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52 records – page 1 of 6.

4200 years of pine-dominated upland forest dynamics in west-central Mexico: human or natural legacy?

https://arctichealth.org/en/permalink/ahliterature155658
Source
Ecology. 2008 Jul;89(7):1893-907
Publication Type
Article
Date
Jul-2008
Author
Blanca L Figueroa-Rangel
Katherine J Willis
Miguel Olvera-Vargas
Author Affiliation
Oxford Long-term Ecology Laboratory, Oxford University Centre for the Environment, School of Geography, South Parks Road, Oxford, OX1 3QY, United Kingdom. bfrangel@cucsur.udg.mx
Source
Ecology. 2008 Jul;89(7):1893-907
Date
Jul-2008
Language
English
Publication Type
Article
Keywords
Climate
Ecosystem
Fossils
Human Activities
Humans
Mexico
Paleontology
Pinus - physiology
Pollen
Population Dynamics
Soil
Time Factors
Trees - physiology
Abstract
The pine-dominated forests of west-central Mexico are internationally recognized for their high biodiversity, and some areas are protected through various conservation measures including prohibition of human activity. In this region, however, there is evidence for human settlement dating back to ca. AD 1200. It is therefore unclear whether the present forest composition and structure are part of a successional stage following use by indigenous human populations during the past, or due to natural processes, such as climate. We present a study reconstructing the vegetation dynamics of pine-dominated forest over the past 4200 years using paleoecological techniques. Results from fossil pollen and charcoal indicate that, in this region, pine-dominated forests are the native vegetation type and not anthropogenically derived secondary succession. The predominant driving mechanism for the expansion of pine-dominated forest appears to be intervals of aridity and naturally induced burning. A close association is noted between pine abundance and longer-term climatic trends, including intervals of aridity between ca. 4200 and 2500, 1200 and 850, and 500 and 200 cal yr BP and shorter-term trends. Evident periodicity occurs in pine and Poaceae abundance every 80 years. These short-term quasi-periodic oscillations have been recorded in a number of lake and ocean sediments in Mexico and are thought to be linked to solar forcing resulting in drought cycles that occur at approximately the same time intervals.
PubMed ID
18705376 View in PubMed
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Aboveground and belowground legacies of native Sami land use on boreal forest in northern Sweden 100 years after abandonment.

https://arctichealth.org/en/permalink/ahliterature104173
Source
Ecology. 2014 Apr;95(4):963-77
Publication Type
Article
Date
Apr-2014
Author
Grégoire T Freschet
Lars Ostlund
Emilie Kichenin
David A Wardle
Source
Ecology. 2014 Apr;95(4):963-77
Date
Apr-2014
Language
English
Publication Type
Article
Keywords
Arctic Regions
Ecosystem
Environment
Environmental monitoring
Human Activities
Humans
Population Groups
Soil
Sweden
Time Factors
Trees - physiology
Abstract
Human activities that involve land-use change often cause major transformations to community and ecosystem properties both aboveground and belowground, and when land use is abandoned, these modifications can persist for extended periods. However, the mechanisms responsible for rapid recovery vs. long-term maintenance of ecosystem changes following abandonment remain poorly understood. Here, we examined the long-term ecological effects of two remote former settlements, regularly visited for -300 years by reindeer-herding Sami and abandoned -100 years ago, within an old-growth boreal forest that is considered one of the most pristine regions in northern Scandinavia. These human legacies were assessed through measurements of abiotic and biotic soil properties and vegetation characteristics at the settlement sites and at varying distances from them. Low-intensity land use by Sami is characterized by the transfer of organic matter towards the settlements by humans and reindeer herds, compaction of soil through trampling, disappearance of understory vegetation, and selective cutting of pine trees for fuel and construction. As a consequence, we found a shift towards early successional plant species and a threefold increase in soil microbial activity and nutrient availability close to the settlements relative to away from them. These changes in soil fertility and vegetation contributed to 83% greater total vegetation productivity, 35% greater plant biomass, and 23% and 16% greater concentrations of foliar N and P nearer the settlements, leading to a greater quantity and quality of litter inputs. Because decomposer activity was also 40% greater towards the settlements, soil organic matter cycling and nutrient availability were further increased, leading to likely positive feedbacks between the aboveground and belowground components resulting from historic land use. Although not all of the activities typical of Sami have left visible residual traces on the ecosystem after 100 years, their low-intensity but long-term land use at settlement sites has triggered a rejuvenation of the ecosystem that is still present. Our data demonstrates that aboveground-belowground interactions strongly control ecosystem responses to historical human land use and that medium- to long-term consequences of even low-intensity human activities must be better accounted for if we are to predict and manage ecosystems succession following land-use abandonment.
PubMed ID
24933815 View in PubMed
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[Altitude-belt zonality of wood vegetation within mountainous regions of the Sayan Mountains: a model of ecological second-order phase transitions ].

