Monitoring fire regimes and assessing their driving factors in Central Asia

Relatively little is known about fire regimes in grassland and cropland in Central Asia.In this study,eleven variables of fire regimes were measured from 2001 to 2019 by utilizing the burned area and active fire product,which was obtained and processed from the GEE(Google Earth Engine)platform,to describe the incidence,inter-annual variability,peak month and size of fire in four land cover types(forest,grassland,cropland and bare land).Then all variables were clustered to define clusters of fire regimes with unique fire attributes using the K-means algorithm.Results showed that Kazakhstan(KAZ)was the most affected by fire in Central Asia.Fire regimes in cropland in KAZ had the frequent,large and intense characters,which covered large burned areas and had a long duration.Fires in grassland mainly occurred in central KAZ and had the small scale and high-intensity characters with different quarterly frequencies.Fires in forest were mainly distributed in northern KAZ and eastern KAZ.Although fires in grassland underwent a shift from more to less frequent from 2001 to 2019 in Central Asia,vigilance is needed because most fires in grassland occur suddenly and cause harm to humans and livestock.

Short term effects of fire intensity and fire regime on vegetation dynamic in a tropical humid savanna(Lamto,central Cote d’Ivoire)

We tested the effects of different fire regimes (with different fire date and fuel load) on grass growth, tree debarking and topkill in a Guinea savanna of West Africa. Different fire intensities were simulated on two plots of 3.72 ha each, delimited in two shrubby savanna of the Lamto reserve (C?te d’Ivoire). Two fire regimes were applied, the mid-season fire (January) and the late fire (April). Two fuel levels (single: C1 and double: C2) have been used. For each fire regime, fire intensity was determined. It increases with the fuel quantity (1259 ± 356 kW·m–1 and 3380 ± 1472 kW·m–1 respectively for C1 and C2). The regrowth speed of grasses is also dependent on the fuel quantity (grasses). It increases with it and is higher after the mid-season fire than the late fire. The average intensity of the mid-season fire (2966 ± 2233 kW·m–1) is not significantly different from that of the late fire (1673 ± 1124 kW·m–1). Damages or debarking caused by fire on adult trees were recorded and are linked to fire intensity. Those damages appear to initiate the external cavity observed on trees, known to be detrimental to tree trunk mechanical resistance. They generally affect adult trees of Crossopteryx febrifuga species which is also the most commonly hollowed species. Mid-season fire remains the recommanded fire regime because it insures a faster regrowth of grasses which leads to the maintenance of equilibrium between grasses and trees.

Trends in Global and Mexico Research in Wildfires: A Bibliometric Perspective

In the last two decades, unprecedented changes have taken place in the frequency and severity of wildfires;in different regions of the world, some fires were even classified as megafires. Although there are studies about the diverse effects of fire, which have made significant theoretical contributions, a comprehensive review of the changes in fire research is required to understand worldwide patterns, particularly in those countries where fire activity is on the rise, such is the case of Mexico. The objective of this study was to analyze the trends in the research on wildfires published in Mexico and worldwide over a 40-year timescale. For this purpose, the Web of Science database, bibliometric tools, and the keywords TI = Forest fire* OR TI = Wildfire* were used to extract as many articles as possible related to fires from 1980 to 2020, without being restricted to those studies whose title included any of the variants of the keywords. There were 8458 publications about fires in the vegetation cover, with a notable increase in the frequency of studies in the previous decade;52% of the studies were concentrated in five countries and 20% of the articles focused on the study of different aspects of the soil. Mexico ranks thirteenth in volume of scientific production and studies in the country have focused mainly on the description of the quantitative relationship between the size of the affected area and the number of occurrences in the landscape, meanwhile, studies on fires and the consequences on the biotic interactions have been little explored.

Climate and fire drivers of forest composition and openness in the Changbai Mountains since the Late Glacial

Ongoing climate changes have a direct impact on forest growth;they also affect natural fire regimes,with further implications for forest composition.Understanding of how these will affect forests on decadal-to-centennial timescales is limited.Here we use reconstructions of past vegetation,fire regimes and climate during the Holocene to examine the relative importance of changes in climate and fire regimes for the abundance of key tree species in northeastern China.We reconstructed vegetation changes and fire regimes based on pollen and charcoal records from Gushantun peatland.We then used generalized linear modelling to investigate the impact of reconstructed changes in summer temperature,annual precipitation,background levels of fire,fire frequency and fire magnitude to identify the drivers of decadal-to-centennial changes in forest openness and composition.Changes in climate and fire regimes have independent impacts on the abundance of the key tree taxa.Climate variables are generally more important than fire variables in determining the abundance of individual taxa.Precipitation is the only determinant of forest openness,but summer temperature is more important than precipitation for individual tree taxa with warmer summers causing a decrease in cold-tolerant conifers and an increase in warmth-demanding broadleaved trees.Both background level and fire frequency have negative relationships with the abundance of most tree taxa;only Pinus increases as fire frequency increases.The magnitude of individual fires does not have a significant impact on species abundance on this timescale.Both climate and fire regime characteristics must be considered to understand changes in forest composition on the decadal-to-centennial timescale.There are differences,both in sign and magnitude,in the response of individual tree species to individual drivers.

