Distribution patterns and environmental drivers of methane cycling microorganisms in natural environments and restored wetlands Methane is an important greenhouse gas contributing to global climate change. Natural environments and restored wetlands contribute a large proportion to the global methane budget. Methanogenic archaea (methanogens) and methane oxidizing bacteria (methanotrophs) the biogenic producers and consumers of methane play key roles in the methane cycle in those environments. A large number of studies revealed the distribution diversity and composition of these microorganisms in individual habitats. However uncertainties exist in predicting the response and feedback of methane cycling microorganisms to future climate changes and related environmental changes due to the limited spatial scales considered so far and due to a poor recognition of the biogeography of these important microorganisms combining global and local scales. With the aim of improving our understanding about whether and how methane cycling microbial communities will be affected by a series of dynamic environmental factors in response to climate change this PhD thesis ...