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Rocha, Andre Medeiros, Marcos Esdras Leite, and Mário Marcos do Espírito-Santo. "MONITORING OF BRAZILIAN DECIDUOUS SEASONAL FOREST BY REMOTE SENSING." Mercator 19, no. 2020 (December 15, 2020): 1–20. http://dx.doi.org/10.4215/rm2020.e19022.
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Among the many characteristics that the Brazilian territory possesses, one precisely excel: the mentioned country hosts the second biggest forest resource of the planet, corresponding for approximately 10% of the total amount of global forest resources. In that scenario, the Seasonally Dry Tropical Forests (SDTF) perform the second less expressive forest type in Brazil, being situated mostly in non-forested biomes, such as Savannas and Scrublands. Thus, its conservation must rely on its correct identification, which becomes difficult because the SDTF areas are generally classified as other vegetation types. Therefore, the present study aimed to perform the land cover-land use monitoring for the years of 2007 and 2016 of the continuous area North of Minas Gerais - South Piauí, with the purpose of evaluating the current situation of Brazilian SDTFs and assessing the main drivers that affect its deforestation and natural regeneration. As a result, the study verified that the significant increase in crop areas and spatial mobility of parturelands contributed decisively for the changes presented by vegetation formations. HOWEVER, such drivers played differentiated roles in losses/gains. Especially, it was concluded that the changes in which deciduous forests have undergone were explained particularly by pasture. The other types of vegetation were also impacted by this class, but with a more incisive participation of the crops. Key-words: Mapping, Deciduous Forests, Remote Sensing, GIS.
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Power, M. J., B. S. Whitney, F. E. Mayle, D. M. Neves, E. J. de Boer, and K. S. Maclean. "Fire, climate and vegetation linkages in the Bolivian Chiquitano seasonally dry tropical forest." Philosophical Transactions of the Royal Society B: Biological Sciences 371, no. 1696 (June 5, 2016): 20150165. http://dx.doi.org/10.1098/rstb.2015.0165.
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South American seasonally dry tropical forests (SDTFs) are critically endangered, with only a small proportion of their original distribution remaining. This paper presents a 12 000 year reconstruction of climate change, fire and vegetation dynamics in the Bolivian Chiquitano SDTF, based upon pollen and charcoal analysis, to examine the resilience of this ecosystem to drought and fire. Our analysis demonstrates a complex relationship between climate, fire and floristic composition over multi-millennial time scales, and reveals that moisture variability is the dominant control upon community turnover in this ecosystem. Maximum drought during the Early Holocene, consistent with regional drought reconstructions, correlates with a period of significant fire activity between 8000 and 7000 cal yr BP which resulted in a decrease in SDTF diversity. As fire activity declined but severe regional droughts persisted through the Middle Holocene, SDTFs, including Anadenanthera and Astronium , became firmly established in the Bolivian lowlands. The trend of decreasing fire activity during the last two millennia promotes the idea among forest ecologists that SDTFs are threatened by fire. Our analysis shows that the Chiquitano seasonally dry biome has been more resilient to Holocene changes in climate and fire regime than previously assumed, but raises questions over whether this resilience will continue in the future under increased temperatures and drought coupled with a higher frequency anthropogenic fire regime. This article is part of the themed issue ‘The interaction of fire and mankind’.
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Reis, Geovany Heitor, Marcela de Castro Nunes Santos Terra, David Yue Phin Tng, Deborah Mattos Guimaraes Apgaua, Polyanne Aparecida Coelho, Rubens Manoel dos Santos, and Yule Roberta Ferreira Nunes. "Temporal vegetation changes in a seasonally dry tropical forest enclave in an ecotonal region between savanna and semiarid zones of Brazil." Australian Journal of Botany 65, no. 1 (2017): 85. http://dx.doi.org/10.1071/bt16188.
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Seasonally dry tropical forests (SDTFs) comprise a globally significant biome for biodiversity and conservation. Geographically, Brazilian SDTFs are primarily located within the country’s semiarid region (the Caatinga domain) in north-eastern Brazil. However, poorly studied and disjunct SDTF enclaves can occur within other regions, inside other Brazilian phytogeographical domains of vegetation such as savannas (i.e. the Cerrado domain) in central Brazil. These enclaves provide an opportunity to examine natural and non-anthropogenic edge effects on such vegetation. In 2007 and 2014, we studied a 120-ha SDTF enclave in the municipality of Januária in northern Minas Gerais, Brazil, to understand its (1) floristic composition and soil correlates, and (2) temporal variations in diversity, structure and dynamics. Three sets of 10 400-m2 plots were used to compare the vegetation at 0 m (edge), 100 m (middle) and 200 m (inner) into the forest. The edge plots were compositionally dissimilar from the interior plots because of soil fertility and soil textural gradients. Paradoxically also, the inner plots exhibited less stable vegetation-dynamic patterns than did both the middle and the edge plots, possibly owing to natural temporal fluctuations in vegetation dynamics. Overall, the SDTF enclave exhibited high diversity and structural complexity, likely because of its geographical setting within a matrix of savanna. These results highlight a conservation priority for further studies on such SDTF enclaves throughout their range.
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Saenz-Pedroza, Irving, Richard Feldman, Casandra Reyes-García, Jorge A. Meave, Luz Maria Calvo-Irabien, Filogonio May-Pat, and Juan M. Dupuy. "Seasonal and successional dynamics of size-dependent plant demographic rates in a tropical dry forest." PeerJ 8 (September 14, 2020): e9636. http://dx.doi.org/10.7717/peerj.9636.
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Tropical forests are globally important for biodiversity conservation and climate change mitigation but are being converted to other land uses. Conversion of seasonally dry tropical forests (SDTF) is particularly high while their protection is low. Secondary succession allows forests to recover their structure, diversity and composition after conversion and subsequent abandonment and is influenced by demographic rates of the constituent species. However, how these rates vary between seasons for different plant sizes at different successional stages in SDTF is not known. The effect of seasonal drought may be more severe early in succession, when temperature and radiation are high, while competition and density-dependent processes may be more important at later stages, when vegetation is tall and dense. Besides, the effects of seasonality and successional stage may vary with plant size. Large plants can better compete with small plants for limiting resources and may also have a greater capacity to withstand stress. We asked how size-dependent density, species density, recruitment and mortality varied between seasons and successional stages in a SDTF. We monitored a chronosequence in Yucatan, Mexico, over six years in three 0.1 ha plots in each of three successional stages: early (3–5 years-old), intermediate (18–20 years-old) and advanced (>50 years-old). Recruitment, mortality and species gain and loss rates were calculated from wet and dry season censuses separately for large (diameter > 5 cm) and small (1–5 cm in diameter) plants. We used linear mixed-effects models to assess the effects of successional stage, seasonality and their changes through time on demographic rates and on plant and species density. Seasonality affected demographic rates and density of large plants, which exhibited high wet-season recruitment and species gain rates at the early stage and high wet-season mortality at the intermediate stage, resulting in an increase in plant and species density early in succession followed by a subsequent stabilization. Small plant density decreased steadily after only 5 years of land abandonment, whereas species density increased with successional stage. A decline in species dominance may be responsible for these contrasting patterns. Seasonality, successional stage and their changes through time had a stronger influence on large plants, likely because of large among-plot variation of small plants. Notwithstanding the short duration of our study, our results suggest that climate-change driven decreases in rainy season precipitation may have an influence on successional dynamics in our study forest as strong as, or even stronger than, prolonged or severe droughts during the dry season.
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Apgaua, Deborah Mattos Guimarães, Polyanne Aparecida Coelho, Rubens Manoel dos Santos, Paola Ferreira Santos, and Ary Teixeira de Oliveira-Filho. "Tree community structure in a seasonally dry tropical forest remnant, Brazil." CERNE 20, no. 2 (June 2014): 173–82. http://dx.doi.org/10.1590/01047760.201420021540.
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Most studies on Seasonally Dry Tropical Forests (SDTFs) investigate phytogeographic patterns and floristic connections of this disjunct biome. However, little is known about the structural characteristics of SDTFs. We aimed to describe the structure of a SDTF in an ecotonal area between the Cerrado and Caatinga domains. In total, 79 tree species were recorded, and high values of Shannon diversity index (3.6 nats/individual) and equability (0.83) were observed. The diameter distribution for the species with higher cover values and for the entire community did not exhibit a reverse-J shaped distribution, which indicates the occurrence of different growth strategies and ecological adaptations to water stress. The results did not indicate the formation of floristic groups, as the high soil fertility in the study area results in a homogeneous environment. The structural characteristics of the study area associated with the soil composition highlight its importance for conservation and emphasize the need for community structure studies in SDTFs.
