Carbon sequestration and biodiversity of re-growing miombo woodlands in Mozambique

Land management in tropical woodlands is being used to sequester carbon (C), alleviate poverty and protect biodiversity, among other benefits. Our objective was to determine how slash-and-burn agriculture affected vegetation and soil C stocks and biodiversity on an area of miombo woodland in Mozambique, and how C stocks and biodiversity responded once agriculture was abandoned. We sampled twenty-eight 0.125 ha plots that had previously been cleared for subsistence agriculture and had been left to re-grow for 2 to ∼25 years, and fourteen 0.25 ha plots of protected woodlands, recording stem diameter distributions and species, collecting wood for density determination, and soil from 0 to 0.3 m for determination of %C and bulk density. Clearance for agriculture reduced stem wood C stocks by 19.0 t C ha⁻¹. There were significant relationships between period of re-growth and basal area, stem numbers and stem biomass. During re-growth, wood C stocks accumulated at 0.7 t C ha⁻¹ year⁻¹. There was no significant difference in stem C stocks on woodlands and on abandoned farmland 20–30 years old. Soil C stocks in the top 0.3 m on abandoned land had a narrower range (21–74 t C ha⁻¹) than stocks in woodland soils (18–140 t C ha⁻¹). There was no discernible increase in soil C stocks with period of re-growth, suggesting that the rate of accumulation of organic matter in these soils was very slow. The re-growing plots did not contain the defining miombo species, and total stem numbers were significantly greater than in woodland plots, but species richness and diversity were similar in older abandonments and miombo woodlands. Wood C stocks on abandoned farmland were capable of recovery within 2–3 decades, but soil C stocks did not change on this time-scale. Woodland soils were capable of storing >100 t C ha⁻¹, whereas no soil on a re-growing area exceeded 74 t C ha⁻¹, so there is a potential for C sequestration in soils on abandoned farmland. Management should focus on identifying C-rich soils, conserving remaining woodlands to protect soil C and preserve defining miombo species, and on investigating whether fire control on recovering woodland can stimulate accumulation of soil C and greater tree biomass, and restore defining miombo species.     

Dispersal potentials determine responses of woody plant species richness to environmental factors in fragmented Mediterranean landscapes

While maximizing plant species richness continues to be central in the design, conservation and reforestation action plans, plant life histories are receiving increasing attention in assessments for the conservation of biodiversity in fragmented landscapes. We investigated the determinants of woody plant species (trees, shrubs and climbers) richness in the forest patches of the Guadalquivir river valley, a Mediterranean agricultural landscape with ∼1% forest cover. We analyzed three species richness variables, total, and those corresponding to species with short-distance (ballistic, barochorous, myrmecochorous and short-distance anemochorous) and long-distance (anemochorous, endozochorous, exozoochorous, hydrochorous and dyszoochorous) dispersal systems, which significantly characterize earlier and late successional stages, respectively. We selected eleven predictor variables related to habitat structure (patch area, shape, distances to the nearest patch and reserve, and general isolation), physical environment (temperature, precipitation, elevation, and lithological heterogeneity), and anthropogenic influences (disturbance and proportion of old-growth forest). We used ordinary-least-squares multiple regression (OLS) and the Akaike's information criterion (corrected for spatial autocorrelation) and derived indices to generate parsimonious models including multiple predictors. These analyses indicated that plant species richness increase primarily along with increasing patch area and decreasing disturbance, but also detected secondary effects of other factors when dispersal was considered. While the number of species with potential long-distance dispersal tended to increase in more isolated patches of areas with greater precipitation and lithological heterogeneity (e.g. highlands at the valley edges), the number of species with short-distance dispersal increased towards drier and less lithologically complex zones with shorter between-patch distances (e.g. central lowlands). Beyond emphasizing the need to consider dispersal in fragmentation studies, our results show that woody plant species richness would be favoured by actions that increase patch area and reduce anthropogenic disturbances particularly in lowland forests.     

