The Water Storage Function of Litters and Soil in Five Typical Plantations in the Northern and Southern Mountains of Lanzhou, Northwest China

Abstract

Soil and water conservation is an important function of forest ecosystems; however, it remains unclear which forest type is best suited for water and soil conservation under the same site conditions. In order to clarify the soil and water conservation function of different plantations in the northern and southern mountains of Lanzhou city, we investigated several soil and water conservation function indicators (thickness and accumulation of litter, maximum water holding capacity and rate of litter, water holding capacity and water absorption rate of litter, soil infiltration rates, soil water content, soil bulk density, soil porosity, and soil water storage) of five plantation types (Platycladus orientalis plantations (Po), Robinia pseudoacacia plantations (Rp), Populus alba var. pyramidalis plantations (Pa), P. alba var. pyramidalis + R. pseudoacacia mixed plantations (Pa + Rp), and P. orientalis + R. pseudoacacia mixed plantations (Po + Rp)) and evaluated them using the gray correlation method. The results indicated the accumulation of litter varied from 13.50 to 47.01 t·hm−2 and increased in the order of Pa < Rp < Po < Po + Rp < Pa + Rp. The maximum water holding capacity of litter varied from 35.29 to 123.59 t·hm−2 and increased in the order of Pa < Rp < Po < Po + Rp < Pa + Rp. The soil physical properties (soil infiltration, porosity, and bulk density) of mixed plantations were better than those of pure plantations. The soil maximum water storage was significantly different among plantation types (p < 0.05), with an average varying from 3930.87 to 4307.45 t·hm−2, and was greater in mixed plantations than in pure plantations. Gray correlation analysis revealed that mixed plantations had the best conservation function of the five plantation types, followed by broad-leaved plantations and coniferous plantations. This suggests that the planting of mixed plantations dominated by Pa + Rp is therefore recommended in the future construction of plantations in the northern and southern mountains of Lanzhou to realize sustainable forest development.

Tree species composition affects litter eco‐hydrological function in Pinus massoniana conifer‐broadleaf mixed forest stands in southwest China

“…It is notable that the LWHC measured by indoor immersion only reflects ideal water‐holding conditions, which is likely higher than the LWHC under actual field conditions (Luara et al, 2022). Our results are consistent with those of previous studies showing that the LWHC of conifer‐broadleaf mixed forests is higher than that of coniferous forests (Bai et al, 2021; Jin et al, 2014; Su & Liu, 2022; Wang et al, 2007; Zhang et al, 2022). Furthermore, we speculate that the main litter in the undecomposed layer of the P. massoniana plantation primarily comprises needle‐leaf litter.…”

“…Litter characteristics, climatic factors, forest attributes and terrain factors were the dominant influencing factors (explaining 78% of the variation) on the water storage capacity of the forest ecosystem litter layers (Liu et al, 2023). The degree of litter decomposition is also an important factor affecting LWHC, and the higher the degree of litter decomposition, the higher the LWHC (Anna et al, 2015; Su & Liu, 2022; Zhang et al, 2022; Zhou et al, 2018). In line with previous studies, the LWHC of semi‐decomposed litter was significantly higher than that of undecomposed litter (Figure 3a), which may have resulted from a looser litter structure and an increasing number of voids due to decomposition, thus allowing a greater LWHC (Zhang et al, 2022).…”

“…Moreover, leaf morphological characteristics are important factors that can affect the water‐holding capacity and hydrological dynamics of the litter layer (Sato et al, 2004; Su & Liu, 2022; Zhou et al, 2018), such as the water‐holding capacity of broad‐leaved litter that can be greater than that of coniferous litter (Li, Kang, et al, 2021). Therefore, it is necessary to quantitatively study the water‐holding capacity of the litter layer in various typical forest types (particularly mixed forests) across different regions (Zhou et al, 2018).…”

“…Litter is formed by tree leaves, branches, flowers, fruits and animal dung (Da Silva et al, 2018; Luara et al, 2022) and is the surface cover layer of the hydrological function on the vertical structure of forest ecosystems, which plays a non‐negligible role in the forests hydrological function (Lv et al, 2020). The forest litter layer can intercept 10%–20% of natural precipitation, which reduces the infiltration rate of rainwater, thereby preventing runoff and erosion on the soil surface (Giácomo, 2017; Su & Liu, 2022). Therefore, the litter layer plays an important ecological role in forest soil formation and protection, material circulation, and energy flow (Da Silva et al, 2018; Qin et al, 2019; Uri et al, 2022).…”

“…Litter water‐holding characteristics (absorption rate and holding capacity) are important parameters for expressing litter water retention and storage capacity and are influenced by the forest type, litter composition, litter mass, litter thickness and the degree of litter decomposition (Alan & Alistair, 2018; Anna et al, 2015; Bharat et al, 2017; Jourgholami et al, 2022; Su & Liu, 2022). Compared with monoculture forests, mixed forests can significantly affect the composition, decomposition rate and the water‐holding capacity (Ilek et al, 2021).…”