Savanna Land Research Articles

Identification of Forest Fire Vulnerable Forest Types and Suitable Areas for Forest Restoration in Sri Lanka

Forest fire is the main driver on deforestation that severely impact for the forest resources annually. As per the past records of forest fires and according to the Forest Department data, annually about 100 ha to 1,000 ha of forest and forest plantation were destroyed due to forest fire in Sri Lanka. According to the current government mandate called “Vistas of Prosperity of Splendors”, percentage of forest cover of Sri Lanka will be increased from 29.7% to 30% at the end of 2025. In order to achieve this target, forest degradation and deforestation need to reduce while improving the forest restoration activities. On the other hand, still, the Forest Department does not have proper forest fire vulnerable area maps to identify the threaten forest resources for forest fires. In order to achieve the forest cover enhancement target in Sri Lanka the Forest Department need to be identify the forest fire impacted forest types and proper land areas for forest restoration activities. In this study shape file like forest cover, population density, forest fire ignition points, temperature and rainfall data from 2000 to 2020, slope and elevation data were used to analysis. Using several GIS tools such as special joints, intersect tools forest fire vulnerable forest type maps was created by using ArcGIS Pro software. Multi-criterial analysis technique was used to perform to identification of site suitability for replanting activities. Findings clearly indicated that dry monsoon forests are having high vulnerability for the forest fires followed by the forest plantation. The forested areas that are having canopy cover equal of less than 15% are the area which are more suitable for forest cover enhancement programs. These forest types are open and sparse forest lands, scrublands, and savanna lands. On the other hand, dry monsoon forested areas are also having some potential for replanting activities that cover 2/3 of the total forest lands. High elevation forested lands are normally not suitable for forest restoration being having high operation and maintenance costs as well as high canopy cover. Scrubland, open and sparse forested areas that are located in Rathnapura and Kaluthara districts are the best forested areas that can be highly recommended for forest restoration activities. On the other hand, open and sparse forest, savanah, and scrubland forested land areas in Monagarala, Hambanthota, Ampara, and Batticaloa districts can be used for the forest restoration activities.
 Keywords: Forest fire, Multi-criterial factors, Weighted overlay, Forest restoration, Dry monsoon forest

Using Very-High-Resolution Multispectral Classification to Estimate Savanna Fractional Vegetation Components

Characterizing compositional and structural aspects of vegetation is critical to effectively assessing land function. When priorities are placed on ecological integrity, remotely sensed estimates of fractional vegetation components (FVCs) are useful for measuring landscape-level habitat structure and function. In this study, we address whether FVC estimates, stratified by dominant vegetation type, vary with different classification approaches applied to very-high-resolution small unoccupied aerial system (UAS)-derived imagery. Using Parrot Sequoia imagery, flown on a DJI Mavic Pro micro-quadcopter, we compare pixel- and segment-based random forest classifiers alongside a vegetation height-threshold model for characterizing the FVC in a southern African dryland savanna. Results show differences in agreement between each classification method, with the most disagreement in shrub-dominated sites. When compared to vegetation classes chosen by visual identification, the pixel-based random forest classifier had the highest overall agreement and was the only classifier not to differ significantly from the hand-delineated FVC estimation. However, when separating out woody biomass components of tree and shrub, the vegetation height-threshold performed better than both random-forest approaches. These findings underscore the utility and challenges represented by very-high-resolution multispectral UAS-derived data (~10 cm ground resolution) and their uses to estimate FVC. Semi-automated approaches statistically differ from by-hand estimation in most cases; however, we present insights for approaches that are applicable across varying vegetation types and structural conditions. Importantly, characterization of savanna land function cannot rely only on a “greenness” measure but also requires a structural vegetation component. Underscoring these insights is that the spatial heterogeneity of vegetation structure on the landscape broadly informs land management, from land allocation, wildlife habitat use, natural resource collection, and as an indicator of overall ecosystem function.

