scholarly journals Spatial Estimation of the Latent Heat Flux in a Tropical Dry Forest by Using Unmanned Aerial Vehicles

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 604 ◽  
Author(s):  
Philip Marzahn ◽  
Linda Flade ◽  
Arturo Sanchez-Azofeifa
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Dry Forests ◽  
Flux Tower ◽  
Spatially Distributed ◽  
Triangle Method

In this paper, we address the retrieval of spatially distributed latent heat flux ( λ E) over a tropical dry forest using multi-spectral and thermal unmanned aerial vehicle (UAV) imagery. The study was carried out in the Santa Rosa National Park Environmental Monitoring Super-Site, Costa Rica, in June 2016. The triangle method was used to derive λ E from the UAV imagery and the results were compared to λ E measurements of an eddy covariance system within the coincident eddy flux tower footprint. The tower footprint was derived using a two-dimensional parameterization model for flux footprint prediction. The comparisons with the flux tower measurements showed a mean relative difference of 10.98% with a slight overestimation of the UAV-based flux retrievals by nearly 7.7 Wm − 2 . The results are in good agreement with satellite-based retrievals, as provided by the literature, for which the triangle method was initially developed and mostly used so far. This study proved to be a promising approach for transferring the triangle method to UAV imagery in ecosystems such as tropical dry forests. With the presented approach, new details in spatially distributed latent heat flux estimates at ultra-high resolution are now possible, thereby potentially closing the gap in spatial resolution between satellites and flux towers. Even more, it allows tracing the latent heat flux from single trees at leaf level. Besides, this approach also opens new perspectives for the monitoring of latent heat fluxes in tropical dry forests.

scholarly journals GERMINATION OF STORED SEEDS OF FOUR TREE SPECIES FROM THE TROPICAL DRY FOREST OF MORELOS, MEXICO

2014 ◽  
Vol 92 (2) ◽  
pp. 281 ◽  
Author(s):  
Martha Cervantes ◽  
Eliane Ceccon ◽  
Consuelo Bonfil
Keyword(s):  
Seed Germination ◽  
Seed Size ◽  
Storage Time ◽  
Germination Rate ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Germination Capacity ◽  
Dry Forests ◽  
And Storage

<p><span style="font-size: medium;"><span style="font-family: Times New Roman;">Studies on propagation of trees of Tropical Dry Forests are scarce in Mexico, besides, the provenance of seeds used in reforestation programs is generally unknown or poorly addressed. Knowledge on seed germination patterns of different provenances, and how they change through time, is useful to identify adequate sources of seeds and to develop seed collection and storage programs under the low-tech conditions prevailing in most rural nurseries. We evaluated seed size variation and germination of stored seeds from three different provenances per species in <em>Acacia bilimekii</em>, <em>Haematoxylum brasiletto</em>, <em>Lysiloma acapulcense</em>, and<em> L. divaricatum</em>.<em> </em>Seeds were collected in four sites in the Tropical Dry Forest of Morelos, Mexico, and were stored at room temperature; seed size was estimated through the volume of 75 seeds per provenance/species. Seed germination tests were made periodically from six to 24 months after storage and the effects of provenance and storage time on germination were analyzed using Anovas. There were significant differences in seed size among provenances in all species, while the effect of provenance on germination rate was significant in three of them. Germination rate changed with storage time among species and provenances. After 24 months, germination capacity was still ≥ 50% in all provenances of the two <em>Lysiloma</em> species, but in <em>A.</em> <em>bilimekii</em> there were large differences among provenances. Mean germination capacity was low in <em>H. brasiletto</em> after six months. More research on seed germination and storage of a larger set of species and provenances is needed to restore the Mexican tropical dry forests. </span></span></p>

scholarly journals Lepidoptera are Relevant Bioindicators of Passive Regeneration in Tropical Dry Forests

