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1
Scholl, Martha A., Maoya Bassiouni e Angel J. Torres-Sánchez. "Drought stress and hurricane defoliation influence mountain clouds and moisture recycling in a tropical forest". Proceedings of the National Academy of Sciences 118, n. 7 (9 febbraio 2021): e2021646118. http://dx.doi.org/10.1073/pnas.2021646118.
Testo completoAbstract (sommario):
Mountain ranges generate clouds, precipitation, and perennial streamflow for water supplies, but the role of forest cover in mountain hydrometeorology and cloud formation is not well understood. In the Luquillo Experimental Forest of Puerto Rico, mountains are immersed in clouds nightly, providing a steady precipitation source to support the tropical forest ecosystems and human uses. A severe drought in 2015 and the removal of forest canopy (defoliation) by Hurricane Maria in 2017 created natural experiments to examine interactions between the living forest and hydroclimatic processes. These unprecedented land-based observations over 4.5 y revealed that the orographic cloud system was highly responsive to local land-surface moisture and energy balances moderated by the forest. Cloud layer thickness and immersion frequency on the mountain slope correlated with antecedent rainfall, linking recycled terrestrial moisture to the formation of mountain clouds; and cloud-base altitude rose during drought stress and posthurricane defoliation. Changes in diurnal cycles of temperature and vapor-pressure deficit and an increase in sensible versus latent heat flux quantified local meteorological response to forest disturbances. Temperature and water vapor anomalies along the mountain slope persisted for at least 12 mo posthurricane, showing that understory recovery did not replace intact forest canopy function. In many similar settings around the world, prolonged drought, increasing temperatures, and deforestation could affect orographic cloud precipitation and the humans and ecosystems that depend on it.
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Lensky, Itamar M., e Ron Drori. "A Satellite-Based Parameter to Monitor the Aerosol Impact on Convective Clouds". Journal of Applied Meteorology and Climatology 46, n. 5 (1 maggio 2007): 660–66. http://dx.doi.org/10.1175/jam2487.1.
Testo completoAbstract (sommario):
Abstract A method to monitor the aerosol impact on convective clouds using satellite data is presented. The impacts of forest fires and highly polluting megacities on cloud precipitation formation processes are quantified by the vertical extent above cloud base to which convective cloud tops have to develop for onset of precipitation in terms of temperature difference D15. Large D15 is a manifestation of the precipitation suppression effect of small cloud condensation nuclei aerosols that elevate the altitude where effective precipitation processes are initiated. A warmer land surface with a greater sensible heat flux that increases the updraft velocity at cloud base may also contribute to the same effect. Therefore, D15 is greater for clouds that develop over more polluted and/or warmer surfaces that result from smoke and urban pollution and/or urban heat island, respectively. The precipitation suppression effects of both smoke from forest fires and urban effects can be vividly seen in a case study over Southeast Asia. Typical values of D15 are 1°–6°C for tropical maritime clouds, 8°–15°C for tropical clouds over land, 16°–26°C for urban air pollution, and 18°–39°C for clouds ingesting smoke from forest fires.
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Van Beusekom, Ashley E., Grizelle González e Martha A. Scholl. "Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change". Atmospheric Chemistry and Physics 17, n. 11 (16 giugno 2017): 7245–59. http://dx.doi.org/10.5194/acp-17-7245-2017.
Testo completoAbstract (sommario):
Abstract. The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100 m altitude in the forest upwind of the TMCF that occupies an altitude range from ∼ 600 m to the peaks at 1100 m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS) ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI), and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600 m, from 740 to 964 m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ∼ 200–600 m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic-scale weather patterns that increase frequency of drought periods during the wet seasons (periods of higher cloud base) may also impact ecosystem health.
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Rebertus, Alan J. "Crown Shyness in a Tropical Cloud Forest". Biotropica 20, n. 4 (dicembre 1988): 338. http://dx.doi.org/10.2307/2388326.
Testo completo
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Duflot, Valentin, Pierre Tulet, Olivier Flores, Christelle Barthe, Aurélie Colomb, Laurent Deguillaume, Mickael Vaïtilingom et al. "Preliminary results from the FARCE 2015 campaign: multidisciplinary study of the forest–gas–aerosol–cloud system on the tropical island of La Réunion". Atmospheric Chemistry and Physics 19, n. 16 (21 agosto 2019): 10591–618. http://dx.doi.org/10.5194/acp-19-10591-2019.
Testo completoAbstract (sommario):
Abstract. The Forests gAses aeRosols Clouds Exploratory (FARCE) campaign was conducted in March–April 2015 on the tropical island of La Réunion. For the first time, several scientific teams from different disciplines collaborated to provide reference measurements and characterization of La Réunion vegetation, volatile organic compounds (VOCs), biogenic VOCs (BVOCs), (bio)aerosols and composition of clouds, with a strong focus on the Maïdo mountain slope area. The main observations obtained during this 2-month intensive field campaign are summarized. They include characterizations of forest structure, concentrations of VOCs and precursors emitted by forests, aerosol loading and optical properties in the planetary boundary layer (PBL), formation of new particles by nucleation of gas-phase precursors, ice-nucleating particles concentrations, and biological loading in both cloud-free and cloudy conditions. Simulations and measurements confirm that the Maïdo Observatory lies within the PBL from late morning to late evening and that, when in the PBL, the main primary sources impacting the Maïdo Observatory are of marine origin via the Indian Ocean and of biogenic origin through the dense forest cover. They also show that (i) the marine source prevails less and less while reaching the observatory; (ii) when in the PBL, depending on the localization of a horizontal wind shear, the Maïdo Observatory can be affected by air masses coming directly from the ocean and passing over the Maïdo mountain slope, or coming from inland; (iii) bio-aerosols can be observed in both cloud-free and cloudy conditions at the Maïdo Observatory; (iv) BVOC emissions by the forest covering the Maïdo mountain slope can be transported upslope within clouds and are a potential cause of secondary organic aerosol formation in the aqueous phase at the Maïdo Observatory; and (v) the simulation of dynamics parameters, emitted BVOCs and cloud life cycle in the Meso-NH model are realistic, and more advanced Meso-NH simulations should use an increased horizontal resolution (100 m) to better take into account the orography and improve the simulation of the wind shear front zone within which lies the Maïdo Observatory. Using various observations and simulations, this work draws up an inventory of the in situ studies that could be performed in La Réunion and at the Maïdo Observatory. It also aims to develop scientific collaborations and to support future scientific projects in order to better understand the forest–gas–aerosol–cloud system in an insular tropical environment.
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Pedraza, Rosa-Amelia, Guadalupe Williams-Linera e Teresa Nicolás-Silva. "Vegetation structure and biodiversity recovery in 19-year-old active restoration plantations in a Neotropical cloud forest". Forest Systems 30, n. 1 (12 marzo 2021): 3004. http://dx.doi.org/10.5424/fs/2021301-17131.
Testo completoAbstract (sommario):
Aim of the study: To evaluate how middle-aged active restoration plantations of native tree species contribute to the recovery of the tropical cloud forest in terms of vegetation structure, tree richness, species composition, and to shade-tolerance and seed dispersal mode functional groups.Area of the study: We studied two 19-year-old active restoration sites and their reference mature forests in the tropical montane cloud forest belt, Veracruz, Mexico.Materials and methods: The basal area, density and height as well as the tree species composition and number of species and individuals classified by shade tolerance (pioneer and non-pioneer trees), and seed dispersal mode (anemochorous, barochorous-synzoochorous and endozoochorous) were compared between active restoration plantations and reference forests.Main results: Planted trees and the woody vegetation growing under them represented a high proportion of reference forests’ basal area. Tree richness and Shannon’s equitability index were similar in both reference forests and one active restoration plantation and slightly different in the other. Tree species composition differed among sites; however, each 19-year-old plantation already had several non-pioneer species and a similar species proportion of the seed dispersal syndromes present in their reference forests.Research highlights: Active restoration accelerated the recovery of cloud forest in degraded pasture and bracken fern lands. Planted trees promoted the rapid development of vegetation structure and natural tree regeneration. Although species composition is still different, these middle-aged restoration plantations already have forest species and a proportion of functional groups of species similar to those of their own reference montane cloud forests.Keywords: active restoration; forest recovery; passive restoration; seed dispersal mode; succession; tree species; tropical montane cloud forest.
