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Influence of wildfires severity on tree composition and structure in Aberdare Afromontane Forest Ranges, Kenya
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Wildfires are uncontrolled fires fuelled by dry conditions, high winds, and flammable materials that profoundly impact vegetation, leading to significant consequences including noteworthy changes to ecosystems. In this study, we provide a novel methodology to understand and evaluate post-fire effects on vegetation. In regions affected by wildfires, earth-observation data from various satellite sources can be vital in monitoring vegetation and assessing its impact. These effects can be understood by detecting vegetation change over the years using a novel unsupervised method termed Deep Embedded Clustering (DEC), which enables us to classify regions based on whether there has been a change in vegetation after the fire. Our model achieves an impressive accuracy of 96.17%. Appropriate vegetation indices can be used to evaluate the evolution of vegetation patterns over the years; for this study, we utilized Enhanced Vegetation Index (EVI) based trend analysis showing the greening fraction, which ranges from 0.1 to 22.4 km² while the browning fraction ranges from 0.1 to 18.1 km² over the years. Vegetation recovery maps can be created to assess re-vegetation in regions affected by the fire, which is performed via a deep learning-based unsupervised method, Adaptive Generative Adversarial Neural Network Model (AdaptiGAN) on post-fire data collected from various regions affected by wildfire with a training error of 0.075 proving its capability. Based on the results obtained from the study, our approach tends to have notable merits when compared to pre-existing works.
Tropical forests provide habitats for diverse flora and fauna, in addition to playing a crucial role in climate regulation. They are being recognized for their roles as nature-based solutions to many sustainable development challenges, as shown by increased political commitment and global promises to reduce the rates of deforestation and boost the restoration of degraded forest ecosystems. Understanding tropical forest dynamics and their conservation status is therefore important. This study analysed the forest stand structure, the tree species composition and the regeneration status of Londiani Forest. In the three blocks of Londiani Forest, which are Kedowa, Chebewor and Londiani, belt transects that were 25 m wide and 1 km long were established. At every 200 m along the transects, 25 m × 25 m quadrats were set up in which an inventory of all the tree species was determined. Diameter tape was used to measure the diameter at breast height (DBH) 1.3 m above the ground. With the use of a Suunto angular clinometer, the tree height was measured. A nested 5 m × 5 m quadrat within the 25 m × 25 m quadrat was used to sample the saplings, while a 1m × 1 m quadrat was used to sample the seedlings. The quantities of seedlings and saplings were used to determine the state of regeneration. The data were entered into Microsoft Excel. The total stem density, species density, basal area, species basal area, relative density and species diversity were determined and extrapolated per hectare. A total of 1308 distinct trees from 34 different species and 24 families were counted. Kedowa recorded the highest (27) species richness, followed by Chebewor (19) and then Londiani (14). There was a statistically significant difference in the species richness among the three forest blocks (p < 0.05). Within the three forest blocks, there were no statistically significant variations in the basal area distribution (p > 0.005) or in the mean DBH (F = 0.560; p = 0.729) or height class distribution (F = 0.821; p = 0.558). There was a statistically significant difference in the stem density (F = 12.22; p = 0.005) and woody species diversity (F = 0.32; p = 0.001) within the three forests blocks. The similarity index ranged from 0.34–0.47. The presence of substantial numbers of seedlings and saplings in all forest blocks was an indication that there was regeneration.
This study presents a comprehensive analysis of historical fire and climatic data to estimate the monthly frequency of vegetation fires in Kenya. This work introduces a statistical model that captures the behavior of fire count data, incorporating temporal explanatory factors and emphasizing the predictive significance of maximum temperature and rainfall. By employing Bayesian approaches, the paper integrates literature information, simulation studies, and real-world data to enhance model performance and generate more precise prediction intervals that encompass actual fire counts. To forecast monthly fire occurrences aggregated from the Moderate Resolution Imaging Spectroradiometer (MODIS) data in Kenya (2000-2018), the study utilizes maximum temperature and rainfall values derived from global GeoTiff (.tif) files sourced from the WorldClim database. The evaluation of the widely used Negative Binomial (NB) model and the proposed Bayesian Negative Binomial (BNB) model reveals the superiority of the latter in accounting for seasonal patterns and long-term trends. The simulation results demonstrate that the BNB model outperforms the NB model in terms of Root Mean Square Error (RMSE), and Mean Absolute Scaled Error (MASE) on both training and testing datasets. Furthermore, when applied to real data, the Bayesian Negative Binomial model exhibits better performance on the test dataset, showcasing lower RMSE (163.22 vs. 166.67), lower MASE (1.12 vs. 1.15), and reduced bias (-2.52% vs. -2.62%) compared to the NB model. The Bayesian model also offers prediction intervals that closely align with actual predictions, indicating its flexibility in forecasting the frequency of monthly fires. These findings underscore the importance of leveraging past data to forecast the future behavior of the fire regime, thus providing valuable insights for fire control strategies in Kenya. By integrating climatic factors and employing Bayesian modeling techniques, the study contributes to the understanding and prediction of vegetation fires, ultimately supporting proactive measures in mitigating their impact.
Fire strongly impacts the composition and structure of ecosystems, with consequences yet to be understood. We used Moderate Resolution Imaging Spectroradiometer (MODIS) data to map fire frequency and fire intensity and investigate their effects on miombo woodlands (MW) of central Mozambique. Tree species diversity was evaluated and compared using rarefaction curves. Non-metric multidimensional scaling (NMDS) ordination was used to identify patterns of species composition occurrence. The indicator value index method was applied to verify the occurrence of fire indicator species. In general, tree communities responded differently to varied fire regimes. We found low tree density in Intermediate fire frequency and intensity (IfIi) (180 trees ha −1) and High-frequency and Low intensity (HfLi) (316 trees ha −1) areas. The IfIi fire regime had the lowest carbon stocks (9.1 Mg ha −1), when compared to the rest of fire regimes. The species diversity decreased as fire intensity increased. IfIi areas had the maximum species diversity. The NMDS showed a varied species composition according to fire regime. We found a strong relationship between the species diversity and composition, and the pattern of fire occurrence in each fire regime. Our results are critical in supporting fire management policies and understanding fire regimes and their effects on miombo trees' structure and composition.
