scholarly journals Complex Changes in Plant Communities across a Subarctic Alpine Tree Line in Labrador, Canada + Supplementary Appendix Table (See Article Tools)

ARCTIC ◽  
2015 ◽  
Vol 68 (4) ◽  
pp. 500 ◽  
Author(s):  
Andrew J. Trant ◽  
Keith Lewis ◽  
Brittany H. Cranston ◽  
Julia A. Wheeler ◽  
Ryan G. Jameson ◽  
...  
Keyword(s):  
Plant Communities ◽  
Species Turnover ◽  
Abiotic Factors ◽  
Elevation Gradient ◽  
Alpine Tundra ◽  
Tree Cover ◽  
Tree Line ◽  
Forest Tundra ◽  
Abrupt Changes ◽  
Species Establishment

As climate warms, abiotic factors, as well as plant community and biodiversity structure, may constrain or promote the movement of ecotone boundaries. Our study sought to examine how plant communities change across the tree-line ecotone of the Mealy Mountains in Labrador, Canada. We established eight transects (50–100 m in length) along an elevation gradient in three tree-line zones (forest, forest-tundra, and alpine-tundra) and recorded all species and cover of vegetation in contiguous 1 × 1 m quadrats. Companion abiotic parameters of nutrients and soil temperature were also measured. The absence of abrupt changes in important soil nutrients and growing season temperatures suggests that these factors do not limit tree species establishment beyond the current tree line. Vegetation cover and richness, however, were highly variable and in some cases changed non-linearly across the tree-line ecotone. Tree cover and species density generally decreased with elevation, while some field layer species (< 25 cm in height) increased; the latter change seems to be influenced by ground shrubs rather than herbaceous species. As expected, transects separated by the greatest difference in elevation were the least similar (higher beta diversity/species turnover); however, species turnover between the forest and forest-tundra transects was higher than it was between forest-tundra and alpine-tundra transects, even though the latter were separated by a greater elevation. Community structure and species turnover vary greatly across a tree line with the greatest differences between the forest and the forest-tundra, suggesting a biotic or abiotic barrier. While our ability to predict how the tree line will respond to continued climate change is complicated by these patterns in plant communities, the potential barriers investigated and others identified will be a useful focus for future studies.

scholarly journals Vegetation dynamics under non-strong agricultural impact (by the example of Oktyabrsk village environs in the Uchalinskiy District of the Republic of Bashkortostan)

2021 ◽  
Vol 10 (1) ◽  
pp. 121-127
Author(s):  
Nazar Nikolayevich Nazarenko ◽  
Svetlana Yuryevna Batyusheva
Keyword(s):  
Plant Communities ◽  
Vegetation Dynamics ◽  
Vascular Plants ◽  
Abiotic Factors ◽  
Pasture Digression ◽  
Plant Associations ◽  
Republic Of Bashkortostan ◽  
Principal Factors ◽  
The Republic ◽  
Agricultural Impact

Vegetation and its biotopes that are transitional between ruderal and natural ones have been researched in Oktyabrsk village environs (Uchalinskiy District of the Republic of Bashkortostan). The studied vegetation is characterized by rather low biodiversity values and high values of dominance 56 species of vascular plants are identified, 10-species plant communities with 23 clear identified dominant and co-dominant species prevail. Ruderal species are dominant and co-dominant for the majority of plant communities. Fifteen plant associations and specific biotopes have been defined by multivariate statistics methods. The identified associations are phytometers for detected principal abiotic factors. The detected associations form ordination series the authors have identified three biotopical centers (ruderal, birch forest and steppe), three biotopical series and three coenotic series, which are associated with high and temperate pasture loading levels and pasture digression series, forming an integrated succession system of the studied territory. It has been established that principal factors of associations forming is pasture loading level and the principal factors of biotopes forming are soil moistening and its variability, ombroregime (humidification level), termoregime and regime of continentality (temperature-varying amplitude).

scholarly journals Partitioning the colonization and extinction components of beta diversity: Spatiotemporal species turnover across disturbance gradients

2020 ◽  
Author(s):  
Shinichi Tatsumi ◽  
Joachim Strengbom ◽  
Mihails Čugunovs ◽  
Jari Kouki
Keyword(s):  
Plant Communities ◽  
Beta Diversity ◽  
Species Turnover ◽  
Single Point ◽  
Relative Importance ◽  
Dynamic Nature ◽  
Colonization Dynamics ◽  
Per Se ◽  
The Given ◽  
Temporal Species Turnover

