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991.
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
992.
993.
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
994.
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
995.
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
996.
997.
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
998.
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
999.
Robert Brus Dalibor Ballian Peter Zhelev Marija Pandža Martin Bobinac Jane Acevski Yannis Raftoyannis Kristjan Jarni 《European Journal of Forest Research》2011,130(4):657-670
We examined leaf and mature seed cone variation of Juniperus oxycedrus L. subsp. oxycedrus in 12 natural populations across the species range in the Balkan Peninsula. We measured 10 morphological traits from a minimum
of 100 leaves in each of 190 individuals, and two morphological traits from 30–50 seed cones in each of 94 females. High phenotypic
variation was found, but no geographical structure or cline across populations was detected for any of the studied traits.
Mean values of comparable leaf and cone morphological traits did not differ considerably from values reported elsewhere. Gender
dimorphism in leaf morphology was detected, but it was not distributed uniformly throughout the studied area. An ANOVA model
with both nested and crossed effects revealed that the largest proportion of the total variation was, as expected, contained
within populations, partly as among-tree variation (18–47%, depending on the trait) and partly as within-tree variation (33–77%),
which was remarkably high. Gender dimorphism explained only 0–3% of the total variation. Differences among populations (2–23%)
were significant for all studied traits except one; however, PCA showed no clear geographical differentiation of the studied
populations. This lack of phylogeographical structure may be the consequence of repeatedly occurring colonisation-retreat
scenarios and suggests the existence of several small refugial populations scattered over a large part of the Balkan Peninsula
in the Pleistocene. Further research including palaeobotanical and molecular genetic studies will be needed to better understand
the forces that shaped current variation patterns of J. oxycedrus L. subsp. oxycedrus in the Balkan Peninsula. 相似文献
1000.
Bao-Li Qiu Fang Dang Shao-Jian Li Muhammad Z. Ahmed Feng-Liang Jin Shun-Xiang Ren Andrew G. S. Cuthbertson 《Journal of pest science》2011,84(4):419-427
The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a widely distributed and destructive agricultural pest on various host plants. The
biology of two biotypes of B. tabaci: the invasive B and a new defined Cv biotype, on a range of host plants (hibiscus, laurel, poinsettia, collard, cucumber
and tomato) were studied in the laboratory. Results revealed that the developmental periods of the B biotype immatures were
not significantly different on the tested host plants except those between laurel and collard. The Cv biotype immatures developed
significantly slower on cucumber and tomato than on the other plants. B. tabaci B biotype had the highest survivorship on collard (68.55%), and the lowest on laurel (33.24%), while the Cv biotype had the
highest and lowest survivorships on laurel (61.63%) and tomato (36.74%). Host plants did not significantly affect the pre-ovipostion
period regardless of biotype. The longest averaged longevity and highest fecundity of B biotype were both recorded on collard:
25.15 days and 143.0 eggs. The highest fecundity of Cv biotype was 196.49 eggs on laurel and its longest longevity was on
hibiscus (19.62 days). The intrinsic rate of natural increase (r
m) of B biotype on the three vegetables were all higher than those on the three ornamentals whereas the r
m of Cv biotype on the three ornamentals were all higher that those on the three vegetables. Our research indicates that B. tabaci B and Cv biotypes have different host plant suitabilities. The three tested vegetables were more suitable for B biotype while
the three tested ornamental plants were more suitable for Cv biotype. The potential mechanism for the different suitability
of B and Cv biotypes on various host plants is also discussed. 相似文献