA-P response appeared at earlier or later time, and 2.5 mg·mL^-1 was considered as the optimal injection dose. The PHA-P response of Gosner 42 tadpoles peaked at 3 h after the injection. The PHA-P response of Gosner 37, 44 and 46 tadpoles peaked at 3-6, 3-9, and 3-12 h after the injection, respectively. The maximal PHA-P response of Gosner 37 tadpoles was higher than that of Gosner 46 tadpoles, but there were no significant differences among Gosner 37, 42 and 44 tadpoles. The patterns of PHA-P response changed with different developmental stages of tadpoles in Mongolian toads. The single peak of PHA-P response was rapid and short in Gosner 42 tadpoles. The peak was delayed in the other aquatic developmental stages, and the intensity of the peak of the PHA-P response declined with prolonged duration in terrestrial tadpoles, which may be related to various environmental conditions on land.

Effect of nitriteN on acute toxicity and nonspecific immune parameters of Palaemonetes sinensis.

BAO Jie1, JIANG Hong-bo1, CHENG Hui1, SHE Qiu-xin1, YU Ye-hui1, LI Xiao-dong1,2*

2017, 36(9):  2549-2555. 

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An acute biological toxicity test of nitriteN (NO₂^--N) on Palaemonetes sinensis (with body weight of 0.28±0.05 g) was carried out in the laboratory at 18±1 ℃ and pH 7.3±0.1. The results showed that the median lethal concentrations of NO₂^--N for 24, 48, 72 and 96 h to P. sinensis were 37.9, 27.3, 24.9, and 23.2 mg·L^-1, respectively, and the safety concentration (SC) for 96 h was 2.32 mg·L^-1. Then the P. sinensis were exposed to five NO₂^--N concentrations (6, 9.5, 13, 16.5 and 20 mg·L^-1) and related nonspecific immunity indicators were measured at 24, 48 and 96 h. After exposure to NO₂^--N for 24 h, no significant difference for superoxide dismutase (SOD) activities in the hepatopancreas and muscles was observed among the different treatments (P>0.05), with the exception of the 20 mg·L^-1 treatment in muscle. At 96 h, the SOD activities in hepatopancreas of the 13, 16.5 and 20 mg·L^-1 groups were significantly lower than that in the control group (P<0.05). In comparison, muscle tissues in the 6 and 9.5 mg·L^-1 groups were significantly higher than that in the control group (P<0.05). At 24 h, there was no significant difference for either acid phosphatase (ACP) or alkaline phosphatase (AKP) activity in hepatopancreas, except that the ACP activity of the 20 mg·L^-1 group and the AKP activity in the 6 mg·L^-1 group were significantly increased. At 96 h, the ACP and AKP activities in the hepatopancreas for the 13, 16.5 and 20 mg·L^-1 groups were significantly decreased. In comparison, after exposure to NO₂^--N for 24 h, the ACP and AKP activities in the muscles showed a “poisonintoxication” effect, and they all increased significantly except the AKP activities in the 13  and 20 mg·L^-1 groups (P<0.05); at 96 h, there was no significant difference among the various treatments (P>0.05) except the 9.5 mg·L-1 group. It was concluded that P. sinensis could tolerate NO₂^--N of relatively high concentrations, but exposure to NO₂^--N for long durations had significant effects on the activities of nonspecific immunerelated enzymes in P. sinensis. Our results provide a better understanding on the healthy aquaculture of P. sinensis.

Acute and chronic toxicity of phenanthrene on Chironous riparius larvae.

DENG Wan-rong1,2, LIU Zhi-hong3, SUN Li-zong1,2, LI Xiao-jun1*, GONG Zong-qiang1, JIA Chun-yun1

2017, 36(9):  2556-2563. 

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According to the guideline of OECD 235 and 218, the toxicity of phenanthrene (Phe) to Chironomus riparius larvae was studied. In the toxicity experiments, survival rate and emergence time were used as endpoints. The acute toxicity (48 h) was assessed by using spiked water and the chronic toxicity (28 d) was assessed by using spiked sediments. The results showed that for acute toxicity, the 24 h and 48 h lethal concentrations to 50% of organisms (LC50) of Phe in water to C. ripurius larvae were 1100 and 337.2  μg·L^-1, respectively. For chronic toxicity, the 28 dLC50 of Phe in sediment and in pore water to C. ripurius were 24.9 mg·kg^-1 and 10.4  μg·L^-1, respectively. Additionally, the mean emergence time of the larvae was advanced with the increasing concentration of Phe in sediments. When the concentration of Phe in sediments increased to 5 mg·kg^-1, the average emergence time of test organisms was significantly earlier than control and lowexposure concentration groups (P<0.05). When the exposed concentration in sediments increased to 10 mg·kg^-1, the average emergence time was 3.8 d shorter than control group, and from 5 mg·kg^-1 on, the average emergence time of different exposure concentrations was similar to each other (3.7-4.2 d).

