Manfred Denich

Legacy of fire slows carbon accumulation in Amazonian forest regrowth

Amazonian farmers and ranchers use fire to clear land for agriculture and pasture as part of extensive land-use strategies that have deforested 500 000 km2 over the past 25 years. Ash from burning biomass fertilizes crops and pastures, but declining productivity often occurs after a few years, generally leading to land abandonment and further clearing. Subsequent forest regrowth partially offsets carbon emissions from deforestation, but is often repeatedly cleared and burned. In the first quantitative, basin-wide assessment of the effect of repeated clearing and burning on forest regrowth, our analysis of data from 93 stands at nine locations across the region indicates that stands with a history of five or more fires suffer on average a greater than 50% reduction in carbon accumulation. In the absence of management interventions, Amazonian landscapes dominated by this pronounced legacy of fire are apt to accumulate very little carbon and will remain highly susceptible to recurrent burning.

Carbon storage and root penetration in deep soils under small-farmer land-use systems in the Eastern Amazon region, Brazil

The north-east of Pará state in the Eastern Amazon of Brazil was settled over 100 years ago. Today the region is an agricultural landscape with variously-aged secondary vegetation and fields with annual cultures, plantation crops and pastures. The effect of these different land covers on carbon sequestration as well as on water and nutrient extraction remain subject of debate. Therefore, we assessed the importance of land use on soil carbon stocks by measuring various C fractions and root biomass (0–6 m) in slash-and-burn systems and (semi-) permanent cultures. An extensive root system down to at least 6 m depth was present under various secondary vegetation stands and slashed and burned fields recently taken into cultivation as well as under a primary forest. Shallower rooting patterns were evident under (permanent) oil palm (4.5 m) and (semi-permanent) passion fruit plantations (2.5 m). Carbon storage in soils of traditional slash-and-burn agriculture up to 6 m depth (185 t ha-1) was not significantly lower than under a primary forest (196 t ha-1) but declined significantly under (semi-) permanent cultures (to 146–167 t ha-1). Compared to above-ground C losses, soil C losses due to slash-and-burn agriculture may thus be small. This is an argument for maintaining the secondary vegetation as part of the agricultural land-use system, as the root system of its trees is conserved and thus C is sequestered also at greater depth.

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

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 alter an estimated 17 5 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.

Floristic inventory of secondary vegetation in agricultural systems of East-Amazonia

Small farmers in the Bragantina (East-Amazonia, Brazil) traditionally apply a rotation of 2 years cultivation and 4–10 years forest fallow. More recently introduced pepper plantations fell fallow after fungus hazards. We studied the floristic composition of this young secondary vegetation by means of 92 vegetation relevés in 58 plots of forest fallow and 34 plots of pepper fallow with sizes ranging from 40 to 300 m2. The age of the fallow vegetation ranged from 4 months to 10 years. We found 673 species belonging to 97 families. The list of plant species presented in the Appendix totals 827 species, including species collected in additional field surveys. The species are registered with scientific and local names as well as growth forms. The families with the largest numbers of species were Myrtaceae (34 species), Leguminosae (87), Sapindaceae (17), which contain mainly trees and shrubs, and Bignoniaceae (29), Connaraceae (12), Smilacaceae (22) with mainly vines, the forb dominated families Asteraceae (25), Euphorbiaceae (21), Rubiaceae (20), and Cyperaceae (16) and Poaceae (35). A comparison with local and regional inventories shows similarities to fallow vegetations and secondary forests, and floristic distance to primary forests.

Regeneration Response of Juniperus procera and Olea europaea subsp cuspidata to Exclosure in a Dry Afromontane Forest in Northern Ethiopia

Abstract The Afromontane forests of northern Ethiopia have been degraded and fragmented for centuries. Recently, efforts have been made to restore these forests by protecting them from livestock interference. In this study, the natural regeneration of Juniperus procera Hochst. ex Endl. and Olea europaea L. subsp cuspidata (Wall. ex G. Don) Cif. is investigated under protected conditions after 3 years of enclosure and under open management systems in a dry Afromontane forest in northern Ethiopia. Data on the floristic and structural compositions of the vascular plants were collected using 32 randomly selected plots (20 m × 20 m), while nested plots (10 m × 10 m) were used to investigate the seedling bank at the protected and adjacent open sites. The results reveal that there was a significantly higher regeneration of O. europaea on the protected site than on the open site (P  =  0.01). However, there was no significant difference between the 2 sites for J. procera (P  =  0.16). Thus, protecting the degraded forest in northern Ethiopia seems to be an appropriate management option for the regeneration of O. europaea. The regeneration status of J. procera at both sites is poor, which indicates that protecting the forest from livestock and human disturbance is unlikely to lead to regeneration of this species. Further investigation of other factors that hinder the regeneration of J. procera is therefore recommended.

