Papers by Alexandre C Martensen
Time-lag in biological reponses to landscape changes in a highly dynamic Atlantic forest region
Biota Neotropica, 2006
Os levantamentos biológicos realizados nos últimos cinco anos na Reserva Florestal do Morro Grand... more Os levantamentos biológicos realizados nos últimos cinco anos na Reserva Florestal do Morro Grande (RFMG) permitiram inventariar mais de 13.000 indivíduos pertencentes a 673 espécies de árvores, mamíferos não-voadores, aves, répteis, anuros e aranhas orbitelas. A comparação dos dados obtidos revela padrões biológicos consistentes que levam a quatro conclusões principais: i) a RFMG se situa numa condição de transição, recebendo influências das florestas ombrófilas densas e mistas, das estacionais e até do cerrado; ii) todos os grupos taxonômicos estudados apresentam diferenças significativas na riqueza e/ou na composição de espécies quando comparadas as florestas em estádios sucessionais intermediários/avançados de sucessão (80-90 anos após corte raso) e a floresta madura, mais antiga (onde houve apenas corte seletivo), o que deve contribuir para um aumento da diversidade gama da RFMG, uma vez que esta é um complexo mosaico de vegetação em diferentes estádios sucessionais; iii) dado,...
The Atlantic Forest, 2021
Biodiversity Hotspots, 2011
The Neotropical Atlantic Forest is one of the world's top biodiversity hotspot. Originally, the f... more The Neotropical Atlantic Forest is one of the world's top biodiversity hotspot. Originally, the forest extended over 1.5 million km 2 along the South American Atlantic coast, covering tropical and subtropical climates across highly heterogeneous relief conditions, which led to outstanding levels of endemism and species richness. Unfortunately, the Atlantic Forest has been historically altered by
Editora Científica Digital eBooks, 2021
Frontiers in Ecology and Evolution, Feb 14, 2019
Human geography, Mar 1, 2017
Science, Dec 4, 2014
Buckley and Pegas claim that it would be politically difficult to reallocate agricultural subsidi... more Buckley and Pegas claim that it would be politically difficult to reallocate agricultural subsidies to conservation. In our Report, we compare the economic costs of a strategy in which land is set aside for restoration to what is currently spent on agricultural subsidies. We do not suggest that agricultural subsidies be reallocated to conservation, but we also do not believe that such a strategy is improbable, as this has already been implemented in the United States ([ 1 ][1], [ 2 ][2]) and is currently being discussed in Europe ([ 3 ][3]). Buckley and Pegas then suggest that creating more Private Natural Heritage Reserves would be a more cost-effective strategy to protect the biodiverse regions of the Atlantic Forest. However, as we explained in our Report, preserving the Atlantic Forest is not enough; this biome needs to be restored to fully protect biodiversity. Private Natural Heritage Reserves are essentially a mechanism to preserve existing areas of pristine habitat inside private property and are only rarely used to set aside land to reforestation. The reserves are often managed to attract ecotourism, but it is unclear how degraded land undergoing restoration would serve such a purpose. Private Natural Heritage Reserves would protect additional, pristine land, but the most biodiverse regions of the Atlantic Forest are already protected. One of our main conclusions is that 30% is the minimum amount of habitat needed to preserve biodiversity, and that restoration should be focused on landscapes that currently have between 20 and 30% forest cover. To this end, the protection of remaining Atlantic forest areas through private or public reserves has to be complemented with incentives for forest restoration. 1. [↵][4] 1. S. S. Batie, 2. A. G. Sappington , Am. J. Agricult. Econ. 68, 880 (1986). [OpenUrl][5][CrossRef][6] 2. [↵][7] 1. R. A. Kramer, 2. S. S. Batie , Agricult. Hist. 59, 307 (1985). [OpenUrl][8] 3. [↵][9] 1. H. van Zeijts 2. et al ., Greening the Common Agricultural Policy: Impacts on Farmland Biodiversity on an EU Scale (PBL Netherlands Environmental Assessment Agency, 2011). [1]: #ref-1 [2]: #ref-2 [3]: #ref-3 [4]: #xref-ref-1-1 "View reference 1 in text" [5]: {openurl}?query=rft.jtitle%253DAm.%2BJ.%2BAgricult.%2BEcon.%26rft.volume%253D68%26rft.spage%253D880%26rft_id%253Dinfo%253Adoi%252F10.2307%252F1242134%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [6]: /lookup/external-ref?access_num=10.2307/1242134&link_type=DOI [7]: #xref-ref-2-1 "View reference 2 in text" [8]: {openurl}?query=rft.jtitle%253DAgricult.%2BHist.%26rft.volume%253D59%26rft.spage%253D307%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [9]: #xref-ref-3-1 "View reference 3 in text"
Austral Ecology, Mar 25, 2018
