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Table of Content
    Volume 13 Issue 6
    20 November 2005

    The pine wood nematode (Bursaphelenchus xylophilis) can bring about forest degradation, and consequently affect bird communities. The photos show the physiognomy of the Pinus massoniana community infected by the pine wood nematode in Xiangshan County, Zhejiang Province in 2003. For details see pages 496–506 of this issue. (Photographed by Mingjian Yu)

    Large-scale patterns in species diversity of fishes in the Yangtze River Basin
    Xiaodong Yu, Tianhong Luo, Hongzhang Zhou
    Biodiv Sci. 2005, 13 (6):  473-495.  doi:10.1360/biodiv.050121
    Abstract ( 4944 )   PDF (531KB) ( 5476 )   Save
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    We synthesized the information on fish diversity in the Yangtze River Basin, documenting 378 species/subspecies that had been recorded and described from the basin, belonging to 14 orders, 32 families and 144 genera. Of these, 338 species/subspecies are freshwater fishes, of which 269 species/subspecies are from the Cypriniformes. Of the total, 11 species are migratory fishes, and 29 are species of brackish water of the estuary. A total of 162 species/subspecies are endemic to the river and 69 are threatened. We divided the Yangtze River Basin into 19 sub-basins. Except for the two sub-basins of the headwaters and the upper and middle reaches of Jinshajiang River, the other 17 sub-basins showed similar values in species richness and G-F diversity indices, although the values were higher in the upper reaches than in the middle and lower reaches. However, the proportion of endemic species decreased gradually from the headwater to the estuary of the basin in parallel with the gradient of elevation. Jaccard similarity analysis showed that the 19 sub-basins were clustered into three groups: (1) the headwaters and the upper and middle reaches of Jinshajiang River, located in the eastern Qinghai-Xizang Plateau and Hengduan Mountains; (2) the other sub-basins of the upper reaches, located in Western Sichuan Plateau, Yungui Plateau, Sichuan Basin, and Qinling-Daba Mountains; (3) the middle and lower reaches, belonging to the Huaiyang Mountains, Jiangnan Hills and the plain along the middle and lower reaches of the Yangtze River. This grouping reflects the environmental characteristics of the basins and the three large topographic plat-forms of the Chinese mainland.
    Avian community response to vegetation succession caused by the pine wood nematode in Zhejiang, China
    Keyi Jiang, Mingjian Yu, Ping Ding Xuehong Xu, Ping Jiang, Chengmei Zhou, Gao Lu
    Biodiv Sci. 2005, 13 (6):  496-506.  doi:10.1360/biodiv.050068
    Abstract ( 3840 )   PDF (369KB) ( 3046 )   Save
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    The pine wood nematode (Bursaphelenchus xylophilis) has been causing widespread losses to pines in China since it was first found in 1982. It can bring about forest degradation. To study the effect of  nematode-induced forest succession on avian communities, we chose three forest types at different seral stages, including evergreen broad-leaved coppice infested by the pine wood nematode for five years and ev-ergreen broad-leaved forest infested for 12 years, both from Xiangshan County, Zhejiang, and one 40-year-old evergreen broad-leaved forest from Tiantong National Forest Park, Zhejiang. The results showed that bird species richness and diversity were significantly greater in the two infested evergreen broad-leaved forest types with little difference between them, while there existed little difference in bird abundance and evenness in the three types. It suggested that the evergreen broad-leaved forests at early successional stage had higher bird species richness and diversity. Stepwise multiple regression models of bird community vari-ables indicated that microhabitat feature such as stand age was an important predictor of bird community composition.
    Special Issue
    Species diversity of water birds in the wetland of Yueqing Bay, Zhejiang Province
    Yuewei Yang, Guirong Xia, Ping Ding, Renfan Ma, Yuzhao Chen
    Biodiv Sci. 2005, 13 (6):  507-513.  doi:10.1360/biodiv.050044
    Abstract ( 3690 )   PDF (238KB) ( 3486 )   Save
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    We studied the species diversity of water birds in Yueqing Bay in 1997, 1999 and 2003. We observed 54 species of water birds, belonging to 24 genera, seven families and four orders. Number of species and individuals, species diversity index and evenness, and proportion of wader birds decreased from baymouth to bay-head, and was lowest in midbay. The factors affecting bird distribution and diversity were beach width, hydrodynamic conditions and the size of effective upshore intertidal area. In the Yueqing Bay, individual number of water birds tended to decrease year by year,except for those in bay-head, which increased in 2003 over 1999. The decreases between years were insignificant with the exception of baymouth from 1997 to 2003. The decline of bird species diversity and evenness index in Yueqing Bay indicated that the habitats of water birds were being degraded, which might be related to human disturbance such as reclamation.
