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951.
Modelling dynamics of ecosystem services basket in Mediterranean landscapes: a tool for rational management 总被引:1,自引:1,他引:0
Natural ecosystems are life-supporting systems providing diverse ecosystem services (ESs) and benefits to human societies:
e.g., food and clean water, recreation opportunities or climate regulation. The contribution of natural and semi-natural ecosystems
to the provision of such services depends to a large extent on vegetation structure and composition, which, in turn, change
as a result of interactions between human decisions about land management, and spontaneous biological and environmental processes.
Rational management of these dynamic ecosystems requires an ability to predict short- and long-term effects of management
decisions on the desired ESs. The vegetation then contributes to, and modifies, the products and services obtained from the
land. We applied mathematical modeling to study these complex relationships. We developed a model for a Mediterranean ecosystem
which predicts the dynamics of multiple services in response to management scenarios, mediated by vegetation changes. Six
representative ESs representing different groups were selected, based on available scientific information, for a detailed
study: (1) density of geophytes, (2) potential contribution to honey production, (3) energy density of fleshy fruits foraged
by birds, (4) forage for goats, (5) forage for cattle, and (6) carbon retention in woody plants. Mean contributions to each
service by different vegetation cover types were estimated, and the overall service provided by the site was calculated as
a weighted mean of these contributions. Services were measured in their appropriate units and subsequently standardized to
a percentage of the maximum value observed in the study area. We attempted to combine all studied ESs, despite their different
nature, into one “ESs basket”. This paper presents the dynamics of simulated vegetation composition and values of services
in response to management scenarios involving grazing, fire and their combinations. Our approach can help land managers to
evaluate alternative management scenarios by presenting the “services basket” obtained from the entire managed area. 相似文献
952.
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
953.
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
954.
955.
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
956.
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
957.
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
958.
959.
Populations at the periphery of a species’ range often show reduced genetic variability within populations and increased genetic
divergence among populations compared to those at the core, but the mechanisms that give rise to this core-periphery pattern
in genetic structure can be multifaceted. Peripheral population characteristics may be a product of historical processes,
such as founder effects or population expansion, or due to the contemporary influence of landscape context on gene flow. We
sampled collared lizards (Crotaphytus collaris) at four locations within the northern Flint Hills of Kansas, which is at the northern periphery of their range, to determine
the genetic variability and extent of genetic divergence among populations for ten microsatellite loci (n = 229). We found low genetic variability (average allelic richness = 3.37 ± 0.23 SE; average heterozygosity = 0.54 ± 0.05
SE) and moderate population divergence (average FST = 0.08 ± 0.01 SE) among our sample sites relative to estimates reported in the literature at the core of the species’ range
in Texas. We also identified differences in dispersal rates among sampling locations. Gene flow within the Flint Hills was
thus greater than for other peripheral populations of collared lizards, such as the Missouri glade system where most of the
mesic grasslands have been converted to forest since the last glacial retreat, which appears to have greatly impeded gene
flow among populations. Our findings signify the importance of considering landscape context when evaluating core-peripheral
trends in genetic diversity and population structure. 相似文献
960.
Thomas Ledermann 《European Journal of Forest Research》2011,130(4):521-531
In this study, a non-linear model was developed that predicts the five-year change of height to crown base (HCB) of Norway
spruce (Picea abies [L.] Karst.). Data were available from the Austrian National Forest Inventory and comprised 2,419 trees from 1,637 permanent
sample plots measured during 1981 and 2002. The dynamic model explained 36% of the variation in the observed change of HCB.
It is well behaved and meets biological expectations. Based on five independent data sets, the predictive ability of the new
dynamic model was compared to an already existing static crown ratio model. For this comparison, the models were applied as
follows: the new ∆ HCB model was used to predict the change in HCB directly. For the semi-dynamic method, the static model
was applied at the end and at the start of the growth period to obtain two estimates of HCB. The difference of these two estimates
was then added to the initial HCB. For the static method, the model was only applied at the end of the prediction period to
obtain the new estimate of HCB. Except for one plot, the new ∆ HCB model yielded the smallest BIAS and the highest precision,
followed by the semi-dynamic and the static method. Because the independent data sets cover a broad range of age classes and
thinning regimes, the validation results also indicate that the new ∆ HCB is robust and the effect of stand management is
adequately represented. 相似文献