Effects of water level alteration on carbon cycling in peatlands

Globally,peatlands play an important role in the carbon(C)cycle.High water level is a key factor in maintaining C storage in peatlands,but water levels are vulnerable to climate change and anthropogenic disturbance.This review examines literature related to the effects of water level alteration on C cycling in peatlands to summarize new ideas and uncertainties emerging in this field.Peatland ecosystems maintain their function by altering plant community structure to adapt to changing water levels.Regarding primary production,woody plants are more productive in unflooded,well-aerated conditions,while Sphagnum mosses are more productive in wetter conditions.The responses of sedges to water level alteration are species-specific.While peat decomposition is faster in unflooded,well aerated conditions,increased plant production may counteract the C loss induced by increased ecosystem respiration(ER)for a period of time.In contrast,rising water table maintains anaerobic conditions and enhances the role of the peatland as a C sink.Nevertheless,changes in DOC flux during water level fluctuation is complicated and depends on the interactions of flooding with environment.Notably,vegetation also plays a role in C flux but particular species vary in their ability to sequester and transport C.Bog ecosystems have a greater resilience to water level alteration than fens,due to differences in biogeochemical responses to hydrology.The full understanding of the role of peatlands in global C cycling deserves much more study due to uncertainties of vegetation feedbacks,peat-water interactions,microbial mediation of vegetation,wildfire,and functional responses after hydrologic restoration.

Functional integrity of freshwater forested wetlands,hydrologic alteration,and climate change

Climate change will challenge managers to balance the freshwater needs of humans and wet-lands.The Intergovernmental Panel on Climate Change predicts that most regions of the world will be exposed to higher temperatures,CO2,and more erratic precipitation,with some regions likely to have alternating episodes of intense flooding and mega-drought.Coastal areas will be exposed to more fre-quent saltwater inundation as sea levels rise.Local land managers desperately need intra-regional climate information for site-specific planning,management,and restoration activities.Managers will be chal-lenged to deliver freshwater to floodplains during climate change-induced drought,particularly within hydrologically altered and developed landscapes.Assessment of forest health,both by field and remote sensing techniques,will be essential to signal the need for hydrologic remediation.Studies of the util-ity of the release of freshwater to remediate stressed forested floodplains along the Murray and Mis-sissippi Rivers suggest that brief episodes of freshwater remediation for trees can have positive health benefits for these forests.The challenges of climate change in forests of the developing world will be considered using the Tonle Sap of Cambodia as an example.With little ecological knowledge of the im-pacts,managing climate change will add to environmental problems already faced in the developing world with new river engineering projects.These emerging approaches to remediate stressed trees will be of utmost importance for managing worldwide floodplain forests with predicted climate changes.

Climate and land-use change in wetlands:a dedication

Future climate and land-use change may wreak havoc on wetlands,with the potential to erode their values as harbors for biota and providers of human services.Wetlands are important to protect,particularly because these provide a variety of ecosystem services including wildlife habitat.

Broken connections of wetland cultural knowledge

As global agriculture intensifies,cultural knowledge of wetland utilization has eroded as natural resources become more stressed,and marginal farmers move away from the land.The excellent paper by Fawzi et al.(2016)documents a particularly poignant case of traditional knowledge loss among the Marsh Arab women of Iraq.Through interviews,the authors document the breakdown of skill transfer from the older to younger generation of women.The authors link the loss of their cultural knowledge with the loss of wetlands in the region.Women can no longer provide support for their families using wetland products,and along with that,their ancient knowledge of plant usage is lost.These ancient skills included medicinal uses,and reed harvesting for both weaving and water buffalo fodder.As,the majority of the Mesopotamian Marshes have dried,this way of life is being forgotten(Fawzi et al.2016).The global tragedy is that while the careful alliance of wetlands and people have sustained human cultures for millennia,degraded wetlands lose their ability to provide these services(Maltby 1986).