Purpose This paper aims to use the composite fingerprinting method to reconstruct the environmental history after the Grain-for-Green Project and to provide effective sediment management and soil erosion-control strategies. Materials and methods This study used a composite fingerprinting method based on 45 geochemical properties and a mixing model to investigate sediment core changes in the sediment source in an agricultural catchment with little native vegetation. The samples consisted of 77 source samples (i.e., gully, grassland, forest, cropland, and fallow land) and five sediment cores. Genetic algorithm (GA) optimization has been recently used to find the best optimum source contribution to sediments. Results and discussion The results demonstrate that gully is the main sediment source in this catchment, constituting 34.7 %, followed by cropland (28.2 %), forest (21.5 %), grassland (12.7 %), and fallow land (2.9 %). However, the relative contribution of each source type was variable in all five sediment cores. The sediment that derived from grassland was relatively stable in the five cores. The relative contribution of forest was higher in the downstream portion of the check dam and lower in the upstream portion and gradually increased in the direction of the runoff pathway. As the forest matured, the sediment that derived from the forest gradually decreased. Changes in the hydro-ecological environment would lead to the leaf litter and understory being poorly developed and the soil being bare in the forest, making it more vulnerable to erosion. Conclusions Reforestation and fallow are the key ecological strategies for reducing soil erosion. However, at the beginning of the Grain-for-Green Project, the young forest contributed 21.5 % of the sediment, indicating that natural fallow may be a better-designed sediment management and soil erosion-control strategy.
Grain-for-Green program: conversion to natural fallow land - the plants in the fallow land were natural species (i.e., grasses, forbs, herbs and shrubs, Fig. 3d)
Climate change impacts | Effect of Nbs on CCI | Effect measures |
---|---|---|
Soil erosion | Positive | sediment fingerprinting - sediment cores in catchment sites were analyzed to determine the contribution of each land-use to the collected sediments (to see how much was eroded from each land-use) |
Hujiawan catchment (36.4°N to 36.6°N, 109.5°E to 109.9°E) in Yanchang County of Shaanxi Province on the Loess Plateau and covered a drainage area of 27 km2 (Fig. 1).
Grain-for-Green program: artificial forests - non-native trees (Robinia pseudoacacia) were planted in single-species plantations that were almost 15 years old ... much of the herbaceous vegetation (i.e. grasses, forbs, and herbs) was manually removed from under the trees to promote tree growth by reducing competition for moisture
Climate change impacts | Effect of Nbs on CCI | Effect measures |
---|---|---|
Soil erosion | Positive | sediment fingerprinting - sediment cores in catchment sites were analyzed to determine the contribution of each land-use to the collected sediments (to see how much was eroded from each land-use) |
Hujiawan catchment (36.4°N to 36.6°N, 109.5°E to 109.9°E) in Yanchang County of Shaanxi Province on the Loess Plateau and covered a drainage area of 27 km2 (Fig. 1).