Water and nutrient cycling regulation functions in forest ecosystems: a comparison between native forests and exotic fast-growing tree species plantations in tropical highlands

Abstract

30An improved understanding of ecosystem functions is increasingly needed as ecosystem management moves towards 31 optimizing their capacity to provide services to society. Such a task requires the characterization of ecosystem functions in 32 strategic systems such as tropical mountain forests, which are also subject to pressure due to both global and local 33 environmental changes. In particular, transformation of native forests into pastures or agriculture, has been regarded as the 34 type of transformation with the largest effects in ecosystem regulating and provision functions. However, the effects of other 35 transformations such as those associated with replacement of native with planted forests, have been less studied. To evaluate 36 the effect of forest type on key-ecosystem functions related to water resources, we studied the dynamics of rainfall 37 partitioning and nutrient circulation on a suite of representative forest types in neotropical mountain systems: two plantations 38 of exotic fast-growing species and two types of native forests. Our results illustrate that, when considered in a per-basal unit 39 area, water transmission to the forest floor is significantly higher in both native forests. Similarly, native forests are more 40 effective on circulating nutrients on the ecosystem as they are better adapted to oligotrophic soils such as those occurring in 41 tropical mountains. These results suggest that the replacement of native forests with exotic tree plantations can potentially 42 impact hydrological regulation and the nutrient cycling in these high Andean lands, affecting both directly and indirectly the 43 capacity of ecosystems to produce services to society. 44 45

Orthophosphate fluxes in scattered trees from fragmented Andean landscapes highlight a biogeochemical role of foliar traits in pioneer species

“…Our results show differences in PO 4 ‐P circulation between tree species and among hydrological events, with higher average concentrations of PO 4 ‐P in Th and Sf than in Pi (Figures 3 and 6). In general, water is enriched with PO 4 ‐P when it comes into contact with the canopy, increasing the concentration of Phosphorous in water reaching the soil, as highlighted by previous studies from our group in natural forests in the Andes (León‐Peláez et al, 2020; Suescún et al, 2021). As expected, and similar to previous studies, Sf had the highest concentrations of PO 4 ‐P (Figures 3 and 6), potentially associated with more extended contact of water with the tree surfaces, as well as higher residence time (Wilcke et al, 2019).…”