图 书 馆
森林食物网动态——特别强调土壤生物区系Forest food web dynamics with special emphasis on soil biota |
|
| 课程网址: | http://videolectures.net/bzid2011_setala_biota/ |
| 主讲教师: | Heikki Setälä |
| 开课单位: | 赫尔辛基大学 |
| 开课时间: | 2011-10-21 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | The dynamics of forests are commonly considered from the above-ground point of view, where plants, mostly trees, are believed to play a regulative role. Accumulating amount of evidence suggests, however, that the organisms of the below-ground food webs can pose a strong control over the various phenomena in the forests, most importantly forest productivity. As soil saprophytic microbes, such as fungi and bacteria, comprise up to 98% of the total biomass of the forest soil food webs they are often considered to play a decisive role as affecting the decomposition rate of dead organic matter and liberating growth-limiting nutrients, such as nitrogen and phosphorus, for the uptake by forest trees. This belief is, however, not necessarily true and it has been challenged by a multitude of experiments conducted in small-scale experiments under laboratory conditions. Based on the studies that I have conducted with my research group since late eighties, I will present evidence showing that, by feeding upon soil saprophytic microbes, soil fauna stimulate the activity of soil microbes and thereby pose a strong effect on decomposition processes in forest soils. I will also show that soil fungal-feeding fauna can affect the growth and activity of ectomycorrhizal fungi on the plant roots and that this interaction can be beneficial for tree growth. Results of these studies suggest that it is the functional group (such as fungal feeders, bacterial feeders, detritus feeders, predators) diversity of soil fauna and microbes, rather than species diversity of the two groups, that control below-ground processes and plant growth. However, some species, such as the enchytraeid worm Cognettia sphagnetorum, are more influential than others and can deserve the status of a key-stone species in the forest. The absence of such taxa can lead to changes in the nutrient content of plants which can reflect in the performance of plant foliage-eating insects above the ground. It is concluded that to fully understand the dynamics and well-being of forest ecosystems it is essential to recognise that these ecosystems are driven by the mutualistic feedback apparatus existing between soil biota and the organisms living above the ground. |
| 关 键 词: | 森林; 植物生长; 食物链; 土壤结构; 土壤生物; 森林生态环境 |
| 课程来源: | 视频讲座网 |
| 最后编审: | 2019-10-22：cwx |
| 阅读次数: | 67 |