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1.
Thomas Ranius Petter Bohman Olof Hedgren Lars‐Ove Wikars Alexandro Caruso 《Ecography》2014,37(8):797-804
Despite increasing awareness of the theoretical importance of habitat dynamics on metapopulations, only a few empirical studies have been conducted. We aimed to increase our understanding of how patch size, dynamics and connectivity affect colonization–extinction dynamics and the occurrence patterns of a beetle (Stephanopachys linearis), which breeds only in burned trees, existing as dynamic habitat patches that have become rare in managed forest landscapes. We assessed species’ presence/absence twice in all known habitat patches (i.e. > 1 ha sites where forest fires had occurred during the previous 2–15 yr) in a 200 × 150 km region of central Sweden, dominated by managed boreal forest. Evaluated over six years, the colonization rate was 47% and the local extinction risk was 65%. Probability of colonization increased with patch size (number of suitable trees in a site) and connectivity to occupied patches within 30 km, and decreased with increasing time since fire. Local extinction risk decreased with habitat patch size but increased, unexpectedly, with connectivity. Occurrence increased with patch size and decreased with increasing time since fire. At a regional scale, S. linearis tracks the fire dynamics by colonising sites with burned trees and by becoming extinct at rates which make the species rare at sites where burnt trees are more than eight years old. In managed boreal forest landscapes, a large proportion of sites may be created by prescribed burning (in our study area: 82%), and consequently human decisions strongly affect the future amount of habitat for fire‐dependent species and its spatial distribution. Stephanopachys linearis uses burned sites more often if more trees are retained and, to some extent, if sites are concentrated in those parts of a region that already support high population densities of the species. 相似文献
2.
T. Wallenius L. Niskanen T. Virtanen J. Hottola G. Brumelis A. Angervuori J. Julkunen M. Pihlström 《Ecological Indicators》2010,10(6):1093-1101
Man has exploited land and forests in Western and Central Europe longer and more intensively than in Northern Europe and further east in Eurasia. We estimated forest naturalness and modelled expected biodiversity loss in seven different landscapes (2500 km2 each) in the Netherlands, Sweden, Finland, Poland, St. Petersburg (Western European Russia), Perm (Eastern European Russia), and Irkutsk (Central Siberia) across the distribution of Pinus sylvestris L. in Eurasia. Field inventories showed that the mean living tree volumes were relatively similar in the studied sites, but the volumes of dead wood differed greatly. In Irkutsk and Perm the volume of dead trees per ha was about 5–10 times larger than in Central and Western European regions. The studied forests were generally young in all regions except for Irkutsk, where about half of the study plots had trees older than 120 years. Signs of recent forest fires were found almost exclusively on Russian sites. According to Landsat satellite image-based land-cover classifications the amount of remaining forest habitat in the studied landscapes varied from 25% in the Netherlands to 93% in Irkutsk. Estimated by forest patch size and density of cut stumps, forests were also more fragmented and heavily managed in the western study landscapes compared to eastern ones. Based on species–area relationship functions, we calculated that the proportion of forest-dwelling species already extinct or expected to become extinct due to habitat loss ranges from 1–2% in Irkutsk to 13–24% in the Netherlands study landscape. For saproxylic species, which depend on dead wood, the extinction estimates were calculated based on remaining dead wood volume in the landscape. The modelled expected loss of saproxylic species ranged from 7–14% in Irkutsk to 35–58% in the Netherlands. 相似文献
3.
