Karst Soil Patch Heterogeneity with Gravels Promotes Plant Root Development and Nutrient Utilization Associated with Arbuscular Mycorrhizal Fungi

Abstract

Arbuscular mycorrhizal (AM) fungi associated with plant roots play an essential role in the belowground ecological process in karst habitats with high spatial and substrate heterogeneity. However, the effects of AM fungi on root morphology and nutrient uptake under different soil patch sizes and gravel content in karst habitats are still unclear. A controlled experiment was conducted using a square device divided into 16 grid patches. This experiment had three treatments, including the mycorrhizal fungal treatment inoculated with (M+) or without Glomus etunicatum Becker & Gerd (M−), the patch heterogeneity treatment through the homogeneous patch (Homo), heterogeneity-large patch (Hetl) and heterogeneity-small patch (Hets), and substrate heterogeneity treatment through the gravel-free substrate (GF), gravel-low substrate (GL), and gravel-high substrate (GH). Root traits and nutrients of Bidens pilosa L were analyzed, and the result showed the AM fungi significantly increased the dry weight, length, surface area, average diameter, volume, tips, branching points, and N, P, and K acquisitions of B. pilosa roots, but significantly decreased the specific root length. The Hets with soil and gravel increased the dry weight, length, surface area, tips, branching points, and N, P, and K acquisitions of B. pilosa roots compared with Hetl regulated by AM fungi. The GL and GH treatments also increased the dry weight, length, surface area, tips, branching points, and N, P, and K acquisitions of B. pilosa roots compared with GF regulated by AM fungi. These results indicate that the B. pilosa roots’ nutritional acquisition benefits were higher in Hets mixed with gravel for its root morphological development regulated by AM fungi in karst soil. In conclusion, we suggest that soil patch heterogeneity with gravels promotes root morphological development and nutrient utilization to karst plants associated with arbuscular mycorrhizal fungi.

Effects of AMF on plant nutrition and growth depend on substrate gravel content and patchiness in the karst species Bidens pilosa L

“…Bidens pilosa L. is an annual herb of the Asteraceae and is widely distributed in the karst areas of southwest China ( Li et al., 2021 ). B. pilosa is the typical pioneer succession species of karst vegetation documented by our field surveys, and our previous found that it has a high rate of mycorrhizal colonization ( He et al., 2019 ; Han et al., 2020 ; Li et al., 2022 ; Sun et al., 2022 ). Therefore, B. pilosa was selected as the plant material in this study.…”

Recent Advances in Plant: Arbuscular Mycorrhizal Fungi Associations and Their Application to Cassava Crops

“…Several investigations into the mechanism of action of nutrient absorption and translocation with AMF have found that: i. The mycorrhizal hyphae can stretch and explore a larger region of the ground soil than the roots of the host plant can achieve, thereby enabling it to gain access to both micro and macronutrients that the plant alone is unable to absorb [17]. Hence, AMF can cross the depletion zone caused by the plant's quick uptake of nutrients in the region around its root system and provide the appropriate nutrient elements to the plant [12].…”

Strategy Trade-Off of Predominant Stress Tolerance Relative to Competition and Reproduction Associated with Plant Functional Traits under Karst Forests

“…According to the CSR theory of Grime (1977), the S strategy plants are mainly for survival by stress-tolerance in harsh habitat conditions, and the C strategy plants are mainly for conquest through competition due to scarce resources, while the R strategy plants are mainly for reproduction through increasing individuals of a population [2]. In particular, the karst maintains a lower resource of N and P and a barren soil layer with higher heterogeneous habitat [4,57,58], leading to adverse habitat conditions and scarce habitat resources. Therefore, competing for limited N and P resources through stress tolerance for individual survival is necessary as the optimal strategy of S with C in adverse karst habitats to maintain fewer family members.…”

“…Specifically, strategy C is mainly to improve the competitive ability, strategy S is mainly to grow maintenance under limited resource conditions, and strategy R is mainly to cycle fast for life reproduction in suffering frequent interference [2,3]. CSR theory can not only be adopted to explain the ecological process of community integration, biodiversity maintenance, and vegetation succession [4][5][6], but also the ecosystem function productivity and community stability [7,8]. Plant survival Forests 2023, 14, 1258 2 of 14 could be reflected by ecological strategies via plant functional traits responding to environmental changes [9,10].…”

“…Landscape fragmentation of karst leads to different microhabitats, such as stone caverns, grooves, surfaces, and soil surfaces [32]. These microhabitats are interlaced distribution each other, resulting in a highly heterogeneous habitat [33,34], due to high rock exposure rate, discontinuous soil cover, and poor water retention led to infertile soil such as N or P [4,35]. Further, these heterogeneous habitats affect plant composition and diversity, also regulating plant functional traits at individual and community levels [36,37].…”