Ecosystem services of high-altitude Afromontane palustrine wetlands in Lesotho

Although wetlands are among the most valuable ecosystems, the condition and extent of wetlands is declining worldwide, to the detriment of ecosystem service delivery. This study assessed the ecosystem services delivered by the Afromontane palustrine wetlands of Lesotho using the WET-EcoServices tool and explored the relationships of the services with environmental factors and plant functional traits using ordination techniques. Higher-altitude wetlands differed from the lower-altitude wetlands in the spectrum of services they deliver. These wetlands were mostly valued for carbon storage, provision of natural resources, streamflow regulation, maintenance of biodiversity and erosion control. Lower-altitude wetlands were valued for natural resources, cultivated foods, nitrate removal, phosphate trapping and streamflow regulation. The environmental factors affecting the delivery of ecosystem services most were altitude, longitude (directly correlated with rainfall in the context of Lesotho), landscape, soil parent material, slope and soil depth. The delivery of several services was also correlated with plant functional traits, for example, carbon storage and maintenance of biodiversity were positively correlated with plant shoot mass, total plant biomass and rooting depth. The location and environmental characteristics of a given wetland within a catchment and the functional characteristics of the wetland's dominant plant species have an influence on the ecosystem services that it delivers. However, the level of threat to ecosystem services is high, especially in the lower-altitude wetlands. The threats, which are mainly anthropogenic, are mostly associated with crop cultivation, overgrazing and trampling by livestock and economic development. Thus, for sustainable provision of wetland ecosystem services, these Afromontane palustrine wetlands require urgent attention and up-scaling of the conservation efforts.