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Rodrigues, PMS, JO Silva, PV Eisenlohr, and CEGR Schaefer. "Climate change effects on the geographic distribution of specialist tree species of the Brazilian tropical dry forests." Brazilian Journal of Biology 75, no. 3 (August 25, 2015): 679–84. http://dx.doi.org/10.1590/1519-6984.20913.
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AbstractThe aim of this study was to evaluate the ecological niche models (ENMs) for three specialist trees (Anadenantheracolubrina, Aspidosperma pyrifolium and Myracrodruon urundeuva) in seasonally dry tropical forests (SDTFs) in Brazil, considering present and future pessimist scenarios (2080) of climate change. These three species exhibit typical deciduousness and are widely distributed by SDTF in South America, being important in studies of the historical and evolutionary processes experienced by this ecosystem. The modeling of the potential geographic distribution of species was done by the method of maximum entropy (Maxent).We verified a general expansion of suitable areas for occurrence of the three species in future (c.a., 18%), although there was reduction of areas with high environmental suitability in Caatinga region. Precipitation of wettest quarter and temperature seasonality were the predictor variables that most contributed to our models. Climatic changes can provide more severe and longer dry season with increasing temperature and tree mortality in tropics. On this scenario, areas currently occupied by rainforest and savannas could become more suitable for occurrence of the SDTF specialist trees, whereas regions occupied by Caatinga could not support the future level of unsustainable (e.g., aridity). Long-term multidisciplinary studies are necessary to make reliable predictions of the plant’s adaptation strategies and responses to climate changes in dry forest at community level. Based on the high deforestation rate, endemism and threat, public policies to minimize the effects of climate change on the biodiversity found within SDTFs must be undertaken rapidly.
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ANDRADE, EUNICE MAIA DE, GILBERTO QUEVEDO ROSA, ALDENIA MENDES MASCENA DE ALMEIDA, ANTONIO GIVANILSON RODRIGUES DA SILVA, and MARIA GINA TORRES SENA. "RAINFALL REGIME ON FINE ROOT GROWTH IN A SEASONALLY DRY TROPICAL FOREST." Revista Caatinga 33, no. 2 (April 2020): 458–69. http://dx.doi.org/10.1590/1983-21252020v33n218rc.
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ABSTRACT Seasonally dry tropical forests (SDTF) usually present dry seasons of eight or more months. Considering the concerns about the resilience of SDTF to climate changes, the objective of this study was to evaluate the effect of the rainfall regime on fine root growth in a SDTF. The experiment started at the end of the wet season (July 2015), when fine roots were evaluated and ingrowth cores were implemented. The temporal growth of fine roots in the 0-30 cm soil layer was monitored, considering the 0-10, 10-20, and 20-30 cm sublayers, through six samplings from November 2015 to July 2017. The characteristics evaluated were fine root biomass, fine root length, fine root specific length, and fine root mean diameter. The significances of the root growths over time and space were tested by the Kruskal-Wallis test (p<0.05). Fine roots (Ø<2 mm) were separated and dried in an oven (65 °C) until constant weight. The root length was determined using the Giaroots software. The fine root biomass in July 2015 was 7.7±5.0 Mg ha-1 and the length was 5.0±3.2 km m-2. Fine root growth in SDTF is strongly limited by dry periods, occurring decreases in biomass and length of fine roots in all layers evaluated. Fine root growth occurs predominantly in rainy seasons, with fast response of the root system to rainfall events, mainly in root length.
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Maia Andrade, Eunice, Wilner Valbrun, Aldênia Mendes Mascena de Almeida, Gilberto Rosa, and Antonio Givanilson Rodrigues da Silva. "Land-Use Effect on Soil Carbon and Nitrogen Stock in a Seasonally Dry Tropical Forest." Agronomy 10, no. 2 (January 22, 2020): 158. http://dx.doi.org/10.3390/agronomy10020158.
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Total organic carbon (TOC) and total nitrogen (TN) concentration in the soil are an indicator of soil degradation. To understand how land-use may impact these concentrations in seasonally dry tropical forests (SDTF), we analyzed the effect of four land-uses on TOC stocks (STK.TOC) and TN stocks (STK.TN) in a semi-arid region of Brazil. Soil samples were collected in 12 trenches (three sites × four land-uses—dense caatinga (DC), open caatinga (OC), pasture (PA) and agriculture (AG)), in the 0–10; 10–20 and 20–30 cm layers or as far as the bedrock. The data were compared by the Kruskal–Wallis test (p ≤ 0.05) and similarity investigated by cluster analysis. STK.TOC and STK.TN the surface layer (0–10 cm) showed no significant difference (p ≤ 0.05) between the DC; OC and PA land-uses. The similarity in STK.TOC and STK.TN values between DC, OC and PA, indicate that it is possible to explore SDTF to produce biomass and protein by adopting open caatinga and pasture land uses on Neosols with very low TOC stocks. The greatest reduction in STK.TOC and STK.TN in the agriculture land-use may lead to soil degradation and contribute to the addition of CO2 to the atmosphere.
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Mogni, V. Y., L. J. Oakley, and D. E. Prado. "THE DISTRIBUTION OF WOODY LEGUMES IN NEOTROPICAL DRY FORESTS: THE PLEISTOCENE ARC THEORY 20 YEARS ON." Edinburgh Journal of Botany 72, no. 1 (December 3, 2014): 35–60. http://dx.doi.org/10.1017/s0960428614000298.
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The Pleistocene Arc Theory (PAT) suggests that present-day disjunct fragments of dry forests in central tropical South America give evidence of a previously more continuous distribution during the Pleistocene that has been disrupted by dry-cold vs. humid-warm climatic cycles. This Arc extends from NE Brazil to NE Argentina and eastern Paraguay, through the Chiquitanía to NW Argentina and SW Bolivia and into the dry inter-Andean valleys in Peru and Ecuador, with intrusions into the Great Chaco. Seasonally Dry Tropical Forests (SDTFs) are floristically and physiognomically dominated by woody legumes, mostly deciduous in the dry season. In the last two decades field collection and research on legume taxa has greatly increased, with a significant number of taxonomic revisions and molecular phylogenetic studies, together with some paleoclimatic modelling studies. The evidence accumulated in the last 23 years has confirmed the integrity of the Chaco and Caatingas phytogeographical provinces, with an impressive and increasing level of botanical endemism discovered. The PAT pattern has also been supported, specifically through the mapping of five selected woody Leguminosae species (Anadenanthera colubrina, Enterolobium contortisiliquum, Pterogyne nitens, Amburana cearensis and Piptadenia viridiflora). The pre-existing nuclei of South American SDTF (Caatingas, Misiones and Piedmont) are now increased to four with the postulation of the Chiquitanía Nucleus in south-eastern Bolivia and bordering Paraguay. Some new endemisms are compiled from recent literature and mapped for the Misiones and Chiquitanía nuclei. The need for more botanical collections and further taxonomic, phylogenetic and demographic studies of South American legumes is emphasised.
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KÜLKAMP, JOSIMAR, JOÃO R. V. IGANCI, INÊS CORDEIRO, and JOSÉ FERNANDO A. BAUMGRATZ. "Ditaxis (Euphorbiaceae) from the Brazilian Caatinga, including a new species." Phytotaxa 455, no. 2 (August 10, 2020): 152–60. http://dx.doi.org/10.11646/phytotaxa.455.2.6.
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Ditaxis is a Neotropical genus with approximately 50 species, most of them in seasonally dry tropical forests of Brazil, Central America and the Antilles. The Brazilian Caatinga, the largest area of SDTF in South America, harbors three endemic species of Ditaxis, including the new Ditaxis grazielae, hereby described and illustrated. The new species is known from a few localities in the state of Bahia. We provide an identification key for the species occurring in the Caatinga, as well as comments on habitat, distribution and phenology. We also present amended descriptions and typifications for Ditaxis desertorum and D. malpighiacea, and propose D. gardneri as synonym of D. desertorum.
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Apgaua, Deborah Mattos Guimarães, Rubens Manoel dos Santos, Diego Gualberto Sales Pereira, Gisele Cristina de Oliveira Menino, Gabriela Gomes Pires, Marco Aurélio Leite Fontes, and David Yue Phin Tng. "Beta-diversity in seasonally dry tropical forests (SDTF) in the Caatinga Biogeographic Domain, Brazil, and its implications for conservation." Biodiversity and Conservation 23, no. 1 (November 26, 2013): 217–32. http://dx.doi.org/10.1007/s10531-013-0599-9.
