Kaleka Agroforest in Central Kalimantan (Indonesia): Soil Quality, Hydrological Protection of Adjacent Peatlands, and Sustainability

Yosefin Ari Silvianingsih,Didik Suprayogo,Kurniatun Hairiah,Meine Van Noordwijk

doi:10.3390/land10080856

Abstract

Increased agricultural use of tropical peatlands has negative environmental effects. Drainage leads to landscape-wide degradation and fire risks. Livelihood strategies in peatland ecosystems have traditionally focused on transitions from riverbanks to peatland forests. Riparian ‘Kaleka’ agroforests with more than 100 years of history persist in the peatlands of Central Kalimantan (Indonesia), where large-scale open-field agricultural projects have dramatically failed. Our field study in a Dayak Ngaju village on the Kahayan river in the Pulang Pisau district involved characterizing land uses, surveying vegetation, measuring soil characteristics, and monitoring groundwater during a period of 16 months. We focused on how local practices and farmer knowledge compare with standard soil fertility (physical, chemical, biological) measurements to make meaningful assessments of risks and opportunities for sustainable land use within site-specific constraints. The Kaleka agroforests around a former settlement and sacred historical meaning are species-rich agroforests dominated by local fruit trees and rubber close to the riverbank. They function well with high wet-season groundwater tables (up to −15 cm) compatible with peatland restoration targets. Existing soil quality indices rate the soils, with low soil pH and high Alexch, as having low suitability for most annual crops, but active tree regeneration in Kaleka shows sustainability.

Highlights

Soils of a wide range of physical, chemical and biological soil characteristics can be sustainably used, as long as the vegetation is adapted to the root environment, and if the long-term carbon, nutrient, and water balance is respected by matching inputs to output [1,2,3]
−10 day), and two the overall drainage patterns (InterceptEt 0.3; GWdrainfrac: 0.3 per two weeks). Acceptable fits for this model, were obtained with drain-depths that varied from −40 cm for FAF, rubber agroforest (RAFo) and RAFy, via −60 cm for rubber monoculture (RMO) to −110 cm for open-field agriculture (OFA) (Table 1)
The fruit agroforest functioned at an average groundwater level of −33 cm, and measurements indicated that, 55 percent of the time, it exceeded the −40 cm level that is mandated for peatlands

Summary

Introduction

Soils of a wide range of physical, chemical and biological soil characteristics can be sustainably used, as long as the vegetation is adapted to the root environment, and if the long-term carbon, nutrient, and water balance is respected by matching inputs to output [1,2,3]. Soil health and soil quality constrain land use depending on the management applied. The direction of change, interpreted as degradation or restoration, is more relevant to local land users than absolute measurable quantities [4]. Impacts of plot-level change can reach beyond the plot scale of a direct land user and affect ecosystem services ‘downstream’ [5,6]. Local people had to deal with and make the best of local conditions through their land use choices, and developed locally calibrated process-level knowledge, spatially explicit indicators, and adjustable management options, even though their site conditions would be considered to be sub-optimal if other choices were available [9,10]

Results

Discussion

Conclusion