    Influence of seed predation on regeneration of three Caragana species
    Xiaoying Zhao, Jizhou Ren
    Biodiv Sci. 2005, 13 (6):  514-519.  doi:10.1360/biodiv.050160
    Abstract ( 3512 )   PDF (180KB) ( 2533 )   Save
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    The leguminous Caragana species are important vegetation components, which are useful for rehabilitation of degraded ecosystems on the Loess Plateau, China. We studied the influence of seed predation by frugivores on the regeneration of two native leguminous species, C. licentiana and C. opulens, and one exotic species, C. intermedia. The results showed that before dispersal, 88.2% of the seeds of C. licentiana, 29.7%±1.7% of C. opulens, and 43.2%±4.8% of C. intermedia were infected by insects. After dispersal, 100% of the seeds of C. licentiana and C. opulens in all microhabitat were completely predated by seed predators in one to four days. Seed predation rate of C. intermedia was relatively low and differed with mi-crohabitats: 100% in shrub lands, 85.0%±10.0 in grasslands, and 31.0%±8.7% in open land. Seed predators greatly reduce seed quantity, seed dispersal and germination rate of C. licentiana and C. opulens. On the other hand, seed predators may effectively disperse the hard-coated seeds of C. licentiana, which may ex-plain why C. licentiana has become a dominant shrub species in Dingxi County, Gansu Province. Seed predators have little influence on the seeds of C. intermedia.
    Effects of enclosure protection and seed burial on direct seeding of nut-bearing trees
    Zhishu Xiao, Zhibin Zhang, Yushan Wang
    Biodiv Sci. 2005, 13 (6):  520-526.  doi:10.1360/biodiv.050053
    Abstract ( 3275 )   PDF (122KB) ( 2567 )   Save
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    In a subtropical evergreen broad-leaved forest nearby Dujiangyan City, Sichuan Province, Southwest China, we investigated seedling establishment of six nut-bearing tree species with and without enclosure protection and seed burial, with the aim of determining the impact of these treatments on seed survival and seedling establishment. At the same time, we studied population dynamics of seed-eating rodents in the autumn and the following spring. The results showed that, without enclosure protection, most of the seeds were predated due to high predation pressure in the autumn. The emergence rate of seedlings of all the studied species significantly increased under autumn protection, complete protection, and 1–4 cm burial under soil covered by litter. Effects may reflect the seasonal dynamics of rodent abundance and the characteristics of the seeds. We conclude that taking effective measures such as enclosure protection and seed burial according to seasonal dynamics of rodent population would promote survival after direct seeding.
    Seasonal variation of assembled and naturally recruited plants in a subtropical constructed wetland
    Zhihuan Yang, Ying Ge, Qi Shen, Yueping Jiang, Yuli Tang, Huasheng Wang, Jie Chang
    Biodiv Sci. 2005, 13 (6):  527-534.  doi:10.1360/biodiv.050022
    Abstract ( 3217 )   PDF (284KB) ( 2474 )   Save
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    Constructed wetlands are built mainly for purifying waste water. As a new type of ecosystem, its plant diversity remains unstudied. We studied the seasonal change in plant diversity in a constructed wetland in Hangzhou Botanical Garden, which is located in the humid subtropical area of China. In the autumn of 2002, 72 species were found, of which 18 were assembled and 54 were natural immigrants. In early spring of 2003, the species number was 46 in total, including 33 immigrants. Although naturally recruited plants exceeded the assembled ones in the species number, they were still associated species in the community, in which the assembled species form the dominant components. Some valuable immigrant species should be reserved to enrich biodiversity and to keep the stability of the community. In addition, the co-existence of two functional groups, respectively growing in warm seasons and cold seasons, can effectively occupy the temporal niche-space to prompt the efficiency of nutrient removal and seasonal stability of the constructed wetland.
