scholarly journals Spatio-temporal variation in dry season determines the Amazonian fire calendar

2021 ◽  
Author(s):  
Nathália S. Carvalho ◽  
Liana O. Anderson ◽  
Cássio Alencar Nunes ◽  
Ana Carolina Moreira Pessôa ◽  
Celso Henrique Leite Silva Junior ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Amazon Basin ◽  
Dry Season ◽  
Decision Makers ◽  
Fire Dynamics ◽  
Policies And Measures ◽  
Clear Link ◽  
Management Policies ◽  
Spatio Temporal

Abstract Fire is one of the main anthropogenic drivers that threatens the Amazon. Despite the clear link between rainfall and fire, the spatial and temporal relationship between these variables is still poorly understood in the Amazon. Here, we stratified the Amazon basin according to the dry season onset/end and investigated its relationship with the spatio-temporal variation of fire. We used monthly time series of active fires from 2003 to 2019 to characterize the fire dynamics throughout the year and to identify the fire peak months. More than 50% (32,246) of the annual mean active fires occurred in the peak month. In 52% of the cells, the peaks occurred between August-September and in 48% between October-March, showing well-defined seasonal patterns related to spatio-temporal variation of the dry season. Fire peaks occurred in the last two months of the dry season in 67% of the cells and in 20% in the first month of the rainy season. The shorter the dry season, the more concentrated was the occurrence of active fires in the peak month, with a predominance above 70% in cells with a dry season between one and three months. We defined a Critical Fire Period by identifying the consecutive months that concentrated at least 80% of active fires in the year. This period included two to three months between January-March in the northwest, and in the far north it lasted up to seven months, ending in March-April. In the south, it varied between two and three months, starting in August. In the northeast, it was three to four months, between August-December. By quantifying the role of the dry season in driving fire seasonality across the Amazon basin, we provide recommendations to monitor fire dynamics that can support decision makers in management policies and measures to avoid environmentally or socially harmful fires.

scholarly journals The role of socioeconomic and climatic factors in the spatio-temporal variation of human rabies in China

2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Danhuai Guo ◽  
Wenwu Yin ◽  
Hongjie Yu ◽  
Jean-Claude Thill ◽  
Weishi Yang ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Climatic Factors ◽  
Human Rabies ◽  
Spatio Temporal

scholarly journals Size, connectivity and edge effects of stream habitats explain spatio-temporal variation in brown trout ( Salmo trutta ) density

2021 ◽  
Vol 288 (1961) ◽  
Author(s):  
Carl Tamario ◽  
Erik Degerman ◽  
Daniela Polic ◽  
Petter Tibblin ◽  
Anders Forsman
Keyword(s):  
Temporal Variation ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Extinction Risk ◽  
Suitable Habitat ◽  
Habitat Patches ◽  
Lotic Habitats ◽  
Lotic Habitat ◽  
Spatio Temporal

Ecological theory postulates that the size and isolation of habitat patches impact the colonization/extinction dynamics that determine community species richness and population persistence. Given the key role of lotic habitats for life-history completion in rheophilic fish, evaluating how the distribution of swift-flowing habitats affects the abundance and dynamics of subpopulations is essential. Using extensive electrofishing data, we show that merging island biogeography with meta-population theory, where lotic habitats are considered as islands in a lentic matrix, can explain spatio-temporal variation in occurrence and density of brown trout ( Salmo trutta ). Subpopulations in larger and less isolated lotic habitat patches had higher average densities and smaller between-year density fluctuations. Larger lotic habitat patches also had a lower predicted risk of excessive zero-catches, indicative of lower extinction risk. Trout density further increased with distance from the edge of adjacent lentic habitats with predator ( Esox lucius ) presence, suggesting that edge- and matrix-related mortality contributes to the observed patterns. These results can inform the prioritization of sites for habitat restoration, dam removal and reintroduction by highlighting the role of suitable habitat size and connectivity in population abundance and stability for riverine fish populations.

scholarly journals Diversity of Pseudoscorpiones (Arthropoda: Arachnida) in two fragments of dry tropical forest in the colombian Caribbean region

