Spatial Distribution of Tree Species Governs the Spatio-Temporal Interaction of Leaf Area Index and Soil Moisture across a Forested Landscape

Abstract

Quantifying coupled spatio-temporal dynamics of phenology and hydrology and understanding underlying processes is a fundamental challenge in ecohydrology. While variation in phenology and factors influencing it have attracted the attention of ecologists for a long time, the influence of biodiversity on coupled dynamics of phenology and hydrology across a landscape is largely untested. We measured leaf area index (L) and volumetric soil water content (θ) on a co-located spatial grid to characterize forest phenology and hydrology across a forested catchment in central Pennsylvania during 2010. We used hierarchical Bayesian modeling to quantify spatio-temporal patterns of L and θ. Our results suggest that the spatial distribution of tree species across the landscape created unique spatio-temporal patterns of L, which created patterns of water demand reflected in variable soil moisture across space and time. We found a lag of about 11 days between increase in L and decline in θ. Vegetation and soil moisture become increasingly homogenized and coupled from leaf-onset to maturity but heterogeneous and uncoupled from leaf maturity to senescence. Our results provide insight into spatio-temporal coupling between biodiversity and soil hydrology that is useful to enhance ecohydrological modeling in humid temperate forests.

A method to downscale soil moisture to fine resolutions using topographic, vegetation, and soil data

“…Similarly, Naithani et al (2013) found that soil moisture and vegetation patterns are very similar from leaf-onset to maturity but different from leaf maturity to senescence. Overall, the factors influencing soil moisture are related to the presence or absence of vegetation (Gómez-Plaza et al, 2001).…”

Environmental and physiological controls on sap flow in a subhumid mountainous catchment in North China

“…The leaf surface is the site of water vapor exchange, and therefore, leaf area, which can be reflected by LAI, controls tree transpiration (Kikuzawa, 1995;Naithani et al, 2013;Sellers et al, 1997). We did not perform an in situ measurement of LAI; a Moderate Resolution Imaging Spectroradiometer (MODIS) LAI product (MCD15A3) was adopted as the observation value.…”

Quantifying an early signature of the industrial revolution from lead concentrations and isotopes in soils of Pennsylvania, USA

“…1). The catchment is largely vegetated by deciduous trees (maple, oak, and beech) as well as hemlock and pine (Lin, 2006;Naithani et al, 2013). The catchment experienced two significant perturbations in the geologically recent past: a perturbation from peri-glacial to modern conditions ($15 kyr; Gardner et al, 1991) that has affected long-term regolith formation processes (Ma et al, 2010, and clearing of forests during colonial occupation that represents a short-term disturbance to local ecology and the environment.…”