 

Effects of rising temperature on phyllosphere culturable bacteria of Zostera japonica.

HAN Qiu-ying1,2, ZHANG Ze-yu3, LIU Hong-xia4, LIU Wei-yan5, ZHANG Xiao-li2*

2017, 36(9):  2564-2571. 

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Phyllosphere microorganisms play an important role in physiological metabolism and ecological functions of seagrasses. Little is known about the effects of rising temperature on phyllosphere culturable bacteria of Zostera japonica. The abundance, composition, diversity and distribution of phyllosphere culturable bacteria under 26, 28, 30 and 32 ℃ were studied by isolation, counting, RFLP, sequencing and phylogenetic analysis. The abundance of bacteria under different temperatures showed a pattern of 32 ℃>28 ℃>26 ℃>30 ℃. A total of 363 strains were isolated and divided into 24 OTUs. No common OTU was found across all temperatures. All strains derived from α and γproteobacteria, and Marinomonas was the most dominant phyla, which accounted for 86.8% of total abundance under 28 ℃. Pseudomonas and Thalassospira sharply decreased with rising temperature; Marinobacter and Vibrio were enriched under 30 ℃, while Rhodobacteraceae and Ruegeria sharply increased under 32 ℃. The diversity and evenness of phyllosphere culturable bacteria were much higher under 26 and 32 ℃, while the lowest under 28 ℃.

Effects of different co-metabolic substrates on the decolorization of reactive black 5 by bacteria and the community structure of bacterial flora.

ZHANG Qing-yun1,2, XIE Xue-hui1,2*, YU Cheng-zhi1,2, CHEN Ying1,2, LIU Jian-she1,2*

2017, 36(9):  2572-2580. 

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In this paper, seven types of substrates were used as co-metabolic substrates, the functional bacterial flora DDMZ1 was applied as the initial bacterial flora, and an azo dye, reactive black 5, was chosen as the target pollutant. The effects of different cometabolic substrates (sucrose, glucose, fructose, glucose + fructose, beef extract, peptone, sodium carbonate) on the decolorization performance and community structure of bacterial flora DDMZ1 on decolorization of reactive black 5 were studied by the stationary culture method. Decolorization results showed that added fructose co-substrate promoted bacterial decolorization performance. Under 500 mg·L^-1 of reactive black 5, culturing for 72 h, the decolorization rate reached 88.96%. Highthroughput sequencing analysis results showed that the bacterial community structure significantly differed with different cometabolic substrates. On the classification of genus level, Acinetobacter spp. occupied the leading position in samples with peptone, beef extract and carbonate as co-substrates, whereas contents of Lactococcus spp. and Burkholderia spp. were higher in samples with sucrose, glucose, fructose, glucose + fructose as co-metabolic substrates. Among them, Lactococcus reached its maximum ratio in sample with fructose as co-metabolic substrate, which indicated that Lactococcus might function as an important dominant genus in decolorizing process of reactive black 5. To sum up, compared to the initial flora DDMZ1, organic nitrogen sources and inorganic carbon co-metabolic substrates had little effects on the community structure, while sugars as co-metabolic substrates significantly affected the community structure. Furthermore, fructose was able to enrich Lactococcus as functional decolorizing bacteria, and optimized the bacterial community structure, thus promoting bacterial decolorization effects.

Risk assessment of climate change in Guangxi biodiversity conservation priority areas.

HE Jie-lin*, HUANG Zhuo, XIE Min, ZHOU Mei-li

2017, 36(9):  2581-2591. 