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Lawton, Robert O. "Canopy gaps and light penetration into a wind-exposed tropical lower montane rain forest". Canadian Journal of Forest Research 20, n. 5 (1 maggio 1990): 659–67. http://dx.doi.org/10.1139/x90-088.
Testo completoAbstract (sommario):
Penetration of light into the understory of tropical lower montane rain forests at Monteverde, Costa Rica, depends largely on the nature of canopy disruption by limb fall and tree fall. Midday photosynthetic photon flux densities (PPFD) above the forest canopy are low because of cloud cover (modal values are 400–500 μmol•m−2•s−1; daily integrations are 19 mol•m−2). The proportion of above-canopy PPFD that penetrates to the understory is greater in the elfin forests on wind-exposed ridge crests than in taller cloud forests in protected ravines (39 and 54% of understory locations receive <2% PPFD, respectively). PPFD is higher, and its vertical gradients steeper, in elfin forest gaps than in gaps of the same area in the taller forest. Gaps may or may not influence PPFD in adjacent forest understory, depending on vegetation structure on the gap periphery. In the taller cloud forest, understory PPFD is not correlated with distance to the nearest gap, but in the elfin forest it is (r = −0.467). This variation in the light environment is an integral part of disturbance and regrowth in these forests and seems to have played a major role in the evolution of tree growth strategies.
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Nair, Udaysankar S., Salvi Asefi, Ronald M. Welch, D. K. Ray, Robert O. Lawton, Vani Starry Manoharan, Mark Mulligan, Tom L. Sever, Daniel Irwin e J. Alan Pounds. "Biogeography of Tropical Montane Cloud Forests. Part II: Mapping of Orographic Cloud Immersion". Journal of Applied Meteorology and Climatology 47, n. 8 (1 agosto 2008): 2183–97. http://dx.doi.org/10.1175/2007jamc1819.1.
Testo completoAbstract (sommario):
Abstract This study details two unique methods to quantify cloud-immersion statistics for tropical montane cloud forests (TMCFs). The first technique uses a new algorithm for determining cloud-base height using Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products, and the second method uses numerical atmospheric simulation along with geostationary satellite data. Cloud-immersion statistics are determined using MODIS data for March 2003 over the study region consisting of Costa Rica, southern Nicaragua, and northern Panama. Comparison with known locations of cloud forests in northern Costa Rica shows that the MODIS-derived cloud-immersion maps successfully identify known cloud-forest locations in the United Nations Environment Programme (UNEP) World Conservation Monitoring Centre (WCMC) database. Large connected regions of cloud immersion are observed in regions in which the trade wind flow is directly impinging upon the mountain slopes; in areas in which the flow is parallel to the slopes, a fractured spatial distribution of TMCFs is observed. Comparisons of the MODIS-derived cloud-immersion map with the model output show that the MODIS product successfully captures the important cloud-immersion patterns in the Monteverde region of Costa Rica. The areal extent of cloud immersion is at a maximum during morning hours and at a minimum during the afternoon, before increasing again in the evening. Cloud-immersion frequencies generally increase with increasing elevation and tend to be higher on the Caribbean Sea side of the mountains. This study shows that the MODIS data may be used successfully to map the biogeography of cloud forests and to quantify cloud immersion over cloud-forest locations.
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Paoletti, Maurizio G., R. A. J. Taylor, Benjamin R. Stinner, Deborah H. Stinner e David H. Benzing. "Diversity of soil fauna in the canopy and forest floor of a Venezuelan cloud forest". Journal of Tropical Ecology 7, n. 3 (agosto 1991): 373–83. http://dx.doi.org/10.1017/s0266467400005654.
Testo completoAbstract (sommario):
ABSTRACTArboreal and terresterial soil and lilter were sampled for macro-and microinvertebrates at two locations in a Venezuelan cloud forest. Fauna were most abundant in forest floor soil and associated litter. However, media suspended in the canopy and particularly those trapped in bromeliad shoots were most densely populated, while the diversities of the arboreal and terrestrial soil fauna were indistinguishable. Rates of leaf litter decomposition in the arboreal and terrestrial soils were similar, but the arboreal soils contained higher concentrations of mineral nutrients and carbon. Implications of these findings for the definition of soil in humid tropical forests, and related differences between temperate and tropical forests are discussed. The similarities in diversity and differences in species composition between arboreal and terrestrial soil fauna raise questions concerning the evolution of tropical soil fauna, as well as the estimate of global biotic diversity.
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Abril, Adriana B., e Enrique H. Bucher. "Variation in soil biological characteristics on an elevational gradient in the montane forest of north-west Argentina". Journal of Tropical Ecology 24, n. 4 (luglio 2008): 457–61. http://dx.doi.org/10.1017/s0266467408005154.
Testo completoAbstract (sommario):
Montane tropical and subtropical rain forests are complex ecosystems, characterized by marked rainfall and temperature gradients with altitude, which in turn control the vegetation altitudinal zones (Hueck 1978). Montane forests are often referred to as cloud forests in recognition of the important influence of a dense and frequent cloud cover that conditions forest structure and functioning (Bautista-Cruz & del Castillo 2005, Holder 2004).
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Hulshof, Catherine M., Bonnie G. Waring, Jennifer S. Powers e Susan P. Harrison. "Trait‐based signatures of cloud base height in a tropical cloud forest". American Journal of Botany 107, n. 6 (giugno 2020): 886–94. http://dx.doi.org/10.1002/ajb2.1483.
Testo completo
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Nazarova, Tatiana, Pascal Martin e Gregory Giuliani. "Monitoring Vegetation Change in the Presence of High Cloud Cover with Sentinel-2 in a Lowland Tropical Forest Region in Brazil". Remote Sensing 12, n. 11 (5 giugno 2020): 1829. http://dx.doi.org/10.3390/rs12111829.
Testo completoAbstract (sommario):
Forests play major roles in climate regulation, ecosystem services, carbon storage, biodiversity, terrain stabilization, and water retention, as well as in the economy of numerous countries. Nevertheless, deforestation and forest degradation are rampant in many parts of the world. In particular, the Amazonian rainforest faces the constant threats posed by logging, mining, and burning for agricultural expansion. In Brazil, the “Sete de Setembro Indigenous Land”, a protected area located in a lowland tropical forest region at the border between the Mato Grosso and Rondônia states, is subject to illegal deforestation and therefore necessitates effective vegetation monitoring tools. Optical satellite imagery, while extensively used for landcover assessment and monitoring, is vulnerable to high cloud cover percentages, as these can preclude analysis and strongly limit the temporal resolution. We propose a cloud computing-based coupled detection strategy using (i) cloud and cloud shadow/vegetation detection systems with Sentinel-2 data analyzed on the Google Earth Engine with deep neural network classification models, with (ii) a classification error correction and vegetation loss and gain analysis tool that dynamically compares and updates the classification in a time series. The initial results demonstrate that such a detection system can constitute a powerful monitoring tool to assist in the prevention, early warning, and assessment of deforestation and forest degradation in cloudy tropical regions. Owing to the integrated cloud detection system, the temporal resolution is significantly improved. The limitations of the model in its present state include classification issues during the forest fire period, and a lack of distinction between natural vegetation loss and anthropogenic deforestation. Two possible solutions to the latter problem are proposed, namely, the mapping of known agricultural and bare areas and its subsequent removal from the analyzed data, or the inclusion of radar data, which would allow a large amount of finetuning of the detection processes.
