Analysis of the dynamics of land use gradient intensity on carbon flux, surface energy balance, and water use efficiency in Southeast Asian forest and plantation systems
Land use and land cover change significantly transform the ecosystem services. Southeast Asia is the most affected region by land use and land cover change. In past decades, plantations are slowly dominating the landscape across this region. Those changes impacted vegetation composition from forests into monoculture and increased land use intensity. Furthermore, land use intensity usage altered land and atmospheric interactions. Comprehensive syntheses on the impact of different land use intensities on carbon, energy, and water fluxes are required to develop a robust mitigation and adaptation program for climate change.
Therefore, this study investigated the impact of different land use gradient intensities on carbon, energy, and water fluxes. This study compiled 10 sites of eddy covariance data covering forest and plantation systems across Southeast Asian region. Land use intensity is categorized as low (forests), medium (secondary forests), and high (plantations). This study investigated carbon flux components (net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (Reco)), surface energy balance (net radiation (Rn), latent heat (LE), sensible heat (H), light use efficiency (LUE), Bowen ratio), water fluxes (water use efficiency (WUE), relative extractable water (REW), soil water content (SWC)) and SPEI drought index on each land use intensity.
Based on the analysis, depending on the vegetation types, land use with high-use intensity were greater carbon sinks compared to forests and secondary forests. However, it promotes water stress and prolonged drought periods. This finding suggests the tradeoff between carbon and water in high-intensity land use. Plantations, in a limited period, produced high gross primary productivity, but on a longer time scale, it threatened the water availability in the landscape. There is no significant difference in ecosystem response to energy fluxes between land use intensity gradients. Furthermore, forests demonstrated better water use efficiency than secondary forests and plantations. Forests ensured ecosystem resilience to water stress, but plantations demonstrated high carbon accumulation. These results provide useful information for improving ecosystem model simulations, which incorporate complex land-use systems.