scholarly journals Asymmetric effects of environmental filtering on the assembly of tropical bird communities along a moisture gradient

2018 ◽  
Author(s):  
Juan Pablo Gomez ◽  
Scott Robinson ◽  
Jose Miguel Ponciano
Keyword(s):  
Positive Relationship ◽  
Local Community ◽  
Climatic Factors ◽  
Bird Species ◽  
Bird Communities ◽  
Dry Forest ◽  
Dry Forests ◽  
Rainfall Gradient ◽  
Local Conditions ◽  
Wet Forests

AbstractThe species-sorting hypothesis (SSH) states that environmental factors influence local community assembly of metacommunities by selecting for species that are well adapted to the specific conditions of each site. Along environmental gradients, the strength of selection against individuals that are marginally adapted to the local conditions increases towards the extremes of the environment where the climate becomes harsh. In rainfall gradients, the strength of selection by the environment has been proposed to decrease with rainfall. Under this scenario SSH would predict that immigration of individuals from the metacommunity should be restricted into the dry end of the gradient creating a positive relationship between immigration and rainfall. However, if the selection is strong in both ends of the gradient, the restriction should be expected to be in both directions such that the ends behave as independent metacommunities even in the absence of geographical barriers. In this study we used models based on neutral theory to evaluate if SSH can explain the distribution of bird species along a steep rainfall gradient in Colombia. We found a strong positive relationship between immigration rates and precipitation suggesting that the dry forests impose stronger challenges for marginally adapted bird populations. However, a two-metacommunity model separating dry and wet forests was a better fit to the observed data, suggesting that both extremes impose strong selection against immigrants. The switch from the dry forest to the wet forest metacommunities occurred abruptly over a short geographic distance in the absence of any apparent geographic barrier; this apparent threshold occurs where the forest becomes mostly evergreen. The relative number of rare species in dry forest was lower than in wet forests suggesting that the selection against marginally adapted populations is stronger in the dry forests. Overall, our analyses are consistent with SSH at the regional scales, but the rarity analysis suggests that the mechanisms at the local scales are substantially different. Based on these results, we hypothesize that abiotic (climatic) factors limit immigration into dry forest communities and whereas biotic factors such as competition and predation may limit immigration into bird communities in the wet forest.

scholarly journals Using birds to set conservation priorities for Pantanal wetland forests, Brazil

2011 ◽  
Vol 22 (2) ◽  
pp. 155-169 ◽  
Author(s):  
JOÃO BATISTA DE PINHO ◽  
MIGUEL ÂNGELO MARINI
Keyword(s):  
Bird Species ◽  
Dry Forest ◽  
Evergreen Forest ◽  
Conservation Priorities ◽  
Forest Types ◽  
Dry Forests ◽  
Point Counts ◽  
Evergreen Forests ◽  
Local Species Richness ◽  
Bird Richness

SummaryThe Pantanal of Brazil, one of the largest wetlands in the world, is suffering severe threats, such as forest and grassland clearance on the surrounding plateau, conversion of forests and savannas for cattle ranching and effects of large development projects. We used richness, abundance and composition of bird species in four forest types to propose conservation priorities for the northern Pantanal. Birds from 11 sites (a total of 41 points) were sampled through point counts and mist-netting. In total 215 species were recorded in the forests. Two evergreen forest types (cambarazal and landi) had higher estimates of bird richness and abundance than two dry forest types (carvoeiro and cordilheira). The evergreen forests also had more species exclusive to them and were more similar to each other than the dry forests. Selection of forests to be conserved in the northern Pantanal should give priority to evergreen forests and secondarily to dry forests. Cambarazal should be the first forests to be conserved. If the Pantanal inundation cycle is altered by the construction of hydroelectric dams or the Paraguay-Paraná waterway, cambarazal and landi may no longer become flooded, decreasing local species richness. Before our recommendations are considered for conservation and management decisions, more studies on other groups of organisms should also be taken into consideration, and similar studies should be conducted in other regions of the Pantanal. Conservation of Pantanal forest birds depends on a deeper understanding of their use of several habitats, stronger protection of the forests with higher diversity, and public policies that guarantee the long term maintenance of natural flooding cycles.

scholarly journals The effects of forest-savanna-grassland gradients on bird communities of Chiquitano Dry Forests domain, in western Brazil

