Tropical forests face significant disturbance from large-scale land-use changes, potentially impacting their overall ecosystem functioning. Phosphorus (P) is an essential nutrient with very low availability from the soil, constraining the productivity and functioning of tropical ecosystems. It is important to clarify the mechanisms underlying the effects of land-use change (particularly, monoculture conversion and restoration) on soil P cycling and to ensure sustainable land management in tropical regions.

In a study published in Agriculture, Ecosystems and Environment, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences and their collaborators analyzed the impacts of land use changes on plant community characteristics, soil P cycling dynamics, and soil physicochemical properties under different land use types. They also identified key predictors of available soil phosphorus.

By measuring such variables as soil organic carbon, microbial biomass phosphorus, fine roots, and acid phosphatase, the researchers analyzed the impact of tropical forest restoration on soil available P under different land uses (including monoculture plantations, farmland-regenerated secondary forests, rubber plantation-regenerated secondary forests, and primary rainforests). They used statistical methods to identify the main predictors of soil available P at different seasonal and annual time scales.

They found that the conversion of primary rainforests to monoculture plantations significantly reduced tree species diversity and modified soil P cycling (including total P, available P, microbial P and phosphatase activity). In contrast, farmland-regenerated secondary forests and rubber plantation-regenerated secondary forests significantly enhanced tree diversity and improved soil physicochemical conditions compared with monoculture plantations, thereby promoting soil P bioavailability by increasing soil organic C, microbial P and phosphatase activity.

Random forest model predictions indicated that soil organic carbon, microbial biomass phosphorus, and fine root biomass were the key factors predicting available soil phosphorus.

Moreover, fine roots of plants and leguminous tree species had a positive impact on soil phosphorus cycling, especially in the topsoil. Diverse communities with abundant leguminous species and well-developed root networks can effectively overcome P limitation and improve soil quality in the ecosystem.

Therefore, the study suggested that constructing communities rich in leguminous plants with diverse species and ensuring the input of organic matter will help maintain the sustainability of soil phosphorus resources in tropical regions.

Published: 31 December 2024