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Guevara, Lázaro. "Altitudinal, latitudinal and longitudinal responses of cloud forest species to Quaternary glaciations in the northern Neotropics". Biological Journal of the Linnean Society 130, n. 3 (10 giugno 2020): 615–25. http://dx.doi.org/10.1093/biolinnean/blaa070.
Testo completoAbstract (sommario):
Abstract The glaciations of the Quaternary caused changes in the geographical distributions of species associated with tropical montane cloud forests. The most obvious effect of the glacial conditions was the downward displacement of cloud forest species, thus giving opportunities for population connectivity in the lowlands. Considerable attention has been paid to these altitudinal changes, but latitudinal and longitudinal movements remain poorly understood in the northern Neotropics. Here, I use ecological niche modelling to generate palaeodistributions of small-eared shrews (Mammalia: Soricidae) closely associated with cloud forests in the mountain systems of Mexico and then retrodict their range shifts during the Last Glacial Maximum (LGM), one of the coldest periods of the Quaternary. The results suggest that cloud forest species not only migrated downwards in response to global cooling and dryness but also migrated latitudinally and longitudinally onto those slopes that maintained moist conditions (other slopes remained unsuitable during the LGM), thus revealing a hitherto unknown route for postglacial colonization of cloud forest species. This scenario of past distributional change probably had genetic and demographic implications and has repercussions for the identification of areas of refugia and postglacial colonization routes of cloud forest species.
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Becker, C. Dustin, Thomas M. Loughin e Tatiana Santander. "Identifying forest-obligate birds in tropical moist cloud forest of Andean Ecuador". Journal of Field Ornithology 79, n. 3 (settembre 2008): 229–44. http://dx.doi.org/10.1111/j.1557-9263.2008.00184.x.
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Lara-Tufiño, José Daniel, Luis M. Badillo-Saldaña, Raquel Hernández-Austria e Aurelio Ramírez-Bautista. "Effects of traditional agroecosystems and grazing areas on amphibian diversity in a region of central Mexico". PeerJ 7 (15 febbraio 2019): e6390. http://dx.doi.org/10.7717/peerj.6390.
Testo completoAbstract (sommario):
Habitat loss or degradation due to land cover change is regarded as one of the main drivers of amphibian decline; therefore, it is imperative to assess the effects of land-cover change on this group of vertebrates. In this study, we analyze changes in alpha and beta diversity of amphibian communities found in five land-cover types: mountain cloud forest, tropical evergreen forest, shade coffee, milpa huasteca, and grazing areas; six samples sites were established for each land-cover type, separated at least one km away. The study was conducted in the northwest part of the state of Hidalgo, in a transition zone between the Sierra Madre Oriental and the Gulf of Mexico, which is a region rich in amphibian species. The results indicate that alpha diversity decreases with loss of canopy cover, this being high in mountain cloud forest, tropical evergreen forest, and Shade coffee, and low in milpa huasteca and grazing areas. The land-cover type with the highest species evenness was found in milpa huasteca and the lowest in. The highest beta diversity was observed among tropical evergreen forest and grazing areas. Mountain cloud forest contains both exclusive species and the highest number of species currently regarded as threatened by national and international conservation assessment systems. In order to preserve amphibian diversity in the study area it is vital to protect the last remnants of native vegetation, especially mountain cloud forest, but also including Shade coffee, since the latter habitat harbors amphibian diversity similar to that found in native forests. Finally, implementation of policies that both reduce Grazing areas and increase their productivity is also necessary, since these highly modified areas turn out to be the ones that affect amphibian diversity the most.
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Knapp, Sandra. "Monteverde. Ecology and Conservation of a Tropical Cloud Forest". Biological Conservation 97, n. 1 (gennaio 2001): 128. http://dx.doi.org/10.1016/s0006-3207(00)00096-3.
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Cuenca, Gisela, Rafael Herrera e Ernesto Medina. "Aluminium tolerance in trees of a tropical cloud forest". Plant and Soil 125, n. 2 (luglio 1990): 169–75. http://dx.doi.org/10.1007/bf00010654.
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García-Santos, G. "Transpiration in a sub-tropical ridge-top cloud forest". Journal of Hydrology 462-463 (settembre 2012): 42–52. http://dx.doi.org/10.1016/j.jhydrol.2011.08.069.
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Couto-Santos, Fabiana Rita do, e Flávio J. Luizão. "Fine litter accumulation in Central Amazonian Tropical Rainforest canopy". Acta Amazonica 40, n. 4 (dicembre 2010): 781–86. http://dx.doi.org/10.1590/s0044-59672010000400021.
Testo completoAbstract (sommario):
Fine litter dynamics within the canopy differ from litter dynamics on the forest floor for reasons such as differences in microclimate, substrate, disturbance level, stratum influence and decomposition rates. This study is the first attempt to quantify the fine litter accumulated in the canopy of Central Amazonian forests. We compared the canopy litter accumulation to fine litter-layer on forest floor and to other forests and also investigated which were the mostly accumulated litter omponents. We found that Central Amazonian Rainforest intercepts greater fine litter in the canopy (294 g.m-2) compared to other forest formations with higher winds speed as in a Costa Rican Cloud Forest (170 g.m-2). The mean canopy fine litter accumulated at the end of the dry season was less than a half of that on soil surface (833 g.m-2) and the fine wood component dominates the canopy samplings (174 g.m-2) while leafy component predominate on soil surface litter (353 g.m-2).
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Rosenfeld, D., G. Liu, X. Yu, Y. Zhu, J. Dai, X. Xu e Z. Yue. "High resolution (375 m) cloud microstructure as seen from the NPP/VIIRS Satellite imager". Atmospheric Chemistry and Physics Discussions 13, n. 11 (13 novembre 2013): 29845–94. http://dx.doi.org/10.5194/acpd-13-29845-2013.
Testo completoAbstract (sommario):
Abstract. The VIIRS (Visible Infrared Imaging Radiometer Suite) onboard the Suomi NPP (National Polar-Orbiting Partnership) satellite has improved resolution of 750 m with respect to 1000 m of the MODerate-resolution Imaging Spectroradiometer, for the channels that allow retrieving cloud microphysical parameters such as cloud drop effective radius (re). The VIIRS has also an imager with 5 channels of double resolution of 375 m, which was not designed for retrieving cloud products. A methodology for a high resolution retrieval of re and microphysical presentation of the cloud field based on the VIIRS imager was developed and evaluated with respect to MODIS in this study. The tripled microphysical resolution with respect to MODIS allows obtaining new insights for cloud aerosol interactions, especially at the smallest cloud scales, because the VIIRS imager can resolve the small convective elements that are sub-pixel for MODIS cloud products. Examples are given for new insights on ship tracks in marine stratocumulus, pollution tracks from point and diffused sources in stratocumulus and cumulus clouds over land, deep tropical convection in pristine air mass over ocean and land, tropical clouds that develop in smoke from forest fires and in heavy pollution haze over densely populated regions in southeast Asia, and for pyro-cumulonimbus clouds. It is found that the VIIRS imager provides more robust physical interpretation and refined information for cloud and aerosol microphysics as compared to MODIS, especially in the initial stage of cloud formation. VIIRS is found to identify much more full-cloudy pixels when small boundary layer convective elements are present. This, in turn, allows a better quantification of cloud aerosol interactions and impacts on precipitation forming processes.
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Rosenfeld, D., G. Liu, X. Yu, Y. Zhu, J. Dai, X. Xu e Z. Yue. "High-resolution (375 m) cloud microstructure as seen from the NPP/VIIRS satellite imager". Atmospheric Chemistry and Physics 14, n. 5 (10 marzo 2014): 2479–96. http://dx.doi.org/10.5194/acp-14-2479-2014.
