scholarly journals Delayed effects of climate on vital rates lead to demographic divergence in Amazonian forest fragments

2021 ◽  
Author(s):  
Eric R Scott ◽  
Emilio Miguel Bruna ◽  
María Uriarte
Keyword(s):  
Amazon Basin ◽  
Life History Stage ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Vital Rates ◽  
Climate Data ◽  
Plant Populations ◽  
Delayed Effects ◽  
Continuous Forest ◽  
Flowering Probability

Deforestation often results in landscapes where remaining forest habitat is highly fragmented, with remnants of different sizes embedded in an often highly contrasting matrix. Local extinction of species from individual fragments is common, but the demographic mechanisms underlying these extinctions are poorly understood. It is often hypothesized that altered environmental conditions in fragments drive declines in reproduction, recruitment, or survivorship. The Amazon basin, in addition to experiencing continuing fragmentation, is warming and experiencing changes in precipitation leading to altered frequency and intensity of droughts and unusually wet periods. Whether plant populations in tropical forest fragments are particularly susceptible to extremes in precipitation remains unclear. Most studies of plants in fragments are relatively short (1-6 years), focus on a single life-history stage, and often do not compare to populations in continuous forest. Even fewer studies consider delayed effects of climate on demographic vital rates despite the importance of delayed effects in studies that consider them. Using a decade of demographic and climate data from an experimentally fragmented landscape in the Central Amazon, we assess the effects of climate on populations of an understory herb (Heliconia acuminata, Heliconiaceae). We used distributed lag non-linear models to understand the delayed effects of temperature and precipitation on survival, growth, and flowering. We detected delayed effects of climate up to 36 months. Drought two dry seasons prior to the February census decreased survival and increased flowering probability while drought in the wet season a year prior to the census decreased flowering probability and increased growth. The effects of extremes in precipitation on survival and growth were more pronounced in forest fragments compared to continuous forest. The complex delayed effects of climate and habitat fragmentation in our study point to the importance of long-term demography experiments in understanding the effects of anthropogenic change on plant populations.

Gap-crossing by Wood Thrushes (Hylocichla mustelina)in a fragmented landscape

2011 ◽  
Vol 89 (11) ◽  
pp. 1091-1097 ◽  
Author(s):  
T. MacIntosh ◽  
B.J.M. Stutchbury ◽  
M.L. Evans
Keyword(s):  
Radio Telemetry ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Hylocichla Mustelina ◽  
Continuous Forest ◽  
Migratory Songbirds ◽  
Gap Crossing ◽  
Wood Thrushes ◽  
Gap Width

We used radio-telemetry to study the movement patterns of Wood Thrushes ( Hylocichla mustelina (J.F. Gmelin, 1789)) occupying small forest fragments (<5 ha) to examine gap-crossing between fragments and edge use within fragments. We found that 82% (8/11) of males and 33% (2/6) of females made at least one foray off of its resident forest fragment and we documented a total of 26 off-fragment forays (n = 79 h tracking). Males spent, on average, 23.5% of their time off their fragment, while females were gone 12.8% of the time tracked. Most forays were >150 m in distance and foray rate to adjacent fragments declined with increasing gap width. Males on fragments spent more time off their territory (23.5%) and traveled farther (392 m) than males occupying territories within a continuous forest (4.8% and 99 m, respectively). In fragments, 10 out of 17 individuals spent >80% of their time within 20 m of the fragment edge and edge use was significantly more than expected based on the amount of edge available in each fragment. This study adds to the growing evidence for migratory songbirds that during the breeding season, forest fragmentation may increase rather than impede daily movements.

scholarly journals Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 67 ◽  
Author(s):  
Inês Silva ◽  
Ricardo Rocha ◽  
Adrià López-Baucells ◽  
Fábio Z. Farneda ◽  
Christoph F. J. Meyer
Keyword(s):  
Forest Fragmentation ◽  
Vertical Structure ◽  
Three Dimensional ◽  
Vertical Stratification ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Continuous Forest ◽  
Forest Strata ◽  
Neotropical Bats ◽  
Artibeus Lituratus

Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.

scholarly journals The persistence of ant-following birds in small amazonian forest fragments

