Rainfall partitioning varies across a forest age chronosequence in the southernAppalachianMountains

Abstract

Evaporation of precipitation from plant surfaces, or interception, is a major component of the global water budget. Interception has been measured and/or modelled across a wide variety of forest types; however, most studies have focused on mature, second-growth forests, and few studies have examined interception processes across forest age classes. We present data on two components of interception, total canopy interception (E i ) and litter interception-that is, O i + O e horizon layers-(E ff ), across a forest age chronosequence, from 2 years since harvest to old growth. We used precipitation, throughfall, and stemflow collectors to measure total rainfall (P) and estimate E i ; and collected litter biomass and modelled litter wetting and drying to estimate evaporative loss from litter. Canopy E i , P minus throughfall, increased rapidly with forest age and then levelled off to a maximum of 21% of P in an old-growth site.Stemflow also varied across stands, with the highest stemflow (~8% of P) observed in a 12-year-old stand with high stem density. Modelled E ff was 4-6% of P and did not vary across sites. Total stand-level interception losses (E i + E ff ) were best predicted by stand age (R 2 = 0.77) rather than structural parameters such as basal area (R 2 = 0.49) or leaf area (R 2 < 0.01). Forest age appears to be an important driver of interception losses from forested mountain watersheds even when stand-level structural variables are similar. These results will contribute to our understanding of water budgets across the broader matrix of forest ages that characterize the modern forest landscape.

Rainfall Partitioning in Chinese Pine (Pinus tabuliformis Carr.) Stands at Three Different Ages

“…We found that throughfall decreased while the canopy interception increased with increasing age, this pattern was in accordance with conifer species rainfall partitioning trend from young to adult in temperate boreal forests [13] and with deciduous forest A. altissima [31]. The study on a series of succession stands of Liriodendron tulipifera forest in the southern Appalachian Mountains also found that canopy interception increased rapidly with the forest age until reaching a maximum of 21% [27]. Another study on different Chinese fir stand ages got the similar trend that interception ratio in mature stands significantly higher [29].…”

Drought sensitivity of an N2‐fixing tree may slow temperate deciduous forest recovery from disturbance

“…Almost all precipitation ends up as throughfall in these young forests, as canopy interception is low (Brantley et al 2019). In the final year, some larger trees grew above the treatment panels, but changes to the treatment effect should have been minimal, because canopy interception for trees of this age is low (Brantley et al 2019). The 2013 growing season had 26% higher precipitation than the long-term average, while 2014 and 2015 were near average (7% and 0% higher, respectively; Miniat et al 2017).…”

“…Almost all precipitation ends up as throughfall in these young forests, as canopy interception is low (Brantley et al 2019). Almost all precipitation ends up as throughfall in these young forests, as canopy interception is low (Brantley et al 2019).…”

“…In July of 2013, we installed panels that removed either 0%, 20%, or 40% of incoming throughfall incident on the forest floor, to augment the natural level of soil moisture variability in our study site (Appendix S2). Almost all precipitation ends up as throughfall in these young forests, as canopy interception is low (Brantley et al 2019). Panels remained in place during the 2013, 2014, and 2015 growing seasons (mid-May to mid-October), and were removed each winter.…”

“…Stand age was 3 yr at the start of the treatment period and 5 yr at the end of the experiment, which corresponded to mean tree heights in our plots of 0.32 m and 1.30 m, respectively. In the final year, some larger trees grew above the treatment panels, but changes to the treatment effect should have been minimal, because canopy interception for trees of this age is low (Brantley et al 2019). Soil moisture was estimated every 15 min across 0-15-cm mineral soil depth at the center of each plot, and hourly means were logged (CS-655, CR1000 Campbell Scientific, Logan, Utah) for the duration of the study.…”