A Statistical Approach for Predicting Grassland Degradation in Disturbance-Driven Landscapes

Maintaining a land base that supports safe and realistic training operations is a significant challenge for military land managers which can be informed by frequent monitoring of land condition in relation to management practices. This study explores the relationship between fire and trends in tallgrass prairie vegetation at military and non-military sites in the Kansas Flint Hills. The response variable was the long-term linear trend (2001-2010) of surface greenness measured by MODIS NDVI using BFAST time series trend analysis. Explanatory variables included fire regime (frequency and seasonality) and spatial strata based on existing management unit boundaries. Several non-spatial generalized linear models (GLM) were computed to explain trends by fire regime and/or stratification. Spatialized versions of the GLMs were also constructed. For non-spatial models at the military site, fire regime explained little (4%) of the observed surface greenness trend compared to strata alone (7% - 26%). The non-spatial and spatial models for the non-military site performed better for each explanatory variable and combination tested with fire regime. Existing stratifications contained much of the spatial structure in model residuals. Fire had only a marginal effect on surface greenness trends at the military site despite the use of burning as a grassland management tool. Interestingly, fire explained more of the trend at the non-military site and models including strata improved explanatory power. Analysis of spatial model predictors based on management unit stratification suggested ways to reduce the number of strata while achieving similar performance and may benefit managers of other public areas lacking sound data regarding land usage.

Smoke interacts with fire history to stimulate soil seed bank germination in Mediterranean woodlands

Aims Fire has important consequences on vegetation dynamics.In fire-prone areas,natural selection favors plant species,characterized by a large soil seed bank,and that their germination is stimu-lated by fire.Although seed germination stimulated by fire heat is common in the eastern Mediterranean Basin,only little is known about germination stimulation by smoke.We examined the inter-active effect of aerosol smoke and fire history on the germina-ble soil seed bank(GSSB)community in eastern Mediterranean woodlands.Methods We collected soil samples from sites that have been subjected to different fire frequencies during the last four decades and exposed them to aerosol smoke,with or without watering.By document-ing the seed germination patterns characterizing these samples,we could test for changes in the abundance and richness of the germi-nable seeds in the soil.Important Findings Total GSSB density was higher in sites that were burned more fre-quently during the last four decades.Exposure to aerosol smoke increased the GSSB density,and this pattern was more pronounced in samples originating from sites burned more frequently,as well as among annual species.Notably,exposing wet samples to aerosol smoke caused a significant reduction in GSSB density and richness.These results highlight the importance of exploring germination responses using intact soil samples,rather than synthetic seed com-munities.Moreover,our findings emphasize the important role smoke plays in shaping post-fire succession processes in the Mediterranean Basin,mainly by stimulating the germination of annual species.

Effects of fire history on animal communities:a systematic review

Fire is a natural agent with a paramount role in ecosystem functioning and biodiversity maintenance.Still,it can also act as a negative force against many ecosystems.Despite some knowledge of the interactions of fire and vegetation,there is no clear understanding of how different components of fire regimes(i.e.,severity,history,or frequency)influence known patterns of animal communities.Therefore,we performed a systematic review on the global responses of arthropods,birds,mammals,reptiles,and amphibians to different fire regimes.Specifically,we focused on assessing how fire severity,history,and frequency modulate the effect of fire on the richness and abundance of faunal communities.We conducted a systematic review of 566 papers retrieved from the Scopus database.We also scrutinized all the documents included in the meta‑analysis of Pastro et al.(Pastro et al.Glob Ecol Biogeogr 23:1146–1156,2014).Our selection criteria excluded studies without data on species richness or abundance.We also excluded studies without adequate controls and those without information about the fire regime of the study zone.After careful examination,we used data from 162 studies to perform a quantitative meta‑analysis.From the 162 studies meeting our selection criteria,nearly 60%of the studies are from North America,25%from Australia,11%from Europe,and 4%from the tropics.According to the ecological role of fire,90%of the studies were carried out in fire‑dependent ecosystems(i.e.,conifer forests,natural savannas,pastures).Finally,40%of the studies analyzed birds,22%mammals,and 20%arthropods.The meta‑analysis of the available evidence indicates that fire history is an important modulator of animal richness and abundance.Whether negative or positive,animal responses depended on the time since the last fire event.Considering that short‑term studies may not capture such a long‑term effect on fauna,this translates to more challenges at implementing fire management strategies.Whether or not we can anticipate the impact of the fire will then depend on future efforts to implement long‑term research.

Spatial distribution of charcoal in topsoil and its potential determinants on the Tibetan Plateau

As an important proxy for investigating past fire activities,charcoal is often used to explore the characteristics of fire distribution and its relationships with vegetation,climate,and human activities.Research into the spatial distribution and environmental determinants for charcoal,however,is still limited.In this study,we identified and counted charcoal from topsoil samples covering the Tibetan Plateau using the pollen methodology,and investigated its relationships with vegetation net primary production(NPP),elevation,climate(precipitation,mean temperature of the coldest month and warmest month)and human population by boosted regression trees(BRT).Results reveal that the concentration of microscopic charcoal,macroscopic charcoal,and total charcoal all increase from south-west to north-east,which is consistent with the trend that the population density on the Tibetan Plateau is high in the east and low in the west,suggesting that an increase in human activity is likely to promote the occurrence of fire.The BRT modeling reveals that NPP,elevation,and mean temperature of the coldest month are important factors for total charcoal concentration on the Tibetan Plateau,and the frequency and intensity of fires further increase with increasing vegetation biomass,decreasing elevation,and decreasing mean temperature of the coldest month.The spatial variation characteristics of charcoal from topsoil on the Tibetan Plateau not only reflect well the spatial fire situation in the region,but also have a good indicative significance for vegetation,climate,and human activities.