scholarly journals Characterization of Dry-Season Phenology in Tropical Forests by Reconstructing Cloud-Free Landsat Time Series

2021 ◽  
Vol 13 (23) ◽  
pp. 4736
Author(s):  
Xiaolin Zhu ◽  
Eileen H. Helmer ◽  
David Gwenzi ◽  
Melissa Collin ◽  
Sean Fleming ◽  
...  
Keyword(s):  
Time Series ◽  
Puerto Rico ◽  
Tropical Forests ◽  
Tropical Dry Forest ◽  
Dry Season ◽  
Dry Forest ◽  
High Quality ◽  
Forest Zone ◽  
Fine Resolution ◽  
Field Plots

Fine-resolution satellite imagery is needed for characterizing dry-season phenology in tropical forests since many tropical forests are very spatially heterogeneous due to their diverse species and environmental background. However, fine-resolution satellite imagery, such as Landsat, has a 16-day revisit cycle that makes it hard to obtain a high-quality vegetation index time series due to persistent clouds in tropical regions. To solve this challenge, this study explored the feasibility of employing a series of advanced technologies for reconstructing a high-quality Landsat time series from 2005 to 2009 for detecting dry-season phenology in tropical forests; Puerto Rico was selected as a testbed. We combined bidirectional reflectance distribution function (BRDF) correction, cloud and shadow screening, and contaminated pixel interpolation to process the raw Landsat time series and developed a thresholding method to extract 15 phenology metrics. The cloud-masked and gap-filled reconstructed images were tested with simulated clouds. In addition, the derived phenology metrics for grassland and forest in the tropical dry forest zone of Puerto Rico were evaluated with ground observations from PhenoCam data and field plots. Results show that clouds and cloud shadows are more accurately detected than the Landsat cloud quality assessment (QA) band, and that data gaps resulting from those clouds and shadows can be accurately reconstructed (R2 = 0.89). In the tropical dry forest zone, the detected phenology dates (such as greenup, browndown, and dry-season length) generally agree with the PhenoCam observations (R2 = 0.69), and Landsat-based phenology is better than MODIS-based phenology for modeling aboveground biomass and leaf area index collected in field plots (plot size is roughly equivalent to a 3 × 3 Landsat pixels). This study suggests that the Landsat time series can be used to characterize the dry-season phenology of tropical forests after careful processing, which will help to improve our understanding of vegetation–climate interactions at fine scales in tropical forests.

scholarly journals Madrigueras de Liomys pictus en dos selvas tropicales del Pacífico mexicano.

2009 ◽  
Vol 13 (1) ◽  
pp. 63 ◽  
Author(s):  
Yolanda Domínguez-Castellanos ◽  
Beatriz Hernandez Meza ◽  
Angeles Mendoza D. ◽  
Gerardo Ceballos González
Keyword(s):  
Seed Production ◽  
Tropical Forests ◽  
Plant Species ◽  
Deciduous Forest ◽  
Vegetation Type ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Mexican Pacific ◽  
La Selva

Resumen: Se determinó la estructura y el contenido de las madrigueras de Liomys pictus por tipo de vegetación y temporada del año, en dos selvas tropicales del Pacífico Mexicano. Se encontraron 24 madrigueras: en la selva baja la mayoría son complejas, mientras que  en la selva mediana son lineales, por consiguiente y de acuerdo a la clasificación de las madrigueras, en selva baja se presentaron madrigueras múltiples y en selva mediana madrigueras simples. De acuerdo al contenido, las de selva baja tienen en promedio una mayor cantidad de materiales en comparación a las de selva mediana. Se catalogaron un total de 248 especies de plantas de estas 50 se comparten en ambos sitios, del total de las especies se llegaron a identificar sólo 77. Las familias más representativas fueron Leguminoseae, Euphorbiaceae y Convolvulaceae. La estructura de las madrigueras no esta determinada por la temporalidad, sin embargo el contenido esta determinado con la cantidad de material almacenado aunque la producción de semillas esta definido por el patrón de fructificación que esta dado a lo largo del año.Palabras clave: Madrigueras, estructura, contenido, Liomys pictus, Jalisco, México.Abstract: We determined the structure and contents of burrows of Liomys pictus by vegetation type and season in two tropical forests of the Mexican Pacific. 24 burrows were found in the tropical dry forest and most complex, in the semi deciduous forest is linear, and therefore according to the classification of the burrows in the tropical dry forest are more numerous and simple in the semi deciduous forest. According to the content, of the tropical dry forest have on average a greater amount of material compared to the semi deciduous forest. Were categorized a total of 248 plant species of these 50 sites are shared in both the total number of species is to determine 77. The most representative families were Leguminoseae, Euphorbiaceae and Convulvolaceae. The structure of the burrows is not affected by the timing, but the content is determined with the amount of stored material but seed production is defined by the pattern of fruit that is given throughout the year.Key words: Burrows, structure, food hoarding, Liomys pictus, Jalisco, Mexico.