Unexpectedly diverse forest dung beetle communities in degraded rain forest landscapes in Madagascar
Tropical forests, which harbor high levels of biodiversity, are being lost at an alarming speed. Madagascar, a biodiversity hotspot, has lost more than half of its original forest cover. Most of the remaining forests are small fragments of primary and secondary forest with differing degrees of human impact. These forests, as well as coffee and fruit plantations, may be important in supporting the forest-dependent biodiversity in Madagascar but this has been little studied. In Madagascar, dung beetles, which offer important ecosystem services, are largely restricted to forests. We examined the ability of fragmented and degraded forests to support dung beetle diversity, compared to the large areas of primary forest in eastern Madagascar. We found a general trend of a reduction of species with a loss of forest connectivity. In contrast, a higher level of forest disturbance was associated with higher species diversity. In several sites of low-quality forest as many or more species were found as in less disturbed and primary forests. The average size of dung beetles was smaller in the lower quality localities than in the primary forests. These findings suggest that many forest dung beetles in Madagascar are better adapted to forest disturbance than earlier expected, although they require some level of connectivity to surrounding forest. 相似文献
4.
Information to guide decision making is especially urgent in human dominated landscapes in the tropics, where urban and agricultural frontiers are still expanding in an unplanned manner. Nevertheless, most studies that have investigated the influence of landscape structure on species distribution have not considered the heterogeneity of altered habitats of the matrix, which is usually high in human dominated landscapes. Using the distribution of small mammals in forest remnants and in the four main altered habitats in an Atlantic forest landscape, we investigated 1) how explanatory power of models describing species distribution in forest remnants varies between landscape structure variables that do or do not incorporate matrix quality and 2) the importance of spatial scale for analyzing the influence of landscape structure. We used standardized sampling in remnants and altered habitats to generate two indices of habitat quality, corresponding to the abundance and to the occurrence of small mammals. For each remnant, we calculated habitat quantity and connectivity in different spatial scales, considering or not the quality of surrounding habitats. The incorporation of matrix quality increased model explanatory power across all spatial scales for half the species that occurred in the matrix, but only when taking into account the distance between habitat patches (connectivity). These connectivity models were also less affected by spatial scale than habitat quantity models. The few consistent responses to the variation in spatial scales indicate that despite their small size, small mammals perceive landscape features at large spatial scales. Matrix quality index corresponding to species occurrence presented a better or similar performance compared to that of species abundance. Results indicate the importance of the matrix for the dynamics of fragmented landscapes and suggest that relatively simple indices can improve our understanding of species distribution, and could be applied in modeling, monitoring and managing complex tropical landscapes. 相似文献
5.
Biodiversity in agricultural landscapes: the ground beetle communities of woody uncultivated habitats 总被引:7,自引:0,他引:7
Agricultural landscapes can be defined as mosaics of landscape elements which are affected by farming practices. Woodland habitats, even though they are managed, are amongst the most stable elements of agricultural landscapes and can play a key role in the maintenance of biodiversity. This study of the ground beetle (carabid) communities of woodlands and woody linear features in a Scottish agricultural landscape shows that these habitats contribute significantly to the overall landscape diversity of these beetles. Communities in woods and hedgerows display the same species diversity and are both characterized by the presence of forest species. The main factors constraining carabid communities in both environments are the grazing intensity and, to a lesser extent, the type of soil. Heavily grazed locations are characterized by the occurrence of grassland species while forest species are restricted to ungrazed locations. At the landscape scale, the distribution of the forest species is limited by spatial isolation, indicating that there are insufficient functional links between woodland habitats in the study area. Isolation could be compensated for either by a better control of grazing so that linear features can be used as dispersal corridors for forest carabids or by planting more linear features and woods in the area. 相似文献
6.
Marja H. Bakermans Amanda D. Rodewald Andrew C. Vitz 《The Journal of wildlife management》2012,76(6):1225-1234
Managing for forest wildlife requires attention not only to quantity but quality of forests within the landscape. We examined the extent to which local structural attributes and landscape context of forest stands explained variation in density and reproductive success of mature forest birds across 12 sites in southeast Ohio, USA, 2004–2006. Results suggest that several structural characteristics influenced bird–habitat relationships in our study. Densities of 3 songbird species (i.e., ovenbird [Seiurus aurocapilla], cerulean warbler [Setophaga cerulea], and scarlet tanager [Piranga olivacea]) were positively related to canopy openness, which is usually a function of canopy gaps. Habitat attributes described by ground litter, understory density, and canopy height were positively associated with densities of ground (i.e., worm-eating warbler [Helmitheros vermivorum]), or shrub nesting species (i.e., Kentucky and hooded warblers [Geothlypis formosa and Setophaga citrina], respectively). Furthermore, the number of small trees likely drove the positive relationship between density of wood thrush (Hylocichla mustelina), a subcanopy nester. After accounting for temporal variability in daily nest survival rates, the odds of nest survival for all species increased 10.5% for every 1% increase in canopy openness and decreased 1.4% for each 5% increase in understory vegetation density. Habitat–nest survival relationships were not apparent at the level of the individual species. Our results suggest that structural attributes produced by increasing habitat heterogeneity may be necessary for conservation of forest bird communities. © 2012 The Wildlife Society. 相似文献
7.
