Table of Content

10 January 2017, Volume 36 Issue 1

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Betula platyphylla population structure and its spatial distribution pattern in Taiyue Mountain of Shanxi, China.

TIAN Hui-xia1, LI Jun-min2, BI Run-cheng1, YAN Ming1, Qiao Xiu-hong3*

2017, 36(1):  1-10. 

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Betula platyphylla forest is one of the major vegetation types in Taiyue Mountain of Shanxi, China. Our objective was to explore B. platyphylla population structure and its spatial distribution pattern in this region. Three plots were established according to the diverse age structures of the B. platyphylla population. The B. platyphylla population structure and its spatial distribution at different developmental stages were examined by means of the “spacefortime” substitution approach. The point pattern and fractal analyses including boxcounting dimension analysis, information dimension analysis, and correlation dimension analysis were used in this study. It was found that the diameterclass structure of the B. platyphylla population indicated a typical “spindle” shape, suggesting a declining trend. The young and middle B. platyphylla population was found to show an aggregated distribution pattern, whereas the mature one exhibited a random distribution pattern. It was suggested that along with population development, the spatial distribution of B. platyphylla population varied from aggregation to randomness. The analysis of boxcounting dimension indicated that the degree of the occupied space of B. platyphylla population followed an order of middleaged trees>mature trees>nearmaturity trees. The analysis of information dimension indicated that the changing degree of pattern intensity of B. platyphylla population followed an order of nearmaturity trees>middleaged trees>mature trees. The analysis of correlation dimension showed that the individual spatial correlation of B. platyphylla population followed an order of middleaged trees>mature trees>nearmaturity trees. It was suggested that there were consistent results from population diameterclass structure analysis, point pattern analysis and fractal analysis. All these results revealed the spatial distribution pattern of secondary pioneer community after the destruction of the zonal climax community.

Potentilla froticosa population| physiological and ecological characteristics| vegetation spectral| vegetation index| dynamic change.

QIAO Yu1, ZHAO Chuan-yan2*, RONG Zhan-lei2, XIE Huan-huan1, GAO Chan-chan1, GAO Yun-fei1, WANG Fang-yuan1

2017, 36(1):  11-20. 

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Potentilla froticosa is a most representative alpine deciduous shrub in Qilian Mountains. The growing process of the shrub plays an important role in ecosystem services. In the growing season of 2015, we observed leaf traits of P. froticosa and measured its hyperspectral reflectance by ASD in different phenological phases. The results showed that leaf area, leaf area index (LAI), green leaf area index, chlorophyll content (SPAD values) increased from the beginning of the growing season, reaching their peak in the first half of August, and then declined in the end of the growing season. The change trends of reflection spectrum waveform curve of P. fruticosa shrub in different phenological phases were similar. The correlations between the vegetation indexes (NDVI, EVI, and CI_{red edge}) and LAI, leaf SPAD value were significant (P<0.05) or extremely significant (P<0.001). The relationship between EVI and LAI was the best, and the relationship between NDVI and leaf SPAD value was the most stable. According to the regression analysis, statistic models were built to estimate the LAI and leaf SPAD value considering vegetation indexes in different phenological phases. It is concluded that the LAI and leaf SPAD value can be indicators of plant growth state, and we can monitor the growing process of P. froticosa by the EVI and NDVI derived from remote sensing data at regional scale.

Root characteristics and biomass allocation for Pinus kesiya var. langbianensis plantation.

JIA Cheng-xin-zhuo1,2, LI Shuai-feng1,2, SU Jian-rong1,2*, TONG Qing3

2017, 36(1):  21-28. 

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In this paper, the root characteristics, the biomass allocation patterns of aboveground organs and root in different diameter classes of Pinus kesiya var. langbianensis plantation were studied. Biomass equations for various organs of P. kesiya var. langbianensis plantation were established based on independent variables including DBH and tree height. We aimed at providing a scientific basis for accurate measurement for carbon storage of the P. kesiya var. langbianensis plantation’s arborous layer. The length and specific root length (SRL) of coarse root, large root, medium root and small root increased but the SRL of fine root decreased with the increase of diameter class. The biomass proportion of medium root, small root and fine root decreased first and then increased with the increase of diameter class, while that of coarse root and large root increased first and then decreased. For the same diameter class, SRL of fine root was much higher than that of other roots. Biomass of various organ ranked as stem>branch>root>needle>cone, and the stem biomass accounted for >50% of the total biomass. Each organ biomass increased with the increase of diameter class, and aboveground biomass was significantly positively related with underground biomass. The individual aboveground biomass ranged from 2.23 to 324.95 kg and belowground biomass ranged from 0.52 to 41.80 kg. The biomass of root collar, taproot and lateral root increased with the increase of diameter class. Collar/taproot, collar/totalroot and lateralroot/taproot ratios were significantly positively related with DBH and tree height, and taproot/totalroot ratio had a significant negative correlation with DBH and tree height. AIC_NLR-AIC_LR values were larger than 2, showing that the linear equation was reasonable. The index of R²_adj was 0.661-0.992. The equations including tree height could improve model fitting performance and predicting precision of the biomass of the whole tree and organs except for cone.

Root distribution characteristics of Hedysarum laeve with different aerial seeding years in Mu Us Sandy Land.

ZHANG Lei1,2, WANG Xiao-jiang2, HONG Guang-yu2, WU Yong-zhi2, LI Zhuo-fan2, HAI Long2, WANG Ping-ping2, GAO Xiao-wei2, YANG Jie1

2017, 36(1):  29-34. 

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Taking Hedysarum laeve shrubs with different aerial seeding durations in the Mu Us Sandy Land as the study object, we investigated the root biomass and rhizome numbers of H. laeve at different soil depths using the quadrat mining method to analyze the distribution pattern of H. laeve roots. The results showed that with the increase of aerial seeding duration, the importance value of H. laeve decreased, while the importance value of Artemisia ordosica increased, indicating a trend of H. laeve being replaced by A. ordosica. With the increase of aerial seeding duration, rootshoot ratio of H. laeve decreased, and the value was 3.24, 1.87 and 1.32 for 13, 29 and 37 years aerial seeding plots, respectively. Root biomass and rhizome numbers of H. laeve at different aerial seeding durations significantly decreased with soil depth and aerial seeding duration. Root biomass and rhizome numbers of H. laeve  increased with the decrease of slope position. Most roots of H. laeve distributed in 0-40 cm, and root distribution tended to be more close to the ground surface with the increase of aerial seeding duration and the decrease of slope position.

Capability of capturing different sized particles of common greening tree species in Beijing in autumn.

ZHAO Yun-ge1, LU Xiao-ying2, LU Shao-wei3,4, GU Jian-cai1, CHEN Bo3, LI Shao-ning3,4*

2017, 36(1):  35-42. 

