scholarly journals Effects of habitat fragmentation on the persistence of medium and large mammal species in the Brazilian Savanna of Goiás State

2018 ◽  
Vol 18 (3) ◽  
Author(s):  
Ednaldo Cândido Rocha ◽  
Daniel Brito ◽  
Paulo Machado e Silva ◽  
Jhefferson Silva ◽  
Paulo Vitor dos Santos Bernardo ◽  
...  
Keyword(s):  
Species Richness ◽  
Habitat Loss ◽  
Time Lag ◽  
Important Variable ◽  
Mammal Species ◽  
Habitat Amount ◽  
Large Mammal ◽  
Local Extinctions ◽  
Short Time ◽  
Current Species

Abstract: Habitat loss and fragmentation are the main threats to the conservation of Cerrado biodiversity. The objective of this study was to evaluate the implications of habitat loss on the persistence of medium and large mammal species, considering the spatial and temporal changes (years 1985, 2000 and 2014) to the evaluated fragments. The study was carried out in 14 fragments (10.5 - 618 ha), located in Southeastern Goiás, Brazil. Records for 24 mammal species were obtained and revealed the two sites with the largest habitat amount in the landscape contained higher species richness than the remaining sites. The three mammal groups based on body mass (weight < 5 kg; weight between 5 and 20 kg; and weight > 20 kg) analyzed in this study showed different responses regarding landscape changes. For larger mammals (between 5 - 20 kg and > 20 kg), there was significant association between current species richness and the amount of habitat in 2014, while the species richness of smaller mammals did not significantly correlate with any of the variables assessed for any of the years. Therefore, the amount of habitat present within the current landscape was the most important variable regarding mammal species richness, especially for the larger species. The time lag was not evident at the time scale evaluated, and this delay in response may have occurred in a relatively short time (< 15 years). For the remaining fragments in the studied landscapes, most are too small to support populations of some larger mammal species and may also leave individuals more vulnerable to anthropogenic actions (e.g. hunting), whose effects may accelerate local extinctions.

scholarly journals Medium and large mammals in a Cerrado fragment in Southeast Goiás, Brazil: inventory and immediate effects of habitat reduction on species richness and composition

2019 ◽  
Vol 19 (3) ◽  
Author(s):  
Ednaldo Cândido Rocha ◽  
Jhefferson Silva ◽  
Pablo Timóteo da Silva ◽  
Márcio da Silva Araújo ◽  
André Luis da Silva Castro
Keyword(s):  
Species Richness ◽  
Time Lag ◽  
Long Term Effects ◽  
Mammal Species ◽  
Complete Collection ◽  
Large Mammal ◽  
Remnant Vegetation ◽  
Animal Burrows ◽  
Period 2 ◽  
Species Similarity

Abstract: The reduction and fragmentation of remnant vegetation habitats has been one of the main threats to Cerrado biodiversity. The aim of the present study is to make an inventory of medium and large mammal species in a Cerrado remnant and to assess deforestation influence on part of this fragment on the richness and composition of mammal species. The study was conducted in a Cerrado fragment in southeast Goias State, Ipameri County. Data were collected during three different periods (P1, January-June, 2014; P2, December, 2016 - June, 2017; P3, July-December, 2017) through direct (visual, vocal and camera-trap records) and indirect methods (foot prints, animal burrows and other traces) in order to register the mammal species. Jackknife 1 estimator was used to estimate species richness during each of the three sampled periods and for the complete collection period; species similarity between periods was assessed through the Jaccard's Index of Similarity (Cj). Species richness between periods was performed through inference by overlapping confidence intervals (CI). Twenty-nine species were recorded during the assessed period, five of them were listed as endangered in Brazil. There was no significant change in species richness between the assessed periods: species richness of 25 species was observed in Period 1 (P1), the richness of 32 species was estimated (CI = 4.58); 23 species were recorded in Period 2 (P2), and the richness of 30 species was estimated (CI = 4.39), the richness of 23 species was observed in Period 3 (P3) and the richness of 28 species was estimated (CI = 4.70). Similarity in species composition between the assessed periods recorded Cj = 0.71 (71%) between P1 and P2, Cj = 0.66 (66%) between P1 and P3, and Cj = 0.77 between P2 and P3. Fragment deforestation did not influence the richness and composition of medium and large mammal species (within a period of 2~3 years) when the three periods were compared; however, the absence of changes in the community can be the result of time-lag, therefore, we cannot put aside the likelihood of mid and long-term effects.