Testo completoAbstract (sommario):
Abstract. VIIRS (Visible Infrared Imaging Radiometer Suite), onboard the Suomi NPP (National Polar-orbiting Partnership) satellite, has an improved resolution of 750 m with respect to the 1000 m of the Moderate Resolution Imaging Spectroradiometer for the channels that allow retrieving cloud microphysical parameters such as cloud drop effective radius (re). VIIRS also has an imager with five channels of double resolution of 375 m, which was not designed for retrieving cloud products. A methodology for a high-resolution retrieval of re and microphysical presentation of the cloud field based on the VIIRS imager was developed and evaluated with respect to MODIS in this study. The tripled microphysical resolution with respect to MODIS allows obtaining new insights for cloud–aerosol interactions, especially at the smallest cloud scales, because the VIIRS imager can resolve the small convective elements that are sub-pixel for MODIS cloud products. Examples are given for new insights into ship tracks in marine stratocumulus, pollution tracks from point and diffused sources in stratocumulus and cumulus clouds over land, deep tropical convection in pristine air mass over ocean and land, tropical clouds that develop in smoke from forest fires and in heavy pollution haze over densely populated regions in southeastern Asia, and for pyro-cumulonimbus clouds. It is found that the VIIRS imager provides more robust physical interpretation and refined information for cloud and aerosol microphysics as compared to MODIS, especially in the initial stage of cloud formation. VIIRS is found to identify significantly more fully cloudy pixels when small boundary layer convective elements are present. This, in turn, allows for a better quantification of cloud–aerosol interactions and impacts on precipitation-forming processes.
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Mejía-Domínguez, Nancy R., Jorge A. Meave e Carlos A. Ruiz-Jiménez. "Análisis estructural de un bosque mesófilo de montaña en el extremo oriental de la Sierra Madre del Sur (Oaxaca), México". Botanical Sciences, n. 74 (2 giugno 2017): 13. http://dx.doi.org/10.17129/botsci.1684.
Testo completoAbstract (sommario):
We analyzed vegetation structure in a 1-ha plot of cloud forest at Santo Tomás Teipan (Oaxaca, Mexico). Considering its marginal location near the edge of a region covered by this vegetation type on the Sierra Madre del Sur, we examined to what extent this community differed from other cloud forest communities thriving under better conditions for this plant formation. Each individual with diameter at breast height (DBH) ≥2.5 cm was located in a system of coordinates; besides, its taxonomic identity, crown cover, DBH and total height as well as the height to the first branch and the crown base were recorded. Basal area (46.41 m2 ha-1), cover (44,247.33 m2 ha-1), and density (1,035 ind. ha-1) figures fall within the known range for the lower montane rain forests of tropical America. According to structure and composition, two strata were differentiated: a lower one (2 to 11 m), and an upper one (11 to 30 m). Overall dominance corresponded to Cornus disciflora, an upper stratum species. In the plot two topographic conditions were distinguished, namely lower ravine slope and hilltop, which seem to be associated to contrasting soil characteristics. Although this topographic heterogeneity does not match the structural homogeneity of the forest, we detected some clumped patterns for individual species that were preferentially distributed in one of these conditions. The structure of the forest at Teipan is comparable to that of similar forests, but its diversity is relatively low. This may be explained by the absence of taxa occurring in the adjacent dry tropical communities, unlike other cloud forests whose flora appears to be enriched with some elements typical of tropical moist communities with which they abut.
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Morera Beita, Carlos, Luis Fernando Sandoval Murillo e Josep Pinto Fusaba. "Transformaciones espacio-temporales de la cobertura vegetal en el Parque Nacional Corcovado, 1960- 2014". Revista de Biología Tropical 66, n. 1 (13 dicembre 2017): 352. http://dx.doi.org/10.15517/rbt.v66i1.28925.
Testo completoAbstract (sommario):
Regional studies evaluating spatial-temporal transformations of vegetation in Costa Rica, especially within National Parks, are scarce. Therefore, this paper analyses the vegetation distribution during 1960, 1976, 1997 and 2014 in the Corcovado National Park. This protected area is located in the Osa Peninsula, Costa Rica, and represents the Northern most tropical rain forest on the Pacific coast of America. This area offers a great wealth of biodiversity due to its geological formation, isolation for long time periods, and its particular climatic conditions that generate unique ecosystems such as cloud forests associated with ocean situated close to hill breezes located over 500 m a.s.l., as well as dense tropical forest. This study evaluates the spatial distribution of vegetation based on maps that resulted from the process of photo-interpretation of 1960, 1976, 1997 and 2012, as well as from the landscape index analysis. It concludes that during the study period, the vegetation changes have been minimal. Instead, in the few areas impacted by human activity (small-scale agriculture and pasture lands) an ecological restoration has occurred during recent decades. In addition, this research suggests that the recovering forest cover within the park and even within the Osa Peninsula has been expanding the cloud forest. An increase and contraction relationship between the different categories (Cloud forest and forests as well of flooded forest and forest in flat zones) was found. Furthermore, this study suggests the need of permanent plots in order to monitor vegetation and identify the factors that explain this previous process.
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Peng, Xi, Anjiu Zhao, Yongfu Chen, Qiao Chen e Haodong Liu. "Tree Height Measurements in Degraded Tropical Forests Based on UAV-LiDAR Data of Different Point Cloud Densities: A Case Study on Dacrydium pierrei in China". Forests 12, n. 3 (11 marzo 2021): 328. http://dx.doi.org/10.3390/f12030328.
Testo completoAbstract (sommario):
Tropical forest degradation is a major contributor to greenhouse gas emissions. Tree height can be used as an important predictor of forest growth, and yield models can provide basic data for forest degradation assessments. As an important parameter of unmanned aerial vehicle-light detection and ranging (UAV-LiDAR), it is not clear how the point cloud density affects the extraction accuracy of tree height in degraded tropical rain forests. To solve this problem, we collected UAV-LiDAR data at a flight altitude of 150 m, and then resampled the UAV-LiDAR data obtained according to the point cloud density percentage resampling method and obtained UAV-LiDAR data for five different point cloud densities, namely, 12, 17, 28, 64, and 108 points/m2. On the basis of the resampled LiDAR data, we generated a canopy height model (CHM) to extract the height of Dacrydium pierrei (D. pierrei). The results show that (1) With the increase in the point cloud density, the accuracy of tree height extraction gradually increased, with a maximum accuracy at 108 points/m2 (root mean squared error (RMSE)% = 22.78%, bias% = 14.86%). The accuracy (RMSE%) increased by 6.92% as the point cloud density increased from 12 points/m2 to 17 points/m2, but only increased by 0.99% as the point cloud density increased from 17 points/m2 to 108 points/m2, indicating that 17 points/m2 is a critical point for tree height extraction of D. pierrei. (2) Compared with the results from broad-leaved forests, the accuracy of D. pierrei height extraction from coniferous forest was higher. With the increase in point cloud density, the difference in the accuracy of D. pierrei height between two stands gradually increased. When the point cloud density was 108 points/m2, the differences in RMSE% and bas% were 3.55% and 6.22%, respectively. When the point cloud density was 12 points/m2, the differences in RMSE% and bias% were 2.71% and 4.69%, respectively. Our research identified the lowest LiDAR data point cloud density required to ensure a certain accuracy in tree height extraction, which will help scholars formulate UAV-LiDAR forest resource survey plans.
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Nadkarni, Nalini M., Teri J. Matelson e William A. Haber. "Structural characteristics and floristic composition of a Neotropical cloud forest, Monteverde, Costa Rica". Journal of Tropical Ecology 11, n. 4 (novembre 1995): 481–95. http://dx.doi.org/10.1017/s0266467400009020.