Limitations of WRF land surface models for simulating land use and land cover change in Sub-Saharan Africa and development of an improved model (CLM-AF v. 1.0)

Abstract. Land use and land cover change (LULCC) impacts local and regional climates through various biogeophysical processes. Accurate representation of land surface parameters in land surface models (LSMs) is essential to accurately predict these LULCC-induced climate signals. In this work, we test the applicability of the default Noah, Noah-MP, and Community Land Model (CLM) LSMs in the Weather Research and Forecasting (WRF) model over Sub-Saharan Africa. We find that the default WRF LSMs do not accurately represent surface albedo, leaf area index, and surface roughness in this region due to various flawed assumptions, including the treatment of the MODIS woody savanna land use and land cover (LULC) category as closed shrubland. Consequently, we developed a WRF CLM version with more accurate African land surface parameters (CLM-AF), designed such that it can be used to evaluate the influence of LULCC. We evaluate meteorological performance for the default LSMs and CLM-AF against observational datasets, gridded products, and satellite estimates. Further, we conduct LULCC experiments with each LSM to determine if differences in land surface parameters impact the LULCC-induced climate responses. Despite clear deficiencies in surface parameters, all LSMs reasonably capture the spatial pattern and magnitude of near-surface temperature and precipitation. However, in the LULCC experiments, inaccuracies in the default LSMs result in illogical localized temperature and precipitation changes. Differences in thermal changes between Noah-MP and CLM-AF indicate that the temperature impacts from LULCC are dependent on the sensitivity of evapotranspiration to LULCC in Sub-Saharan Africa. Errors in land surface parameters indicate that the default WRF LSMs considered are not suitable for LULCC experiments in tropical or Southern Hemisphere regions and that proficient meteorological model performance can mask these issues. We find CLM-AF to be suitable for use in Sub-Saharan Africa LULCC studies, but more work is needed by the WRF community to improve its applicability to other tropical and Southern Hemisphere climates.

Impact of land use changes on soil quality and species diversity in the Vindhyan dry tropical region of India

AbstractConversion of forest land into different land use types is the primary cause of degradation of land resources, which in turn alters nutrient and carbon cycles, land productivity and diversity of species. There is scarcity of information about land-use changes (LUC) and their effect on relationship of soil quality and species diversity at landscape level in the Vindhyan dry tropical region. We evaluated the impact of land-use changes on soil physicochemical quality and the influence of these qualities on species diversity and organic matter accumulation. We also established the relationship between soil quality indicators and species diversity parameters. To examine impact of LUC, we did a detailed field survey and analysed selected soil quality indicators by standard methods. We examined species diversity parameters and established the relationship between soil quality and species diversity. We found that there is a marked decline in soil porosity, water-holding capacity and soil moisture due to LUC. Conversion from forest land (FL) to savanna land (SL) resulted in soil organic carbon decreasing by ∼40–50%. The decrease was more pronounced in cultivated land (CL) and degraded land (DL) (65–70% and 83–85%, respectively). In the case of total N, maximum decrease in total N of 83–87% was noted in DL as compared with FL. The poor soil quality indicators in degraded and agricultural land can be explained by the interaction between the soil organic carbon and nitrogen loss with diversity loss. This study recommends that for management/restoration of land resources, planning strategies should consider the current landscape structure, with land-use planning.

Characterization and Trends of Fine Particulate Matter (PM2.5) Fire Emissions in the Brazilian Cerrado during 2002–2017

Fire occurrence is a major disturbance in the Brazilian Cerrado, which is driven by both natural and anthropogenic activities. Despite increasing efforts for monitoring the Cerrado, a biome-scale study for quantifying and understanding the variability of fire emissions is still needed. We aimed at characterizing and finding trends in Particulate Matter with diameter less than 2.5 µm (PM2.5) fire emissions in the Brazilian Cerrado using the PREP-CHEM-SRC emissions preprocessing tool and Moderate Resolution Imaging Spectroradiometer (MODIS) active fires datasets for the 2002–2017 period. Our results showed that, on average, the Cerrado emitted 1.08 Tg year−1 of PM2.5 associated with fires, accounting for 25% and 15% of the PM2.5 fire emissions in Brazil and South America, respectively. Most of the PM2.5 fire emissions were concentrated in the end of the dry season (August, 0.224 Tg month−1 and September, 0.386 Tg month−1) and in the transitional month (October, 0.210 Tg month−1). Annually, 66% of the total emissions occurred over the savanna land cover; however, active fires that were detected in the evergreen broadleaf land cover tended to emit more than active fires occurring in the savanna land cover. Spatially, each 0.1° grid cell emitted, on average, 0.5 Mg km−2 year−1 of PM2.5 associated with fires, but the values can reach to 16.6 Mg km−2 year−1 in a single cell. Higher estimates of PM2.5 emissions associated with fires were mostly concentrated in the northern region, which is the current agricultural expansion frontier in this biome. When considering the entire Cerrado, we found an annual decreasing trend representing -1.78% of the annual average PM2.5 emitted from fires during the period analyzed, however, the grid cell analysis found annual trends representing ± 35% of the annual average PM2.5 fire emissions.

