The Relative Importance of Small-Scale and Landscape-Level Heterogeneity in Structuring Small Mammal Distributions

Abstract:Anthropogenic edge effects, whereby disturbance strength increases in proximity to ecotone boundaries, are known to strongly affect individual species but we lack a general understanding of how they vary by species, disturbance type and regional context. We deployed 46 camera-trap stations for a total of 3545 trap-days at two sites in Sulawesi, Indonesia, obtaining 937 detections of five vertebrate species. Anoa (Bubalus spp.) were more abundant near edges, booted macaque (Macaca ochreata) and red jungle fowl (Gallus gallus) were less abundant near edges, and edges did not impact Sulawesi warty pig (Sus celebensis) or Malay civet (Viverra tangalunga). But the relative importance of habitat disturbance from agriculture, roads and villages differed for each species, and edge-induced disturbances varied not only in magnitude but also in direction between the study areas. In the strongest instance, macaque local abundance was 3.5 times higher near villages than it was 3 km into the forest in one reserve, but 2.8 times higher 3 km into the forest than near villages in the other reserve. Our results suggest that responses to habitat edges among species and edge types are idiosyncratic, and that landscape-level context can strongly alter the influence of local disturbance on biodiversity.

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Resilience of Zostera muelleri seagrass to small‐scale disturbances: the relative importance of asexual versus sexual recovery

Ecology and Evolution ◽

10.1002/ece3.933 ◽

2014 ◽

Vol 4 (4) ◽

pp. 450-461 ◽

Cited By ~ 42

Author(s):

Peter I. Macreadie ◽

Paul H. York ◽

Craig D.H. Sherman

Keyword(s):

Small Scale ◽

Relative Importance

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The Use of Large Scale Parameters in Small Scale Diffusion Studies

Bulletin of the American Meteorological Society ◽

10.1175/1520-0477-38.1.1.6 ◽

1957 ◽

Vol 38 (1.1) ◽

pp. 6-12 ◽

Cited By ~ 1

Author(s):

William G. Tank

Keyword(s):

Large Scale ◽

Meteorological Parameters ◽

Surface Wind ◽

Small Scale ◽

Relative Importance ◽

Wind Vector ◽

Scale Parameters ◽

Diffusion Studies ◽

The Mean ◽

Low Levels

A method is set forth whereby gaseous diffusion in the low levels of the atmosphere can be calculated by Roberts' diffusion equation (modified to consider instantaneous volume sources) using only large scale synoptic parameters that are readily obtainable from the surface analysis and pibal reports. The three pertinent meteorological parameters utilized are: (1) the mean surface wind, (2) the angle between the surface wind vector and the surface isobars, and (3) the height of the gradient level. Theoretical and observed dosage values are compared by means of dosage isopleth diagrams. Results show that the method yields quite satisfactory results, with regard to both dosage magnitude and distribution. The assumptions necessary for the application of the method and its limitations are mentioned and their relative importance discussed.

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Recovery of small rodent populations after population collapse

Wildlife Research ◽

10.1071/wr14165 ◽

2015 ◽

Vol 42 (2) ◽

pp. 108 ◽

Cited By ~ 9

Author(s):

S. Hein ◽

J. Jacob

Keyword(s):

Population Size ◽

Pest Control ◽

Small Mammal ◽

Recovery Time ◽

Small Scale ◽

Small Rodent ◽

Population Recovery ◽

Population Collapse ◽

Small Mammal Population ◽

Recovery Mechanisms

In this review we summarise published knowledge regarding small mammal population recovery following sudden population collapse, regardless as to whether the collapse is caused by natural or man-made events. We determine recovery mechanisms, recovery time and recovery rate, and suggest how to adapt and optimise current methods to regulate small mammal population size, for pest management and/or conservation. It is vital that the principles underlying the recovery mechanisms are known for both pest control and conservation to align management methods to either maintain animal numbers at a permanent minimum level or increase population size. Collapses can be caused naturally, as in the declining phase of multi-annual fluctuations and after natural disasters, or by man-made events, such as pesticide application. In general, there are three ways population recovery can occur: (1) in situ survival and multiplication of a small remaining fraction of the population; (2) immigration; or (3) a combination of the two. The recovery mechanism strongly depends on life history strategy, social behaviour and density-dependent processes in population dynamics of the species in question. In addition, the kind of disturbance, its intensity and spatial scale, as well as environmental circumstances (e.g. the presence and distance of refuge areas) have to be taken into account. Recovery time can vary from a couple of days to several years depending on the reproductive potential of the species and the type of disturbances, regardless of whether the collapse is man made or natural. Ultimately, most populations rebound to levels equal to numbers before the collapse. Based on current knowledge, case-by-case decisions seem appropriate for small-scale conservation. For pest control, a large-scale approach seems necessary. Further investigations are required to make sound, species-specific recommendations.

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Promoting Landscape-Level Forest Management in Fire-Prone Areas: Delegate Management to a Multi-Owner Collaborative, Rent the Land, or Just Sell It?