Testo completoAbstract (sommario):
ABSTRACTThe Monteverde Cloud Forest Reserve protects a variety of primary montane forest communities on volcanic parent materials. We describe the structure and composition of the forest to provide background information for epiphyte and nutrient cycling studies and for comparison with other tropical montane forests. In a 4-ha study plot in leeward cloud forest, density of stems (2062 individuals ha−1 for stems >2 cm dbh, 555 individuals ha−1 for stems > 10cm dbh) and stem basal area (73.8 m2 ha−1 for stems >2 cm, 62.0 m2 ha−1 for stems >10 cm dbh) were high relative to other montane forests. Stems in a subset of the plot (c. 1/3 of the area) were identified and assigned to 47 families, 83 genera and 114 species, which is rich compared with other montane forests. Large stems had a higher spatial variability of structural and floristic characteristics than small stems.
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Sanchez, Alber Hamersson, Michelle Cristina A. Picoli, Gilberto Camara, Pedro R. Andrade, Michel Eustaquio D. Chaves, Sarah Lechler, Anderson R. Soares et al. "Comparison of Cloud Cover Detection Algorithms on Sentinel–2 Images of the Amazon Tropical Forest". Remote Sensing 12, n. 8 (18 aprile 2020): 1284. http://dx.doi.org/10.3390/rs12081284.
Testo completoAbstract (sommario):
Tropical forests regulate the global water and carbon cycles and also host most of the world’s biodiversity. Despite their importance, they are hard to survey due to their location, extent, and particularly, their cloud coverage. Clouds hinder the spatial and radiometric correction of satellite imagery and also diminishing the useful area on each image, making it difficult to monitor land change. For this reason, our purpose is to identify the cloud detection algorithm best suited for the Amazon rainforest on Sentinel–2 images. To achieve this, we tested four cloud detection algorithms on Sentinel–2 images spread in five areas of the Amazonia. Using more than eight thousand validation points, we compared four cloud detection methods: Fmask 4, MAJA, Sen2Cor, and s2cloudless. Our results point out that FMask 4 has the best overall accuracy on images of the Amazon region (90%), followed by Sen2Cor’s (79%), MAJA (69%), and S2cloudless (52%). We note the choice of method depends on the intended use. Since MAJA reduces the number of false positives by design, users that aim to improve the producer’s accuracy should consider its use.
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Hernández-Dávila, Omar, Javier Laborde, Vinicio J. Sosa, Claudia Gallardo-Hernández e Cecilia Díaz-Castelazo. "Forested riparian belts as reservoirs of plant species in fragmented landscapes of tropical mountain cloud forest". Botanical Sciences 98, n. 2 (1 giugno 2020): 288–304. http://dx.doi.org/10.17129/botsci.2497.
Testo completoAbstract (sommario):
Background: Cloud forest in central Veracruz is highly fragmented. However, different arboreal elements are still present within the agricultural matrix, including small patches of secondary forest, isolated trees and forested riparian belts. These elements could be important for cloud forest species conservation.
Questions: What is the structure and composition of forested riparian belts within current anthropic landscapes, and what is their potential contribution as reservoirs of mountain cloud forest native plant species?
Studied species: Vegetation community of forested riparian belts of cloud forest.
Study site and dates: Eastern Mexico (central Veracruz), January to November 2018
Methods: Along 14 segments of riparian belts (≈400 m long), distributed across different tributary streams, six 50 × 2 m transects were placed (three per riverside) per segment. Every plant rooted within a transect and ≥ 1.5 m in height was identified and measured (height and DBH).
Results: A total of 2,062 plants from 161 species, 102 genera and 55 families were recorded in the 14 sites (8,400 m² sampled). Structural attributes and floristic composition varied widely amongst sites. Elevation and the amount of forest cover (i.e., area) within 500 m of each sampling site were the most important factors underlying the spatial variation in species composition.
Conclusions: Riparian belts were remarkably heterogeneous harboring a notable richness of tree and shrub species many of them native of the original cloud forest. This diversity reveals that these arboreal elements are keystone structures for biodiversity conservation and also have a high potential as propagule sources for cloud forest restoration in anthropic landscapes.
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Fahey, Timothy J., Ruth E. Sherman e Edmund V. J. Tanner. "Tropical montane cloud forest: environmental drivers of vegetation structure and ecosystem function". Journal of Tropical Ecology 32, n. 5 (9 novembre 2015): 355–67. http://dx.doi.org/10.1017/s0266467415000176.
Testo completoAbstract (sommario):
Abstract:Tropical montane cloud forests (TMCF) are characterized by short trees, often twisted with multiple stems, with many stems per ground area, a large stem diameter to height ratio, and small, often thick leaves. These forests exhibit high root to shoot ratio, with a moderate leaf area index, low above-ground production, low leaf nutrient concentrations and often with luxuriant epiphytic growth. These traits of TMCF are caused by climatic conditions not geological substrate, and are particularly associated with frequent or persistent fog and low cloud. There are several reasons why fog might result in these features. Firstly, the fog and clouds reduce the amount of light received per unit area of ground and as closed-canopy forests absorb most of the light that reaches them the reduction in the total amount of light reduces growth. Secondly, the rate of photosynthesis per leaf area declines in comparison with that in the lowlands, which leads to less carbon fixation. Nitrogen supply limits growth in several of the few TMCFs where it has been investigated experimentally. High root : shoot biomass and production ratios are common in TMCF, and soils are often wet which may contribute to N limitation. Further study is needed to clarify the causes of several key features of TMCF ecosystems including high tree diameter : height ratio.
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Arriaga, Laura. "Gap Dynamics of a Tropical Cloud Forest in Northeastern Mexico". Biotropica 20, n. 3 (settembre 1988): 178. http://dx.doi.org/10.2307/2388232.
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Wenny, D. G., e D. J. Levey. "Directed seed dispersal by bellbirds in a tropical cloud forest". Proceedings of the National Academy of Sciences 95, n. 11 (26 maggio 1998): 6204–7. http://dx.doi.org/10.1073/pnas.95.11.6204.
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Thomas, Daniel C., Roo Vandegrift, Ashley Ludden, George C. Carroll e Bitty A. Roy. "Spatial Ecology of the Fungal GenusXylariain a Tropical Cloud Forest". Biotropica 48, n. 3 (18 gennaio 2016): 381–93. http://dx.doi.org/10.1111/btp.12273.
Testo completo
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Kuck, Tahisa Neitzel, Edson Eyji Sano, Polyanna da Conceição Bispo, Elcio Hideiti Shiguemori, Paulo Fernando Ferreira Silva Filho e Eraldo Aparecido Trondoli Matricardi. "A Comparative Assessment of Machine-Learning Techniques for Forest Degradation Caused by Selective Logging in an Amazon Region Using Multitemporal X-Band SAR Images". Remote Sensing 13, n. 17 (24 agosto 2021): 3341. http://dx.doi.org/10.3390/rs13173341.
Testo completoAbstract (sommario):
The near-real-time detection of selective logging in tropical forests is essential to support actions for reducing CO2 emissions and for monitoring timber extraction from forest concessions in tropical regions. Current operating systems rely on optical data that are constrained by persistent cloud-cover conditions in tropical regions. Synthetic aperture radar data represent an alternative to this technical constraint. This study aimed to evaluate the performance of three machine learning algorithms applied to multitemporal pairs of COSMO-SkyMed images to detect timber exploitation in a forest concession located in the Jamari National Forest, Rondônia State, Brazilian Amazon. The studied algorithms included random forest (RF), AdaBoost (AB), and multilayer perceptron artificial neural network (MLP-ANN). The geographical coordinates (latitude and longitude) of logged trees and the LiDAR point clouds before and after selective logging were used as ground truths. The best results were obtained when the MLP-ANN was applied with 50 neurons in the hidden layer, using the ReLu activation function and SGD weight optimizer, presenting 88% accuracy both for the pair of images used for training (images acquired in June and October) of the network and in the generalization test, applied on a second dataset (images acquired in January and June). This study showed that X-band SAR images processed by applying machine learning techniques can be accurately used for detecting selective logging activities in the Brazilian Amazon.