2016 ◽  
Vol 88 (3 suppl) ◽  
pp. 1755-1767 ◽  
Author(s):  
MAURICIO N. GODOI ◽  
EDIVALDO O. DE SOUZA
Keyword(s):  
Quantitative Methods ◽  
Habitat Type ◽  
Bird Species ◽  
Bird Communities ◽  
Vegetation Types ◽  
Dry Forests ◽  
Bird Abundance ◽  
Qualitative And Quantitative Methods ◽  
Composition And Structure ◽  
Bird Composition

ABSTRACT Different vegetation types are distributed in mountains according to altitude, topography and soil. The composition and structure of bird communities in these areas can change in relation to the vegetation gradient, with particular communities occupying each habitat type. In this study we present the changes in composition, species richness and bird abundance over the gradient of forests, savannas and altitudinal grasslands of Maciço do Urucum, a mountainous region located in the Chiquitano Dry Forests domain in western Brazil. We recorded 165 bird species through qualitative and quantitative methods. Forested savannas, riparian forests and submontane forests presented the highest richness and abundance of birds, while arboreal savannas and altitudinal grasslands had intermediate and low values, respectively. The bird composition was similar between riparian and submontane forests, while other vegetation types present more dissimilar bird communities. Our results show differences in composition, richness and bird abundance among the vegetation types present at Maciço do Urucum, and highlight an important function of vegetation gradients for the conservation of bird communities in mountains. Additionally, this is the first study of the bird communities in the Brazilian Chiquitano Dry Forests, an important domain in the west of Brazil which has been poorly studied.

scholarly journals Erosion of tropical bird diversity over a century is influenced by abundance, diet and subtle climatic tolerances

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jenna R. Curtis ◽  
W. Douglas Robinson ◽  
Ghislain Rompré ◽  
Randall P. Moore ◽  
Bruce McCune
Keyword(s):  
Human Disturbance ◽  
Bird Species ◽  
Bird Communities ◽  
Habitat Characteristics ◽  
Barro Colorado Island ◽  
Bird Diversity ◽  
Species Assemblage ◽  
Forest Fragment ◽  
Rainfall Gradient ◽  
Dietary Preferences

AbstractHuman alteration of landscapes leads to attrition of biodiversity. Recommendations for maximizing retention of species richness typically focus on protection and preservation of large habitat patches. Despite a century of protection from human disturbance, 27% of the 228 bird species initially detected on Barro Colorado Island (BCI), Panama, a large hilltop forest fragment isolated by waters of Gatun Lake, are now absent. Lost species were more likely to be initially uncommon and terrestrial insectivores. Analyses of the regional avifauna, exhaustively inventoried and mapped across 24 subregions, identified strong geographical discontinuities in species distributions associated with a steep transisthmian rainfall gradient. Having lost mostly species preferring humid forests, the BCI species assemblage continues to shift from one originally typical of wetter forests toward one now resembling bird communities in drier forests. Even when habitat remnants are large and protected for 100 years, altered habitat characteristics resulting from isolation produce non-random loss of species linked with their commonness, dietary preferences and subtle climatic sensitivities.

PUBLIC HEALTH, NURSING AND MEDICAL SOCIAL WORK

PEDIATRICS ◽  
1952 ◽  
Vol 9 (5) ◽  
pp. 651-655
Keyword(s):  
Public Health ◽  
Rural Areas ◽  
Local Community ◽  
Climatic Factors ◽  
Dental Health ◽  
Economic Feasibility ◽  
Health It ◽  
Local Conditions ◽  
Dental Profession ◽  
Health Nursing

" . . . In view of these considerations, your Committee recommends that any community which includes a child population of sufficient size, and which obtains its water supply from sources which are free from or are extremely low in fluorides, should consider the practicability and economic feasibility of adjusting the concentration to optimal levels. This adjustment should be in accord with climatic factors and a constant chemical control should be maintained. With proper safeguards, this procedure appears to be harmless. However, it should be conducted under expert dental and engineering supervision by the state board of health. It should not be undertaken unless this can be provided. How much reduction in the prevalence of caries will actually be realized in a particular community will vary according to local conditions. The procedure will supplement but not supplant other dental health measures. About one half of the population of this country is living in small villages and rural areas and will not benefit by fluoridation of public water supplies. Other provisions for preventing dental caries in this fraction of the population should be continued and developed." Support of the policy of fluoridation has come officially from the U. S. Public Health Service, the Association of State and Territorial Health Officers, the American Public Health Association, the American Dental Association and more recently the American Medical Association. It is to the distinct credit of the dental profession and both national and local dental societies that they have been in the forefront of local community efforts to further a preventive technique which should have the effect of reducing the amount of reparative dentistry needed.

