Читать книгу Wetland Carbon and Environmental Management - Группа авторов - Страница 46

Climate regulation by wetlands is an important ecosystem service that is increasingly a focus of management and restoration efforts (Erwin, 2009; Moomaw et al., 2018). The basis for these efforts is the observation that wetlands have accumulated globally significant amounts of organic carbon in their soils (Mitra et al., 2005), carbon (C) that is no longer in the atmosphere as the greenhouse gas carbon dioxide (CO₂). It is becoming apparent that much of the organic carbon preserved in wetlands is not inherently resistant to decay but instead accumulates because its reactivity is reduced under the environmental conditions in wetland soils (e.g., Spivak et al., 2019). An important corollary of this understanding is that changes to the wetland environment (e.g., as initiated through management decisions or disturbances) could alter those conditions, thus destabilizing the large wetland carbon stores and allowing their export to adjacent aquatic systems as dissolved or particulate carbon or their return to the atmosphere as CO₂ and methane (CH₄). Further, some of the wetland conditions that promote carbon preservation also lead to the production of the greenhouse gases CH₄ and nitrous oxide (N₂O), the emissions of which can offset some or all of the climatic benefits provided by wetland carbon preservation.

Environmental management and other human actions, whether purposeful or accidental, can affect the pathways of carbon preservation and removal and therefore have the potential to alter the effects of wetlands on the global climate. In this chapter, we briefly summarize (1) the concepts of radiative balance and radiative forcing as ways of describing how ecosystems and management actions influence the climate. We then address (2) the factors that control wetland carbon preservation. The term “carbon preservation,” which we use throughout this chapter, is largely synonymous with “carbon sequestration” and “carbon storage.” We use preservation to emphasize the absence of decomposition; this framework has helped us think about the processes and mechanisms in a slightly different way. After discussing carbon preservation, we review (3) the processes leading to emissions of greenhouse gases and other losses of carbon from wetlands, before discussing (4) how wetland management can be used to manipulate those biogeochemical factors that affect wetland carbon preservation and flux. We offer this synthesis in the hopes that it will help guide wise decisions.