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The particlecapturing capacities of common greening tree species in typical garden areas in Beijing were measured in autumn by aerosol regenerator (QRJZFSQ-I), and the adsorption amount of particulate matter per hectare of woodland was calculated. The results showed that the coniferous species had stronger ability of absorbing particles (PM₁₀, PM_2.5 and PM_1.0) than broadleaf species. The abilities to adsorb different sized particles were not significantly different among coniferous species, but were significantly different among broadleaf trees at Nanhaizi Park, in which Populus spp. (1.256 kg·hm^-2·a^-1) and Salix babylonica (1.153 kg·hm^-2·a^-1) had the strongest adsorption capacity for PM₁₀, and Fraxinus chinensis had the strongest adsorption capacity for PM2.5 (0.367 kg·hm^-2·a^-1) and PM_1.0 (0.107 kg·hm^-2·a^-1). The same species at different sites showed the same adsorption capacity for total suspended particulates (TSP) and PM₁₀, but not for PM_2.5 and PM_1.0. The maximum adsorption (11.043 kg·hm^-2·a^-1) of S. chinensis for PM_2.5 and PM_1.0 was observed at Nanhaizi Park, which was 15 times as much as that at Beijing Botanic Garden. PM₁₀ accounted for a high percentage of the adsorbed particles, and gradually declined along the urbansuburbouter suburban gradient.

Effects of “habitat island” area on plant species diversity and its distribution pattern in Horqin Sand Land.

WU Jing1,2, YU Xin-chun3, LIU Zhi-min1*, HOU Xian-zhang2, QIAN Jian-qiang1,2, XING Bao-zheng2

2017, 36(1):  43-53. 

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Climate change and human disturbance will aggravate habitat fragmentation, resulting in the formation of a series of “habitat islands”. Considering interdune lowlands as the “habitat island”, this study selected 18 interdune lowlands with different sizes in active sand dunes of Horqin Sand Land, to explore the effect of “habitat island” size on plant species distribution pattern and propose different protocols of species diversity conservation. Plant species showed different sensitivities to habitat fragmentation: The type I species mainly distributed in small islands (such as Artemisia wudanica, Phragmites communis and Vicia amoena), the type II species mainly distributed in large islands (such as Lespedeza davurica and Eragrostis pilosai), the type III species mainly distributed in medium size islands (such as Chenopodium aristatum and Sophora flavescens), and type IV species distributed in all types of islands (e.g., salix gordejevii). For given total area of islands, both the total and meadow species richness were in order of the combination of medium size islands > the combination of different sizes of islands > the combination of large islands > the combination of small islands, while both the species richness of psammophyte and steppe species were in order of the combination of different sizes of islands > the combination of medium size islands > the combination of large islands > the combination of small islands. Therefore, exploring the effects of “habitat island” size on plant species diversity and its distribution pattern will provide theoretical basis for plant diversity conservation in semiarid sand dunes.

Predication of potential distribution of Haplocladium microphyllum in China based on MaxEnt model.

MAO Li-hui1,2, LI Yao1,2, LIU Chang1,2, FANG Yan-ming1,2*

2017, 36(1):  54-60. 

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Based on 96 distributional records of Haplocladium microphyllum in China, we predicted the potential distribution of this species in China in different periods, e.g. last glacial maximum (LGM, 21 ka BP), at present and in 2070 by using MaxEnt model, ArcGIS 10.0 and DIVAGIS 7.5 software. The results showed that the accuracy of MaxEnt model was pretty high for modeling present potential distribution regions, and the area under the receiver operator characteristic curve (AUC) reached 0.94. The ideal regions for the present distribution include Sichuan Basin and the middlelower Yangtze Plain. Compared to the present distribution, the distribution of this species was smaller in LGM, and was restricted in the south of 35° N. On the other hand, the distribution region will be extended northward and westward in 2070. Jackknife test showed that the major factors (threshold) contributing to the potential distribution were annual mean temperature (-0.97 to 22.86 ℃), annual precipitation (445-2238 mm) and precipitation of the driest month (1-93 mm).

Host specificity of epiphytic bryophytes in Hangzhou.

GUAN Fei-rong, RU Ya-lu, HU Zhong-jian, CHEN Zun-wei, WU Yu-huan*

2017, 36(1):  61-66. 

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Epiphytic bryophytes, sensitive to the environment change, are a good biological indicator of environmental pollution, climate change and forest health. Studying the diversity and host specificity of epiphytic bryophyte has fundamental significance. Field investigations were carried out on 213 individual trees belonging to 37 species from 21 sites in Hangzhou. There were 48 species of epiphytic bryophytes, and Cinnamomum camphora, Pterocarya stenoptera, and Liquidambar formosana were the most common host trees. DCA ordination showed that the correlation between epiphytic bryophytes and tree species was not significant, and the diversity of epiphytic bryophytes affiliated with each tree was significantly different. Only one moss, Sematophyllum phoeniceum showed significant association with the host, C. camphora. There were certain correlations between Schwetschkea courtoisii and P. stenoptera, and between Entodon challengeri and Diospyros kaki. Other epiphytic bryophytes and tree species are randomly distributed, showing low host specificity.

Nitrogen deficiency and highlight affect photophysiology and lipid accumulation of Palmellococcus miniatus. 

SHI Qi, LIU Teng-zi, HUANG Jian, ZHANG Chen-jun, MEI Hong, WU Hong-yan*

2017, 36(1):  67-71. 

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Microalgae is an ideal biological resource to produce biodiesel. It is important to study the physiological and biochemical characteristics of lipidrich microalgae. In this study, Palmellococcus miniatus, a kind of alkaliresistant green microalgae, was cultured under low (100 μmol photons·m^-2·s^-1) and high (600 μmol photons·m^-2·s^-1) light, and the effects of nitrogen deficiency on photophysiology and lipid accumulation of P. miniatus were investigated. The results showed that nitrogen deficiency decreased the photosystem II maximum photochemical yield (F_v/F_m), inhibited the electron transfer from Q_A^- to Q_B, and lowered the protein content. The inhibition of photosynthesis resulted in the reduction of the growth and biomass. However, nitrogen deficiency induced significant accumulation of lipid. When supplemented with high light, the photosynthesis of P. miniatus was further suppressed and the protein content was decreased to a great extent. In contrast, the lipid content did not show significant change as compared with that under the low light and nitrogendeficient condition. Our results indicated that lipid accumulation was stimulated by nitrogen deficiency, while light intensity showed little effect on it.

Soil nitrogen and Stipa krylovii roots in desert steppe in response to different grazing treatments.

JIN Jing1, WANG Zhan-yi1*, ZHU Guo-dong1, YAO Hong-yun1, NA Na1, HOU Wei-feng1, YU Ze-min2, WANG Cheng-jie1

2017, 36(1):  72-79. 

