近日,，國際雜志Oikos刊登了中國科學(xué)院西雙版納熱帶植物園胡躍華博士等的最新研究成果“Dominant species and dispersal limitation regulate tree species distributions in a 20-ha plot in Xishuangbanna, southwest China,。”,，研究人員在物種共存機(jī)制上的研究獲新進(jìn)展。
熱帶森林高多樣性的物種如何共存,？群落生態(tài)學(xué)當(dāng)中主流的生態(tài)位分化理論和中性理論都分別試圖解釋物種共存的機(jī)制,，盡管在世界多個大型固定樣地得到不同程度的驗證，卻難以完全解釋這一核心問題,。目前,，大部分生態(tài)學(xué)家傾向于將此二者相結(jié)合，但是生態(tài)位主導(dǎo),、作用相當(dāng)還是中性主導(dǎo),？基于此，西雙版納20公頃大樣地喬木樹種分布的最新研究結(jié)果給出一些新的解讀,。
中國科學(xué)院西雙版納熱帶植物園胡躍華博士等對西雙版納20公頃大樣地喬木樹種分布研究發(fā)現(xiàn)：生態(tài)位和中性過程對于物種共存的貢獻(xiàn)并不是一個簡單的孰大孰小問題,。對于具有較長生活史的喬木樹種而言，在其各個生活史階段生態(tài)位和中性過程的相對重要性是不斷變化的——中性過程在小徑級的幼樹階段占優(yōu),；隨著徑級增大,，生態(tài)位過程在成年大樹階段起主導(dǎo)作用。這是因為幼樹的分布與種子的散布過程緊密相關(guān),，而種子的散布過程具有極強(qiáng)的隨機(jī)性，因此中性散布過程主導(dǎo)了幼樹的空間分布,；由于空間的異質(zhì)性分化,，從幼樹到大樹的過程中，環(huán)境的過濾作用逐漸成為物種分布的決定因素,，大樹的分布與環(huán)境異質(zhì)性相關(guān)性增強(qiáng),，所以生態(tài)位過程決定了大樹的分布。（生物谷Bioon.com）
doi:10.1111/j.1600-0706.2011.19831.x
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Dominant species and dispersal limitation regulate tree species distributions in a 20-ha plot in Xishuangbanna, southwest China
Yue-Hua Hu, Li-Qing Sha, F. Guillaume Blanchet, Jiao-Lin Zhang, Yong Tang, Guo-Yu Lan and Min Cao
Habitat heterogeneity and dispersal limitation are widely considered to be the two major mechanisms in determining tree species distributions. However, few studies have quantified the relative importance of these two mechanisms at different life stages of trees. Moreover, rigorous quantification of the effects of dominant tree species in determining species distributions has seldom been explored. In the present study, we tested the hypothesis that the distribution of tree species is regulated by different mechanisms at different life history stages. In particular, we hypothesised that dispersal limitation regulates the distribution of trees at early life stages and that environmental factors control the distribution of trees as they grow, because of niche differentiation resulting from environmental filtering. To test this, trees in 400-m2 quadrats in a 20-ha plot in Xishuangbanna, southwest China were grouped into four classes on the basis of the diameter at breast height (DBH) that roughly represent different stages in the life history of trees. A neighbourhood index was computed to represent a neutral spatial autocorrelation effect. We used both biotic (dominant species) and abiotic (topography and soil) predictor variables to model the distribution of each target species while controlling for spatial autocorrelation within each of the DBH classes. To determine which factors played the largest role in regulating target species distribution, the simulated annealing method was used in model selection based on Akaike information criterion (AIC) values. The results showed that the relative importance of neutral and niche processes in regulating species distribution varied across life stages. The neutral neighbourhood index played the most important role in determining the distributions of small trees (1 cm ≤ DBH ≤ 10 cm), and dominant species, as biotic environmental predictor variables, were the next most important regulators for trees of this size. Environmental predictor variables played the most important role in determining the distributions of large trees (10 cm ≤ DBH). This finding builds on previous research into the relative importance of neutral and niche processes in determining species distributions regardless of life stages or DBH classes.