1989 ◽  
Vol 19 (0) ◽  
pp. 249-263 ◽  
Author(s):  
Lee H. Harper
Keyword(s):  
Forest Fragments ◽  
Ant Colonies ◽  
Amazonian Forest ◽  
Army Ant ◽  
Continuous Forest ◽  
Introduced Birds ◽  
Small Forest

SUMMARYMist-net captures of army ant-following bird were monitored during the isolation of central Amazonian forest fragments of 1 ha (n = 5), 10 ha (n = 4) and 100 ha (n = 1). Post-isolation captures of the three obligate ant-following birds Dendrocinela merula, Pithys albifrons, and Gymnopithys rufigula decreased significantly in all fragments. post-isolation captures of four facultative ant-following species were not significantly different in forest fragments of 1 ha and 10 ha, although two species decreased significantly in the 100 ha fragment. Experimental introductions of obligate species into small forest fragments in the absence and presence of introduced Eciton burchelli army ant colonies resulted in significantly greater recaptures of introduced birds when active army ant colonies were present. Of the 105 birds introduced, 58 ' 55%) crossed 100-320 m od dedorested area an were recaptured in continuous forest.

scholarly journals Distribution of Atta (Hymenoptera - Formicidae) in "terra-firme" rain forest of Central Amazonia: density, species composition and preliminary results on effects of forest fragmentation

1988 ◽  
Vol 18 (3-4) ◽  
pp. 309-315 ◽  
Author(s):  
Heraldo Luís de Vasconcelos
Keyword(s):  
Species Composition ◽  
Rain Forest ◽  
Abundant Species ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Terra Firme ◽  
Atta Sexdens ◽  
Conservation Areas ◽  
Continuous Forest ◽  
Leaf Cutting

One hundred and fourteen hectares of a "terra-fiirme" rain forest 70 km north of Manaus, Amazonas, Brazil, were surveyed for leaf-cutting ant colonies (Atta spp). One half of this area was in isolated forest fragments (surrounded by pastures or second growth) of two sizes: 1 and 10 ha. The other half was in non-isolated fragments (connected to a large parch of forest) of the same sizes. Only two species occured in this forest: Atta sexdens sexdens L. and A. cepfhalotes L. The first was the most abundant species with a mean density of 0.35 colonies per ha. The mean density of A. cephalotes colonies was 0.03 per ha. The density of colonies was not significantly different between the isolated fragments and the continuous forest. Furthermore, the species composition did not change with isolation. However, pre-isolation data and long term monitoring are necessary to conclude that the isolation of a forest fragment has no effect upon Atta colonies. The non-uniform spatial distribution of Atta colonics within the "terra-firme" forest must be taken into account when selecting conservation areas in the Amazon, in order to preserve this important group of ants together with their native habitat.

scholarly journals Recover and They’ll Come: Flower Visiting Bees Benefit from the Continuous of Micro-Environments Set by Regenerating Forest Fragments

Sociobiology ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 5861
Author(s):  
Ana Isabel Sobreiro ◽  
Lucas Lopes da Silveira Peres ◽  
Jessica Amaral Henrique ◽  
Rosilda Mara Mussury ◽  
Valter Vieira Alves-Junior
Keyword(s):  
Urban Areas ◽  
Environmental Changes ◽  
Climatic Conditions ◽  
Agricultural Activity ◽  
Forest Fragments ◽  
Forest Types ◽  
Continuous Forest ◽  
Flower Visiting ◽  
Bee Communities ◽  
Forest Habitats

Forest habitats are important sources of food and nesting resources for pollinators, primarily in urban areas and landscapes with intense agricultural activity. The forest fragmentation and environmental changes occurring in these green refuges are known to impose survival challenges to pollinating bees, leading to species loss. However, it is not well known how the species of bees that visit flowers are distributed in forest micro-environments. To fill this gap, we sampled flower visiting bees in a continuous forest matrix with micro-environments of two forest types (mature and regenerating forest). We examined how the local environmental changes and climatic conditions affect the composition and uniformity of bee communities in the different micro-environments. Our results indicated that both abundance and richness were similar between forest types studied here, however climatic conditions and plant flowering patterns affect the composition of bees. Thus, our results demonstrated that the continuous micro-environments can favor floral visits and the reintegration of bee communities, and still, that this strategy can be used to minimize the impacts of environmental changes at local scales.