Caldasia ◽  
2019 ◽  
Vol 41 (1) ◽  
pp. 139-151
Author(s):  
Eduardo Villarreal ◽  
Neis Martínez ◽  
Catalina Romero-Ortiz
Keyword(s):  
Tropical Forest ◽  
Temporal Variation ◽  
Rainy Season ◽  
Dry Season ◽  
Caribbean Region ◽  
Limited Information ◽  
Dry Tropical Forest ◽  
The Caribbean ◽  
Spatio Temporal ◽  
Collection Methods

The Dry Tropical Forest (DTF) is one of the most diverse yet threatened biomes of Colombia. There is limited information about the richness of the order Pseudoscorpiones (Arachnida) in this ecosystem in the country. Pseudoscorpions are ecologically interesting, as they may be good indicators of habitat conservation. However, it is still necessary to gather more knowledge related to its spatio-temporal variation. In this study, pseudoscorpion diversity variation was assessed in two fragments of the Dry Tropical Forest in the Caribbean region of Colombian: Reserva Campesina La Montaña (RCM) and Reserva La Flecha (RLF). Four samplings were carried out between March and September of 2016 to include the dry and rainy season. Pseudoscorpions were collected using litter sifting (SL) and manual capture (MC). A total of 260 individuals belonging to five families and eight species were collected. The most abundant was Pachyolpium granulatum (Olpiidae) and the richest family was Chernetidae. The collection methods were effective and complementary. Spatial variation was significant, but no temporal variation was observed however, there was a marked difference between the abundance at RCM in the dry season and the rainy season. In contrast, at RLF most individuals were found in the dry season in comparison with the rainy season. These new faunistic data is the first of its order in the Atlántico and Bolívar department.

scholarly journals Amazonian BC Contribution to the Vallunaraju Glacier Surface Melt

2020 ◽  
Author(s):  
Wilmer Sánchez ◽  
Carl Schmitt ◽  
Alexzander Santiago ◽  
Gerles Medina
Keyword(s):  
Black Carbon ◽  
Forest Fires ◽  
Radiative Forcing ◽  
Dry Season ◽  
Decision Makers ◽  
Ablation Zone ◽  
Wet Season ◽  
Glacier Surface ◽  
Glacial Retreat

The role of Black Carbon (BC) as a contributor to glacial retreat is of particular interest to the scientific community and decision makers, due to its impact on snow albedo and glacier melt. In this study, a thermal-optical instrument (LAHM) was used to measure effective Black Carbon (eBC) in a series of surface snow samples collected from the Vallunaraju glacier, Cordillera Blanca, between April 2019 and May 2020. The time series obtained indicates a marked seasonal variability of eBC with maximum concentrations during the dry season and dramatic decrease during the wet season. The concentrations detected ranged between a minimum of 3.73 ng/g and 4.23 ng/g during the wet season and a maximum of 214.13 ng/g and 181.60 ng/g during the dry season, in the accumulation and ablation zone. Using SNICAR model, the reduction of albedo was estimated at 6.36% and 6.60% during the dry season and 0.68% and 0.95% during the wet season, which represents an average radiative forcing of 4.52 ± 1.84 W/m2 and 4.69 ± 1.59 W/m2 in the accumulation zone, and 0.49 ± 0.27 W/m2 and 0.68 ± 0.43 W/m2 in the ablation zone. The melting of snow due to the eBC translates into 80.18 ± 37.30 kg/m2 and 83.16 ± 32.75 kg/m2 during the dry season, and 7.91 ± 4.29 kg/m2 and 10.85 ± 6.62 kg/m2 during the wet season, in the accumulation and ablation zones, respectively. Finally, the HYSPLIT trajectory assessment shows that aerosols predominate in the Amazon rainforest, especially when forest fires are most abundant according to VIIRS images.

scholarly journals Tree-ring oxygen isotopes record a decrease in Amazon dry season rainfall over the past 40 years

2021 ◽  
Author(s):  
Bruno B. L. Cintra ◽  
Manuel Gloor ◽  
Arnoud Boom ◽  
Jochen Schöngart ◽  
Jessica C. A. Baker ◽  
...  
Keyword(s):  
Amazon Basin ◽  
North Atlantic Ocean ◽  
Dry Season ◽  
The Past ◽  
Oxygen Isotope Ratios ◽  
Tropical North Atlantic ◽  
Underlying Causes ◽  
Drying Trend

