Winners and Losers: How Woody Encroachment Is Changing the Small Mammal Community Structure in a Neotropical Savanna

Years of fire suppression, decreases in herbivores, and global climate change have led to shifts in savannas worldwide. Natural open vegetation such as grasslands and shrublands is increasing in wood density, but the effects for small mammals are not well understood. While most of the mammal studies from the Brazilian Cerrado are concentrated in the core area of this large Neotropical savanna, its southern portions are suffering from biome shifting through woody encroachment. Herein, we surveyed a small mammal community from the southeastern boundary of Cerrado (Santa Bárbara Ecological Station) and evaluated the micro and macro environmental variables shaping community structure in order to investigate how the woody encroachment in the last 15 years may have influenced this assemblage. We recorded 17 species of marsupials and rodents along five distinct habitats in a gradient from grasslands to woodlands. Although richness was not affected by microhabitat variables, total and relative abundance varied according to habitat type and in relation to herbaceous, shrub, and tree density. Rodents such as Calomys tener and Clyomys laticeps were positively affected by increasing herb cover, Cerradomys scotti and Oligoryzomys nigripes by shrub cover, while the marsupial Didelphis albiventris had higher association with increasing tree cover. We detected an increase of 27.4% in vegetation density (EVI) between 2003 and 2018 in our study site, and this woody encroachment negatively affected the abundance of some small mammals. The open-area specialists Cryptonanus chacoensis and C. scotti had a decrease in abundance, while D. albiventris and O. nigripes were favored by woody encroachment. Our data suggest that woody encroachment is shifting community composition: small mammals often associated with grasslands and open savannas are likely to be negatively affected by woody encroachment; while species that rely on tree-covered habitats are likely to benefit from an increasing woody landscape. Therefore, forest-dwellers are gradually replacing open-vegetation inhabitants. Active management of open formations (e.g., with prescribed burning) may be needed to maintain Cerrado biodiversity, especially considering the open-area endemics.

Download Full-text

Small mammals in a semi-arid community, with particular reference to Ningaui yvonneae

Australian Mammalogy ◽

10.1071/am00103 ◽

2000 ◽

Vol 22 (2) ◽

pp. 103 ◽

Cited By ~ 6

Author(s):

SM Carthew ◽

T Keynes

Keyword(s):

Community Structure ◽

Small Mammals ◽

Small Mammal ◽

South Australia ◽

Sampling Period ◽

Field Trips ◽

Mus Domesticus ◽

Small Mammal Community ◽

Mammal Community ◽

Semi Arid

Small mammal community structure was investigated at a semi-arid mallee site in the Middleback Ranges of South Australia during 14 field trips conducted over four years. During this time, 291 small mammals were caught from 6579 trap nights (trap success 4.4%). Ningaui yvonneae was the most abundant and frequently recorded species (199 captures), followed by Cercartetus concinnus (75 captures). Other species caught infrequently were Sminthopsis dolichura (2 captures), Notomys mitchellii (3 captures), Pseudomys bolami (2 captures) and Mus domesticus (10 captures). Ningaui yvonneae was the only species caught during all sampling periods. Males were trapped more frequently than females (117 : 43). Recapture rates were low, with only eight of 160 individuals caught during more than one sampling period. This may reflect the mobility of the species. Distances moved between successive recaptures within a sampling period averaged less than 100 m, while between sampling periods distances averaged more than 450 m. This is the first published study to capture N. yvonneae regularly and in reasonable numbers.

Download Full-text

Effect of fragmentation of kerangas forest on small mammal community structure in Brunei Darussalam

Scientia Bruneiana ◽

10.46537/scibru.v16i2.62 ◽

2018 ◽

Vol 16 (2) ◽

Author(s):

Siti Salwa Abd Khalid ◽

Ulmar Grafe

Keyword(s):

Species Richness ◽

Community Structure ◽

Small Mammals ◽

Small Mammal ◽

Forest Types ◽

Brunei Darussalam ◽

Small Mammal Community ◽

Mammal Community ◽

Forest Size ◽

Fragmented Forests

Widespread and rapid forest loss and disturbance have resulted in increased fragmentation of tropical forests. The impacts of forest disturbance and fragmentation on small mammals have been widely studied across the tropics and these studies have highlighted the detrimental effects. However, there is limited understanding on the impacts on small mammals in Borneo. This study investigated the impacts of fragmentation on small mammal community structure in lowland coastal heath forests known as kerangas forests, in Brunei Darussalam. Twelve study sites were compared in three forest types: fragmented (2.07-17.6 ha), disturbed (443.55-483.79 ha) and undisturbed (>500 ha) forests. In addition, the correlations between species richness, abundance and biomass of small mammals, and forest size were investigated. There was a clear change in species composition in the different forest types. Fragmented forests had the lowest species richness but the highest pooled abundance and biomass compared with disturbed and undisturbed forests. Species richness increased with forest size as predicted by the theory of island biogeography. In contrast, abundance and biomass was negatively correlated to forest size. Factors that contribute to the pronounced decline in species richness in fragmented forests include loss of rare and native forest species, reduced forest size in fragmented forests and distance effect. We suggest that a release from top-down control by predators and favourable conditions as a result from forest fragmentation are responsible for higher abundance and biomass of small mammals in fragmented forests.