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An experiment was conducted to investigate the effects of grazing treatments (sheep or cattle grazing, mixed grazing of cattle and sheep, and no grazing) on root architecture of Stipa krylovii in the desert steppe of Inner Mongolia. After grazing for 14 months (two growing seasons), cattle grazing and mixed grazing of cattle and sheep significantly increased nitrogen content of soil at 10-20 cm depth. Cattle grazing improved nitrate content, while the mixed grazing of cattle and sheep mainly improved organic nitrogen content. The aboveground biomass in no grazing area was significantly greater than that in each grazing area, while belowground biomass was insignificantly different among the treatments. After grazing for 14 months, 5 of 6 root architecture parameters of S. krylovii showed no differences among all the treatments. The classification of root diameter showed that root length, volume and surface area in diameter of 4.0-4.5 mm and 2.5-3.5 mm in no grazing area were significantly greater than those of the grazing areas. Overall, 14 months might be too short to change the soil and root architecture of the dominant plant, which deserves further observation.

Effects of nitrogen and phosphorus addition on C∶N∶P stoichiometry in roots and leaves of four dominant plant species in a meadow steppe of Hulunbuir.

GAO Zong-bao1,2, WANG Hong-yi1,3, Lu Xiao-tao1,4, WANG Zheng-wen1*

2017, 36(1):  80-88. 

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There is increasing evidence showing that the nutrient limitation status of plant growth would shift from nitrogen (N) limitation to phosphorus (P) limitation or to N and P colimitation following longterm N deposition. Yet we know little about the ecological consequences of such changes in the relative availability of N and P. In the present study, we examined the chemistry and stoichiometry of C, N, and P in both leaves and roots of four dominant plant species in a meadow steppe of Hulunbuir, including Leymus chinensis, Stipa baicalensis, Bupleurum scorzonerifolium and Thermopsis lanceolata. Our results showed that both N and P addition had no significant impacts on C concentration in roots and leaves of all the species. Phosphorus addition showed no significant impacts on N concentration and C∶N ratios in root and leaves of L. chinensis, S. baicalensis and B. scorzonerifolium. In contrast, P addition significantly increased P concentration in leaves of L. chinensis and S. baicalensis and that in roots of B. scorzonerifolium and S. baicalensis. Nitrogen addition significantly enhanced N concentrations and decreased C∶N ratio in roots and leaves of L. chinensis, S. baicalensis, and B. scorzonerifolium, but had no significant effects on P concentration and C∶P ratio in roots and leaves of L. chinensis and B. scorzonerifolium. Moreover, N addition significantly increased the P concentration and decreased the C∶P ratio in roots and leaves of S. baicalensis. We found positive effects of N addition on  N∶P ratio of plant tissue in three out of the four species. All the examined nutrient characters in T. lanceolata showed no significant responses to both N and P addition. We found no significant interactive effects of N and P additions on the chemistry and stoichiometry of plant tissue. Results from this study highlight the role of species identity in driving the responses of plant stoichiometry to the alteration of nutrient availability, which would help predict the changes of plant community composition in the scenarios of nutrient enrichment.

Himalayan Cuckoo fed on eggs of Bianchi’s Warbler.

SU Tong-ping1,2, SHAO Ling2, HUO Juan2, YANG Can-chao2, LIANG Wei2*

2017, 36(1):  89-93. 

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Some avian parasites (i.e., cuckoos) usually remove or eat one or two host eggs before laying their own eggs on host nest. This behavior indicates that parasitic cuckoos could also be nest predators. Two hypotheses have been proposed to explain the cuckoo predation behavior: (1) cuckoos may depredate host nests that are unsuitable for parasitism and force the host to renest, then cuckoo would get more chance for parasitism (nest farming); (2) cuckoo may depredate host nests as a retaliatory behavior if the host rejected cuckoo’s eggs. In Kuankuoshui National Nature Reserve, Guizhou, southwest China, we found one case of the Himalayan Cuckoo (Cuculus saturatus) fed on eggs of the Bianchi’s Warbler (Seicercus latouchei) by using a video record in June 2015. To our knowledge, this is the first report on predation of the Himalayan Cuckoo on its warbler host. This study shows that the Himalayan Cuckoo is not only a brood parasite but also a nest predator. The motivation of cuckoo predation on warbler nest of this record seemed to meet with the first hypothesis, namely nest farming.

Bird community structure and seasonal variation in Wulanchabu, Inner Mongolia, China.

LIANG Chen-xia1, LI Bo1, ZHANG Yu-wei1, YANG Fan1, YANG Gui-sheng1*, WANG Zhi-heng2, PAN Bin1

2017, 36(1):  94-103. 

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To understand the seasonal variation of bird community structure and its influence factors, we sampled birds in six types of habitats in Wulanchabu, Inner Mongolia, China, from October 2012 to December 2013, using the methods of fixedradius points and line transects. A total of 153 bird species belonging to 45 families and 17 orders were recorded. Among them, 76 species were summer visitors, 38 passage migrants, 34 residents and 5 species winter visitors. The summer visitors were the richest group in spring, summer and autumn, and resident birds were only dominant in winter. The proportion of nonPasseriformes birds was apparently higher than that of Passeriformes. Both Shannon index and Pielou index of bird communities were the highest in spring and the lowest in winter. Cluster analysis indicated bird community was most similar in spring and autumn. Bird community structure in different habitat types also showed seasonal changes, with wetland bird diversity being the highest in spring, summer and autumn, while bird communities of the farmland and residential area were similar. Habitat type, food resources and bird migration were important factors driving seasonal variation of bird community structure in this region.

Economic threshold of the second-generation Asian corn borer to corns in Liaoning Province.

LI Shuai-qiang, ZHANG Tong-shu, LIU Ning, LIU Chao, HAN Yong-xu, DONG Hui*, CONG Bin1*

2017, 36(1):  104-109. 

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To determine the influence of second-generation Asian corn borer (Ostrinia furnacalis) (Guenée) on corn yield, we simulated the damage caused by Asian corn borer under natural conditions, to study the economic threshold of the secondgeneration Asian corn borer in Liao-ning. Field tests were conducted to infest the spring corn LD565 with a series of egg mass numbers (0, 20, 50, 100 and 200 eggmasses per 100 plants). Correlation analysis revealed that egg mass number per 100 plants showed a significant positive correlation with stalk hole number per 100 plants (P<0.01), with a regression equation y=3.1999x+24.8416 (R²=0.953, P<0.01); stalk hole numbers per 100 plants showed a significant positive correlation with yield loss rate (P<0.01), with a regression equation y=0.0234x-1.6167 (R²=0.988, P<0.01). The correlation between the number of eggmasses per 100 plants and corn yield loss rate met the equation z=0.0749x-1.0354, meaning that stalk holes would increase by 3.2 and maize yield loss would increase by 7.49% with per one increase in egg mass number. Tunnel length showed a negative correlation with ear length, ear diameter and yield weight per plant (P<0.01), while a positive correlation with yield loss rate (P<0.01). Maize yield loss would increase by 4.38% with per 10 cm increase in tunnel length. In conclusion, the economic threshold of applying richogramma dendrolimi Matsumura to control Asian corn borer would be 17.39 eggmasses per 100 plants in the field with a grain yield of 8411 kg·hm^-2.

