Assessment on the Suitability of Planting Non-Native Peatlands Species Falcataria moluccana (Miq.) Barneby & Grimes in Rewetted Peatlands

Sengon (Falcataria moluccana), a fast-growing timber tree that naturally grows on mineral soils, is currently promoted in peatlands. This study aimed to (1) experimentally test the response of sengon seedlings in waterlogged conditions in the nursery; (2) describe and analyze the biophysical condition of a sengon plantation and its growth; (3) describe sengon farm practices on peatlands; and (4) identify key actor’s perception on planting sengon on peatlands. This study combined an experiment in nursery, field measurements, and key-informant interviews. The nursery experiment showed that peat soil affected seedling’s growth: survival rates decreased by 25–33% after 3 months of inundation. Sengon growth at age 1–5-years-old in peat soil was slower than that on mineral soils. Sengon growth in peatland was influenced by peat depth and peat maturity. Sengon plantation in Central Kalimantan was driven by market availability and industrial wood demand. Fourty-three percent of respondents thought sengon does not grow well in peat soils, but 57% of respondents thought that additional soil treatment will enhance site suitability. Based on key-informants’ experience, 64% disagree with sengon development in peatlands. Our study provides evidence that sengon is predominantly not suitable to be planted on peatlands. Therefore, cautions need to be taken when planting sengon on peatland areas

Tree cover transitions and food security in Southeast Asia

Trees are sources of food, especially fruits, critical for healthy diets. Trees also modify microclimate, water and nutrient flows for crops and livestock, and are a source of income, allowing forest-edge communities to be food-sufficient through trade without cutting down forests. Opportunities for ecological intensification, utilizing trees in agricultural landscapes, vary along stages of a tree cover transition of forest alteration and deforestation followed by agroforestation. The nonlinear forest transition curve can provide both a theory of change (similarity of processes) and a theory of place (configuration of state variables). We reviewed local perspectives on food security for four configurations of the forest and landscape transition in Southeast Asia, with local human population densities ranging from less than 10 to 900 km-2 to explore how current generic ‘theories of change’ on how to achieve global food security need more explicit ‘theories of place’ that take such differences into account

Constraints and opportunities for tree diversity management along the forest transition curve to achieve multifunctional agriculture

On-farm tree diversity patterns result from a social-ecological process shaped by different actors. Farmer preferences, tree-site matching, seed dispersal, tree domestication and delivery via nurseries all play important roles in forming these patterns. As part of a wider interest in tree cover transition curves that link agroforestation stages of landscapes to a preceding deforestation process, we here focus on ‘tree diversity transition curves’ i. as a conceptual framework to understand current processes and how shifts in drivers affect tree diversity and ii. to help identify constraints and opportunities for interventions. We provide some examples of current research efforts and make suggestions for databases and analyzes that are required to improve our understanding of tree diversity transitions. We explore drivers, consequences and entry points for tree diversity management to achieve multifunctional agriculture

Tree cover transitions and food security in Southeast Asia

Trees are sources of food, especially fruits, critical for healthy diets. Trees also modify microclimate, water and nutrient flows for crops and livestock, and are a source of income, allowing forest-edge communities to be food-sufficient through trade without cutting down forests. Opportunities for ecological intensification, utilizing trees in agricultural landscapes, vary along stages of a tree cover transition of forest alteration and deforestation followed by agroforestation. The nonlinear forest transition curve can provide both a theory of change (similarity of processes) and a theory of place (configuration of state variables). We reviewed local perspectives on food security for four configurations of the forest and landscape transition in Southeast Asia, with local human population densities ranging from less than 10 to 900 km-2 to explore how current generic ‘theories of change’ on how to achieve global food security need more explicit ‘theories of place’ that take such differences into account

Wood Density and Dispersal Modes of Trees Regenerating in Disturbed Forests and Agroforests in Indonesia