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Ceccon, Eliane, Anayeli Almazo-Rogel, Esperanza Martínez-Romero, and Ivonne Toledo. "The effect of inoculation of an indigenous bacteria on the early growth of Acacia farnesiana in a degraded area." CERNE 18, no. 1 (March 2012): 49–57. http://dx.doi.org/10.1590/s0104-77602012000100007.
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Restoration of native vegetation and fuelwood production are important environmental pending goals for Mexico, where years of wrong management practices resulted in ecosystemic degradation and fuelwood scarcity. In degraded areas, native rhizobial strains are often undetectable, therefore, the restoration of natural vegetation associated with an effective nodulation of the leguminous trees is mostly appropriate. Sinorhizobium americanum is a native nitrogen-fixing bacteria isolated from nodules of the native Acacia species in the region. Acacia farnesiana is a multipurpose leguminous shrub from Mexican seasonally dry tropical forests (SDTF). In this study we analyzed the effect of inoculation with S. americanum on A. farnesiana growth in a greenhouse and in a very degraded area and compared with non-inoculated seedlings. In a greenhouse, we measured the biomass dry weight of different parts of the plant, using destructive sampling after 15, 20, 30, 45 and 120 days of growth. We also calculated the relative growth rate (RGR) and the resources allocation (root/shoot weight ratio and root length/root dry weight) of seedlings. In a degraded area we measured the seedling length and survival and calculated the RGR. In the greenhouse and in the degraded area, the inoculation positively affected the growth of seedlings. However in the greenhouse, the inoculation did not have effect on resource allocation patterns. Therefore, the inoculation with Sinorhizobium americanum could improve the A. farnesiana growth and the re-establishment of important plant-soil interactions in degraded areas, being a recommendable technique for land restoration and the improvement of fuelwood production.
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Bueno, M. L., D. R. Neves, A. T. Oliveira Filho, C. R. Lehn, and J. A. Ratter. "A STUDY IN AN AREA OF TRANSITION BETWEEN SEASONALLY DRY TROPICAL FOREST AND MESOTROPHIC CERRADÃO, IN MATO GROSSO DO SUL, SOUTHWESTERN BRAZIL." Edinburgh Journal of Botany 70, no. 3 (October 18, 2013): 469–86. http://dx.doi.org/10.1017/s0960428613000164.
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This study describes the tree vegetation and soils occurring in a seasonally dry tropical forest (SDTF) and mesotrophic cerradão transition in southwestern Brazil. All trees ≥ 5 cm diameter were measured in 20 plots of 20 × 25 m, 10 in SDTF, and 10 in mesotrophic cerradão. Ten soil samples of 0−20 cm depth were made per plot and mixed in plot groups to produce two composite samples. A total of 71 species was recorded.Anadenanthera colubrinahad the highest importance values in both formations. Differences in soil fertility were found between SDTFs (eutrophic soils) and mesotrophic cerradão (mesotrophic soils). A non-metric multidimensional scaling and cluster analysis confirmed the soil fertility segregation, and also showed an agreement between soil fertility and variance in species composition gradients. The mesotrophic cerradão showed higher species richness since it also includes many species typical of more dystrophic and open forms of Cerrado.
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Andrade, Eunice Maia, Maria Elinalda Ribeiro Costa, Júlio César Neves dos Santos, Helba Araujo De Queiroz Palácio, and Jacques Carvalho Ribeiro Filho. "Plant cover and hydrological response in a seasonally dry tropical forest (SDTF)." REVISTA AGRO@MBIENTE ON-LINE 11, no. 4 (October 3, 2017): 258. http://dx.doi.org/10.18227/1982-8470ragro.v11i4.4556.
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Marcelo-Peña, J. L., I. Huamantupa, T. Särkinen, and M. Tomazello. "IDENTIFYING CONSERVATION PRIORITY AREAS IN THE MARAÑÓN VALLEY (PERU) BASED ON FLORISTIC INVENTORIES." Edinburgh Journal of Botany 73, no. 1 (November 24, 2015): 95–123. http://dx.doi.org/10.1017/s0960428615000281.
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In this study, we report species diversity and endemism of the poorly known but highly diverse Seasonally Dry Tropical Forest (SDTF) flora of the Marañón valley in northern Peru. We characterise woody vascular plant species diversity across the valley in order to define the conservation value of the area at national and international level. Based on 32 rapid botanical inventories, 92 plots of 50 × 20 m, and a herbarium study across local and international herbaria, we report 440 woody vascular plant species of which 143 (33%) are endemic to the valley. Two centres of endemism within the valley are identified, each with clear elevational zonation of diversity. Data show that the Marañón valley is a good representative of Peruvian SDTFs as a whole, with an average of 56% SDTF species and 78% SDTF genera found in the one valley. The results show that there is wide variation in the set of dominant species across the valley, and that many local endemics are locally abundant unlike in neighbouring SDTFs where the dominant species are all geographically widespread. Our results demonstrate that the Marañón includes a rare combination of both nationally representative yet globally unique plant species, which makes the valley an ideal conservation target. The high level of endemism structured within elevational zones implies that conservation areas should be established across elevational zones in order to maximise the protection of this globally unique flora.
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Ceccon, Eliane, Pilar Huante, and Emanuel Rincón. "Abiotic factors influencing tropical dry forests regeneration." Brazilian Archives of Biology and Technology 49, no. 2 (March 2006): 305–12. http://dx.doi.org/10.1590/s1516-89132006000300016.
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Tropical dry forests represent nearly half the tropical forests in the world and are the ecosystems registering the greatest deterioration from the anthropogenic exploitation of the land. This paper presents a review on the dynamics of tropical dry forests regeneration and the main abiotic factors influencing this regeneration, such as seasonal nature, soil fertility and humidity, and natural and anthropic disturbances. The main purpose is to clearly understand an important part of TDF succession dynamics.
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Valbrun, W., E. M. de Andrade, A. M. M. de Almeida, and E. L. de Almeida. "Carbon and Nitrogen Stock Under Different Types of Land Use in a Seasonally Dry Tropical Forest." Journal of Agricultural Science 10, no. 12 (November 15, 2018): 479. http://dx.doi.org/10.5539/jas.v10n12p479.
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The aim of this study, was to analyse the effect of cover vegetation change on stocks of Total Organic Carbon (ST.TOC) and Total Nitrogen (ST.TN) in soils of a Seasonally Dry Tropical Forest in the Brazilian semi-arid region. The study was carried out on three farms located on a typical Orthic Chromic Luvisol in an SDTF. Soil samples were collected from trenches, 70 × 70 cm in size, in the 0-10, 10-20, 20-30, 30-40, 40-60 and 60-80 cm layers, under four types of land use: dense Caatinga (DC), open Caatinga (OC), agriculture (AG) and pasture (PA). The following attributes were evaluated: bulk density, Total Organic Carbon (TOC), Total Nitrogen (TN), ST.TOC and ST.TN. The data were compared using the Mann-Whitney test (p ≤ 0.05). Hierarchical Grouping Analysis (HGA) was used to understand the behaviour of the attributes evaluated between cover vegetation types. Using HGA resulted in the formation of three distinct groups for the types of land use under investigation. The highest mean values for ST.TOC (11.29 Mg ha-1) and ST.TN (3.36 Mg ha-1) were found in CD and CA. The changes in land use in the SDTF had an effect on ST.TOC and ST.TN. It is therefore necessary to adopt strategies and strengthen conservation practices in areas of agricultural and pasture, and reduce the process of degradation and further the process of recovery in these areas. Such action will reduce the loss of C and N, and increase the levels and stocks of TOC and TN.
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Cao, Sen, and Arturo Sanchez-Azofeifa. "Modeling seasonal surface temperature variations in secondary tropical dry forests." International Journal of Applied Earth Observation and Geoinformation 62 (October 2017): 122–34. http://dx.doi.org/10.1016/j.jag.2017.06.008.
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Reich, P. B. "Phenology of tropical forests: patterns, causes, and consequences." Canadian Journal of Botany 73, no. 2 (February 1, 1995): 164–74. http://dx.doi.org/10.1139/b95-020.