Forest fragmentation can negatively affect plants if animal seed-dispersers become locally extinct in fragments. We conducted
a 2-year experiment to evaluate the importance of tree squirrels (Sciurus) as seed dispersers for Quercus, Carya, and Juglans, and to assess dispersal consequences in patches where fragmentation-sensitive eastern gray squirrels (Sciurus carolinensis) are absent. We accounted for fates of ∼15,700 seeds from five tree species in four exclosure treatments at 18 fragments
during a high (2003–2004) and low seed (2004–2005) year. Two treatments excluded Sciurus to mimic disperser loss. We sampled nut-tree seedling density at 259 sites across eight watersheds, half of which were too
fragmented to support S. carolinensis, but supported fragmentation-tolerant fox squirrels (Sciurus niger). Autumn-to-spring seed survival was low (∼1%) for all species during low seed production. During high seed production, survival
was higher for Juglans nigra (20%) and Carya ovata (16%) than for three Quercus species (∼4% for Quercus palustris and Quercus rubra in two exclosure types; ∼1% for Quercus alba in all treatments). Survival of J. nigra, C. ovata, and Q. rubra was ≥2.1–7.7 times higher for seeds in exclosures that Sciurus could access. Seed displacement distance was higher in the low seed than the seed-rich year, but the proportion of seeds
surviving to greater distances was higher in seed-rich years for all seed types except Q. rubra. This affirms the importance of masting to seed survival and dispersal, but also suggests an advantage to trees of producing
seed in non-mast years. Seedling densities were comparable in watersheds with and without S. carolinensis. These results demonstrate the importance of tree squirrels as dispersers of nut-bearing trees, but suggest that fragmentation
may not disrupt dispersal of certain species if losing S. carolinensis from disturbed landscapes is compensated for by fragmentation-tolerant fox squirrels (S. niger). 相似文献
8.
Bastian Schauer Manuel J. Steinbauer Lionel S. Vailshery Jörg Müller Heike Feldhaar Elisabeth Obermaier 《Biodiversity and Conservation》2018,27(4):853-869
Tree hollows are key structures in forest ecosystems constituting long-lasting habitats and nutritional resources for many saproxylic arthropod species. Due to diverse microhabitat structures and conditions in tree hollows, they can support a broad range of species. However, in the past intensive management practices in parts of Europe reduced the abundance of tree hollows, resulting in a decrease and endangerment of species specialised in this tree habitat. We investigated 40 beech trees with hollows in 2014 and a subset of 23 of these trees in 2015 in a managed forest landscape in Germany. Using emergence traps we collected 89 beetle species of which 33% were on the Bavarian Red List. We described the tree characteristics, physical hollow characteristics, and their surrounding environment investigating their influence on α-diversity of non-Red List and Red List species. Furthermore, we investigated spatial (between tree hollows) and temporal (same tree hollow but different years) β-diversity, considering the importance of turnover and nestedness components on β-diversity. α-Diversity decreased with increasing decomposition of wood mould and increased with increasing area of hollow entrance in both years. Additional characteristics differed between years and between non-Red List and Red List species. β-Diversity was related to diameter at breast height, number of surrounding tree hollows, area of hollow entrance and a temperature gradient. We found a higher species turnover than nestedness between tree hollows and between years, indicating highly dynamic beetle communities spatially as well as temporally. To support and maintain the diversity of saproxylic beetles inhabiting tree hollows, the heterogeneity of microhabitats is important and should be supported by maintaining the diversity of differently structured and sized tree hollows. 相似文献
9.
