Spatial patterns of fire patch size and shape complexity in the Brazilian savanna

2021 ◽  
Author(s):  
Joana Nogueira ◽  
Julia Rodrigues ◽  
Jan Lehmann ◽  
Hanna Meyer ◽  
Renata Libonati
Keyword(s):  
Land Use ◽  
Shape Index ◽  
Fire Spread ◽  
Core Area ◽  
Validation Dataset ◽  
Burned Area ◽  
Fire Size ◽  
Size And Shape ◽  
The North ◽  
Shape Complexity

<p>Fire events on a landscape scale are a widespread global phenomenon that influences the interactions between atmosphere and biosphere. Global burned area (BA) products derived from satellite images are used in dynamic vegetation fire modules to estimate greenhouse gas emissions, available fuel biomass and anthropic factors driving fire spread. Fire size and shape complexity from individual fire events can provide better estimates of fuel consumption, fire intensity, post fire vegetation recovery and their effects on landscape changes to better understand regional fire dynamics. Especially in the Brazilian savannas (Cerrado), a mosaic of heterogeneous vegetation where has prevailed an official “zero-fire” policy for decades leading to an increase in large wildfires, intensified also by rapid changes of land use using fire to land clearing in agriculture and livestock purposes. In this way, we aim to assess the fire size and shape patterns in Cerrado from 2013 to 2015, identifying each fire patch event from Landsat BA product and calculating its fire features with landscape metrics. We calculated its surface area to evaluate fire size and the metrics of shape index, core area and eccentricity from an ellipse fitting from burned pixels to estimate the fire shape complexity. The study focused on 48 Landsat path/row scenes and the analysis final compared the fire features of overlapped patches between the years. The total number of coincident fire patches is higher between the years 2013 and 2015 than 2013-2014 and 2014-2015. Large fires are found in the north and east regions for all comparisons. In this region, high core area values are consistent for having large areas of burnt patches and low shape index values and more elongated patches revealed a low fire shape complexity. These results demonstrate a greater burned area in the north, where the remaining native vegetation and less fragmented landscapes allow the fire to spread, when associated with favorable meteorological conditions. However, with the implementation of a new agricultural frontier in 2015, this region is under greater anthropic pressure with positive trends to land use. In the south, the fire shapes are already more complex and smaller because they are from agricultural areas historically developed, and consequently the landscape is more fragmented. Our results demonstrate a distinct spatial pattern of fire shape and size in Cerrado related to fragmentation of landscape and fire use to land cleaning. This information can help the modelling estimates of fire spread processes driven by topography, orientation of watersheds or dominant winds at local level, contributing to understanding the feedback with land cover/use, climate and biophysical characteristics at regional level to develop strategies for fire management.</p><p><strong>Acknowledges:</strong> J.N is funded by the 'Women in Research'-fellowship program (WWU Münster) and within the context of BIOBRAS Project “Research-based learning in neglected biodiverse ecosystems of Brazil”; funding by DAAD (number 57393735); validation dataset was performed under the Andurá project (number 441971/2018–0) funding by CNPq</p>

Distribution of residual vegetation associated with large fires in Alberta

1987 ◽  
Vol 17 (10) ◽  
pp. 1207-1212 ◽  
Author(s):  
Kevin E. Eberhart ◽  
Paul M. Woodard
Keyword(s):  
Shape Index ◽  
Size Class ◽  
Burned Area ◽  
Fire Size ◽  
Size Classes ◽  
Size And Shape ◽  
The Third ◽  
Island Area ◽  
Large Fires

Fire size and shape, number and size of islands of residual vegetation, amount of edge, and distances to residual vegetation were analyzed for 69 fires that burned in Alberta between 1970 and 1983. These fires ranged in size from 21 to 17 770 ha. Distribution of residual vegetation was compared among five fire size classes. Fires in the smallest size class (20–40 ha) did not contain any islands of unburned vegetation. Percent of area within the fire perimeter that was actually disturbed decreased with increasing fire size. The number of unburned islands per 100 ha was highest for the third and fourth largest fire size classes (201–400 and 401–2000 ha). Median island area per fire, fire shape index, and edge index increased with fire size. Percentages of burned area within 100, 200, 300, 400, and 500 m of residual vegetation decreased with increasing fire size. These results indicate decreased potential for natural reforestation and increased benefits to some wildlife habitats as fire size increases.