Understanding the ecological role of fire in forests is essential for proper management and conservation programs. The objectives of this study were: (1) to reconstruct the history of fires in a temperate forest in Sierra Madre Occidental; and (2) to interpret the impacts of fire and climate on forest structure. Sixty tree cross-sections with fire scars were analyzed, and descriptive statistics of fire history were generated. Additionally, growth cores were analyzed, and the ages of trees of different diameter categories were calculated. The synchrony between fire history and tree establishment was determined, and precipitation and Palmer Drought Severity Index (PDSI) values were correlated with the number of trees established per year. The presence of 137 fire scars was determined, which allowed the reconstruction of 41 fire events over the period 1855–2019; however, only the period 1940–2015 was used to compare tree recruitment, as tree establishment was detected in this period. The mean fire interval (MFI) was 2.28 years in general, and 12.17 years for extensive fires. As regards vegetation, a continuous recruitment pattern was observed, typical of a frequent low-intensity fire regime, although peak regeneration occurred after extensive fires. The correlation analysis showed that the number of trees established per year was influenced by the wet conditions that occurred in December of the previous year and the dry conditions in September and October of the previous year. This finding demonstrates the historical influence of fire and climate on the structure of the current stand in the study area. Therefore, the present study highlights the importance of including fire in forest management programs, considering the natural fire regime to which the species in this ecosystem are already adapted.
1 | INTRODUCTION
Restoration of natural forests in areas previously used for monoculture plantations enhances ecological stability, biodiversity conservation, carbon sequestration and other ecosystem services (Kremer & Bauhus, 2020; Meli et al., 2017). This can either be achieved through passive or active processes (Holl & Aide, 2011). A passive process entails natural recruitment of woody species from seeds that are dispersed from the surrounding vegetation or those existing in the soil seed bank. Conversely, active restoration is a deliberate intervention that involves planting of appropriate indigenous species seedlings or seeds in an area of interest (Holl & Aide, 2011). Irrespective of the method adopted, protecting the soil seed bank, surviving indigenous plants and target sites from degradation in situ have incremental restorative impacts. The decision between active and passive restoration should take into account the ecological status of the targeted sites, distance of such areas from remnant natural forests and the potential of nearby natural forests to effectively disperse seeds to the regenerating forest (Fimbel & Fimbel, 1996; Kremer & Bauhus, 2020). Globally, there are ambitious plans to restore degraded forests by 2030, for example the Bonn Challenge
(https://www.bonnchallenge.org/), to mitigate the effects of climate change and enhance ecosystem services (Griscom et al., 2017). In Kenya, this target has been set at one million hectares of degraded forest land (Ministry of Environment and Natural Resources, 2016). However, the framework for assessing restoration progress has not yet been well developed. One of the options for assessing such gains is by comparing the restoration progress between undisturbed mature natural forests. and regenerating forests emerging in previously clear- felled mono-
culture forest stands (Curran et al., 2014; Fimbel & Fimbel, 1996).
Here, we hypothesized that the plant species composition and stand structure of a regenerating forest were similar to a nearby mature mixed-species indigenous forest in the central highlands of Kenya. We assumed the soil characteristics (pH, salinity, nitrogen, phosphorus and potassium) would differ in the two forest types due to higher turnover period of decomposition in the mature forest. The results of the study were intended to provide decision support regarding the suitability of passive and active restoration approaches in abandoned forest plantation sites.
Aims
Exploring species-genetic diversity correlation (SGDC) is essential for understanding spatial patterns of diversity and the underlying mechanisms. Until now, latitudinal patterns of species diversity (SD) and genetic diversity (GD) were rarely studied simultaneously. As the freezing-tolerance hypothesis predicts a decrease of SD from low to high latitudes and the central-marginal hypothesis predicts a unimodal pattern of GD along latitude, we hypothesized that SD and GD are uncorrelated. We also tested how climatic and edaphic factors affect the correlation between the two levels of biodiversity.
Methods
We measured (i) SD (species richness and Simpson’s diversity index) and community dissimilarity of woody plants (63 plots), (ii) GD (allelic richness and expected heterozygosity) and genetic differentiation of a dominant tree species (Euptelea pleiospermum; 678 individuals from 21 populations) using nuclear microsatellite data, and (iii) climatic (annual mean precipitation, annual mean temperature, minimum temperature, maximum temperature, annual relative moisture, solar radiation, photosynthetically active radiation) and edaphic (total C, total N, total P, available P, K, Ca, Mg, Al, Fe, Mn, Ni, Zn, B, Mo, Cu, pH) variables of 21 sites. We conducted both linear and quadratic regression analyses of diversity parameters against latitude. Relationships between SD and GD were tested using Pearson’s correlation. Pearson’s and Spearman’s ρ correlation coefficients were calculated between diversity parameters and environmental variables. We used stepwise multiple regression analysis to identify the significant environmental predictors of SD and GD.
Important Findings
We observed no significant correlation between measures of SD and GD. SD decreases with increasing latitude, which can be partly explained by the freezing-tolerance hypothesis, whereas GD presents a unimodal pattern along the latitudinal gradient, which is consistent with the prediction of the central-marginal hypothesis. The contrasting latitudinal patterns of SD and GD indicate that the two levels of biodiversity do not co-vary in space. Based on both correlation analysis and stepwise multiple regression analysis, SD is only related to climatic variables, whereas GD is mainly related to edaphic variables. Our results show that different geographical and environmental factors affect SD and GD, driving the non-significant correlation between the two fundamental levels of biodiversity. Furthermore, a significantly positive correlation was observed between genetic distance and community dissimilarity, both of which were significantly correlated with geographical distance.
Forests and forest trees have continuously been supporting human beings through the provision of food and food-associated materials, fodder and foraging sites for their livestock, and medicinal materials, as well as multiple ecological services. However, unbalanced utilization of these resources and the biotic and abiotic disturbances interrupt their sustainability and ecological functions. We studied the tree population structure, diversity, and regeneration status of tree species in the Abu Gadaf Natural Reserved Forest in 46 sample plots of 20 m x 50 m (1000 m²) distributed systematically throughout the reserve over a year. The study findings showed that highland sites have higher tree species richness (47 species) compared to lowland sites (31 species) and the highest contributors are Combretaceae (21.3%) and Fabaceae (19.2%) families. Moreover, seedlings in highland sites are twice that of lowlands, with a significant difference between the two sites (F1,46 = 138.4, p < 0.001). The same trend has been observed for saplings and adult trees (F1,46 = 143.2, p < 0.01; F1,46 = 126.7, p < 0.01, respectively). Likewise, all dendrometric parameters and diversity indices demonstrated significant differences between the sites across the reserve with lower values in the lowland sites and vigorous regeneration in the highland sites (T = 33.7, P < 0.001; T = 22.3, P = 0.001; T = 27.9, P = 0.042, respectively). The study concludes that over browsing by livestock and intensive illegal tree logging in the lowland sites have severely affected the tree population composition, which might consequently disturb the regeneration process and seedlings recruitment. A conservation action plan is urgently needed to protect vulnerable species, especially those with low importance value index.
