The effects of stemflow on redistributing precipitation and infiltration around shrubs

Abstract

Abstract:The experiments of stemflow of two semiarid shrubs (Caragana korshinskii and Hippophae rhamnoides) and its effect on soil water enhancement were conducted from 1 st May to 30 th September of 2009-2013 in the Chinese Loess Plateau. Stemflow values in C. korshinskii and H. rhamnoides averaged 6.7% and 2.4% of total rainfall. The rainfall threshold for stemflow generation was 0.5 and 2.5 mm for C. korshinskii and H. rhamnoides. When rainfall was less than 17.0 mm, the funnelling ratios were highly variable, however, stable funnelling ratios were found for rainfall greater than 17.0 mm for C. korshinskii. The funnelling ratios of H. rhamnoides first increased until a threshold value of 10.0 mm and then the funnelling ratios begin stabilize. The wetting front depths in the area around stem was 1.4-6.7 and 1.3-2.9 times deeper than area outside the canopy for C. korshinskii and H. rhamnoides. Soil moisture at soil depth 0-200 cm was 25.6% and 23.4% higher in soil around stem than that outside canopy for C. korshinskii and H. rhamnoides. The wetting front advanced to depths of 120 and 100 cm in the area around stem and to depths of 50 cm in the area outside the canopy for C. korshinskii and H. rhamnoides suggested that more rain water can be conserved into the deep soil layers through shrub stemflow. Soil moisture was enhanced in the area outside the shrub canopy, only when rainfall depth is > 4.7 and 5.1 mm, which is an effective rainfall for the area for C. korshinskii and H. rhamnoides. While for the area around stem of C. korshinskii and H. rhamnoides, the corresponding threshold values are 3.2 and 4.3 mm. These results confirmed that stemflow has a positive effect on soil moisture balance of the root zone and the enhancement in soil moisture of deeper soil layers.

The Effect of Soil Preparation Methods on Rain Water Infiltration as The Basis of Irrigation Application for Dry Land Rice

“…This is because the soil is getting saturated, thereby reducing its ability to absorb water. Jian et al (2018) also showed a similar pattern of logarithmic relationship (function) between the depth of infiltration and the amount of rain in the soil around shrub with an R 2 value 0.77 and 0.89 in positions around the shrub stems and an R 2 of 0.81 in the soil outside the shrub. From Figure 4 we can observe that in tillage with hoeing plus loosening (T2), a volume of 350 L of rain (equivalent to a rain thickness of 9.7 mm) can produce water infiltration up to a rooting depth of 20 cm.…”

“…A very close relationship between rainfall duration and infiltration depth is shown by the high R2 value of all land preparation methods (R2 = 95% to 99%). Jian et al (2018) also found a positive relationship between the depth of infiltration and the amount of rain in the form of a logarithmic function.…”

Defining minimum runoff length allows for discriminating biocrusts and rainfall events

“…First, there is a larger number of plant roots acting as preferential infiltration routes; second, fine-grained plant patches are more efficient in reducing runoff than the coarse-grained ones (Bautista et al, 2007). In addition, soil porosity is larger under plants (Mora and Lázaro, 2014), and plants further increase infiltration by intercepting rainfall and producing stemflow (Jian et al, 2018). Furthermore, under alpha grass, biocrust rarely develops (Eldridge et al, 2010), but under plants such as Euzomodendron bourgaeanum, Helianthemum almeriense or Salsola genistoides, which are in the Lepra plots, biocrust (which favours runoff) is much more frequent than the 20% of cases that Kidron (2015) found under the canopy at Nizana (Israel).…”

Spatial variation of grassland canopy affects soil wetting patterns and preferential flow

“…Especially dry soils can cause water repellence or lead to shrinking, thus enhancing preferential flow (Beven & Germann, 2013; Jarvis, 2007; Nimmo, 2021). Compared to the spatial variation of net precipitation, research on the role of canopy processes on soil hydrology is much rarer and has mostly been performed in forests and shrublands (e.g., Bouten et al, 1992; Jian et al, 2018; Li et al, 2009; Metzger et al, 2017; Molina et al, 2019), while small structured vegetation communities are underrepresented (Dunkerley, 2000; Llorens & Domingo, 2007; Sadeghi et al, 2020). In forest ecosystems, it was investigated partly by using model‐based approaches and field observations on how canopy‐modified net precipitation patterns influence soil water content or soil water fluxes (Coenders‐Gerrits et al, 2013; Guswa, 2012; Klos et al, 2014; Metzger et al, 2017).…”