Tree diversity and standing carbon stocks in smallholder forests of Ciamis Regency, Indonesia: Effects of cropping patterns and elevations

Smallholder forests (SFs) provide critical ecosystem services by supporting biodiversity conservation and carbon (C) sequestration in tropical landscapes, yet how these functions vary across management systems and environmental gradients remains poorly understood. We investigated the effects of three main cropping patterns (tree crops, mixed-tree lots, and agrisilviculture) on tree diversity and aboveground C stocks across three elevation zones (< 200 masl, 200–500 masl, > 500 masl) in Ciamis, West Java, Indonesia. Data were collected from 150 plots (50 plots per elevation class), which were unevenly distributed across the three cropping patterns. Trees were classified into three growth phases (saplings, poles, and mature trees), and DBH and total height were measured to estimate C stocks, while tree diversity was assessed using standard diversity indices. The results showed that mixed-tree lots and agrisilviculture supported higher species richness than tree crops systems, which exhibited lower diversity and greater dominance by a limited number of species. Carbon stocks varied significantly among cropping patterns and growth phases, but not across elevation zones, suggesting that management-associated cropping patterns and stand structural attributes exerted a stronger influence on aboveground C storage than topographic variation. Mean C stocks ranged from 41–57 MgC ha -1 in mixed-tree lots and 37–51 MgC ha -1 in tree crops, compared with 23–32 MgC ha -1 in agrisilviculture systems. Overall, these findings highlight the potential of mixed-tree lots to simultaneously promote biodiversity conservation and C storage in tropical smallholder forest landscapes, though the results should be interpreted within the scope of this observational study, as economic performance and long-term sustainability were not evaluated.