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Leaf phenology of tropical forests is distinct from other biomes. Unlike the marked temperature-related periodicity of temperate forests, development tends to be continuous in aseasonal lowland tropical rain forests and becomes more episodic in response to increasing annual drought in tropical dry forests. Hence, in tropical rain forests, foliar development (production, senescence, and longevity) is largely under internal rather than environmental control. In contrast, tropical forests with marked annual dry seasons display associated seasonality of leaf production and shedding. This developmental seasonality can be explained by overlaying the influence of seasonality on trees' internally regulated development and appears to be controlled by acclimative physiological processes and not by sensitivity to photo-, thermo-periodic, or direct environmental cues. Consequences of tropical phenology stem from both the variety of leaf and species ecophysiological types common to a given moisture regime and their relative synchrony of development, and include the following: larger diversity of ecophysiological species types in rain than dry forests; differential rates of herbivory in dry than wet seasons and for synchronous versus asynchronous leaf flushes; ecosystems with greater canopy foliar mass per hectare in rain than dry forests; and several leaf adaptations perhaps unique to tropical forests, such as delayed greening and seasonal leaf phenotypes. Tropical forests may vary in sensitivity to predicted climate change. Phenology of rain forests should change little unless water balance changes markedly, and developmental events in rain forests may be relatively insensitive to moderate changes in CO2 or temperature. Phenology of dry forests could be more sensitive, and in opposite directions, to elevated CO2 and temperatures. Elevated CO2 might delay the onset of leaf shedding and stimulate longer life span if stand level transpiration is reduced, whereas higher temperatures could lead to more rapid water depletion, longer leafless periods, and more strongly synchronized phenology. Key words: tropical forests, phenology, leaf life span, herbivory.
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Monterrubio-Rico, Tiberio C., Juan F. Charre-Medellín, Marco Z. Pérez-Martínez, and Eduardo Mendoza. "Use of remote cameras to evaluate ocelot (Leopardus pardalis) population parameters in seasonal tropical dry forests of central-western Mexico." Mammalia 82, no. 2 (February 23, 2018): 113–23. http://dx.doi.org/10.1515/mammalia-2016-0114.
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AbstractThe ocelot is one of the most studied felid species in the neotropics yet most of our current knowledge comes from tropical rain forests and protected areas. Therefore, we lack a comprehensive understanding on how the species abundance varies in terms of ecological parameters across its full distribution range. This is particularly true for the species population in the Northern Hemisphere, as data of ocelot populations occurring in tropical dry forests are scarce. In this study, we focused on: a) generating population data (density and sex ratios), based on camera-trapping, for ocelot occurring in the vast and understudied tropical dry forest of the western Pacific of Mexico. b) Comparing the variation in species abundance and density across its distribution range, including a larger set of studies from the Northern Hemisphere, contrasting parameters between rain forests and tropical seasonal ecosystems and re-examining the assumed relationship between precipitation and ocelot abundance. Overall, we identified 17 ocelots in our study sites and estimated an average density of 23.7 individuals (ind) per 100 km2with a female to male ratio >1. No significant differences in ocelot density was found between seasonal tropical forests and rain forests studies (Wilcoxon test, W=71, p=0.7675). Moreover, we found no support for the relation between ocelot density and precipitation (only when restricting our analysis to rain forest data the fit of the regression model was close to be significant, R2=0.2463, p=0.07107). Our results indicate that tropical seasonal ecosystems and dry forest in particular, may present ocelot population with similar levels of abundance than tropical rain forests. We observed that precipitation is a poor predictor of ocelot abundance. In our study, we observed that overall local ecological factors (e.g. prey abundance and interspecific interactions) influenced the spatial and temporal abundance of ocelots.
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Calvo-Rodriguez, Sofia, G. Sánchez-Azofeifa, Sandra Durán, Mario Do Espírito-Santo, and Yule Ferreira Nunes. "Dynamics of Carbon Accumulation in Tropical Dry Forests under Climate Change Extremes." Forests 12, no. 1 (January 19, 2021): 106. http://dx.doi.org/10.3390/f12010106.
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We analyze here how much carbon is being accumulated annually by secondary tropical dry forests (TDFs) and how structure, composition, time since abandonment, and climate can influence the dynamics of forest carbon accumulation. The study was carried out in Santa Rosa National Park in Guanacaste province, Costa Rica and Mata Seca State Park in Minas Gerais, Brazil. Total carbon storage and carbon accumulation were obtained for both sites from the sum of the aboveground carbon and belowground carbon gain plus the annual litterfall. Carbon accumulation of these TDFs varied from 2.6 Mg C ha−1 y−1 to 6.3 Mg C ha−1 y−1, depending on the age of the forest stands. Time since abandonment and number of stems per plot were the best predictors for carbon storage, annual carbon gains, and losses. Mortality rates and carbon losses were also associated with seasonal climate variability. We found significant correlations between tree mortality, carbon losses and mean seasonal temperature, mean seasonal precipitation, potential evapotranspiration, and the Oceanic Niño Index. Carbon dynamics in tropical dry forests are driven by time since abandonment and forest structure; however, rising temperature and El Niño Southern Oscillation (ENSO) events can have a significant impact on tree mortality and carbon losses. Depending on their location and land-use history, some dry forests are more impacted by climatic extremes than others, and differences between secondary stages are expected.
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Gonçalves, Gabriela Silva Ribeiro, Pablo Vieira Cerqueira, Leandro Schlemmer Brasil, and Marcos Pérsio Dantas Santos. "The role of climate and environmental variables in structuring bird assemblages in the Seasonally Dry Tropical Forests (SDTFs)." PLOS ONE 12, no. 4 (April 25, 2017): e0176066. http://dx.doi.org/10.1371/journal.pone.0176066.
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Sánchez, Octavio, Mauricio Quesada, Rodolfo Dirzo, and Carl D. Schlichting. "A field experiment to determine the effect of dry-season irrigation on vegetative and reproductive traits in the wet-deciduous tree Bonellia nervosa." Journal of Tropical Ecology 36, no. 1 (December 23, 2019): 29–35. http://dx.doi.org/10.1017/s0266467419000324.
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AbstractSeasonally dry tropical forests (SDTFs) stand out by the diversity of phenological patterns used by plants to deal with dry periods. Although the predominant phenological pattern is dry deciduousness, in Mesoamerican SDTFs the heliophilous tree species Bonellia (formerly Jacquinia) nervosa displays an unusual inverted leaf phenology, producing and holding leaves through the dry season while becoming deciduous in the rainy season. Applying a dry season irrigation field experiment (no water, low watering, high watering), we studied the consequences of contrasting water availability from a phenological plasticity response perspective. Contrary to our expectations, our results show no effect of irrigation treatment on leaf phenology. In addition, mid-day twig water potential showed no significant differences across treatments, but reproductive phenological responses varied among treatments: canopy flowering per cent decreased gradually until the beginning of the wet season in all treatments; meanwhile canopy fruit per cent showed a significant decline under low irrigation. Finally, non-structural carbohydrate concentration (starch) was significantly higher in the high irrigation treatment. Our results showed that inverted leaf phenology remains unaffected regardless of supplemental water availability, and suggest a reallocation of non-structural carbohydrates to fruits and seeds in high-irrigation treatments. Given the current and expected increase in extreme drought events, investigations on the responses of trees of different phenologies, including those of inverted leafing such as Bonellia nervosa, are warranted.
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De Weirdt, M., H. Verbeeck, F. Maignan, P. Peylin, B. Poulter, D. Bonal, P. Ciais, and K. Steppe. "Seasonal leaf dynamics for tropical evergreen forests in a process based global ecosystem model." Geoscientific Model Development Discussions 5, no. 1 (February 24, 2012): 639–81. http://dx.doi.org/10.5194/gmdd-5-639-2012.
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Abstract. The influence of seasonal phenology in tropical humid forests on canopy photosynthesis remains poorly understood and its representation in global vegetation models highly simplified, typically with no seasonal variability of canopy leaf area properties taken into account. However, recent flux tower and remote sensing studies suggest that seasonal phenology in tropical rainforests exerts a large influence over carbon and water fluxes, with feedbacks that can significantly influence climate dynamics. A more realistic description of the underlying mechanisms that drive seasonal tropical forest photosynthesis and phenology could improve the correspondence of global vegetation model outputs with the wet-dry season biogeochemical patterns measured at flux tower sites. Here, we introduce a leaf Net Primary Production (NPP) based canopy dynamics scheme for evergreen tropical forests in the global terrestrial ecosystem model ORCHIDEE and validated the new scheme against in-situ carbon flux measurements. Modelled Gross Primary Productivity (GPP) patterns are analyzed in details for a flux tower site in French Guiana, in a forest where the dry season is short and where the vegetation is considered to have developed adaptive mechanisms against drought stress. By including leaf litterfall seasonality and a coincident light driven leaf flush and seasonal change in photosynthetic capacity in ORCHIDEE, modelled carbon and water fluxes more accurately represent the observations. The fit to GPP flux data was substantially improved and the results confirmed that by modifying canopy dynamics to benefit from increased light conditions, a better representation of the seasonal carbon flux patterns was made.
