| 1. |
- Bruun, Hans Henrik, et al.
(författare)
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Effects of altitude and topography on species richness of vascular plants, bryophytes and lichens in alpine communities
- 2006
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 17:1, s. 37-46
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Tidskriftsartikel (refereegranskat)abstract
- Question: What is the relationship between species richness of vascular plants, bryophytes and macrolichens, and two important gradients in the alpine environment, altitude and local topography? Location: Northernmost Fennoscandia, 250-152 m a.s.l. corresponding to the range between timberline and mountain top. Methods: The vegetation was sampled in six mountain areas. For each 25 vertical metres, the local topographic gradient from wind-blown ridge to snowbed was sampled in quadrats of 0.8 m x 0.8 m. Patterns in species richness were explored using Poisson regression (Generalized Linear Models). Functional groups of species, i.e. evergreen and deciduous dwarf-shrubs, forbs, graminoids, mosses, hepatics and lichens were investigated separately. Results: Functional groups showed markedly different patterns with respect to both altitude and topography. Species richness of all vascular plants showed a unimodal relationship with altitude. The same was true for graminoids, forbs and lichens analysed separately, but forb richness peaked at Much higher altitudes than total richness. The richness of dwarf-shrubs decreased monotonically with altitude, whereas richness of mosses and liverworts showed an increasing trend. Significant interactions between altitude and local topography were present for several groups. The unimodal pattern for total plant species richness was interpreted in terms of local productivity, physical disturbance, trophic interactions, and in terms of species pool effects. Conclusions: Patterns in local species richness result from the action of two opposing forces: declining species pool and decreasing intensity of competition with altitude.
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| 2. |
- Alessi, Nicola, et al.
(författare)
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Ancient refugia and present-day habitat suitability of native laurophylls in Italy
- 2019
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Ingår i: Journal of Vegetation Science. - : WILEY. - 1100-9233 .- 1654-1103. ; 30:3, s. 564-574
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Tidskriftsartikel (refereegranskat)abstract
- Questions European native laurophyllous species are interesting for their biogeography and evolutionary history, as well as for their responses to global changes. We identified Italian native laurophylls on the basis of morphology, biogeographical history and ecological niche to study whether these species are in equilibrium with the present-day climate. Furthermore, we localized Quaternary refugia and areas of potential spread of native laurophylls using distribution patterns of realized and potential aggregations of native laurophylls, respectively. Location Italy. Methods We extracted data for 17 087 forest plots from a phytosociological database. Detrended Correspondence Analysis of these plots with overlay of climatic and environmental variables was performed to identify native laurophylls, i.e., evergreen broad-leaved species of late Tertiary radiation, occupying a warm and humid niche. Potential ranges of laurophylls were calculated using Beals' index of sociological favourability. The realized/potential range-size ratio was calculated for each single laurophyll to understand whether it is in equilibrium with the present-day climate. Distribution patterns of realized and potential aggregations of laurophylls were mapped. Results Ordination analysis provided a selection of 11 species as Italian native laurophylls. Most of them occupied less than half of their estimated potential range. Realized aggregations richest in native laurophylls were localized in the central Apennines. However, the Italian forests showed high potential for native laurophylls with the richest potential aggregations in the whole Apennines and in the southern Alps. Conclusions Most of the Italian native laurophylls showed non-equilibrium with the current climate, suggesting that late-Quaternary events could better explain their present-day distribution than on-going climate change. Furthermore, their refugia in central Italy suggest the persistence in sites with temperate climate during Quaternary environmental changes. The high suitability of Italian forests for laurophylls, along with global changes, suggests possible future spreading of these species.
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| 3. |
- Arellano, Gabriel, et al.
(författare)
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Tree death and damage: A standardized protocol for frequent surveys in tropical forests
- 2021
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Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- Tree mortality drives changes in forest structure and dynamics, community composition, and carbon and nutrient cycles. Since tropical forests store a large fraction of terrestrial biomass and tree diversity, improved understanding of changing tree mortality and biomass loss rates is critical. Tropical tree mortality rates have been challenging to estimate due to low background rates of tree death, and high spatial and temporal heterogeneity. Furthermore, the causes of mortality remain unclear because many factors may be involved in individual tree death, and the rapid decomposition of wood in the tropics obscures evidence of possible causes of tree mortality. We present a field protocol to assess tree mortality in tropical forests. The protocol focuses on the rapid, repeatable and inexpensive assessment of individual tree death and damage. The protocol has been successfully tested with annual assessments of >62,000 stems in total in several ForestGEO plots in Asia and the Neotropics. Standardized methods for the assessment of tree death and biomass loss will advance understanding of the underlying causes and consequences of tree mortality.
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| 4. |
- Asplund, Johan, et al.
