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1.
The organic matter reserves and the soil humus state are assessed in three types of landscapes of the middle taiga (Karelia). Peat soils are the main organic matter reservoir. Hence, the greater their area, the higher the organic matter reserves in a particular landscape. The organic matter stocks in the group of semihydromorphic and hydromorphic soils clearly correlate with the degree of their waterlogging. The distribution of organic matter reserves within these soils depends on the ratio between the areas of boggy forests and open mires. The forest supporting quality of the soil is related to the organic matter composition and parent rock (the properties of the soil mineral horizons) rather than to the organic matter stocks. The data obtained may be used for assessing the forest supporting qualities of the soils and the basis for estimating the carbon budget in the landscapes.  相似文献   

2.
From 420 records of ethnic locations and movements since 2000 B. C., we computed vectors describing the proportions which peoples of the various European language families contributed to the gene pools within 85 land-based 5 × 5-degree quadrats in Europe. Using these language family vectors, we computed ethnohistorical affinities as arc distances between all pairs of the 85 quadrats. These affinities are significantly correlated with genetic distances based on 26 genetic systems, even when geographic distances, a common causative factor, are held constant. Thus, the ethnohistorical distances explain a significant amount of the genetic variation observed in modern populations. Randomizations of the records by chronology result in loss of significance for the observed partial correlation between genetics and ethnohistory, when geography is held constant. However, a randomization of records by location only results in reduced significance. Thus, while the historical sequence of the movements does not seem to matter in Europe, their geographic locations do. We discuss the implications of these findings. © 1993 Wiley-Liss, Inc.  相似文献   

3.
Thalli of the intertidal Phaeophyte Fucus spiralis L. and the subtidal Chlorophyte Ulva olivascens Dangeard were exposed to artificial UV-A, UV-B and photosynthetically active radiation (PAR) by combination of PAR + UV-A + UV-B (PAB), PAR + UV-A (PA) and PAR (P) treatments. UV-A enhanced photosynthesis and stimulated carbonic anhydrase (CA) and nitrate reductase (NR) in F. spiralis whilst PAR only had an inhibitory effect in this species. U. olivascens suffered chronic photoinhibition in all the treatments as evidenced by reduced maxima photosynthesis (Pmax) and photosynthetic efficiency (α). Non stimulatory effect was observed upon CA and NR in this species. Our results showed that artificial UV radiation triggered opposite responses in both species. We suggest that differences shown by both species might be related to their location in the rocky shore and their ability to sense UV. We propose that the ratio UV:PAR acts as an environmental signal involved in the control of photosynthesis as shown by pronounced inhibition in samples exposed to only PAR. We also suggest that UV-regulated photosynthesis would be related to carbon (C) and nitrogen (N) cycles, regulating feedback processes that control C and N assimilation.  相似文献   

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An essential pilot study was designed to quantify observer heterogeneity and to compare observation methods for the detectability of forest birds in stands of Eucalyptus and Pinus radiata forest as a basis for a major research project on habitat fragmentation near Tumut, southern New South Wales. Twelve experienced observers participated in the investigation. Point interval counts, zig-zag walks and strip transects were used to count birds in both eucalypt and pine forests. The 65 species of birds recorded in the study were assigned to one of nine groups classified by a set of attributes that characterized bird detection by field observers (e.g. body size, colour and calling patterns). Observer heterogeneity varied between groups of birds and was most apparent for small birds foraging in low shrubs (species such as the white-browed scrub wren, assigned to group 2), frequent calling, active birds (species such as the golden whistler, assigned to group 7), and midstorey, undercanopy foragers with distinctive behaviour (species such as the grey fantail assigned to group 4). For bird groups 2, 4 and 7, additional variability due to observer differences resulted in an average increase of ~ 40% in the width of a 95% confidence interval for the logarithm of bird abundance generated from a 20 minute count. Our analysis shows that taking the average of counts obtained by two or more observers would negate the increase in variance of counts due to observer heterogeneity. Few differences between methods of field observation were found. However, for frequent calling, active birds (group 7) there was evidence that more birds were heard using the point interval count method. Our study clearly demonstrated a need to either control for observer differences or to assign at least two observers to individual sites when designing bird surveys for comparative studies. Failure to do so will result in a decrease in precision of bird counts.  相似文献   