Ellen Andresen 《Journal of Insect Conservation》2008,12(6):639-650
Dung beetles (Scarabaeinae) are conspicuous components in most terrestrial ecosystems, performing important ecological functions
and services. Being sensitive to several types of disturbance, they have been successfully used as indicators of habitat change.
Dung beetle communities in tropical rainforests have been well studied, but considerably less information is available for
tropical dry forests. In this study I sampled dung beetles in two undisturbed habitats, deciduous forest and semideciduous
forest, and two disturbed habitats, secondary forest and open area habitat, in the Chamela-Cuixmala region of western Mexico.
Dung beetle species with high indicator value for each habitat were identified. Beetle abundance, observed species richness
and estimated species richness were similar in the three forest habitats, but significantly lower in the open area habitat.
A more detailed analysis of species-specific abundances in the three forest habitats revealed some differences. Transects
of one of the undisturbed habitats, the deciduous forest, were more similar to the non-adjacent transects of disturbed secondary
forest, than to the adjacent undisturbed semideciduous forest transects. Unlike studies in other tropical sites that have
found a decrease in equitability in Scarabaeinae assemblages between undisturbed forest and disturbed habitat (particularly
open habitats), in the Chamela-Cuixmala region all four habitats showed similar low equitability in community structure, with
two or three very dominant species. 相似文献
10.
11.
Inge van Halder Luc Barbaro Emmanuel Corcket Hervé Jactel 《Biodiversity and Conservation》2008,17(5):1149-1169
While the area of plantation forests continues to increase worldwide, their contribution to the conservation of biodiversity
is still controversial. There is a particular concern on the central role played by natural habitat remnants embedded within
the plantation matrix in conserving species-rich insect communities. We surveyed butterflies in maritime pine plantation landscapes
in south-western France in 83 plots belonging to seven habitat types (five successional stages of pine stands, native deciduous
woodlands and herbaceous firebreaks). The effect of plot, habitat and landscape attributes on butterfly species richness,
community composition and individual species were analysed with a General Linear Model (GLM), partial Canonical Correspondence
Analysis (CCA) and the IndVal method. The most important factors determining butterfly diversity and community composition
were the presence of semi-natural habitats (deciduous woodlands and firebreaks) at the landscape scale and the composition
of understorey vegetation at the plot scale. Pure effects of plot variables explained the largest part of community variation
(12.8%), but landscape factors explained an additional, independent part (6.7%). Firebreaks were characterized by a higher
species richness and both firebreaks and deciduous woodlands harboured species not or rarely found in pine stands. Despite
the forest-dominated landscape, typical forest butterflies were rare and mainly found in the deciduous woodlands. Threatened
species, such as Coenonympha oedippus and Euphydryas aurinia, were found in pine stands and in firebreaks, but were more abundant in the latter. In the studied plantation forest, the
conservation of butterflies depends mainly on the preservation of semi-natural habitats, an adequate understorey management
and the maintenance of soil moisture levels. 相似文献
12.
