Annual litterfall dynamics and nutrient deposition depending on elevation and land use at Mt. Kilimanjaro

[摘要] Litterfall is one of the major pathways connecting above- and below-groundprocesses. The effects of climate and land-use change on carbon (C) andnutrient inputs by litterfall are poorly known. We quantified and analyzedannual patterns of C and nutrient deposition via litterfall in naturalforests and agroforestry systems along the unique elevation gradient of Mt.Kilimanjaro.

Tree litter in three natural (lower montane, Ocotea and Podocarpus forests),two sustainably used (homegardens) and one intensively managed (shadedcoffee plantation) ecosystems was collected on a biweekly basis from May2012 to July 2013. Leaves, branches and remaining residues were separatedand analyzed for C and nutrient contents.

The annual pattern of litterfall was closely related to rainfallseasonality, exhibiting a large peak towards the end of the dry season(August–October). This peak decreased at higher elevations withdecreasing rainfall seasonality. Macronutrients (N, P, K) in leaf litterincreased at mid elevation (2100 m a.s.l.) and with land-use intensity.Carbon content and micronutrients (Al, Fe, Mn, Na) however, were unaffectedor decreased with land-use intensity.

While leaf litterfall decreased with elevation, total annual input wasindependent of climate. Compared to natural forests, the nutrient cycles inagroforestry ecosystems were accelerated by fertilization and the associatedchanges in dominant tree species.

[学科分类] 地球化学与岩石