Diversity ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 231 ◽  
Author(s):  
Luc Legal ◽  
Marine Valet ◽  
Oscar Dorado ◽  
Jose Maria de Jesus-Almonte ◽  
Karime López ◽  
...  
Keyword(s):  
Anthropogenic Disturbance ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Primary Forest ◽  
Dry Forests ◽  
Study Zone ◽  
Butterfly Communities ◽  
Passive Regeneration ◽  
Different Levels

Most evaluations of passive regeneration/natural succession or restoration have dealt with tropical rain forest or temperate ecosystems. Very few studies have examined the regeneration of tropical dry forests (TDF), one of the most damaged ecosystem types in the world. Owing to their species diversity and abundance, insects have been widely used as bioindicators of restoration. Butterflies were among the most abundant and useful groups. We sampled four sites with different levels of anthropogenic disturbance in a Mexican TDF (Morelos State) and compared butterfly communities. A first goal was to examine whether adult butterflies were significant bioindicators owing to their specificity to restricted habitats. A second aim was to determine if differences exist in butterfly communities between some fields abandoned from 4–8, 8–15 and 15–30 years and a reference zone considered as primary forest. We found 40% to 50% of the species of butterflies were specifically related to a habitat and/or a level of anthropogenic disturbance. The time it takes for passive regeneration and recovery of the Mexican tropical dry forest is much higher than 25 years (our older zone), considering that almost none of the butterflies found in our conserved reference zone were present in our 25 year aged study zone.

Tree community change in a tropical dry forest: the role of roads and exotic plant invasion

2009 ◽  
Vol 36 (3) ◽  
pp. 201-207 ◽  
Author(s):  
AYESHA E. PRASAD
Keyword(s):  
Tropical Dry Forest ◽  
Community Change ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Exotic Plant ◽  
Dry Forests ◽  
Exotic Plant Invasion ◽  
Tree Community ◽  
Tree Communities ◽  
Road Width

SUMMARYAmong the most endangered tropical ecosystems, tropical dry forests are threatened by degradation that includes edge effects arising from perturbations such as the creation and maintenance of roads and other clearings. While much is known about these adverse effects on tree communities in tropical moist forests, similar effects in tropical dry forests are little understood. This paper examines the relationship between roads, road-related exotic plant invasion and tree community change in a tropical dry forest in southern India. Forty pairs of roadside and interior plots across four factorial combinations of road width (wide and narrow) and understorey type (native and exotic) were sampled. Tree death and extant tree community composition were compared using generalized linear models and similarity analyses. Tree death near roads was more than double that away from them, suggesting that roads may increase tree death in these forests. The interactive effect of understorey type (exotic or native) and road width on tree death was significant, with highest tree death near wide roads bordered by exotic understorey. Conversely, tree community composition was influenced by road width and understorey type, but not by proximity to roads. Creation and maintenance of roads for forest management may have serious implications for tree communities in tropical dry forests and should thus be minimized. Exotic plants may also be important contributors to increasing tree death, and further research on their impacts, particularly into underlying mechanisms, is critical to the long-term conservation of tropical dry forest communities.

An Overview of the Role of Plant Functional Traits in Tropical Dry Forests

2020 ◽  
pp. 89-113
Author(s):  
Abhinav Yadav ◽  
Pramit Verma ◽  
Akhilesh Singh Raghubanshi
Keyword(s):  
Forest Restoration ◽  
Rainfall Variability ◽  
Tropical Dry Forest ◽  
Functional Trait ◽  
Research Field ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Dry Forests ◽  
Interannual Rainfall Variability ◽  
Restoration Practice

Tropical dry forests (TDFs) are characterized by pronounced seasonality in precipitation, with several months of prolonged drought, 80% of annual precipitation occurring during a four- to six-month rainy season, and high interannual rainfall variability. Surprisingly, there are relatively few studies addressing patterns of functional trait in tropical dry forest (TDF) ecosystems. Functional trait analysis across plant species and the environment is a rapidly developing research field with many possible applications for forest restoration practice. Trait-based ecological research within TDFs will advance our understanding of how these ecosystems interact with and differ from other tropical ecosystems.

scholarly journals Long-term impacts of mid-Holocene drier climatic conditions on Bolivian tropical dry forests