(författare)
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The influence of tree-scale and ecosystem-scale factors on epiphytic lichen communities across a long-term retrogressive chronosequence
- 2014
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Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 25, s. 1100-1111
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Tidskriftsartikel (refereegranskat)abstract
- Questions: We tested the relationship between total cover, species richness and composition of epiphytic lichens on trunks of Betula pubescens and ecosystem retrogression (i.e. prolonged absence of major disturbance). We then investigated how the relationships changed when also accounting for tree-scale factors (aspect, height and bark characteristics) and ecosystem-scale factors (e. g. light transmission, tree species diversity and soil fertility).Location: Thirty forested islands in northern Sweden differing in fire history, which collectively represent a retrogressive chronosequence spanning ca. 5000 yr.Results: Total lichen cover responded negatively to long-term absence of major disturbance, but only at exposed positions on the tree trunk, indicating that lichen cover on substrates with more favourable microclimates is less susceptible to environmental change at the ecosystem scale. Further, although there was no overall effect of island size on lichen species richness, we did find a significant interactive effect between island size and height on trunk on species richness. This emerged because species richness decreased with retrogression for lichen communities at breast height, but showed a hump-shaped response to retrogression at the trunk base. Shifts in ecosystem properties with retrogression explained some of the variation in lichen community composition, but most of the variation could be explained by tree-scale factors, notably height on the trunk.Conclusions: While it has frequently been shown that lichens increase in abundance and richness during the first two or three centuries of succession, our results highlight that over a much longer time scale, encompassing soil aging and declining soil fertility, the lichen flora can be negatively affected. However, these effects are heavily mediated by tree-scale factors. These changes in the lichen community may be of potential importance for ecosystem processes and higher trophic level interactions driven by lichen communities.
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| 5. |
- Auffret, Alistair G., et al.
(författare)
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Grazing networks provide useful functional connectivity for plants in fragmented systems
- 2012
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Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 23:5, s. 970-977
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Tidskriftsartikel (refereegranskat)abstract
- Question To what extent does the movement of animals between fragmented habitat patches provide functional connectivity via endozoochorous seed dispersal? Location The Stockholm archipelago, Sweden. Methods We followed all movements of livestock between islands during one grazing season. After each movement, manure was collected and its seed content assessed through seedling emergence. Seedling data were then compared to vegetation surveys from the grazed islands with regard to functional traits. Results Light- and nitrogen-demanding locally abundant species, and those with relatively small and persistent seeds were more likely to be moved between islands. For quantitative traits, only a subset of the available trait ranges were dispersed, with extreme values left behind. Species apparently specialized to other means of dispersal emerged from the manure samples. Neither dispersed traits nor seed density changed with timing of movement, but seed richness and diversity both increased throughout the season. The subsets of endozoochorously-dispersed species in the established vegetation were more similar than non-dispersed subsets between islands linked by livestock. Conclusions Grazing networks contribute to the connectivity of the core species in the system, and could provide useful tools for grassland management in fragmented landscapes.
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| 6. |
- Backéus, Ingvar
(författare)
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Distribution and vegetation dynamics of humid savannas in Africa and Asia
- 1992
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 3, s. 345-356
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Tidskriftsartikel (refereegranskat)abstract
- A review is presented on the literature about the distribution of savannas in humid climates in Africa and Asia and their vegetation dynamics. Sections are devoted to African lowland and montane savannas (the latter divided into southern, eastern, western and northern African), Madagascar, Indian subcontinent, SE Asia and New Guinea. It is concluded that the extension of savannas under humid climatic conditions and the relation to the distribution of forests is a function of cultivation, grazing by domestic and wild animals, present and previous climate, geomorphology and soil characteristics. Once established, savannas are often maintained by fires, both natural and man-made.Montane savannas are generally brought about by man's clearing, cultivation and burning. Fire is a stochastic variable; it creates an ecotone sensu stricto (an environmentally stochastic stress zone) at the forest/savanna border. On the other hand, if geomorphology and soil are the determinants, the transition between forest and savanna would have the character of an ecocline (a gradient zone) with fundamentally different conditions.In humid African lowland climates forests expand into savannas if the latter are not maintained by man. Whether forests also expand in less humid climates is disputed. In montane areas forest expansion may be delayed on degraded soils and when diaspores are lacking
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| 7. |
- Backéus, Ingvar, et al.