The nature and spatial variability of lowland savanna soils: Improving the resolution of soil properties to support land management policy

AbstractA fresh approach is presented to address the increasingly urgent need for alternative land management strategies in savannas. We illustrate how fine‐scale information of soil characteristics can be used to enable a more precise delimitation of sites suitable for different forms of land stewardship, including agro‐pastoral activities, forestry, biodiversity and tourism. By collating data from previous soil surveys, and augmenting this with targeted new surveys, we produce the first national data set of soil properties for the lowland savannas of Belize. Most of these soils are typical of savanna soils worldwide, that is acidic (mean surface pH = 5.7), nutrient‐poor (mean surface total exchangeable bases [TEB] = 3.4 cmol kg−1) and coarse‐textured (mean surface clay = 13.0%). Nevertheless, there is a marked spatial variability across the country in these soil properties. Some soils exhibit unusually high subsurface clay fractions (max = 73%), whilst other sites have exceptionally high pH in lower horizons (max = 8.4). Cluster analysis is used to group sites with similar soil properties. Across 79 sites, there is a clear division between soils with high clay percentages and those with coarser textures. These are sub‐divided into five groups based on further differences in parent material, chemical properties and site characteristics. Mapping the locations of these groups enables more specific land use recommendations to be made. This ability to make targeted land use recommendations from fine‐scale soil information represents an advance over the previous national land use policy, where all savanna lands were considered unsuitable for any form of agriculture. This approach could be applied to marginal savannas worldwide.

Large scale operational soil moisture mapping from passive MW radiometry: SMOS product evaluation in Europe & USA

Earth Observation (EO) allows deriving from a range of sensors, often globally, operational estimates of surface soil moisture (SSM) at range of spatiotemporal resolutions. Yet, an evaluation of the accuracy of those products in a variety of environmental conditions has been often limited. In this study, the accuracy of the SMOS SSM global operational product across 2 continents (USA, and Europe) and a range of land use/cover types is investigated. SMOS predictions were compared against near concurrent in-situ SSM measurements from the FLUXNET observational network. In total, 7 experimental sites were used to assess the accuracy of SMOS derived soil moisture for 2 complete years of observations (2010–2011). The accuracy of the SMOS SSM product is investigated in different seasons for the seasonal cycle as well as different continents and land use/cover types. Results showed a generally reasonable agreement between the SMOS product and the in-situ soil moisture measurements in the 0–5 cm soil moisture layer. Root Mean Square Error (RMSE) in most cases was close to 0.1 m3 m−3 (minimum 0.067 m3 m−3). With a few exceptions, Pearson’s correlation coefficient was found up to approx. 55%. Grassland, shrublands and woody savanna land cover types attained a satisfactory agreement between satellite derived and in-situ measurements but needleleaf forests had lower correlation. Better agreement was found for the grassland sites in both continents. Seasonally, summer and autumn underperformed spring and winter. Our study results provide supportive evidence of the potential value of this operational product for meso-scale studies in a range of practical applications, helping to address key challenges present nowadays linked to food and water security.