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Based on the historical observations of 48 national meteorological stations in Guangxi biodiversity conservation priority areas from 1961 to 2014, using the linear trend analysis method and climate change index, the climate change characteristics and risks were analyzed. The results showed that the climate tended to be warmer and drier in the biodiversity conservation priority areas as the temperature increased, while the rain days, relative humidity and sunshine hours all decreased. The average annual temperature increase rate was 0.155 ℃·10 a^-1. The decrease rates of annual rain days, relative humidity and sunshine hours were 4.0 d·10 a^-1, 0.7%·10 a^-1, and 4.3 h·a^-1, respectively. The lowtemperature days decreased while hightemperature days increased in some areas. Specifically, the reduction of lowtemperature days mainly occurred in Jiuwan Mountains, Nanling Mountains of Northern Guangxi, and Western Guangxi mountainous areas with primitive forests; the increase of hightemperature days mainly occurred in Western Guangxi mountainous areas with primitive forests, Western Guangxi karst mountainous areas, Daming Mountains, Jiuwan Mountains, and the coastal areas. Meanwhile, the increases of heavy rain days in autumn and winter and severe drought days mainly occurred in Western Guangxi karst mountainous areas, Daming Mountains, and the coastal areas. Among the three typical habitats for biodiversity in Guangxi, the karst areas were mostly affected by climate change, and suffered the greatest risk, followed by the coastal areas and islands. The primeval forest areas in Nanling Mountains of Northern Guangxi were stable in climate and had the lowest risk. More than 95% of the biodiversity conservation priority areas in Guangxi were at the middle or lower levels of risk, except Xilin, which was the only highrisk area.

Emergy accounting on natural graphite and spherical graphite.

YANG Qing1,2, GENG Yong3*, SUN Lun4,5, LIU Zhe6, DONG Hui-juan3, YU Xiao-man7, Lü Xiao-rong2,8

2017, 36(9):  2592-2604. 

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Currently, resource shortage is a global issue. The low resource prices have resulted in extensive consumption and overexploitation in order to meet with the demand of economic development. Firstly, this study applied emergy analysis to calculate the emergy values of natural graphite and spherical graphite. The results show that the emergy values were 1.73E+17 for natural graphite in 2015 and 2.18E+17 sej·t^-1 for spherical graphite in 2010, respectively. According to the corresponding exchange rates between US dollar and RMB, the Emdollars of the natural graphite in 2015 and spherical graphite in 2010 were around 130000 and 160000 ￥·t^-1, respectively. Meanwhile, their corresponding market prices were only 4500 and 14000-18000 ￥·t^-1, respectively. This means that their market prices were far lower than their emergy values. In addition, the emergy values of ecosystem contribution, ecological loss, and damage to human health from spherical graphite production system were also evaluated in this paper. The results show that the emergy value of ecosystem contribution was 1.74E+13 sej·t^-1, while the emergy value of ecosystem service loss was 2.06E+15 sej·t^-1 (much larger than the former one), and the largest damage to human health was dust in this system. This study provides valuable suggestions for preparing appropriate prices of graphite products, normalizing graphite trade and ensuring that graphite industry is moving toward sustainable development.

Effects of habitat fragmentation on biodiversity in China.

WU Qian-qian1, LIANG Zong-suo1, LIU Jia-jia2, YU Ming-jian2, HU Guang3*

2017, 36(9):  2605-2614. 

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Habitat fragmentation has become the primary threat to biodiversity. Due to the rapid economic development in China, a large number of natural intact habitats are suffering from fragmentation, driving a rapid loss of biodiversity in China. This review summarized the studies of effects of habitat fragmentation on biodiversity occurred in China based on different  habitat types， taxa and spatial scales. This review provided basic information for the management and conservation of biodiversity at local and regional scales. We recommended that future studies should focus on multiscale and multidiscipline and longterm fragmentation experiments to reveal the mechanism of habitat fragmentation.

Advances in population epigenetics of plant.

LIU Le-le, DU Ning, PEI Cui-ping, GUO Wei-hua*

2017, 36(9):  2615-2622. 

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Epigenetic variation within species can complement genetic variation as a significant source of phenotypic and functional diversity in natural plant populations. Population epigenetics has been developed for the study of epigenetics in wild species. As a main method in population epigenetics, methylationsensitive amplification polymorphism (MSAFLP or MSAP) analysis has been often used to assess methylcytosine changes though it has many limitations. Reduced representation bisulphite sequencing (RRBS) approach based on nextgeneration sequencing could be a powerful tool in ecological studies. Epigenetics has been applied in the fields of ecology and evolution to explore topics including the relationship between epigenetic variation and genetic variation, epigenetic mechanism of phenotypic plasticity, epigenetic differences in heterogeneous habitats, and epigenetics in polyploidy and speciation events. The important role of epigenetic processes in ecology and evolution has been demonstrated. In this paper we present an overview of the latest research progress of epigenetics in ecology and evolution, and describe the future studies of population epigenetics in plants.

Progress and perspectives of resource use in intercropping system in agro-pastoral ecotone.