    Variation of morphological characteristics of Orychophragmus violaceus
    Lijun Zhang, Hongmei Qin, Min Wang, Silan Dai
    Biodiv Sci. 2005, 13 (6):  535-545.  doi:10.1360/biodiv.050126
    Abstract ( 3284 )   PDF (483KB) ( 3554 )   Save
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    Orychophragmus violaceus is widely used for forage, health care and gardening. In order to develop its value,we studied the patterns of its morphological variation. We sampled seven populations from Beijing and Nanjing and measured 34 morphological characters. The results showed that stem height,stem and inflorescent ramification are multiform in different habitats, and therefore have little taxonomic value. The variations of leaf shape, leaf margin and leaf hair are continuous within populations, indicating that they are unreliable for taxonomy. The variations of flowers, including color, size and form of petal are uncontinuous and vary within populations, showing high taxonomic value. The analysis of variation and multiple comparisons of the 17 nu-merical characters indicated that, in the same year, most of these characters are significantly different among populations. In contrast, these differences are inconspicuous between localities. In different years, differences are inconspicuous among populations. Finally, we analysed seven populations and 30 characters using numeri-cal taxonomic methods. Q cluster analysis found that the three populations from the Summer Palace, Zijin Mountain Park and Zhongshan Botanical Garden of Nanjing were grouped together and as were the other four populations. R cluster analysis showed that characters of flower, leaf, and those involving the hair and color of plants were grouped together, respectively, and so were characters involving growth volume.
    ISSR analysis of genetic diversity of Ilex integra, an insular endemic plant
    Xin Leng, Zhongsheng Wang, Shuqing An, Jue Feng, Yuhong Liu, Guoming Wang
    Biodiv Sci. 2005, 13 (6):  546-554.  doi:10.1360/biodiv.050088
    Abstract ( 4266 )   PDF (287KB) ( 3915 )   Save
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    Ilex integra is an insular endemic and endangered species that is distributed only in East Asia. Here we used inter-simple sequence repeat (ISSR) markers to investigate the genetic structure of six populations (five natural populations and one cultivated population) of the species from Zhoushan Archipelago, China. A total of 78 discernible loci were obtained from 57 individuals of all sampled populations using nine primers. Of these loci, 57.7% were polymorphic (PPL=57.7%). Both the average percentage of polymorphic loci (PPL=42.1%) and Nei’s genetic diversity (HE=0.153), estimated by POPGENE, indicated that I. integra had lower levels of genetic diversity than those reported in many other insular plant species. Our results also showed that populations of I. integra were highly differentiated (Gst=0.316, Fst=0.295,S=0.304). Geographic isolation may be a significant factor to the genetic differentiation among these populations. In addition, a significant correlation was found between genetic distance and geographic distance (r=0.649, P<0.05). UPGMA analysis revealed that Putuo Island population had a close relationship with Zhujiajian Island populations, and the cultivated populations on Zhoushan Island might have originated from Taohua Island. Based on the above findings, we propose that conservation management of I. integra should include protection of natural habitats occupied by all five wild populations and preservation of germplasm in bo-tanical gardens from multiple seed sources.
    Impacts of exotic plant invasions on soil biodiversity and ecosystem processes
    Huili Chen, Yujuan Li, Bo Li, Jiakuan Chen, Jihua Wu
    Biodiv Sci. 2005, 13 (6):  555-565.  doi:10.1360/biodiv.050058
    Abstract ( 5634 )   PDF (151KB) ( 5612 )   Save
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    As increasing attention has been paid to below-ground ecosystems in recent years, the impact of exotic plant invasions on soil ecosystems has emerged as a central issue in invasion ecology. In this paper, effects of exotic plant invasions on soil biota and soil nutrient cycling processes are reviewed, and the mechanisms that underlie these impacts are discussed. The available literature suggests that no consistent pattern exists on the impacts of exotic plant invasions on soil microbes, soil animals, soil carbon cycling and nitrogen cycling. The mechanisms underlying the impacts of exotic plant invasions are also complex and diverse. The discrepancies most likely arise from the differences between invasive and native plants in a variety of physiological and ecological traits, such as litter quality and quantity, root distribution, and phenology. Future studies are recommended to (a) compare the impacts across multiple scales and multiple ecosystems; (b) intensify mechanical studies of the impacts; (c) link the impacts on biodiversity and ecosystem processes; and (d) explore the mutualistic interactions between soil ecosystems and exotic plants.

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