Restoring anthropogenic footprints to pre-disturbance conditions or minimizing their long-term impacts is an important goal in conservation. Many footprints, particularly if left alone, have wide-ranging effects on biodiversity. In Canada, energy exploration footprints result in forest dissection and fragmentation contributing to declines in woodland caribou. Developing cost effective strategies to restore forests and thus conserving the woodland caribou habitat is a conservation priority. In this study, we compared the effects of wildfire and local variation in the amount of residual woody debris on natural regeneration in jack pine on exploratory well pads in Alberta’s boreal forest. Specifically, we investigated how footprint size, fire severity (overstory tree mortality), ground cover of fine and coarse woody debris, and adjacent stand characteristics (i.e., height, age, and cover), affected tree regeneration densities and height using negative binomial count and linear models (Gaussian), respectively. Regeneration density was 30% higher on exploratory well pads than adjacent forests, increased linearly with fire severity on the exploratory well pads (2.2% per 1% increase in fire severity), but non-linearly in adjacent forests (peaking at 51,000 stems/ha at 72% fire severity), and decreased with amount of woody debris on exploratory well pads (2.7% per 1% increase in woody debris cover). The height of regenerating trees on exploratory well pads decreased with fire severity (0.56 cm per 1% increase in fire severity) and was non-linearly related to coarse woody debris (peaking at 286 cm at 9.4% coarse woody debris cover). Heights of 3 and 5 m on exploratory well pads were predicted by 13- and 21-years post-fire, respectively. Our results demonstrate that wildfires can stimulate natural recovery of fire-adapted species, such as jack pine, on disturbances as large as exploratory well pads (500–1330 m2) and that the type and amount of woody debris affects these patterns.
Planted forests in South Africa have been affected by an increasing number of economically damaging fires over the past four decades. They constitute a major threat to the forestry industry and account for over 80% of the country’s commercial timber losses. Forest fires are more frequent and severe during the drier drought conditions that are typical in South Africa. For proper forest management, accurate detection and mapping of burned areas are required, yet the exercise is difficult to perform in the field because of time and expense. Now that ready-to-use satellite data are freely accessible in the cloud-based Google Earth Engine (GEE), in this study, we exploit the Sentinel-2-derived differenced normalized burned ratio (dNBR) to characterize burn severity areas, and also track carbon monoxide (CO) plumes using Sentinel-5 following a wildfire that broke over the southeastern coast of the Western Cape province in late October 2018. The results showed that 37.4% of the area was severely burned, and much of it occurred in forested land in the studied area. This was followed by 24.7% of the area that was burned at a moderate-high level. About 15.9% had moderate-low burned severity, whereas 21.9% was slightly burned. Random forests classifier was adopted to separate burned class from unburned and achieved an overall accuracy of over 97%. The most important variables in the classification included texture, NBR, and the NIR bands. The CO signal sharply increased during fire outbreaks and marked the intensity of black carbon over the affected area. Our study contributes to the understanding of forest fire in the dynamics over the Southern Cape forestry landscape. Furthermore, it also demonstrates the usefulness of Sentinel-5 for monitoring CO. Taken together, the Sentinel satellites and GEE offer an effective tool for mapping fires, even in data-poor countries.
Citation: Bhatta, K.P.; Aryal, A.; Baral, H.; Khanal, S.; Acharya, A.K.; Phomphakdy, C.; Dorji, R. Forest Structure and Composition under Contrasting Precipitation Regimes in the High Mountains, Western Nepal. Sustainability 2021, 13, 7510. https://doi.org/10.3390/su13137510
Accurate and efficient burned area mapping and monitoring are fundamental for environmental applications. Studies using Landsat time series for burned area mapping are increasing and popular. However, the performance of burned area mapping with different spectral indices and Landsat time series has not been evaluated and compared. This study compares eleven spectral indices for burned area detection in the savanna area of southern Burkina Faso using Landsat data ranging from October 2000 to April 2016. The same reference data are adopted to assess the performance of different spectral indices. The results indicate that Burned Area Index (BAI) is the most accurate index in burned area detection using our method based on harmonic model fitting and breakpoint identification. Among those tested, fire-related indices are more accurate than vegetation indices, and Char Soil Index (CSI) performed worst. Furthermore, we evaluate whether combining several different spectral indices can improve the accuracy of burned area detection. According to the results, only minor improvements in accuracy can be attained in the studied environment, and the performance depended on the number of selected spectral indices.
Australian montane sclerophyll shrubland vegetation is widely considered to be resilient to infrequent severe fire, but this may not be the case in Tasmania. Here, we report on the vegetative and seedling regeneration response of a Tasmanian non-coniferous woody montane shrubland following a severe fire, which burned much of the Great Pine Tier in the Central Plateau Conservation Area during the 2018–2019 fire season when a historically anomalously large area was burned in central Tasmania. Our field survey of a representative area burned by severe crown fire revealed that more than 99% of the shrubland plants were top-killed, with only 5% of the burnt plants resprouting one year following the fire. Such a low resprouting rate means the resilience of the shrubland depends on seedling regeneration from aerial and soil seedbanks or colonization from plants outside the burned area. Woody species’ seedling densities were variable but generally low (25 m−2). The low number of resprouters, and reliance on seedlings for recovery, suggest the shrubland may not be as resilient to fire as mainland Australian montane shrubland, particularly given a warming climate and likely increase in fire frequency.
A methodology to estimate the extent of areas affected by forest fires, as well as the burn severity levels using Sentinel 2 images (10 and 20 m) is proposed and applied to the fires occurred in October 2017 in Spain and Portugal. An extension larger than 250,000 ha and 4 burn severity levels (low, moderate, high and very high) have been obtained. The comparison with the European Forest Fire Information System (EFFIS), which uses MODIS images (250 m), shows that the methodology improves the area estimate by 10 % in commission area. In terms of burn severity levels, the Separability index (SI) and the Kappa statistic (k) show a high correlation between Sentinel-2 and EFFIS (SI values higher than one in all cases and k higher than 0.69, respectively).
Vegetation fires are an essential component of the Earth system but can also cause substantial economic losses, severe air pollution, human mortality and environmental damage. Contemporary fire regimes are increasingly impacted by human activities and climate change, but, owing to the complex fire–human–climate interactions and incomplete historical or long-term datasets, it is difficult to detect and project fire-regime trajectories. In this Review, we describe recent global and regional trends in fire activity and examine projections for fire regimes in the near future. Although there are large uncertainties, it is likely that the economic and environmental impacts of vegetation fires will worsen as a result of anthropogenic climate change. These effects will be particularly prominent in flammable forests in populated temperate zones, the sparsely inhabited flammable boreal zone and fire-sensitive tropical rainforests, and will contribute to greenhouse gas emissions. The impacts of increased fire activity can be mitigated through effective stewardship of fire regimes, which should be achieved through evidence-based fire management that incorporates indigenous and local knowledge, combined with planning and design of natural and urban landscapes. Increasing transdisciplinary research is needed to fully understand how Anthropocene fire regimes are changing and how humans must adapt.