Forests ◽

10.3390/f13010022 ◽

2021 ◽

Vol 13 (1) ◽

pp. 22

Author(s):

Ana Martins ◽

Ana Novais ◽

José Lima Santos ◽

Maria João Canadas

Keyword(s):

Forest Management ◽

A Priori ◽

Policy Option ◽

Small Scale ◽

Forest Owner ◽

Target Area ◽

Management Options ◽

Forest Ownership ◽

Landscape Level Management ◽

Landscape Level

Forest management at the landscape level is a requirement for reducing wildfire hazard. In contexts where non-industrial private forest ownership prevails, the collaboration among multiple owners has been proposed as the way forward to reach consistent fuel management at that level. The current literature has been focused on identifying the factors that lead to collaboration among owners. In this study we explored other ways to reach landscape-level management in addition to the collaborative way, such as those that may be promoted through land renting or selling. Different contexts and owner types may require different solutions. Thus, we explicitly asked which alternative would be chosen by a given forest owner, from the following set: keeping individual management, entering a multi-owner collaborative arrangement where they delegate management, renting to a pulp company; or selling the land. In a context of small-scale ownership and high recurrence of wildfires in Portugal, a face-to-face survey was carried out to a sample of landowners. Our results suggest that there is not an a priori generalized unwillingness of owners to delegate management, rent or sell the land and thus they seem prone to align themselves with policy strategies to promote management at the landscape level. Multinomial logit regression modelling allowed us to explain and predict owners’ choices among the aforementioned set of alternative management options. We found that choosing multi-ownership collaboration, as opposed to keeping current individual management, is associated with passive management under harsher conditions, by non-residents without bonding capital. The identified factors of owners’ choices show the limited scope of tenancy and land-market mechanisms to promote landscape-level management. The best policy option was found to depend on the owner profiles prevailing in the target area. This suggests that studying the existing context and owner types is required to design effective policies.

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Small mammals and habitat structure in lowland rain forest of Peninsular Malaysia

Journal of Tropical Ecology ◽

10.1017/s0266467400000043 ◽

1985 ◽

Vol 1 (1) ◽

pp. 5-22 ◽

Cited By ~ 20

Author(s):

Catherine Kemper ◽

David T. Bell

Keyword(s):

Small Mammal ◽

Rain Forest ◽

Habitat Structure ◽

Primary Forest ◽

Small Scale ◽

Simple Method ◽

Habitat Differences ◽

Faunal Distribution ◽

Habitat Variables ◽

Trapping Sites

ABSTRACTA method of assessing rain forest structure by ranking relative abundance of 41 habitat variables was used to describe habitat differences among six trapping sites (324 subsites). Variables included aspects of all vegetation layers but concentrated on those considered to be important to small mammal distribution. Ordination and classification methods resulted in similar analyses of the data. Differences in habitat structure were primarily related to the moisture conditions of the trapping sites and secondarily to their successional age (regenerating versus primary forest). The most important habitat variables for differentiating between sites were LITTER, CLEARING, SOILS, PIG DAMAGE, FLOODING, FAN PALM, EMERGENTS, CANOPY SURFACE and SEEDLINGS. Habitat structure also varied within sites with some suggestion of small-scale patterning.Small mammal captures were more likely in drier sites and subsites, but there was no difference in trap success between regenerating sites and primary forest sites. Greater numbers of species were captured in sites containing a variety of habitats, a discrete layering of vegetation and an extensive understorey. Small mammal captures were positively associated with five habitat variables (EMERGENTS, LITTER, ROTTING LOGS, SEEDLINGS, ROUGH BARK) and negatively associated with five others (LAYERS, BERTAM, SEDGES, PIG DAMAGE, FLOODING). The destruction caused by pigs is thought to be a major factor since it reduces litter and food availability over wide areas. Leopoldamys sabanus was the most abundant small mammal captured (40/68 individuals) and trap success differences among sites (0.4–1.9%) reflect its preference for higher, well-drained habitats.The study demonstrates the usefulness of a simple method of ranking habitat features according to importance/abundance thus eliminating the all but impossible task of direct measurements in this complex system. This simple method of habitat description provides a basis for studying variables influencing faunal distribution patterns.

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Measuring the filamentary structure of interstellar clouds through wavelets

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731596 ◽

2018 ◽

Vol 621 ◽

pp. A5 ◽

Cited By ~ 6

Author(s):

V. Ossenkopf-Okada ◽

R. Stepanov

Keyword(s):

Wavelet Analysis ◽

Column Density ◽

Small Scale ◽

Global Alignment ◽

Relative Importance ◽

Data Set ◽

Filamentary Structure ◽

Density Maps ◽

Anisotropic Structures ◽

Cylindrical Collapse

Context. The ubiquitous presence of filamentary structures in the interstellar medium asks for an unbiased characterization of their properties including a stability analysis. Aims. We propose a novel technique to measure the spectrum of filaments in any two-dimensional data set. By comparing the power in isotropic and anisotropic structures we can measure the relative importance of spherical and cylindrical collapse modes. Methods. Using anisotropic wavelets we can quantify and distinguish local and global anisotropies and measure the size distribution of filaments. The wavelet analysis does not require any assumptions on the alignment or shape of filaments in the maps, but directly measures their typical spatial dimensions. In a rigorous test program, we calibrate the scale dependence of the method and test the angular and spatial sensitivity. We apply the method to molecular line maps from magneto-hydrodynamic (MHD) simulations and observed column-density maps from Herschel observations. Results. When applying the anisotropic wavelet analysis to the MHD data, we find that the observed filament sizes depend on the combination of magnetic-field-dominated density–velocity correlations and radiative transfer effects. This can be exploited by observing tracers with different optical depth to measure the transition from a globally ordered large-scale structure to small-scale filaments with entangled field lines. The unbiased view to Herschel column-density maps does not confirm a universal characteristic filament width. The map of the Polaris Flare shows an almost scale-free filamentary spectrum up to the size of the dominating filament of about 0.4 pc. For the Aquila molecular cloud the range of filament widths is limited to 0.05–0.2 pc. The filaments in Polaris show no preferential direction in contrast to the global alignment that we trace in Aquila. Conclusions. By comparing the power in isotropic and anisotropic structures we can measure the relative importance of spherical and cylindrical collapse modes and their spatial distribution.

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