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961.
Stephanie Kramer-Schadt Tobias S. Kaiser Karin Frank Thorsten Wiegand 《Landscape Ecology》2011,26(4):501-513
With habitat loss and fragmentation having become two of the major threats to the viability of species, the question of how
to manage landscapes for species conservation has attracted much attention. In this context, the planning of stepping stones
has been proposed to increase connectivity in fragmented landscapes. We present a simulation study with a neutral landscape
approach to assess the effects of stepping stones on colonization success. To that end, we used a spatially explicit, calibrated
population model of the European lynx (Lynx lynx) coupled with structured landscapes, in which we could control the landscape parameters of dispersal habitat coverage and
contagion, as well as the number and size of stepping stones available for breeding. In general, we found that colonization
success increased with increasing habitat coverage but decreased with increasing habitat contagion, while the introduction
of stepping stones had significant effects in critical situations. Especially at low to medium dispersal habitat coverage
and high disperser mortality, stepping stones had a positive effect on colonization success when they were large enough to
produce new dispersers, but negative effects when they were small and located in a way that dispersers would be distracted
from more suitable breeding habitat patches. The latter clearly constituted a shading effect and argues for a thorough consideration
of the trade-offs related to stepping stone size and location when implementing stepping stones as a conservation measure,
especially when the number of individuals of conservation concern is low. 相似文献
962.
Protection of biodiversity and ecosystem functions requires a better understanding of spatial diversity. Here we studied diversity
patterns of true bugs and saproxylic beetles, sampled in 28 forest stands of southern Germany, using a hierarchical nested
design of five increasingly broader spatial levels: trap location, stratum, forest stand, forest site, and ecoregion. We predicted
that: (1) for large body-sized species (as a surrogate for highly mobile species) and host generalist species (low host specificity),
the proportion of β-diversity decreases from small to large spatial scales; and (2) the differences between trait-based functional
guilds in the proportion of β-diversity increase with increasing weighting of more-abundant species. Our results indicated
that the ecoregion level is the most important diversity scale for both taxa and among functional guilds sampled, followed
by the forest stand level. Specialized species were more strongly affected on the ecoregion level than generalist species.
Differences in the proportion of β-diversity between functional guilds increased with increasing weighting of abundant species.
The β-diversity patterns based on body size and host specificity were similar for true bugs, but partly contrasting for saproxylic
beetles. Our results suggest that (1) future conservation schemes should focus on establishing new conservation sites in new
ecoregions, rather than on enlarging existing protected areas; (2) host specificity might be a more meaningful trait than
body size to be considered in biodiversity studies; and (3) common conservation approaches restricted to only large, conspicuous,
but rare species might result in a mismatch of important biodiversity scales. 相似文献
963.
964.
Rebecca M. Montague-Drake David B. Lindenmayer Ross B. Cunningham John A. Stein 《Landscape Ecology》2011,26(10):1383-1394
We explored the effects of a purported ‘reverse keystone species’, the Noisy Miner (Manorina melanocephala) using a long-term, large-scale dataset. Specifically, we identify whether this aggressive bird affects the landscape distribution
patterns of other avifauna, by displacing them into, or restricting their distribution to, less productive areas, and in so
doing, adheres to ‘isoleg theory’. We sought to determine the effect of abundance of the Noisy Miner on the abundance of other
birds (individual species and groups), and determine whether that effect was consistent with varying site productivity, using
a negative binomial distribution with a logarithmic link function, and an offset variable to account for variations in search
effort. Relationships between abundance of Noisy Miners and habitat variables were examined using a Poisson distribution with
a logarithmic link function scaled for extra-variation (quasi-Poisson regression). We demonstrate that when Noisy Miner abundance
is low, many small passerine species are more abundant on high productivity sites. However, as Noisy Miner abundance increases,
small passerine abundance decreases, with this decrease most apparent on productive sites. The same patterns were not evident
for birds considered ‘non-competitors’ of the Noisy Miner. We identify that both site productivity and vegetation structure influence the abundance of the Noisy Miner. We reveal that the species increasingly tolerates ‘less
desirable’ habitat attributes with increasing site productivity. The preference of the Noisy Miner for productive areas is
likely to have deleterious impacts on the long-term survival and reproductive success of other Australian woodland bird species,
many of which have already undergone severe declines. 相似文献
965.
Jianguo Wu 《Landscape Ecology》2011,26(10):1345-1349
966.