scholarly journals Varying relationships between fire intensity and fire size at global scale

2018 ◽  
Author(s):  
Pierre Laurent ◽  
Florent Mouillot ◽  
Maria Vanesa Moreno ◽  
Chao Yue ◽  
Philippe Ciais
Keyword(s):  
Patch Size ◽  
Empirical Relation ◽  
Satellite Observation ◽  
Fire Spread ◽  
Global Scale ◽  
Fire Season ◽  
Fire Intensity ◽  
Burned Area ◽  
Fire Size ◽  
Fire Emissions

Abstract. Vegetation fires are an important process in the Earth system. Fire intensity locally impacts fuel consumption, damage to the vegetation, chemical composition of fire emissions but also how fires spread across landscapes. It has been observed that fire occurrence, defined as the frequency of active fires detected by the MODIS sensor, is related to intensity with a hump-shaped empirical relation meaning that occurrence reaches a maximum at intermediate intensity. Raw burned area products obtained from remote-sensing can not discriminate between ignition and propagation processes. Here we use the newly delivered global FRY database, which provides fire patch functional traits including fire patch size from satellite observation, to go beyond burned area, and to test if fire size is driven by fire intensity at global scale as expected from empirical fire spread models. We show that in most regions of the world the linear relationship between fire intensity and fire patch size saturates for a threshold of intermediate intensity fires. The value of the threshold differs from one region to another, and we suggest that it might be driven by drought, and the amount of available biomass. In some regions, once this threshold is reached, we also observe that fire size decreases for the most intense fires, which mostly happen in the late fire season. According to the percolation theory, we suggest that this effect is a consequence of the increasing fragmentation of fuel continuity along the fire season so that landscape-scale feedbacks should be developed in global fire modules.

scholarly journals Understanding the Impact of Different Landscape-Level Fuel Management Strategies on Wildfire Hazard in Central Portugal

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 522
Author(s):  
Akli Benali ◽  
Ana C. L. Sá ◽  
João Pinho ◽  
Paulo M. Fernandes ◽  
José M. C. Pereira
Keyword(s):  
Management Strategies ◽  
Treatment Strategies ◽  
Fire Season ◽  
Burned Area ◽  
Treatment Area ◽  
Fuel Treatment ◽  
The North ◽  
Wildfire Hazard ◽  
Central Portugal ◽  
The Impact

The extreme 2017 fire season in Portugal led to widespread recognition of the need for a paradigm shift in forest and wildfire management. We focused our study on Alvares, a parish in central Portugal located in a fire-prone area, which had 60% of its area burned in 2017. We evaluated how different fuel treatment strategies may reduce wildfire hazard in Alvares through (i) a fuel break network with different extents corresponding to different levels of priority and (ii) random fuel treatments resulting from a potential increase in stand-level management intensity. To assess this, we developed a stochastic wildfire simulation system (FUNC-SIM) that integrates uncertainties in fuel distribution over the landscape. If the landscape remains unchanged, Alvares will have large burn probabilities in the north, northeast and center-east areas of the parish that are very often associated with high fireline intensities. The different fuel treatment scenarios decreased burned area between 12.1–31.2%, resulting from 1–4.6% increases in the annual treatment area and reduced the likelihood of wildfires larger than 5000 ha by 10–40%. On average, simulated burned area decreased 0.22% per each ha treated, and cost-effectiveness decreased with increasing area treated. Overall, both fuel treatment strategies effectively reduced wildfire hazard and should be part of a larger, holistic and integrated plan to reduce the vulnerability of the Alvares parish to wildfires.

scholarly journals Agriculture and land use in the North of Russia: Case study of Karelia and Yakutia

2020 ◽  
Vol 12 (1) ◽  
pp. 1497-1511
Author(s):  
Alexey Naumov ◽  
Varvara Akimova ◽  
Daria Sidorova ◽  
Mikhail Topnikov
Keyword(s):  
Land Use ◽  
Agricultural Development ◽  
Agricultural Land ◽  
Geographical Location ◽  
Special Role ◽  
Sources Of Information ◽  
Local Conditions ◽  
Climate Conditions ◽  
The North ◽  
The Republic

