Comparisons of stemflow and its bio-/abiotic influential factors between two xerophytic shrub species

Abstract

Abstract. Stemflow transports nutrient-enriched precipitation to the rhizosphere and functions as an efficient terrestrial flux in water-stressed ecosystems. However, its ecological significance has generally been underestimated because it is relatively limited in amount, and the biotic mechanisms that affect it have not been thoroughly studied at the leaf scale. This study was conducted during the 2014 and 2015 rainy seasons at the northern Loess Plateau of China. We measured the branch stemflow volume (SF b ), shrub stemflow equivalent water depth (SF d ), stemflow percentage of incident precipitation (SF %), stemflow productivity (SFP), funnelling ratio (FR), the meteorological characteristics and the plant traits of branches and leaves of C. korshinskii and S. psammophila. This study evaluated stemflow efficiency for the first time with the combined results of SFP and FR, and sought to determine the inter-and intra-specific differences of stemflow yield and efficiency between the two species, as well as the specific bio-/abiotic mechanisms that affected stemflow. The results indicated that C. korshinskii had a greater stemflow yield and efficiency at all precipitation levels than that of S. psammophila. The largest inter-specific difference generally occurred at the 5-10 mm branches during rains of ≤ 2 mm. Precipitation amount was the most influential meteorological characteristic that affected stemflow yield and efficiency in these two endemic shrub species. Branch angle was the most influential plant trait on FR. For SF b , stem biomass and leaf biomass were the most influential plant traits for C. korshinskii and S. psammophila, respectively. For SFP of these two shrub species, leaf traits (the individual leaf area) and branch traits (branch size and biomass allocation pattern) had a great influence during lighter rains ≤ 10 mm and heavier rains > 15 mm, respectively. The lower precipitation threshold to start stemflow allowed C. korshinskii (0.9 mm vs. 2.1 mm for S. psammophila) to employ more rains to harvest water via stemflow. The beneficial leaf traits (e.g., leaf shape, arrangement, area, amount) might partly explain the greater stemflow production of C. korshinskii. Comparison of SF b between the foliated and manually defoliated shrubs during the 2015 rainy season indicated that the newly exposed branch surface at the defoliated period and the resulting rainfall intercepting effects might be an important mechanism affecting stemflow in the dormant season.

Rain concentration and sheltering effect of solar panels on cultivated plots

“…High Cv values indicate strong heterogeneities while values below 0.2 will be considered as acceptable, according to the standards of ASAE (1996) for irrigation uniformity. This threshold of 0.2 is also consistent with the reference values reported in Van der Gulik et al (2014).…”

“…For example, Diermanse (1999) showed that a correct simulation of runoff could often be achieved on the watershed scale from spatially averaged rainfall values, although clearly better results may be expected when explicitly accounting for the subscale spatial patterns of rain distribution (Faurès et al, 1995;Tang et al, 2007;Emmanuel et al, 2015). On the plot scale, rain interception and redistribution by the crops (Levia and Germer, 2015;Yuan et al, 2017) is already known to cause strong spatial heterogeneities (through stemflow, throughfall or improved water storage capabilities), thus raising multiple questions on soil microbiology, non-point source pollution and irrigation piloting (Lamm and Manges, 2000;Martello et al, 2015). The presence of solar panels will provide similar, additional issues close to those experienced in agroforestry when the vegetative cover is of various heights and nature, with a direct impact on the spatiotemporal patterns of rain redistribution (Jackson, 2000).…”

Hydrochemical Fluxes in Bulk Precipitation, Throughfall, and Stemflow in a Mixed Evergreen and Deciduous Broadleaved Forest

“…Due to variation in plant morphology, the initiation and rate of production for stemflow may differ significantly among tree species [41][42][43][44]. In addition, there are notable differences in the absorption ability and material composition of the different plant organs and epiphytic organisms [27].…”

A novel framework to study the effect of tree architectural traits on stemflow yield and its consequences for soil-water dynamics

“…Stemflow is formed in the forest canopy, and recent work has strived to unveil how canopy architecture can regulate the formation of stemflow before being funnelled belowground (e.g. Levia et al, 2010Bialkowski and Buttle, 2015;Yuan et al, 2017;del Campo et al, 2018). However, tree architecture is complex (e.g.…”