Secondary succession in a fragmented Atlantic Forest landscape: evidence of structural and diversity convergence along a chronosequence

Changes in physiognomy, species composition and structure, and dispersal mechanisms of canopy and subcanopy plant assemblages were investigated along a chronosequence of three ages: 12, 20, and 50+ years old (=old-growth), three replications in each, in an Atlantic Forest landscape in Northeastern Brazil. Our objective was to investigate whether there is floristic and structural convergence along secondary succession. There were significant differences between secondary and old-growth forests in density and basal area only for the subcanopy. Differences in density between forest ages were noted when the assemblage was analyzed per diameter and height classes. Richness of canopy species of both secondary ages differed from those of old-growth forests. Some dominant species in the canopy of secondary forests showed a significant decrease in density with increasing age, which indicates an ongoing process of floristic changes. The low level of shared species between secondary and old-growth forests supports the idea that species composition is one of the last components to recover during successional process. Zoochory was the most important dispersal guild in species percentage and number, irrespective of stand age. Although regenerating areas can take alternative pathways, our results indicate that secondary Atlantic Forest sites have a high potential for natural regeneration. This recovery is recorded as a physiognomic convergence of the canopy layer in as little as 12 years, and progressive introductions of later successional species into the plant assemblage that lead to convergence in terms of the diversity and richness of the subcanopy and of dispersal guilds just 20 years after abandonment.     

Managing small remnants of native forest to increase biodiversity within plantation landscapes in the south west of Western Australia

Recent expansion of industrial-scale plantations into agricultural areas in Australia has the potential to assist biodiversity conservation by rehabilitating ecosystems at the landscape scale and reducing edge effects, isolation and disturbance within remnants of native vegetation. However, the efficient management of remnants for biodiversity within a plantation estate requires knowledge of both the causes and the consequences of remnant degradation. With this in mind, we examined key ecosystem features and processes relating to soil chemistry, decomposition, native tree health and regeneration and vertebrate abundance, within small forest remnants (1-4 ha) embedded within Eucalyptus globulus plantations in south west Western Australia. Soil nutrient enrichment was significantly associated with a scale of vegetation modification in order from: (1) intact forest, (2) remnants with native understorey (UDN), (3) remnants with exotic understorey (UDE), (4) plantation and (5) pasture. We propose that, in this region, UDE remnants will often remain in a degraded state even after plantation establishment and the cessation of stock grazing. This is due, in part, to more rapid rates of nutrient turnover sustaining higher nutrient availability in the soil following the replacement of ligneous understorey plants with annual ones. Cotton strips placed in surface soils were often disintegrated in UDE remnants and largely intact in UDN remnants, indicating that decomposition was accelerated in the former. Continued tree decline and regeneration failure within UDE remnants will also reinforce the UDE condition. There was less canopy seed set and little or no seedling establishment in UDE remnants compared to UDN remnants. Therefore, management interventions to assist native tree regeneration in UDE remnants are needed. Fauna trapping highlighted the desirability of retaining, and preferably restoring, small remnants in plantations. Small native mammals were found exclusively in remnants and fewer introduced Mus musculus were present in UDN remnants. Higher numbers of native lizards were found in UDN remnants, but this result was not significant (marginally).     

An ecosystem approach to biodiversity effects: Carbon pools in a tropical tree plantation