Bioenergy, food security and poverty reduction: trade-offs and synergies along the water-energy-food security nexus

This article provides a review of trade-offs and synergies of bioenergy within the water–energy–food security nexus, with emphasis on developing countries. It explores the links of bioenergy with food security, poverty reduction, environmental sustainability, health, and gender equity. It concludes that applying the nexus perspective to analyses of bioenergy widens the scope for achieving multiple-win outcomes along the above aspects.

Bioenergy, Food Security and Poverty Reduction: Mitigating tradeoffs and promoting synergies along the Water- Energy-Food Security Nexus

Modern bioenergy is a core ingredient of sustainable economic development as it plays an important role in poverty reduction and green growth. This makes bioenergy innovations critical, especially in developing countries where many households and rural communities rely on traditional bioenergy. Managing the multiple tradeoffs among bioenergy use, agricultural productivity, and ecosystem functions is a major development challenge. Addressing this challenge requires the identification of the drivers, tradeoffs and impacts of bioenergy production, trade and use in the Water, Energy and Food Security Nexus. The key objective of this paper is to provide an analytical framework and assess the track record of policy actions to stimulate modern bioenergy innovation in order to achieve multiple-win outcomes in terms of poverty alleviation, improved health and gender empowerment and environmental sustainability. We begin by describing the global trends and drivers in bioenergy production, trade and use. Secondly, we review the state of the art on impacts and links of bioenergy with the other Nexus components. Thirdly, we suggest a conceptual framework for evaluating the synergies and tradeoffs of bioenergy with other bioeconomic and economic activities along the Nexus. Follow-up empirical research at household and community levels in several developing countries will be based on this framework. Finally, a discussion on the conceptual framework is enriched by insights on the relevant actors, the tools and mechanisms specific to these actors for catalyzing innovations in the bioenergy for development.

Organic agriculture in Bhutan: potential and challenges

The Government of Bhutan, a poor rugged mountainous kingdom in the Himalayas, aims to convert the whole agricultural area to Organic Agriculture (OA) by 2020 in an effort to provoke a substantial increase of productivity and farmers income while preserving the environment. Currently less than 10 % of the agricultural area of Bhutan is in OA production. We analysed the assumptions of the Bhutanese Government cited above from an agronomic perspective. According to our estimates, farmer incomes after conversion will increase only if organic crops will out-yield conventional crops or if farmers can realize higher market prices. Organic yields may partly increase beyond current productivity but may not become as high as in systems using agrochemicals. Under these premises, higher farmer incomes after mass conversion are not likely. The current low agricultural productivity is mainly a result of low soil fertility combined with other system-independent factors such as inadequate input supply, e.g. low quality seeds, lack of techniques and knowledge, inefficient management, labour shortage and poor infrastructure. These problems need to be tackled with integrated approaches, which should include organic management practices such as growing fodder legumes. Integrating more strategies of OA into Bhutanese agriculture is expected to have positive ecological effects. System comparisons between conventional and organic production require more empirical data on the agronomic and economic performances, which are yet to be generated in Bhutan. In addition to trade policies, market and infrastructure development, the organic sector will benefit from a well-resourced Centre of Excellence to focus on research and knowledge transfer.

Growth behavior ofPhyllostachys nigra var.henonis (Bambusoideae) in Central China

In the Shennongjia National Nature Reserve of Central China, the vegetative growth behavior of henon bamboo (Phyllostachys nigra var.henonis (Mitford) Stapf. ex Rendle) was studied from shoot recruitment to culm establishment. In May, bamboo shoots emerging from the ground achieved an average density of 2.7 shoots m−2 during the sprouting phase of 16 days. However, about 32% of the new shoots died back before maturity. Insect damage, withering death and rodent predation were responsible for 57%, 29% and 14% of the total shoot mortality, respectively. From May to June, the shoots attained 400±23 cm during the height growth phase of 34 days, with a daily rate varying from 1 to 56 cm. All branches and leaves unfolded during the branch spreading phase from June to August. Shoot production was positively related to the density of standing culms, but negatively to both coverage and height of herb layers.

A participatory framework to assess multifunctional land-use systems with multicriteria and multivariate analyses: A case study on agrobiodiversity of agroforestry systems in Tomé Açú, Brazil

Abstract In a participatory framework, the multifunctionality of agroforestry systems was assessed by applying multicriteria and multivariate analyses to identify ecological, agronomic and administrative proxies and integrate these into factors, and evaluate their effects on system performance. The assessment framework was tested in 70 farms in the municipality of Tomé-Açú in the Brazilian Amazon, an area well known for its long-standing practice of agroforestry. The overall goal was to identify management decisions that ensure sustainable production of goods together with the provision of ecosystem services, with special emphasis on agrobiodiversity. Three groups of farmers were considered based on their period of settlement, property size, technological know-how, organization and access to the market. The results show that the determinant factors of multifunctional farming are the farmers’ technical qualification, good adaptability, environmental commitment and the search for financial profitability. However, the optimization of these factors leads to trade-offs such as a decrease in biomass and woody species diversity and the decline of by-product production. By considering stakeholders’ opinions and being adaptable to various demands, the proposed framework enhances the legitimacy of the results, and supports both the assessment of complex issues and decision-making.