scholarly journals Anthropogenic Fires in West African Landscapes: A Spatially Explicit Model Perspective of Humanized Savannas

Fire ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 62
Author(s):  
Sébastien Caillault ◽  
Paul Laris ◽  
Cyril Fleurant ◽  
Daniel Delahaye ◽  
Aziz Ballouche

Fire regimes are important components of environmental dynamics, but our understanding of them is limited. Despite recent advances in the methodologies used to remotely sense and map fires and burned areas and new case studies that shed light on local fire use and management practices, the scientific community still has much to learn about anthropogenic fire regimes. We identify two areas for improvement: first, the fine-scale heterogeneity of fire dynamics for specific regions is often masked by global-scale approaches, and second, barriers between the disciplines focusing on fire impacts hamper the development of knowledge of the human dimensions of fire regimes. To address the “blind spot” that these limitations create, we present a simple dynamic model of fire ignition in savanna systems. The aim is to connect the local and global scales of fire regimes by focusing on human fire management (anthropogenic fire). Our dynamical model is based on a study area in Western Burkina Faso and integrates biophysical elements (climate and soil data), land cover, and fire management scenarios based on field surveys. The simulation results offer contrasting views of the impact of local fire management practices on regional fire regimes observed in savannas. Fire density and frequency are local variables that clearly change the fire regimes despite a complex and constrained biophysical system. This experience, drawing from fieldwork and modelling, may be a way to integrate some key aspects of anthropogenic fire research in savanna systems.

2021 ◽  
Author(s):  
Sara Minoli ◽  
Jonas Jägermeyr ◽  
Senthold Asseng ◽  
Christoph Müller

<p>Broad evidence is pointing at possible adverse impacts of climate change on crop yields. Due to scarce information about farming management practices, most global-scale studies, however, do not consider adaptation strategies.</p><p>Here we integrate models of farmers' decision making with crop biophysical modeling at the global scale to investigate how accounting for adaptation of crop phenology affects projections of future crop productivity under climate change. Farmers in each simulation unit are assumed to adapt crop growing periods by continuously selecting sowing dates and cultivars that match climatic conditions best. We compare counterfactual management scenarios, assuming crop calendars and cultivars to be either the same as in the reference climate – as often assumed in previous climate impact assessments – or adapted to future climate.</p><p>Based on crop model simulations, we find that the implementation of adapted growing periods can substantially increase (+15%) total crop production in 2080-2099 (RCP6.0). In general, summer crops are responsive to both sowing and harvest date adjustments, which result in overall longer growing periods and improved yields, compared to production systems without adaptation of growing periods. Winter wheat presents challenges in adapting to a warming climate and requires region-specific adjustments to pre and post winter conditions. We present a systematic evaluation of how local and climate-scenario specific adaptation strategies can enhance global crop productivity on current cropland. Our findings highlight the importance of further research on the readiness of required crop varieties.</p>


2016 ◽  
Vol 154 (7) ◽  
pp. 1153-1170 ◽  
Author(s):  
E. EBRAHIMI ◽  
A. M. MANSCHADI ◽  
R. W. NEUGSCHWANDTNER ◽  
J EITZINGER ◽  
S. THALER ◽  
...  

SUMMARYClimate change is expected to affect optimum agricultural management practices for autumn-sown wheat, especially those related to sowing date and nitrogen (N) fertilization. To assess the direction and quantity of these changes for an important production region in eastern Austria, the agricultural production systems simulator was parameterized, evaluated and subsequently used to predict yield production and grain protein content under current and future conditions. Besides a baseline climate (BL, 1981–2010), climate change scenarios for the period 2035–65 were derived from three Global Circulation Models (GCMs), namely CGMR, IPCM4 and MPEH5, with two emission scenarios, A1B and B1. Crop management scenarios included a combination of three sowing dates (20 September, 20 October, 20 November) with four N fertilizer application rates (60, 120, 160, 200 kg/ha). Each management scenario was run for 100 years of stochastically generated daily weather data. The model satisfactorily simulated productivity as well as water and N use of autumn- and spring-sown wheat crops grown under different N supply levels in the 2010/11 and 2011/12 experimental seasons. Simulated wheat yields under climate change scenarios varied substantially among the three GCMs. While wheat yields for the CGMR model increased slightly above the BL scenario, under IPCM4 projections they were reduced by 29 and 32% with low or high emissions, respectively. Wheat protein appears to increase with highest increments in the climate scenarios causing the largest reductions in grain yield (IPCM4 and MPEH-A1B). Under future climatic conditions, maximum wheat yields were predicted for early sowing (September 20) with 160 kg N/ha applied at earlier dates than the current practice.