Wildfires are currently one of the most important environmental problems, as they cause disturbance in ecosystems generating environmental, economic and social costs. The Sentinel-2 from Copernicus Program (Sentinel satellites) offers a great tool for post-fire monitoring. The main objective of this study is to evaluate the potential of Sentinel-2 in a peculiar mountainous landscape by measuring and identifying the burned areas and monitor the short-term response of the vegetation in different ‘burn severity’ classes. A Sentinel-2 dataset was created, and pre-processing operations were performed. Relativized Burn Ratio (RBR) was calculated to identify ‘burn scar’ and discriminate the ‘burn severity’ classes. A two-year monitoring was carried out with areas identified based on different severity classes, using Normalized Difference Vegetation Index (NDVI) to investigate the short-term vegetation dynamics of the burned habitats; habitats refer to Annex I of the European Directive 92/43/EEC. The study area is located in ‘Campo Imperatore’ within the Gran Sasso – Monti della Laga National Park (central Italy). The first important result was the identification and quantification of the area affected by fire. The RBR allowed us to identify even the less damaged habitats with high accuracy. The survey highlighted the importance of these Open-source tools for qualitative and quantitative evaluation of fires and the short-term assessment of vegetation recovery dynamics. The information gathered by this type of monitoring can be used by decision-makers both for emergency management and for possible environmental restoration of the burned areas.
In Mediterranean countries, in the year 2017, extensive surfaces of forests were damaged by wildfires. In the Vesuvius National Park, multiple summer wildfires burned 88% of the Mediterranean forest. This unprecedented event in an environmentally vulnerable area suggests conducting spatial assessment of the mixed-severity fire effects for identifying priority areas and support decision-making in post-fire restoration. The main objective of this study was to compare the ability of the delta Normalized Burn Ratio (dNBR) spectral index obtained from Landsat-8 and Sentinel-2A satellites in retrieving burn severity levels. Burn severity levels experienced by the Mediterranean forest communities were defined by using two quali-quantitative field-based composite burn indices (FBIs), namely the Composite Burn Index (CBI), its geometrically modified version CBI (GeoCBI), and the dNBR derived from the two medium-resolution multispectral remote sensors. The accuracy of the burn severity map produced by using the dNBR thresholds developed by Key and Benson (2006) was first evaluated. We found very low agreement (0.15 < K < 0.21) between the burn severity class obtained from field-based indices (CBI and GeoCBI) and satellite-derived metrics (dNBR) from both Landsat-8 and Sentinel-2A. Therefore, the most appropriate dNBR thresholds were rebuilt by analyzing the relationships between two field-based (CBI and GeoCBI) and dNBR from Landsat-8 and Sentinel-2A. By regressing alternatively FBIs and dNBRs, a slightly stronger relationship between GeoCBI and dNBR metrics obtained from the Sentinel-2A remote sensor (R2 = 0.69) was found. The regressed dNBR thresholds showed moderately high classification accuracy (K = 0.77, OA = 83%) for Sentinel-2A, suggesting the appropriateness of dNBR-Sentinel 2A in assessing mixed-severity Mediterranean wildfires. Our results suggest that there is no single set of dNBR thresholds that are appropriate for all burnt biomes, especially for the low levels of burn severity, as biotic factors could affect satellite observations.
Historical analysis of wildfire frequency, intensity, size, season, and type helps to determine the fire regime and the impacts of human activity in a region. Information about the temporal and spatial distribution of forest fires can help guide the formulation of integrated fire management policies. Mt Kenya Forest provides ecosystem services that sustain the livelihoods of local communities. However, forest fires have negatively affected sustainability of these services. This study describes recent fire patterns in the Mt Kenya forest. Field observations recorded by the Kenya Forest Service from 1980 to 2015 are analyzed. In addition, trends in fire occurrence over time and in relation to vegetation type are described. Key findings evidence a fire-prone period in February and March and a decrease of total burned area during the study period. Bush and grassland were the most fire-prone vegetation, and the fire regime varied in each forest station. Further, field observations were compared with satellite data. Some discrepancies between the field and satellite fire data were observed, especially for larger fires. These findings confirm the importance of monitoring efforts by the Kenya Forest Service to inform wildfire management. Recommendations are made on ways to improve fire monitoring and fire suppression efforts.
The combination of direct human influences and the effects of climate change are resulting in altered ecological disturbance regimes, and this is especially the case for wildfires. Many regions that historically experienced low–moderate severity fire regimes are seeing increased area burned at high severity as a result of interactions between high fuel loads and climate warming with a number of negative ecological effects. While ecosystem impacts of altered fire regimes have been examined in the literature, little is known of the effects of changing fire regimes on forest understory plant diversity even though understory taxa comprise the vast majority of forest plant species and play vital roles in overall ecosystem function. We examined understory plant diversity across gradients of wildfire severity in eight large wildfires in yellow pine and mixed conifer temperate forests of the Sierra Nevada, California, USA. We found a generally unimodal hump‐shaped relationship between local (alpha) plant diversity and fire severity. High‐severity burning resulted in lower local diversity as well as some homogenization of the flora at the regional scale. Fire severity class, post‐fire litter cover, and annual precipitation were the best predictors of understory species diversity. Our research suggests that increases in fire severity in systems historically characterized by low and moderate severity fire may lead to plant diversity losses. These findings indicate that global patterns of increasing fire size and severity may have important implications for biodiversity.
Distribution patterns of biodiversity and the factors influencing them are important in conservation and management strategies of natural resources. With impending threats from increased human population and global climatic changes, there is an urgent need for a comprehensive understanding of these patterns, more so in species-rich tropical montane ecosystems where little is known about plant diversity and distribution. Vascular species richness along elevation and climatic gradients of Aberdare ranges forest were explored. A total of 1337 species in 137 families, 606 genera, 82 subspecies and 80 varieties were recorded. Correlations, simple linear regression and Partial least square regression analysis were used to assess richness and diversity patterns of total plants, herbs, shrubs, climbers, arboreal and endemic species from 2000–4000 m above sea level. Total plant species richness showed a monotonic declining relationship with elevation with richness maxima at 2000–2100 m a.s.l., while endemic species richness had a positive unimodal increase along elevation with peaks at 3600–3700 m a.s.l. Herbs, shrubs, climbers and arboreal had significant negative relationships with altitude, excluding endemism which showed positive relations. In contrast, both air and soil temperatures had positive relationships with taxa richness groups and negative relations with endemic species. Elevation was found to have higher relative influence on plant richness and distribution in Aberdare ranges forest. For effective conservation and management of biodiversity in Aberdare, localized dynamic conservation interventions are recommended in contrast to broad and static strategies. Establishment of conservation zones and migration corridors are necessary to safeguard biodiversity in line with envisaged global climatic vicissitudes.
