4.2.1. The Current Status of Grassland Ecosystem for KDC

Karst areas are very fragile and prone to ecological degradation due to their unique binary three-dimensional geological structure, of which karst desertification is an extreme manifestation of ecological degradation [229]. In the past 30 years, the KDC in southern China has achieved remarkable results in ecological environment and ecological restoration, but there is an urgent need to improve the stability of the KDC ecosystem and ecosystem service function [52,235]. Grasslands of the KDC are dominated by artificial grasslands and supplemented by improved grasslands, which constitute an important ecosystem in karst areas [229]. The artificial grasses in the KDC areas mainly include monoculture *Dactylis glomerata* L., *Lolium perenne* L. and *Medicago sativa* L. Grasslands have a monoculture planting structure and weak disease resistance, and the resulting artificial grass ecosystem is extremely fragile. This is mainly due to farmers' pursuit of high forage yields. Thus, while the artificial grassland has brought high economic income to farmers for a short period of time, its ability to provide ecosystem services is gradually diminishing. In addition, the degraded grassland is dominated by replanting white clover by government aircrafts. However, due to the overgrazing behavior of farmers in recent years, the replanted degraded grassland is difficult to recover, and only some grass species that are resistant to gnawing and trampling are propagated, resulting in the difficult recovery of the grass species structure of degraded grassland and low stability of the ecosystem.

In the process of KDC and ecological restoration, grass is the pioneer plant for vegetation restoration and ecological environment improvement [64]. Therefore, optimizing the structure and enhancing the stability of grassland ecosystems for KDC is of great significance for the sustainable development of regional ecological environments and promoting the virtuous cycle of regional eco-industry.

#### 4.2.2. Inspiration for Improving the Ecosystem Service Capacity of Grasslands for the KDC

Due to its inherent sensitivity and fragility, the ecosystem structure and function of the grassland ecosystem in the KDC area are improper and the stability of the ecosystem is poor [236,237]. In the context of promoting the world's desertification management and global sustainable greening, how to consolidate and stabilize the effectiveness of KDC and, at the same time, optimize the structure of desertification-control grassland ecosystems, guaranteeing the stability of the ecosystem and enhancing the ecosystem service capacity is a key issue that needs to be solved in the KDC area [238]. In view of this, based on the premise of sorting out the structure and stability of global grassland ecosystems, this paper drew on the above key scientific issues of structure optimization, stability enhancement and the interaction between structure and stability and, combined with the regional characteristics of karst desertification and the grassland status of KDC, proposes three insights for the enhancement of the ecosystem service capacity of grassland in the KDC area.