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Flores Palacios, Alejandro, Juan E. Martínez Gómez e Robert L. Curry. "La vegetación de Isla Socorro, Archipiélago de Revillagigedo, México". Botanical Sciences 84 (20 maggio 2019): 13. http://dx.doi.org/10.17129/botsci.2288.
Testo completoAbstract (sommario):
Based on physiognomic criteria and a cluster analysis based on 90 plots (14 in prairie and grassland, 35 in shrubs, 38 in forest and 3 in secondary vegetation) we classified the vegetation of Socorro Island. In addition to coastal halophytes, we found evidence supporting eight primary vegetation types: <em>Conocarpus </em> shrubby vegetation, grassland, prairie, <em>Croton masonii </em> shrubby vegetation, <em>Pteridium-Dodonaea </em> shrub, tropical dry forest, tropical rain forest and lower montane cloud forest. Prairie and grassland associations are clearly associated with altitude. Depending on the dominant tree species, three different units could be identified within the tropical rain forest of the island. Our analysis resolved differences with previous classifications of the vegetation on Socorro Island and indicated that some shrubby vegetation, sometimes considered as a different vegetation type, represented instead early succession stages of the lower montane cloud forest. The classifi cation presented constitutes a tool to aid future studies of the flora and fauna of this insular region.
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Muñoz-Villers, L. E., e J. J. McDonnell. "Land use change effects on runoff generation in a humid tropical montane cloud forest region". Hydrology and Earth System Sciences 17, n. 9 (16 settembre 2013): 3543–60. http://dx.doi.org/10.5194/hess-17-3543-2013.
Testo completoAbstract (sommario):
Abstract. While tropical montane cloud forests (TMCF) provide critical hydrological services to downstream regions throughout much of the humid tropics, catchment hydrology and impacts associated with forest conversion in these ecosystems remain poorly understood. Here, we compare the annual, seasonal and event-scale streamflow patterns and runoff generation processes of three neighbouring headwater catchments in central Veracruz (eastern Mexico) with similar pedological and geological characteristics, but different land cover: old-growth TMCF, 20 yr-old naturally regenerating TMCF and a heavily grazed pasture. We used a 2 yr record of high resolution rainfall and stream flow data (2008–2010) in combination with stable isotope and chemical tracer data collected for a series of storms during a 6-week period of increasing antecedent wetness (wetting-up cycle). Our results showed that annual and seasonal streamflow patterns in the mature and secondary forest were similar. In contrast, the pasture showed a 10% higher mean annual streamflow, most likely because of a lower rainfall interception. During the wetting-up cycle, storm runoff ratios increased at all three catchments (from 11 to 54% for the mature forest, 7 to 52% for the secondary forest and 3 to 59% for the pasture). With the increasing antecedent wetness, hydrograph separation analysis showed progressive increases of pre-event water contributions to total stormflow (from 35 to 99% in the mature forest, 26 to 92% in the secondary forest and 64 to 97% in the pasture). At all three sites, rainfall-runoff responses were dominated by subsurface flow generation processes for the majority of storms. However, for the largest and most intense storm (typically occurring once every 2 yr), sampled under wet antecedent conditions, the event water contribution in the pasture (34% on average) was much higher than in the forests (5% on average), indicating that rainfall infiltration capacity of the pasture was exceeded. This result suggests that despite the high permeability of the volcanic soils and underlying substrate in this TMCF environment, the conversion of forest to pasture may lead to important changes in runoff generation processes during large and high intensity storms. On the other hand, our results also showed that 20 yr of natural regeneration may be enough to largely restore the original hydrological conditions of this TMCF.
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Díaz-García, Juan Manuel, Fabiola López-Barrera, Eduardo Pineda, Tarin Toledo-Aceves e Ellen Andresen. "Comparing the success of active and passive restoration in a tropical cloud forest landscape: A multi-taxa fauna approach". PLOS ONE 15, n. 11 (10 novembre 2020): e0242020. http://dx.doi.org/10.1371/journal.pone.0242020.
Testo completoAbstract (sommario):
Tropical forest restoration initiatives are becoming more frequent worldwide in an effort to mitigate biodiversity loss and ecosystems degradation. However, there is little consensus on whether an active or a passive restoration strategy is more successful for recovering biodiversity because few studies make adequate comparisons. Furthermore, studies on animal responses to restoration are scarce compared to those on plants, and those that assess faunal recovery often focus on a single taxon, limiting the generalization of results. We assessed the success of active (native mixed-species plantations) and passive (natural regeneration) tropical cloud forest restoration strategies based on the responses of three animal taxa: amphibians, ants, and dung beetles. We compared community attributes of these three taxa in a 23-year-old active restoration forest, a 23-year-old passive restoration forest, a cattle pasture, and a mature forest, with emphasis on forest-specialist species. We also evaluated the relationship between faunal recovery and environmental variables. For all taxa, we found that recovery of species richness and composition were similar in active and passive restoration sites. However, recovery of forest specialists was enhanced through active restoration. For both forests under restoration, similarity in species composition of all faunal groups was 60–70% with respect to the reference ecosystem due to a replacement of generalist species by forest-specialist species. The recovery of faunal communities was mainly associated with canopy and leaf litter covers. We recommend implementing active restoration using mixed plantations of native tree species and, whenever possible, selecting sites close to mature forest to accelerate the recovery of tropical cloud forest biodiversity. As active restoration is more expensive than passive restoration, both strategies might be used in a complementary manner at the landscape level to compensate for high implementation costs.
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Gotsch, Sybil G., Heidi Asbjornsen e Gregory R. Goldsmith. "Plant carbon and water fluxes in tropical montane cloud forests". Journal of Tropical Ecology 32, n. 5 (15 luglio 2016): 404–20. http://dx.doi.org/10.1017/s0266467416000341.
Testo completoAbstract (sommario):
Abstract:Tropical montane cloud forests (TMCFs) are dynamic ecosystems defined by frequent, but intermittent, contact with fog. The resultant microclimate can vary considerably over short spatial and temporal scales, affecting the ecophysiology of TMCF plants. We synthesized research to date on TMCF carbon and water fluxes at the scale of the leaf, plant and ecosystem and then contextualized this synthesis with tropical lowland forest ecosystems. Mean light-saturated photosynthesis was lower than that of lowland forests, probably due to the effects of persistent reduced radiation leading to shade acclimation. Scaled to the ecosystem, measures of annual net primary productivity were also lower. Mean rates of transpiration, from the scale of the leaf to the ecosystem, were also lower than in lowland sites, likely due to lower atmospheric water demand, although there was considerable overlap in range. Lastly, although carbon use efficiency appears relatively invariant, limited evidence indicates that water use efficiency generally increases with altitude, perhaps due to increased cloudiness exerting a stronger effect on vapour pressure deficit than photosynthesis. The results reveal clear differences in carbon and water balance between TMCFs and their lowland counterparts and suggest many outstanding questions for understanding TMCF ecophysiology now and in the future.
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Abbas, Sawaid, Man Sing Wong, Jin Wu, Naeem Shahzad e Syed Muhammad Irteza. "Approaches of Satellite Remote Sensing for the Assessment of Above-Ground Biomass across Tropical Forests: Pan-tropical to National Scales". Remote Sensing 12, n. 20 (14 ottobre 2020): 3351. http://dx.doi.org/10.3390/rs12203351.
