Resilience of secondary forest regrowth after slash-and-burn agriculture in central Amazonia

Abstract

This study describes forest succession following slash-and-burn agriculture in central Amazonia, based on four chronosequences (22 sites) of 2- to 25-y-old secondary regrowth and mature forest. Biomass accumulated in the form of a saturation curve: 25 y of regrowth restored half of the mature-forest biomass, 75% would be restored after an estimated 175 y. Biomass accumulation was accompanied by a rapid decrease in woody plant density and an increase of the positive skew of plant size distribution. Liana biomass share declined from 5.0% in young to 1.9% in old regrowth, and 1.3% in mature forest, whereas the share of palms was low (0.5%) in young regrowth and high in old regrowth (1.8%) and mature forest (2.2%). 25-y-old regrowth was similar with mature forest in respect to woody plant density and growth-form composition, but both the plant size distribution and the number of stems per plant differed strongly from mature forest. A moderate increase in land use had only minor effects on biomass accumulation, but profoundly changed structural characteristics of regrowth, pointing to a high vulnerability to degradation. Thus, the sustainability of slash-and-burn in central Amazonia may be lower than the rapid initial biomass accumulation would make it seem.

Development of Forest Structure and Leaf Area in Secondary Forests Regenerating on Abandoned Pastures in Central Amazônia

“…Lett.). Compared to recovery following slash-and-burn, the postpasture forests of this study recovered biomass more slowly than Piper-dominated SFs in the humid lowlands of Papua New Guinea (Hartemink 2001), more rapidly than rates reported for Bolivian lowland SFs (Steininger 2000), at similar rates for a review of forest recovery following slash-and-burn in the Tropics (Brown and Lugo 1990), and much lower than after shifting cultivation 50-100 km from our study area (Gehring et al 2005).…”

“…Gehring et al (Gehring et al 2005) found that a moderate increase in the intensity of land use had only minor effects on biomass accumulation, but affected forest structure with the biomass being more evenly distributed among size classes. In the upper Rio Negro of the Amazon basin biomass increased linearly through the first 40 yr following clearcutting and abandonment, but did not change for the next 40 yr because of the death of long-lived successional species (Saldarriaga et al.…”

“…This pattern may affect stand structure for at least 30 yr (Lucas et al 2002). The length of land use, rather than the type of land use, may be more important to predict stand structure (Gehring et al 2005). The early development of forest structure and the expression of dominance may have a long-term effect on the time needed for these forests to develop characteristics typical of primary forests.…”

Greenhouse gas emissions along a peat swamp forest degradation gradient in the Peruvian Amazon: soil moisture and palm roots effects

“…Decreased C/N ratio of litterfall with increased degradation is in agreement with observations by Feldpausch et al (2004) along a sequence of secondary forest regeneration in Central Amazonia. During early forest succession the biomass accumulates rapidly and consists mainly of easily decomposable litter and less of wood (Gehring et al 2005;Guariguata and Ostertag 2001). More readily decomposable litter may on the long-term lead to reduced peat accumulation at the degraded sites (Frolking et al 2001).…”

A Soil Burn Severity Index for Understanding Soil-fire Relations in Tropical Forests

“…Disturbance legacy includes frequency of past fires (2) or other disturbances such as slashing (39) or landslides (5). Several studies contain disturbance legacy as a source of variation to understand the role of fires in tropical forests (24,(42)(43)(44)(45) (Table 2).…”