ABSTRACTChanges in species diversity often result from species losses and gains. The dynamic nature of beta diversity (i.e., spatial variation in species composition) that derives from such temporal species turnover, however, has been largely overlooked. Here, we disentangled extinction and colonization components of beta diversity by using the sets of species that went locally extinct and that newly colonized the given sites. We applied this concept of extinction and colonization beta diversity to plant communities that have been repeatedly measured in experimentally disturbed forests. We first found no difference in beta diversity across disturbance gradients when it was analyzed for communities at a single point in time. From this result, we might conclude that disturbance caused no impact on how species assemble across space. However, when we analyzed the extinction and colonization beta diversity, both measures were found to be significantly lower in disturbed sites compared to undisturbed sites. These results indicate that disturbance removed similar subsets of species across space, making communities differentiate, but at the same time induced spatially uniform colonization of new species, causing communities to homogenize. Consequently, the effects of these two processes canceled each other out. The relative importance of extinction and colonization components per se also changed temporally after disturbance. Analyses using extinction and colonization beta diversity allowed us to detect nonrandom dis- and re-assembly dynamics in plant communities. Our results suggest that common practices of analyzing beta diversity at one point in time can mask significant variation driven by disturbance. Acknowledging the extinction–colonization dynamics behind beta diversity is essential for understanding the spatiotemporal organization of biodiversity.

Competition between native and non-native plants.

2020 ◽  
pp. 291-307
Author(s):  
Elizabeth M. Wandrag ◽  
◽  
Jane A. Catford ◽  
◽  
◽  
...  
Keyword(s):  
Plant Species ◽  
Plant Communities ◽  
Native Species ◽  
Abiotic Factors ◽  
Invasion Biology ◽  
Competitive Interactions ◽  
Native Plant ◽  
Native Plant Species ◽  
New Locations ◽  
Strength Of Competition

The introduction of species to new locations leads to novel competitive interactions between resident native and newly-arriving non-native species. The nature of these competitive interactions can influence the suitability of the environment for the survival, reproduction and spread of non-native plant species, and the impact those species have on native plant communities. Indeed, the large literature on competition among plants reflects its importance in shaping the composition of plant communities, including the invasion success of non-native species. While competition and invasion theory have historically developed in parallel, the increasing recognition of the synergism between the two themes has led to new insights into how non-native plant species invade native plant communities, and the impacts they have on those plant communities. This chapter provides an entry point into the aspects of competition theory that can help explain the success, dominance and impacts of invasive species. It focuses on resource competition, which arises wherever the resources necessary for establishment, survival, reproduction and spread are in limited supply. It highlights key hypotheses developed in invasion biology that relate to ideas of competition, outlines biotic and abiotic factors that influence the strength of competition and species' relative competitive abilities, and describes when and how competition between non-native and native plant species can influence invasion outcomes. Understanding the processes that influence the strength of competition between non-native and native plant species is a necessary step towards understanding the causes and consequences of biological invasions.

Climate-driven abrupt changes in plant communities of desert and semi-desert region

2021 ◽  
Author(s):  
Reza Bagheri ◽  
Abolfazl Ranjbar Fordoei ◽  
Hojat Mousavi ◽  
Pejman Tahmasebi
Keyword(s):  
Plant Communities ◽  
Desert Region ◽  
Abrupt Changes

Multiple stabilizing pathways in wetland plant communities subjected to an elevation gradient

2019 ◽  
Vol 104 ◽  
pp. 704-710 ◽  
Author(s):  
Hui Fu ◽  
Guixiang Yuan ◽  
Erik Jeppesen ◽  
Dabing Ge ◽  
Dongsheng Zou ◽  
...  
Keyword(s):  
Plant Communities ◽  
Elevation Gradient ◽  
Wetland Plant ◽  
Wetland Plant Communities

scholarly journals Patterns of shrub abundance and relationships with other plant types within the forest–tundra ecotone in northern Canada

2018 ◽  
Vol 4 (4) ◽  
pp. 691-709 ◽  
Author(s):  
Karen A. Harper ◽  
Amanda A. Lavallee ◽  
Pavel Dodonov
Keyword(s):  
Wavelet Analysis ◽  
Spatial Pattern ◽  
Soil Ph ◽  
Environmental Variables ◽  
Generalized Least Squares ◽  
Tree Cover ◽  
Cascading Effects ◽  
Forest Tundra ◽  
Plant Groups ◽  
Tall Shrub

