Temporal persistence of throughfall heterogeneity below and between the canopies of juvenile lodgepole pine (Pinus contorta)

Abstract

Abstract:From May to October 2010, throughfall associated with 38 rainfall events in three below-canopy zones (inner canopy, midcanopy and canopy periphery) of nine juvenile lodgepole pine trees and in open areas between canopies was measured along north, south, east and west transects radiating from each tree bole. Median cumulative throughfall (%) significantly differed among the canopy zones under differing rain depth classes and was negatively correlated with tree size metrics, but only for certain combinations of canopy zones and rain depth classes. Although median cumulative throughfall (%) was negatively correlated with canopy cover fraction when all below-canopy gauges were considered, this relationship only held true for the inner-canopy and mid-canopy zones under relatively small rain depth classes. Additionally, cumulative throughfall (%) was often dependent on transect direction, with event throughfall showing a dependence on the direction of storm origin. Throughfall coefficient of variation (%) also varied by zone and was a function of not only rainfall depth but also other storm variables such as the maximum 30-min rainfall intensity and the number and duration of intra-storm breaks. Temporal persistence of throughfall was assessed using time stability plots and Spearman rank coefficients of rain event and depth class pairings for all gauges and by canopy zone, and the influence of temporal lag and meteorological variables on persistence was assessed. The implications of our findings on throughfall sampling and for future ecohydrological studies in juvenile lodgepole pine and similar stands are discussed.

Spatial Variability and Temporal Persistence of Event Runoff Coefficients for Cropland Hillslopes

“…When simulating catchment runoff responses across events, is there any relationship between the spatial patterns of runoff coefficient at different times that may need to be considered? This question is inspired by (1) the discoveries of temporal stability of spatial pattern in soil moisture (e.g., Cosh et al, ; Vachaud et al, ; Vanderlinden et al, ; Zhang et al, ), precipitation (e.g., Carlyle‐Moses & Lishman, ; Keim et al, ), and infiltration (Jaynes & Hunsaker, ); and (2) the notion that hydrologic systems are not necessarily completely random, but most of the times show organization or pattern to some degree (Dooge, ). It appears that while event‐scale runoff coefficient is highly variable across neighboring hillslopes, its spatial pattern is often temporally stable (Figures , , and ).…”

“…Precipitation (e.g., Carlyle‐Moses & Lishman, ; Keim et al, ), soil moisture (e.g., Vachaud et al, ; Wang et al, ; Western & Grayson, ), infiltration (e.g., Smith & Hebbert, ), river network (e.g., Rinaldo et al, ), land use and others, each is related with large‐ or small‐scale spatial patterns. Together they produce the runoff variability across spatiotemporal scales.…”

Rainfall partitioning through a mixed cedar swamp and associated C and N fluxes in Southern Ontario, Canada

“…Vegetated canopies significantly alter the delivery of atmospheric water to the ground surface, reducing the total flux of incident precipitation and increasing the spatial variability of impact and the form of delivery. The redistribution of rain to the ground as it passes through a vegetated canopy is dependent on both the stand dynamics (Carlyle‐Moses & Lishman, ) and the precipitation‐event dynamics (Siegert, Levia, Leathers, Van Stan, & Mitchell, ). This rainfall partitioning has the capacity to affect ecosystem processes by creating hotspots of increased soil moisture and infiltration (Carlyle‐Moses, ; Cayuela, Llorens, Sánchez‐Costa, Levia, & Latron, ; Spencer & van Meerveld, ).…”

Spatial Variability of Throughfall in a Larch (Larix gmelinii) Forest in Great Kingan Mountain, Northeastern China

“…However, differences in plot size, stand density, tree species, leaf phenology, and even leaf shapes can lead to throughfall spatial heterogeneity [9,[22][23][24], which makes it difficult to obtain representation of throughfall measurements. Although the spatial variability of throughfall has been studied in tropical and temperate forests [10], the relationship between throughfall spatial variability and its influencing factors remains unclear [25].…”

“…Nevertheless, previous research mostly focused on the impact of climate change, permafrost thaw, and forest recovery on water yield [27,28] and forest canopy interception loss [29], while ignoring the impact of the complexity of forest cover on hydrological processes. According to studies conducted in different forest types, throughfall is a key transfer mechanism in the biogeochemical cycles [25]. Therefore, a better understanding of distribution patterns of throughfall in a larch forest is a precondition to give full play to the water conservation function of boreal forest.…”