(författare)
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Vegetation changes on formerly overgrazed hill slopes in semi-arid central Tanzania
- 1994
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 5, s. 327-336
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Tidskriftsartikel (refereegranskat)abstract
- Composition of hill slope vegetation was studied in a semi-arid part of upland Tanzania where all grazing had been banned for 12 yr. The hills had been severely overgrazed previously and suffered from heavy gully and sheet erosion. Eight vegetation types are described. Floristic gradients revealed by numerical ordination techniques were found to be related mainly to degree of erosion, soil type and succession. The more or less bare soil that prevailed after grazing had ceased is now covered by grassland, woodland and immature secondary forest. The grasslands are still characterized by early successional species and they will probably remain open grassland as long as frequent burning continues. Brachystegia woodlands may have developed during earlier periods when the field layer was sparse due to grazing. The grazing had reduced the frequency of fire which in turn promoted the establishment of Brachystegia spp. Secondary forests are believed to have developed mainly where fires were not frequent, particularly at higher altitudes.
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| 8. |
- Berglund, Håkan, et al.
(författare)
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Predictability of plant and fungal species richness of old-growth boreal forest islands
- 2001
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 12:6, s. 857-866
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Tidskriftsartikel (refereegranskat)abstract
- The fragmentation and deterioration of old-growth forest habitat by modern forestry have become a major threat to species diversity in Fennoscandia. In order to develop a conservation strategy for the remaining diversity it is essential to identify the existing diversity and to develop appropriate conservation and monitoring programs. For these purposes indicators of conservation value for administrative prioritization are required. This study examines the predictability of plant and fungal species richness on two spatial scales on 46 isolated old-growth forest islands (0.17-12 ha) in a forest-wetland mosaic. We explore (1) to what extent area, isolation and stand structure variables can explain the variation in species richness and (2) if richness patterns of individual species groups correlate. Isolation showed no relation to species richness. Area explained 50-70% of the variation in total species richness and was positively related to the density of crustose lichens and Red-list species in island interiors. Stand structure variables explained 28-66% of the residual variation in total species richness after controlling for island size, and 15-73% of the variation in density of species in island interiors. The highest predictability of species richness was found among substrate-specific fungi and Red-list species. Different stand structure variables were found to explain richness in the different species groups, and only among a few species groups species richness correlated. Thus, species richness of one single species group is unlikely to be a good indicator for total biodiversity. The results show that measurements of stand size and stand structure variables may be a strong complementary tool. and sometimes a substitute to extensive species inventories when one aims to estimate and monitor plant and fungal species diversity in old-growth Picea abies forests.
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| 9. |
- Biurrun, Idoia, et al.
(författare)
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Benchmarking plant diversity of Palaearctic grasslands and other open habitats
- 2021
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Ingår i: Journal of Vegetation Science. - Oxford : John Wiley & Sons. - 1100-9233 .- 1654-1103. ; 32:4
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Tidskriftsartikel (refereegranskat)abstract
- Journal of Vegetation Science published by John Wiley & Sons Ltd on behalf of International Association for Vegetation Science.Aims: Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location: Palaearctic biogeographic realm. Methods: We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m2 and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results: Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions: The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology. © 2021 The Authors.
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| 10. |
- Blume-Werry, Gesche, et al.
(författare)
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Proportion of fine roots, but not plant biomass allocation below ground, increases with elevation in arctic tundra
- 2018
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Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 29:2, s. 226-235
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Tidskriftsartikel (refereegranskat)abstract
- Questions: Roots represent a considerable proportion of biomass, primary production and litter input in arctic tundra, and plant allocation of biomass to above- or below-ground tissue in response to climate change is a key factor in the future C balance of these ecosystems. According to optimality theory plants allocate C to the above- or below-ground structure that captures the most limiting resource. We used an elevational gradient to test this theory and as a space-for-time substitution to inform on tundra carbon allocation patterns under a shifting climate, by exploring if increasing elevation was positively related to the root:shoot ratio, as well as a larger plant allocation to adsorptive over storage roots.Location: Arctic tundra heath dominated by Empetrum hermaphroditum close to Abisko, Sweden.Methods: We measured root:shoot and fine:coarse root ratios of the plant communities along an elevational gradient by sampling above- and below-ground biomass, further separating root biomass into fine (<1 mm) and coarse roots.Results: Plant biomass was higher at the lower elevations, but the root:shoot ratio did not vary with elevation. Resource allocation to fine relative to coarse roots increased with elevation, resulting in a fine:coarse root ratio that more than doubled with increasing elevation.Conclusions: Contrary to previous works, the root:shoot ratio along this elevational gradient remained stable. However, communities along our study system were dominated by the same species at each elevation, which suggests that when changes in the root:shoot ratio occur with elevation these changes may be driven by differences in allocation patterns among species and thus turnover in plant community structure. Our results further reveal that the allocation of biomass to fine relative to coarse roots can differ between locations along an elevational gradient, even when overall above- vs below-ground biomass allocation does not. Given the functionally different roles of fine vs coarse roots this could have large implications for below-ground C cycling. Our results highlight the importance of direct effects vs indirect effects (such as changes in plant community composition and nutrient availability) of climate change for future C allocation above and below ground.
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