In forest fragments, rare habitats contribute to heterogeneity and may provide unique resources for frugivorous species like peccaries with spatially and temporally complex patterns of range use. This study examined seasonal habitat use by two sympatric peccary species ( Tayassu pecari and Tayassu tajacu ) in an Atlantic forest fragment on the plateau region of São Paulo state, Brazil. Previous studies showed that range use by T. pecari was highly nonrandom, and that both species persisted at population densities typical of larger forest fragments. To explain this, we quantified the use and availability of habitats and riparian zones with compositional analysis. Use by T. pecari was nonrandom with respect to availability. Habitat preferences were different during dry and wet seasons and corresponded closely with seasonal movements, core range and fruit use. Although aquatic habitats made up a small proportion of the herd home range, they were most preferred by T. pecari during both seasons. Headwater palmito Euterpe edulis swamps were most favored in the dry season, whereas swamps and marshes near larger streams were preferred in the wet season. Tayassu pecari preferred riparian zones <50 m from streams over drier zones. These habitats were important sources of fruits, travel routes and corridors between forest patches in the agricultural matrix. The least-preferred habitat of T. pecari during both seasons was disturbed forest edge dominated by bamboo. Habitat and riparian zone use were herd-specific for T. tajacu and related to habitat quality and composition where stable home ranges had been established. The persistence of viable peccary populations after 75 years of fragmentation-associated pressures is related to preservation of rare habitats and overall habitat diversity. Thus, T. pecari is an indicator of high habitat diversity in forest fragments and will function as an umbrella species when targeted for conservation. 相似文献
13.
Antoine Brin Lionel Valladares Sylvie Ladet Christophe Bouget 《Biodiversity and Conservation》2016,25(3):587-602
Ancient forests are of considerable interest for strategies for biodiversity conservation. However, in European forest landscapes fragmented and harvested for a long time forest continuity might be no longer a key driver for flying organisms such as saproxylic beetles. In a study based on paired samples (n = 60 stands, p = 180 traps) of ancient and recent forests, we investigated the effects of forest continuity on saproxylic beetle assemblages in two French regions. Mean species richness was significantly related with deadwood volume in ancient forests, but not in recent forests. This loss of relationship between assemblages and their environment suggests that dispersal limitation is at work, at least for some species. Forest continuity had a significant effect on mean species richness and on the mean number of common species, but not on rare species. Forest continuity had a significant effect on assemblage composition in one out of the four cases tested. In both regions, we identified species associated with either recent or ancient forests. Finally, mean body size of species was significantly smaller in recent forests compared with ancient ones, as was their tree diameter preference, despite a higher volume of large deadwood in recent forests. These results lend support to using forest continuity as a criterion to identify sites of conservation importance, even in highly fragmented landscapes. 相似文献
14.
Kurtzman CP 《FEMS yeast research》2007,7(6):1046-1063
Eleven new yeasts from forest habitats are described from nucleotide sequence analysis of the nearly entire large subunit rRNA gene, ITS1-5.8S-ITS2 rRNA gene, mitochondrial small subunit rRNA gene, and the cytochrome oxidase II gene. All are members of the Sugiyamaella clade. Three are heterothallic species of Sugiyamaella and eight species are assigned to Candida. The Sugiyamaella species are: Su. americana sp. nov., type strain NRRL YB-2067 (CBS 10352), mating type a, and isotype NRRL YB-4197 (CBS 10353), mating type alpha; Su. chiloensis sp. nov., type strain NRRL Y-17646 (CBS 8168), mating type a, and isotype NRRL Y-27101 (CBS 5927), mating type alpha, anamorph Ca. bertae; Su. japonica sp. nov., type strain NRRL YB-2788 (CBS 10354), diploid, NRRL YB-2764 (CBS 10355), mating type a, and NRRL YB-2799 (CBS 10356), mating type alpha. The Candida species with type strains are: Ca. boreocaroliniensis sp. nov. NRRL YB-1835 (CBS 10344), Ca. floridensis sp. nov. NRRL YB-3827 (CBS 10350), Ca. grinbergsii sp. nov. NRRL Y-27117 (CBS 5924), Ca. lignohabitans sp. nov. NRRL YB-1473 (CBS 10342), Ca. marilandica sp. nov. NRRL YB-1847 (CBS 10346), Ca. marionensis sp. nov. NRRL YB-1336 (CBS 10341), Ca. neomexicana sp. nov. NRRL YB-2450 (CBS 10349), and Ca. pinicola sp. nov. NRRL YB-2263 (CBS 10348). 相似文献
15.