The response of Collembola to plant leaf returning into phaeozem cropland of Northeast China.

LI Jiu-jia1,2, CHANG Liang2, ZHU Xin-yu2,3, LIU Jie1,2, SUN Xin2, WU Dong-hui1,2*

2017, 36(1):  110-117. 

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Weed management is an important practice in agricultural activities and is known to influence aboveground biodiversity in cropland. To understand the influence of weeds on soil biodiversity, we conducted a litterbag experiment to investigate the effects of weed leaves (Amaranthus retroflexus and Echinochloa hispidula) and maize leaves (fresh and mature) on soil Collembola in Jilin Province, China. A total of 6269 collembolans were collected and classified into 11 species representing 9 genera from 5 families. The dominant taxa were Thalassaphorura encarpata, Heteroisotoma sp. 1, and Folsomia sp. 1. Leaf addition, especially fresh corn leaves, significantly increased soil collembolan abundance and changed the community composition. More-over, the decomposition rate of A. retroflexus leaves was significantly higher than the decomposition rates of the other leaves. The results indicated that the substrate quality of leaves plays an important role in collembolan community composition and thus in the process of decomposition in cropland. The decomposition rate of leaf had no significant correlation with the number of collembolans, which may be related in the diets of collembolans.

 

Effects of different land use types on spatial-temporal distribution of earthworm density and biomass.

WANG Shao-jun1，2*, WANG Hong1, LI Ji-hang1

2017, 36(1):  118-123. 

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To understand the effect of land use change on spatial-temporal distribution of earthworms, we surveyed the vertical distribution and seasonal dynamics of earthworm density and biomass across the three land use types (i.e., urban forest, open forest and seedling nursery), and analyzed the effect of soil physicochemical properties on earthworm density and biomass induced by land use change. We found that: （1) The density of earthworms was ranked as urban forest (59 ind·m^-2) > seedling nursery (24.7 ind·m^-2) > open forest (ind·m^-2), showing a significant influence of land use change on earthworm density; however, the effect of land use change on earthworm biomass was not significant; （2) The density and biomass of earthworms were ranked in the order of urban forest> open forest> seedling nursery, and a significant effect of land use change on the vertical distribution of earthworm density and biomass was observed. The density and biomass of earthworms were greater in wet season than in dry season, which was closely related to soil moisture; （3) The density and biomass of earthworms were in the order of 0-5, 5-10, and 10-15 cm soil layer, which was closely related with the vertical change of soil moisture, soil organic matter and total nitrogen; （4) Earthworm density was significantly positively correlated with soil moisture, pH and soil organic matter, while earthworm biomass had significant positive correlation with soil moisture and soil organic matter. Therefore, the change of land use type played a critical controlling role in the spatialtemporal dynamics of earthworm density and biomass mainly through its effect on the soil environment, and the greatest abundance of earthworm was found in the urban forest.

Variations of growth and physiological indicators of Eisenia foetida in soils across a chronosequence of Eucalyptus grandis plantations.

YU Jun-li, ZHANG Jian, TANG Zhi-qun, WANG Chun-zi, QIAN Li-zhi, ZHANG Dan-ju*

2017, 36(1):  124-131. 

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Allelopathy is regarded as one of the main mechanisms for the ecological problems of Eucalyptus plantations. In the present study, a chronosequence of Eucalyptus grandis plantations (2, 4, 6, 8, 10 years old) in Danling County, Sichuan Province was selected to evaluate the allelopathic effects of soils on earthworm. The growth indicators (growth rate, survival rate) and physiological indicators (protein, superoxide dismutase (SOD), acetylcholinesterase (AChE), glutathione Stransferase (GST), malondialdehyde (MDA)) of Eisenia foetida were measured in the soils from various aged E. grandis plantations. The survival rate of E. fetida did not change significantly with the plantation age and exposure time. The weight inhibition of E. foetida increased ignificantly with exposure time, whereas the weight inhibition rate increased at 7-14th day and then decreased with exposure time. At the exposure time of 7^th and 14^th day, the weight inhibition rate increased firstly (2-6 years old) and then decreased (6-10 years old); however, the weight inhibition rate had no significant changes with plantation age at the 21^th and 28^th days of exposure. E. foetida represented no significant avoidance responses with the increasing E. grandis plantation age. After the exposure time of 28 days, there were no significant effects on the protein content and AChE activity under the treatments of soils from 2-8 years old E. grandis plantations and then increased with plantation age. SOD activity of E. foetida decreased significantly in the soils of 4 and 10 years old stands, but was stable in other treatments. Overall, GST activity increased significantly with plantation age, especially for 6-8 years old stands, and was stable for other aged plantations. MDA content was stable in the soil of 2-4 years old stands, increased significantly in the soil of 6 years old stand and then was stable with increasing E. grandis plantation age.

Butterfly species diversity in Gutian Provincial Nature Reserve, Guangdong.

WENG Jin-qiu1, LV Wen-long1, HU Shi-jia2, ZHENG Ji-huan2, LI Zhi-gang2*

2017, 36(1):  132-136. 

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A survey with line transect method was conducted on the butterfly species diversity in Gutian Provincial Nature Reserve, Huizhou in 2014-2015. Fiftyfour species of butterfly belonging to 39 genera and 8 families were identified. The dominant species were Eurema hecabe (Linnaeus), Parantica aglea (Stoll), Neptis hylas (Linnaeus), Euploea mulciber (Cramer) and Danaus genutia (Cramer). Nymphalidae had the highest Margalef richness index, followed by Papilionidae and Satyridae, and Danaidae and Riodinidae the lowest. Shannon diversity index decreased in order of Nymphalidae, Papilionidae, Satyridae, Hesperiidae, Lycaenidae, Pieridae, Danaidae and Riodinidae. Danaidae had the highest Pielou evenness index, followed by Riodinidae and Satyridae. Riodinidae had the highest Simpson dominance index, followed by Pieridae and Danaidae.

Reproductive biology of exotic fish Clarias gariepinus (Burchell, 1822) in south China.

ZHU Yun-jie1,2, GU Dang-en1, WEI Hui1, MU Xi-dong1, LUO Du1, XU Meng1, LUO Jian-ren1, HU Yin-chang1*

2017, 36(1):  137-143. 