https://arctichealth.org/en/permalink/ahliterature259810
Source
Zh Obshch Biol. 2014 Jan-Feb;75(1):38-47
Publication Type
Article
Author
V G Sukhovol'skii
T M Ovchinnikova
S D Baboi
Source
Zh Obshch Biol. 2014 Jan-Feb;75(1):38-47
Language
Russian
Publication Type
Article
Keywords
Altitude
Biodiversity
Ecosystem
Forests
Models, Statistical
Plant Dispersal - physiology
Siberia
Trees - physiology
Abstract
As a description of altitude-belt zonality of wood vegetation, a model of ecological second-order transitions is proposed. Objects of the study have been chosen to be forest cenoses of the northern slope of Kulumyss Ridge (the Sayan Mauntains), while the results are comprised by the altitude profiles of wood vegetation. An ecological phase transition can be considered as the transition of cenoses at different altitudes from the state of presence of certain tree species within the studied territory to the state of their absence. By analogy with the physical model of second-order, phase transitions the order parameter is introduced (i.e., the area portion occupied by a single tree species at the certain altitude) as well as the control variable (i.e., the altitude of the wood vegetation belt). As the formal relation between them, an analog of the Landau's equation for phase transitions in physical systems is obtained. It is shown that the model is in a good accordance with the empirical data. Thus, the model can be used for estimation of upper and lower boundaries of altitude belts for individual tree species (like birch, aspen, Siberian fir, Siberian pine) as well as the breadth of their ecological niches with regard to altitude. The model includes also the parameters that describe numerically the interactions between different species of wood vegetation. The approach versatility allows to simplify description and modeling of wood vegetation altitude zonality, and enables assessment of vegetation cenoses response to climatic changes.
PubMed ID
25486796 View in PubMed
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Applying a framework for landscape planning under climate change for the conservation of biodiversity in the Finnish boreal forest.

https://arctichealth.org/en/permalink/ahliterature267267
Source
Glob Chang Biol. 2015 Feb;21(2):637-51
Publication Type
Article
Date
Feb-2015
Author
Adriano Mazziotta
Maria Triviño
Olli-Pekka Tikkanen
Jari Kouki
Harri Strandman
Mikko Mönkkönen
Source
Glob Chang Biol. 2015 Feb;21(2):637-51
Date
Feb-2015
Language
English
Publication Type
Article
Keywords
Biodiversity
Climate change
Conservation of Natural Resources - methods
Finland
Models, Biological
Taiga
Trees - physiology
Abstract
Conservation strategies are often established without consideration of the impact of climate change. However, this impact is expected to threaten species and ecosystem persistence and to have dramatic effects towards the end of the 21st century. Landscape suitability for species under climate change is determined by several interacting factors including dispersal and human land use. Designing effective conservation strategies at regional scales to improve landscape suitability requires measuring the vulnerabilities of specific regions to climate change and determining their conservation capacities. Although methods for defining vulnerability categories are available, methods for doing this in a systematic, cost-effective way have not been identified. Here, we use an ecosystem model to define the potential resilience of the Finnish forest landscape by relating its current conservation capacity to its vulnerability to climate change. In applying this framework, we take into account the responses to climate change of a broad range of red-listed species with different niche requirements. This framework allowed us to identify four categories in which representation in the landscape varies among three IPCC emission scenarios (B1, low; A1B, intermediate; A2, high emissions): (i) susceptible (B1 = 24.7%, A1B = 26.4%, A2 = 26.2%), the most intact forest landscapes vulnerable to climate change, requiring management for heterogeneity and resilience; (ii) resilient (B1 = 2.2%, A1B = 0.5%, A2 = 0.6%), intact areas with low vulnerability that represent potential climate refugia and require conservation capacity maintenance; (iii) resistant (B1 = 6.7%, A1B = 0.8%, A2 = 1.1%), landscapes with low current conservation capacity and low vulnerability that are suitable for restoration projects; (iv) sensitive (B1 = 66.4%, A1B = 72.3%, A2 = 72.0%), low conservation capacity landscapes that are vulnerable and for which alternative conservation measures are required depending on the intensity of climate change. Our results indicate that the Finnish landscape is likely to be dominated by a very high proportion of sensitive and susceptible forest patches, thereby increasing uncertainty for landscape managers in the choice of conservation strategies.
Notes
Erratum In: Glob Chang Biol. 2015 Sep;21(9):319326386356
PubMed ID
25044467 View in PubMed
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Changes in Arctic vegetation amplify high-latitude warming through the greenhouse effect.