ZHANG Yue1,2, DI Wan-tong1,2,5, WANG Jing-jing1,2, DONG Wan-lin1,2,3, YU Yang1,2,4, GOU Fang1,2,4, WANG Qi1, ZHANG Dong-sheng1, GU Sheng-hao1, ZHANG Li-zhen1,2*

2017, 36(9):  2623-2632. 

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Soil erosion and low use efficiency of natural resources in the agro-pastoral ecotone in northern China have become severe problems especially under climate change, which threatens local food security. Concerning the problems existing in rainfed agriculture in the agro-pastoral ecotone in northern China, we discussed how intercropping improves vegetation cover and roughness to reduce soil wind erosion and nutrient leaching; to accelerate the decomposition of organic matter to improve soil fertility; and to increase resource use efficiencies and yields by temporal and spatial distribution of canopy and root structure and the interaction of different crop combinations. The limiting factors of the intercropping on crop productivity and the mechanisms of interspecific interactions were analyzed. Future researches should focus on the effect of climate change on potential yield and soil fertility of intercropping systems. The combination of field experiments and crop models, i.e. processbased crop simulation models and functionalstructural plant models, would be helpful to explore the mechanism of efficient resource use at organ level and to illuminate how intercropping could mitigate climate risk at regional level.

Effects of land use change on soil organic carbon and karst carbon sink in karst area: A review.

LAN Jia-cheng1, XIAO Shi-zhen1,2*

2017, 36(9):  2633-2640. 

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Effects of land use change on terrestrial ecosystem carbon cycle has been becoming a hot topic  research of global carbon cycle and climate change. Land use changes can influence soil organic carbon content, fractions and stability, thus affecting soil CO₂ concentration, and then controlling carbon sink effects of karst geological process. This paper summarizes the effects of land use change on soil organic carbon and karst geological process in karst area, and clarifies the processes and mechanisms of land use change effects on soil organic carbon and its fractions, and the mechanisms of soil CO₂ control, water cycle and inorganic acid disturbance, which influence karst geological process induced by land use change. The aggregate fate and distribution of soil carbon sequestration, mechanisms of physical protection in soil aggregate, and calcium chemical stabilization mechanisms need to be further studied in future. More attention should be paid to how soil CO₂, water cycle and inorganic acid influence karst carbon sink intensity in the process of land use change. The relationships between stable organic matter derived from aquatic photosynthesis by which dissolved inorganic carbon (DIC) was used, and DIC and assimilable organic carbon (AOC) fluxes, and the mechanisms of their response to land use change will become a frontier of karst carbon cycle research. In addition, the influences of rocky desertification control on karst carbon cycle and the technologies for increasing carbon sequestration need to attain more attention.

 

Potential impact of forest fire on soil and water heavy metal concentrations: A review.

ZHU Wen-zhou1, WANG Jun-jian2, ZENG Hui1*

2017, 36(9):  2641-2649. 

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Forest fire is the free spread fire in woodland ecosystems, and it is one kind of common disturbance of ecosystem. Forest fire can potentially release considerable amounts of metals in vegetation and soils through litter layer consumption, vegetation burning, soil organic matter decomposition, and changing the clay minerals, which can potentially impact the heavy metal concentrations in soils and water. Most of previous studies showed that, after the fire, the concentrations of Mn, Cr, Ni, and Pb in soils were increased in short term to various degrees. With increasing time after fire, most of the metal concentrations recovered to the background level eventually; however, it took various time lengths for different metal species. After fire, most of the metals existed in the forms of oxidized and organic bound fractions in soils. As two indicators for soil burn severity, soil pH and electric conductivity correlated with soil metal concentrations in some studies but not for all. Most of the heavy metal concentrations in water increased significantly after fire, indicating that forest fire had potential ecological risks to water body. Future studies should focus on the laboratory and field controlled experiments to reveal the mechanisms of fire effects on heavy metal concentrations in soils and water, providing more data to support forest management and emergency response of disasters.

Sex determination and sex differentiation in amphibians.

TANG Yun1, HU Ying-chao2, ZHENG Le-zhou1, DING Guo-hua1*, LIN Zhi-hua1

2017, 36(9):  2650-2657. 

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Sex development is one of the hot spots in evolutionary biology. It mainly includes sex determination and sex differentiation. There are two mechanisms of sex determination in vertebrates, including genotypic sex determination (GSD) and environmental sex determination (ESD). For amphibians, GSD is a primary mechanism of sex determination, in which the sex is determined by sex chromosomes of bisexual gametes at fertilization, but there is growing evidence showing that the sex is also modified by ambient temperature and sex hormone. The phenomenon of sex reversal generally appears in amphibians, and the physiological and molecular mechanisms have been reported. Here, we summarized the physiological and molecular mechanisms of sex determination and sex differentiation in amphibians, with the focus on the influences of sexrelated genes on sex determination, the effects of temperature and sex hormone on sex differentiation and expression of sexrelated genes. Efforts were made to point out the priority in further studies of sex development in amphibians.

