Tree crown mapping in managed woodlands (parklands) of semi-arid West Africa using WorldView-2 imagery and geographic object based image analysis.

Detailed information on tree cover structure is critical for research and monitoring programs targeting African woodlands, including agroforestry parklands. High spatial resolution satellite imagery represents a potentially effective alternative to field-based surveys, but requires the development of accurate methods to automate information extraction. This study presents a method for tree crown mapping based on Geographic Object Based Image Analysis (GEOBIA) that use spectral and geometric information to detect and delineate individual tree crowns and crown clusters. The method was implemented on a WorldView-2 image acquired over the parklands of Saponé, Burkina Faso, and rigorously evaluated against field reference data. The overall detection rate was 85.4% for individual tree crowns and crown clusters, with lower accuracies in areas with high tree density and dense understory vegetation. The overall delineation error (expressed as the difference between area of delineated object and crown area measured in the field) was 45.6% for individual tree crowns and 61.5% for crown clusters. Delineation accuracies were higher for medium (35-100 m(2)) and large (≥100 m(2)) trees compared to small (<35 m(2)) trees. The results indicate potential of GEOBIA and WorldView-2 imagery for tree crown mapping in parkland landscapes and similar woodland areas.

The Chinese Grain for Green Programme: assessing the carbon sequestered via land reform.

The Grain for Green Programme (GGP) was launched in China in 1999 to control erosion and increase vegetation cover. Budgeted at USD 40 billion, GGP has converted over 20 million hectares of cropland and barren land into primarily tree-based plantations. Although GGP includes energy forests, only a negligible part (0.6%) is planted as such, most of the land (78%) being converted for protection. Future use of these plantations is unclear and an energy substitution hypothesis is valid. We estimate the overall carbon sequestration via GGP using official statistics and three approaches, based on i) net primary production, ii) IPCC's greenhouse gas inventory guidelines, and iii) mean annual increment. We highlight uncertainties associated with GGP and the estimates. Results indicate that crop- and barren-land conversion sequestered 222-468 Mt of carbon over GGP's first ten years, the IPCC approach yielding the highest estimate and the other two approaches yielding similar but lower estimates (approximately 250 Mt of carbon). The carbon stock in these plantation systems yields a mean of 12.3 t of carbon per hectare. Assessment uncertainties concern the use of growth curves not designed for particular species and locations, actual plantation survival rates, and discrepancies in GGP figures (e.g., area, type, and survival rate) at different authority levels (from national to local). The carbon sequestered in above- and below-ground biomass from GGP represents 14% (based on the median of the three approaches) of China's yearly (2009) carbon dioxide emissions from fossil fuel use and cement production.

Homegardens as a multi-functional land-use strategy in Sri Lanka with focus on carbon sequestration.

This paper explores the concept of homegardens and their potential functions as strategic elements in land-use planning, and adaptation and mitigation to climate change in Sri Lanka. The ancient and locally adapted agroforestry system of homegardens is presently estimated to occupy nearly 15 % of the land area in Sri Lanka and is described in the scientific literature to offer several ecosystem services to its users; such as climate regulation, protection against natural hazards, enhanced land productivity and biological diversity, increased crop diversity and food security for rural poor and hence reduced vulnerability to climate change. Our results, based on a limited sample size, indicate that the homegardens also store significant amount of carbon, with above ground biomass carbon stocks in dry zone homegardens (n = 8) ranging from 10 to 55 megagrams of carbon per hectare (Mg C ha(-1)) with a mean value of 35 Mg C ha(-1), whereas carbon stocks in wet zone homegardens (n = 4) range from 48 to 145 Mg C ha(-1) with a mean value of 87 Mg C ha(-1). This implies that homegardens may contain a significant fraction of the total above ground biomass carbon stock in the terrestrial system in Sri Lanka, and from our estimates its share has increased from almost one-sixth in 1992 to nearly one-fifth in 2010. In the light of current discussions on reducing emissions from deforestation and forest degradation (REDD+), the concept of homegardens in Sri Lanka provides interesting aspects to the debate and future research in terms of forest definitions, setting reference levels, and general sustainability.

REDD+ readiness implications for Sri Lanka in terms of reducing deforestation.

Any system to compensate countries for reduced emissions from deforestation and forest degradation (REDD+) requires a historical reference level against which future performance can be measured. Here we examine the possibilities Sri Lanka, a small forest country with limited data on forest carbon stocks, has to get ready for REDD+. We construct a historical reference level using available forest inventory data combined with updated 2008 and 2009 in situ carbon density data for Sri Lankan forests. Furthermore, we use a combination of qualitative and quantitative data to attribute the clearing of Sri Lankan forests in the latest years for which national forest inventory data are available, 1992-1996, to various proximate drivers and to estimate the opportunity cost of forest conservation. We estimate that baseline deforestation emissions in Sri Lanka amounted to 17MtCO(2)yr(-1) in the 1992-1996 period, but conclude that it is challenging for Sri Lanka to produce a robust and accurate reference level due to the lack of nationally based inventories. We find that the majority of forest clearing (87%) is due to small-scale, rainfed farming, with the two other major drivers being rice and tea cultivation. Further, Sri Lankan revenues from REDD+ participation could be substantial, but they are sensitive to REDD+ policy transaction cost, highly uncertain timber revenues, and particularly the carbon price paid for emission reductions. The latter needs to be higher than $5-10/tCO(2) if there are to be substantial incentives for Sri Lanka to participate in REDD+. There is, however, a large gap in the knowledge of deforestation drivers that needs to be filled if Sri Lanka is to formulate an effective policy response to forest degradation in REDD+. For successful REDD+ implementation in Sri Lanka to happen, technological assistance, readiness assistance, and continued political momentum are crucial.

GIS-based support tool system for decision-making regarding local forest protection: illustrations from Orissa, India.

A support tool system comprising risk and priority analyses was illustrated in a geographical information system environment and also tested with data from two forest protection areas for comparison of the system output. The system is recommended as a management monitoring tool for areas where village forest protection at a local level is taking place. The geographical area in the eastern part of India is subject to scarcity of forest resources and is representative in the context of widespread occurrence of local forest protection. Data used were topography, hectares protected, population census, distance to forest and other villages, degree of forest regeneration, presence of plantations, age of protection, surrounding forest resources, and population mix. Methods used were digitizing information for the systems' different layers, analyses of satellite information, field work, gathering of local information, and the application of five risk/priority analyses: erosion, ecological and institutional sustainability, conflict, and degree of dependency. Questions asked were how the different analyses should be interpreted and how the system could be kept updated. The results show that the system needs resource-demanding and field assistance to be kept dynamic. The system is also dependent on the interpretations of the analyses. The limits or levels of assistance for forest management depend on the resources available. The system illustrates how a tool can be utilized for decisions regarding input of resources. It can further be very useful in defining and comparing different areas in order to detect areas in need of assistance and the type of help needed.