Multifactor relationships between stand structure and soil and water conservation functions of Robinia pseudoacacia L. in the Loess Region

Abstract

Ninety-six sample plots were established for a tree census to explore the multifactor relationships between the soil and water conservation functions and the stand structure in a typical black locust ( Robinia pseudoacacia L.) plantation in the Caijiachuan watershed of the Loess Plateau, Western Shanxi Province, China. Based on the observational and experimental data, a topography-structure-function model was built using a structural equation modeling (SEM) approach. The latent variables were the topographical factors, horizontal structure, vertical structure, soil and water conservation, and sediment reduction. The results indicated that the horizontal structure of the Robinia pseudoacacia L. forest was the most obvious latent variable, which was expressed in the path coefficient (pc = 0.85) corresponding to the sediment reduction; the stand density and tree competition index were the major drivers of the structure, with path coefficients of −0.96 and −0.92 and influence coefficients of −0.997 and −0.998. These factors are easily regulated. Among these factors the stand density of the arbor layer is recommended to be kept stable within the range from 1600 to 1700 trees/hm 2 . These relationships showed that reducing the tree competition index and changing the microtopography could effectively enhance the soil and water conservation functions in this ecologically significant loess area.

Multifactor relationships between the forest structure and water conservation function of Picea crassifolia Kom. plantations in Qinghai Province, China

“…Our finding that the tree growth rate and water conservation function were significantly decreased as competition increased (Table 4 and Figure 3) is consistent with the results of most studies (Contreras et al, 2011; de Andres et al, 2018; Wei & Liang, 2019). Competition for resources between trees primarily consists of aboveground competition for light and belowground competition for nutrients and water; aboveground competition is generally thought to be size‐asymmetric because large trees can obtain disproportionately large amounts of light by shading and thus suppress the growth of surrounding trees (Craine & Dybzinski, 2013).…”

“…We found positive effects of an uneven distribution on water conservation function (Figure 3 and Figure 4), which is in line with the results of Wei and Liang (2019). This is presumably because of the forest gaps caused by the less uniform distribution of trees.…”

Biotic Factors Drive Woody Plant Species Diversity across a Relative Density Gradient of Quercus aliena var. acuteserrata Maxim. in the Warm–Temperate Natural Oak Forest, Central China

“…Forest community dynamics depend on stochastic processes in which temporal changes in community composition are affected by biotic and abiotic factors over time [4]. Biotic factors comprises numerous quantifiable biometric characteristics, such as stand structure, competition interaction, and so on [5,6]. Stand structure refers to the spatial arrangement and attributes of the various components of the ecosystem, such as individual tree size variation among and within species, the size and height of the canopy, and the spacing of trees [7].…”

Seed Germination and Seedling Growth of Robinia pseudoacacia Depending on the Origin of Different Geographic Provenances

“…In Romania, the area occupied by black locust has increased continuously [25,26]. Depending on the favorable ecological conditions, black locust could contribute in the same way as other forest species or by supplementing them, ensuring the multiple functions of the forest at local, zonal, regional, national or global levels [27][28][29][30][31][32][33][34]. The quality of the seeds is the first condition for the afforestation to be successful and for the resulting forests to fulfil their numerous functions; i.e., production, protection, ecological, cultural, educational, etc.…”

“…Black locust seeds require pre-treatment before sowing in order to break exogenous dormancy, due to the structure of the seed coat, which is impermeable to water and gases [38]. Moreover, the imbibition and course of processes that are essential for germination are inhibited in the dormancy stage [33,43]. The impermeability of the seed coat, understood as physical dormancy, is a very important ecological mechanism for species to ensure that germination occurs only in favorable conditions for seedling growth [44,45].…”