scholarly journals Tropical Dry Forest Resilience to Fire Depends on Fire Frequency and Climate

2021 ◽  
Vol 4 ◽  
Author(s):  
Maximilian Hartung ◽  
Geovana Carreño-Rocabado ◽  
Marielos Peña-Claros ◽  
Masha T. van der Sande
Keyword(s):  
Tropical Forests ◽  
Tropical Dry Forest ◽  
Remote Sensing Data ◽  
Fire Frequency ◽  
Dry Forest ◽  
Fire Disturbance ◽  
Fire Intensity ◽  
Forest Resilience ◽  
Landsat Satellite ◽  
In Fire

Wildfires are becoming increasingly frequent and devastating in many tropical forests. Although seasonally dry tropical forests (SDTF) are among the most fire-threatened ecosystems, their long-term response to frequent wildfires remains largely unknown. This study is among the first to investigate the resilience in response to fire of the Chiquitano SDTF in Bolivia, a large ecoregion that has seen an unprecedented increase in fire intensity and frequency in recent years. We used remote sensing data to assess at a large regional and temporal scale (two decades) how fire frequency and environmental factors determine the resilience of the vegetation to fire disturbance. Resilience was measured as the resistance to fire damage and post-fire recovery. Both parameters were monitored for forested areas that burned once (F1), twice (F2), and three times (F3) between 2000 and 2010 and compared to unburned forests. Resistance and recovery were analyzed using time series of the Normalized Burn Ratio (NBR) index derived from Landsat satellite imagery, and climatic, topographic, and a human development-related variable used to evaluate their influence on resilience. The overall resilience was lowest in forests that burned twice and was higher in forests that burned three times, indicating a possible transition state in fire resilience, probably because forests become increasingly adapted during recurrent fires. Climatic variables, particularly rainfall, were most influential in determining resilience. Our results indicate that the Chiquitano dry forest is relatively resilient to recurring fires, has the capacity to recover and adapt, and that climatic differences are the main determinants of the spatial variation observed in resilience. Nevertheless, further research is needed to understand the effect of the higher frequency and intensity of fires expected in the future due to climate change and land use change, which may pose a greater threat to forest resilience.

Distribution of the community of frugivorous birds along a successional gradient in a tropical dry forest in south-western Mexico

2014 ◽  
Vol 31 (1) ◽  
pp. 57-68 ◽  
Author(s):  
R. Carlos Almazán-Núñez ◽  
María del Coro Arizmendi ◽  
Luis E. Eguiarte ◽  
Pablo Corcuera
Keyword(s):  
Tropical Dry Forest ◽  
Dry Season ◽  
Dry Forest ◽  
Forest Fragments ◽  
Dry Forests ◽  
Bird Abundance ◽  
Frugivorous Birds ◽  
Seed Predators ◽  
Western Mexico ◽  
Successional Forests

