Negative Trade-offs Between Community Forest Use and Hydrological Benefits in the Forested Catchments of Nepal's Mid-hills

Manoj Badu,Roshan Man Bajracharya,Chandra Prasad Ghimire,Wayne S Meyer,Ian Nuberg

doi:10.1659/mrd-journal-d-18-00066.1

Manoj Badu, Roshan Man Bajracharya + Show 3 more

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https://doi.org/10.1659/mrd-journal-d-18-00066.1

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Abstract

Widespread community forestry practices in Nepal's mid-hills catchments involve removal of forest products—including firewood, litter, fodder, and medicinal herbs—by the local communities. Uncertainty is growing about how sustainable the management of these catchments is and whether it can meet traditional needs and maintain ecosystem services, particularly water. As part of a broader study on the hydrological effects of community forestry practices, we measured selected soil properties, including saturated hydraulic conductivity (Ks), bulk density (BD,) and soil organic carbon (SOC) across 4 depths (0–10, 10–20, 20–50 and 50–100 cm) in 3 types of community forest sites—broadleaf, pine-dominated, and mixed—in the Roshi Khola catchment of Kavre district. The same measurements were made at a minimally disturbed religious forest site in the catchment that had higher Ksvalues than the mixed and broadleaf sites, signifying a lower degree of forest use-related disturbance. Likewise, SOC values for the religious forest were significantly higher (P < 0.05) and BD values significantly lower than the pine-dominated and mixed forest sites, particularly at shallower depths (0–50 cm). Importantly, comparison of the median Ksvalues (16–98 mm h–1) with rainfall intensities measured at the catchment showed the less intensively used pine-dominated site to be conducive to vertical percolation with possible greater contributions to subsurface storage even during high-intensity rainfall events. These results highlight the critical role of forest use practices in landscape hydrology and have implications for the management of the forested catchments in the broader Himalayan region, particularly in relation to the negative local perceptions of the role of pine plantations on declining water resources.

Highlights

During the early half of the 20th century, forest to farmland conversion and high local demand for forest products, including timber, firewood, livestock fodder, and compostable litter, caused significant loss of forest cover in Nepal’s mid-hills and gave rise to the widely publicized but contested ‘‘theory of Himalayan environmental degradation’’ (Gilmour 1988; Ives 2004; Hofer and Messerli 2006)
More than half of the mid-hills catchments contain naturally grown or planted species of broadleaf and pine, more than two-thirds of which are managed by nearly 7 million local users organized as members of the Community Forest User Groups (DFRS 2015)
While site attributes could account for this difference, the higher values for the mixed forest suggests increased foot traffic– related compaction that occurs due to the site’s proximity to the road (Figure 2F)

Summary

Introduction

During the early half of the 20th century, forest to farmland conversion and high local demand for forest products, including timber, firewood, livestock fodder, and compostable litter, caused significant loss of forest cover in Nepal’s mid-hills and gave rise to the widely publicized but contested ‘‘theory of Himalayan environmental degradation’’ (Gilmour 1988; Ives 2004; Hofer and Messerli 2006). The reforestation programs largely used fast-growing species of pine, such as Pinus roxburghii, due to the species’ high adaptability to the nutrient-poor soils of the mid-hills (Gilmour et al 1990). More than half (over 2.2 million ha) of the mid-hills catchments contain naturally grown or planted species of broadleaf and pine, more than two-thirds of which are managed by nearly 7 million local users organized as members of the Community Forest User Groups (hereafter CFUGs) (DFRS 2015)

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