This paper presents a synthesis of experiments conducted in a tropical tree plantation established in 2001 and consisting of 22 plots of 45 m × 45 m with either one, three or six native tree species. We examined the changes in carbon (C) pools (trees, herbaceous vegetation, litter, coarse woody debris (CWD), and mineral topsoil at 0-10 cm depth) and fluxes (decomposition of CWD and litter, as well as soil respiration) both through time and among diversity levels. Between 2001 and 2009 the aboveground C pools increased, driven by trees. Across diversity levels, the mean observed aboveground C pool was 7.9 ± 2.5 Mg ha⁻¹ in 2006 and 20.4 ± 7.4 Mg ha⁻¹ in 2009, a 158% increase. There was no significant diversity effect on the observed aboveground C pool, but we found a significant decrease in the topsoil C pool, with a mean value of 34.5 ± 2.4 Mg ha⁻¹ in 2001 and of 25.7 ± 5.7 Mg ha⁻¹ in 2009 (F_1,36 = 52.12, p < 0.001). Assuming that the biomass C pool in 2001 was negligible (<1 Mg ha⁻¹), then the plantation gained in C, on average, ∼20 and lost ∼9 Mg ha⁻¹ in biomass and soil respectively, for an overall gain of ∼11 Mg ha⁻¹ over 8 years. Across the entire data set, we uncovered significant effects of diversity on CWD decomposition (diversity: F_2,393 = 15.93, p < 0.001) and soil respiration (monocultures vs mixtures: t = 15.35, df = 11, p < 0.05) and a marginally significant time × diversity interaction on the loss of total C from the mineral topsoil pool (see above). Monthly CWD decomposition was significantly faster in monocultures (35.0 ± 24.1%) compared with triplets (31.3 ± 21.0%) and six-species mixtures (31.9 ± 26.8%), while soil respiration was higher in monocultures than in mixtures (t = 15.35, df = 11, p < 0.001). Path analyses showed that, as diversity increases, the links among the C pools and fluxes strengthen significantly. Our results demonstrate that tree diversity influences the processes governing the changes in C pools and fluxes following establishment of a tree plantation on a former pasture. We conclude that the choice of tree mixtures for afforestation in the tropics can have a marked influence on C pools and dynamics.     

Models for estimation of tree volume in the miombo woodlands of Tanzania

Volume of trees is an important parameter in forest management, but only volume models with limited geographical and tree size coverage have previously been developed for Tanzanian miombo woodlands. This study developed models for estimating total, merchantable stem and branches volume applicable for the entire miombo woodlands of Tanzania. We used data from 158 destructively sampled trees, including 55 tree species collected from wide geographical and biophysical ranges. We developed general and site-specific models with diameter at breast height only as the independent variable, together with models with both diameter at breast height and tree height. Leave-one-out cross-validation was used to evaluate the models. The total tree volume models that included diameter at breast height and tree height had appropriate predictive capabilities with relative root mean square errors (RMSE_r) ranging from 30.5% to 47.6%. The RMSE_r for total tree volume models with diameter at breast height only ranged from 39.9% to 48.0%. The site-specific models had slightly lower RMSEr values relative to the general models. The relative mean prediction error of the general total tree volume model with diameter at breast height and tree height was lower (0.6%) than those of the previously developed models (?30.7% to 31.2%). Based on the evaluations, we recommend the general total tree models to be applied over a wide range of geographical and biophysical conditions in Tanzania.     

Replacing coniferous monocultures with mixed-species production stands: An assessment of the potential benefits for forest biodiversity in northern Europe

Conifer dominated plantations in central and northern Europe are associated with relatively low ecological values, and in some cases, may be vulnerable to disturbances caused by anthropogenic climate change. This has prompted the consideration of alternative tree species compositions for use in production forestry in this region. Here we evaluate the likely biodiversity costs and benefits of supplanting Norway spruce (Picea abies) monocultures with polycultures of spruce and birch (Betula spp.) in southern Sweden. This polyculture alternative has previously been evaluated in terms of economic, recreational, and silvicultural benefits. By also assessing the ecological implications we fill a gap in our understanding of the range of socio-ecological benefits that can be achieved from a single polyculture alternative. We project likely broad scale changes to species richness and abundance within production stands for five taxonomic groups including ground vegetation, tree-living bryophytes, lichens, saproxylic beetles, and birds. Our research leads us to three key findings. First, the replacement of spruce monocultures with spruce–birch polycultures in the managed forest landscapes of southern Sweden can be expected to result in an increase in biological diversity for most but not all taxa assessed, but it is unlikely to improve conditions for many red-listed forest species. Second, modification of other aspects of forest management (i.e. rotation length, dead wood and green tree retention, thinning regimes) is likely to contribute to further biodiversity gains using spruce–birch polycultures than spruce monocultures. Third, the paucity of empirical research which directly compares the biodiversity of different types of managed production stands, limits the extent to which policy relevant conclusions can be extracted from the scientific literature. We discuss the wider implications of our findings, which indicate that some climate change adaptation strategies, such as risk-spreading, can be readily integrated with the economic, environmental and social goals of multi-use forestry.     

