Characterising weather patterns associated with fire in a seasonally dry tropical forest in southern India

2014 ◽  
Vol 23 (2) ◽  
pp. 196 ◽  
Author(s):  
Nandita Mondal ◽  
Raman Sukumar

Anthropogenic fires in seasonally dry tropical forests are a regular occurrence during the dry season. Forest managers in India, who presently follow a fire suppression policy in such forests, would benefit from a system of assessing the potential risk to fire on a particular day. We examined the relationship between weather variables (seasonal rainfall, relative humidity, temperature) and days of fire during the dry seasons of 2004–2010, based on MODIS fire incident data in the seasonally dry tropical forests of Mudumalai in the Western Ghats, southern India. Logistic regression analysis showed that high probabilities of a fire day, indicating successful ignition of litter and grass fuel on the forest floor, were associated with low levels of early dry season rainfall, low daily average relative humidity and high daily average temperatures. These weather conditions are representative of low moisture levels of fine fuels, suggesting that the occurrence of fire is moderated by environmental conditions that reduce the flammability of fine fuels in the dry tropics. We propose a quantitative framework for assessing risk of a fire day to assist forest managers in anticipating fire occurrences in this seasonally dry tropical forest, and possibly for those across South Asia.

2020 ◽  
Vol 98 (4) ◽  
pp. 441-467
Author(s):  
Consuelo Medina-García ◽  
Alejandro Velázquez ◽  
Joaquin Giménez de Azcárate ◽  
Miguel Ángel Macías-Rodríguez ◽  
Alejandra Larrazábal ◽  
...  

Background: seasonally dry tropical forests are considered critical and important ecosystems because they harbor exceptional biological diversity. Mexico lacks sound phytosociological studies of Seasonally Dry Tropical Forest and Michoacán is no exception. The present study may be regarded the first phytosociological in most of the Mexican pacific coast where seasonally dry tropical forests occurs. Questions/Objective: We aimed at describing the representative plant associations of the seasonally dry tropical forest, distributed on western Michoacán and to provide a sintaxonomic classification framework based on the floristic differentiation of the recognized communities and highlight its phytocenotic diversity. Study site and dates: Estado de Michoacán; 20 years. Methods: A total of 82 phytosociological inventories were conducted. Data were submitted to multivariate two-way indicator species analyses to depict plant communities and their ecological affinities. Results: From its analysis and interpretation, nine plant groups were differentiated, of which all but one was given the rank of association, which are Lysilomo acapulcensis–Heliocarpetum terebinthinacei, Ceibo aesculifoliae–Lysilometum divaricatae, Caesalpinio platylobae-Cordietum elaeagnoidis, Cochlospermo vitifolii-Lueheetum candidae, Lysilomo divaricatae-Cordietum elaeagnoidis; Stenocereo quevedonis-Cordietum selerianae, Guazumo ulmifoliae-Cordietum elaeagnoidis¸ Lonchocarpo huetamoensis-Cordietum elaeagnoidis and the community of Spondias purpurea-Cochlospermum vitifolium. Conclusions: Comparative floristic and structural profiles among plant communities permitted us to distinguish their bioclimatic relationships. Diagnostic species representative of all plant associations were selected and used for sintaxonomic nomenclature.  Plant associations were finally array along bioclimatic and altitudinal gradients and showed in arranged phytosociological tables. The plant association/community’descriptions permitted to compare structural physiognomy, floristic composition, ecological affinities, distribution patterns and bioclimatic liaison among them.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jorge Palomo-Kumul ◽  
Mirna Valdez-Hernández ◽  
Gerald A. Islebe ◽  
Manuel J. Cach-Pérez ◽  
José Luis Andrade

AbstractWe evaluated the effect of ENSO 2015/16 on the water relations of eight tree species in seasonally dry tropical forests of the Yucatan Peninsula, Mexico. The functional traits: wood density, relative water content in wood, xylem water potential and specific leaf area were recorded during the rainy season and compared in three consecutive years: 2015 (pre-ENSO conditions), 2016 (ENSO conditions) and 2017 (post-ENSO conditions). We analyzed tree size on the capacity to respond to water deficit, considering young and mature trees, and if this response is distinctive in species with different leaf patterns in seasonally dry tropical forests distributed along a precipitation gradient (700–1200 mm year−1). These traits showed a strong decrease in all species in response to water stress in 2016, mainly in the driest site. Deciduous species had lower wood density, higher predawn water potential and higher specific leaf area than evergreen species. In all cases, mature trees were more tolerant to drought. In the driest site, there was a significant reduction in water status, regardless of their leaf phenology, indicating that seasonally dry tropical forests are highly vulnerable to ENSO. Vulnerability of deciduous species is intensified in the driest areas and in the youngest trees.