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A total of 255 fish specimens of invasive species Clarias gariepinus were collected from the main rivers of south China, to analyze its reproductive characteristics. The results showed that females spawned from May to August, and the spawning peak occurred in June and July. The distribution of egg-diameter presented a multipeak pattern. Fat coefficient and fullness coefficient had obvious seasonal changes, and had an opposite trend with gonadosomatic index. The absolute fecundity ranged from 2850 to 605720 eggs with an average of 234232 eggs, and had a positive correlation relationship with body length, weight and age. The relative fecundity varied from 20 to 445 eggs·g^-1 with an average of 165 eggs·g^-1, and initially increased with body length, weight and age, and then became stable. Absolute fecundity and relative fecundity of C. garipinus were greater than those of other Siluridae fishes. Sex ratio of C. garipinus was 1∶1.12 in breeding season, and had no obvious difference with 1∶1. The shortest mature females (body length: 174 mm; weight: 119.5 g; gonadosomatic index: 8.50%) and males (length: 250 mm; weight: 116.2 g; gonadosomatic index: 0.45%) were 1 year old with Ⅳ period gonads. The age composition of breeding population mainly consisted of ages 1 and 2, which accounted for  42.28% (age 1) and 51.68%(age 2) of the total specimens. The results suggested that reproduction characteristics (i.e. multiple batch spawning, highly relative fecundity, small eggs, mature at early age) of C. gariepinus might be conducive to its invasion in south China. It is necessary to strengthen monitoring for the wild populations of C. gariepinus, and take further measures to prevent and control this fish species in the invaded regions.

Influence of CO₂induced seawater acidification on the antioxidant parameters, development and reproduction in Tigriopus japonicus.

CHEN Yao*, DONG Wei-feng, DAI Hong, YANG Bi-cheng, CHEN Zhang-fei

2017, 36(1):  144-149. 

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This study, via biochemical and ecological methods, investigated the influence of CO₂induced acidification on the antioxidant parameters (i.e., superoxide dismutase, SOD; catalase, CAT; glutathione Stransferase, GST; and lipid peroxidation, LPO), development time and fecundity in marine copepod Tigriopus japonicus. The results showed that acidification significantly induced the antioxidant enzyme (SOD and CAT) activities, and increased LPO level in the copepod, while the GST activity was not affected, indicating that T. japonicus might increase the activities of SOD and CAT to fight against oxidative stress caused by acidification. In addition, development time for nauplius phase and development time to maturation in T. japonicus were strikingly shortened by acidification, which significantly inhibited the copepod’s fecundity. Thus, acidification could affect the population level of this copepod, i.e., population replenishment and dynamics. In summary, this study demonstrated that ocean acidification could cause oxidative stress on copepod T. japonicus, hence inducing oxidative damage to biological macromolecules (such as proteins, nucleic acids, etc.), and ultimately affecting its individual level and population dynamics (e.g., shortened development time and suppressed fecundity).

Effects of straw returning on nutrient content and ecological stoichiometric ratio of soil waterstable aggregates in paddy field.

AN Wan-li1, XIE Hai-yun1, WANG Wei-qi1,2, ZENG Cong-sheng1,2*

2017, 36(1):  150-156. 

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The effects of straw returning on total carbon (TC), total nitrogen (TN), total phosphorus (TP) contents and their ecological stoichiometric ratios of soil waterstable aggregates in the early and late paddy field of Fuzhou plain were analyzed. The results showed that the TC, TN, TP contents and the TC∶TN ratio of aggregates were increased to different degrees in the early paddy, specially for the TC, TP contents and the TC∶TN ratio in 1-2 mm soil waterstable aggregates, which were increased by 42.3%, 22.2% and 29.1% (P<0.05), respectively, while the TC∶TP ratio was decreased to some extent and the TN∶TP ratio was not significantly changed after straw returning. In late rice paddy, the contents of TC and TP in 1-2 mm waterstable aggregates were significantly decreased (P<0.05). The TC∶TN ratio in aggregates was not significantly changed. The TC∶TP and TN∶TP ratios were increased in 1-2 mm soil waterstable aggregates, but decreased in the other sized aggregates in late paddy. In terms of the aggregate fractions, the soil TC, TN, and TP were mainly distributed in the waterstable macroaggregates (0.25-2 mm size), which were decreased as the decreasing size of aggregates in early and late paddy. Straw returning enhanced the soil nutrient contribution rates of waterstable macroaggregates but reduced the soil nutrient contribution rates of waterstable microaggregates (<0.25 mm size) in the late rice paddy. In general, the waterstable aggregates of 1-2 mm size were sensitive to straw returning in the early and late paddy. Straw returning had effects on the nutrient content of soil waterstable aggregates, while it had no significant effect on the nutrient stoichiometric ratio in the paddy field of Fuzhou.

Soil water distribution before and after a rainfall event at sand dune-interdunes in Horqin Sandy Land, Northern China.

ZHOU Xue-ya1,2, YANG Ting-ting1,2, WANG An-zhi1, GUAN De-xin1*, YUAN Feng-hui1, WU Jia-bing1, JIN Chang-jie1

2017, 36(1):  157-163. 

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In this paper, a typical landscape unit, dune-interdune in Horqin Sandy Land was selected as study object, and the characteristics of soil moisture distribution and rainfall recharge along terrain before and after a moderate rainfall event (22.6 mm) were analyzed. The results showed that, in the horizontal direction, there were  significant differences among the mean soil moisture content (SMC) of 0-90 cm depth at different locations. Before rainfall, the order of SMC at different locations was interdune (10.30%), downslope (1.18%), dune top (0.98%) and upslope (0.75%); after rainfall, the rate of SMC increment was 2.33% for dune top, 3.50% for upslope, 1.77% for downslope and 0.34% for interdune. In the vertical direction, soil moisture distribution with depth before and after rainfall was related with locations. Before rainfall, surface SMC was quite low and mean SMC was slightly higher at 40-100 cm depth of dune top, and at 20-50 cm and 120-200 cm depth of upslope. At downslope and interdune, SMC increased with depth up to saturated values. After rainfall, soil water storage increased at 0-110 cm, 0-110 cm, 0-50 cm and 0-90 cm depth at dune top, upslope, downslope and interdune, which were 12.4%, 13.3%, 9.7% and 14.6% of rainfall, respectively. At 0-10 cm layer, soil water storage increment at interdune was significantly higher than that of dune top and upslope, and there were no significant differences at other layers among different locations (P<0.05). During the period with no rain for long time, soil water at dune top and upslope was in deficit, and it is necessary to take measures to maintain a dynamic balance in soil water, which is good for vegetation restoration and desert reversal.

Dominant ecosystem services of Shuangtai estuary wetland based on different beneficiaries.

SUN Bao-di1,2, CUI Li-juan1,2*, LI Wei1,2, KANG Xiao-ming1,2

2017, 36(1):  164-171. 