Satellite data play a major role in supporting knowledge about fire severity by delivering rapid information to map fire-damaged areas in a precise and prompt way. The high availability of free medium-high spatial resolution optical satellite data, offered by the Copernicus Programme, has enabled the development of more detailed post-fire mapping. This research study deals with the exploitation of Sentinel-2 time series to map burned areas, taking advantages from the high revisit frequency and improved spatial and spectral resolution of the MSI optical sensor. A novel procedure is here presented to produce medium-high spatial resolution burned area mapping using dense Sentinel-2 time series with no a priori knowledge about wildfire occurrence or burned areas spatial distribution. The proposed methodology is founded on a threshold-based classification based on empirical observations that discovers wildfire fingerprints on vegetation cover by means of an abrupt change detection procedure. Effectiveness of the procedure in mapping medium-high spatial resolution burned areas at the national level was demonstrated for a case study on the 2017 Italy wildfires. Thematic maps generated under the Copernicus Emergency Management Service were used as reference products to assess the accuracy of the results. Multitemporal series of three different spectral indices, describing wildfire disturbance, were used to identify burned areas and compared to identify their performances in terms of spectral separability. Result showed a total burned area for the Italian country in the year 2017 of around 1400 km2, with the proposed methodology generating a commission error of around 25% and an omission error of around 40%. Results demonstrate how the proposed procedure allows for the medium-high resolution mapping of burned areas, offering a benchmark for the development of new operational downstreaming services at the national level based on Copernicus data for the systematic monitoring of wildfires.
Mount Kenya is one of Kenya’s ‘water towers’, the headwaters for the country’s major rivers including the Tana River and Ewaso Nyiro River, which provide water and hydroelectric power to the semiarid region. Fires affect water downstream, but are difficult to monitor given limited resources of local land management agencies. Satellite-based remote sensing has the potential to provide long term coverage of large remote areas on Mount Kenya, especially using the free Landsat data archive and moderate resolution imaging spectroradiometer (MODIS) fire products. In this study, we mapped burn scars on Mount Kenya using 30 m Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI) derived dNBR (change in normalized burn ratio) and MODIS active fire detection and burned area data for fires occurring from 2004 to 2015. We also analyzed topographic position (elevation, slope, aspect) of these fires using an ASTER global digital elevation model (GDEM v2) satellite-derived 30 m digital elevation model (DEM). Results indicate that dNBR images calculated from data acquired about one year apart were able to identify large fires on Mount Kenya that match locations (and timing) of MODIS active fire points and burned areas from the same time period, but we were unable to detect smaller and/or older fires.
African landscape fires are widespread, recurrent and temporally dynamic. They burn large areas of the continent, modifying land surface properties and significantly affect the atmosphere. Satellite Earth Observation (EO) data play a pivotal role in capturing the spatial and temporal variability of African biomass burning, and provide the key data required to develop fire emissions inventories. Active fire observations of fire radiative power (FRP, MW) have been shown to be linearly related to rates of biomass combustion (kg s−1). The Meteosat FRP-PIXEL product, delivered in near real-time by the EUMETSAT Land Surface Analysis Satellite Applications Facility (LSA SAF), maps FRP at 3 km resolution and 15-min intervals and these data extend back to 2004. Here we use this information to assess spatio-temporal variations in fire activity across sub-Saharan Africa, and identify an overall trend of decreasing annual fire activity and fuel consumption, agreeing with the widely-used Global Fire Emissions Database (GFEDv4) based on burned area measures. We provide the first comprehensive assessment of relationships between per-fire FRE-derived fuel consumption (Tg dry matter, DM) and temporally integrated Moderate Resolution Imaging Spectroradiometer (MODIS) net photosynthesis (PSN) (Tg, which can be converted into pre-fire fuel load estimates). We find very strong linear relationships over southern hemisphere Africa (mean r = 0.96) that are partly biome dependent, though the FRE-derived fuel consumptions are far lower than those derived from the accumulated PSN, with mean fuel consumptions per unit area calculated as 0.14 kg DM m−2. In the northern hemisphere, FRE-derived fuel consumption is also far lower and characterized by a weaker linear relationship (mean r = 0.76). Differences in the parameterization of the biome look up table (BLUT) used by the MOD17 product over Northern Africa may be responsible but further research is required to reconcile these differences. The strong relationship between fire FRE and pre-fire fuel load in southern hemisphere Africa is encouraging and highlights the value of geostationary FRP retrievals in providing a metric that relates very well to fuel consumption and fire emission variations. The fact that the estimated fuel consumed is only a small fraction of the fuel available suggests underestimation of FRE by Spinning Enhanced Visible and Infrared Imager (SEVIRI) and/or that the FRE-to-fuel consumption conversion factor of 0.37 MJ kg−1 needs to be adjusted for application to SEVIRI. Future geostationary imaging sensors, such as on the forthcoming Meteosat Third Generation (MTG), will reduce the impact of this underestimation through its ability to detect even smaller and shorter-lived fires than can the current second generation Meteosat.
This paper proposes an Integrated Fire Management (IFM) framework that can be used to support communities and resource managers in finding effective and efficient approaches to prevent damaging fires, as well as to maintain desirable fire regimes in Kenya. Designing and implementing an IFM approach in Kenya calls for a systematic understanding of the various uses of fire and the underlying perceptions and traditional ecological knowledge of the local people. The proposed IFM framework allows different stakeholders to evaluate the risks posed by fires and balance them with their beneficial ecological and economic effects making it easier for them to develop effective fire management approaches. A case study of the proposed IFM framework was conducted in Gathiuru Forest, which that is part of the larger Mt. Kenya Forest Ecosystem. Focus group discussions were held with key resource persons, primary and secondary data on socio-economic activities was studied, fire and weather records were analysed and the current fire management plans were consulted. Questionnaires were used to assess how the IFM is implemented in the Gathiuru Forest Station. The results show that the proposed IFM framework is scalable and can be applied in places with fire-dependent ecosystems as well as in places with fire-sensitive ecosystems in Kenya. The effectiveness of the proposed IFM framework depends on the active participation, formulation and implementation of the IFM activities by the main stakeholder groups (Kenya Forest Service (KFS), Kenya Wildlife Service (KWS), and the Community Forest Associations (CFA). The proposed IFM framework helps in implementing cost-effective approaches to prevent damaging fires and maintain desirable fire regimes in Kenya.
