Identification of suitable vegetation restoration areas and carrying capacity thresholds on the Loess Plateau.

The Loess Plateau is one of the most ecologically fragile areas in the world. It has long faced the twin dilemmas of ecological degradation and water resource shortage. In recent decades, large-scale vegetation restoration projects have been carried out on the Loess Plateau with the aim of improving the ecological environment. However, as the vegetation cover increases, the water consumption of vegetation also increases, which further exacerbates the problem of water resource shortages. In order to effectively utilize water resources and balance the relationship between forests and water use, suitable vegetation restoration areas were identified on the Loess Plateau by constructing a vegetation suitability evaluation model based on multiple index factors (precipitation, temperature, altitude, slope, aspect, soil texture, soil depth, soil organic matter and ecological water consumption). The suitable restoration area results are given as follows: trees comprised 18.58% of the total vegetation coverage area and were mainly distributed across the central and southern Loess Plateau; shrublands comprised 32.58% of the total vegetation coverage area and were mainly distributed across the northern part of the Loess Plateau; and grasslands comprised 48.84% of the total vegetation coverage area and were mainly distributed across the western and northeastern regions of the Loess Plateau. On this basis, the Eagleson model was used to identify the bearing capacity of vegetation in the suitable restoration area. The optimal simulated vegetation coverage values of the suitable restoration areas are given as follows: grassland, 0.246-1.000; shrubland, 0.186-0.783; and trees, 0.137-0.868. These results can help guide the local ecological environment construction, offer theoretical support for the ecological restoration of similar areas and provide a scientific reference for the effective use of water resources and vegetation restoration on the Loess Plateau.