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Due to the diversity of wetland ecosystem services, the imbalance of their spatial distribution and the selectivity of human use, the relations between wetland ecosystem services will have tradeoffs and mutual gain variations under the effects of anthropogenic and natural factors. Understanding the degree of concerns on the wetland ecosystem services from different beneficiaries is of great importance to formulate regional development and wetland protection policies and measures. In our study, we selected the Shuangtai Estuary National Reserve in Liaoning Province as the study region, and used the analytic hierarchy process (AHP) to pairwise compare different wetland ecosystem services, including substance production, flood control, carbon sequestration, climate regulation, gas regulation, creating land with silt, eliminating waves for revetment and leisure tourism at four levels of beneficiaries from local, provincial, national and global administrative areas. We also used the expert scoring method to grade those wetland ecosystem services from the four levels of beneficiaries. The results showed that the local beneficiaries mainly focused on substance production and eliminating waves for revetment, with weights of 0.2234 and 0.2154; provincial beneficiaries mainly focused on leisure tourism and climate regulation, with weights of 0.2740 and 0.2230; national beneficiaries mainly focused on climate regulation and the gas regulation, with weights of 0.2155 and 0.2150; global beneficiaries mainly focused on carbon sequestration and gas regulation, with weights of 0.2939 and 0.2161. Moreover, based on the different social attribute characteristics of different interviewees, such as age, income, education background and profession, our results showed that different beneficiaries with different social attributes focused on different wetland ecosystem services. These results can provide theoretical supports for the choice of the values of different ecosystem services and also for the tradeoffs among different beneficiaries in the future.

Uncertainty analysis of potential evapotranspiration and its influencing factors in Heihe River.

WANG Jing-hai1, QI Guang-ping1*, KANG Yan-xia1,2, ZHU Xuan-hao1, MA Yan-lin1, SHI Xiao-wei1

2017, 36(1):  172-180. 

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Using the daily data during 1951-2014 from 17 meteorological stations in Heihe River watershed and the surrounding areas, uncertainty analysis of potential evapotranspiration (ET₀) and its influencing factors were studied based on cloud model, which is a mathematical representation of a qualitative concept and integrates the fuzziness and randomness of a qualitative concept in a unified way. Meanwhile, the causes of ET₀ change were manifested by path analysis. The results showed that annual variation in ET₀ had a fluctuating increase tendency. The homogeneity and stability of ET₀ were worse in space than in time, indicating that the temporal distribution of ET₀ was more uniform and stable. Further analysis found that entropy (E_n) and hyper entropy (H_e) of meteorological elements had smaller extents of variation, indicating that the spatial distributions of meteorological elements were uniform and stable. However, the spatial distribution of E_n and H_e differed greatly with the spatial distribution of expected value (E_x). Spatially, the ET₀ increased from the south of Heihe River to the north; this pattern was similar to mean temperature, sunshine hours and wind speed, and was opposite to relative humidity. Relative humidity was the main influencing factor of ET₀, followed by wind speed and temperature. The wind speed and relative humidity had the largest direct effect on the ET₀, while the relative humidity and mean temperature had the largest indirect effect on the ET₀. The negative effect of air temperature and relative humidity on ET₀ by wind speed was obvious.

Remote sensing estimation and the reasons for temporal-spatial differences of vegetation net primary productivity in  arid region of Northwest China.

JIAO Wei1,2, CHEN Ya-ning1*, LI Zhi1

2017, 36(1):  181-189. 

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Vegetation net primary productivity (NPP) is an important parameter to evaluate a terrestrial ecosystem. Based on MODIS NDVI data from 2000-2014, we improved CASA model with land cover type, classification resolution, radiation data selection and formula selection, and calibrated the model according to the local natural environment in Northwest China. Then we estimated NPP and analyzed its temporalspatial distribution pattern. The results showed that the improved model gave a good vegetation NPP estimation in the arid and semiarid areas and reflected the vegetation growth and distribution in the study area; the mean annual vegetation NPP was 191.63 g C·m^-2·a^-1. There was an obvious regional difference in NPP distribution in the arid area in Northwest China, basically being high in the northwest and southeast and low in the center. There was an increasing trend in annual NPP with an annual rate of 2.98 g C·m^-2·a^-1, which differed with vegetation types, being the largest in cropland, followed by shrub, and least in woodland. Vegetation NPP had a significant correlation with precipitation (r=0.538, P<0.05) and no significant correlation with temperature (r=0.394), indicating that vegetation NPP was more highly correlated with precipitation than with temperature; the correlation coefficient differed with vegetation types.

Analysis of temporal and spatial characteristics of growing season drought in Liaoning Province based on standardized precipitation-evapotranspiration index.

ZHANG Yun-fu1*, FANG Yi-he2, GONG Qiang3

2017, 36(1):  190-197. 

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Based on the monthly precipitation and temperature data from 50 meteorological stations during 1961-2015, the temporal and spatial characteristics of drought in growing season in Liaoning Province were analyzed using the standardized precipitation-evapotranspiration index (SPEI), linear trend analysis, MannKendall abrupt test and empirical orthogonal function (EOF). The results showed that the SPEI significantly decreased with a rate of 0.1310 a^-1 and the overall trend of drought increased from 1961 to 2015 in Liaoning Province. The drought intensity varied with time, i.e., it was gradually weakened in the 1960s and 1970s, gradually strengthened at the beginning of 1980s, then continuously decreased from the early 1980s to midlate 1990s and finally strengthened continuously from the late 1990s to 2015. In 1996, the SPEI for the whole province abruptly decreased with a sudden enhancement in the drought intensity. Especially in 2000, the largest range of drought in recent 55 years occurred at 47 meteorological stations, accounting for 94% of the total area. The drought rates were 92% and 88% in 1999 and 2014, respectively. There were three major modes for the spatial distribution of SPEI, i.e., the regional consistent type, the reverse type between southeast and northwest and the reverse type between central and other regions. The regional consistent type with high values included coastal Huludao, Jinzhou, Shenyang and Anshan, which indicated that these areas were most sensitive to drought. There was a significant decreasing tendency in the time coefficient of the first mode. In the reverse type between southeast and northwest, the zero value line of space coefficient located at the central Liaoning exhibiting northeastsouthwest. The space coefficient of the west and the north of Liaoning located to the west of zero value line was negative, but the space coefficient of the regions in the east of zero value line was positive. There was no clear tendency in the time coefficient of the second mode. In the reverse type between the central, Bohai coast and other-regions, the space coefficient was positive in southeast and west regions, but negative in other-regions, showing no significant tendency in the time coefficient.

The temporal and spatial clustering characteristics of forest fires in the Great Xing’an Mountains.

LI Shun1,2, WU Zhi-wei1*, LIANG Yu1, HE Hong-shi3,4

2017, 36(1):  198-204. 