AbstractDespite harsh climate, agriculture on the northern margins of Russia still remains the backbone of food security. Historically, in both regions studied in this article – the Republic of Karelia and the Republic of Sakha (Yakutia) – agricultural activities as dairy farming and even cropping were well adapted to local conditions including traditional activities such as horse breeding typical for Yakutia. Using three different sources of information – official statistics, expert interviews, and field observations – allowed us to draw a conclusion that there are both similarities and differences in agricultural development and land use of these two studied regions. The differences arise from agro-climate conditions, settlement history, specialization, and spatial pattern of economy. In both regions, farming is concentrated within the areas with most suitable natural conditions. Yet, even there, agricultural land use is shrinking, especially in Karelia. Both regions are prone to being affected by seasonality, but vary in the degree of its influence. Geographical location plays special role, and weaknesses caused by remoteness to some extent become advantage as in Yakutia. Proximity effect is controversial. In Karelia, impact of neighboring Finland is insignificant compared with the nearby second Russian city – Saint Petersburg.

scholarly journals Response of simulated burned area to historical changes in environmental and anthropogenic factors: a comparison of seven fire models

2019 ◽  
Vol 16 (19) ◽  
pp. 3883-3910 ◽  
Author(s):  
Lina Teckentrup ◽  
Sandy P. Harrison ◽  
Stijn Hantson ◽  
Angelika Heil ◽  
Joe R. Melton ◽  
...  
Keyword(s):  
Land Use ◽  
Co2 Concentration ◽  
Fire Regimes ◽  
Atmospheric Co2 ◽  
Anthropogenic Factors ◽  
Burned Area ◽  
Earth System ◽  
Atmospheric Co2 Concentration ◽  
Fire Models ◽  
The Impact

Abstract. Understanding how fire regimes change over time is of major importance for understanding their future impact on the Earth system, including society. Large differences in simulated burned area between fire models show that there is substantial uncertainty associated with modelling global change impacts on fire regimes. We draw here on sensitivity simulations made by seven global dynamic vegetation models participating in the Fire Model Intercomparison Project (FireMIP) to understand how differences in models translate into differences in fire regime projections. The sensitivity experiments isolate the impact of the individual drivers on simulated burned area, which are prescribed in the simulations. Specifically these drivers are atmospheric CO2 concentration, population density, land-use change, lightning and climate. The seven models capture spatial patterns in burned area. However, they show considerable differences in the burned area trends since 1921. We analyse the trajectories of differences between the sensitivity and reference simulation to improve our understanding of what drives the global trends in burned area. Where it is possible, we link the inter-model differences to model assumptions. Overall, these analyses reveal that the largest uncertainties in simulating global historical burned area are related to the representation of anthropogenic ignitions and suppression and effects of land use on vegetation and fire. In line with previous studies this highlights the need to improve our understanding and model representation of the relationship between human activities and fire to improve our abilities to model fire within Earth system model applications. Only two models show a strong response to atmospheric CO2 concentration. The effects of changes in atmospheric CO2 concentration on fire are complex and quantitative information of how fuel loads and how flammability changes due to this factor is missing. The response to lightning on global scale is low. The response of burned area to climate is spatially heterogeneous and has a strong inter-annual variation. Climate is therefore likely more important than the other factors for short-term variations and extremes in burned area. This study provides a basis to understand the uncertainties in global fire modelling. Both improvements in process understanding and observational constraints reduce uncertainties in modelling burned area trends.

scholarly journals Winter pasture and cover crops and their effects on soil and summer grain crops

2011 ◽  
Vol 46 (10) ◽  
pp. 1357-1363 ◽  
Author(s):  
Alvadi Antonio Balbinot Junior ◽  
Milton da Veiga ◽  
Anibal de Moraes ◽  
Adelino Pelissari ◽  
Álvaro Luiz Mafra ◽  
...  
Keyword(s):  
Land Use ◽  
Common Bean ◽  
Cover Crops ◽  
Nitrogen Fertilization ◽  
Soil Compaction ◽  
Surface Soil ◽  
Soil Layer ◽  
N Fertilization ◽  
The North ◽  
Oilseed Radish