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Morffi-Mestre, Hernán, Gregorio Ángeles-Pérez, Jennifer S. Powers, José Luis Andrade, Astrid Helena Huechacona Ruiz, Filogonio May-Pat, Francisco Chi-May, and Juan Manuel Dupuy. "Multiple Factors Influence Seasonal and Interannual Litterfall Production in a Tropical Dry Forest in Mexico." Forests 11, no. 12 (November 24, 2020): 1241. http://dx.doi.org/10.3390/f11121241.
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Litterfall production plays a fundamental role in the dynamics and function of tropical forest ecosystems, as it supplies 70–80% of nutrients entering the soil. This process varies annually and seasonally, depending on multiple environmental factors. However, few studies spanning several years have addressed the combined effect of climate variables, successional age, topography, and vegetation structure in tropical dry forests. In this study, we evaluated monthly, seasonal, and annual litterfall production over a five-year period in semideciduous dry forests of different successional ages growing on contrasting topographic conditions (sloping or flat terrain) in Yucatan, Mexico. Its relationship with climate and vegetation structural variables were also analyzed using multiple linear regression and generalized linear models. Litterfall was measured monthly in 12 litterfall traps of 0.5 m2 in three sampling clusters (sets of four 400 m2 sampling plots) established in forests of five successional age classes, 3–5, 10–17, 18–25, 60–79, and >80 years (in the latter two classes either on slopping or on flat terrain), for a total of 15 sampling clusters and 180 litterfall traps. Litterfall production varied between years (negatively correlated with precipitation), seasons (positively correlated with wind speed and maximum temperature), and months (negatively correlated with relative humidity) and was higher in flat than in sloping sites. Litterfall production also increased with successional age until 18–25 years after abandonment, when it attained values similar to those of mature forests. It was positively correlated with the aboveground biomass of deciduous species but negatively correlated with the basal area of evergreen species. Our results show a rapid recovery of litterfall production with successional age of these forests, which may increase with climate changes such as less precipitation, higher temperatures, and higher incidence of hurricanes.
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Mondal, Nandita, and Raman Sukumar. "Characterising weather patterns associated with fire in a seasonally dry tropical forest in southern India." International Journal of Wildland Fire 23, no. 2 (2014): 196. http://dx.doi.org/10.1071/wf13002.
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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.
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Gao, Yan, Jonathan V. Solórzano, Alexander Quevedo, and Jaime Octavio Loya-Carrillo. "How BFAST Trend and Seasonal Model Components Affect Disturbance Detection in Tropical Dry Forest and Temperate Forest." Remote Sensing 13, no. 11 (May 21, 2021): 2033. http://dx.doi.org/10.3390/rs13112033.
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Time series analysis has gained popularity in forest disturbance monitoring thanks to the availability of satellite and airborne remote sensing images and the development of different time series methods for change detection. Previous research has focused on time series data noise reduction, the magnitude of breakpoints, and accuracy assessment; however, few have looked in detail at how the trend and seasonal model components contribute to disturbance detection in different forest types. Here, we use Landsat time series images spanning 1994–2018 to map forest disturbance in a western Pacific area of Mexico, where both temperate and tropical dry forests have been subject to severe deforestation and forest degradation processes. Since these two forest types have distinct seasonal characteristics, we investigate how trend and seasonal model components, such as the goodness-of-fit (R2), magnitude of change, amplitude, and model length in a stable historical period, affect forest disturbance detection. We applied the Breaks For Additive Season and Trend Monitor (BFAST) algorithm and after accuracy assessment by stratified random sample points, and we obtained 68% and 86% of user accuracy and 75.6% and 86% of producer’s accuracy in disturbance detection, in tropical dry forests and temperate forests, respectively. We extracted the noncorrelated trend and seasonal model components R2, magnitude, amplitude, length of the stable historical period, and percentage of pixels with NA and tested their effects on disturbance detection employing forest-type specific logistic regression. Our results showed that, for all forests combined, the amplitude and stable historical period length contributed to disturbance detection. While for tropical dry forest alone, amplitude was the main predictor, and for the temperate forest alone, the stable historical period length contributed most to the prediction, although it was not statistically significant. These findings provide insights for improving the results of forest disturbance detection in different forest types.
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Chave, J., D. Navarrete, S. Almeida, E. Álvarez, L. E. O. C. Aragão, D. Bonal, P. Châtelet, et al. "Regional and seasonal patterns of litterfall in tropical South America." Biogeosciences 7, no. 1 (January 5, 2010): 43–55. http://dx.doi.org/10.5194/bg-7-43-2010.
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Abstract. The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91 Mg ha−1 yr−1 (mean ± standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg ha−1 yr−1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91 Mg ha−1 yr−1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg ha−1 yr−1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40 Mg ha−1 yr−1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.
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Zou, Lidong, Sen Cao, Anzhou Zhao, and Arturo Sanchez-Azofeifa. "Assessing the Temporal Response of Tropical Dry Forests to Meteorological Drought." Remote Sensing 12, no. 14 (July 21, 2020): 2341. http://dx.doi.org/10.3390/rs12142341.
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Due to excessive human disturbances, as well as predicted changes in precipitation regimes, tropical dry forests (TDFs) are susceptible to meteorological droughts. Here, we explored the response of TDFs to meteorological drought by conducting temporal correlations between the MODIS-derived normalized difference vegetation index (NDVI) and land surface temperature (LST) to a standardized precipitation index (SPI) between March 2000 and March 2017 at the Santa Rosa National Park Environmental Monitoring Super Site (SRNP-EMSS), Guanacaste, Costa Rica. We conducted this study using monthly and seasonal scales. Our results indicate that the NDVI and LST are largely influenced by seasonality, as well as the magnitude, duration, and timing of precipitation. We find that greenness and evapotranspiration are highly sensitive to precipitation when TDFs suffer from long-term water deficiency, and they tend to be slightly resistant to meteorological drought in the wet season. Greenness is more resistant to short-term rainfall deficiency than evapotranspiration, but greenness is more sensitive to precipitation after a period of rainfall deficiency. Precipitation can still strongly influence evapotranspiration on the canopy surface, but greenness is not controlled by the rainfall, but rather phenological characteristics when leaves begin to senesce.
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Tang, Hao, and Ralph Dubayah. "Light-driven growth in Amazon evergreen forests explained by seasonal variations of vertical canopy structure." Proceedings of the National Academy of Sciences 114, no. 10 (February 21, 2017): 2640–44. http://dx.doi.org/10.1073/pnas.1616943114.
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Light-regime variability is an important limiting factor constraining tree growth in tropical forests. However, there is considerable debate about whether radiation-induced green-up during the dry season is real, or an apparent artifact of the remote-sensing techniques used to infer seasonal changes in canopy leaf area. Direct and widespread observations of vertical canopy structures that drive radiation regimes have been largely absent. Here we analyze seasonal dynamic patterns between the canopy and understory layers in Amazon evergreen forests using observations of vertical canopy structure from a spaceborne lidar. We discovered that net leaf flushing of the canopy layer mainly occurs in early dry season, and is followed by net abscission in late dry season that coincides with increasing leaf area of the understory layer. Our observations of understory development from lidar either weakly respond to or are not correlated to seasonal variations in precipitation or insolation, but are strongly related to the seasonal structural dynamics of the canopy layer. We hypothesize that understory growth is driven by increased light gaps caused by seasonal variations of the canopy. This light-regime variability that exists in both spatial and temporal domains can better reveal the drought-induced green-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.
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De Weirdt, M., H. Verbeeck, F. Maignan, P. Peylin, B. Poulter, D. Bonal, P. Ciais, and K. Steppe. "Seasonal leaf dynamics for tropical evergreen forests in a process-based global ecosystem model." Geoscientific Model Development 5, no. 5 (September 6, 2012): 1091–108. http://dx.doi.org/10.5194/gmd-5-1091-2012.