Operational Soil Moisture from ASCAT in Support of Water Resources Management

This study provides the results of an extensive investigation of the Advanced Scaterometter (ASCAT) surface soil moisture global operational product accuracy across three continents (United States of America (USA), Europe, and Australia). ASCAT predictions of surface soil moisture were compared against near concurrent in situ measurements from the FLUXNET observational network. A total of nine experimental sites were used to assess the accuracy of ASCAT Surface Soil Moisture (ASCAT SSM) predictions for two complete years of observations (2010, 2011). Results showed a generally reasonable agreement between the ASCAT product and the in situ soil moisture measurements in the 0–5 cm soil moisture layer. The Root Mean Square Error (RMSE) was below 0.135 m3 m−3 at all of the sites. With a few exceptions, Pearson’s correlation coefficient was above 45%. Grassland, shrublands, and woody savanna land cover types exhibited satisfactory agreement in all the sites analyzed (RMSE ranging from 0.05 to 0.13 m3 m−3). Seasonal performance was tested, but no definite conclusion can be made with statistical significance at this time, as the seasonal results varied from continent to continent and from year to year. However, the satellite and in situ measurements for Needleleaf forests were practically uncorrelated (R = −0.11 and −0.04). ASCAT predictions overestimated the observed values at all of the sites in Australia. A positive bias of approximately 0.05 m3 m−3 was found with respect to the observed values that were in the range 0–0.3 m3 m−3. Better agreement was observed for the grassland sites in most cases (RMSE ranging from 0.09 to 0.10 m3 m−3 and R from 0.46 to 0.90). Our results provide supportive evidence regarding the potential value of the ASCAT global operational product for meso-scale studies and the relevant practical applications. A key contribution of this study is a comprehensive evaluation of ASCAT product soil moisture estimates at different sites around the globe. These sites represent a variety of climatic, environmental, biome, and topographical conditions.

Densities and population sizes of raptors in Uganda’s conservation areas

Projected increases in Africa's human population over the next 40 years point to further, large-scale conversion of natural habitats into farmland, with far-reaching consequences for raptor species, some of which are now largely restricted to protected areas (PAs). To assess the importance of PAs for raptors in Uganda, we conducted an annual road survey through savanna, pastoral and agricultural land during 2008–2015. Here, we present density estimates for 34 diurnal raptor species, 17 of which were encountered largely or entirely within PAs. These included seven out of eight globally threatened or near-threatened species surveyed. Based mainly on published demographic values, we converted density estimates (birds 100 km−2) to numbers of adult pairs, for 10 resident, savanna-dependent species. We then estimated adult population sizes within conservation areas (individual PAs and clusters of contiguous PAs), based on the area of savanna in each site. This suggested that two threatened residents, Martial Eagle Polemaetus bellicosus and Lappet-faced Vulture Torgos tracheliotos, have national breeding populations of just 53–75 and 74–105 pairs, respectively. A third species, White-headed Vulture Trigonoceps occipitalis, may have a breeding population of just 22–32 pairs. In each case, at least 90% of pairs are thought to reside within Uganda's five largest conservation areas. In three cases our estimates of pair density were markedly lower than in other studies, while in six cases they were broadly consistent with published findings, often derived using more intensive survey methods. Further work is required to determine the accuracy of our estimates for individual conservation areas, and to assess the long-term viability of Uganda's threatened raptor populations.

MODIS detection of vegetation changes and investigation of causal factors in Poyang Lake basin, China for 2001–2015

In recent decades, vegetation has shown an overall greening trend in response to rising global temperatures. At the same time, vegetation browning is still worthy of attention, particularly in humid regions with dense vegetation coverage. This study used 15 years (2001–2015) of Terra Moderate-resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) data in an effort to detect the overall trends and abrupt changes in vegetation activity over the Poyang Lake basin, which is a typical humid region that contains the largest freshwater lake in China. MODIS NDVI data showed a vegetation greening trend over 94.9% of the basin land. Although the basin has been extensively afforested since the 1980s, there was still a vegetation browning trend over 5.1% of the basin land area, primarily as a result of urbanization. Abrupt vegetation decreases were observed over 7.9% of the basin land area from 2004 to 2012. Most of the decreases were likely caused by the nationwide snow storms in early 2008 and the widespread insect outbreaks as a result of abnormal hydrometeorological conditions. Abrupt vegetation increases were observed over 1.6% of the basin land area in the same period. Most of the increases were likely attributed to the continued efforts of afforestation that transformed large woody savanna lands to mixed forests. The results provided spatial details, time nodes and causal factors of vegetation changes, particularly vegetation decreases, which will benefit government organizations when taking remedial measures.