scholarly journals Large mammal species richness and late Quaternary precipitation change in south-western Australia

2016 ◽  
Vol 32 (6) ◽  
pp. 760-769 ◽  
Author(s):  
J. Tyler Faith ◽  
Joe Dortch ◽  
Chelsea Jones ◽  
James Shulmeister ◽  
Kenny J. Travouillon
Keyword(s):  
Species Richness ◽  
Western Australia ◽  
Late Quaternary ◽  
Precipitation Change ◽  
Mammal Species ◽  
Large Mammal

Performance of individual species as indicators for large mammal species richness in Northern Tanzania

2015 ◽  
Vol 53 ◽  
pp. 70-77 ◽  
Author(s):  
Christian Kiffner ◽  
Michael Albertini ◽  
Alena Ede ◽  
Brenna Donnellan ◽  
Nathan Hahn ◽  
...  
Keyword(s):  
Species Richness ◽  
Individual Species ◽  
Mammal Species ◽  
Large Mammal ◽  
Northern Tanzania

scholarly journals Biogeography of Mammals in Rocky Mountain National Parks

1991 ◽  
Vol 15 ◽  
pp. 25-28
Author(s):  
Susan Glenn ◽  
Brian Chapman ◽  
Rebecca Rudman ◽  
Ian Butler
Keyword(s):  
Species Richness ◽  
National Parks ◽  
Rocky Mountain ◽  
Effective Area ◽  
Habitat Diversity ◽  
Initial Population ◽  
Mammal Species ◽  
Number Of Species ◽  
Local Extinctions ◽  
Equilibrium Number

The equilibrium theory of island biogeography proposes that on an island of a given area, there exists an equilibrium number of species when the rates of immigration and local extinction of species are equal (MacArthur and Wilson 1967). This theory has been applied to park systems because parks may act as functional islands when surrounding unprotected land is cleared of natural vegetation. Alteration of these surrounding habitats isolates these parks and reduces the effective area, causing a decrease in the equilibrium number of species. In animal communities, this process is called faunal collapse (Soule et al. 1979).The effects of park isolation and faunal collapse have been studied for mammals in Rocky Mountain parks (Picton 1979, Newmark 1986, Glenn and Nudds 1989). In western U.S. parks, extinctions were more numerous in smaller or older parks (Newmark 1987). Area, topographic diversity, and habitat diversity have been correlated with mammal species richness in western North American parks (Picton 1979, Newmark 1986). Initial population size was also related to the extinction probability of a species (Newmark 1986). It has been proposed that all parks in a region are subject to similar factors influencing local extinctions, and therefore a similar suite of species should become locally extinct in all parks (Patterson and Atmar 1986, Patterson 1987). This means that a nested subset pattern is produced, where parks with low species richness contain mainly species already present in parks with high species richness. This pattern was not found for Canadian parks, where even small parks contained different species assemblages (Glenn 1990). The objectives of this three-year study are to: (i) identify mammal species that have become locally extinct in each of the Rocky Mountain National Parks; (ii) distinguish between hypotheses regarding the causes of these local extinctions in National Parks; (iii) determine if the same species become locally extinct in all parks; and (iv) identify potential sites for future protection of species prone to extinction.

scholarly journals Large mammal species richness and habitat use in an upper Amazonian forest used for ecotourism

2011 ◽  
Vol 76 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Salvador Salvador ◽  
Miguel Clavero ◽  
Renata Leite Pitman
Keyword(s):  
Species Richness ◽  
Habitat Use ◽  
Mammal Species ◽  
Large Mammal ◽  
Amazonian Forest

scholarly journals Habitat fragmentation and species diversity in competitive species communities