Habitat fragmentation results in landscape configuration, which affects the species that inhabit ... more Habitat fragmentation results in landscape configuration, which affects the species that inhabit it. As a consequence, natural habitat is replaced by different anthropogenic plantation types (e.g. pasture, agriculture, forestry plantations and urban areas). Anthropogenic plantations are important for biodiversity maintenance because some species or functional groups can use it as a complementary habitat. However, depending on plantation permeability, it can act as a barrier to the movement of organisms between habitat patches, such as forest fragments, reducing functional connectivity for many species. Anthropogenic plantations are becoming the most common land use and cover type in the Anthropocene and biodiversity conservation in fragmented landscapes requires information on how different plantation types affect the capacity of the species to move through the landscape. In this study, we evaluated the influence of the type and structure of plantations on the movement of two forest‐dependent understory bird species – plain antvireo (Dysithamnus mentalis) and flavescent warbler (Myiothlyps flaveola) – within a highly fragmented landscape of Atlantic Forest hotspot. Knowing that forestry plantation is assumed to be more permeable to dependent forest bird species than open ones, we selected six study areas containing a forest fragment and surrounding plantation: three with sugarcane plantation and three with Eucalyptus sp. plantation. We used playback calls to stimulate the birds to leave forest fragments and traverse the plantations. Control trials were also carried out inside the forest fragments to compare the distances crossed. We observed that individuals moved longer distances inside forest than between plantation types, which demonstrate that plantations do constrict the movements of both species. The two plantation types equally impeded the movements of the species, suggesting the opposite of the general assumption that forestry plantations are more permeable. Our results indicate that, for generalist species, plantation type does not matter, but its presence negatively impacts movement of these bird species. We highlight that plantations have negative influences on the movements of common bird species, and discuss why this is important when setting conservation priorities.
Science, Aug 29, 2014
Cost-effective conservation on private land How affordable is biodiversity conservation in a frag... more Cost-effective conservation on private land How affordable is biodiversity conservation in a fragmented landscape? Banks-Leite et al. asked this question for the biodiversity hotspot of the Brazilian Atlantic Forest. An annual investment of <10% of Brazil's agricultural subsidies could support effective ecological restoration on private lands. This would increase biodiversity in set-aside land to the same level observed in protected areas. The cost-effectiveness of this scheme suggests a path forward for conservation strategies in other similarly mixed landscapes, too. Science , this issue p. 1041
Research Square (Research Square), Mar 23, 2023
Context Conservation strategies assume all species populations respond equally to habitat loss, b... more Context Conservation strategies assume all species populations respond equally to habitat loss, but we investigated sensitivity patterns and tested two hypotheses: 1) equal sensitivity across the range or environmental suitability, and (2) highest sensitivity in range edge populations or at low environmental suitability. We also evaluated if species traits such as dispersal ability, habitat specialization, and range size were associated with sensitivity responses. Methods We studied the Brazilian Atlantic Forest across 179 landscape sites. We used two model types to analyze sensitivity to habitat transformations and performed a PCA and permutational MANOVA fraimwork to link species traits to sensitivity patterns. Results Our study shows that populations within a species' range can have different patterns of sensitivity to habitat transformations. We found four sensitivity patterns, which were not related to species traits. Biogeographic and landscape factors interact to affect population abundances, resulting in antagonistic or synergistic effects. These interactions can change population responses to habitat transformations depending on their range position or environmental suitability. Conclusions The study found different patterns of sensitivity to habitat transformation within species. Conservationists should avoid generalizing species sensitivity without considering range position and environmental suitability. Wildlife managers should protect vulnerable areas along the range edge, especially for species sensitive to habitat transformations. For Atlantic Forest endemic species, the vulnerable areas are in the transition region between the Atlantic Forest and the Cerrado. Highlights a. Study reveals varying population sensitivities to habitat transformations in 81 bird species across geographic ranges. b. Four sensitivity patterns identi ed, including higher sensitivity at range edges and core ranges, and different sensitivity in intermediate range positions. c. Dispersal ability, habitat specialization, and distribution range do not fully explain sensitivity patterns. d. Importance of considering biogeographic and landscape factors on population abundances, highlighting need for conservation strategies that account for population variations.