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Forest fire is one of the main disturbances in the Great Xing’an Mountains. Revealing temporal and spatial distribution characteristics of fire occurrence in this region was important for local fire management and fire prediction under climate change scenarios. Generally, distribution patterns of fire occurrence may vary at temporal and spatial scales. In this study, we used historical fire ignitions occurred between 1967 and 2006 to derive fire clustering characteristics at various spatial and temporal scales in the Great Xing’an Mountains. We employed the coefficient of variation and Allen Factor to derive the temporal clustering scope of fire occurrence, and used the Ripley’s K function and Kernel density methods to estimate the spatial clustering characteristics of fire occurrence. The results showed that at a fine temporal scale, fire distribution was in a tendency of stochastic process. The timeclustering phenomenon was clearly visible as the observation time increased. Spatially, the fires showed aggregated distribution characteristics within certain distances. Exceeding these distances, fires showed stochastic Poisson distribution characteristics. The forest fires were located in certain areas, where there was a significant high occurrence density across the landscape. These results indicated temporal and spatial distribution patterns of forest fires in the Great Xing’an Mountains, yet lacked an indepth research about the impact mechanism of the fire patterns, which remains to be solved.

Landscape ecological effect of urban expansion in the central area of Chongqing City based on gradient analysis.

CUI Wang-ping1,2, LI Yang-bing1,2*, LI Rui-kang1,2, ZHOU Ya-lin1,2, WEN Wen1,2

2017, 36(1):  205-215. 

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To study the change of landscape pattern and its landscape ecological effect in rapid urbanization area is helpful to strengthen the urban ecological environment planning and land management. In this paper, taking the central area of Chongqing City as the research object, with the help of Fragstats 4.2 and ArcGIS 9.3 software, in combination with methods of landscape expansion index, landscape human active interference index and landscape pattern analysis, a comprehensive analysis on the ecological effects of landscape change caused by the urban expansion from three aspects, including the urban expansion model, human disturbance intensity, and landscape pattern gradient in the study area during the period from 1995 to 2014 was conducted. The edge expansion mode was dominant but showed a weakening trend over time, the outlying expansion mode continued to strengthen, while the infilling expansion mode was always the lowest after 2001, due to the influence of topography and traffic in the study area. During the period from 1995 to 2014, the low intensity, and lowmedium intensity landscape area, mainly including forest, grassland, water, was stable and increased slightly, while the high intensity area, including urbanrural residential land and industrial land, showed a spread trend toward the medium and mediumhigh intensity area, and the dry land and paddy field had seriously disappeared. The values of patch density, mean Euclidean nearest neighbor distance and Shannon’s diversity index were higher with the increase of the distance from the center of city along the southnorth and the eastwest transects, but these values near the center area of city showed a decrease trend over time. The spatialtemporal change of contagion index was opposite to the abovementioned. Therefore, the gradient change of landscape pattern had a significant spacetime difference in the local area between the northsouth and the eastwest transects, which would have a profound impact on the ecological effects caused by the change of landscape composition in the process of urbanization.

Influence of different water regimes of tributaries in Three Gorges Reservoir on airwater interface CO₂ fluxes.

CHENG Yao1,2，3*, WANG Yu-chun2，3, HU Ming-ming2，3

2017, 36(1):  216-223. 

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Zhuyi River, Caotang River, two tributaries of Three Gorges Reservoir (TGR), and its adjacent mainstream were selected as survey area. In the spring algal bloom period, the airwater interface greenhouse gas fluxes in relation to environmental factors were observed in March, 2015. The results showed that during this period, the mainstream of TGR was a source of CO₂ and its flux was 85.01 mmol·m^-2·d^-1. Zhuyi River, slightly influenced by the mainstream, was a sink of CO₂, and its flux ranged from  -73.26 to -30.38 mmol·m^-2·d^-1. However, Caotang River, intensely influenced by the mainstream, was a weak source of CO₂, and its flux ranged from 81.43 to 136.72 mmol·m^-2·d^-1. Correlation analysis showed that the CO₂ fluxes of different areas in TGR had a significant correlation with primary productivity of plankton. Influenced by the TGR operation, the difference of water regimes in different water areas in mainstream and tributaries resulted in spatial difference of biomass of plankton and intensity of carbon conversion and utilization, which would be the main factor for the high heterogeneity in the source or sink for airwater interfaces CO₂ in TGR.

Relationships between biological nitrogen fixation and available nitrogen at scales from molecular to community level.

CHE Rong-xiao1,2, DENG Yong-cui3, WU Yi-bo4, ZHANG Jing1, WANG Fang1, TANG Li1,2, LI Lin-feng1, MA Shuang1, LIU Han-ke1, ZHAO Xing1, WANG Yan-fen1, HAO Yan-bin1, CUI Xiao-yong1*

2017, 36(1):  224-232. 

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As the anthropogenic nitrogen input to the global ecosystem is experiencing an unprecedented rise, quantifying the relationships between biological nitrogen fixation (BNF) and available nitrogen is not only essential to estimating ecosystem nitrogen budgets, but also crucial to optimizing fertilization strategies. In this paper, research results on the effects of available nitrogen on BNF at scales from molecular, individual, to community level, were synthesized and compared. We found that the studies at molecular and individual scales are more systematic than communityscale studies, but are severely limited by the cultivability of diazotrophs; while the studies at the community scale employed the cultureindependent methods, and thus are more efficient. However, at the community scale, very few studies focused on the expression of nitrogenase genes, and the study system is still far from perfect. Therefore, future studies should pay more attention to the regulation of available nitrogen on the nitrogenase gene expression at community scale, with special emphasis on improving the communityscale research system of BNF.

Research advances in water competition and complementary interaction of intercropping agroecosystems.

CHAI Qiang*, YIN Wen

2017, 36(1):  233-239. 

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The mechanisms of interspecific competition and complementarity and the characteristics of water utilization in intercropping system are reviewed in this paper. Meanwhile, key research fields related to intercropping in the future are prospected. Intercropping system can increase water use efficiency (WUE) of crops, and is in favor of providing an optimum soil moisture environment for crop development. Competition and complementarity are two aspects of the same interspecific relationship; quantifying competition and complementary effect of intercrops on soil resources is an important topic in intercropping system. The main influence factors for interspecific competition and complementarity in intercropping system include crop species, planting density, spatial arrangement, and environmental factors. Interspecific competition and complementarity are leading factors influencing water utilization of intercrops and studies on synergistic effects of competition and complementarity in intercropping systems are limited. Prospective future research fields are identified as follows: (1) To determine the dynamics of dry matter accumulation, allocation and irrigation water productivity, to study compensation effects on water use in latematuring crops after the earlymaturing crops were harvested in intercropping systems, and to clarify the correlation between WUE of crops and interspecific interaction. (2) To investigate spatiotemporal dynamics of soil water potential and available soil water, and to analyze the relationships among soil water movements within interspecific competition and complementarity, in order to provide theoretical basis for optimizing interspecific competition and complementarity under irrigation regulations. (3) To evaluate the effects of intercropping on crop moisture physiological and ecological characters so as to reveal the complementary mechanism of interspecific interaction with respect to hydrophysioecological viability. (4) To explore the correlations between rootshoot equilibrium and spatiotemporal distribution of root, as well as water use characteristics and interspecific competition and complementarity, to elucidate how the rootshoot equilibrium works on improving WUE via the synergistic effects of inter specific competition and complementarity. By integrating the main results at different scales, theoretical basis for enhancing WUE of intercropping through regulating interspecific interactions could be established, which provides support for development and extension of intercropping systems in waterdeficient areas.