THE SACRED SITE: THE CONSERVATION BASED ON THE LOCAL PEOPLE IN TENGGER COMMUNITY AND ITS POTENTIAL AS ECOTOURISM ACTIVITIES

Tengger is one of the Java sub-tribes that has a belief system in the form of a life view calledKejawen. Kejawen's life is a view that is considered holistic in looking at the environment. The traditionalwisdom of the Tengger community in the management of natural resources is one of the living andsustainable local wisdom in Indonesia. One of the local wisdom associated with environmental managementis the existence of sacred areas as a part of environmental conservation. This research was conducted inNgadas Village, Poncokusumo District, Malang Regency. The purpose of this study is to study the types ofareas that are sacred by the Tengger community and the factors behind the existence of the area as a partof the conservation-based ecotourism. This research was conducted by interviewing the key person of thetraditional leader. The interview materials in questions include the types of sacred places and the reasonbehind the area is sacred. The research results showed that the form of preservation of certain sacredareas has a unique ecosystem and shows the historical ties. The areas considered by the Ngadascommunity as sacred sites have indigenous values such as Pedanyangan, Sanggar Agung, Mbah Sedektombs, Punden Kutungan, the mount of Bromo, the mount of Semeru, Savanna land and Bromo caldera andother sacred sites. The sacred place is highly respected by the Tengger people. Norms and values inTengger culture incorporate with the respect for the sacred places. The existence of these sacred areas canbe used as a part of environmental conservation-based ecotourism.

Satellite observations for describing fire patterns and climate-related fire drivers in the Brazilian savannas

Abstract. In the Brazilian savannas (Cerrado biome) fires are natural and a tool for shifting land use; therefore, temporal and spatial patterns result from the interaction of climate, vegetation condition and human activities. Moreover, orbital sensors are the most effective approach to establish patterns in the biome. We aimed to characterize fire, precipitation and vegetation condition regimes and to establish spatial patterns of fire occurrence and their correlation with precipitation and vegetation condition in the Cerrado. The Cerrado was first and second biome for the occurrence of burned areas (BA) and hotspots, respectively. Occurrences are higher during the dry season and in the savanna land use. Hotspots and BA tend to decrease, and concentrate in the north, but more intense hotspots are not necessarily located where concentration is higher. Spatial analysis showed that averaged and summed values can hide patterns, such as for precipitation, which has the lowest average in August, but minimum precipitation in August was found in 7 % of the Cerrado. Usually, there is a 2–3-month lag between minimum precipitation and maximum hotspots and BA, while minimum VCI and maximum hotspots and BA occur in the same month. Hotspots and BA are better correlated with VCI than precipitation, qualifying VCI as an indicator of the susceptibility of vegetation to ignition.

Greenhouse gas and energy balance of Jatropha biofuel production systems of Burkina Faso

Jatropha curcas has been introduced as a low-cost energy crop in Burkina Faso for the production of straight vegetable oil (SVO) and biodiesel. It is cultivated in different plantation systems including smallholder inter-plantings with annual crops, large-scale monoculture, afforestation on marginal land, in traditional hedge systems along contour stone walls, and in living fences. We performed Life Cycle Assessment of these Jatropha systems using empirical data on yields and carbon stocks, and accounting for changes in agro-ecosystem provisioning and regulating services that occurred after the land conversion to Jatropha. The study found that all J. curcas production pathways substantially reduced greenhouse gas emission (68–89%) and saved energy (65–90%) compared to diesel fuel. Highest values are achievable under the assumption that by-products (husks, seed cake, glycerin) are used for energy generation. The decentralized production of SVO supplied by feedstocks from intercropping and hedgerow systems seems to be most promising option. However, very low land-use efficiency (6.5–9.5 GJ ha−1 production) characterized Jatropha intercropping and monoculture plantations, rendering the plant a competitor to food crops and increasing the risk of conversion of savanna land to Jatropha cultivation. Jatropha plantings on marginal lands largely failed. High labor requirements constrain integration of Jatropha plantation systems within small farmholdings. Currently, the traditional hedge systems show the lowest land-use replacement potential and labor needs while providing multiple ecosystem services, but alone cannot satisfy rural energy needs. In order to reach energy supply targets without claiming more land and compromising other ecosystem services, the J. curcas plantation systems in Burkina Faso need to be made more efficient through plant breeding and improved agronomic management.