Landscape fires occur on a large scale in (sub)tropical savannas and
grasslands, affecting ecosystem dynamics, regional air quality and
concentrations of atmospheric trace gasses. Fuel consumption per unit of area
burned is an important but poorly constrained parameter in fire emission
modelling. We combined satellite-derived burned area with fire radiative
power (FRP) data to derive fuel consumption estimates for land cover types
with low tree cover in South America, Sub-Saharan Africa, and Australia. We
developed a new approach to estimate fuel consumption, based on FRP data from
the polar-orbiting Moderate Resolution Imaging Spectroradiometer (MODIS) and
the geostationary Spinning Enhanced Visible and Infrared Imager (SEVIRI) in
combination with MODIS burned-area estimates. The fuel consumption estimates
based on the geostationary and polar-orbiting instruments showed good
agreement in terms of spatial patterns. We used field measurements of fuel
consumption to constrain our results, but the large variation in fuel
consumption in both space and time complicated this comparison and absolute
fuel consumption estimates remained more uncertain. Spatial patterns in fuel
consumption could be partly explained by vegetation productivity and fire
return periods. In South America, most fires occurred in savannas with
relatively long fire return periods, resulting in comparatively high fuel
consumption as opposed to the more frequently burning savannas in Sub-Saharan
Africa. Strikingly, we found the infrequently burning interior of Australia
to have higher fuel consumption than the more productive but frequently
burning savannas in northern Australia. Vegetation type also played an
important role in explaining the distribution of fuel consumption, by
affecting both fuel build-up rates and fire return periods. Hummock grasslands,
which were responsible for a large share of Australian biomass burning,
showed larger fuel build-up rates than equally productive grasslands in
Africa, although this effect might have been partially driven by the presence
of grazers in Africa or differences in landscape management. Finally, land
management in the form of deforestation and agriculture also considerably
affected fuel consumption regionally. We conclude that combining FRP and
burned-area estimates, calibrated against field measurements, is a promising
approach in deriving quantitative estimates of fuel consumption. Satellite-derived fuel consumption estimates may both challenge our current
understanding of spatiotemporal fuel consumption dynamics and serve as
reference datasets to improve biogeochemical modelling approaches. Future
field studies especially designed to validate satellite-based products, or
airborne remote sensing, may further improve confidence in the absolute fuel
consumption estimates which are quickly becoming the weakest link in fire
emission estimates.
Vegetation burning is a global environmental threat that results in local ecological, economic
and social impacts but also has large-scale implications for global change. The burning is usually a
result of interacting factors such as climate, land use and vegetation type. Despite its importance as
a factor shaping ecological, economic and social processes, countries highly vulnerable to climate
change in Central America, such as El Salvador, lack an assessment of this complex relationship.
In this study we rely on remotely sensed measures of the Normalized Vegetation Difference Index
(NDVI) and thermal anomaly detections by the Moderate Resolution Imaging Spectroradiometer
(MODIS) sensor to identify vegetation cover changes and fire occurrences. We also use land use data
and rainfall observations derived from the Tropical Rainfall Measuring Mission (TRMM) data to
determine the spatial and temporal variability and interactions of these factors. Our results indicate
a highly marked seasonality of fire occurrence linked to the climatic variability with a peak of fire
occurrences in 2004 and 2013. Low vegetation indices occurred in March–April, around two months
after the driest period of the year (December–February), corresponding to months with high detection
of fires. Spatially, 65.6% of the fires were recurrent and clustered in agriculture/cropland areas and
within 1 km of roads (70%) and only a 4.7% of fires detected were associated with forests. Remaining
forests in El Salvador deserve more attention due to underestimated consequences of forest fires.
The identification of these clear patterns can be used as a baseline to better shape management
of fire regimes and support decision making in this country. Recommendations resulting from
this work include focusing on fire risk models and agriculture fires and long-term ecological and
economic consequences of those. Furthermore, El Salvador will need to include agricultural fires in
the contribution to national accounts emissions.
The Invasive Species Specialist Group (ISSG) is a global network of scientific and policy experts on invasive species, organized under the auspices of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN). ISSG aims to reduce threats to natural ecosystems and the native species they contain by increasing awareness of invasive alien species, and of ways to prevent, control or eradicate them. Since its establishment, over two decades ago, ISSG has taken the lead on collating, managing and disseminating global invasive species information, promoting practitioner networks and supporting development of policy and regulation aimed at reducing the insidious threat of biological invasions. All this has been accomplished through the development of knowledge products (such as the Global Invasive Species Database (GISD)), promoting dynamic networks such as Aliens-L, advocacy and publications. ISSG has actively catered to emerging needs with activities directed at key areas such as islands, threatened species, protected areas and developing invasive species indicators to support prioritising and monitoring management action. ISSG is working with partners advancing the adoption of a standardised framework of pathway categories and developing criteria for the ranking of known invasive species based on the type and magnitude of impacts. ISSG through participation in the Global Invasive Alien Species Information Partnership (GIASIPartnership) is working with other information providers supporting countries with current and authoritative information to effectively implement Article 8(h), Aichi Biodiversity Target 9 and other related decisions of the Convention on Biological Diversity (CBD) and other Multilateral Environmental Agreements (MEAs) such as the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and the Ramsar Convention on Wetlands.
A study was conducted to determine the impacts of soil disturbance and compaction on soil physical properties and tree growth, and the effectiveness of tillage in maintaining or enhancing site productivity for intensively managed Pinus kesiya Royle ex Gordon sites in Dedza, Malawi. The results indicate that about fifty two percent of the area of compacted plots was affected by the vehicular traffic. Seventy percent of the trees of the trees were planted on microsites with some degree of soil disturbance. Soil bulk density at 0 – 20 cm depth increased from 0.45 to 0.66 Mg m-3 in the most compacted portions of traffic lanes. Soil strength in traffic lanes increased at all 60 cm depth but never exceeded 1200 kPa. Volumetric soil water content in compacted traffic lanes was greater than that in non-compacted soil. Total soil porosity decreased 13.8% to 16.1% with compaction, while available water holding capacity increased. The study revealed no detrimental effects on tree height and diameter from soil disturbance or compaction throughout the three growing season. At the ages of two and three, a tree volume index was actually greater for trees planted on traffic lanes than those on non-disturbed soil.
