Abstract:

Ectomycorrhiza (ECM) are symbionts formed between soil fungi and plant root systems, in which the fungus exchanges soil-derived nutrients for carbohydrates obtained from the host plant. As an important component of terrestrial ecosystems, ECM fungi can play an essential role in biodiversity maintenance and plant community succession. Understanding the distribution pattern and maintenance of ECM fungal diversity is therefore critical to the study of biodiversity and ecosystem functioning. An analysis of results of recent research indicates that ECM fungal diversity increases with increasing latitude, i.e. from tropical to subtropical and temperate regions. The role of dispersal in ECM fungal distribution is dependent on spatial scale. Thus, it has been found to be weak across global and local scales, but strong at regional and small scales. At the local scale, its influence has also been shown to be host-dominant dependent; thus, it is important in host non-dominant ecosystems, but not in host dominant ecosystems. Selection by plant, animal, microbe and abiotic factors can also affect the distribution pattern of ECM fungi, according to studies of temperate ecosystems. In contrast, studies of tropical ecosystems indicate that selection on ECM fungal distribution can be either strong or weak. ECM fungal diversity is also influenced by plant diversity and productivity. The plant diversity hypothesis at host genus-level fits well with ECM fungal diversity in temperate, subtropical and tropical forest ecosystems; in contrast, the productivity diversity hypothesis is only supported by some studies in temperate forest ecosystems. We propose that future studies should focus on the distribution pattern, maintenance mechanism and ecosystem function of ECM fungal diversity at a global scale, taking account of scenarios of global climate change.

Key words: selection, dispersal, spatial scale dependence, host dominant dependence, plant diversity hypothesis, productivity diversity hypothesis