• Energy Research

While the fuelwood crises predicted in the 1980s have not materialized, the potential for fuelwood demand to exceed supply remains for many rural areas, particularly in Africa where fuelwood is the primary source of domestic energy. The sustainability of fuelwood harvesting from a semi-arid savanna ecosystem was investigated at a rural village where shortages have been predicted. Repeated sampling over a period of 7 years revealed a stable supply of wood from harvesting areas. The number and thickness of stems harvested did not decline as expected, nor did the use of undesirable species. This is consistent with long-term changes in the structure of the woody layer of the harvesting area, where increases rather than decreases in plant density have occurred. The ability of local species to survive regular damage, coppice rapidly, and reproduce when still well below their adult sizes, together with social factors that limit the rate of harvesting, appears to have produced an ecologically sustainable harvesting system. However, the estimated biomass of fuelwood harvested was far below existing estimates of fuelwood consumption in the village, suggesting that fuelwood supply has not kept up with demand. Transformation of harvesting areas for housing and crop fields, rather than increasing demand, is the most likely cause of this.

While the fuelwood crises predicted in the 1980s have not materialized, the potential for fuelwood demand to exceed supply remains for many rural areas, particularly in Africa where fuelwood is the primary source of domestic energy. The sustainability of fuelwood harvesting from a semi-arid savanna ecosystem was investigated at a rural village where shortages have been predicted. Repeated sampling over a period of 7 years revealed a stable supply of wood from harvesting areas. The number and thickness of stems harvested did not decline as expected, nor did the use of undesirable species. This is consistent with long-term changes in the structure of the woody layer of the harvesting area, where increases rather than decreases in plant density have occurred. The ability of local species to survive regular damage, coppice rapidly, and reproduce when still well below their adult sizes, together with social factors that limit the rate of harvesting, appears to have produced an ecologically sustainable harvesting system. However, the estimated biomass of fuelwood harvested was far below existing estimates of fuelwood consumption in the village, suggesting that fuelwood supply has not kept up with demand. Transformation of harvesting areas for housing and crop fields, rather than increasing demand, is the most likely cause of this.

Employment is a sought-after conservation-based benefit. The national Environmental Monitor (EM) programme was established in 2013 to address challenges of unemployment and biodiversity conservation adjacent to and inside South African protected areas (PAs). We used qualitative and quantitative methods to interview 109 EMs working in the Kruger to Canyons Biosphere Region, an area encompassing 72 PAs including the Kruger National Park, to document the positive and negative, tangible and intangible impacts of their jobs at an individual, family and community level. We recorded an extensive list of material (e.g. monetary income, improved health and shelter) and psychological well-being impacts (improved self-esteem, empowerment and personal image). Our findings highlight the role of learning new things and having positive social connections in the workplace. We suggest that positive workplace well-being is important for organisational sustainability in the conservation sector and has a role to play in reducing wildlife crime. Conservation implications: Understanding workplace well-being in the conservation sector is important not only for ensuring benefit flow by facilitating personal, family and community well-being, but also for enhancing productivity through increased performance and organisational citizenship behaviour. These findings have direct implications for people and wildlife globally in the context of increasing pressure for PAs to demonstrate their societal contributions, while financial resources for PA management decrease and the illegal use of wildlife inside parks is increasingly becoming a threat to both biodiversity and people.

Employment is a sought-after conservation-based benefit. The national Environmental Monitor (EM) programme was established in 2013 to address challenges of unemployment and biodiversity conservation adjacent to and inside South African protected areas (PAs). We used qualitative and quantitative methods to interview 109 EMs working in the Kruger to Canyons Biosphere Region, an area encompassing 72 PAs including the Kruger National Park, to document the positive and negative, tangible and intangible impacts of their jobs at an individual, family and community level. We recorded an extensive list of material (e.g. monetary income, improved health and shelter) and psychological well-being impacts (improved self-esteem, empowerment and personal image). Our findings highlight the role of learning new things and having positive social connections in the workplace. We suggest that positive workplace well-being is important for organisational sustainability in the conservation sector and has a role to play in reducing wildlife crime. Conservation implications: Understanding workplace well-being in the conservation sector is important not only for ensuring benefit flow by facilitating personal, family and community well-being, but also for enhancing productivity through increased performance and organisational citizenship behaviour. These findings have direct implications for people and wildlife globally in the context of increasing pressure for PAs to demonstrate their societal contributions, while financial resources for PA management decrease and the illegal use of wildlife inside parks is increasingly becoming a threat to both biodiversity and people.