Limited long-term effects of moderate livestock grazing and prescribed early fire on soil and root processes in Sudanian savanna-woodlands, West Africa

Savanna ecosystems are mainly shaped by climate, soil properties and ecological disturbances such as fire and grazing. The biophysical effects of fire and grazing depend both on their intensities and season of occurrence. The long-term effects of fire and grazing on key soil parameters are still largely unknown in West African savanna ecosystems; yet the knowledge of these effects is crucial to our understanding and sustainable management of savanna ecosystems. This study provides scientific evidence of soil responses to both fire and grazing management, and their interactions, based on field-data from two case-studies. The data are drawn from a long-term factorial experiment that has been established since 1992 in two State Forest reserves in Burkina Faso that mainly differ in their soil attributes (i.e. shallow or deep soil). Root biomass, soil CO2 efflux, organic matter content and C/N ratio, and soil water properties were assessed on plots subjected to two different treatments (i.e. moderate grazing and prescribed burning) over a 20year period. The results indicated that at the site with shallow soil, for both root density and organic matter content there was no significant difference between the studied soil depths (i.e. 0–5cm and 5–10cm) nor a significant effect of treatment (both p>0.05). In contrast, at the site with deep soil, root density increases with soil depth (p=0.011); it is 5 times higher at depths of between 5 and 10cm (3.26±1.24g/dm3) compared to the top 5cm (0.67±0.20g/dm3). The organic matter content marginally decreases (p=0.048) with soil depth. The C/N ratio is higher (p<0.05) under an annual early fire treatment compared to the grazing treatments and control, particularly at the deep soil site. In addition, the CO2 efflux varies significantly with the treatment at the two sites (p<0.004); grazed plots have higher respiration rates than control and burnt plots. Finally, water infiltration rates do not vary significantly with fire and grazing after 20-years of treatment. Our results provide an insight into the long-term effects of fire and grazing on soil water infiltration and soil CO2 fluxes in savanna ecosystems. We conclude that effects of fire and grazing on savanna soil processes are limited. We also highlight our contrasting results between the studied soil attributes across the two sites, providing evidence that depending on site differences, the effects of fire and grazing on soil chemical and water properties might change, suggesting caution when making extrapolation in the context of savanna land use planning and management.

Quantifying the relative importance of greenhouse gas emissions from current and future savanna land use change across northern Australia

Abstract. The clearing and burning of tropical savanna leads to globally significant emissions of greenhouse gases (GHGs); however there is large uncertainty relating to the magnitude of this flux. Australia's tropical savannas occupy the northern quarter of the continent, a region of increasing interest for further exploitation of land and water resources. Land use decisions across this vast biome have the potential to influence the national greenhouse gas budget. To better quantify emissions from savanna deforestation and investigate the impact of deforestation on national GHG emissions, we undertook a paired site measurement campaign where emissions were quantified from two tropical savanna woodland sites; one that was deforested and prepared for agricultural land use and a second analogue site that remained uncleared for the duration of a 22-month campaign. At both sites, net ecosystem exchange of CO2 was measured using the eddy covariance method. Observations at the deforested site were continuous before, during and after the clearing event, providing high-resolution data that tracked CO2 emissions through nine phases of land use change. At the deforested site, post-clearing debris was allowed to cure for 6 months and was subsequently burnt, followed by extensive soil preparation for cropping. During the debris burning, fluxes of CO2 as measured by the eddy covariance tower were excluded. For this phase, emissions were estimated by quantifying on-site biomass prior to deforestation and applying savanna-specific emission factors to estimate a fire-derived GHG emission that included both CO2 and non-CO2 gases. The total fuel mass that was consumed during the debris burning was 40.9 Mg C ha−1 and included above- and below-ground woody biomass, course woody debris, twigs, leaf litter and C4 grass fuels. Emissions from the burning were added to the net CO2 fluxes as measured by the eddy covariance tower for other post-deforestation phases to provide a total GHG emission from this land use change. The total emission from this savanna woodland was 148.3 Mg CO2-e ha−1 with the debris burning responsible for 121.9 Mg CO2-e ha−1 or 82 % of the total emission. The remaining emission was attributed to CO2 efflux from soil disturbance during site preparation for agriculture (10 % of the total emission) and decay of debris during the curing period prior to burning (8 %). Over the same period, fluxes at the uncleared savanna woodland site were measured using a second flux tower and over the 22-month observation period, cumulative net ecosystem exchange (NEE) was a net carbon sink of −2.1 Mg C ha−1, or −7.7 Mg CO2-e ha−1. Estimated emissions for this savanna type were then extrapolated to a regional-scale to (1) provide estimates of the magnitude of GHG emissions from any future deforestation and (2) compare them with GHG emissions from prescribed savanna burning that occurs across the northern Australian savanna every year. Emissions from current rate of annual savanna deforestation across northern Australia was double that of reported (non-CO2 only) savanna burning. However, if the total GHG emission, CO2 plus non-CO2 emissions, is accounted for, burning emissions are an order of magnitude larger than that arising from savanna deforestation. We examined a scenario of expanded land use that required additional deforestation of savanna woodlands over and above current rates. This analysis suggested that significant expansion of deforestation area across the northern savanna woodlands could add an additional 3 % to Australia's national GHG account for the duration of the land use change. This bottom-up study provides data that can reduce uncertainty associated with land use change for this extensive tropical ecosystem and provide an assessment of the relative magnitude of GHG emissions from savanna burning and deforestation. Such knowledge can contribute to informing land use decision making processes associated with land and water resource development.