Forest corridors facilitate movement of tropical forest birds after experimental translocations in a fragmented Neotropical landscape in Mexico

2011 ◽  
Vol 27 (5) ◽  
pp. 547-556 ◽  
Author(s):  
Ana Ibarra-Macias ◽  
W. Douglas Robinson ◽  
Michael S. Gaines
Keyword(s):  
Forest Birds ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Forest Dependence ◽  
Capture Site ◽  
Forest Corridors ◽  
Capture Recapture ◽  
Species Characteristics ◽  
Species Groups ◽  
Positive Effect

Abstract:We evaluated effects of corridors between forest fragments surrounded by pastures in tropical Mexico. We used experimental translocations and capture–recapture data to measure the proportion of birds returning and time to return after translocation between connected and unconnected patches (five replicates for each treatment). Depending on each species’ degree of forest dependence (forest-restricted and forest-unrestricted species), we assigned birds to two groups to evaluate influence of species characteristics on effects of corridors on movement. Birds translocated between connected patches (n = 75) were seven times more likely to be recaptured in their original capture site when compared with birds translocated between unconnected patches (n = 109). Effects differed among the two species groups. In the presence of corridors, 46% of forest-unrestricted birds returned to the capture site while only 5% returned between unconnected patches. Forest-restricted birds showed similar results, but were only twice as likely to return to a connected capture site. Birds translocated between unconnected patches took longer to return than birds translocated between connected patches. The strong positive effect of corridors on movement, even for forest-unrestricted species, suggests that forested corridors facilitate bird movement and help maintain connectivity even in this highly fragmented landscape.

Effects of forest fragmentation on neotropical fauna: current research and data availability

1995 ◽  
Vol 3 (2) ◽  
pp. 191-211 ◽  
Author(s):  
Holly L. Offerman ◽  
Virginia H. Dale ◽  
Scott M. Pearson ◽  
Robert V. O'Neill ◽  
Richard O. Bierregaard Jr.
Keyword(s):  
Forest Fragmentation ◽  
Amazon Basin ◽  
Data Availability ◽  
Forest Fragments ◽  
Forest Patches ◽  
Neotropical Fauna ◽  
Using Data ◽  
Spatially Explicit Data ◽  
Biological Dynamics

Tropical deforestation often produces landscapes characterized by isolated patches of forest habitat surrounded by pasture, agriculture, or regrowth vegetation. Both the size and the distribution of these forest patches may influence the long-term persistence of faunal species. There is, therefore, a pressing need to understand faunal responses to patterns of forest fragmentation in tropical systems. The Biological Dynamics of Forest Fragments Project (BDFFP) provides a wealth of autecological information and spatially explicit data describing habitat use and movement of fauna between Amazonian forest fragments. Using data from the BDFFP and other studies in the Amazon Basin, this paper reviews the information available on tropical insects, frogs, birds, primates, and other mammals that can be used to identify and classify species most at risk for extirpation in fragmented forests.Key words: Amazonia, habitat fragmentation, rainforest, fauna, Biological Dynamics of Forest Fragmentation Project.

scholarly journals Testing the Risk-Disturbance Hypothesis in a Fragmented Landscape: Nonlinear Responses of House Sparrows to Humans

The Condor ◽  
2003 ◽  
Vol 105 (2) ◽  
pp. 316-326 ◽  
Author(s):  
Esteban Fernández-Juricic ◽  
Angel Sallent ◽  
Ruben Sanz ◽  
Iñaki RodrÍguez-Prieto
Keyword(s):  
Resource Use ◽  
Urban Landscape ◽  
Passer Domesticus ◽  
Mechanistic Explanation ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
House Sparrows ◽  
Trade Off ◽  
Nonlinear Responses ◽  
Consumption Rates