Testo completoAbstract (sommario):
Tropical forests are acknowledged for providing important ecosystem services and are renowned as “the lungs of the planet Earth” due to their role in the exchange of gasses—particularly inhaling CO2 and breathing out O2—within the atmosphere. Overall, the forests provide 50% of the total plant biomass of the Earth, which accounts for 450–650 PgC globally. Understanding and accurate estimates of tropical forest biomass stocks are imperative in ascertaining the contribution of the tropical forests in global carbon dynamics. This article provides a review of remote-sensing-based approaches for the assessment of above-ground biomass (AGB) across the tropical forests (global to national scales), summarizes the current estimate of pan-tropical AGB, and discusses major advancements in remote-sensing-based approaches for AGB mapping. The review is based on the journal papers, books and internet resources during the 1980s to 2020. Over the past 10 years, a myriad of research has been carried out to develop methods of estimating AGB by integrating different remote sensing datasets at varying spatial scales. Relationships of biomass with canopy height and other structural attributes have developed a new paradigm of pan-tropical or global AGB estimation from space-borne satellite remote sensing. Uncertainties in mapping tropical forest cover and/or forest cover change are related to spatial resolution; definition adapted for ‘forest’ classification; the frequency of available images; cloud covers; time steps used to map forest cover change and post-deforestation land cover land use (LCLU)-type mapping. The integration of products derived from recent Synthetic Aperture Radar (SAR) and Light Detection and Ranging (LiDAR) satellite missions with conventional optical satellite images has strong potential to overcome most of these uncertainties for recent or future biomass estimates. However, it will remain a challenging task to map reference biomass stock in the 1980s and 1990s and consequently to accurately quantify the loss or gain in forest cover over the periods. Aside from these limitations, the estimation of biomass and carbon balance can be enhanced by taking account of post-deforestation forest recovery and LCLU type; land-use history; diversity of forest being recovered; variations in physical attributes of plants (e.g., tree height; diameter; and canopy spread); environmental constraints; abundance and mortalities of trees; and the age of secondary forests. New methods should consider peak carbon sink time while developing carbon sequestration models for intact or old-growth tropical forests as well as the carbon sequestration capacity of recovering forest with varying levels of floristic diversity.
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de la Rosa-Manzano, Edilia, Glenda Mendieta-Leiva, Antonio Guerra-Pérez, Karla María Aguilar-Dorantes, Leonardo Uriel Arellano-Méndez e Jorge Ariel Torres-Castillo. "Vascular Epiphytic Diversity in a Neotropical Transition Zone Is Driven by Environmental and Structural Heterogeneity". Tropical Conservation Science 12 (gennaio 2019): 194008291988220. http://dx.doi.org/10.1177/1940082919882203.
Testo completoAbstract (sommario):
Vascular epiphytes contribute significantly to tropical diversity. Research on the factors that determine vascular epiphytic diversity and composition in tropical areas is flourishing. However, these factors are entirely unknown in tropical-temperate transition zones, which represent the distribution limit of several epiphytic species. We assessed the degree to which climatic and structural variables determine the diversity of vascular epiphytic assemblages (VEAs) in a transition zone in Mexico: the El Cielo Biosphere Reserve. We found 12,103 epiphytic individuals belonging to 30 species and 15 genera along a climatic gradient from 300 to 2,000 m a.s.l. Bromeliaceae and Orchidaceae were the most species-rich families. Forests along the windward slope of the Sierra Madre Oriental (semideciduous forest and tropical montane cloud forest) had higher species richness than forests along the leeward slope (pine-oak forest and submontane scrub). Species richness was largely determined by seasonality and, to a lesser degree, by forest structure, whereas abundance was mainly determined by host tree size. Variation in VEAs composition was largely explained by climatic variables, whereas forest structure was not as important. VEAs differed among forest types and slopes in terms of taxonomic and functional composition. For example, certain bromeliad indicator species reflected differences between slopes. Although within-tree epiphytic species richness (alpha diversity) was low in this transition zone relative to other habitats, species turnover among forest types (beta diversity) was high. These findings suggest that each forest type makes a unique and important contribution to epiphytic diversity in this transition zone.
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Ramírez, Beatriz H., Adriaan J. Teuling, Laurens Ganzeveld, Zita Hegger e Rik Leemans. "Tropical Montane Cloud Forests: Hydrometeorological variability in three neighbouring catchments with different forest cover". Journal of Hydrology 552 (settembre 2017): 151–67. http://dx.doi.org/10.1016/j.jhydrol.2017.06.023.
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40
Domínguez-Eusebio, Carlo A., Enrique Alarcón, Oscar L. Briones, María del Rosario Pineda-López e Yareni Perroni. "Surface energy exchange: Urban and rural forest comparison in a tropical montane cloud forest". Urban Forestry & Urban Greening 41 (maggio 2019): 201–10. http://dx.doi.org/10.1016/j.ufug.2019.03.018.
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41
Martin, S. T., P. Artaxo, L. Machado, A. O. Manzi, R. A. F. Souza, C. Schumacher, J. Wang et al. "The Green Ocean Amazon Experiment (GoAmazon2014/5) Observes Pollution Affecting Gases, Aerosols, Clouds, and Rainfall over the Rain Forest". Bulletin of the American Meteorological Society 98, n. 5 (1 maggio 2017): 981–97. http://dx.doi.org/10.1175/bams-d-15-00221.1.
Testo completoAbstract (sommario):
Abstract The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across 2 years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied temperate regions of Earth. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the United States, employed an unparalleled suite of measurements at nine ground sites and on board two aircraft to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Herein, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.
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del Castillo, R. F., e M. A. Pérez Ríos. "Changes in seed rain during secondary succession in a tropical montane cloud forest region in Oaxaca, Mexico". Journal of Tropical Ecology 24, n. 4 (luglio 2008): 433–44. http://dx.doi.org/10.1017/s0266467408005142.
Testo completoAbstract (sommario):
AbstractSeed dispersal is the first stage of colonization, and potentially affects recruitment. This process deserves more attention in tropical montane cloud forests (TMCF), since secondary succession is common owing to episodic disturbances. We studied annual seed rain in 10 nearby forest stands, ≈7 to ≈100 y following shifting agriculture, and one primary forest stand in southern Mexico to test the hypothesis that seed rain is limited at the scale of neighbouring fragments and that such limitation differs among species with different dispersal modes and successional origin. Annual seed rain was heterogeneous among forest fragments probably due to the prevalence of local seed dispersal, differences in stand age and the proportion of zoochory, and may help explain the patchy distribution of species observed in TMCF. Seed rain abundance and species diversity per unit trap area increased with the age of the stand. Biotically dispersed seeds increased towards older stands relative to abiotically dispersed seeds. Late-successional seeds were rarer in early successional stands than pioneer seeds in late-successional stands, suggesting that long-distance dispersal is generally more common for pioneer plants. Seed dispersal appears to constrain forest regeneration and to influence fragment species composition as a function of the distance from the source forests.
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Horwath, Aline B., Jessica Royles, Richard Tito, José A. Gudiño, Noris Salazar Allen, William Farfan-Rios, Joshua M. Rapp et al. "Bryophyte stable isotope composition, diversity and biomass define tropical montane cloud forest extent". Proceedings of the Royal Society B: Biological Sciences 286, n. 1895 (23 gennaio 2019): 20182284. http://dx.doi.org/10.1098/rspb.2018.2284.
