XTBG OpenIR  > 西双版纳热带植物园毕业生学位论文
西双版纳热带季节雨林中的板根及其对凋落物分解的影响
何智媛
Subtype硕士
Thesis Advisor唐勇
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline生态学
Other Abstract板根现象虽然在热带雨林中普遍存在,但到目前为止,对板根存在的普遍性及其生态学功能仍缺乏系统的认识。本研究在对西双版纳20-ha热带季节雨林大样地中板根进行系统调查的基础上探讨板根形成机制及其对热带雨林生境异质性的贡献,并结合板根树与非板根树基部上下坡位的凋落叶分解实验,来回答以下问题:1)西双版纳热带季节雨林中不同分类水平上的板根发生率如何?影响板根形成的因素有哪些?2)板根结构存在后形成了怎样的微生境?3)这种微生境对凋落物分解有何影响? 调查结果显示,西双版纳热带季节雨林虽然地处热带北缘,板根普遍存在,但不如赤道地区热带雨林中的板根典型。20公顷的热带季节雨林大样地468个树种中有241个树种具有形成板根的个体(51%),95940个DBH≥10mm的个体中有4669个发育出了板根(5%),而DBH≥ 100mm的个体中具有板根的个体达到32%。不同科属、不同种、同一种内不同个体在板根形成倾向上常不一致,这表明板根的形成不具有物种特异性,胸径大的物种和个体更容易形成,板根系统发育分析表明亲缘关系近的物种有相似的形成板根的潜力。 板根促进了植物个体基部与其所处环境间的交互作用,与非板根树相比板根树基部的上下坡位间形成了较非板根树更高的土壤养分梯度(主要体现在土壤总碳、总氮、有机碳和水解氮上)和地表凋落物积累量上的差异。这种交互作用可能主要通过板根结构对于来自上坡位的凋落物、土壤颗粒、地表径流等的拦截作用实现,从而在热带雨林中形成异质性的生境。 板根在其树干基部上下坡位间形成的微生境对凋落物分解速率的影响主要体现在雨季初期的凋落物分解高峰期(4月到6月,上下坡位的分解速率常数分别为7.08±0.46yr-1和5.83±0.37yr-1),而在分解后期及后来雨季中期(8月)、旱季中期(12月)的分解过程中均未检测到分解速率上的差异。而非板根树基部的上下坡位间在不同季节均未表现出分解速率上的差异。这些结果表明,坡地条件下板根与地形交互作用在降雨丰沛、地表凋落物大量积累时对凋落物分解速率有较强的影响。 本研究的结果支持板根是大乔木的支撑器官的假说,同时显示板根的形成可能受到遗传和环境诱导的双重作用。板根形成的异质性生境及其在凋落物分解等生态过程中的作用表明板根可能在热带雨林生物多样性的维持中起着重要的作用; Buttresses are prevalent in tropical rainforest but are largely overlooked in rainforest studies. The origin and ecological functions of buttresses are still unclear. Based on a buttress survey conducted in a 20-ha tropical seasonal rainforest in Xishuangbanna, SW. China, this study attempt to discuss the underlying mechanism of buttress formation and the contribution buttresses to rainforest habitat heterogeneity. In addition, a litter decomposition experiment was conducted to compare the litter decomposition rate around the base of buttress and non-buttress trees. This study aimed at answering following questions: 1) What is buttress occurring rate among different taxa and what factors affect buttress forming? 2) If buttresses affect the microhabitat around trees? 3) If the microhabitat around buttress trees affect litter decomposition? The buttress survey showed that buttresses were abundant in this tropical seasonal rainforest which is situated at the northern edge of the tropics. However, buttresses were relatively smaller than those found in equatorial rainforests. Among the 468 tree species (DBH≥ 10mm) in the 20-ha plot, 241 species (51%) had individuals developed buttresses. Thirty two percent of trees( DBH≥ 100 mm) developed buttresses. Buttresses occurred in broad unrelated taxa and both buttress and non-buttress trees were found in different families, genera and even within the same species. Buttress formation was clearly not species specific despite there was strong phylogenetic signal across different taxa. Large sized species and individuals were most likely to develop buttresses. Buttresses interact with environment factors and showed an impact on the micro-environment near the tree bases. Higher levels of soil nutrients gradient (maily on total carbon, total nitrogen, organic carbon and hydrolysable nitrogen) and surface litter fall accumulation gradient were found between upslope and downslope side of buttress trees compared with non-buttress trees. Those differences may be caused by the interception of matter flow such as litter fall, soil particle, ground runoff, from up to down slopes near buttresses. The microhabitats formed near the buttress trees showed an influence on litter decomposition. A higher litter decomposition rate was found at the upslope side of the buttress tree at the beginning of rainy season (from April to June) and the k value of decomposition were 7.08±0.46yr-1and 5.83±0.37yr-1 at the upslope and downslope sides of buttress trees, respectively. However, no difference was found at other times. In addition, there was no difference in litter decomposition rate between the upslope and downslope sides of non-buttress trees. This influence on litter decomposition was caused by interaction of buttress with topography during the period of time when high rainfall and high litter fall accumulation occurred. The results from this study support the hypothesis that buttresses are structural supporting organs of large trees and their formation may be inherited and induced by environmental factors. Buttress may play important roles in the maintenance of rainforest diversity by contributing to environmental heterogeneity and influencing on ecological processes such as litter decomposition.
Document Type学位论文
Identifierhttp://ir.xtbg.org.cn/handle/353005/10694
Collection西双版纳热带植物园毕业生学位论文
Recommended Citation
GB/T 7714
何智媛. 西双版纳热带季节雨林中的板根及其对凋落物分解的影响[D]. 北京. 中国科学院研究生院,2013.
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