人類活動引起的植物功能群的喪失對生態(tài)系統(tǒng)性質(zhì)和功能的影響是生態(tài)學研究的重要問題之一,。由于生態(tài)系統(tǒng)地上部分與地下部分緊密相關(guān),，植物功能群的喪失必然會影響地下群落的特性和功能。但是,，植物功能群的喪失如何影響土壤微生物的群落結(jié)構(gòu)和功能往往被忽視,。因此，開展相關(guān)的研究對生態(tài)學理論和人工林經(jīng)營管理都具有重要的意義,。
中科院華南植物園恢復(fù)生態(tài)學研究團隊博士生吳建平和劉占鋒博士等在傅聲雷研究員的指導下,，以2年和24年的桉樹人工林為研究對象，采用莖干環(huán)割和林下灌草去除的方法研究了植物功能群去除對土壤微生物群落結(jié)構(gòu)及其分解功能的影響,。結(jié)果表明：林下灌草去除顯著降低土壤中真菌的生物量及真菌/細菌比值,，但對細菌和微生物生物量總量影響不顯著，這主要是土壤微環(huán)境的改變所致,。同時,，林下灌草去除引起的土壤微生物群落結(jié)構(gòu)的改變顯著減緩凋落物的分解；相反,，莖干環(huán)割對土壤微生物的影響不明顯,，這主要是因為桉樹的萌發(fā)特性或菌根真菌的相互作用造成的。
該研究表明,，作為亞熱帶人工林的重要組成部分,，林下灌草在維持土壤微生物群落結(jié)構(gòu)和功能方面發(fā)揮著重要的作用，并且在幼年林和成熟林中扮演不同角色,。本研究首次從地下碳輸入的角度將喬木樹種和林下植被在驅(qū)動土壤微生物群落結(jié)構(gòu)與功能方面的相對貢獻區(qū)分開,，相關(guān)研究結(jié)果已經(jīng)在生態(tài)學研究領(lǐng)域主流期刊Functional Ecology上在線發(fā)表。（生物谷Bioon.com）
生物谷推薦原文出處：
Functional Ecology DOI: 10.1111/j.1365-2435.2011.01845.x
Effects of understory removal and tree girdling on soil microbial community composition and litter decomposition in two Eucalyptus plantations in South China
Jianping Wu1,2,?, Zhanfeng Liu1,?, Xiaoling Wang1,2, Yuxin Sun2,3, Lixia Zhou1, Yongbiao Lin1, Shenglei Fu1,*
Keywords:Eucalyptus;forest management;girdling;phospholipid fatty acids;principal response curves;redundancy analysis;understory
Summary
1. Soil micro-organisms play important roles in ecosystems and respond quickly to environmental changes. We examined how understory removal and tree girdling influence the composition of soil microbial community and the litter decomposition in two subtropical plantations.
2. Phospholipid fatty acids (PLFAs) analysis was used to characterize soil microbial community. Redundancy analysis and principal response curves (PRC) were used to investigate the relationships between soil microbial community and environmental factors.
3. Understory removal significantly reduced the amount of fungal PLFAs, the ratio of fungal to bacterial PLFAs, and the litter decomposition but did not affect bacterial PLFAs and total PLFAs. In contrast, tree girdling did not affect the soil microbial characteristics. The changes in soil microbial community caused by understory removal were mainly attributed to the indirect effects such as increased soil temperature and soil NO3?-N availability. In addition, PRC analysis showed that the relative abundance of most PLFAs increased in response to understory removal in the 2-year-old plantation but decreased in the 24-year-old plantation.
4. We propose that understory plants are important components in subtropical forest ecosystems, and play different roles in maintaining soil microbial community and driving litter decomposition processes in young vs. old plantations. The functions of understory plants should be considered in forest management and restoration. The negligible effect of tree girdling on the soil micro-organisms can be attributed to the resprouting trait and mycorrhizal interactions of Eucalyptus.
