Why does oriental arborvitae grow better when mixed with black locust: Insight on nutrient cycling?

Abstract

To identify why tree growth differs by afforestation type is a matter of prime concern in forestry. A study was conducted to determine why oriental arborvitae (Platycladus orientalis) grows better in the presence of black locust (Robinia pseudoacacia) than in monoculture. Different types of stands (i.e., monocultures and mixture of black locust and oriental arborvitae, and native grassland as a control) were selected in the Loess Plateau, China. The height and diameter at breast height of each tree species were measured, and soil, shoot, and root samples were sampled. The arbuscular mycorrhizal (AM) attributes, shoot and root nutrient status, height and diameter of black locust were not influenced by the presence of oriental arborvitae. For oriental arborvitae, however, growing in mixture increased height and diameter and reduced shoot Mn, Ca, and Mg contents, AM fungal spore density, and colonization rate. Major changes in soil properties also occurred, primarily in soil water, NO 3‐N, and available K levels and in soil enzyme activity. The increase in soil water, N, and K availability in the presence of black locust stimulated oriental arborvitae growth, and black locust in the mixed stand seems to suppress the development of AM symbiosis in oriental arborvitae roots, especially the production of AM fungal spores and vesicles, through improving soil water and N levels, thus freeing up carbon to fuel plant growth. Overall, the presence of black locust favored oriental arborvitae growth directly by improving soil water and fertility and indirectly by repressing AM symbiosis in oriental arborvitae roots.

Plant–plant interactions affect seasonal nitrogen uptake of subalpine conifer seedlings by altering root traits and soil nitrogen availabilities

“…Zhou et al (2021) found that biomass for Cunninghamia lanceolata was promoted via increased soil nutrient availabilities by neighbouring conifer species (Pinus massoniana). In our study, higher NR activity under interspecific planting than intraspecific planting (Table 2) could contribute to the growth of A. faxoniana, considering that resource activation plays an essential role in interspecific interactions (Rachid et al, 2013;Chen et al, 2018).…”

Inter-Species Root Interaction Can Shift Feedback Effect of Arbuscular Mycorrhizal Fungi from Neutral to Positive or Negative

“…These mixed stands of P. orientalis and R. pseudiacacia create microclimates and soil conditions helping their growth (Zhai et al, 1991). This mixed-stand afforestation strategy has remodeled the community of rhizosphere-inhabiting AM fungi on the Loess Plateatu according to our previous study (Chen et al, 2018a, Chen et al, 2018b. The AM fungal community in native grasslands strongly differed from those in afforested zones (Fig.…”

Different transpiration and growth patterns of the black locust plantation and natural oak forest on China's Loess Plateau

“…Zhang et al (2020) found that the annual percentage loss of whole‐plant hydraulic conductance in black locust forests linearly increased with a reduction in MAP, exceeding 60% at MAP <446 mm, which suggests a severe restriction in sustainable growth. In site with long‐term soil water deficit, the communities tended to degrade and were gradually replaced to other communities (Chen et al, 2018; Wu et al, 2011). Although black locust plantations were successfully introduced into wet areas or regions with accessible groundwater, factors such as stand age, recovery stage and stand density should be considered to formulate appropriate management measures in regions with insufficient precipitation.…”