Ungulate biomass across a rainfall gradient: a comparison of data from neotropical and palaeotropical forests and local analyses in Mexico

2009 ◽  
Vol 26 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Salvador Mandujano ◽  
Eduardo J. Naranjo
Keyword(s):  
Local Level ◽  
Tropical Dry Forest ◽  
Biosphere Reserve ◽  
Dry Forest ◽  
Dry Forests ◽  
Rainfall Gradient ◽  
Neotropical Forests ◽  
Data Set ◽  
Precipitation Regimes ◽  
Polynomial Models

Abstract:Using a data set from 36 studies, we evaluated variation in ungulate biomass across a rainfall gradient using polynomial models, aiming to: (1) compare neotropical and palaeotropical dry and wet forests as well as African savannas; and (2) evaluate the usefulness of polynomial models to predict ungulate biomass at neotropical sites using data from a dry forest (Chamela-Cuixmala Biosphere Reserve, CCBR) and a wet forest (Montes Azules Biosphere Reserve, MABR) in Mexico. Our results showed that an overestimation of expected ungulate biomass can be obtained for some tropical forests if data from African savannas are included in the model. This overestimation was particularly high for predicted ungulate biomass in neotropical dry forests. These ecosystems sustain different ungulate biomass values even when rainfall is similar. This was particularly true for some tropical dry forests and savannas. Rainfall predicted the expected ungulate biomass in neotropical ecosystems relative to that of palaeotropical ones under similar precipitation regimes, but did not correctly predict the observed ungulate biomass at local level if data outside the Neotropics are included in the model. This was more evident when we compared observed biomass against predicted biomass in the tropical dry forest of CCBR, while some polynomial models successfully predicted the observed biomass for the tropical wet forest of MABR. Factors such as Pleistocene extinctions and the absence of large, native grazers (i.e. Bovidae) that have kept ungulate richness and standing biomass relatively low in neotropical forests should be accounted for when comparing data sets from different regions.

scholarly journals Fire resistance in a Caribbean dry forest: inferences from the allometry of bark thickness

2014 ◽  
Vol 30 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Brett T. Wolfe ◽  
Gabriel E. Saldaña Diaz ◽  
Skip J. Van Bloem
Keyword(s):  
Fire Resistance ◽  
Deciduous Forest ◽  
Dry Forest ◽  
Stem Diameter ◽  
Bark Thickness ◽  
Dry Forests ◽  
Seasonally Dry ◽  
Scrub Forest ◽  
The Tropics ◽  
Wet Forests

Abstract:Trees’ resistance to fire-induced mortality increases with bark thickness, which varies widely among species and generally increases with stem diameter. Because dry forests are more fire-prone than wetter forests, bark may be thicker in these forests. However, where disturbances such as hurricanes suppress stem diameter, trees may not obtain fire-resistant bark thickness. In two hurricane-prone Caribbean dry-forest types in Puerto Rico—deciduous forest and scrub forest—we measured bark thickness on 472 stems of 25 species to test whether tree species obtain bark thicknesses that confer fire resistance, whether bark is thicker in the fire-prone scrub forest than in the deciduous forest, and how bark thickness in Caribbean dry forest compares with other tropical ecosystems. Only 5% of stems within a deciduous-forest stand had bark thickness that would provide < 50% probability of top-kill during low-intensity fire. In contrast, thicker-barked trees dominated the scrub forest, suggesting that fires influenced it. Compared with trees of similar diameter in other regions of the tropics, bark in Caribbean dry forest was thinner than in savanna, similar to other seasonally dry forests, and thicker than moist-to-wet forests. Dry-forest species appear to invest more in fire-resistance than species from wetter forests. However, Caribbean dry forests remain highly vulnerable to fire because the trees rarely reach large enough diameters to be fire resistant.

Functional evenness of bird communities varies along the elevational gradient in Europe: Conservation implications

2019 ◽  
Author(s):  
Federico Morelli ◽  
Yanina
Keyword(s):  
Species Richness ◽  
Elevation Gradient ◽  
Bird Species ◽  
Elevational Gradient ◽  
Negative Association ◽  
Bird Communities ◽  
Breeding Bird ◽  
Bird Species Richness ◽  
Large Spatial Scale ◽  
Functional Evenness