Testo completoAbstract (sommario):
Liverworts and mosses are a major component of the epiphyte flora of tropical montane forest ecosystems. Canopy access was used to analyse the distribution and vertical stratification of bryophyte epiphytes within tree crowns at nine forest sites across a 3400 m elevational gradient in Peru, from the Amazonian basin to the high Andes. The stable isotope compositions of bryophyte organic material ( 13 C/ 12 C and 18 O/ 16 O) are associated with surface water diffusive limitations and, along with C/N content, provide a generic index for the extent of cloud immersion. From lowland to cloud forest δ 13 C increased from −33‰ to −27‰, while δ 18 O increased from 16.3‰ to 18.0‰. Epiphytic bryophyte and associated canopy soil biomass in the cloud immersion zone was estimated at up to 45 t dry mass ha −1 , and overall water holding capacity was equivalent to a 20 mm precipitation event. The study emphasizes the importance of diverse bryophyte communities in sequestering carbon in threatened habitats, with stable isotope analysis allowing future elevational shifts in the cloud base associated with changes in climate to be tracked.
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Vásquez-Cruz, Víctor, Luis Canseco-Márquez e Arleth Reynoso-Martínez. "Distributional and natural history notes for Bromeliohyla dendroscarta (Anura: Hylidae) in Veracruz, Mexico". Phyllomedusa: Journal of Herpetology 18, n. 1 (18 giugno 2019): 27–36. http://dx.doi.org/10.11606/issn.2316-9079.v18i1p27-36.
Testo completoAbstract (sommario):
Distributional and natural history notes for Bromeliohyla dendroscarta (Anura: Hylidae) in Veracruz, Mexico. Two new locality records are reported for the critically endangered hylid frog, Bromeliohyla dendroscarta, in Veracruz, Mexico. The frogs were found in semideciduous tropical forest, an ecotone of semideciduous tropical forest and mountain cloud forest, and an agricultural mosaic; none of these habitats has been documented previously for this species. Information is provided on larval feeding habits, duration of larval development under natural conditions and external morphology of tadpoles.
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Rodríguez-Romero, Alexis, Axel Rico-Sánchez, Erick Mendoza-Martínez, Andrea Gómez-Ruiz, Jacinto Sedeño-Díaz e Eugenia López-López. "Impact of Changes of Land Use on Water Quality, from Tropical Forest to Anthropogenic Occupation: A Multivariate Approach". Water 10, n. 11 (26 ottobre 2018): 1518. http://dx.doi.org/10.3390/w10111518.
Testo completoAbstract (sommario):
Worldwide, it is acknowledged that changes of land use influence water quality; however, in tropical forests, the relationship between land use and water quality is still poorly understood. This study assessed spatial and seasonal variations in water quality, and the relationship between water quality and changes of land use in the Bobos-Nautla River, whose upper course runs across a patch of a tropical cloud forest. Spatial and seasonal variations in water quality and land use were assessed with multivariate tools. A cluster analysis, as well as a Principal Component Analysis (PCA-3D), identified three groups of sites: (1) an upper portion, which showed the best water quality and the broadest natural vegetation coverage; (2) a middle course, with high nitrogen and phosphorus concentrations associated with extensive agricultural uses; and (3) a lower course, characterized by the highest levels of total and fecal coliforms, as well as ammonia nitrogen, associated with the highest percentage of urbanization and human settlements. Our findings demonstrate the impact of changes of land use on water quality of rivers running through cloud forests in tropical zones, which are currently endangered ecosystems.
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Raymundo, Tania, e Ricardo Valenzuela. "Smardaea isoldae sp. nov. from a tropical cloud forest in Mexico". Mycotaxon 136, n. 1 (9 aprile 2021): 97–106. http://dx.doi.org/10.5248/136.97.
Testo completoAbstract (sommario):
Smardaea isoldae is described from Sierra Madre Oriental, Hidalgo State, Mexico. The new species is distinguished by its olivaceous coloration, habit on dead wood, and tropical cloud forest habitat. The holotype is deposited in ENCB Herbarium. A key to Smardaea species is presented.
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CHÁZARO-BASÁÑEZ, MIGUEL, e ANTONIO FRANCISCO-GUTIÉRREZ. "Eugenia naraveana (Myrtaceae), a new species from Cofre de Perote volcano slopes in Veracruz, México". Phytotaxa 286, n. 4 (5 dicembre 2016): 291. http://dx.doi.org/10.11646/phytotaxa.286.4.8.
Testo completoAbstract (sommario):
The new species Eugenia naraveana is described and illustrated here. It is only known at the windward slopes of Cofre de Perote volcano, and it grows in the upper tropical montane cloud forest. Its closest relatives are Eugenia sotoesparzae and Eugenia mexicana, but they differ from the new species because they grow in tropical perennial forests and coastal dunes, in addition to the differences in their morphological structures. This new species breaks the typical altitude range of Eugenia in Veracruz, Mexico, being registered above 2,100 up to 2,600 meters.
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Neba, Ndenecho Emmanuel. "Degradation of useful plants in Oku tropical montane cloud forest, Cameroon". International Journal of Biodiversity Science & Management 2, n. 2 (giugno 2006): 73–86. http://dx.doi.org/10.1080/17451590609618100.
Testo completo
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Alvarado-Barrientos, M. Susana, Friso Holwerda, Daniel R. Geissert, Lyssette E. Muñoz-Villers, Sybil G. Gotsch, Heidi Asbjornsen e Todd E. Dawson. "Nighttime transpiration in a seasonally dry tropical montane cloud forest environment". Trees 29, n. 1 (2 novembre 2014): 259–74. http://dx.doi.org/10.1007/s00468-014-1111-1.
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Mitchard, E. T. A., S. S. Saatchi, L. J. T. White, K. A. Abernethy, K. J. Jeffery, S. L. Lewis, M. Collins et al. "Mapping tropical forest biomass with radar and spaceborne LiDAR: overcoming problems of high biomass and persistent cloud". Biogeosciences Discussions 8, n. 4 (29 agosto 2011): 8781–815. http://dx.doi.org/10.5194/bgd-8-8781-2011.
Testo completoAbstract (sommario):
Abstract. Spatially-explicit maps of aboveground biomass are essential for calculating the losses and gains in forest carbon at a regional to national level. The production of such maps across wide areas will become increasingly necessary as international efforts to protect primary forests, such as the REDD+ (Reducing Emissions from Deforestation and forest Degradation) mechanism, come into effect, alongside their use for management and research more generally. However, mapping biomass over high-biomass tropical forest is challenging as (1) direct regressions with optical and radar data saturate, (2) much of the tropics is persistently cloud-covered, reducing the availability of optical data, (3) many regions include steep topography, making the use of radar data complex, (4) while LiDAR data does not suffer from saturation, expensive aircraft-derived data are necessary for complete coverage. We present a solution to the problems, using a combination of terrain-corrected L-band radar data (ALOS PALSAR), spaceborne LiDAR data (ICESat GLAS) and ground-based data. We map Gabon's Lopé National Park (5000 km2) because it includes a range of vegetation types from savanna to closed-canopy tropical forest, is topographically complex, has no recent cloud-free high-resolution optical data, and the dense forest is above the saturation point for radar. Our 100 m resolution biomass map is derived from fusing spaceborne LiDAR (7142 ICESat GLAS footprints), 96 ground-based plots (average size 0.8 ha) and an unsupervised classification of terrain-corrected ALOS PALSAR radar data, from which we derive the aboveground biomass stocks of the park to be 78 Tg C (173 Mg C ha−1). This value is consistent with our field data average of 181 Mg C ha−1, from the field plots measured in 2009 covering a total of 78 ha, and which are independent as they were not used for the GLAS-biomass estimation. We estimate an uncertainty of ± 25 % on our carbon stock value for the park. This error term includes uncertainties resulting from the use of a generic tropical allometric equation, the use of GLAS data to estimate Lorey's height, and the necessity of separating the landscape into distinct classes. As there is currently no spaceborne LiDAR satellite in operation (GLAS data is available for 2003–2007 only), this methodology is not suitable for change-detection. This research underlines the need for new satellite LiDAR data to provide the potential for biomass-change estimates, although this need will not be met before 2015.