Spatial Patterns and Temporal Stability of Throughfall in a Mature Douglas-fir Forest

Forest plays a key role in spatial distribution of rainfall and nutrients at fine spatial scales. Areas of localized rainfall and nutrient input at the soil surface may have a large effect on several hydrological and biogeochemical processes. In this paper, a Douglas-fir stand was revisited to evaluate the changes in the throughfall spatial distribution and its temporal stability due to forest growth and thinning. We used 32 funnel-type collectors distributed in a random stratified array within a 0.2 ha plot to measure throughfall amounts from February to November 2015. The throughfall variability was much lower as compared to the values reported ~25 years ago in the same site. We further assessed the spatial patterns of throughfall in spring and summer. We detected a spatial correlation length of 12 m and 8 m for spring and summer, respectively, which are higher than the values reported for other mature Douglas-fir forests in similar climatic conditions. Temporal stability plots confirmed that detected spatial patterns were stable in time.