Hoehnea ◽  
2018 ◽  
Vol 45 (2) ◽  
pp. 238-306 ◽  
Author(s):  
Rafael Felipe de Almeida

ABSTRACT The taxonomic revision of Amorimia (Malpighiaceae) is presented, including typifications, and descriptions for all accepted species. The genus is endemic to Seasonally Dry Tropical Forests and Rainforests of South America, and its species can be distinguished by morphological details of leaves, indumenta, inflorescences, flowers, and fruits. This study includes an identification key for the subgenera and species of Amorimia, illustrations, distribution maps, conservation risk assessments, and comments on ecology, nomenclature, and taxonomy for all species. Additionally, I provide a key to differentiate Amorimia from the remaining genera of the Malpighioid clade.


2021 ◽  
Vol 8 (3) ◽  
Author(s):  
J. A. Pinedo-Escatel ◽  
G. Moya-Raygoza ◽  
C. H. Dietrich ◽  
J. N. Zahniser ◽  
L. Portillo

Tropical forests cover 7% of the earth's surface and hold 50% of known terrestrial arthropod species. Alarming insect declines resulting from human activities have recently been documented in temperate and tropical ecosystems worldwide, but reliable data from tropical forests remain sparse. The sap-sucking tribe Athysanini is one herbivore group sensitive to anthropogenic perturbation and the largest within the diverse insect family Cicadellidae distributed in America's tropical forests. To measure the possible effects of deforestation and related activities on leafhopper biodiversity, a survey of 143 historic collecting localities was conducted to determine whether species documented in the Mexican dry tropical forests during the 1920s to 1940s were still present. Biostatistical diversity analysis was performed to compare historical to recent data on species occurrences. A data matrix of 577 geographical records was analysed. In total, 374 Athysanini data records were included representing 115 species of 41 genera. Historically, species richness and diversity were higher than found in the recent survey, despite greater collecting effort in the latter. A strong trend in species decline was observed (−53%) over 75 years in this endangered seasonally dry ecosystem. Species completeness was dissimilar between historic and present data. Endemic taxa were significantly less important and represented in the 1920s–1940s species records. All localities surveyed in the dry tropical forest are disturbed and reduced by modern anthropogenic processes. Mexico harbours highly endemic leafhopper taxa with a large proportion of these inhabiting the dry forest. These findings provide important data for conservation decision making and modelling of distribution patterns of this threatened seasonally dry tropical ecosystem.


Author(s):  
Patrick Roberts

The above quote by the German poet, novelist, and painter Herman Hesse highlights the cultural significance of forests in nineteenth- and twentieth-century western culture as the ‘natural’ contrast to growing urban populations and industrial expansion. Hesse’s focus on the ‘ancient’ element of these environments is certainly valid in a tropical context, given that tropical forests are some of the oldest land-based environments on the planet, existing for over one thousand times longer than Homo sapiens (Upchurch and Wolf, 1987; Davis et al., 2005; Ghazoul and Shiel, 2010; Couvreur et al., 2011). This antiquity also makes them one of the richest and most diverse terrestrial ecosystems on the planet (Whitmore, 1998; Ghazoul and Shiel, 2010). Tropical rainforests, for example, contain over half of the world’s existing plant, animal, and insect species (Wilson, 1988). A significant portion of the developed world’s diet today originated in tropical forests—including staples such as squash and yams, spices such as black pepper, cinnamon, cloves, and sugar cane, and fruits including bananas, coconuts, avocados, mangoes, and tomatoes (Iriarte et al., 2007; Roberts et al., 2017a). Tropical forests also often provide ample freshwater for their inhabitants. However, despite popular perceptions of forests, and specifically tropical forests, as uniform, they are, in fact, highly variable across space and time. In tropical evergreen rainforests productivity is often primarily allocated to wood products, meaning that edible plants and animals for human subsistence have been considered lacking, or at least more difficult to extract, relative to more open tropical forest formations (Whitmore, 1998; Ghazoul and Shiel, 2010). Similarly, while evergreen tropical rainforests generally receive significant precipitation and freshwater, seasonally dry tropical forests are subject to sub-annual periods of aridity. Therefore, while archaeologists and anthropologists have tended to see ‘tropical forest’ as a uniform environmental block, it is important to explore the diversity within this category.


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