Managing woodlands for income maximisation in western Queensland,Australia: clearing for grazing versus timber production

Queensland, Australia, has a proud pastoral history; however, the private and social benefits of continued woodland clearing for pasture development are unlikely to be as pronounced as they had been in the past. The environmental benefits of tree retention in arid regions of the State are now better appreciated and market opportunities have arisen for the unique timbers of western Queensland. A financial model is developed to facilitate a comparison of the private profitability of small-scale timber production from remnant Acacia woodlands against clearing for pasture development in the Mulga Lands and Desert Uplands bioregions of western Queensland. Four small-scale timber production scenarios, which differ in target markets and the extent of processing (value-adding), are explored within the model. Each scenario is examined for the cases where property rights to the timber are vested with the timber processor, and where royalties are payable. For both cases of resource ownership, at least one scenario generates positive returns from timber production, and exceeds the net farm income per hectare for an average grazing property in the study regions over the period 1989–1990 to 2000–2001. The net present value per hectare of selectively harvesting and processing high-value clearwood from remnant western Queensland woodlands is found to be greater than clearing for grazing.     

Homegarden agroforestry systems: an intermediary for biodiversity conservation in Bangladesh

Biodiversity conservation is one of the important ecosystem services that has been negatively impacted by anthropogenic activities. Natural forests (NF) harbor some of the highest species diversity around the world. However, deforestation and degradation have resulted in reduced forest land cover and loss of diversity. Homegarden agroforestry (AF) systems have been proven to be an intermediary for biodiversity conservation. In this study, we evaluate the effectiveness of home garden AF practices to conserve tree species diversity in Bangladesh and compare them with tree species diversity in NF. A total of nine locations were selected for this synthesis from published literature which comprised of five AF sites and four NFs. Shannon?CWeiner Diversity Index (H) was similar for home-garden AF (3.50) and NF (2.99), with no statistical difference between them. Based on non-metric multi-dimensional scaling (NMDS) ordination analysis, the AF and NF plots showed distinct separation. However, Bray?CCurtis dissimilarity index ranged from 0.95 to 0.70 indicating nearly no overlap in species composition to significant overlap between AF and NF. Based on our results, we conclude that AF can serve as an important ecological tool in conserving tree species diversity, particularly on landscapes where NF fragments represent only a small fraction of the total land area. Creating and maintaining AF habitats in such human dominated landscapes should be part of the biodiversity conservation strategy.     

慈溪市山地森林景观多样性分析

根据景观生态学原理,结合慈溪市2007年森林资源规划设计调查资料,在地理信息系统（GIS）支持下,对慈溪市山地森林景观多样性进行了定性和定量分析。结果表明,灌木林、竹林、其它经济林等破碎化程度较高,而松林、阔叶林和具有规模经营的杨梅斑块密度较大,分离度也最小。若进一步加强低效林改造以及无立木林地的生态恢复,森林景观多样性将进一步增加,也有利于该区域森林进一步向良性方向发展。     

Re-inventing forestry expertise: Strategies for coping with biodiversity protection in Finland

Tackling biodiversity loss requires new forms of expertise in forestry. Drawing on a case study in Finland, the paper analyses how professional foresters are invited to protect the heterogeneity of forest ecosystems while they simultaneously work to homogenise these habitats for improved productivity. To understand how formerly irrelevant biological knowledge, and related skills and expertise gain credibility in forestry decision-making in such a complex policy context, the paper adopts a two-fold theoretical approach. On one hand, it focuses on the tools and techniques which redirect expert practice, introducing new rationalities, roles and routines for professional foresters. On the other hand, it seeks to view foresters as complex sociological actors who reinvent themselves as biodiversity experts by strategically mobilising various kinds of resources to negotiate their role and status as experts. This two-fold analysis addresses how the status of biological knowledge is determined by the tension between formally configured expert rationalities and expert identities and roles mobilised through informal interactions. Three expert strategies in engaging with biodiversity are identified based on the personal histories, motivations and identities of the foresters: the ambassador, navigator and bolshie. Through these strategies professional foresters interact with each other and with landowners while implementing biodiversity policies, hence influencing the policy outcomes.     

