Use of nutrient medium technique for vegetation restoration in Karst region of Southwest China

Abstract

Karst rocky desertification (KRD) is a global environmental degradation problem caused by human activities and vegetation deterioration. Vegetation restoration in KRD is very difficult due to severe water loss, soil erosion and extensive bare bedrock. For achieving vegetation restoration on bare bedrock areas of KRD, the nutrient medium technique was developed, which is based on the special hydro-geological conditions that is seasonal rainfall is abundant in Karst region of Southwest China and limestone fissures are extremely developed and rich in fissure water. The objective of this research is to investigate the feasibility of using nutrient medium technique to achieve vegetation restoration in KRD region. Through the indoor and field experiments, some properties of the nutrient medium mixture were tested, including water retention, water absorption and nutrient retention. The results showed that the moisture content on the 75th day and water absorption rate of No.2 mixture was 19.9% and 1.67mm/d, respectively, which could be used as optimum mix ratio for producing nutrient medium. The field results showed that the nutrient medium technique could effectively guarantee the survival of sapling at early age and sustainable growth at later age in the field, and the nutrient medium had less nutrient loss. This novel approach can retain and absorb moisture, and saplings do not need artificially supply water and fertiliser in the dry season, and the use of nutrient medium technique to achieve vegetation restoration in KRD region seems to be a feasible option.