2008 ◽  
Vol 8 (7) ◽  
pp. 1911-1924 ◽  
Author(s):  
Y. Le Page ◽  
J. M. C. Pereira ◽  
R. Trigo ◽  
C. da Camara ◽  
D. Oom ◽  
...  

Abstract. Vegetation fires have been acknowledged as an environmental process of global scale, which affects the chemical composition of the troposphere, and has profound ecological and climatic impacts. However, considerable uncertainty remains, especially concerning intra and inter-annual variability of fire incidence. The main goals of our global-scale study were to characterise spatial-temporal patterns of fire activity, to identify broad geographical areas with similar vegetation fire dynamics, and to analyse the relationship between fire activity and the El Niño-Southern Oscillation. This study relies on 10 years (mid 1996–mid 2006) of screened European Space Agency World Fire Atlas (WFA) data, obtained from Along Track Scanning Radiometer (ATSR) and Advanced ATSR (AATSR) imagery. Empirical Orthogonal Function analysis was used to reduce the dimensionality of the dataset. Regions of homogeneous fire dynamics were identified with cluster analysis, and interpreted based on their eco-climatic characteristics. The impact of 1997–1998 El Niño is clearly dominant over the study period, causing increased fire activity in a variety of regions and ecosystems, with variable timing. Overall, this study provides the first global decadal assessment of spatial-temporal fire variability and confirms the usefulness of the screened WFA for global fire ecoclimatology research.


2013 ◽  
Vol 22 (3) ◽  
pp. 394 ◽  
Author(s):  
Grant L. Harley ◽  
Henri D. Grissino-Mayer ◽  
Sally P. Horn

We focussed on the influence of historical fire and varied fire management practices on the structure of globally endangered pine rockland ecosystems on two adjacent islands in the Florida Keys: Big Pine Key and No Name Key. We reconstructed fire history in two stands from fire scars on South Florida slash pines (Pinus elliottii Engelm. var. densa Little & Dor.) that were accurately dated using dendrochronology, and quantified stand structure to infer successional trajectories. Fire regimes on Big Pine Key and No Name Key over the past 150 years differed in fire return interval and spatial extent. Fire scar analysis indicated that fires burnt at intervals of 6 and 9 years (Weibull median probability interval) on Big Pine Key and No Name Key with the majority of fires occurring late in the growing season. On Big Pine Key, pine recruitment was widespread, likely due to multiple, widespread prescribed burns conducted since 2000. No Name Key experienced fewer fires than Big Pine Key, but pines recruited at the site from at least the 1890s through the 1970s. Today, pine recruitment is nearly absent on No Name Key, where fire management practices since 1957 could result in loss of pine rockland habitat.


1997 ◽  
Vol 36 (5) ◽  
pp. 381-387 ◽  
Author(s):  
Alain Mailhot ◽  
Alain N. Rousseau ◽  
Serge Massicotte ◽  
Jacques Dupont ◽  
Jean-Pierre Villeneuve

This paper presents a general description and the state of progress of the GIBSI system, a watershed-based software system for integrated management of surface water quality. This spatial support-decision system is designed to assist decision makers as well as water resources professionals. An integrated structure composed of mathematical models, a Geographical Information System (GIS) and a DataBase Management System (DBMS) characterizes the system. This means interactions between users and system components are made through a single user-friendly interface. A simple scenario approach is used to examine the impact of alternative urban, industrial, and agricultural management practices on surface water quality. Interpretation of results is based on comparing different management scenarios with a reference state or other previously defined scenarios.


Author(s):  
Paola Sabbion

Water quality, flooding risk, and water consumption in urban areas are emerging  issues. Urban impervious surfaces increase stormwater runoff,  affecting ecosystems  and leading to hydrogeological instability and flooding risk. Sustainable urban design strategies can contribute to counteract the negative impact of anthropic activities both at city-scale and global scale. Green and Blue Infrastructure (GBI) approaches, in particular, are an alternative to stormwater traditional management. In Europe, Sustainable Drainage System implementation copes with impervious surfaces to achieve water quality, amenity, and biodiversity increase. Best Management Practices, developed mainly in the USA, focus on specific measures for sustainable stormwater treatment. Water Sensitive Urban Design, spread in Australia and England, also aims to minimize the impact of developed areas preventing flood risk, limiting water consumption and enhancing environmental quality. In the USA and Canada, Low Impact Development offers design strategies to manage runoff and deliver structural practices to mimic predevelopment processes of infiltration, filtration and detention.


