Ecological Stoichiometric Characteristics of Plant–Soil–Microorganism of Grassland Ecosystems under Different Restoration Modes in the Karst Desertification Area

Abstract

C, N and P are the key biogenic elements of terrestrial ecosystems, and their biogeochemical processes regulate nutrient cycling and play a key role in restoring degraded ecosystems. In this paper, the grassland ecosystem under artificial restoration measures (Dactylis glomerata (DG), Lolium perenne (LP), Lolium perenne + Trifolium repens (LT)), and the natural restoration measures (NG) in a typical karst plateau desertification control area of southwest China, were taken as the research object. The C, N, and P concentrations and the ecological stoichiometry of the plant–soil–microorganism system in grasslands under different restoration measures in the karst desertification area were explored. We established the following findings: (1) Compared with NG, the C, N and P concentrations of plants and soil in DG, LP and LT were higher, and LT was the highest. (2) The microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and microbial biomass phosphorus (MBP) concentrations in LT was also the highest. (3) The C:N ratio of plant and soil indicated that the N mineralization and nutrient release rate of DG, LP and LT were stronger than that of NG, and the plant growth of NG was most seriously limited by nitrogen. The N:P ratio in plant and soil indicated that the grassland was limited by P in the four treatments. (4) The result of correlation analysis showed that the cycling process of C, N and P in the plant–soil–microorganism system was coupled, and that the elements closely affected each other. In general, the effect of artificial restoration on a degraded ecosystem was relatively better than the natural restoration for increasing plant, soil and microbial nutrient concentrations, especially in the mixed-seed ecosystem of leguminous and gramineous forage. However, in the future, grassland management, appropriate N fertilizer or N-fixing plants and P fertilizer should be considered to improve the limitation of plant N and P, so as to realize the sustainable development of grasslands and the restoration of degraded ecosystems in the karst desertification control area.

Soil Bacterial Community Structure and Physicochemical Influencing Factors of Artificial Haloxylon ammodendron Forest in the Sand Blocking and Fixing Belt of Minqin, China

“…Considering its structurally intricate and non-homogeneous nature, soil plays a pivotal role in sustaining terrestrial ecosystem functions and services [10]. Soil nutrients are limited within desert ecosystems, necessitating the implementation of ecological mechanisms that expedite the soil element cycling process, regulate soil fertility transformation, and enhance the absorption and utilization of plant nutrients [11]. These mechanisms are crucial for ensuring the sustainable restoration of desert vegetation productivity and effectively mitigating land desertification [12].…”

“…The burgeoning popularity of the high-throughput sequencing of 16S rRNA and the utilization of PICRUSt2 macrogenomic function prediction technologies present innovative methodologies for unraveling the intricate microbial community structure that underlies the functional equilibrium of diverse soil ecosystems [21,22]. The study determined that the introduction of desert flora exerts a momentous influence on the micro-ecological rehabilitation of arid and semi-arid desert soils [9,11,17,19]. For instance, in the Horqin sandy land, the rehabilitation process involving Caragana microphylla vegetation not only contributed to enhancements in vegetation coverage and diversity but also entailed a significant enrichment of the soil microbial community structure [23].…”

Mapping Foliar C, N, and P Concentrations in An Ecological Restoration Area with Mixed Plant Communities Based on LiDAR and Hyperspectral Data

“…A high C:N ratio implies a relatively higher content of C and a lower content of N in the leaves. This may occur in environments with limited N supply, or when plants grow under conditions rich in C but deficient in N. Plants with a high C:N ratio exhibit high N use efficiency but grow slowly because they require more time to acquire sufficient N to support growth [73]. However, a low C:N ratio signifies a relatively low C content and a higher N content in the leaves.…”

“…This typically indicates that the studied plants have an ample N supply, possibly due to being in an N-rich environment or receiving N fertilizer. Plants with a low C:N ratio have rapid decomposition traits and faster growth, with a relatively lower demand for C [73]. Plants with a moderate C:N ratio have a balanced content of C and N in their leaves.…”

Suitability of agronomic water saving in karst areas and its enlightenment in the karst desertification control

“…In China, karst areas are mainly distributed in its southwest regions, centered on the Guizhou plateau. It is the widest area with exposed carbonate rocks in the world (more than 0.54 million km 2 ), being home to 220 million people [ 3 , 4 ]. It is also one of the most ecologically fragile regions in the world [ 5 ].…”