Clearance of understory in urban woodlands: Assessing impact on bird abundance and diversity

Clearance of understory to enhance the recreational value of the forest is common in urban woodlands. Open forests are generally perceived as safe and pleasant, but clearance is likely to be negative for woodland birds as the shrub layer is important for foraging and protection. In this 3-year experiment with a before after control impact (BACI) design, the effects from understory clearance on woodland bird abundance and diversity in five suburban broadleaved forests in south-western Sweden were studied. Understory clearance was either made in regular patches, with 50% removal of understory, or as “Complete” (90%) removal. Adjacent stands of equal size were left unmanaged as controls. Woodland birds and understory vegetation were surveyed before and after the management. The total density of breeding forest birds decreased in the plots with “Complete” removal of the understory compared to plots with “Patchy” clearance. “Patchy” clearance had no significant effect on bird density. Bird diversity was not affected by the management. Woodland birds are highly valued animals in urban green areas and the impact on bird fauna should therefore be taken into consideration in the development of management plans for urban woodlands. The present study has demonstrated that clearance of understory can have negative effects on bird abundance if carried out over large areas. Clearance in patches was not found to have negative effects on bird abundance and can promote recreational values by increasing visibility and structural variation of the forest.     

The ecology and management of the Miombo woodlands for sustainable livelihoods in southern Africa: the case for non-timber forest products

There is new and increasing emphasis on the contribution of non-timber forest products (NTFPs) to improving the livelihoods of rural communities and therefore the need for sustainable management of forest ecosystems of the Miombo woodlands to ensure the continued availability of these NTFPs. This paper examines and reviews some of the work that has been done in the Miombo ecoregion on the ecology, utilisation and management of the Miombo woodlands. The review points to the richness of the Miombo regions' plant species, with an estimated 8 500 species of higher plants, of which over 54% are endemic. The review also highlights the response of the Miombo ecosystem to fire and other anthropogenic processes and the lack of wide-scale adoption or implementation of the major research findings. The review shows that there is a wide range of NTFPs that significantly contribute to the total household income in forest areas and to the national economies through provision of opportunities for small-scale trade especially in the rural areas. However, there is a concern that commercialisation usually results in overexploitation of the resource by the outsiders who become the major players. It is suggested from the review that the lack of capacity by national institutions to manage Miombo woodland resources could be addressed by using participatory approaches to natural resource management. It is also proposed that for sustainable use and management of NTFPs in the Miombo region, research should focus on issues that specifically address NTFPs. In order to facilitate commercialisation and benefit the economically weak, policies that incorporate postharvesting technical assistance and access to information on markets, technology and microcredit should be developed and promoted.     

Ecological thresholds in herb communities for the management of suburban fragmented forests

Fragmentation is a major cause of biodiversity loss. The relationship between fragmentation and biodiversity might be non-linear, due to the presence of ecological thresholds; however, the application of the threshold concept on the conservation of herb biodiversity has received limited attention. We assessed the relationship between a pool of woodland indicators and features of forest fragments (area, isolation, shape), and we evaluated whether ecological thresholds might provide guidelines for conservation. We performed our study in a human dominated area of northern Italy. In order to obtain a group of floristic indicators, we chose perennial herbs characteristic of the phytosociological syntaxa Fagetalia sylvaticae, Carpinion betuli and Erythronio-Carpinion, with suitable Landolt L and H index, obtained from previous relevés in reference and high-quality forests. Subsequently, we analyzed the relationship between richness of indicators and patch features recorded in a highly fragmented landscape. Generalized linear models showed that the number of forest indicators was positively related to fragment size and connectivity. Generalized Additive Models showed that the relationship between indicator richness and fragment size was non-linear, with the presence of two thresholds. The number of forest indicators increased until 35–40 ha; above this size the richness remained constant. Fragments above this threshold should be the target of conservation. Furthermore, the relationship between area and number of indicators was less steep in patches smaller than 1–1.5 ha. Patches between these two thresholds can be optimal targets of management actions, as small size increases can greatly improve their value for biodiversity. The identification of two thresholds in the relationship between patch area and indicators suggests an abrupt response to changing landscape features and provide quantitative targets for conservation.     