Throughout the world, previously extensive areas of natural habitats have been degraded and fragmented, and improving habitat connectivity may help the long-term persistence of species, and their ability to adapt to climate changes. We focused on Borneo, where many remaining areas of tropical forest are highly fragmented, and we assessed the extent to which Protected Areas (PAs) protect highly-connected forest sites. We analysed remotely-sensed land cover data (0.86 km2 grid cell resolution) using ‘Zonation’ reserve design software, and we ranked grid cells (rank 0–1) according to forest extent and connectivity. PAs currently cover 9% of Borneo, but <20% of highly-connected cells (i.e. cells with Zonation ranks ≥0.9) lie within PAs. Approximately 65% of highly-connected cells were located above 400 m elevation, although >60% of Borneo’s total land area lies below 200 m and only 15% of highly-connected cells occurred in these low elevation areas. These findings were relatively insensitive to assumptions about species’ dispersal ability (within the range 1–20 km; representing relatively mobile animal species). The percentage of highly-connected grid cells within PAs could rise from <20 to >50% under proposed new PAs (including the ‘Heart of Borneo’ project), although many other highly-connected sites will remain unprotected. On-going land-use changes mean that existing PAs in lowland areas are likely to become increasingly isolated within inhospitable agricultural landscapes, and improving connectivity through reforestation and rehabilitation of degraded forest may be required to maintain the conservation value of these PAs in future. 相似文献
16.
Epiphytic macrolichens in managed and natural forest landscapes: a comparison at two spatial scales 总被引:2,自引:0,他引:2
To maintain biodiversity in managed forests we must understand how forestry affects various organisms across a wide range of spatial and temporal scales. We compared landscape structure, forest structure, and species richness and abundance of epiphytic macrolichens in three pairs of natural and managed boreal forest landscapes. Study landscapes (2500 ha) were located within and adjacent to three of the largest forest reserves in Sweden (Reivo, Muddus, Jelka). The structural heterogeneity within landscapes was higher in managed forests whereas within-stand structural heterogeneity was higher in natural landscapes. Species richness of macrolichens at the stand level (sample plot) was 23% higher in natural forests but there was no difference at the landscape level. Most (86%) of the common species were more frequent in natural landscapes. Lichen abundance (estimated by lichen litter) was two times higher in natural than in managed landscapes, 5.6 and 2.7 kg ha-1 forest (pooled data), respectively. Both species richness and abundance were negatively related to cutting level (number and basal area of cut stumps) and positively related to stand variables (stand age, stem density and basal area). Lichen-rich forest stands were more numerous but covered a smaller area and were more isolated in managed landscapes. This may in turn have important consequences for dispersal of lichen propagules to second-growth forests. In conclusion, the results suggest that effects of forestry on epiphyte diversity and abundance are strongly related to the spatial scale (stand or landscape). To enhance biodiversity in managed forests we must increase structural heterogeneity at the whole range of spatial and temporal scales. 相似文献
17.
We examined the distribution of tree species across five habitats in 69 small plots within a single watershed of the Gunung Palung National Park, West Kalimantan, Indonesia (GPNP). The spatially complex distribution and close proximity of habitats provided an opportunity to test habitat specificity of tree species across strong environmental gradients, in a situation where dispersal into ‘inappropriate’ habitat should not be a rare event. Habitat had a weak influence on community structure, although species diversity was lower in the alluvium and peat habitats. Association tests based on two randomization models (spatially independent and explicit) were used to examine habitat distribution of 55 ‘common’ and 142 ‘frequent’ taxa. The general patterns were similar in the two models but the interpretation of specific patterns depended greatly on assumptions about dispersal ability. A majority (67%) of the common species was significantly associated with a single habitat, while few were restricted to one habitat. A small proportion (16%) of the species appear to be habitat generalists. The peat habitat had the most profound effect on species distribution. Overall, a large amount of variation was found in the degree of habitat specificity, even within speciose groups. No obvious evolutionary or ecological correlates with degree of habitat specificity were found. These results suggest that a mixture of stochastic and deterministic processes determine species distribution even across strong environmental gradients. 相似文献
18.