2018 ◽  
Author(s):  
Joel Rybicki ◽  
Nerea Abrego ◽  
Otso Ovaskainen
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Habitat Loss ◽  
Empirical Studies ◽  
Negative Effects ◽  
Habitat Amount ◽  
Linear Effect ◽  
Heterogeneous Habitats ◽  
Competitive Species ◽  
Per Se

Abstract.Habitat loss is one of the key drivers of the ongoing decline of biodiversity. However, ecologists still argue about how fragmentation of habitat (independent of habitat loss) affects species richness. The recently proposed habitat amount hypothesis posits that species richness only depends on the total amount of habitat in a local landscape. On the other hand, different empirical studies report contrasting patterns: some find positive and others negative effects of fragmentation per se on species richness.To explain this apparent disparity, we devise a stochastic, spatially-explicit model of competitive species communities in heterogeneous habitats. The model shows that habitat loss and fragmentation have a non-monotone and non-linear effect on the species diversity in competitive communities. When the total amount of habitat is large, fragmentation per se tends to increase species diversity, but if the total amount of habitat is small, the situation is reversed: fragmentation per se decreases species diversity.

scholarly journals Overfishing and habitat loss drive range contraction of iconic marine fishes to near extinction

2021 ◽  
Vol 7 (7) ◽  
pp. eabb6026
Author(s):  
Helen F. Yan ◽  
Peter M. Kyne ◽  
Rima W. Jabado ◽  
Ruth H. Leeney ◽  
Lindsay N.K. Davidson ◽  
...  
Keyword(s):  
Habitat Loss ◽  
Coastal Waters ◽  
Marine Fishes ◽  
Similar Species ◽  
Range Contraction ◽  
Historical Distribution ◽  
Local Extinctions ◽  
Near Extinction ◽  
Over Time

Extinctions on land are often inferred from sparse sightings over time, but this technique is ill-suited for wide-ranging species. We develop a space-for-time approach to track the spatial contraction and drivers of decline of sawfishes. These iconic and endangered shark-like rays were once found in warm, coastal waters of 90 nations and are now presumed extinct in more than half (n = 46). Using dynamic geography theory, we predict that sawfishes are gone from at least nine additional nations. Overfishing and habitat loss have reduced spatial occupancy, leading to local extinctions in 55 of the 90 nations, which equates to 58.7% of their historical distribution. Retention bans and habitat protections are urgently necessary to secure a future for sawfishes and similar species.

scholarly journals Reconciling Lagrangian Diffusivity and Effective Diffusivity in Contour-Based Coordinates

2019 ◽  
Vol 49 (6) ◽  
pp. 1521-1539
Author(s):  
Yu-Kun Qian ◽  
Shiqiu Peng ◽  
Chang-Xia Liang
Keyword(s):  
Time Lag ◽  
Effective Diffusivity ◽  
Delta Function ◽  
Spreading Rate ◽  
Particle Dispersion ◽  
Small Scale ◽  
Time Lags ◽  
Conservative Tracer ◽  
Stirring Effect ◽  
Short Time

AbstractThe present study reconciles theoretical differences between the Lagrangian diffusivity and effective diffusivity in a transformed spatial coordinate based on the contours of a quasi-conservative tracer. In the transformed coordinate, any adiabatic stirring effect, such as shear-induced dispersion, is naturally isolated from diabatic cross-contour motions. Therefore, Lagrangian particle motions in the transformed coordinate obey a transformed zeroth-order stochastic (i.e., random walk) model with the diffusivity replaced by the effective diffusivity. Such a stochastic model becomes the theoretical foundation on which both diffusivities are exactly unified. In the absence of small-scale diffusion, particles do not disperse at all in the transformed contour coordinate. Besides, the corresponding Lagrangian autocorrelation becomes a delta function and is thus free from pronounced overshoot and negative lobe at short time lags that may be induced by either Rossby waves or mesoscale eddies; that is, particles decorrelate immediately and Lagrangian diffusivity is already asymptotic no matter how small the time lag is. The resulting instantaneous Lagrangian spreading rate is thus conceptually identical to the effective diffusivity that only measures the instantaneous irreversible mixing. In these regards, the present study provides a new look at particle dispersion in contour-based coordinates.

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