We determine the aboveground biomass and carbon storage (ABGC) of trees and the herbaceous layer in miombo woodland in the Eastern Arc Mountains (EAM) of Tanzania. In four 1-ha sample plots in Nyanganje and Kitonga Forests, we measured all trees ≥10 cm diameter alongside height and wood mass density. The plots contained an average of 20 tree species ha⁻¹ (range 11–29) and 344 stems ha⁻¹ (range 281–382) with Shannon diversity values of 1.05 and 1.25, respectively. We weighted nine previously published woody savannah allometric models based on whether: (i) the model was derived from the same geographical region; (ii) the model included tree height/wood mass density in addition to stem diameter; and (iii) sample size was used to fit the model. The weighted mean ABGC storage from the nine models range from 13.5 ± 2 to 29.8 ± 5 Mg ha⁻¹. Measured ABGC storage in the herbaceous layer, using the wet combustion method, adds 0.55 ± 0.02 Mg C ha⁻¹. Estimates suggest that EAM miombo woodlands store a range of 13–30 Mg ha⁻¹ of carbon. Although the estimates suggest that miombo woodlands store significant quantities of carbon, caution is required as this is the first estimate based on in situ data.
Surveying Savannas
Savannas are structurally similar across the three major continents where they occur, leading to the assumption that the factors controlling vegetation structure and function are broadly similar, too. Lehmann et al. (p. 548 ) report the results of an extensive analysis of ground-based tree abundance in savannas, sampled at more than 2000 sites in Africa, Australia, and South America. All savannas, independent of region, shared a common functional property in the way that moisture and fire regulated tree abundance. However, despite qualitative similarity in the moisture–fire–tree-biomass relationships among continents, key quantitative differences exist among the three regions, presumably as a result of unique evolutionary histories and climatic domains.
on cypress plantations in Kenya. Practical adherence to the recommended thinning and cutting practices and their effects on the development of Cupressus lusitanica (cypress) plantations in Kiambu District, Kenya in terms of total volume and value yields, and distribution of trees and volume to diameter classes are examined. Data were collected from 27 plantations aged between 3 and 26 y in Kiambu District during the period August-November 1984. Although the original plan was to collect data from the plantations which had attained the rotation age (30 y ), it was not possible to do so because the plantations were clearfelled much earlier - mostly between 24 and 26 y. Analysis of the data showed that the recommended thinning and cutting practices were not adhered to. MUCHIRI, M.N. 1993. Kesan penyisihan dari amalan penjarangan yang disyorkan diladang cypress di Kenya. Penelitian telah dibuat terhadap amalan penjarangan dan penebangan yang disyorkan dan kesannya kepada pembangunan ladang-ladang Cupressus lusitanica (cypress) di Daerah Kiambu, Kenya, dari segi jumlah isipadu dan nilai hasil, dan taburan pokok dan isipadu buah kelas-kelas diameter dikaji. Data dikumpul dari 27 ladang-ladang berumur diantara 3 hingga 26 tahun dalam jangkamasa Ogos hingga November 1984. Walaupun pada cadangan asal hanya data dari ladang-ladang yang telah mencapai giliran pusingan 30 tahun, ianya tidak mungkin kerana ladang tersebut ditebang habis lebih awal, kebanyakanya antara 24- 26 tahun. Analisis data menunjukkan amalan penjarangan dan penebangan yang disyorkan tidak dipatuhi.
The objective of this study was to investigate the effects of repeated dry season annual hot fires on woody plants in a semiarid southern African savanna in Zimbabwe. Parts of the National University of Science and Technology (NUST) research fields in Bulawayo, Zimbabwe have been burnt annually in the dry season between 1994 and 2003 in order to control bush encroachment. The present study was carried out in both the burnt and unburnt sites of the NUST research fields consisting of Acacia karroo-Colophospermum mopane vegetation. The study adopted a randomised block design and woody vegetation data were collected from a total of 10 plots. Variables measured and recorded included woody plant height, density, number of stems per plant, proportion of multistemmed plants, proportion of dead stems, basal area, fire damage and number of species per plot. The study results indicate that there were significant differences (P < 0.05) in woody plant heights, proportion of multistemmed plants, proportion of dead stems and basal areas between the burnt and unburnt sites. However, there were no significant differences (P > 0.05) in density, number of species per plot and number of stems per plant in woody plants between the burnt and unburnt sites. The study results suggest that repeated dry season annual hot fires leads to thinner and shortstemmed plants in semiarid savanna ecosystems. Repeated burning also increased the proportion of multistemmed plants and proportion of dead stems in the burnt site. Despite burning sections of the study area annually, bush encroachment control has not been effectively achieved. The study findings points to the need of adaptive management strategies in the use of fires in managing vegetation in semiarid savanna ecosystems.
An accidental fire that affected vegetation across an elevational gradient on the eastern slope of Mount Muhabura in Volcanoes National Park (Rwanda) provided a unique opportunity to compare the richness, diversity, composition and elevational distribution of plant taxa across burned and unburned Afromontane habitats 1 and 9 years after the fire. Although richness and local α‐diversity were comparable, community composition differed across burned and unburned habitats with the former having a lower cover of woody perennials and a higher cover of herbaceous annuals. We confirm the role of fire in shaping Afromontane vegetation, which is important information for protected area management.
The Eastern Arc Mountains are one of the most important ecosystems that conserve biodiversity in the world. These ecosystems are threatened by the increasing occurrence of wildfires. Nevertheless, there is inadequate information useful for the development of effective strategies to prevent or respond to future fires. This paper analyses the current extent of dry season fires, underlying causes and the effectiveness of the fire management strategy being implemented in and around the Uluguru Nature Forest Reserve (UNFR) between 2016 and 2021. Differenced Normalised Burn Ratio derived from Landsat satellite images was applied to determine the extent of burned areas, and focus group discussions were held to determine the underlying causes of fires and the extent of implementation of fire management strategies. About 2% (472 ha) of reserved UNFR and 5% (2,854 ha) of unreserved forests were burned in 2017. Some of the fires impacted on 60% (370 ha) of the grassy Lukwangule plateau, which is home to a fire‐sensitive endemic species. The underlying causes of fires varied spatially across the mountains but generally, fire escaping from farm preparation and hunting activities were found to be the most prevalent. On average, survey participants perceived that fire management strategy objectives were achieved by only 29% mainly constrained by a shortage of financial and human resources. Our findings suggest that ignitions and fire spread in UNFR could be prevented or controlled through sustainable funding of fire management activities and the effective engagement of local communities in the management of the reserve.
