Viketoft Maria, Bengtsson Janne, Sohlenius Björn, Berg Matty P, Petchey Owen, Palmborg Cecilia, Huss-Danell Kerstin
Department of Ecology, Swedish University of Agricultural Sciences (SLU), Box 7044, SE-750 07 Uppsala, Sweden.
Ecology. 2009 Jan;90(1):90-9. doi: 10.1890/08-0382.1.
An important component of plant-soil feedbacks is how plant species identity anddiversity influence soil organism communities. We examine the effects of grassland plant species growing alone and together up to a richness of 12 species on nematode diversity and feeding group composition, eight years after the establishment of experimental grassland plots at the BIODEPTH site in northern Sweden. This is a substantially longer time than most other experimental studies of plant effects on soil fauna. We address the hypotheses that (la) higher species or functional diversity of plants increases nematode diversity, as well as influences nematode community composition. Alternatively, (1b) individual plant species traits are most important for nematode diversity and community composition. (2) Plant effects on soil organisms will decrease with increasing number of trophic links between plants and soil fauna. Plant species identity was often more important than plant diversity for nematode community composition, supporting hypothesis 1b. There was a weak positive relation between plant and nematode richness;which could be attributed to the presence of the legume Trifolium pratense, but also to some other plant species, suggesting a selection or sampling effect. Several plant species in different functional groups affected nematode community composition. For example, we found that legumes increased bacterial-feeding nematodes, most notably r-selected Rhabditida, while fungal-feeding nematodes were enhanced by forbs. Other bacterial feeders and obligate root feeders were positively related to grasses. Plant effects were usually stronger on plant-, bacterial- and fungal-feeding nematodes than on omnivores/predators, which supports hypothesis 2. Our study suggests that plant identity has stronger effects than plant diversity on nematode community composition, but when comparing our results with similar previous studies the effects of particular plant species appear to vary. We also found that more productive plant species affected bacterial-feeding nematodes more than fungal feeders. Moreover, we observed stronger effects the fewer the number of trophic links there were between a nematode feeding group and plants. Although we found clear effects of plants on soil nematodes, these were probably not large enough to result in strong and persistent plant-soil-organism-plant feedback loops.
植物 - 土壤反馈的一个重要组成部分是植物物种的身份和多样性如何影响土壤生物群落。我们在瑞典北部BIODEPTH站点的实验性草地地块建立八年后,研究了单一生长以及多达12种植物共同生长的草地植物物种对线虫多样性和取食类群组成的影响。这一时间比大多数其他关于植物对土壤动物影响的实验研究长得多。我们探讨了以下假设:(1a)植物更高的物种或功能多样性会增加线虫多样性,并影响线虫群落组成。或者,(1b)单个植物物种的特性对线虫多样性和群落组成最为重要。(2)随着植物与土壤动物之间营养联系数量的增加,植物对土壤生物的影响将减弱。对于线虫群落组成而言,植物物种身份通常比植物多样性更重要,这支持了假设1b。植物丰富度与线虫丰富度之间存在微弱的正相关关系;这可能归因于豆科植物红车轴草的存在,但也与其他一些植物物种有关,表明存在选择或抽样效应。不同功能组中的几种植物物种影响了线虫群落组成。例如,我们发现豆科植物增加了以细菌为食的线虫,最显著的是r选择型的小杆线虫目,而以真菌为食的线虫则因草本植物而增加。其他以细菌为食的线虫和专性根食性线虫与禾本科植物呈正相关。植物对以植物、细菌和真菌为食的线虫的影响通常比对杂食性/捕食性线虫的影响更强,这支持了假设2。我们的研究表明,植物身份对线虫群落组成的影响比植物多样性更强,但将我们的结果与之前类似的研究进行比较时,特定植物物种的影响似乎有所不同。我们还发现,生产力更高的植物物种对以细菌为食的线虫的影响比对以真菌为食的线虫的影响更大。此外,我们观察到,线虫取食类群与植物之间的营养联系数量越少,影响越强。尽管我们发现植物对土壤线虫有明显影响,但这些影响可能不足以导致强烈且持久的植物 - 土壤生物 - 植物反馈循环。