Throughout the forest–tundra ecotone where trees and tall shrubs are becoming more abundant, knowledge of associations between shrubs and surrounding vegetation could inform predictions of their changing relationships. We assessed shrubs in 1 m × 1 m contiguous quadrats along two ∼450 m transects across tundra and ecotone landscapes near Churchill, Canada to determine patterns in relation to lakeshore edges, soil pH, microtopography, and other plant groups. We used wavelet analysis to assess patterns and generalized least squares for relationships with environmental variables. Shrubs were taller and more diverse at edges, particularly in tundra. The ecotone was more complex than tundra with greater variation in tall shrub and tree cover, shrub height, and microtopography. Shrub richness was positively correlated with microtopography but exhibited no relationship with pH. Bivariate relationships of shrubs with other plant groups varied for different scales. In tundra, shrub richness was negatively correlated with graminoids, forbs, and moss, but positively correlated with lichens within 1 m; opposite relationships were found at 4–60 m scales. Relationships in the ecotone were reversed and more complex at different scales. As trees encroach in the tundra, the spatial pattern of shrubs will become more complex at a variety of scales, likely with cascading effects on other plant types.

The Holocene evolution of permafrost near the tree line, on the eastern coast of Hudson Bay (northern Quebec)

1987 ◽  
Vol 24 (11) ◽  
pp. 2206-2222 ◽  
Author(s):  
Michel Allard ◽  
Maurice K. Seguin
Keyword(s):  
Climatic Conditions ◽  
Snow Accumulation ◽  
Eastern Coast ◽  
Permafrost Degradation ◽  
Tree Line ◽  
Stratigraphic Sequence ◽  
Forest Tundra ◽  
Discontinuous Permafrost ◽  
Shrub Tundra ◽  
Peat Plateaus

Permafrost evolution in postglacial marine silts near the tree line was reconstructed using landform analysis, 14C dating, and palynostratigraphic analysis of peat sections. In the forest–tundra, below the tree line, four sites in peat plateaus have a stratigraphic sequence indicating an alluvial plain environment from 6000 to 4800 BP followed by a wetland supporting trees and shrubs with deep snow accumulation and without permafrost. Ground heave occurred between 1900 and 1200 BP as peat plateaus and palsas were formed. In the shrub–tundra, above the tree line, three permafrost sites with buried peat beds suggest that climatic conditions were cold enough for discontinuous permafrost in the surrounding landscape starting from land emergence, about 5800 BP; however, fen expansion and sedge peat accumulation continued over unfrozen ground until 2300, 1560, and 1400 BP. At these dates, the sites were buried with silt, probably as a result of mass wasting on nearby permafrost mounds and then permafrost aggraded under the sites. Generally, the palynostratigraphic data reflect a marked cooling of climate starting by 3200–2700 BP and culminating in a major period of permafrost aggradation between 1900 and 1200 BP. Permafrost degradation has been dominant since then despite other possible cold intervals. Nowadays, the permafrost in marine silts is twice as thick and three times more widespread in the shrub–tundra than in the forest–tundra.

Interactive effects of tree and herb cover on survivorship, physiology, and microclimate of conifer seedlings at the alpine tree-line ecotone

2005 ◽  
Vol 35 (3) ◽  
pp. 567-574 ◽  
Author(s):  
Eliza L Maher ◽  
Matthew J Germino ◽  
Niles J Hasselquist
Keyword(s):  
Forest Succession ◽  
Interactive Effects ◽  
Tree Cover ◽  
First Year ◽  
Abies Lasiocarpa ◽  
Tree Line ◽  
Conifer Seedlings ◽  
Factors Affecting ◽  
Nighttime Temperatures ◽  
Snowy Range

Factors affecting the establishment of trees in subalpine meadows are important to population dynamics of trees in the alpine tree-line ecotone (ATE). Interactive effects of tree and herb cover on conifer seedlings were investigated in the ATE of the Snowy Range, Wyoming, USA. Microclimate, physiology, and survivorship of first-year conifer seedlings of Pinus albicaulis Engelm., Picea engelmannii Parry, and Abies lasiocarpa Hook. were measured in response to manipulations of surrounding herb and tree cover, as well as water availability. Tree and herb cover had nearly additive effects on survivorship and photosynthesis of conifer seedlings, except under alleviated water stress. In P. albicaulis, photosynthesis was greater near compared with away from trees and herbs, and photosynthetic efficiency (Fv/Fm) increased under herb cover. Tree cover led to greater nighttime temperatures, soil water contents, and, like herb cover, shade from solar radiation for seedlings. We did not detect any negative responses of conifer seedlings to surrounding vegetation. Furthermore, the effect of surrounding vegetation on conifer establishment appeared dependent on the type of surrounding vegetation, the species of conifer, and microsite stress level. These factors may lead to variation in the way conifer seedlings interact with surrounding vegetation and could explain changes in the relative abundances of tree species during forest succession in ATEs.

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