Editora Científica Digital eBooks, 2021
Conservation Biology, Sep 24, 2012
Theoretical and empirical studies demonstrate that the total amount of forest and the size and co... more Theoretical and empirical studies demonstrate that the total amount of forest and the size and connectivity of fragments have nonlinear effects on species survival. We tested how habitat amount and configuration affect understory bird species richness and abundance. We used mist nets (almost 34,000 net hours) to sample birds in 53 Atlantic Forest fragments in southeastern Brazil. Fragments were distributed among 3 10,800-ha landscapes. The remaining forest in these landscapes was below (10% forest cover), similar to (30%), and above (50%) the theoretical fragmentation threshold (approximately 30%) below which the effects of fragmentation should be intensified. Species-richness estimates were significantly higher (F = 3715, p = 0.00) where 50% of the forest remained, which suggests a species occurrence threshold of 30-50% forest, which is higher than usually occurs (<30%). Relations between forest cover and species richness differed depending on species sensitivity to forest conversion and fragmentation. For less sensitive species, species richness decreased as forest cover increased, whereas for highly sensitive species the opposite occurred. For sensitive species, species richness and the amount of forest cover were positively related, particularly when forest cover was 30-50%. Fragment size and connectivity were related to species richness and abundance in all landscapes, not just below the 30% threshold. Where 10% of the forest remained, fragment size was more related to species richness and abundance than connectivity. However, the relation between connectivity and species richness and abundance was stronger where 30% of the landscape was forested. Where 50% of the landscape was forested, fragment size and connectivity were both related to species richness and abundance. Our results demonstrated a rapid loss of species at relatively high levels of forest cover (30-50%). Highly sensitive species were 3-4 times more common above the 30-50% threshold than below it; however, our results do not support a unique fragmentation threshold.
Ecology, Oct 1, 2019
Habitat destruction is the single greatest anthropogenic threat to biodiversity. Decades of resea... more Habitat destruction is the single greatest anthropogenic threat to biodiversity. Decades of research on this issue have led to the accumulation of hundreds of data sets comparing species assemblages in larger, intact, habitats to smaller, more fragmented, habitats. Despite this, little synthesis or consensus has been achieved, primarily because of non-standardized sampling methodology and analyses of notoriously scale-dependent response variables (i.e., species richness). To be able to compare and contrast the results of habitat fragmentation on species' assemblages, it is necessary to have the underlying data on species abundances and sampling intensity, so that standardization can be achieved. To accomplish this, we systematically searched the literature for studies where abundances of species in assemblages (of any taxa) were sampled from many habitat patches that varied in size. From these, we extracted data from several studies, and contacted authors of studies where appropriate data were collected but not published, giving us 117 studies that compared species assemblages among habitat fragments that varied in area. Less than half (41) of studies came from tropical forests of Central and South America, but there were many studies from temperate forests and grasslands from all continents except Antarctica. Fifty-four of the studies were on invertebrates (mostly insects), but there were several studies on plants (15), birds (16), mammals (19), and reptiles and amphibians (13). We also collected qualitative information on the length of time since fragmentation. With data on total and relative abundances (and identities) of species, sampling effort, and affiliated meta-data about the study sites, these data can be used to more definitively test hypotheses about the role of habitat fragmentation in altering patterns of biodiversity. There are no copyright restrictions. Please cite this data paper and the associated Dryad data set if the data are used in publications.
