Data for 'The value of shifting cultivation for biodiversity in Northeast India'

Shifting cultivation is a widespread land-use in many tropical countries that also harbours significant levels of biodiversity. Increasing frequency of cultivation cycles and expansion into old-growth forests have intensified the impacts of shifting cultivation on biodiversity and carbon sequestration. We assessed how bird diversity responds to shifting cultivation and the potential for co-benefits for both biodiversity and carbon in such landscapes to inform carbon-based payments for ecosystem service (PES) schemes. We conducted this study in Nagaland, Northeast India. We surveyed above-ground carbon stocks and bird communities across various stages of a shifting cultivation system and old-growth forest using composite carbon sampling plots and repeated point counts directly overlaying the carbon plots in both summer and winter. We assessed species diversity using species accumulation and rarefaction curves based on Hill numbers. We fitted a linear mixed-effect model to assess the relationship between species richness and fallow age. We also examined possible co-benefits between carbon and biodiversity from fallow regeneration in terms of relative community similarity to old-growth forest across carbons stocks. Farmland and secondary forests regenerating on fallowed land had similar bird species richness to old-growth forests in summer and relatively higher species richness in winter. Within regenerating fallows, we did not find any strong evidence that fallow age influenced bird species richness. Bird community resemblance to old-growth forest increased with secondary forest maturity, correlating also with carbon stocks in summer. However, bird community assemblage did not show a strong association with habitat types and carbon stocks during winter. This study underscores the important role of traditional non-intensive shifting cultivation in providing refuges for biodiversity within heterogeneous habitat mosaics. Effectively managing these landscapes is crucial for both biodiversity conservation and carbon sequestration in the subtropics.

轮歇农业（shifting cultivation）是诸多热带国家广泛应用的土地利用模式，此类区域同时孕育着高度丰富的生物多样性。耕作周期愈发频繁、垦殖范围扩张至原始林，使得轮歇农业对生物多样性与碳固存（carbon sequestration）的影响进一步加剧。本研究评估了鸟类多样性对轮歇农业的响应规律，以及此类景观中生物多样性与碳固存的协同效益潜力，以期为基于碳的生态系统服务付费（PES）方案提供决策参考。本研究于印度东北部的那加兰邦开展。我们通过组合碳样方（composite carbon sampling plots）以及在夏季与冬季对碳样方进行重复点计数调查，对轮歇农业系统不同演替阶段与原始林的地上碳储量及鸟类群落开展了系统采样；基于希尔数（Hill numbers）构建物种累积与稀疏曲线（species accumulation and rarefaction curves）以评估物种多样性，并拟合线性混合效应模型（linear mixed-effect model）探究物种丰富度与休耕年限的关联。此外，我们以鸟类群落与原始林的相对群落相似度为评价指标，分析了休耕地再生过程中不同碳储量水平下碳固存与生物多样性间的潜在协同效益。夏季，休耕地上再生形成的农田与次生林的鸟类物种丰富度与原始林相当，冬季则相对更高；在再生休耕地中，未发现休耕年限对鸟类物种丰富度存在显著影响的有力证据。夏季，鸟类群落与原始林的相似度随次生林成熟度提升而升高，且该趋势与碳储量存在相关性，但冬季鸟类群落组成并未与生境类型及碳储量呈现显著关联。本研究凸显了传统非集约型轮歇农业在异质生境镶嵌体中为生物多样性提供庇护所的重要作用，对此类景观进行有效管理，对于亚热带地区的生物多样性保护与碳固存均至关重要。