Zou Yi, Sang Weiguo, Bai Fan, Axmacher Jan Christoph
UCL Department of Geography, University College London, London, United Kingdom.
The State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China ; College of Life and Environmental Science, Minzu University of China, Beijing, China.
PLoS One. 2013 Dec 20;8(12):e82792. doi: 10.1371/journal.pone.0082792. eCollection 2013.
A positive relationship between plant diversity and both abundance and diversity of predatory arthropods is postulated by the Enemies Hypothesis, a central ecological top-down control hypothesis. It has been supported by experimental studies and investigations of agricultural and grassland ecosystems, while evidence from more complex mature forest ecosystems is limited. Our study was conducted on Changbai Mountain in one of the last remaining large pristine temperate forest environments in China. We used predatory ground beetles (Coleoptera: Carabidae) as target taxon to establish the relationship between phytodiversity and their activity abundance and diversity. Results showed that elevation was the only variable included in both models predicting carabid activity abundance and α-diversity. Shrub diversity was negatively and herb diversity positively correlated with beetle abundance, while shrub diversity was positively correlated with beetle α-diversity. Within the different forest types, a negative relationship between plant diversity and carabid activity abundance was observed, which stands in direct contrast to the Enemies Hypothesis. Furthermore, plant species density did not predict carabid α-diversity. In addition, the density of herbs, which is commonly believed to influence carabid movement, had little impact on the beetle activity abundance recorded on Changbai Mountain. Our study indicates that in a relatively large and heterogeneous mature forest area, relationships between plant and carabid diversity are driven by variations in environmental factors linked with altitudinal change. In addition, traditional top-down control theories that are suitable in explaining diversity patterns in ecosystems of low diversity appear to play a much less pronounced role in highly complex forest ecosystems.
“天敌假说”是生态学中一个核心的自上而下控制假说，该假说假定植物多样性与捕食性节肢动物的丰度和多样性之间存在正相关关系。这一假说已得到农业和草原生态系统实验研究及调查的支持，但来自更复杂的成熟森林生态系统的证据有限。我们的研究在中国最后留存的大型原始温带森林环境之一的长白山进行。我们以捕食性步甲（鞘翅目：步甲科）作为目标分类群，来确定植物多样性与其活动丰度和多样性之间的关系。结果表明，海拔是预测步甲活动丰度和α多样性的两个模型中唯一包含的变量。灌木多样性与步甲丰度呈负相关，草本多样性与步甲丰度呈正相关，而灌木多样性与步甲α多样性呈正相关。在不同的森林类型中，观察到植物多样性与步甲活动丰度之间存在负相关关系，这与“天敌假说”形成直接对比。此外，植物物种密度并不能预测步甲的α多样性。此外，通常认为会影响步甲活动的草本植物密度，对长白山记录的步甲活动丰度影响很小。我们的研究表明，在一个相对较大且异质性的成熟森林区域，植物与步甲多样性之间的关系是由与海拔变化相关的环境因素变化驱动的。此外，适用于解释低多样性生态系统中多样性模式的传统自上而下控制理论，在高度复杂的森林生态系统中似乎作用甚微。
