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

Chuan Yuan, Guangyao Gao, Bojie Fu
2017 Hydrology and Earth System Sciences  
<p class="p"><strong>Abstract.</strong> 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.
more » ... s Plateau of China. We measured the branch stemflow volume (SF<sub>b</sub>), shrub stemflow equivalent water depth (SF<sub>d</sub>), stemflow percentage of incident precipitation (SF<span class="thinspace"></span>%), stemflow productivity (SFP), funnelling ratio (FR), the meteorological characteristics and the plant traits of branches and leaves of <i>C. korshinskii</i> and <i>S. psammophila</i>. 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 <i>C. korshinskii</i> had a greater stemflow yield and efficiency at all precipitation levels than that of <i>S. psammophila</i>. The largest inter-specific difference generally occurred at the 5&amp;ndash;10<span class="thinspace"></span>mm branches during rains of ≤ <span class="thinspace"></span>2<span class="thinspace"></span>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<sub>b</sub>, stem biomass and leaf biomass were the most influential plant traits for <i>C. korshinskii</i> and <i>S. psammophila</i>, 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<span class="thinspace"></span> ≤ <span class="thinspace"></span>10<span class="thinspace"></span>mm and heavier rains<span class="thinspace"></span> &amp;gt; <span class="thinspace"></span>15<span class="thinspace"></span>mm, respectively. The lower precipitation threshold to start stemflow allowed <i>C. korshinskii</i> (0.9<span class="thinspace"></span>mm vs. 2.1<span class="thinspace"></span>mm for <i>S. psammophila</i>) 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 <i>C. korshinskii</i>. Comparison of SF<sub>b</sub> 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.
doi:10.5194/hess-21-1421-2017 fatcat:52lw2wingrdlrkonkrjeaj6kry