Ectomycorrhizal (ECM) fungi are a group of cosmopolitan symbiotic soil fungi that colonize the fine roots of tree species and play an essential role in plant nutrition and ecosystem function. In worldwide afforestation projects, the establishment of introduced trees in novel habitats has been shown to require ECM fungal associations. The process for these introduced trees to establish is complicated by evolutionary host-partner specificity and nutrient allocation strategies. In each experiment of this dissertation, colonization of native Pinus massoniana (MP) and introduced Pinus elliottii (SP) by ECM fungi was used along with morphological and molecular sampling methods to measure ECM community characteristics. Chapter I investigates which sampling scenarios would best resolve and describe the ECM fungal communities using high throughput sequencing (HTS). The results indicated a) analyzing a ‘mock’ community of known taxa with HTS was important for determining operational taxonomic unit (OTU) clustering and setting OTU low abundance read filtering; b) sampling protocols (replications, etc.) could optimize the recovery of OTU richness, but the documentation of the effect on beta-diversity by prior effects (e.g. forest types of different hosts) was not influenced; and c) different sampling resources (in-growth bag vs. root tips) of ECM fungi revealed significant difference in recovered ECM fungal communities by HTS. In Chapter II, I examined ECM fungal communities and soil physio-chemical properties of both MP and SP forest across broad geographic ranges of south China. This field investigation showed that large-scale geographic processes and edaphic condition set the regional species pool, whereas host specificity defined abundance and composition of ECM fungal species associated with native or introduced hosts at local scales. For Chapter III, I monitored the ECM fungal community succession on native and introduced pine seedlings through a reciprocal bioassay experiment, which incorporated the combinations of different soil environment and ECM fungal inoculum resources. I found that the early establishment of ECM fungi was differentiated by host seedling identity. This pattern was further elucidated in Chapter IV where ECM fungi communities associated with native MP versus introduced SP seedlings displayed different exoenyzme functions, and those functional groups highly correlated with host identity and nutrient status. ECM fungi were also important for co-adaptation of host trees grown in the local soil compared with those grown in novel combinations. This research suggests that host identity, especially of introduced tree species, should be addressed in woodland restoration projects, and that more work is necessary to determine how best to restore ECM communities and the nutrient cycling patterns in local ecosystems.

Last modified

• 11/24/2019

Creator

• Chen Ning

DOI

• https://doi.org/10.21985/n2-j366-5n28

Subject

• Plant Biology and Conversation

Keyword

• pinus
• ectomycorrhiza
• fungal community
• forest soil
• exotic tree
• enzyme

Date created

• 2018-01-01

Resource type

• Dissertation

Rights statement

• In Copyright