Seasonal Separation of African Savanna Components Using Worldview-2 Imagery: A Comparison of Pixel- and Object-Based Approaches and Selected Classification Algorithms

Separation of savanna land cover components is challenging due to the high heterogeneity of this landscape and spectral similarity of compositionally different vegetation types. In this study, we tested the usability of very high spatial and spectral resolution WorldView-2 (WV-2) imagery to classify land cover components of African savanna in wet and dry season. We compared the performance of Object-Based Image Analysis (OBIA) and pixel-based approach with several algorithms: k-nearest neighbor (k-NN), maximum likelihood (ML), random forests (RF), classification and regression trees (CART) and support vector machines (SVM). Results showed that classifications of WV-2 imagery produce high accuracy results (&gt;77%) regardless of the applied classification approach. However, OBIA had a significantly higher accuracy for almost every classifier with the highest overall accuracy score of 93%. Amongst tested classifiers, SVM and RF provided highest accuracies. Overall classifications of the wet season image provided better results with 93% for RF. However, considering woody leaf-off conditions, the dry season classification also performed well with overall accuracy of 83% (SVM) and high producer accuracy for the tree cover (91%). Our findings demonstrate the potential of imagery like WorldView-2 with OBIA and advanced supervised machine-learning algorithms in seasonal fine-scale land cover classification of African savanna.

Savanna Land Use and its Effect on Woody Plant Species Diversity in Borana, Southern Ethiopia

A study on the diversity of woody plant species of Boke salt valley landscape in a semi-arid ecosystem of Borana was conducted. The area is a volcanic crater lake with the lake at the bottom base. Vegetation of such volcanic areas is expected to develop through the process of succession over years. Line transects were laid along four geographical directions (aspects). A total of 22 quadrats (20 m x 20 m) were used for woody vegetation sampling and the height and diameter at breast height (DBH) data were collected for each species. Vegetation data were analyzed using PC-ORD, CANOCO and SPSS software. A total of 24 woody plant species representing 18 genera in 14 families were recorded. The density of woody plants recorded in the present study was 2622 individuals ha-1. The results showed that the woody plant species diversity and evenness indices were 2.1 and 0.661, respectively. Moreover, three plant community types were identified namely: Suaeda monoica, Maerua triphylla-Acalypha fruticosa and Hibiscus aponeurus-Solanum somalensis. However, Boke salt valley landscape is under intensive human exploitation. Hence, participatory natural resource management for the sustainable use of such scarce resources is very crucial.

Impacts of an extreme cyclone event on landscape-scale savanna fire, productivity and greenhouse gas emissions