6.
Models of Mobile Animal Populations (MAP models) simulate long-term land use changes, population trends and patterns of biological diversity on landscapes of 103-105 ha. MAP models can incorporate information about past land-use patterns and management practices and can project future patterns based on management plans. We illustrate this approach with an example of how implementation of a U.S. Forest Service management plan at the Savannah River Site in South Carolina, U.S.A., might influence population trends of Bachman's Sparrow Aimophila aestivalis, a relatively rare and declining species in southeastern pine forests. In this case, a management plan, largely designed to improve conditions for an endangered species, Red-cockaded Woodpecker Picoides borealis, may have a negative impact, at least in the short term, on another species of management concern, Bachman's Sparrow.
In a parallel processing version of the MAP models, a single landscape that would ordinarily be too large or detailed to be simulated on a single computer is subdivided into a number of smaller landscapes, and each landscape is simulated in parallel, either on a single multi-tasking machine or on a group of networked machines. With this approach we are attempting to determine just how large a landscape must be before the dynamics of a population within it are more or less independent of factors beyond the landscape boundaries.  相似文献   

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Tissue-resident macrophages play an important role in defense against pathogens and perform key functions in organ homeostasis, innate and adaptive immunity. Tissue macrophages originate from blood monocytes that infiltrate virtually every organ in the body. Macrophages in different tissues share many characteristics, including their ability to migrate, phagocytose particles, metabolize lipids and present antigens. Morphologically they are quite heterogeneous, and some distinct functions have been reported. The gene expression profile of macrophages is reflective of both their shared and distinct biological functions. Here, we show that macrophages from murine spleen, liver and peritoneum display dramatically different expression profiles. Clusters of genes were found to represent unique biological functions related to adhesion, antigen presentation, phagocytosis, lipid metabolism and signal transduction. Some gene families, such as integrins, are differentially expressed among the macrophages resident in different tissues, suggesting that the tissue of residence influences their biological function.  相似文献   

10.

Background

Balancing animal conservation and human use of the landscape is an ongoing scientific and practical challenge throughout the world. We investigated reproductive success in female greater sage-grouse (Centrocercus urophasianus) relative to seasonal patterns of resource selection, with the larger goal of developing a spatially-explicit framework for managing human activity and sage-grouse conservation at the landscape level.

Methodology/Principal Findings

We integrated field-observation, Global Positioning Systems telemetry, and statistical modeling to quantify the spatial pattern of occurrence and risk during nesting and brood-rearing. We linked occurrence and risk models to provide spatially-explicit indices of habitat-performance relationships. As part of the analysis, we offer novel biological information on resource selection during egg-laying, incubation, and night. The spatial pattern of occurrence during all reproductive phases was driven largely by selection or avoidance of terrain features and vegetation, with little variation explained by anthropogenic features. Specifically, sage-grouse consistently avoided rough terrain, selected for moderate shrub cover at the patch level (within 90 m2), and selected for mesic habitat in mid and late brood-rearing phases. In contrast, risk of nest and brood failure was structured by proximity to anthropogenic features including natural gas wells and human-created mesic areas, as well as vegetation features such as shrub cover.

Conclusions/Significance

Risk in this and perhaps other human-modified landscapes is a top-down (i.e., human-mediated) process that would most effectively be minimized by developing a better understanding of specific mechanisms (e.g., predator subsidization) driving observed patterns, and using habitat-performance indices such as those developed herein for spatially-explicit guidance of conservation intervention. Working under the hypothesis that industrial activity structures risk by enhancing predator abundance or effectiveness, we offer specific recommendations for maintaining high-performance habitat and reducing low-performance habitat, particularly relative to the nesting phase, by managing key high-risk anthropogenic features such as industrial infrastructure and water developments.  相似文献   

11.
Journal of Mathematical Biology - Conditions for population persistence in heterogeneous landscapes and formulas for population spread rates are important tools for conservation ecology and...  相似文献   

