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831.
《植物生态学报》2017,41(12):1219
Aims Interspecific associations can reflect how species are assembled into communities. The objectives of this study were to examine the patterns of woody species co-occurrence and to determine how species’ abundance would affect species associations. Methods Data from a total of 23 plots were used to test the interspecific associations of 93 woody plant species in forest communities of Putuoshan Island in Zhejiang Province. We compared the observed species associations with the expected patterns at random, and correlated interspecific association intensities with co-dominance propensity of species pairs. Important findings Species distribution co-varied among plots at the spatial scale of either 10 m × 10 m or 20 m × 20 m, but the majority of the 4 278 species pairs were not significantly associated. Interspecific association intensities were positively correlated with co-dominance propensity of species pairs, indicating that species abundance is a key factor affecting the interspecific co-occurrence. The observed values of variance ratio and the proportion of significantly associated species pairs consistently fell outside of the 2.5th-97.5th percentiles of random expectations (i.e. randomly permuting species across plots), suggesting that deterministic processes also play a role in species associations on the Putuoshan Island. We conclude that the pattern of woody species co-occurrence on Putuoshan Island are structured by both niche and stochastic processes. 相似文献
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Hatem Zgallai Kathy Steppe Raoul Lemeur 《植物学报(英文版)》2006,48(6):679-685
A greenhouse experlment was performed In order to Investigate the effects of dlfferent levels of water stress on leaf water potentlal (ψw), stomatal resistance (rs), protein content and chlorophyll (Chl) content of tomato plants (Lycoperslcon esculentum Mill. cv. Nlkita). Water stress was Induced by addlng polyethylene glycol (PEG 6 000) to the nutrlent solution to reduce the osmotlc potential (ψs). We Investlgated the behavlor of antl-oxldant enzymes, such as catalase (CAT) and superoxide dlsmutase (SOD), durlng the development of water stress. Moderate and severe water stress (i.e. ψs= -0.51 and -1.22 MPa, respectlvely) caused a decrease In ψw for all treated (water-stressed) plants compared with control plants, wlth the reductlon belng more pronounced for severely stressed plants. In addltion, rs was slgnlflcantly affected by the Induced water stress and a decrease in leaf soluble protelns and Chl content was observed. Whereas CAT actlvlty remained constant, SOD actlvlty was increased in water-stressed plants compared wlth unstressed plants. These results Indicate the possible role of SOD as an anti-oxidant protector system for plants under water stress condltlons. Moreover, It suggests the possibllity of using this enzyme as an addltional screening crlterlon for detecting water stress in plants. 相似文献