Relationships between individual small tree canopy structure and rainfall interception

Among the layers of a plant community, the canopy has the most important hydrological function in water circulation. Understanding the canopy’s inner structure and its relationship to water transport is fundamental for the functional mechanisms of the vegetation canopy. Using an artificial rainfall simulator to supply three levels of rainfall intensity, the interception of rainfall by the canopy was measured to study the characteristics of individual trees using different rainfall conditions and structural parameters. The study was done for four small native tree species: Platycladus orientalis, Pinus tabulaeformis, Quercus variabilis and Acer elegantulum. The resulting variations in the process of canopy interception could be divided into periods of increasing, slightly decreasing in some species, and stable levels of interception. In addition, duration of the initial period of increasing interception shortened as rainfall intensity increased. When rainfall was less intense, the percentage of gross rainfall intercepted by P. orientalis, P. tabulaeformis and A. elegantulum canopy layers was in the order mid > upper > lower canopy, while for Q. variabilis the sequence was upper > mid > lower canopy. These sequences indicate that canopy superstructure was more important than canopy substructure regarding the ability of the canopy to intercept precipitation and thus prevent soil erosion. Furthermore, it was found that exponential and logarithmic functions could be used to describe the relationship between interception of coniferous and deciduous species, respectively, and their own canopy body types. This study provided preliminary criteria for determining the optimal crown type for rainfall interception.