Great Basin Naturalist


Throughfall and stemflow are important components of hydrologic processes in forests, but relative contributions of multiple factors, including precipitation volume, plant size, and folivory (leaf removal by defoliators), on throughfall/stemflow have not been reported. This paper reports the relative influences of precipitation volume (0–230 L m−2), sapling size (1.4–6.7 cm diameter at root collar; 0.07–0.45 kg calculated dry foliage mass), and manipulated folivory (0–20% foliage removal) on throughfall volume and N, K, and Ca fluxes as evaluated with stepwise multiple regression in a young Douglass-fir (Pseudotsuga menziesii [Mirb.] Franco) ecosystem.

Precipitation volume explained most variation in throughfall volume (R2 = 0.81). Folivory and sapling size each had significant but minor effects on throughfall volume and nutrient fluxes. These data indicate that folivore effects, while significant, are masked by precipitation in this wet ecosystem. Wider ranges in sapling size and folivory and/or drier conditions likely would improve interpretation of their influence on throughfall volume and chemistry.