ContextThe negative association between elevation and species richness is a well-recognized pattern in macro-ecology. ObjectivesThe aim of this study was to investigate changes in functional evenness of breeding bird communities along an elevation gradient in Europe. MethodsUsing the bird data from the EBCC Atlas of European Breeding Birds we estimated an index of functional evenness which can be assumed as a measure of the potential resilience of communities.ResultsOur findings confirm the existence of a negative association between elevation and bird species richness in all European eco regions. However, we also explored a novel aspect of this relationship, important for conservation: Our findings provide evidence at large spatial scale of a negative association between the functional evenness (potential community resilience) and elevation, independent of the eco region. We also found that the Natura2000 protected areas covers the territory most in need of protection, those characterized by bird communities with low potential resilience, in hilly and mountainous areas.ConclusionsThese results draw attention to European areas occupied by bird communities characterized by a potential lower capacity to respond to strong ecological changes, and, therefore, potentially more exposed to risks for conservation.

Utilisation of wild growing yams as supplementary nutrition and its impact on the dry forest ecosystem in north-western Madagascar

2004 ◽  
Vol 155 (3-4) ◽  
pp. 80-88 ◽  
Author(s):  
Klaus Ackermann
Keyword(s):  
Forest Ecosystem ◽  
Rainy Season ◽  
Secondary Forest ◽  
Local Population ◽  
Dry Forest ◽  
Dry Forests ◽  
Supplementary Food ◽  
Wild Yams ◽  
Supplementary Nutrition ◽  
North Western

Wild growing yams (Dioscorea spp.) are an important supplementary food in Madagascar, especially during periods of rice shortage in the rainy season. Yams grow in dry forests and there is a particularly high occurrence of yam tubers in recently burned, open secondary forest formations. The study found that the uncontrolled harvest of yams can contribute to the degradation of dry forests due to the high quantity of wild yams harvested by the local population and the widespread practice of intentionally burning forests to increase yams production.

scholarly journals Bird communities in a degraded forest biodiversity hotspot of East Africa

2021 ◽  
Author(s):  
Moses Mulwa ◽  
Mike Teucher ◽  
Werner Ulrich ◽  
Jan Christian Habel
Keyword(s):  
Tropical Forests ◽  
Agricultural Land ◽  
Bird Species ◽  
Bird Communities ◽  
Natural Forest ◽  
Tree Plantations ◽  
Agricultural Fields ◽  
Degraded Forest ◽  
Forest Patches ◽  
Small Forest

AbstractTropical forests suffer severe habitat destruction. Thus, tropical forests frequently consist today of only a few small remnants that are often embedded within a matrix of agricultural fields and tree plantations. Forest specialist species have experienced severe population declines under these circumstances. We studied bird communities based on census plots set up in a near-natural forest block, as well as degraded forest patches, tree plantations, and agricultural fields, across the Taita Hills in southern Kenya. We classified each bird species according its ecology and behavior. We quantified the land cover and landscape configuration around each census plot. Typical forest species were mainly observed in the near-natural forest block, and to a lower extent in degraded forest patches. Plantations were almost devoid of birds. Bird communities of small forest fragments were more similar to that of agricultural land than the near-natural forest block. Most frugivorous, insectivorous and nectarivorous birds occurred in forest habitats, while granivorous bird species dominated the bird communities of agricultural land. The surrounding landscape had a marginal impact on bird species composition at local sites. Our study showed that the preservation of near-natural cloud forest, including small forest patches, is essential for the conservation of forest-dependent species, and that plantations do not serve as surrogate habitats.

scholarly journals Can clearcuts increase bird species richness in managed forests?

2008 ◽  
Vol 54 (No. 4) ◽  
pp. 189-193
Author(s):  
M. Żmihorski
Keyword(s):  
Species Richness ◽  
Bird Species ◽  
Bird Communities ◽  
Cumulative Number ◽  
Managed Forests ◽  
Managed Forest ◽  
Bird Species Richness ◽  
Forest Interior ◽  
Transect Counts ◽  
The Difference

Clearcuts are one of the results of forest management. The aim of this study was to assess the effect of clearcuts on bird communities in a managed forest in Western Poland. I applied the method of point transect counts. 20 points were located near clearcuts (less than 100 m from the nearest clearcut) and 25 points in the forest interior. In total, 36 bird species were recorded. On average, I found 9.20 bird species at points located near clearcuts and 6.72 species at points situated in the forest interior, and the difference was significant. The cumulative number of bird species for a given number of sampling points in the vicinity of clearcuts was higher than in the forest interior. The obtained results indicate that in managed, even-aged forests the generation of clearcuts can lead to an increase in local bird species richness.

Sign in / Sign up

Export Citation Format

Share Document