Assessing the Ecological Success of Restoration by Afforestation on the Chinese Loess Plateau

TLDR

Afforestation has been a key strategy for preventing soil erosion on the Chinese Loess Plateau for four decades. This study evaluated the ecological success of afforestation by comparing afforested plots with pre‑afforested croplands and natural recovery sites in a typical Loess watershed. Ecosystem responses were assessed through vegetation structure, plant diversity, and key soil processes including moisture, nutrients, and anti‑erodibility. Afforested sites showed markedly higher vegetation structure, species diversity, soil nutrients, and anti‑erodibility than croplands, yet offered little advantage over natural recovery and caused increased soil desiccation, indicating that natural revegetation may be a more sustainable restoration approach.

Abstract

Afforestation has been accepted as a key measure for preventing soil erosion on the Chinese Loess Plateau for 40 years. In this study, we assessed the ecological success of afforestation by comparing afforested with pre‐afforested (croplands) and natural recovery sites in a typical watershed on the Loess Plateau. We evaluated the ecosystem response in terms of vegetation structure, plant diversity, and several key ecological processes of soil moisture, soil nutrients, and soil anti‐erodibility. Compared with the croplands, we found that the following indexes were significantly enhanced in afforested sites: vegetation structure and species diversity (species richness, Margalef index, Shannon–Wiener index, and Sorensen's similarity index), soil nutrients (organic carbon, total nitrogen, extractable ammonium nitrogen, available potassium, and available phosphorous), and soil anti‐erodibility indexes (water‐stable soil aggregates, mean weight diameter, and the ratio of soil structure dispersion). Afforestation offered few additional advantages when compared with natural recovery sites. More importantly, afforestation had significant negative effects on soil desiccation, with negative impacts on the long‐term sustainability of these ecosystems. In order to develop self‐sustaining and functional ecosystems, our results suggest that natural revegetation offers a more adaptive and appropriate method of ecological restoration on the Loess Plateau.