The extent of noise and its impacts continues to grow globally indicating a different approach from regulating individual
noise sources is needed. We pose the argument that soundscapes, or the acoustic environment, should be managed as a common-pool
resource (CPR). Using CPR theory, we argue that soundscapes possess key features of CPRs: (1) multiple soundscape users, (2)
difficulty of exclusion, and (3) subtractability and degradation. Using Ostrom’s Social-Ecological Systems (SES) framework,
we describe the main elements of soundscapes to consider for their sustainable management. In order to assess noise issues
and challenges in managing national park soundscapes, we conducted interviews with U.S. National Park Service managers at
parks identified as having air tour overflight impacts. While most managers indicated that aircraft overflights posed the
most serious impacts to park resources and visitor experiences, the park units also experienced several other types of noise
impacts including traffic on park roads, park maintenance operations, and different types of motorized recreational vehicles.
Addressing single sources of noise is necessary, as is the case with air tour overflights, but we argue that a more comprehensive
approach is needed to protect park soundscapes. From this study several SES framework variables emerged that need to be addressed
for sustainable management, such as the lack of clear soundscape boundaries, availability of acoustic monitoring and data,
and the number and types of soundscape users. Based on CPR theory and using the SES framework, the challenges and a potential
new approach for sustainable management are discussed. 相似文献
967.
María Uriarte Charles B. Yackulic Yili Lim Javier A. Arce-Nazario 《Landscape Ecology》2011,26(8):1151-1164
There is a pressing need to understand the consequences of human activities, such as land transformations, on watershed ecosystem
services. This is a challenging task because different indicators of water quality and yield are expected to vary in their
responsiveness to large versus local-scale heterogeneity in land use and land cover (LUC). Here we rely on water quality data
collected between 1977 and 2000 from dozens of gauge stations in Puerto Rico together with precipitation data and land cover
maps to (1) quantify impacts of spatial heterogeneity in LUC on several water quality indicators; (2) determine the spatial
scale at which this heterogeneity influences water quality; and (3) examine how antecedent precipitation modulates these impacts.
Our models explained 30–58% of observed variance in water quality metrics. Temporal variation in antecedent precipitation
and changes in LUC between measurements periods rather than spatial variation in LUC accounted for the majority of variation
in water quality. Urbanization and pasture development generally degraded water quality while agriculture and secondary forest
re-growth had mixed impacts. The spatial scale over which LUC influenced water quality differed across indicators. Turbidity
and dissolved oxygen (DO) responded to LUC in large-scale watersheds, in-stream nitrogen concentrations to LUC in riparian
buffers of large watersheds, and fecal matter content and in-stream phosphorus concentration to LUC at the sub-watershed scale.
Stream discharge modulated impacts of LUC on water quality for most of the metrics. Our findings highlight the importance
of considering multiple spatial scales for understanding the impacts of human activities on watershed ecosystem services. 相似文献
968.
Positive effects of forest fragmentation,independent of forest amount,on bat abundance in eastern Ontario,Canada 总被引:1,自引:0,他引:1
While studies have found that bat abundance is positively related to the amount of forest cover in a landscape, the effects
of forest fragmentation (breaking apart of forest, independent of amount) are less certain, with some indirect evidence for
positive effects of fragmentation. However, in most of these studies, the variables used to quantify fragmentation are confounded
with forest amount, making it difficult to interpret the results. The purpose of this study was to examine how forest amount
and forest fragmentation independently affect bat abundance. We conducted acoustic bat surveys at the centers of 22 landscapes
throughout eastern Ontario, Canada, where landscapes were chosen to avoid a correlation between forest amount and forest fragmentation
(number of patches) at multiple spatial scales, while simultaneously controlling for other variables that could affect bat
activity. We found that the effects of forest amount on bat relative abundance were mixed across species (positive for Lasiurus borealis, negative for Perimyotis subflavus and Lasionycteris noctivagans). When there was evidence for an effect of forest fragmentation, independent of forest amount, on bat relative abundance,
the effect was positive (Myotis septentrionalis, Myotis lucifugus and Lasiurus borealis). We suggest that the mechanism driving the positive responses to fragmentation is higher landscape complementation in more
fragmented landscapes; that is, increased access to both foraging and roosting sites for these bat species. We conclude that
fragmented landscapes that maximize complementation between roosting and foraging sites should support a higher diversity
and abundance of bats. 相似文献
969.
970.
Luis J. Villanueva-Rivera Bryan C. Pijanowski Jarrod Doucette Burak Pekin 《Landscape Ecology》2011,26(9):1233-1246
In this paper we present an introduction to the physical characteristics of sound, basic recording principles as well as several
ways to analyze digital sound files using spectrogram analysis. This paper is designed to be a “primer” which we hope will
encourage landscape ecologists to study soundscapes. This primer uses data from a long-term study that are analyzed using
common software tools. The paper presents these analyses as exercises. Spectrogram analyses are presented here introducing
indices familiar to ecologists (e.g., Shannon’s diversity, evenness, dominance) and GIS experts (patch analysis). A supplemental
online tutorial provides detailed instructions with step by step directions for these exercises. We discuss specific terms
when working with digital sound analysis, comment on the state of the art in acoustic analysis and present recommendations
for future research. 相似文献