Abstract:Few reports have described the relationship between the distribution of frugivorous birds and vegetation successional changes in dry forests. We assessed the abundance and behaviour of frugivorous birds in early, intermediate and mature dry forests in the Balsas river basin, Guerrero, Mexico. We selected nine dry-forest fragments, three fragments per stage, in these three stages of succession. We analysed the vegetation, estimated bird abundances in 10-min count periods, and recorded the way birds process fruits in circular plots (11–15 plots per fragment, 123 plots in total). Birds were classified as seed predators (15% of all individuals in this study), pulp consumers (15%) or legitimate dispersers (70%). Bird abundance was higher in mature forests in the dry season, while abundance and richness of legitimate dispersers and seed predators were positively related to vegetation complexity. Mature forests have a high vegetation complexity and a high cover ofBurseraspecies that produce fruit during the dry season. During the rains, abundance was higher in early-successional sites when the zoochorous plants produced fruit. Legitimate disperser migrants (i.e.Tyrannus vociferans, Myiarchus cinerascensandM. tyrannulus) were widespread, helping the establishment of zoochorous trees such asBurseraspp. in early-successional forests.

Spider monkeys use high-quality core areas in a tropical dry forest

2012 ◽  
Vol 287 (4) ◽  
pp. 250-258 ◽  
Author(s):  
N. Asensio ◽  
D. Lusseau ◽  
C. M. Schaffner ◽  
F. Aureli
Keyword(s):  
Tropical Dry Forest ◽  
Dry Forest ◽  
Spider Monkeys ◽  
High Quality ◽  
Core Areas

scholarly journals Seasonal and successional dynamics of size-dependent plant demographic rates in a tropical dry forest

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9636
Author(s):  
Irving Saenz-Pedroza ◽  
Richard Feldman ◽  
Casandra Reyes-García ◽  
Jorge A. Meave ◽  
Luz Maria Calvo-Irabien ◽  
...  
Keyword(s):  
Climate Change ◽  
Tropical Forests ◽  
Dry Season ◽  
Dry Forest ◽  
Species Density ◽  
Wet Season ◽  
Successional Stage ◽  
Size Dependent ◽  
Demographic Rates ◽  
Successional Stages

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.

scholarly journals Effect of fragmentation on the Costa Rican dry forest avifauna

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2422 ◽  
Author(s):  
Gilbert Barrantes ◽  
Diego Ocampo ◽  
José D. Ramírez-Fernández ◽  
Eric J. Fuchs
Keyword(s):  
Tropical Dry Forest ◽  
Bird Community ◽  
Dry Season ◽  
Costa Rican ◽  
Dry Forest ◽  
Forest Fragment ◽  
Avian Community ◽  
Forest Patches ◽  
Species Occupancy ◽  
Avian Assemblages

Deforestation and changes in land use have reduced the tropical dry forest to isolated forest patches in northwestern Costa Rica. We examined the effect of patch area and length of the dry season on nestedness of the entire avian community, forest fragment assemblages, and species occupancy across fragments for the entire native avifauna, and for a subset of forest dependent species. Species richness was independent of both fragment area and distance between fragments. Similarity in bird community composition between patches was related to habitat structure; fragments with similar forest structure have more similar avian assemblages. Size of forest patches influenced nestedness of the bird community and species occupancy, but not nestedness of assemblages across patches in northwestern Costa Rican avifauna. Forest dependent species (species that require large tracts of mature forest) and assemblages of these species were nested within patches ordered by a gradient of seasonality, and only occupancy of species was nested by area of patches. Thus, forest patches with a shorter dry season include more forest dependent species.

Mapping tropical dry forest height, foliage height profiles and disturbance type and age with a time series of cloud-cleared Landsat and ALI image mosaics to characterize avian habitat

2010 ◽  
Vol 114 (11) ◽  
pp. 2457-2473 ◽  
Author(s):  
E.H. Helmer ◽  
Thomas S. Ruzycki ◽  
Joseph M. Wunderle ◽  
Shannon Vogesser ◽  
Bonnie Ruefenacht ◽  
...  
Keyword(s):  
Time Series ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Forest Height

Unmixing Analysis of a Time Series of Hyperion Images Over the Guánica Dry Forest in Puerto Rico

2013 ◽  
Vol 6 (2) ◽  
pp. 329-338 ◽  
Author(s):  
Miguel A. Goenaga ◽  
Maria C. Torres-Madronero ◽  
Miguel Velez-Reyes ◽  
Skip J. Van Bloem ◽  
Jesus D. Chinea
Keyword(s):  
Time Series ◽  
Puerto Rico ◽  
Dry Forest
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