Soil water repellency and pH soil change under tropical pine plantations compared with native tropical forest

SummaryIn temperate climates, soil water repellency (SWR) has been documented to develop with land-use change from native forest to pine plantations. In the tropics a sparse evidence base has been documented for the observation of SWR, but no investigation has been conducted to determine the consequences of changing land-use from native forest to pine plantations with regard to SWR. In our research we broaden the evidence base for tropical SWR by comparing the SWR behavior of seven tropical pine plantations in Trinidad with co-located native forest. We found that SWR occurred under both pine and native forest, but was more persistent and less heterogeneous under pine. The SWR was water content dependent with a threshold ∼0.2 m3 m−3, it showed a linear dependence with litter depth, and it was also found to be higher in more acidic soils. The forest floor pH, contrary to convention for temperate climates, was observed to increase under some pine plantations, as compared with native tropical forest. This only occurred in the very acidic tropical soils (pH < 4), but may have important biogeochemical consequences with regard to soil and water quality.

► Soil water repellency (SWR) exists in the tropics under both native forest and pine plantations.
► SWR was dependent on soil water content and on litter depth.
► We found maximum SWR in the interval 4 < pH > 4.5 and we did not find any SWR above pH 5.2.
► At pH < 4 we observed increases in soil pH under pine compared with native forest.