Tree plantation and soil water conservation enhances climate resilience and carbon sequestration of agro ecosystem in semi-arid degraded ravine lands

Abstract

Agro ecosystems in degraded lands are subjected to climate change impacts throughout the globe. Previous work in degraded lands has focused on afforestation and soil conservation, which has obvious limitations in terms of generality and scope of application for production systems in climate change scenario. A key challenge in degraded lands is to develop climate smart systems those are resilient to extreme weather and have high potential for carbon sequestration. Therefore, we examined the effectiveness of Sapota trees (Achras zapota) and regional crops/grasses (annuals) combination (agroforestry) with soil water conservation (SWC) for enhancing climate resilience and carbon sequestration of agro ecosystem in semi-arid degraded lands of Western India. The experiment was conducted for eight years (2010–2017) in four systems: (i) Sapota + Crops on terrace (SCTe) (ii) Sapota on terrace (STe); (iii) Sapota and Trenches on slope (STrS); and (iv) Sole Sapota on slope (SS) and their performance was assessed during different annual rainfall events (Normal, Heavy, High, Abnormal, Drought). Our findings explained that, among all the annual rainfall events, drought resulted in the mortality of Sapota tree and reduction in biomass production of the grasses, while, terrace and trench measures reduced the tree mortality and enhanced the grass biomass production. Plant population of Cowpea and Castor crops were recorded significantly higher during normal rainfall, but a decline was observed during rest of the rainfall events. Height and diameter growth increment in Sapota was recorded higher during normal rainfall compared to the drought period. SWC measure such as terraces and trench contributed higher growth increment and biomass production in Sapota tree, compared to sole slope, under all the rainfall conditions. Rainfall variability also affected the Cowpea and Caster and their yield was recorded maximum during normal rainfall and minimum during drought period, respectively. Moreover, SWC measure such as terrace and trench enhanced fruit yield of Sapota during the drought period. These measures also improved carbon stock and carbon sequestration in Sapota and grasses during the eight years. Overall, carbon stock and carbon sequestration in plants and soil were observed greater in uncultivated terrace (STe), followed by cultivated terrace (SCTe) and trench (STr) systems, respectively, while, overall, their lower value was observed in slope system (SS). The results suggested that tree and annuals combination (agroforestry) along with soil water conservation measures enhanced agro ecosystem resilience to extreme weather and improved the carbon stock and sequestration potential. Therefore, soil and water conservation should be considered, along with only those trees and annuals, which have the capability to enhance climate resilience and potential of high carbon sequestration, in semi-arid climate change vulnerable degraded ravine landscape.