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Abstract. The influence of seasonal phenology on canopy photosynthesis in tropical evergreen forests remains poorly understood, and its representation in global ecosystem models is highly simplified, typically with no seasonal variation of canopy leaf properties taken into account. Including seasonal variation in leaf age and photosynthetic capacity could improve the correspondence of global vegetation model outputs with the wet–dry season CO2 patterns measured at flux tower sites in these forests. We introduced a leaf litterfall dynamics scheme in the global terrestrial ecosystem model ORCHIDEE based on seasonal variations in net primary production (NPP), resulting in higher leaf turnover in periods of high productivity. The modifications in the leaf litterfall scheme induce seasonal variation in leaf age distribution and photosynthetic capacity. We evaluated the results of the modification against seasonal patterns of three long-term in-situ leaf litterfall datasets of evergreen tropical forests in Panama, French Guiana and Brazil. In addition, we evaluated the impact of the model improvements on simulated latent heat (LE) and gross primary productivity (GPP) fluxes for the flux tower sites Guyaflux (French Guiana) and Tapajós (km 67, Brazil). The results show that the introduced seasonal leaf litterfall corresponds well with field inventory leaf litter data and times with its seasonality. Although the simulated litterfall improved substantially by the model modifications, the impact on the modelled fluxes remained limited. The seasonal pattern of GPP improved clearly for the Guyaflux site, but no significant improvement was obtained for the Tapajós site. The seasonal pattern of the modelled latent heat fluxes was hardly changed and remained consistent with the observed fluxes. We conclude that we introduced a realistic and generic litterfall dynamics scheme, but that other processes need to be improved in the model to achieve better simulations of GPP seasonal patterns for tropical evergreen forests.
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Adachi, Minaco, Atsushi Ishida, Sarayudh Bunyavejchewin, Toshinori Okuda, and Hiroshi Koizumi. "Spatial and temporal variation in soil respiration in a seasonally dry tropical forest, Thailand." Journal of Tropical Ecology 25, no. 5 (September 2009): 531–39. http://dx.doi.org/10.1017/s026646740999006x.
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Abstract:Spatial and seasonal variation in soil respiration rates were investigated in a tropical dry forest in Thailand. The spatial variation was examined at 50 points within a 2-ha plot in the forest floor during the dry and wet seasons. The seasonal and diurnal variations in soil respiration were measured at 16 and 5 points, respectively. The mean soil respiration rate during the wet season was 1041 ± 542 mg CO2 m−2 h−1 (mean ± SD), which is about twice that during the dry season. Soil respiration rate was negatively correlated with soil water content during the wet season. A polynomial equation using seasonal data describes soil respiration and water content: soil respiration rate increased with soil water content, but started to drop when soil water content exceeded 21%. The diurnal variation in soil respiration rate during the wet season was positively correlated with soil temperature, whereas during the wet season it was not correlated with soil temperature. The diurnal variation in soil respiration rate during the dry season showed a midday depression. The estimation of soil carbon flux with polynomial equations should incorporate different functions for the wet and dry seasons in tropical dry forests.
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Parsons, S. A., V. Valdez-Ramirez, R. A. Congdon, and S. E. Williams. "Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region." Biogeosciences 11, no. 18 (September 18, 2014): 5047–56. http://dx.doi.org/10.5194/bg-11-5047-2014.
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Abstract. The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp.: r2 = 0.63, n = 30; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall input was generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry season being more recalcitrant to decay.
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Parsons, S. A., V. Valdez-Ramirez, R. A. Congdon, and S. E. Williams. "Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region." Biogeosciences Discussions 11, no. 6 (June 3, 2014): 7901–29. http://dx.doi.org/10.5194/bgd-11-7901-2014.
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Abstract. The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability, using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp: r2 = 0.63, n = 30 plots; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall inputs were generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry being more recalcitrant to decay.
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Adachi, M., A. Ito, A. Ishida, W. R. Kadir, P. Ladpala, and Y. Yamagata. "Carbon budget of tropical forests in Southeast Asia and the effects of deforestation: an approach using a process-based model and field measurements." Biogeosciences 8, no. 9 (September 20, 2011): 2635–47. http://dx.doi.org/10.5194/bg-8-2635-2011.
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Abstract. More reliable estimates of the carbon (C) stock within forest ecosystems and C emission induced by deforestation are urgently needed to mitigate the effects of emissions on climate change. A process-based terrestrial biogeochemical model (VISIT) was applied to tropical primary forests of two types (a seasonal dry forest in Thailand and a rainforest in Malaysia) and one agro-forest (an oil palm plantation in Malaysia) to estimate the C budget of tropical ecosystems in Southeast Asia, including the impacts of land-use conversion. The observed aboveground biomass in the seasonal dry tropical forest in Thailand (226.3 t C ha−1) and the rainforest in Malaysia (201.5 t C ha−1) indicate that tropical forests of Southeast Asia are among the most C-abundant ecosystems in the world. The model simulation results in rainforests were consistent with field data, except for the NEP, however, the VISIT model tended to underestimate C budget and stock in the seasonal dry tropical forest. The gross primary production (GPP) based on field observations ranged from 32.0 to 39.6 t C ha−1 yr−1 in the two primary forests, whereas the model slightly underestimated GPP (26.5–34.5 t C ha−1 yr−1). The VISIT model appropriately captured the impacts of disturbances such as deforestation and land-use conversions on the C budget. Results of sensitivity analysis showed that the proportion of remaining residual debris was a key parameter determining the soil C budget after the deforestation event. According to the model simulation, the total C stock (total biomass and soil C) of the oil palm plantation was about 35% of the rainforest's C stock at 30 yr following initiation of the plantation. However, there were few field data of C budget and stock, especially in oil palm plantation. The C budget of each ecosystem must be evaluated over the long term using both the model simulations and observations to understand the effects of climate and land-use conversion on C budgets in tropical forest ecosystems.
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Rosa M., Sosa-Amay, Guillermo E. Delgado Paredes, Cecilia Vásquez Díaz, Zuñe-Da Silva Felipe, and Consuelo Rojas Idrogo. "IN VITRO PROPAGATION OF VACHELLIA MACRACANTHA, AN IMPORTANT SPECIES OF THE SEASONALLY DRY TROPICAL FOREST IN NORTHERN PERU." International Journal of Research -GRANTHAALAYAH 8, no. 11 (December 19, 2020): 371–80. http://dx.doi.org/10.29121/granthaalayah.v8.i11.2020.2502.
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Vachellia macracantha (ex Acacia macracantha) is one of the most important tree species in the Seasonally Dry Tropical Forest (SDTR) of northern Peru. The study aims to develop an efficient callus induction and micropropagation protocol from microcuttings of adult trees of this mentioned species, distributed across the North of Peru to the South of Ecuador. Shoot and uninodal microcuttings from three to five-year-old plants were investigated respecting their vegetative propagation and rooting capacity in vitro. High levels of NAA (2.5 to 7.5 mg L-1) were most efficient for shoot elongation and axillary bud development, although the basal callus formation and defolitation occurrence was also very high. In this case, the NAA 0.02 mg L-1, BAP 0.05, and GA3 0.05 mg L-1 interaction has been produced a better multiplication rate after 30 days without both basal callus formation and defoliation. Our findings suggest that other treatments tested such as NAA-BAP, NAA-KIN and NAA-2iP interaction, not were significantly satisfactory. Rooting response and consequently shoot elongation were always better with IBA (0.5 to 2.0 mg L-1) than NAA, under the same growth regulators concentrations.
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Haro-Carrión, Xavier, and Jane Southworth. "Understanding Land Cover Change in a Fragmented Forest Landscape in a Biodiversity Hotspot of Coastal Ecuador." Remote Sensing 10, no. 12 (December 7, 2018): 1980. http://dx.doi.org/10.3390/rs10121980.
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Understanding forest cover changes is especially important in highly threatened and understudied tropical dry forest landscapes. This research uses Landsat images and a Random Forest classifier (RF) to map old-growth, secondary, and plantation forests and to evaluate changes in their coverage in Ecuador. We used 46 Landsat-derived predictors from the dry and wet seasons to map these forest types and to evaluate the importance of having seasonal variables in classifications. Initial RF models grouped old-growth and secondary forest as a single class because of a lack of secondary forest training data. The model accuracy was improved slightly from 92.8% for the wet season and 94.6% for the dry season to 95% overall by including variables from both seasons. Derived land cover maps indicate that the remaining forest in the landscape occurs mostly along the coastline in a matrix of pastureland, with less than 10% of the landscape covered by plantation forests. To obtain secondary forest training data and evaluate changes in forest cover, we conducted a change analysis between the 1990 and 2015 images. The results indicated that half of the forests present in 1990 were cleared during the 25-year study period and highlighted areas of forest regrowth. We used these areas to extract secondary forest training data and then re-classified the landscape with secondary forest as a class. Classification accuracies decreased with more forest classes, but having data from both seasons resulted in higher accuracy (87.9%) compared to having data from only the wet (85.8%) or dry (82.9%) seasons. The produced cover maps classified the majority of previously identified forest areas as secondary, but these areas likely correspond to forest regrowth and to degraded forests that structurally resemble secondary forests. Among the few areas classified as old-growth forests are known reserves. This research provides evidence of the importance of using bi-seasonal Landsat data to classify forest types and contributes to understanding changes in forest cover of tropical dry forests.