AbstractExtant climate observations suggest the dry season over large parts of the Amazon Basin has become longer and drier over recent decades. However, such possible intensification of the Amazon dry season and its underlying causes are still a matter of debate. Here we used oxygen isotope ratios in tree rings (δ18OTR) from six floodplain trees from the western Amazon to assess changes in past climate. Our analysis shows that δ18OTR of these trees is negatively related to inter-annual variability of precipitation during the dry season over large parts of the Amazon Basin, consistent with a Rayleigh rainout model. Furthermore δ18OTR increases by approximately 2‰ over the last four decades (~ 1970–2014) providing evidence of an Amazon drying trend independent from satellite and in situ rainfall observations. Using a Rayleigh rainout framework, we estimate basin-wide dry season rainfall to have decreased by up to 30%. The δ18OTR record further suggests such drying trend may not be unprecedented over the past 80 years. Analysis of δ18OTR with sea surface temperatures indicates a strong role of a warming Tropical North Atlantic Ocean in driving this long-term increase in δ18OTR and decrease in dry season rainfall.

scholarly journals Amazon Basin climate under global warming: the role of the sea surface temperature

2008 ◽  
Vol 363 (1498) ◽  
pp. 1753-1759 ◽  
Author(s):  
Phil P Harris ◽  
Chris Huntingford ◽  
Peter M Cox
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Amazon Basin ◽  
Dry Season ◽  
Combined Effect ◽  
Sea Surface ◽  
Carbon Cycle Model

The Hadley Centre coupled climate–carbon cycle model (HadCM3LC) predicts loss of the Amazon rainforest in response to future anthropogenic greenhouse gas emissions. In this study, the atmospheric component of HadCM3LC is used to assess the role of simulated changes in mid-twenty-first century sea surface temperature (SST) in Amazon Basin climate change. When the full HadCM3LC SST anomalies (SSTAs) are used, the atmosphere model reproduces the Amazon Basin climate change exhibited by HadCM3LC, including much of the reduction in Amazon Basin rainfall. This rainfall change is shown to be the combined effect of SSTAs in both the tropical Atlantic and the Pacific, with roughly equal contributions from each basin. The greatest rainfall reduction occurs from May to October, outside of the mature South American monsoon (SAM) season. This dry season response is the combined effect of a more rapid warming of the tropical North Atlantic relative to the south, and warm SSTAs in the tropical east Pacific. Conversely, a weak enhancement of mature SAM season rainfall in response to Atlantic SST change is suppressed by the atmospheric response to Pacific SST. This net wet season response is sufficient to prevent dry season soil moisture deficits from being recharged through the SAM season, leading to a perennial soil moisture reduction and an associated 30% reduction in annual Amazon Basin net primary productivity (NPP). A further 23% NPP reduction occurs in response to a 3.5°C warmer air temperature associated with a global mean SST warming.

Interpreting satellite column observations of formaldehyde over tropical South America

2007 ◽  
Vol 365 (1856) ◽  
pp. 1741-1751 ◽  
Author(s):  
Paul I Palmer ◽  
Michael P Barkley ◽  
Thomas P Kurosu ◽  
Alastair C Lewis ◽  
Julie E Saxton ◽  
...  
Keyword(s):  
South America ◽  
Amazon Basin ◽  
Regional Scale ◽  
Quantitative Information ◽  
Dry Season ◽  
High Yield ◽  
Annual Cycles ◽  
Tropical South America

Space-borne column measurements of formaldehyde (HCHO), a high-yield oxidation product of volatile organic compounds (VOCs), represent important constraints for quantifying net regional fluxes of VOCs. Here, we interpret observed distributions of HCHO columns from the Global Ozone Monitoring Experiment (GOME) over tropical South America during 1997–2001. We present the first comparison of year-long in situ isoprene concentrations and fire-free GOME HCHO columns over a tropical ecosystem. GOME HCHO columns and in situ isoprene concentrations are elevated in the wet and dry seasons, with the highest values in the dry season. Previous analysis of the in situ data highlighted the possible role of drought in determining the elevated concentrations during the dry season, inferring the potential of HCHO columns to provide regional-scale constraints for estimating the role of drought on isoprene emissions. The agreement between the observed annual cycles of GOME HCHO columns and Along-Track Scanning Radiometer firecount data over the Amazon basin (correlations typically greater than 0.75 for a particular year) illustrates the potential of HCHO column to provide quantitative information about biomass burning emissions.

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