Natural regeneration depends on surviving propagules in the soil, seed sources from a surrounding landscape mosaic, and dispersal agents. We compiled and analyzed four sets of case studies varying in degree of disturbance, for secondary forests recovering from logging, fire, and conversion to agroforest in Sumatra or Kalimantan (Indonesia) on mineral and peat soils. Data on tree species diversity, wood density frequency distribution (indicative of successional status, databases with over 6000 species exist), and dispersal modes were compared with those for less disturbed comparator forests for the same landscapes. Undisturbed lowland dipterocarp forest in Kalimantan had close to 200 species of trees of more than 10 cm diameter at a 1 ha sample scale (and 450 at a 10-ha scale), regulation-based logging had little impact. Still, after the repeated fire a sample area of 2 ha was needed to reach the same species numbers. After forest conversion to low-management-intensity rubber agroforest, 50 tree species were found at a ha scale and close to 100 species in 3 ha. Peat swamp forest in Kalimantan and the Sumatra forest samples had close to 100 species in 1 to 2 ha. The Kalimantan forest after a repeated fire had a markedly higher fraction of low-wood-density trees (40%), but otherwise, all forests sampled were similar in overall wood density profiles. Logged-over forest managed by community (village forest) and rubber agroforest in Sumatra contained larger fractions of heavy-wood-density trees (including rubber). The majority of trees (50-70%) had birds, bats, and primates as dispersal agents in all sites. Logged-over forests on mineral soil had higher fractions of autochorous species (15%) compared to other sites. Anemochorous (wind-dispersed) species were most common (20%) in undisturbed lowland Dipterocarp forest and peat swamp forest recovering after logging and fire. Comparison between secondary forests and agroforests showed the influence of farmer selection regarding what is allowed to grow beyond the pole stage. Wood density and seed dispersal profile can be used as degradation indicators of species assemblages across various disturbance levels and types. They can also reflect the habitat quality of the surrounding forming restoration options

Mud, muddle and models in the knowledge value-chain to action on tropical peatland conservation

Tropical peatlands are known not only for their high, area-based, carbon emissions in response to land-use change but also as hot spots of debate about associated data uncertainties. Perspectives are still evolving on factors underlying the variability and uncertainty. Debate includes the ways of reducing emissions through rewetting, reforestation and agroforestry. A knowledge value-chain that is long and complex links (a) fundamental understanding of peat and peatland processes leading to sciencebased quantification and default values, (b) willingness and (c) ability to act towards emission reduction, and ultimately (d) to local, national and global actions that effectively provide rules, incentives and motivation to conserve peat and reduce emissions. We discuss this value chain, its stakeholders and issues that still remain partially unresolved.We conclude that, to shorten the denial and conspiracy-theory stages of debate that otherwise slow down steps B and C, networks of international and national scientists have to be involved at the early stage of identifying policysensitive environmental issues. Models span part of the knowledge value-chain but transition of analysis units requires specific attention, from soil volumes through area and commodity flows to opportunities for reductions. While drainage of peatlands triggers landscape-scale increases in emissions, factors beyond drainage depth, including nutrient supply, may have a major influence on decomposition rates. Attempts to disentangle the contributions of plant and peat-based respiration in surface flux measurements involve assumptions that cannot be easily verified in comparisons between land uses. With progress on A leading to new internationally accepted defaults and with resistance on step B reduced, the reality of C and lack of working solutions for D is currently constraining further progress

Microstructural effects in face-centered-cubic alloys after small charge explosions

Effects on metal targets after an explosion include the following: fracture, plastic deformation, surface modifications, and microstructural crystallographic alterations with ensuing mechanical properties changes. In the case of small charge explosions, macroscopic effects are restricted to small charge-to-target distances, whereas crystal alterations can still be observed at moderate distances. Microstructural variations, induced on gold-alloy disk samples, as compared to previous results on AISI 304Cu steel samples, are illustrated. The samples were subjected to blast-wave overpressures in the range of 0.5 to 195 MPa. Minimum distances and peak pressures, which could still yield observable alterations, were especially investigated. Blast-related microstructural features were observed on the explosion-exposed surface and on perpendicular cross sections. Analyses using X-ray diffraction (XRD) were performed to identify modifications of phase, texture, dislocation density, and frequency of mechanical twins, before and after the explosions. Optical metallography (OM) and scanning electron microscopy (SEM) observations evidenced partial surface melting, zones with recrystallization phenomena, and crystal plastic deformation marks. The latter marks are attributed to mechanical twinning in the stainless steel and to cross-slip (prevalent) and mechanical twinning (possibly) in the gold allo