Maize Cultivation Three Hundred Years Ago Triggered Severe Rocky Desertification in Southwest China

Abstract

Understanding the forest evolution is vital to answering the reforestation potential in karst areas. Here, we present the first‐ever pollen record in karst depression sediment, combined with comprehensive dating methods (137Cs, 210Pbex, and 14C) and historical documents, to reveal plant change history in southwest Guangxi, a severe rocky‐desertification region. We inferred three stages of “virgin forest–deforestation–sparse tree planting” over the past three centuries. Before the 1780s, the barren mountains used to be a lush mixed broadleaf forest probably. However, maize cultivation, along with explosive population growth and migration, accelerated mountain reclamation and deforestation, leading to severe rocky desertification since the 1780s, featured by the co‐occurrence of Zea pollen appearance and Dicranopteris spore surge from 0.92% to 12.18%. Since the 1930s, sparse tree planting began, as Cupressaceae/Taxodiaceae pollen abruptly increased by 32%. Our study is significant in understanding the rocky desertification causes and guiding ecological restoration in the region.