Daily minimum and maximum air temperature (degrees Celsius), total precipitation (Millimeter) and average incoming solar radiation (Watts per square meter) were computed from 288 five-minute samples for each day from 2021-10-08 to 2024-09-30, from an automatic weather station based at the South African Wildlife College. Sensor specifications and calibration data can be obtained from here: https://doi.org/10.15493/OBSDB.DOCS.31032022

Daily minimum and maximum air temperature (degrees Celsius), total precipitation (Millimeter) and average incoming solar radiation (Watts per square meter) were computed from 288 five-minute samples for each day from 2021-10-08 to 2024-09-30, from an automatic weather station based at the South African Wildlife College. Sensor specifications and calibration data can be obtained from here: https://doi.org/10.15493/OBSDB.DOCS.31032022

Tree biomass is an integrated measure of net growth and is critical for understanding, monitoring, and modeling ecosystem functions. Despite the importance of accurately measuring tree biomass, several fundamental barriers preclude direct measurement at large spatial scales, including the facts that trees must be felled to be weighed and that even modestly sized trees are challenging to maneuver once felled. Allometric methods allow for estimation of tree mass using structural characteristics, such as trunk diameter. Savanna trees present additional challenges, including limited available allometry and a prevalence of multiple stems per individual. Here we collected airborne lidar data over a semiarid savanna adjacent to the Kruger National Park, South Africa, and then harvested and weighed woody plant biomass at the plot scale to provide a standard against which field and airborne estimation methods could be compared. For an existing airborne lidar method, we found that half of the total error was due to averaging canopy height at the plot scale. This error was eliminated by instead measuring maximum height and crown area of individual trees from lidar data using an object‐based method to identify individual tree crowns and estimate their biomass. The best object‐based model approached the accuracy of field allometry at both the tree and plot levels, and it more than doubled the accuracy compared to existing airborne methods (17% vs. 44% deviation from harvested biomass). Allometric error accounted for less than one‐third of the total residual error in airborne biomass estimates at the plot scale when using allometry with low bias. Airborne methods also gave more accurate predictions at the plot level than did field methods based on diameter‐only allometry. These results provide a novel comparison of field and airborne biomass estimates using harvested plots and advance the role of lidar remote sensing in savanna ecosystems.

Tree biomass is an integrated measure of net growth and is critical for understanding, monitoring, and modeling ecosystem functions. Despite the importance of accurately measuring tree biomass, several fundamental barriers preclude direct measurement at large spatial scales, including the facts that trees must be felled to be weighed and that even modestly sized trees are challenging to maneuver once felled. Allometric methods allow for estimation of tree mass using structural characteristics, such as trunk diameter. Savanna trees present additional challenges, including limited available allometry and a prevalence of multiple stems per individual. Here we collected airborne lidar data over a semiarid savanna adjacent to the Kruger National Park, South Africa, and then harvested and weighed woody plant biomass at the plot scale to provide a standard against which field and airborne estimation methods could be compared. For an existing airborne lidar method, we found that half of the total error was due to averaging canopy height at the plot scale. This error was eliminated by instead measuring maximum height and crown area of individual trees from lidar data using an object‐based method to identify individual tree crowns and estimate their biomass. The best object‐based model approached the accuracy of field allometry at both the tree and plot levels, and it more than doubled the accuracy compared to existing airborne methods (17% vs. 44% deviation from harvested biomass). Allometric error accounted for less than one‐third of the total residual error in airborne biomass estimates at the plot scale when using allometry with low bias. Airborne methods also gave more accurate predictions at the plot level than did field methods based on diameter‐only allometry. These results provide a novel comparison of field and airborne biomass estimates using harvested plots and advance the role of lidar remote sensing in savanna ecosystems.

Increases in the abundance of woody species have been reported to affect the provisioning of ecosystem services in drylands worldwide. However, it is virtually unknown how multiple biotic and abiotic drivers, such as climate, grazing, and fire, interact to determine woody dominance across global drylands. We conducted a standardized field survey in 304 plots across 25 countries to assess how climatic features, soil properties, grazing, and fire affect woody dominance in dryland rangelands. Precipitation, temperature, and grazing were key determinants of tree and shrub dominance. The effects of grazing were determined not solely by grazing pressure but also by the dominant livestock species. Interactions between soil, climate, and grazing and differences in responses to these factors between trees and shrubs were key to understanding changes in woody dominance. Our findings suggest that projected changes in climate and grazing pressure may increase woody dominance in drylands, altering their structure and functioning.