 

Tending effects on secondary forests in subtropical China using the FORET model.

YANG Wen-yu1, KANG Xin1, LUAN Xia-li1, CHEN Bin2, ZHENG A-bao3, HOU Chang-ying3, LIU Mao-song1, XU Chi1*

2017, 36(9):  2658-2664. 

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Improving forest ecosystem services has become one of the most important aims of forest management in the context of current ecological civilization construction. In this paper, four typical subtropical secondary forest communities in Lishui Forest Farm, Jiangsu Province were selected as the study objects. We used the FORET model to simulate forest dynamics of these communities under the natural state and artificial management. By comparing the changes before and after the implementation of management measures in species importance value and total biomass of the stand, we evaluated the effects of different tending management measures. For the Quercus acutissima+Q. variabilis community, there was no obvious difference in changes of forest community composition and structure between under conventional tending measures and in natural development. For the Pinus massoniana+Q. fabri community, Ilex chinensis+P. massoniana community and Q. acutissima+P. massoniana community, which were at relatively early succession stages, comprehensive measures, including released thinning, replanting, and clean cutting, sped up the community succession, and promoted the accumulation of stand biomass. Our results suggested that the forest gap model had a potential application value in the decisionmaking of forest management, and it may be a useful tool for quantitative assessment of forest management effect.

Comprehensive governance model in erosive gully of loess based on terrain analysis.

WANG Xiao-jun, GUO Miao-ling*, WANG Bing

2017, 36(9):  2671-2677. 

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There is serious soil erosion in loess gully. Adopting what kind of comprehensive control model will directly affect the sustainable development of erosive gully of loess. Based on complex open system theory, this paper used the topography analysis method, and focused on two typical erosive gullies of loess in Sanyanjing Watershed, Shouyang County, Shanxi Province, to explore the pattern of regolith stormwater storage. Accordingly, an ecological management mode was put forward. The results showed that the water storage of erosive gully is mainly located in the regolith. The core of the regulation of erosive gully is to combine the habitat and the regolith organically. The method using superposition of high resolution images of large scale topographic map for topography analysis can accurately identify the ecotope composed of retention basinheadland of different scales. Based on the pattern of regolith water storage, rationally allocating plant materials can effectively improve the surface habitat and fundamentally govern the erosive gully of loess. This approach is in line with the natural ecological law, so as to achieve ecological health of erosive gully complex ecosystem in loess.

Swimming performance of Opsariichthys bidens related to fishway design.

JIN Zhi-jun, CHEN Xiao-long, WANG Cong-feng, LI Wei-ming, TU Zhi-ying, KE Sen-fan, GAO Zhu, SHI Xiao-tao*

2017, 36(9):  2678-2684. 

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Opsariichthys bidens, an important economic fish with a small body size, widely exists in the Yangtze River Basin. The swimming endurance, critical swimming speed and sprint swimming speed are important parameters of fish swimming ability, and closely related to the fishway design. Based on the experiments performed in a swimming tunnel, a total of 215 fish (8.78-16.81 cm, TL) were tested, including 128 fish for the test on swimming endurance, 31 fish on critical swimming speed and 56 fish on the sprint swimming speed. Fixed velocity tests revealed that over 84% of the fatigue time was distributed in the two ranges: either <10 min or >200 min. The relationship between fatigue time (E), swimming velocity (V) and total length (TL) could be fitted as lgE=1.603-0.025V+0.146TL (R²=0.562, P<0.001). According to the fitting equation, the relationship between the maximum length of the fishway and the maximum allowable flow can be predicted, and the combined conditions can be tested on the fishway length and maximum water velocity that are suitable for passing Opsariichthys bidens (TL=9.60 cm) at 21.4 °C. Critical swimming speed value of the experimental fish was distributed in 61.07-120.03 cm·s^-1 (the relative critical swimming speed: 6.57-12.65 BL·s^-1), and the range of sprint swimming speed was 65.03-155.07 cm·s^-1 (the relative sprint swimming speed: 5.31-17.95 BL·s^-1). It was concluded that with regard to the sprint swimming speed, 78% of the experimental fish was greater than 1 m·s^-1, and the average sprint swimming speed was about 1.23 times as fast as the average critical swimming speed. The results can provide basis for the hydraulic parameters of the fishway design.