North Australian tropical savanna accounts for 12% of the world’s total savanna land cover. Accordingly, understanding processes that govern carbon, water and energy exchange within this biome is critical to global carbon and water budgeting. Climate and disturbances drive ecosystem carbon dynamics. Savanna ecosystems of the coastal and sub-coastal of north Australia experience a unique combination of climatic extremes and are in a state of near constant disturbance from fire events (1 in 3 years), storms resulting in windthrow (1 in 5–10 years) and mega-cyclones (1 in 500–1000 years). Critically, these disturbances occur over large areas creating a spatial and temporal mosaic of carbon sources and sinks. We quantify the impact on gross primary productivity (GPP) and fire occurrence from a tropical mega-cyclone, tropical Cyclone Monica (TC Monica), which affected 10 400 km2 of savanna across north Australia, resulting in the mortality and severe structural damage to ∼140 million trees. We estimate a net carbon equivalent emission of 43 Tg of CO2-e using the moderate resolution imaging spectroradiometer (MODIS) GPP (MOD17A2) to quantify spatial and temporal patterns pre- and post-TC Monica. GPP was suppressed for four years after the event, equivalent to a loss of GPP of 0.5 Tg C over this period. On-ground fuel loads were estimated to potentially release 51.2 Mt CO2-e, equivalent to ∼10% of Australia’s accountable greenhouse gas emissions. We present a simple carbon balance to examine the relative importance of frequency versus impact for a number of key disturbance processes such as fire, termite consumption and intense but infrequent mega-cyclones. Our estimates suggested that fire and termite consumption had a larger impact on Net Biome Productivity than infrequent mega-cyclones. We demonstrate the importance of understanding how climate variability and disturbance impacts savanna dynamics in the context of the increasing interest in using savanna landscapes for enhanced carbon sinks in emission offset schemes.

Amazon Forest &amp; Savanna Lands: A guide to the climates, vegetation, landscapes, and soils of central tropical South America

Soil Science Society of America JournalVolume 76, Issue 5 p. 1928-1928 Book Review Amazon Forest & Savanna Lands: A guide to the climates, vegetation, landscapes, and soils of central tropical South America Charles Allan Jones, Corresponding Author Charles Allan Jones cajones@tamu.edu 2225 Irwin Street, Fort Worth, TX, 76110 USACorresponding author (cajones@tamu.edu)Search for more papers by this author Charles Allan Jones, Corresponding Author Charles Allan Jones cajones@tamu.edu 2225 Irwin Street, Fort Worth, TX, 76110 USACorresponding author (cajones@tamu.edu)Search for more papers by this author First published: 12 September 2012 https://doi.org/10.2136/sssaj2012.0002br Thomas T. Cochrane and Thomas A. Cochrane (Ed.)., T.T. Cochrane (Agrotecnologica Amazonica S.A., Bolivia) and T.A. Cochrane (University of Canterbury, Christchurch, New Zealand); printed and distributed by Createspace (an Amazon publishing company), Scotts Valley, CA, U.S.A. 2010. Revised 2011. 190 p. $49.00. ISBN 9781452866376 All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume76, Issue5September 2012Pages 1928-1928 RelatedInformation

Estimation of effective fallow availability for the prediction of yam productivity at the regional scale using model-based multiple scenario analysis

Soil fertility restoration and crop performance in many developing countries with low input agriculture strongly relies on fallow duration and management. More precise information about the availability of fallow land may provide a way to improve the simulation of yam (Dioscorea spp.) yields at the regional scale which has hardly been considered in prevailing approaches to model regional crop production. The probable reason behind this is scarce availability of data on fallow duration and variation across the farms in a region. Therefore, this study attempts to estimate effective fallow availability for yam production at the regional scale and to simulate the effect of fallow on regional yam yield. Yam growth and yield were simulated with the EPIC model which was incorporated into a Spatial Decision Support System (SDSS) covering a typical catchment with variable land use intensity within the sub-humid savannah zone of West Africa. Yam-fallow rotations were simulated within 1120 quasi-homogenous spatial units (LUSAC=Land Use-Soil Association-Climate units) and aggregated to the 121 sub-basins and ten districts within the catchment under three different scenarios of fallow availability: (S1) Total savannah area was available as fallow land, (S2) 50% of the bush savannah was available as fallow land and (S3) 25% of the bush savannah was available as fallow land. The aggregation procedure adopted in this study was based on changes in the frequency of fallow-cropland classes within the sub-basins to render the SDSS sensitive to changes in fallow availability. Comparison of the average simulated tuber yield with the observed mean yield over the entire catchment showed that the simulations slightly overestimated the yields by 0.4% for scenario S1, whereas, underestimated by 14.2% and 36.8% in scenario S2 and S3 respectively. When compared with the effective fallow availability to maize, it was concluded that, (1) due to farmers preferences to plant yam mainly on virgin savanna land and as the first crop in the rotation after fallow, the effectively available fallow area for yam is higher than for maize and (2) the applied approach is suitable to derive effective fallow availability for yam production at the district scale.