灌木柴桦在我国高纬度地区湿地生态系统迅速扩张生境的机制

Rapid plant range-expanding induced by climate warming is similar with the process of alien plant invasion, so the range-expanding plant species are also defined as native invaders. Although many important hypotheses are proposed to explain alien plant invasion, it is still unclear whether they can explain the rapid range-expanding of plant species. The present proposal will do a case study using the range-expanding shrub Betula fruticose to test whether hypotheses in alien plant invasion can explain the mechanism of native plant invasion. A climate warming facility will be setup at a wetland site in the high latitudes of China, where the shrub B. fruticose is not invaded now. Seeds of the shrub B. fruticose will be introduced to the ambient and warming plots. Seed germination, seedling survive and performance of the shrub will be measured to test whether the climate warming increase the environmental suitability for its invasion. Using the activated carbon addition approach, a controlled greenhouse experiment will be conducted to test the potential allelopathy of the shrub B. fruticose and other native herbaceous plants on each other, and test whether the allelopathy play an important role during invasion of the shrub B. fruticose. Using the stable nitrogen isotope labeling approach, a field experiment will be conducted to compare the nitrogen uptake rates between the shrub B. fruticose and the native herbaceous communities. It will be used to answer the last question whether differences of nitrogen uptake rate between the shrub B. fruticose and other native herbaceous communities play an important role on the shrub invasion. Taken together, mechanism for rapid expansion of the shrub B. fruticose across wetland ecosystem in the high latitudes of China will be answered in the present proposal.

全球气候变暖导致的本地植物生境扩张也属于广义的植物入侵生态学范畴，即本地植物入侵。尽管已经有很多重要假说来解释外来植物入侵机理，但尚不清楚这些假说是否可以解释本地植物入侵，即外来植物入侵假说是否可以解释全球变暖引起的本地植物生境扩张。本项目以我国高纬度地区的生境扩张灌木柴桦(Betula fruticose)为例，在柴桦未入侵的湿地生态系统草本植物群落设置原位增温平台，进行柴桦引种实验，验证增温引起的综合环境适宜性对柴桦种子萌发和幼苗建植的重要性；利用活性炭粉末添加方法和温室控制实验，对柴桦和该湿地生态系统典型土著草本群落进行相互化感作用对比，验证化感作用在柴桦入侵过程的重要性；利用稳定性氮同位素标记技术对柴桦与土著植物群落氮吸收速率进行对比，验证养分获取能力在柴桦入侵过程的重要性。以此，综合探讨本地入侵灌木柴桦在高纬度湿地生态系统草本群落不断拓展生境的内在机制。

本地植物生境快速扩张过程与外来植物入侵过程类似，都属于广义的植物入侵生态学范畴。尽管在入侵生态学领域已有许多重要假说解释外来植物入侵机制，但是尚不清楚这些假说是否可以同样解释本地植物生境扩张。本项目以我国高纬度地区的生境扩张灌木柴桦（Betula fruticosa）为研究对象，探讨了增温对柴桦在湿地草本群落建植的影响，发现增温背景下的干旱可以降低草本植物群落的丰富度和多度，进而促进灌木扩张；研究了柴桦与湿地草本植物群落的相互化感作用，发现湿地草本植物群落与柴桦之间存在不对称的化感作用，草本群落可以通过化感作用抑制柴桦生长，进而阻碍其向湿地草本植物群落扩张；并进一步检验了柴桦与湿地草本群落氮竞争能力差异，发现干旱为灌木向湿地草本植物群落的扩张提供了基础条件，即提高了灌木种子的萌发和成活率，而灌木建殖之后，氮添加增加了灌木幼苗的竞争优势，促进其在草本植物群落中扩张。

内容获取失败，请点击重试