Download Full-text

Community structure and population dynamics of small mammals in an urban-sylvatic interface area in Rio de Janeiro, Brazil

Zoologia (Curitiba) ◽

10.3897/zoologia.35.e13465 ◽

2018 ◽

Vol 35 ◽

pp. 1-12

Author(s):

Rosana Gentile ◽

Thiago S. Cardoso ◽

Sócrates F. Costa-Neto ◽

Bernardo R. Teixeira ◽

Paulo S. D'Andrea

Keyword(s):

Population Dynamics ◽

Species Richness ◽

Community Structure ◽

Atlantic Forest ◽

Small Mammals ◽

Small Mammal ◽

Rio De Janeiro ◽

Interface Area ◽

Small Mammal Community ◽

Mammal Community

The Atlantic Forest is one of the most disturbed Brazilian biomes, with 183 out of 298 species of mammals occurring in the state of Rio de Janeiro. In this study, we aimed to characterize the diversity, community structure, and habitat use of small mammals in the FIOCRUZ Atlantic Forest Campus (CFMA), including areas of Pedra Branca State Park (PBSP, subunit Pau da Fome), state of Rio de Janeiro. We also compared species diversity and composition between two moments 15 years apart (2001 and 2012–2015) and analyzed the population dynamics of the marsupial Didelphisaurita (Wied-Neuwied, 1826). Small mammal captures were made in different habitats: sylvatic-urban interface areas near human dwellings, disturbed forest, and preserved forest areas. Five marsupial species and four rodent species were captured in both periods. There was a reduction in species richness and β diversity between the two periods, indicating that disturbances in the environment over the years may have affected the small mammal community structure. The most altered environment showed the greatest species richness and abundance, while the forest areas showed the smallest values, which may be explained by the loss of mammal species, mainly specialist species in forested areas. We identified three groups of species according to habitat preferences: one related to environments with a higher density of vegetation in upper strata – Marmosaparaguayana (Tate, 1931) and Monodelphisamericana (Müller, 1776), another related to a higher density in lower forest strata – Akodoncursor (Winge, 1887), and another with no association with the investigated habitat variables – D.aurita and Oligoryzomysnigripes (Olfers, 1818). The small mammal community structure showed a low level of nestedness in both sampling periods. This study is the first report to evaluate the community structure of small mammals in the sylvatic-urban interface area of Pedra Branca State Park, the largest forest reserve within an urban area in Brazil. The surveys indicate that the small mammal diversity was low in both sampling periods and in both areas, and a species loss in the Pau da Fome locality was observed, despite it is a conservation unit. The greater species abundance and richness in the most disturbed areas suggest an increase of factors favoring the occurrence of synanthropic and opportunistic species.

Download Full-text

Grass height is the determinant of sheep grazing effects on small mammals in a savanna ecosystem

The Rangeland Journal ◽

10.1071/rj13063 ◽

2013 ◽

Vol 35 (4) ◽

pp. 403 ◽

Cited By ~ 5

Author(s):

T. R. Kuiper ◽

D. M. Parker

Keyword(s):

Community Structure ◽

Small Mammals ◽

Small Mammal ◽

Biodiversity Loss ◽

Food Competition ◽

Ovis Aries ◽

Suitable Habitat ◽

Dynamic Interactions ◽

Small Mammal Community ◽

Mammal Community

Small mammals play an important role in many ecosystems; hence, the factors that influence their community structure are of interest. Ungulate grazing is one such factor, and this study focussed on the effect of sheep (Ovis aries) grazing in a savanna ecosystem on small-mammal community structure. In a landscape-scale assessment, small-mammal community structure was compared at three different levels of grazing on a sheep farm in the Sub-Escarpment Savanna of the Eastern Cape, South Africa. In total, 97 small-mammal individuals across seven species were trapped. Of these individuals, 81.4% were trapped on the no-grazing control, whereas 15.5% and 3.1% were trapped on the medium- and high-grazing treatments, respectively. The results showed that the only significant differences in abundance, diversity, evenness, and richness of small mammals among grazing treatments were those mediated by the effect of grazing on grass height. It is proposed that the reduction in grass height associated with grazing is the primary mechanism by which sheep adversely affect small mammals in this ecosystem. This could be explained by the increased exposure of small mammals to predators after grazing of grass by sheep, and food competition between sheep and small mammals. The data also suggest that small mammals may persist in small and isolated patches of suitable habitat (long grass) within heavily grazed pastures subjected to rotational grazing. In the broader context of community ecology, this study sheds light on cryptic and dynamic interactions between two quite different grazing guilds. Experimental work of this kind may help to determine the role of introduced sheep in biodiversity loss of small mammals across the globe.