Abstract We used House Sparrows (Passer domesticus) as a model species to assess responses to different levels of human visitation in a fragmented urban landscape. Regionally, we analyzed linear and nonlinear variation in breeding densities in relation to observed pedestrian rates in forest fragments. Locally, we tested experimentally the resource-use–disturbance trade-off hypothesis, which suggests that an increase in the frequency of human visitation decreases the frequency of resource use by an animal, assuming that individuals react to humans as if they were potential predators, and that responses depend upon the probability of visually detecting humans. Breeding densities peaked at intermediate pedestrian rates in two consecutive years. Consumption rates of artificial food within fragments were higher at intermediate pedestrian rates, which may indicate that this species uses people as cues to find food. Consumption rates decreased at high pedestrian rates as a result of low tolerance to people and a reduction in the time devoted to foraging. Our results imply a balance between attraction to and avoidance of humans to account for these nonlinear responses, and that the resource-use–disturbance trade-off hypothesis can be a useful mechanistic explanation for understanding the responses to humans of species that may receive a direct or indirect benefit from human presence. Probando la Hipótesis del Riesgo-Perturbación en un Paisaje Fragmentado: Respuestas No Lineales de Passer domesticus hacia Humanos Resumen. Se escogió a Passer domesticus como especie modelo para analizar su respuesta a distintos niveles de perturbación humana en un ambiente urbano fragmentado. Regionalmente, se analizaron las variaciones lineales y no-lineales en las densidades reproductivas con relación a la tasa observada de visitantes a fragmentos forestales. Localmente, se comprobó experimentalmente la hipótesis del balance entre el uso del recurso y perturbación, la cual analiza la relación entre la frecuencia de visita y la frecuencia de uso del recurso, suponiendo que los animales reaccionan hacia los humanos como si fuesen depredadores, y que las respuestas dependen de las probabilidades de detección de humanos. Las densidades reproductivas en dos años consecutivos fueron más elevadas con tasas de visita intermedias. Las tasas de consumo dentro de fragmentos mostraron un pico cuando la frecuencia de visita fue intermedia, lo que sugiere que esta especie utiliza a los humanos como indicadores de alimento; pero la tasa de consumo disminuyó con frecuencias de visita mas elevadas como resultado de la baja tolerancia hacia humanos y la reducción del tiempo dedicado a la alimentación. Nuestros resultados indican que un balance entre atracción y repulsión hacia humanos está involucrado en las respuestas no lineales y que la hipótesis del balance entre el uso del recurso y el disturbio puede ser una explicación apropiada para comprender las respuestas de especies que reciben un beneficio directo o indirecto de la presencia humana.

scholarly journals Primate populations in continuous forest and forest fragments in Central Amazonia

1988 ◽  
Vol 18 (3-4) ◽  
pp. 291-307 ◽  
Author(s):  
Anthony B. Rylands ◽  
Alexine Keuroghlian
Keyword(s):  
Food Sources ◽  
Primate Species ◽  
Forest Fragments ◽  
The Past ◽  
Pithecia Pithecia ◽  
Ateles Paniscus ◽  
Continuous Forest ◽  
Second Growth ◽  
Central Amazonia ◽  
One Year

Population densities of six primate species (Saguinus midas, Pithecia pithecia, Cebus apella, Chiropotes satanas, Alouatta seniculus and Ateles paniscus) were estimated in continuous forest and in isolated reserves (one of 100 ha and four of 10 ha). Saguinusdensities in the continuous forest were found to be low, probably due to the lack of edge habitat and second growth favoured by them; Pithecia, Cebus and Ateles populations are also low, possibly because of more widely distributed and/or less abundant food sources than is true for other Amazonian regions, although hunting in the past, particularly of Ateles may also be a contributing factor; and Chiropotes and Alouatta densities were found to be similar to those observed in other areas of Amazonas forests. Ateles and Chiropotes, which occupy ranges on the order of three km2 were excluded from the 100-ka reserve at the time of its isolation. Unfortunately populations were not known prior to isolation of this reserve but during isolation there remained four groups of Saguinus, two Pitheciagroups, one Cebus groups and five Alouatta groups. One Saguinus group disappeared two months later, and one year post-isolation the Cebus group also left the reserve. Single Alouatta groups survive in the isolated 10-ha reserves. Saguinus, present in the four 10-ha reserves following isolation, have disappeared from two of them. One 10-ha reserve retains a group of Pithecia.

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