12.
Landscapes are complex objects often showing self-similar properties. For example, some power law exponents and fractal dimensions have been extensively used as global metrics for describing spatial arrangements of landscape land covers. This paper presents some newly found invariance properties for rural landscapes, with the hope to prepare further theory capable to link these properties mechanistically with generating processes. For this purpose, I propose a new surface-pattern analysis computing heterogeneity metrics into moving windows in a specific way. This generic method provides Multiscale Heterogeneity Maps (MHMs) and Heterogeneity Profiles (HPs) of almost any kind of landscape. Six landscapes, covering a wide range of observed mosaics have been analyzed by this way: four of them exhibit strong self-similar evenness (diversity) heterogeneity over two orders of magnitude with an apparent universality of the power law exponents (γ = ?0.19 ± 0.02). Such landscape self-organization is interpreted in terms of spatial arrangements of numerous land covers and fine scale patchy mosaics. This study suggests that most of terrestrial landscapes could exhibit power law behaviors in terms of evenness heterogeneity and could be the result of a hidden optimization of ecological and/or socio-economic processes.  相似文献   

13.
One and a half centuries after Darwin visited Chiloe Island, what he described as "…an island covered by one great forest…" has lost two-thirds of its forested areas. At this biodiversity hotspot, forest surface is becoming increasingly fragmented due to unregulated logging, clearing for pastures and replacement by exotic tree plantations. Decrease in patch size, increased isolation and "edge effects" can influence the persistence of forest species in remnant fragments. We assessed how these variables affect local density for six forest birds, chosen to include the most important seed dispersers (four species) and bird pollinators (two species, one of which acts also as seed disperser), plus the most common insectivore (Aphrastura spinicauda). Based on cue-count point surveys (8 points per fragment), we estimated bird densities for each species in 22 forest fragments of varying size, shape, isolation and internal-habitat structure (e.g. tree size and epiphyte cover). Bird densities varied with fragment connectivity (three species) and shape (three species), but none of the species was significantly affected by patch size. Satellite image analyses revealed that, from 1985 to 2008, forested area decreased by 8.8% and the remaining forest fragments became 16% smaller, 58-73% more isolated and 11-50% more regular. During that period, bird density estimates for the northern part of Chiloé (covering an area of 1214.75 km(2)) decreased for one species (elaenia), increased for another two (chucao and hummingbird) and did not vary for three (rayadito, thrust and blackbird). For the first three species, changes in patch features respectively exacerbated, balanced and overcame the effects of forest loss on bird population size (landscape-level abundance). Hence, changes in patch features can modulate the effect of habitat fragmentation on forest birds, suggesting that spatial planning (guided by spatially-explicit models) can be an effective tool to facilitate their conservation.  相似文献   

14.
Coupling habitat models based on GIS and on ground variables could help identify suitable areas (by means of landscape models obtained by GIS variables) to concentrate management actions for species’ conservation. In this study, the habitat requirements of Lesser Greys (LGS) and Woodchat Shrikes (WS), two threatened farmland bird species declining in Europe, were assessed in Apulia (south-eastern Italy) by means of binary logistic regression at two different levels: landscape (using GIS-measured variables); and, territory (using ground-measured variables) scales. The LGS occurrence at landscape scale was correlated to steppe-like areas and cereal crops. At the territory level, significant effects were detected for deciduous forests and the presence of isolated trees and shrubs. The WS occurrence at landscape scale was promoted by steppe-like areas and cereal crops, whereas, at the territory level significant effects were detected for steppe-like areas positively and suburban areas negatively. The landscape model was extrapolated to the entire region. Within highly suitable areas (occurrence probability higher than 0.66 according to the landscape model), we measured average habitat features and compared them with the optimal mosaic depicted by the territory level models. This allowed us to give spatially explicit and site-specific management recommendations for these two threatened species. LGS will mostly benefit from an increase in isolated shrubs and trees; whereas for WS, the most widespread recommendations are to increase steppe-like habitat and to prevent further urbanisation.Coupling “coarse” landscape models with the species ecology provided by fine-scaled models can integrate relevant information on species potential distribution and territory level requirements, making planning fine-tuned habitat management (within potentially suitable landscapes) in a spatially explicit way possible.  相似文献   

15.
Changes in bird populations as criteria of environmental changes   总被引:1,自引:0,他引:1  
Järvinen, O. and Väisänen, R. A. 1979. Changes in bird populations as criteria of environmental changes. – Holarct. Ecol. 2: 75-80.
Birds are a powerful tool of environmental monitoring, on account of their ecological diversity. Because of this, bird populations seem best suited for monitoring biological, possibly non-linear effects of specified environmental changes, such as habitat modification, and for general monitoring aimed at detecting unexpected environmental changes as they occur. Because many population changes have multiple causes, monitoring specific environmental changes is most rewarding if birds are grouped by e.g. habitat, major strategy (e.g. resident vs. migrant species), or feeding guild. A blueprint for a Nordic monitoring system based on breeding land birds is presented. Local trends may be atypical, and representative coverage of the major habitats in large areas should thus be ensured. As annual population fluctuations usually give little information in environmental monitoring, long-term projects are necessary. The line transect method seems applicable to many monitoring purposes, as it is rapid, inexpensive, relatively accurate, and suitable for sampling the northern terrestrial biota of the Holarctic region, probably including the temperate deciduous forests.  相似文献   