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Koptur, Suzanne, William A. Haber, Gordon W. Frankie, and Herbert G. Baker. "Phenological studies of shrub and treelet species in tropical cloud forests of Costa Rica." Journal of Tropical Ecology 4, no. 4 (November 1988): 323–46. http://dx.doi.org/10.1017/s0266467400002984.
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ABSTRACT(1) During 1978–1981, marked individuals of 107 species of treelets and shrubs in three forest types between 1300–1650 m elevation at Monteverde, Costa Rica, were monitored at monthly intervals for behaviour of leafing, flowering, and fruiting.(2) Although there was not a pronounced seasonal pattern of leafing activity, more species produced new leaves in the dry season. Species that flush large quantities of new leaves do so more commonly in the drier months. Leaf loss was gradual and unobtrusive in species observed.(3) Flowering activity was greatest in the late dry season and early wet season. Most species exhibited extended flowering; only 15% of the species were massively flowering. Massive flowerers showed less seasonality than extended flowerers.(4) Of the species studied, the majority had relatively unspecialized flowers which were visited by a variety of insects; small bee-pollination was the next most common, followed by hummingbird, beetle, settling moth, sphingid, butterfly, large bee and fly pollination (the pollination system of 18 species was unknown). Hummingbird pollinated species showed little seasonality of flowering when compared with species exhibiting small moth, and beetle pollination syndromes, as well as those with unspecialized flowers.(5) The vast majority of species studied have fleshy fruits (sarcochores). Fruiting activity was less markedly seasonal than flowering. Species with fruit are more numerous in the second half of the year (the wet season and early dry season). The second year of the study saw substantially fewer species in fruit than the first year; this is attributed to the greater than usual rainfall and inclement weather during the peak flowering season.(6) Cloud forest shrub and treelet phenology is compared with patterns of other forests that have been studied. In general, the greater the rainfall, the less seasonality of flowering and fruiting is seen. Although Monteverde is very wet, rainfall is intermediate between that of lowland dry and lowland wet forest in Costa Rica. Seasonality of flowering and fruiting at Monteverde is more pronounced than at La Selva (wet) and less obvious than in Guanacaste (dry).
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PRADO, D. E. "SEASONALLY DRY FORESTS OF TROPICAL SOUTH AMERICA: FROM FORGOTTEN ECOSYSTEMS TO A NEW PHYTOGEOGRAPHIC UNIT." Edinburgh Journal of Botany 57, no. 3 (November 2000): 437–61. http://dx.doi.org/10.1017/s096042860000041x.
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The Pleistocenic Arc, which must have originated from the climatic shifts in South America during the late Pleistocene, ranges from the Caatingas of north-eastern Brazil through south-eastern Brazil to the Paraguay and Paraná rivers confluence, into south-western Bolivia and north-western Argentina, and extends sporadically into dry Andean valleys of Peru or coastal western Ecuador. It is regarded as a new phytogeographic unit for South America, here named the Tropical Seasonal Forests Region, as it is characterized by a considerable number of endemic plant taxa at both generic and species level. The paradigm of the arc is the distribution pattern of Anadenanthera colubrina (Fabaceae), which, when superimposed on those of other woody species of seasonal forests, permits a reasonably accurate mapping of the new region, which might also have biogeographic implications for endemic bird taxa. The plant communities of this newly recognized unit are unique in their nature and floristic composition, when compared with other floristic areas of the continent by means of classic phytosociological and numerical analyses (PCA). These ecosystems have remained submerged within other vegetation units in South American phytogeography (such as the Chaquenian or Amazonian regions), and have been particularly neglected in conservation policies. An urgent call is made for these areas to be preserved before they disappear, because they are located in areas with some of the best agricultural soils of tropical South America, and therefore subject to clearing for farming.
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Read, Larissa, and Deborah Lawrence. "Litter Nutrient Dynamics During Succession in Dry Tropical Forests of the Yucatan: Regional and Seasonal Effects." Ecosystems 6, no. 8 (December 1, 2003): 747–61. http://dx.doi.org/10.1007/s10021-003-0177-1.
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Ishida, A., S. Diloksumpun, P. Ladpala, D. Staporn, S. Panuthai, M. Gamo, K. Yazaki, M. Ishizuka, and L. Puangchit. "Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand." Tree Physiology 26, no. 5 (May 1, 2006): 643–56. http://dx.doi.org/10.1093/treephys/26.5.643.
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Mendes, Keila R., Suany Campos, Pedro R. Mutti, Rosaria R. Ferreira, Tarsila M. Ramos, Thiago V. Marques, Jean S. dos Reis, et al. "Assessment of SITE for CO2 and Energy Fluxes Simulations in a Seasonally Dry Tropical Forest (Caatinga Ecosystem)." Forests 12, no. 1 (January 15, 2021): 86. http://dx.doi.org/10.3390/f12010086.
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Although seasonally dry tropical forests are considered invaluable to a greater understanding of global carbon fluxes, they remain as one of the ecosystems with the fewest observations. In this context, ecological and ecosystem models can be used as alternative methods to answer questions related to the interactions between the biosphere and the atmosphere in dry forests. The objective of this study was to calibrate the simple tropical ecosystem model (SITE) and evaluate its performance in characterizing the annual and seasonal behavior of the energy and carbon fluxes in a preserved fragment of the Caatinga biome. The SITE model exhibited reasonable applicability to simulate variations in CO2 and energy fluxes (r > 0.7). Results showed that the calibrated set of vegetation parameters adequately simulated gross primary productivity (GPP) and net ecosystem CO2 exchange (NEE). The SITE model was also able to accurately retrieve the time at which daily GPP and NEE peaked. The model was able to simulate the partition of the available energy into sensible and latent heat fluxes and soil heat flux when the calibrated parameters were used. Therefore, changes in the dynamics of dry forests should be taken into consideration in the modeling of ecosystem carbon balances.
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Ahrestani, Farshid S., Ignas M. A. Heitkönig, and Herbert H. T. Prins. "Diet and habitat-niche relationships within an assemblage of large herbivores in a seasonal tropical forest." Journal of Tropical Ecology 28, no. 4 (June 1, 2012): 385–94. http://dx.doi.org/10.1017/s0266467412000302.
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Abstract:There is little understanding of how large mammalian herbivores in Asia partition habitat and forage resources, and vary their diet and habitat selection seasonally in order to coexist. We studied an assemblage of four large herbivores, chital (Axis axis), sambar (Cervus unicolor), gaur (Bos gaurus) and Asian elephant (Elephas maximus), in the seasonal tropical forests of Bandipur and Mudumalai, South India, and tested predictions regarding the species’ seasonal diet browse : graze ratios, habitat selection and habitat-niche preference and overlap. Field data collected for the study included the seasonal variation in grass quality, the seasonal variation in δ13C in the species’ faeces and the seasonal variation in the species’ habitat selection and overlap using a grid-based survey. Results of the δ13C analyses showed that the chital was more of a grazer in the wet season (−17.9‰ to −21.6‰), but that it increased the proportion of browse in its diet in the dry season (−25.6‰ to −27.7‰); the gaur was a grazer for most of the year (−15.3‰ to −18.6‰); the sambar preferred to browse throughout the year (−21.1‰ to −30.4‰); and that the elephant was a mixed feeder (−14.2‰ to −21.4‰). Elephant habitat-niche breadth was high (0.53 in wet and 0.54 in dry) and overlapped equally with that of the other species in both seasons (0.39–0.94). The gaur had the most restricted habitat-niche breadth in both seasons (0.25 in wet and 0.28 in dry), and it switched from the moist deciduous habitat in the dry season to the dry deciduous habitat in the wet season. These results offer the first insights into the seasonal variation in browse : graze diet ratios and the habitat-niche overlap amongst the common largest-bodied mammalian herbivore species found in South India.
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Poorter, Lourens, and Yáskara Hayashida-Oliver. "Effects of seasonal drought on gap and understorey seedlings in a Bolivian moist forest." Journal of Tropical Ecology 16, no. 4 (July 2000): 481–98. http://dx.doi.org/10.1017/s026646740000153x.
