Gaining an understanding of landscape distributions of foliar traits is challenging due to interacting factors that influence ecosystems. These factors, including parent material, elevation, and local hillslope gradient, play a strong role in distributing water and nutrients across a landscape, which in turn can determine ecological patterning. Mt. Kinabalu, located in Malaysian Borneo, is a well-studied location in which to consider the relationships of these dynamics. This study area has two contrasting parent materials (sandstone and ultramafic), along an elevation gradient, where there is known variation in biogeochemical processes and nutrient limitation. However, our ability to consider foliar trait variation across these landscapes resulting from elevation changes, hillslope gradients, and different soil types, has traditionally been challenging to consider in concert due to the spatially intensive sampling required in often challenging terrain. Here we utilize integrated high-fidelity imaging spectroscopy (HiFIS) data from a Visible-Shortwave Imaging Spectrometer (VSWIR) and light detection and ranging (LiDAR) data from the Carnegie Airborne Observatory (CAO) to gain an understanding of the spatial variation and distributions of canopy traits and the underlying drivers of these patterns.
Results/Conclusions
We examined the foliar traits P, N, Ca, K, Mg (%), and leaf mass per area, mapped across the south and east faces of Mt. Kinabalu. using PLSR equations applied to HiFIS data (Martin et al., 2018). We found that while most foliar traits are significantly separated between parent materials at low elevation sites, this separation disappears with increasing elevation. However, even at low elevations there are not significant differences in Mg between forests on different substrates, likely due to characteristics of the ultramafic parent material. In addition, while rock derived nutrients have higher foliar concentrations at downslope positions in both parent materials at lower elevations, this pattern also diminishes for Ca and K at high elevation sites. In contrast, N and LMA do not vary along hillslopes in low elevation, low nutrient substrate locations. These results allow us to consider the drivers of these patterns across this matrix of conditions, including shifting climate and soil nutrient availability. The integration of VSWIR and LiDAR datasets allows us to incorporate local topographic conditions into this analysis for a more nuanced perspective on the interaction of these drivers in determining foliar trait distributions.