Community-Based Forest Enterprises in Nepal: An Analysis of Their Role in Increasing Income Benefits to the Poor

This paper examines the effective practices and constraints of community-based forest management enterprises (CBFEs) in Nepal in providing income benefits to the poor. The tenure reform clarity and strengthening of tenure rights at community level through various CBFM programs in Nepal in the last few decades has enhanced opportunities for the rural people to benefit from forest-based enterprises. However, a key concerns as these programs have advanced over the years has been whether the poor benefit from them given their high dependence on the forests. To examine this question, 28 CBFE from Nepal’s mid-hills and mountain districts were selected purposively from among forest user groups (FUGs) engaged in income-generating activities, varying in their size of membership, use of forest products and stage of growth. These CBFEs have been broadly categorised into FUGs, networks, cooperatives and companies. The contribution from enterprises to the household economy was found to be greatest from companies, followed by cooperatives and then networks. The effective practices of the CBFEs in increasing income benefits were found to include representation of the poor and marginalized groups in executive committees in the FUGs-based enterprises, targeted employment of the poorest in the collection of non-timber forest products and in processing units in networks, and enabling the poor to own share capital in cooperatives and companies. The common constraint across all these categories was found to be lack of adequate capital to sustain the enterprises without external support.The specific constraints were small membership and land size among FUGs, lack of legal recognition of networks, lack of management skills and member discipline for cooperatives, and lack of raw materials and marketing capacity for companies. The paper also discusses: the importance of further policy support to formalize forest user groups into networks, cooperatives and private companies; value addition to forest products; and capacity building for CBFEs, government line agencies and business services providers.     

Management of forested landscapes in mountain areas: an ecosystem-based approach

The goal of this paper is to show how an ecosystem-based approach can contribute simultaneously to a multipurpose use of forest resources in mountain areas, and to the maintenance of the quality of the forests and forested landscapes producing the resources. An ecosystem-based approach in managing forest resources in mountain areas is considered as essential. Its principles, methods and instruments are introduced and illustrated with examples. The accent is put on the importance of the landscape (ecocomplex) level, the integration of ecological, economic and social considerations, and the use of multicriteria decision aid techniques.     

Improving landscape connectivity in forest districts: A two-stage process for prioritizing agricultural patches for reforestation

Connectivity is a key concern in natural resource planning. Many studies have focused on the development of methods, tools and indices for the assessment of both components of connectivity: structural and functional. In particular, approaches based on graph theory principles have been recently proposed and are being increasingly applied to guide landscape connectivity conservation. However, forest planners and managers still need effective and operational methodologies to detect those landscapes where connectivity should be treated as a particularly critical conservation concern. In addition, in the Mediterranean, as in other parts of the world, socioeconomic changes in the last decades have driven the abandonment of many formerly cultivated lands. This poses both a challenge and an opportunity for managers intending to restore ecological connectivity in forested areas. In this context, setting adequate priorities for the reforestation of agricultural lands is of outmost importance. Here we show how a two-stage hierarchical methodology based on network analysis can be used to meet these needs. In particular, we apply a graph metric based on the measurement of habitat availability at the landscape scale (the Integral Index of Connectivity) to two Mediterranean forest districts in Spain with different management objectives and environmental heterogeneity. First, we identify those landscapes where efforts to improve forest connectivity should be concentrated. In a second stage, we prioritize within those landscapes the individual patches of agricultural lands that, being available for a potential reforestation program, would contribute most to uphold connectivity and ecological flows at wide spatial scales. We show how the extent of the agricultural patches is not strictly related to the contribution to connectivity they would provide if reforested, and how the results of such analysis vary with species traits (dispersal capabilities). We discuss the suitability of the proposed approach for forest landscape planning purposes and conclude that it can provide a useful diagnosis and helpful guidelines for the development of efficient reforestation programs that might be applied in a variety of situations for improving the ecological coherence of forest landscapes.