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In tropical moist forests, length of the dry period may have a profound influence on leaf dynamics, plant growth and survival. To evaluate the role of light and water availability on seedling performance, a 1-y experiment was carried out in a tropical moist forest in the Bolivian Amazon in which seedlings of three tree species (Brosimum lactescens, Cedrela odorata and Schizolobium amazonicum) were planted in gaps and the understorey. Variation in length of the dry period was simulated by subjecting part of the seedlings to a water treatment at the end of the dry period. Gaps and understorey had a similar soil moisture content, which varied between 39% in the wet season and 16% in the dry season. Height and leaf growth rates were higher in gap compared to understorey plants, and in the wet compared to the dry season. A high growth during the wet season provided gap plants with a decisive size advantage over understorey plants during the dry season. Their larger root system allowed gap plants to explore a larger surface area and deeper soil layers for water. Consequently, gap plants of Cedrela experienced a shorter deciduous period (22 d) compared to understorey plants (61 d). Watering at the end of the dry season cued the flushing of new leaves by Cedrela, although it did not lead to a higher plant growth.
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Albuquerque, Ulysses Paulino de, Laise de Holanda Cavalcanti Andrade, and Ana Carolina Oliveira de Silva. "Use of plant resources in a seasonal dry forest (Northeastern Brazil)." Acta Botanica Brasilica 19, no. 1 (March 2005): 27–38. http://dx.doi.org/10.1590/s0102-33062005000100004.
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To study the use of plant resources by a rural community in a seasonal dry forest, plots were established in a disturbed area and in a relatively preserved area. The study was carried out in caatinga vegetation located at the municipality of Alagoinha (08º27'59" S and 36º46'33" W), state of Pernambuco, Northeastern Brazil. The results show a pattern of medicinal resources offering similar to that found in other tropical forests, in which the disturbed areas or those of secondary vegetation are a major source of medicinal plants. Nevertheless, a new pattern was evidenced as it was found that disturbed areas are not preferred by local people, and that it may be related to temporal availability of resources (adaptation to the characteristic seasonality of the vegetation type) and to the permanence of cultural values and basic knowledge on plants of the natural vegetation, which are of major importance for the community.
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VAZ-SILVA, WILIAN, PAULA HANNA VALDUJO, and JOSÉ P. POMBAL JR. "New species of the Rhinella crucifer group (Anura, Bufonidae) from the Brazilian Cerrado." Zootaxa 3265, no. 1 (April 10, 2012): 57. http://dx.doi.org/10.11646/zootaxa.3265.1.4.
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A new species of Rhinella of Central Brazil from the Rhinella crucifer group is described. Rhinella inopina sp. nov. is restricted to the disjunct Seasonal Tropical Dry Forests enclaves in the western Cerrado biome. The new species is characterized mainly by head wider than long, shape of parotoid gland, and oblique arrangement of the parotoid gland. Data on natural history and distribution are also presented.
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Stan, Kayla, and Arturo Sanchez-Azofeifa. "Tropical Dry Forest Diversity, Climatic Response, and Resilience in a Changing Climate." Forests 10, no. 5 (May 23, 2019): 443. http://dx.doi.org/10.3390/f10050443.
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Central and South America tropical dry forest (TDF) is a water-limited biome with a high number of endemic species and numerous ecosystem services which has experienced a boom in research in the last decade. Although the number of case studies across these seasonal, water-limited, tropical forests has increased, there has not been a comprehensive review to assess the physiological variability of this biome across the continent and assess how these forests respond to climatic variables. Additionally, understanding forest change and resilience under climatic variability, currently and in the future, is essential for assessing the future extent and health of forests in the future. Therefore, the objective of this paper is to provide a literature review on the variability of TDF diversity and structure across a latitudinal gradient and to assess how these components respond to differences in climatic variables across this geographic area. We first assess the current state of understanding of the structure, biomass, phenological cycles, and successional stages across the latitudinal gradient. We subsequently review the response of these five areas to differences in precipitation, temperature, and extreme weather events, such as droughts and hurricanes. We find that there is a range of adaptability to precipitation, with many areas exhibiting drought tolerance except under the most extreme circumstances, while being susceptible to damage from increased extreme precipitation events. Finally, we use this climatic response to provide a commentary on the projected resilience of TDFs under climatic changes, finding a likelihood of resilience under drying scenarios, although model projections do not agree on the magnitude or direction of precipitation change. This review of quantitative studies will provide more concrete details on the current diversity that encompasses the TDF, the natural climatic ranges under which this ecosystem can survive and thrive, and can help inform future forest management practices under climate change scenarios.
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Martin, K. C., and W. J. Freeland. "Herpetofauna of a northern Australian monsoon rain forest: seasonal changes and relationships to adjacent habitats." Journal of Tropical Ecology 4, no. 3 (August 1988): 227–38. http://dx.doi.org/10.1017/s0266467400002790.
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ABSTRACTThe herpetofauna of a floodplain monsoon rain forest in northern Australia is composed primarily of species from non rain forest habitats. The majority of frog species use rain forest as a seasonal refuge, and there is a marked increase in numbers during the dry season. Faunal richness lies within limits expected on the basis of the length of the dry season and species richnesses of non-Australian faunas. There are few lizard species and an abundance of frog species (none of which is a rain forest specialist) in comparison to rain forest herpetofaunas in other tropical regions. The impoverished lizard fauna, and the paucity of rain forest specialists may be because (a) seasonal invasion of rain forest by frogs prevents evolution of, or colonization by, specialists or (b) rain forest specialists may not have been able to cross semiarid habitats separating the Northern Territory from eastern Australian rain forests. The herpetofaunas of monsoon forests in Cape York Peninsula may provide a means of distinguishing between these hypotheses.
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O'Driscoll Worman, Cedric, and Colin A. Chapman. "Seasonal variation in the quality of a tropical ripe fruit and the response of three frugivores." Journal of Tropical Ecology 21, no. 6 (October 19, 2005): 689–97. http://dx.doi.org/10.1017/s0266467405002725.
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Seasonality in tropical forests can be more subtle than that of temperate forests but still affects the resources available to wildlife. Much work has been done describing changes in fruit availability and dietary composition but the nutritional quality of any particular food item is assumed to be relatively constant. We investigated seasonal changes in the quality of the ripe fruit of Celtis durandii, a common tree that produces fruit year-round and is important in the diets of many species. The lipid content of the ripe fruit was found to be highly variable (0.3–30.8% dry matter) among months and this variation was positively correlated with the summed daily rainfalls of the previous and concurrent months. The amount of this fruit in the diets of three frugivorous primate species (Cercopithecus mitis, Cercopithecus ascanius and Lophocebus albigena) was positively related to measured or estimated lipid levels in the fruit. Such predictable changes in the quality of a constantly available fruit have not been previously reported and suggest that the resources provided by tropical forests may be more seasonal than shown by common measures of fruit availability.
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Rifai, Sami W., Cécile A. J. Girardin, Erika Berenguer, Jhon del Aguila-Pasquel, Cecilia A. L. Dahlsjö, Christopher E. Doughty, Kathryn J. Jeffery, et al. "ENSO Drives interannual variation of forest woody growth across the tropics." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1760 (October 8, 2018): 20170410. http://dx.doi.org/10.1098/rstb.2017.0410.
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Meteorological extreme events such as El Niño events are expected to affect tropical forest net primary production (NPP) and woody growth, but there has been no large-scale empirical validation of this expectation. We collected a large high–temporal resolution dataset (for 1–13 years depending upon location) of more than 172 000 stem growth measurements using dendrometer bands from across 14 regions spanning Amazonia, Africa and Borneo in order to test how much month-to-month variation in stand-level woody growth of adult tree stems (NPP stem ) can be explained by seasonal variation and interannual meteorological anomalies. A key finding is that woody growth responds differently to meteorological variation between tropical forests with a dry season (where monthly rainfall is less than 100 mm), and aseasonal wet forests lacking a consistent dry season. In seasonal tropical forests, a high degree of variation in woody growth can be predicted from seasonal variation in temperature, vapour pressure deficit, in addition to anomalies of soil water deficit and shortwave radiation. The variation of aseasonal wet forest woody growth is best predicted by the anomalies of vapour pressure deficit, water deficit and shortwave radiation. In total, we predict the total live woody production of the global tropical forest biome to be 2.16 Pg C yr −1 , with an interannual range 1.96–2.26 Pg C yr −1 between 1996–2016, and with the sharpest declines during the strong El Niño events of 1997/8 and 2015/6. There is high geographical variation in hotspots of El Niño–associated impacts, with weak impacts in Africa, and strongly negative impacts in parts of Southeast Asia and extensive regions across central and eastern Amazonia. Overall, there is high correlation ( r = −0.75) between the annual anomaly of tropical forest woody growth and the annual mean of the El Niño 3.4 index, driven mainly by strong correlations with anomalies of soil water deficit, vapour pressure deficit and shortwave radiation. This article is part of the discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.