16.
When birds settle in new environments, they may encounter different suites of nest-predators, resulting in strong selection to nest in novel locations. An important axis of variation is in height of nest placement, because off-ground nests are likely to be subject to different predation pressures than on-ground nests. In their native habitats, i.e. temperate montane forest, dark-eyed juncos Junco hyemalis predominantly nest on the ground. A population of juncos became established on the urban campus of the Univ. of California at San Diego in the early 1980s, and now has a relatively high frequency (∼20%) of off-ground nests. Off-ground nesting is associated with strong fitness benefits: based on returns from 579 nests, an egg laid off the ground has ∼80% higher chance of producing a recruit to the next generation than one laid on the ground. In addition, some nests were occasionally re-used by ∼10% of females and off-ground nests were more likely to be re-used. Many females that bred off-ground also built an on-ground nests and we did not detect an association in nest site positions of mothers and daughters, implying low heritability of this novel nest placement trait. By contrast, certain territories consistently had on-ground nests irrespective of the identity of the breeding female. We suggest that a limitation of suitable off-ground nest sites for a species predominantly adapted to on-ground nesting greatly slows the rate of evolution of this trait.  相似文献   

17.
ABSTRACT

Capsule: Parent body colouration and nesting habitat may influence nest predation risk and, therefore, influence parental decisions on offspring care.

Aims: To investigate the adaptiveness of bird colouration under two different habitat and light conditions.

Methods: We used painted polyurethane dummies to simulate parental presence near nests, where some dummies were red, and others were cryptic brown. We placed artificial nests on trees in open and forested areas, along with two quail eggs and parental dummies.

Results: The results showed major predation on nests of the open area, however, we found no significant effect of parent colour on nest predation.

Conclusion: We suggest that the costs involved with nest site selection may overcome the costs of colouration in species that occur in these environments.  相似文献   

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19.
We estimated nesting success of a breeding bird assemblage in the central Monte Desert in four breeding seasons (1995–1999). We analyzed the effect of year, period within the breeding season, nest type, and nest location on daily survival rates (DSR). Averaged nesting success of passeriforms in natural habitats was very low (<20% on average, n=12 species). DSR tended to be lower during the egg-laying stage in Furnariidae, Rhinocryptidae, Mimidae, and Emberizidae. Tyrannidae had the highest DSR for all nesting stages and Emberizidae the lowest. Predation was the main cause of nest failure (>90% on average, n=12 species). DSR differed among years, being higher in the driest year (1995) and lower in the most humid year (1997). Nests initiated in the first half of the breeding season had higher DSR than those initiated in the second half. Closed nests had similar survival rates to open nests. DSR differed according to species of plant that supported the nest. Nest predation in the central Monte Desert may be an important selective pressure in birds' life history, which is in accordance with other results for South American temperate birds.  相似文献   

20.
Summary The paper reports results of a long-term (1964–1974) investigation on permanent study sites in natural forest ecosystems of the Tilio-Carpinetum and the Pino-Quercetum in the Bialowieza Forest. The influence of decaying logs and root craters was investigated. It was found that the main causes of uprooting were the spring and autumn winds. Wind direction and the position of logs lying on the ground are correlated. Picea is most susceptible to uprooting by winds. Almost one half of the trees of this species are alive at the moment of uprooting.By mapping changes in the distribution of uprooted trees on a permanent area in time, a balance of the change over in a 10-year period was determined. It appeared that the decomposition is slower than accumulation. From this, it was concluded that the stand is in a phase of natural thinning. In the study site, compartments were disinguished with various degrees of change in the number of uprooted trees, and the consequences of differentiation and constant transformation of the biotope and biocenosis by the occurrence of uprooted trees and by their decay are described.Nomenclature of species follows Flora Europaea.Contribution to the Symposium of the Working Group for Succession Research on Permanent Plots, held at Yerseke, the Netherlands, October 1975.  相似文献   

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