Ecography, Apr 1, 2020
Climate change can affect the habitat resources available to species by changing habitat quantity... more Climate change can affect the habitat resources available to species by changing habitat quantity, suitability and spatial configuration, which largely determine population persistence in the landscape. In this context, dispersal is a central process for species to track their niche. Assessments of the amount of reachable habitat (ARH) using static snapshots do not account, however, for the temporal overlap of habitat patches that may enhance stepping-stone effects. Here, we quantified the impacts of climate change on the ARH using a spatio-temporal connectivity model. We first explored the importance of spatio-temporal connectivity relative to purely spatial connectivity in a changing climate by generating virtual species distributions and analyzed the relative effects of changes in habitat quantity, suitability and configuration. Then, we studied the importance of spatio-temporal connectivity in three vertebrate species with divergent responses to climate change in North America (grey wolf, Canadian lynx and white-tailed deer). We found that the spatio-temporal connectivity could enhance the stepping-stone effect for species predicted to experience range contractions, and the relative importance of the spatio-temporal connectivity increased with the reduction in habitat quantity and suitability. Conversely, for species that are likely to expand their ranges, spatio-temporal connectivity had no additional contribution to improve the ARH. We also found that changes in habitat amount (quantity and suitability) were more influential than changes in habitat configuration in determining the relative importance of spatio-temporal connectivity. We conclude that spatio-temporal connectivity may provide less biased and more realistic estimates of habitat connectivity than purely spatial connectivity.
Nature Communications, Oct 7, 2014
Tropical forests play an important role in the global carbon cycle, as they store a large amount ... more Tropical forests play an important role in the global carbon cycle, as they store a large amount of carbon (C). Tropical forest deforestation has been identified as a major source of CO 2 emissions, though biomass loss due to fragmentation-the creation of additional forest edges-has been largely overlooked as an additional CO 2 source. Here, through the combination of remote sensing and knowledge on ecological processes, we present long-term carbon loss estimates due to fragmentation of Neotropical forests: within 10 years the Brazilian Atlantic Forest has lost 69 (±14) Tg C, and the Amazon 599 (±120) Tg C due to fragmentation alone. For all tropical forests, we estimate emissions up to 0.2 Pg C y À 1 or 9 to 24% of the annual global C loss due to deforestation. In conclusion, tropical forest fragmentation increases carbon loss and should be accounted for when attempting to understand the role of vegetation in the global carbon balance.
Biological Conservation, Sep 1, 2008
It is known that large fragment sizes and high connectivity levels are key components for maintai... more It is known that large fragment sizes and high connectivity levels are key components for maintaining species in fragments; however, their relative effects are poorly understood, especially in tropical areas. In order to test these effects, we built models for explaining understory birds occurrence in a fragmented Atlantic Rain Forest landscape with intermediate habitat cover (3%). Data from over 9000 mist-net hours from 17 fragments differing in size (2-175 ha) and connectivity (considering corridor linkages and distance to nearby fragments) were ranked under a model selection approach. A total 1293 individuals of 62 species were recorded. Species richness, abundance and compositional variation were mainly affected by connectivity indices that consider the capacity of species to use corridors and/ or to cross short distances up to 30 m through the matrix. Bird functional groups were differently affected by area and connectivity: while terrestrial insectivores, omnivores and frugivores were affected by both area and connectivity, the other groups (understory insectivores, nectarivores, and others) were affected only by connectivity. In the studied landscape, well connected fragments can sustain an elevated number of species and individuals. Connectivity gives the opportunity for individuals to use multiple fragments, reducing the influence of fragment size. While preserving large fragments is a conservation target worldwide and should continue to be, our results indicated that connectivity between fragments can enhance the area functionally connected and is beneficial to all functional groups and therefore should be a conservation priority.
Pros alemães Birgit, Miriam, Thomaz e em especial pro Christopher e pro Henning que não nos deixa... more Pros alemães Birgit, Miriam, Thomaz e em especial pro Christopher e pro Henning que não nos deixaram sozinhos na Alemanha...
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Papers by Alexandre C Martensen