2019 ◽  
Vol 93 ◽  
pp. 204-224 ◽  
Author(s):  
Heather J. Plumpton ◽  
Francis E. Mayle ◽  
Bronwen S. Whitney
Keyword(s):  
Climate Models ◽  
Fire Regime ◽  
Tropical Dry Forest ◽  
Climatic Conditions ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Dry Forests ◽  
Seasonally Dry ◽  
Threat Status

AbstractThe Bolivian Chiquitano dry forest is the largest block of intact seasonally dry tropical forest in South America and is a priority ecoregion for conservation due to its high threat status. However, the long-term impacts of drier climatic conditions on tropical dry forests are not well understood, despite climate models predicting increased droughts over Bolivia in the coming century. In this paper, we assess the impacts of drier climatic conditions during the mid-Holocene on the Bolivian Chiquitano tropical dry forest using fossilised pollen, phytoliths, macro-charcoal, and geochemical proxies from a sediment core from a large lake (Laguna Mandioré) on the Bolivia–Brazil border. Our results show that drier climatic conditions during the mid-Holocene caused a local-scale, ecotonal expansion of upland savannah at the expense of dry forest. Interaction between drier climatic conditions and fire regime likely exerted a stronger control over the position of the dry forest–savannah ecotone than edaphic factors. However, the majority of the dry forest within the lake catchment maintained a closed canopy throughout the drier conditions of the mid-Holocene, despite floristic turnover towards more drought-tolerant taxa. These findings imply overall resilience of the Chiquitano dry forest biome to future drought, albeit with floristic changes and upland savannah encroachment at ecotones.

Life history characteristics and rarity of woody plants in tropical dry forest fragments of Central America

1999 ◽  
Vol 15 (5) ◽  
pp. 637-649 ◽  
Author(s):  
Thomas W. Gillespie
Keyword(s):  
Life History ◽  
Central America ◽  
Tropical Dry Forest ◽  
Dry Forest ◽  
Tropical Dry Forests ◽  
Similar Proportion ◽  
Forest Fragments ◽  
Dry Forests ◽  
Dioecious Species ◽  
Life History Characteristics

Breeding systems and dispersal mechanisms of plants (≥ 2.5 cm dbh) were examined in fragments of tropical dry forest in Central America to identify life-history characteristics associated with rarity. In particular, the richness and abundance of dioecious and mammal-dispersed trees and shrubs were examined to identify potential associations with precipitation, anthropogenic disturbance, and area. Plots totalling 1000 m2 per site were established in seven nature reserves in Costa Rica (two sites) and Nicaragua (five sites). Overall, tropical dry forests of Central America have a similar proportion of dioecious species to other lowland neotropical forests and a similar proportion of wind-dispersed plants to other tropical dry forests around the world. However, the number of dioecious and mammal-dispersed species declined with decreasing forest cover within each reserve. Although dioecious species were rare in smaller forest fragments, some of these species will not be threatened with regional extinction because they are early successional plants, they have large geographic ranges, and they are not restricted to the tropical dry forest life zone. Mammal-dispersed plants were rare in small fragments, but it is not clear whether this was due to the loss of dispersal vectors or other life-history characteristics.

Correcting for systematic error in satellite-derived latent heat flux due to assumptions in temporal scaling: Assessment from flux tower observations

2011 ◽  
Vol 409 (1-2) ◽  
pp. 140-148 ◽  
Author(s):  
Thomas G. Van Niel ◽  
Tim R. McVicar ◽  
Michael L. Roderick ◽  
Albert I.J.M. van Dijk ◽  
Luigi J. Renzullo ◽  
...  
Keyword(s):  
Heat Flux ◽  
Systematic Error ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Temporal Scaling ◽  
Flux Tower

An analog period method for gap‐filling of latent heat flux measurements

2021 ◽  
Author(s):  
Lucas Emilio B. Hoeltgebaum ◽  
Nelson Luís Dias ◽  
Marcelo Azevedo Costa
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Gap Filling ◽  
Flux Measurements
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