The objective of this work was to evaluate the effect of winter land use on the amount of residual straw, the physical soil properties and grain yields of maize, common bean and soybean summer crops cultivated in succession. The experiment was carried out in the North Plateau of Santa Catarina state, Brazil, from May 2006 to April 2010. Five strategies of land use in winter were evaluated: intercropping with black oat + ryegrass + vetch, without grazing and nitrogen (N) fertilization (intercropping cover); the same intercropping, with grazing and 100 kg ha-1 of N per year topdressing (pasture with N); the same intercropping, with grazing and without nitrogen fertilization (pasture without N); oilseed radish, without grazing and nitrogen fertilization (oilseed radish); and natural vegetation, without grazing and nitrogen fertilization (fallow). Intercropping cover produces a greater amount of biomass in the system and, consequently, a greater accumulation of total and particulate organic carbon on the surface soil layer. However, land use in winter does not significantly affect soil physical properties related to soil compaction, nor the grain yield of maize, soybean and common bean cultivated in succession.

scholarly journals THE MERCURIO GUNFLINTS: A TECHNO-TYPOLOGICAL AND CULTURAL ASSESSMENT

2016 ◽  
Vol 96 ◽  
pp. 363-389 ◽  
Author(s):  
Paolo Biagi ◽  
Elisabetta Starnini ◽  
Carlo Beltrame
Keyword(s):  
Nineteenth Century ◽  
Northern Italy ◽  
Size And Shape ◽  
Manufacturing Technique ◽  
The North ◽  
Major Significance ◽  
Cultural Assessment ◽  
The Mediterranean ◽  
Napoleonic Era ◽  
Small Finds

The discovery of the wreck of the brig Mercurio, which sank in 1812 in the waters of the north Adriatic, is of major significance for the study of Italic Kingdom vessels from the Napoleonic era. The underwater excavations carried out in 2004–11 led to the recovery of many small finds, among which are several gunflints of different size and shape. The Mercurio gunflints were produced mainly from blades using a technique in use in Britain and France, but also in the workshops of the Lessini Hills around Ceredo (Verona province, northern Italy). We suggest that the flint employed for their manufacture probably came from Monte Baldo, in the Trentino, or perhaps from the River Tagliamento, in Friuli. We can exclude the possibility that the specimens recovered from the shipwreck were made from French flint because of the typically north Italian manufacturing technique and the character of the grey Treveti-derived flint. Given the complexity of the period during which the Grado (or Pirano) battle took place, the study of even such small items can contribute to a better interpretation of the dramatic events that characterised the beginning of the nineteenth century in that part of the Mediterranean.

Field Margin Weed-Species Diversity in Relation to Landscape Attributes and Adjacent Land Use

Weed Science ◽  
2007 ◽  
Vol 55 (2) ◽  
pp. 129-136 ◽  
Author(s):  
Lynn M. Sosnoskie ◽  
Edward C. Luschei ◽  
Mark A. Fanning
Keyword(s):  
Land Use ◽  
Species Richness ◽  
Agricultural Landscape ◽  
Elevation Gradient ◽  
Shape Index ◽  
Diversity Indices ◽  
Weed Species ◽  
Field Margin ◽  
Local Climate ◽  
Modeling Strategy

The importance of managing weeds in seminatural habitats that are adjacent to farm fields is unclear. Weedy-margin vegetation may harbor pests or pathogens and may ALSo serve as source populations for ongoing immigration of weeds into the field. It is ALSo possible, however, that margin vegetation provides habitat for organisms that consume weed seeds or suppress the likelihood of pest or pathogen outbreak. We examined the nature of margin habitat using spatial-scaling of Weed-Species richness as an ecological assay. In 2003, we recorded the occurrence of weedy species along the perimeters of 63 fields in Wisconsin. The fields were distributed within six counties that differed in topography, geological history, local climate, and soil type and which spanned the range of variability in the agricultural landscape. We identified seven habitats that differed in geology and land use. The relationship between species richness and margin class was estimated using an analog of the power law. Additionally, we investigated broadscale correlates of habitat heterogeneity at the field level, using a modeling strategy that included additional explanatory factors logically connected to plant diversity. Using a model-confrontation approach, the survey supported the inclusion of two topographical diversity indices, elevation gradient and a field-shape index, into our model. Our broadscale survey provides information on one of a suite of important considerations needed to make decisions about the importance of managing weeds in field margins.

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