Occurrence of epiphytic macrolichens in relation to tree species and age in managed boreal forest 总被引:2,自引:0,他引:2
For the maintenance of biodiversity some epiphytic macrolichens have been used to identify forests with high conservation value. To understand what these macrolichens indicate, we studied the relationships of tree species and age with the abundance of a set of 33 macrolichens (20 of them in use as indicator species) at 90 localities in a 150 km2 area in south-central Sweden.
We sampled the four most common tree species Scots pine Pinus sylvestris. Norway spruce Picea abies , birch Betula spp, and aspen Populus tremula for macrolichens at 0-2 m from the base. Of the 33 target species we found 17, six of them were indicators in use for this region. In 30, out of 40 tested, cases there was a positive relation between lichen abundance and age of the tree.
On all tree species the number of the studied lichen species increased with age. The colonisation rate of the species was fastest on birch. All species occurring on birch were also found on at least one of the coniferous trees, while aspen had six species not found on other trees. Pine and spruce with a slow growth rate had more signal lichen species than fast growing trees.
We could not detect a competitive situation between common and rare species as the most abundant or largest lichens did not exclude other species. The length of the longest fruticose lichen was positively correlated with the number of species on the tree. Shade had a negative effect on the number of species.
We conclude that the indicator macrolichens encountered in this study showed a preference for old trees or aspens. This result, and the low number of indicator species, points at the importance of promoting these trees for the preservation of biodiversity in the boreal forest. 相似文献
We sampled the four most common tree species Scots pine Pinus sylvestris. Norway spruce Picea abies , birch Betula spp, and aspen Populus tremula for macrolichens at 0-2 m from the base. Of the 33 target species we found 17, six of them were indicators in use for this region. In 30, out of 40 tested, cases there was a positive relation between lichen abundance and age of the tree.
On all tree species the number of the studied lichen species increased with age. The colonisation rate of the species was fastest on birch. All species occurring on birch were also found on at least one of the coniferous trees, while aspen had six species not found on other trees. Pine and spruce with a slow growth rate had more signal lichen species than fast growing trees.
We could not detect a competitive situation between common and rare species as the most abundant or largest lichens did not exclude other species. The length of the longest fruticose lichen was positively correlated with the number of species on the tree. Shade had a negative effect on the number of species.
We conclude that the indicator macrolichens encountered in this study showed a preference for old trees or aspens. This result, and the low number of indicator species, points at the importance of promoting these trees for the preservation of biodiversity in the boreal forest. 相似文献
19.
20.
We examine existing and developing approaches to balance biodiversity conservation and timber production with the changing
conservation roles of federal and nonfederal forest land ownerships in the US Pacific Northwest. At landscape scales, implementation
of the reserve-matrix approach of the federal Northwest Forest Plan in 1994 was followed by proposals of alternative designs
to better integrate disturbance regimes or to conserve biodiversity in landscapes of predominantly young forests through active
management without reserves. At stand scales, landowners can improve habitat heterogeneity through a host of conventional
and alternative silvicultural techniques. There are no state rules that explicitly require biodiversity conservation on nonfederal
lands in the region. However, state forest practices rules require retention of structural legacies to enhance habitat complexity
and establishment of riparian management areas to conserve aquatic ecosystems. Habitat Conservation Plans (HCPs) under the
US Endangered Species Act provide regulatory incentives for nonfederal landowners to protect threatened and endangered species.
A state-wide programmatic HCP has recently emerged as a multi-species conservation approach on nonfederal lands. Among voluntary
incentives, the Forest Stewardship Council certification comprehensively addresses fundamental elements of biodiversity conservation;
however, its tough conservation requirements may limit its coverage to relatively small land areas. Future changes in landscape
management strategies on federal lands may occur without coordination with nonfederal landowners because of the differences
in regulatory and voluntary incentives between ownerships. This raises concerns when potentially reduced protections on federal
lands are proposed, and the capacity of the remaining landscape to compensate has been degraded.
This paper was previously published in Biodiversity and Conservation, Volume 16(13) under doi: 相似文献