Leaf Functional Traits of Zanthoxylum planispinum ‘Dintanensis’ Plantations with Different Planting Combinations and Their Responses to Soil

Abstract

Leaf structural and physiological traits, nutrients, and other functional properties reflect the ability of plants to self-regulate and adapt to the environment. Species diversity can positively affect plant growth by improving the habitat, and offers mutual interspecies benefits. Therefore, optimizing the types of plants grown in a specific area is conducive to achieving sustainable development goals for plant growth. In this study, companion planting of Zanthoxylum planispinum ‘dintanensis’ (hereafter Z. planispinum) with Prunus salicina Lindl., Sophora tonkinensis Gagnep., Arachis hypogaea L. and Lonicera japonica Thunb. was investigated, along with a monoculture Z. planispinum plantation. The effect of different planting combinations on the adaptive mechanisms of Z. planispinum and its response to the soil was explored. These results revealed that Z. planispinum preferred the slow growth strategy of small specific leaf area, high leaf water content, and high chlorophyll content after combination with P. salicina. Conversely, after combination with S. tonkinensis, Z. planispinum exhibited a fast growth strategy. Combination with A. hypogaea enabled Z. planispinum to adopt a transition from slow to fast growth. Z. planispinum regulated its economy of growth through multiple functional trait combinations, indicating that planting combinations impacted its adaptive strategies. The adaptability of Z. planispinum in combination with P. salicina, L. japonica, A. hypogaea and S. tonkinensis decreased in turn, with only the adaptability of Z. planispinum + S. tonkinensis lower than that of the pure forest. Leaf functional traits were jointly influenced by soil water content, microbial biomass carbon (MBC), MB nitrogen (N), MB phosphorus (P), available N, total P and available calcium (C:N:P). The main contributors were soil water content, the different component levels and stoichiometry of elements and the MB. The results demonstrated that companion planting can promote or inhibit the growth of Z. planispinum by adjusting its functional traits.