In the Mediterranean Basin, changes in climate and fire regime (increased recurrence
and severity) reduce ecosystem services after wildfires by increasing soil degradation and losses in plant diversity. Our study was a biological approach to relate soil properties to vegetation recovery and burn severity. We focused our study on the natural recovery of the soil-plant interphase in Pinus halepensis Mill. forests located in the SE of Iberian Peninsula, a semiarid climate. We included some chemical properties 3 years after fire (available phosphorus (P) and soil organic carbon (Corg), among others), and biological soil indicators 3 and 5 years after fire (i.e. basal soil respiration (BSR), microbial biomass carbon (Cmic), carbon mineralization coefficient (Cmineral), metabolic quotient (qCO2) and microbial quotient (Cmic:Corg)). We analyzed the activity of three different enzymes: urease (UR), phosphatase (PHP) and β-glucosidase (GLU). The changes in most chemical properties were ephemeral, but P and Corg showed higher values in burned areas, and the highest were found for low-moderate severity. Plant recovery was the triggering factor for the recovery of Corg and biological soil function. Burn severity and time after fire influenced Cmic and the Cmic:Corg, which were higher for moderate-high severity 3 years later, but were below the unburned values 5 years after fire. The microbial activities of GLU and UR were recovered in burned areas 5 years after fire. The PHP values lowered according to higher burn severity and time after fire. The soil ecological trends obtained by a principal component analysis revealed a relationship linking GLU, BSR and qCO2 that explained soil response to burn severity. PHP, Cmic and Cmic:Corg explained most of the
variability related to time after fire. Our results provide insights into how burn severity, in Mediterranean fire-prone Aleppo pine stands, modulated the natural plant recovery linked to soil biochemical and microbiological response to fire. High burn severity limited natural vegetation recovery, and both reduced biological soil functionality. This knowledge can be implemented in post-fire planning to apply post-fire management (for mitigation and restoration) in which the “no intervention” tool should be contemplated. These findings provide information to be applied in adaptive forest management to improve the resilience of vulnerable ecosystems and to reduce burn severity in future fire events.
he main purpose of this study is to explore the relationship between three field-based fire severity indices (Composite Burn Index-CBI, Geometrically structure CBI, weighted CBI) and spectral indices derived from Sentinel 2A and Landsat-8 OLI imagery on a recent large fire in Thasos, Greece. We employed remotely sensed indices previously used from the remote sensing fire community (Normalized Difference Vegetation Index (NDVI), Normalized Burn Ratio (NBR), differenced NDVI, differenced NBR, relative differenced NBR, Relativized Burn Ratio) and seven Sentinel 2A-specific indices considering the availability of spectral information recorded in the red-edge spectral region. The statistical correlation indicated a slightly stronger relationship between the differenced NBR and the GeoCBI for both Sentinel 2A (r = 0.872) and Landsat-8 OLI (r = 0.845) imagery. Predictive local thresholds of dNBR values showed slightly higher classification accuracy for Sentinel 2A (73.33%) than Landsat-8 OLI (71.11%), suggesting the adequacy of Sentinel 2A for forest fire severity assessment and mapping in Mediterranean pine ecosystems. The evaluation of the classification thresholds calculated in this study over other fires with similar pre-fire conditions could contribute in the operational mapping and reconstruction of the historical patterns of fire severity over the Eastern Mediterranean region.
Tropical alpine areas serve important roles in the areas of biodiversity, hydrology, and carbon storage. These unique ecosystems are threatened by climate change and fire. Mount Kenya is one such area that has been faced by numerous large fires in recent years. The extent and patterning of these fires is analyzed in this study. Fires for the last 16 years were mapped with satellite imagery to create a fire history map and determine the current fire regime for the mountain. In addition, the major moorland fires over this period were mapped for severity using a spectral index. The results show that fire is a dominant force in Mount Kenya burning over 10% of the mountain in the past 16 years, and 33% of the alpine moorland areas. The fires are concentrated in the lower moorland just above the treeline, and likely play a role in determining the position of the treeline. The severity of the fires is largely low to moderate. There is no clear trend in fire quantity over this period, but the seasonality appears to have shifted from a bimodal pattern to a unimodal pattern. Also the inter-annual variability has increased considerably in the past few years. It is not clear how the vegetation, and in particular the Ericaceous vegetation which characterizes these moorlands, will respond to changing fire patterns.
Increasing wildfire activity in recent decades, partially related to extended droughts, along with concern over potential impacts of future climate change on fire activity has resulted in increased attention on fire–climate interactions. Findings from studies published in recent years have remarkably increased our understanding of fire–climate interactions and improved our capacity to delineate probable future climate change and impacts. Fires are projected to increase in many regions of the globe under a changing climate due to the greenhouse effect. Burned areas in the western US could increase by more than 50% by the middle of this century. Increased fire activity is not simply an outcome of the changing climate, but also a participant in the change. Smoke particles reduce overall solar radiation absorbed by the Earth’s atmosphere during individual fire events and fire seasons, leading to regional climate effects including reduction in surface temperature, suppression of cloud and precipitation, and enhancement of climate anomalies such as droughts. Black carbon (BC) in smoke particles displays some different radiation and climate effects by warming the middle and lower atmosphere, leading to a more stable atmosphere. BC also plays a key role in the smoke-snow feedback mechanism. Fire emissions of CO2, on the other hand, are an important atmospheric CO2 source and contribute substantially to the global greenhouse effect. Future studies should generate a global picture of all aspects of radiative forcing by smoke particles. Better knowledge is needed in space and time variability of smoke particles, evolution of smoke optical properties, estimation of smoke plume height and vertical profiles and their impacts on locations of warming layers, stability structure, clouds and smoke transport, quantification of BC emission factors and optical properties from different forest fuels, and BC’s individual and combined roles with organic carbon. Finally, understanding the short- and long-term greenhouse effect of fire CO2 emissions, increased capacity to project future fire trends (especially mega-fires), with consideration of climate–fuel–human interactions, and improved fire weather and climate prediction skills (including exploring the SST-fire relations) remain central knowledge needs.
Modelling wildfire risk using GIS and Analytical Hierarchy Process (AHP) in Aberdare afromontane forest ranges, Kenya
- Kigomo
Distribution of illegal activities and tree species poaching in Aberdare
- Nduguta
Impacts of disasters on forests
- Robinne
Effects of fire on woody vegetation structure in African savanna
- Smit
How does fire intensity and frequency affect miombo woodland tree populations and biomass?
- Ryan
The Vegetation of the Aberdare National Park Kenya
- K Schmitt
S2ToolBox Level 2 products: LAI, FAPAR, FCOVER - Version 1.1. Sentinel2 ToolBox Level2 Products
- M Weiss
- F Baret