2021 ◽  
Author(s):  
Mariano Crimaldi ◽  
Giuseppe Francesco Cesare Lama

<p>The aim of this study is the assessment of the effect of riparian vegetation management practices on the hydrodynamic behaviour of vegetated water bodies colonized by riparian weed species. The present study was carried out by calibrating the most suitable literature models on flow resistance of vegetated flows, by considering different riparian vegetation management scenarios. The key dimensional features of the examined riparian vegetation elements were estimated by comparing the outcomes of the digital processing of remote sensing and proximity sensors extremely widespread in both agricultural and forestry studies and applications. The main remarks of this study well demonstrated that the knowledge of the hydraulic and hydrological proprieties of vegetated flows at field scale is sensibly affected by the uncertainties in the measurements of riparian vegetation biomass and water quality, differently from experimental analyses conducted in dedicated flumes in the laboratory performed in standard environment conditions.</p>


2007 ◽  
Vol 7 (6) ◽  
pp. 17299-17338 ◽  
Author(s):  
Y. Le Page ◽  
J. M. C. Pereira ◽  
R. Trigo ◽  
C. da Camara ◽  
D. Oom ◽  
...  

Abstract. Vegetation fires have been acknowledged as an environmental process of global scale, which affects the chemical composition of the troposphere, and has profound ecological and climatic impacts. However, considerable uncertainty remains, especially concerning intra and inter-annual variability of fire incidence. The main goals of our global-scale study were to characterise spatial-temporal patterns of fire activity, to identify broad geographical areas with similar vegetation fire dynamics, and to analyse the relationship between fire activity and the El Niño-Southern Oscillation. This study relies on 10 years (mid 1996–mid 2006) of screened European Space Agency World Fire Atlas (WFA) data, obtained from Along Track Scanning Radiometer (ATSR) and Advanced ATSR (AATSR) imagery. Empirical Orthogonal Function analysis was used to reduce the dimensionality of the dataset. Regions of homogeneous fire dynamics were identified with cluster analysis, and interpreted based on their eco-climatic characteristics. The impact of 1997–1998 El Niño is clearly dominant over the study period, causing increased fire activity in a variety of regions and ecosystems, with variable timing. Overall, this study provides the first global decadal assessment of spatio-temporal fire variability and confirms the usefulness of the screened WFA for global fire ecoclimatology research.


2020 ◽  
Author(s):  
Yang Su ◽  
Benoît Gabrielle ◽  
David Makowski

Abstract Conservation agriculture (CA) is being promoted as a set of management practices that can sustain crop production while providing positive environmental externalities. However, its impact on crop productivity is still hotly debated, and how this productivity will be affected by climate change remains uncertain. Here we compared the productivity of CA vs. conventional tillage (CT) systems under current and future climate conditions using a probabilistic machine-learning approach at the global scale. We reveal large differences in the probability of yield gains with CA across crop types, climate zones, and geographical regions. We show that, for most crops, CA performed better in continental, arid and temperate regions than in tropical ones. Under future climate conditions, the relative productive performance of CA is expected to increase for maize in almost all cropping areas within the tropical band, thus improving the competitiveness of CA for this major crop.


1994 ◽  
Vol 70 (2) ◽  
pp. 164-173 ◽  
Author(s):  
David L. Martell

Results are presented for an assessment of the impact of fire on timber supply in the province of Ontario. Historical fire report data are used to develop statistical summaries of fire regimes in terms of annual fire occurrence and area burned by administrative district and region. A simple hypothetical jack pine forest is used to illustrate how forest level timber harvest scheduling models can be employed to assess the timber supply implications of fire management regimes. Although fire may have had a significant detrimental impact on timber supply in some parts of the Northwestern region during the 1976-88 period, the effectiveness of Ontario's forest fire management system is such that timber supply in most districts has not been significantly diminished by fire. The results of our timber supply analysis, and the fact that fire management also benefits public safety and reduces property loss, suggest forest fire management is profitable in Ontario. Key words: forest fire impact, timber supply, mathematical programming, Ontario


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