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

Houcai Sheng,Tijiu Cai

doi:10.3390/f12040393

Abstract

Larix gmelinii forest is one of the dominant forest types in boreal forest and plays a unique eco-hydrological role in the terrestrial ecosystem. However, the throughfall variability in boreal forest ecosystems, which plays a crucial role in regulating hydrology, remains unclear. Here, we investigated the spatial variability and temporal stability of throughfall within a Larix gmelinii forest in the full leaf stage in Great Kingan Mountain, Northeast China, and the effects of rainfall properties and canopy structure on throughfall variability were systematically evaluated. The results indicate that throughfall represented 81.26% of the gross rainfall in the forest. The throughfall CV (coefficient of variation of throughfall) had a significant and negative correlation with the rainfall amount, rainfall intensity, rainfall duration, and distance from the nearest trunk, whereas it increased with increasing canopy thickness and LAI (leaf area index). The correlation analysis suggested that the throughfall variability was mainly affected by the rainfall amount (R2 = 0.7714) and canopy thickness (R2 = 0.7087). The temporal stability analysis indicated that the spatial distribution of the throughfall was temporally stable. Our findings will facilitate a better understanding of the spatiotemporal heterogeneity of throughfall and help the accurate assessment of throughfall and soil water within boreal forests.

Highlights

When rainfall passes through the forest canopy, it partitions into interception loss, throughfall, and stemflow [1]
We found that throughfall CV decreased with increasing distance from nearest trunk but increased with increasing canopy thickness and leaf area index (LAI)
Our findings suggest that different canopy traits influence the throughfall variability and that the index of canopy thickness may be a good choice for analyzing the canopy effect on throughfall (Figure 6b)

Summary

Introduction

When rainfall passes through the forest canopy, it partitions into interception loss, throughfall, and stemflow [1]. Interception loss and stemflow both occupy a smaller proportion, typically ranging from approximately 14.7 to 31.8% [2] and 0 to. Throughfall represents the largest proportion, and usually constitutes more than 70% of gross rainfall [4]. Throughfall can be subdivided into three parts—free throughfall, splash throughfall, and canopy drip, and the relative proportion of each part of throughfall in different forests is different [5]. Throughfall is a key input parameter in ecological, hydrological, and biogeochemical processes. In-depth understanding of the spatiotemporal patterns of throughfall is necessary for constructing hydrological models

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