The influence of dam on downstream landscape pattern and ecosystem services.

FAN Yu-long1,2, HU Nan2, DING Sheng-yan1*

2017, 36(1):  240-247. 

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Dam is an effective utilization and regulation method for water resource, which has made an important contribution to social and economic development. Dam changed river natural attributes, being the important driving force for the downstream landscape and its ecological system services. Dam changed the spatial and temporal distribution of regional water resources, which generated the corresponding water effects at different scales and different levels: (1) Dam caused physical, chemical, and biological changes of the river, from downstream to estuary. These changes mainly took place in river channel, hydrological and species flow, etc. (2) The changes of the surface water and groundwater affected the riparian zone, irrigated area, flood plain and horizontal region. Reduced water supply ability had great influence on the underground aquifer and the wetland. The interaction between the main stream and tributaries and lakes was blocked, influencing the transmission and exchange of water. (3) The change of water environment influenced the degree and direction of social and economic development, and the downstream land use and land cover changed correspondingly. Ecosystem services had been realized by cooperation of geographic process, biological process and social economic development. Dam changed the water, energy and material cycling process, which would have longterm and farreaching influence on the maintenance of regional ecosystem services. Dam strongly changed regional ecosystem services network’s stability and development through affecting the downstream primary and secondary effects.

Structure and distribution characteristics of sex pheromone components in Crambidae insects.

WANG Pan1, WANG Hai-yang2, SHAN Jun-qi1,2, WANG Xiao-ping2, LEI Chao-liang2, SI Sheng-yun1*

2017, 36(1):  248-257. 

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The species of Crambidae distribute worldwide, and many of them are important agricultural and/or forest pests. Synthetic sex pheromones have been used as a specific and environmentallyfriendly tool of Integrated Pest Management (IPM). In this paper, we did statistical analysis and categorization on the Crambidae species, whose sex pheromone components have been identified, and their sex pheromone components. We also compared the chemical structure of the sex pheromone components and their distribution characteristics among different subfamilies, genera and species. This review can provide evidence for further identification of sex pheromone components of other Crambidae species, and also can provide basic data to further explore the evolution of moth insect sex pheromones.

A nonthroughpith method for tree stem analysis.

ZHANG Ning, LIU Qi-jing*, MENG Sheng-wang, ZHOU Hua, LIU Wen-hui

2017, 36(1):  258-266. 

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Stem analysis is the most fundamental technique in forest mensuration. The traditional method for measuring diameters of tree rings is to average two geomagnetic directions (southnorth and eastwest) passing through the pith, which are perpendicular to each other. Since disks are usually eccentric, biomass or section area estimated by diameters passing through the pith can be significantly underestimated in general, which has been ignored in the past. This oldstyle method has never been challenged in dealing with accuracy. A new method, tested by digital photo technology, for getting individual ring diameters more close to the real diameters, was proposed in this paper. The line representing diameter of a ring was not necessarily set through the pith, rather on a subtense close to the real diameter. The ring diameters of the disks were measured by using different methods for accuracy comparison. It is proved that this method is more accurate than the traditional one tested by circularity index and closeness index. The method is easier for operation compared with the traditional one, which is expected to reduce the uncertainty in the measurement of tree growth as well as forest productivity.

Evaluating the applicability of ecological model for simulating evapotranspiration and soil water content in winter wheat farmland. 

ZHANG Xue-song1*, LIU Ya-ge2, HU Zheng-hua1,3, LIU Yi-bo1, ZHANG Fu-cun1, HAN Xiao-mei1

2017, 36(1):  267-276. 

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To assess the applicability of ecological model for simulating evapotranspiration and soil water content in farmland, BEPS (Boreal Ecosystem Productivity Simulator), a processbased ecological model, was employed to simulate daily evapotranspiration (ET) and soil water dynamics of winter wheat farmland in growing seasons of 2013-2015, then the simulated results were compared against the field experimental data at agrometeorological station in Nanjing, China. Furthermore, separation of soil evaporation and plant transpiration were conducted. Results showed that the R² values between the simulated and measured values reached 0.83 during 2013-2014 and 0.74 during 2014-2015. When the diurnal variation of leaf clumping index and root vertical distribution during the growth stage of the winter wheat was adopted in BEPS, BEPS performed better after modification, with the model efficiency (ME) value increasing from 0.74 to 0.8, the root mean square error (RMSE) value decreasing from 1. 50 mm to 1.05 mm, and the mean bias error (MBE) value decreasing from 0.50 mm to 0.35 mm, respectively. The ratio of soil evaporation to ET changed with growth progress during the growing stage, and the growing seasonaveraged ratios of soil evaporation to ET were 34% and 29% for the two growth seasons, respectively. The BEPS model explained 78% variations of soil moisture in the depth of 0-40 cm, and responded quickly to the change of precipitation. Our study indicates that the improved ecological model can be used to simulate the changes of ET and soil water content in winter wheat farmland, and estimate the ratio between transpiration and evaporation that are difficult to distinguish in crop canopy. Our results will provide a basis for evaluating regional ET and agricultural watersaving management under climate change in the future.

Inversion of chlorophyll-a concentration in nine plateau lakes in Yunnan based on MODIS data.

CHONG Dan1, LI Hao-jie1, FAN Shuo1, LI Jiao-jiao1, WANG Jie2, ZHANG Shi-qiang1*

2017, 36(1):  277-286. 

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Chlorophyll-a concentration is an important parameter reflecting the degree of eutrophication. Based on the field data and MODIS remote sensing data, this study achieved the inversion models of chlorophylla concentration in nine lakes in Yunnan Province. Firstly, the optimum models of each lake in different seasons were established by the combination of the land surface radiation of different bands of MODIS with the measured chlorophyll-a concentration in 2010-2012. Secondly, the inversion models of the nine lakes were validated by using the measured chlorophyll-a concentration from 2013 to 2014. Then, the spatial distributions of chlorophylla concentration in nine lakes were analyzed. The spatial distribution of inversed chlorophyll-a concentration was in accordance with the professional judgment of experts, indicating the inverse models were reasonable. The chlorophyll-a concentrations in Dianchi Lake, Erhai Lake, Chenghai Lake, Qilu Lake, Xingyun Lake, Yilong Lake and Yangzong Lake decreased from the border to the center of lake. However, the chlorophyll-a concentrations in Fuxian Lake and Lugu Lake were higher in the center than in the border of lake. During the period 2010-2014, the concentrations of chlorophyll-a of Dianchi Lake, Erhai Lake, Xingyun Lake and Yilong Lake had larger fluctuation, while those of Fuxian Lake, Chenghai Lake, Qilu Lake and Lugu Lake were relatively stable, and that of Yangzong Lake showed a decreasing trend.