Shifting cultivation in the upland secondary forests of the Philippines: biodiversity and carbon stock assessment, and ecosystem services trade-offs in land-use decisions

Abstract

Secondary forest comprises a large area in the tropical region, and it has increasingly believed that the future of tropical forests depends on the effective management of such second growth forests largely modified by human activity. In tropical secondary forests, shifting cultivation, swidden or slash-and-burn is a major land-use that has been attributed to causing large scale deforestation and forest degradation. This view has been embedded in many policy documents, although there are conflicting views within the literature as to the impact of shifting cultivation on secondary forest dynamics. This is largely due to the complex nature of this land-use that makes any generalisation difficult.In the Philippines -a country overwhelmed with rich biodiversity and species endemism, shifting cultivation is locally known as kaingin and represents a dominant land-use in upland rural areas. Although not officially recognised, it has a major contribution to the livelihoods and food security of smallholder rural farmers. After post-logging secondary forests, post-kaingin secondary forests also form the largest group of secondary forests in the Philippines. This thesis based on an empirical study where secondary forest dynamics after shifting cultivation were investigated in an upland area in the Leyte Island, the Philippines.Chapter 2 of my thesis is a synthesis that reports, spatial and temporal distribution of research on shifting cultivation using a systematic literature search protocol, and the key findings of research in conservation biology, plant ecology, soil nutrients and chemistry, and soil physics and hydrology. A bias towards research on anthropology and/or human ecology was found with most research reported from tropical Asia-Pacific region. A great variation in findings on selected forest/environmental parameters was also evident.In Chapter 3, I report a field study where tree diversity, species composition and forest structure and their recovery in secondary forests after shifting cultivation was investigated along a fallow/shifting cultivation land-use gradient. Twenty-five individual sites representing four different fallow categories and old-growth forest as control were surveyed. Tree species richness was significantly higher in the oldest fallow sites while other diversity and forest structure indices were higher in the old-growth forest sites. A homogeneous species composition was found in older fallow sites and in old-growth forest. It was found that secondary forests disturbed by shifting cultivation recovers rapidly in terms of species richness and abundance, and that patch size is a strong predictor of this recovery.Uncertainties in the aboveground biomass carbon in degraded secondary forests after shifting cultivation are one of the main issues hindering its inclusion in the current REDD+ negotiations. In Chapter 4, the distribution and recovery of biomass carbon along a fallow gradient were reported from my study sites. It was found that aboveground total biomass carbon and living iii w...

Indigenous Knowledge and Forest Succession Management in the Brazilian Amazon: Contributions to Reforestation of Degraded Areas

“…Regarding the impacts on the regeneration of fallows, the Kawaiwete and Ikpeng local knowledge seems to value preventive care during cultivation phases aiming to prevent the forest from being degraded, instead of resorting to concepts or ways of restoring exhausted environments. In this sense, traditional local knowledge seems to indicate rules or "care" in the way environments should be managed based on resilience limits, as observed for other places (Lugo, 1995;Camacho et al, 2012;Chazdon, 2014a;Magnuszewski et al, 2015;Chazdon and Guariguata, 2016;Brancalion et al, 2016;Mukul, 2016;Vásquez-Grandón et al, 2018).…”

“…Forest and agricultural management often leads to changes in species composition and in soils (Smith, 1980;Balée, 1993;Heckenberger and Neves, 2009;Arroyo-Kalin, 2010;Junqueira et al, 2011;Woods et al, 2013;Schmidt et al, 2014;Levis et al, 2018Levis et al, , 2020, and are based on a deep knowledge of ecological dynamics and on social and cultural rules (Berkes and Berkes, 2009). The shifting cultivation practiced by indigenous Amazonian peoples depends on the multifunctional management of the landscape during the cultivation phase (van Vliet et al, 2012;Mukul, 2016), which includes the simultaneous cultivation of several cultivated/domesticated and semi-domesticated species (Hett et al, 2012). The combination of social and ecological dynamics leads to different successional trajectories (Wangpakapattanawong et al, 2010;Chazdon, 2014b;Chazdon and Uriarte, 2016;Uriarte and Chazdon, 2016).…”

Carbon and Biodiversity Outcomes under Divergent Management Scenarios in Shifting Cultivation Landscapes in the Upland Philippines

“…In each of our study sites we identified tree species that were at least 5 cm at dbh (diameter at breast height) and measured diameter and height. More about our survey design and data collection can be found at Mukul (2016).…”

“…Shifting cultivation, locally termed as kaingin is a widespread land-use in the Philippines (Kummer 1992). It is also a major livelihood strategy to many smallholder farmers living in the remote rural areas of the country (Mukul 2016;Herbohn et al 2014). However, alike many other tropical countries, major forestry policies in the Philippines have attempted to impose restrictions on kaingin, based on the assumption that it has detrimental impacts on the environment (Saurez and Sajise 2010; Lawrence 1997).…”

Socioeconomic Drivers of Land Use Intensification in Fiji Islands: A Geographical Approach

“…Short fallows trigger yield declines (Kafle 2011). After shifting cultivation both the fallow age and land use intensity influence the recovery of native trees diversity (Mukul 2015); the forest degradation and subsequent rural poverty worsens in a cycle when there are few economic alternatives, unstable or low market prices, no incentives for innovation, and successive subdivision of land at the death of the owner (Chayanov 1966) (figure 1).…”