Download Full-text

Changes in small mammal communities after logging in north-central Ontario

Canadian Journal of Zoology ◽

10.1139/z83-130 ◽

1983 ◽

Vol 61 (5) ◽

pp. 970-980 ◽

Cited By ~ 40

Author(s):

Arthur M. Martell

Keyword(s):

Small Mammals ◽

Small Mammal ◽

Vegetative Cover ◽

North Central ◽

Clear Cut ◽

Clear Cutting ◽

Small Mammal Community ◽

Small Mammal Communities ◽

Mammal Community ◽

Mammal Communities

Changes in small mammal communities following logging were monitored in clear-cut and strip-cut upland black spruce (Picea mariana) stands and in selectively cut mixed wood stands in north-central Ontario. Clear-cutting and subsequent scarification essentially eliminated the vegetative cover. Much of the ground cover recovered within 5 years and shrubs within 12 years, but mosses and lichens took much longer. The small mammal community in both clear-cut and strip-cut stands changed over the first three years after logging from one dominated by southern red-backed voles (Clethrionomys gapperi) to one dominated by deer mice (Peromyscus maniculatus) and then remained relatively stable for up to 13 years after harvest. That shift was not apparent in selectively cut mixed wood stands where the composition of the small mammal community was similar between uncut stands and stands 4–23 years after harvest. There was relatively little change in total numbers of small mammals after logging. In general, the diversity and evenness of small mammals increased or remained stable in the first 1–3 years following harvest, decreased on older (3–16 years) cuts, and then increased to values similar to those in uncut stands on the oldest (19–23 years) cuts.

Download Full-text

Influence of off-road vehicle trails on small mammal community structure in western Maryland

Journal of the Pennsylvania Academy of Science ◽

10.5325/jpennacadscie.94.1-2.0039 ◽

2021 ◽

Vol 94 (1-2) ◽

pp. 39

Author(s):

Thady ◽

Harlon ◽

Edwards ◽

Lambert

Keyword(s):

Community Structure ◽

Small Mammal ◽

Road Vehicle ◽

Small Mammal Community ◽

Mammal Community

Download Full-text

Use by small mammals of a chronosequence of tropical rainforest revegetation

Wildlife Research ◽

10.1071/wr14082 ◽

2014 ◽

Vol 41 (3) ◽

pp. 233 ◽

Cited By ~ 5

Author(s):

Tegan Whitehead ◽

Miriam Goosem ◽

Noel D. Preece

Keyword(s):

Community Composition ◽

Small Mammals ◽

Small Mammal ◽

Tropical Rainforest ◽

Management Technique ◽

Population Declines ◽

North Eastern ◽

Small Mammal Community ◽

Mammal Community ◽

Abundance And Diversity

Context The conversion of tropical rainforest to grazing pasture results in a drastic change in small-mammal community composition. Restoring the landscape through ecological revegetation is thus an increasingly important management technique to conserve rainforest mammals. Aims This study aimed to determine the habitat ages at which species of small mammals recolonised revegetated habitats on the southern Atherton Tablelands, north-eastern Queensland, Australia. We focussed on changes in rainforest mammal abundance and diversity with increasing habitat age. Methods Small-mammal trapping and mark–recapture techniques investigated mammal diversity, abundance and community composition within remnant rainforest, three age classes of ecological revegetation and abandoned grazing pasture. Key results Small-mammal community composition differed between remnant rainforest and abandoned grazing pasture. The pasture and 3-year old revegetated sites were similar in composition, both lacking rainforest small mammals. Six- and 7-year old revegetation plantings provided suboptimal habitat for both rainforest and grassland mammals, whereas 16- and 22-year old revegetated habitats were dominated by rainforest species, with some individuals being frequently recaptured. Conclusions As revegetated habitats aged, the small-mammal community composition transitioned from a grassland-like composition to a community dominated by rainforest species. Implications Although rainforest small mammals were very occasionally captured within the 6- and 7-year old habitats, revegetated plantings were not dominated by rainforest species until the habitat was 16 years old. This highlights the importance of commencing revegetation as early as possible to minimise future population declines and maximise the conservation of rainforest mammals.

Download Full-text