https://arctichealth.org/en/permalink/ahliterature98346
Source
Proc Natl Acad Sci U S A. 2010 Jan 26;107(4):1295-300
Publication Type
Article
Date
Jan-26-2010
Author
Abigail L Swann
Inez Y Fung
Samuel Levis
Gordon B Bonan
Scott C Doney
Author Affiliation
Department of Earth & Planetary Science, University of California, Berkeley, CA 94720, USA. aswann@atmos.berkeley.edu
Source
Proc Natl Acad Sci U S A. 2010 Jan 26;107(4):1295-300
Date
Jan-26-2010
Language
English
Publication Type
Article
Keywords
Arctic Regions
Ecosystem
Global warming
Greenhouse Effect
Trees - physiology
Abstract
Arctic climate is projected to change dramatically in the next 100 years and increases in temperature will likely lead to changes in the distribution and makeup of the Arctic biosphere. A largely deciduous ecosystem has been suggested as a possible landscape for future Arctic vegetation and is seen in paleo-records of warm times in the past. Here we use a global climate model with an interactive terrestrial biosphere to investigate the effects of adding deciduous trees on bare ground at high northern latitudes. We find that the top-of-atmosphere radiative imbalance from enhanced transpiration (associated with the expanded forest cover) is up to 1.5 times larger than the forcing due to albedo change from the forest. Furthermore, the greenhouse warming by additional water vapor melts sea-ice and triggers a positive feedback through changes in ocean albedo and evaporation. Land surface albedo change is considered to be the dominant mechanism by which trees directly modify climate at high-latitudes, but our findings suggest an additional mechanism through transpiration of water vapor and feedbacks from the ocean and sea-ice.
PubMed ID
20080628 View in PubMed
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A climate-change risk analysis for world ecosystems.

https://arctichealth.org/en/permalink/ahliterature80994
Source
Proc Natl Acad Sci U S A. 2006 Aug 29;103(35):13116-20
Publication Type
Article
Date
Aug-29-2006
Author
Scholze Marko
Knorr Wolfgang
Arnell Nigel W
Prentice I Colin
Author Affiliation
Quantifying and Understanding the Earth System, Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, United Kingdom. marko.scholze@bristol.ac.uk
Source
Proc Natl Acad Sci U S A. 2006 Aug 29;103(35):13116-20
Date
Aug-29-2006
Language
English
Publication Type
Article
Keywords
Atmosphere - chemistry
Carbon - analysis
Ecosystem
Greenhouse Effect
Models, Theoretical
Risk assessment
Trees - physiology
Abstract
We quantify the risks of climate-induced changes in key ecosystem processes during the 21st century by forcing a dynamic global vegetation model with multiple scenarios from 16 climate models and mapping the proportions of model runs showing forest/nonforest shifts or exceedance of natural variability in wildfire frequency and freshwater supply. Our analysis does not assign probabilities to scenarios or weights to models. Instead, we consider distribution of outcomes within three sets of model runs grouped by the amount of global warming they simulate: 3 degrees C. High risk of forest loss is shown for Eurasia, eastern China, Canada, Central America, and Amazonia, with forest extensions into the Arctic and semiarid savannas; more frequent wildfire in Amazonia, the far north, and many semiarid regions; more runoff north of 50 degrees N and in tropical Africa and northwestern South America; and less runoff in West Africa, Central America, southern Europe, and the eastern U.S. Substantially larger areas are affected for global warming >3 degrees C than for 3 degrees C this sink converts to a carbon source during the 21st century (implying a positive climate feedback) in 44% of cases. The risks continue increasing over the following 200 years, even with atmospheric composition held constant.
PubMed ID
16924112 View in PubMed
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Climate feedbacks at the tundra-taiga interface.

https://arctichealth.org/en/permalink/ahliterature4339
Source
Ambio. 2002 Aug;Spec No 12:47-55
Publication Type
Article
Date
Aug-2002
Author
Richard Harding
Peter Kuhry
Torben R Christensen
Martin T Sykes
Rutger Dankers
Sandra van der Linden
Author Affiliation
Land/Atmosphere Interaction Section, Centre for Ecology and Hydrology at Wallingford, England. rjh@ceh.ac.uk
Source
Ambio. 2002 Aug;Spec No 12:47-55
Date
Aug-2002
Language
English
Publication Type
Article
Keywords
Air
Arctic Regions
Cold Climate
Environmental health
Feedback
Forecasting
Fresh Water
Greenhouse Effect
Health Priorities
Humans
Models, Theoretical
Predictive value of tests
Research
Research Support, Non-U.S. Gov't
Seasons
Sensitivity and specificity
Snow
Temperature
Thermodynamics
Trees - physiology
Weather
Abstract
Feedbacks, or internal interactions, play a crucial role in the climate system. Negative feedback will reduce the impact of an external perturbation, a positive feedback will amplify the effect and could lead to an unstable system. Many of the feedbacks found in the climate system are positive; thus, for example, increasing CO2 levels will increase temperature, reduce the snow cover, increase the absorption of radiation and hence increase temperature further. The most obvious feedbacks, such as the snow example quoted above, are already included within our models of the climate and earth system. Others, such as the impact of increasing forest cover due to global warming, are only just being included. Others, such as, the impact of global warming on the northern peatlands and the impact of freshwater flows on the Arctic Ocean are not yet considered. The contrast in surface characteristics between low tundra vegetation to high taiga forest is considerable. The contrast is greatest in the winter, when the tundra is snow covered but the trees of the taiga protrude through the snow pack, and is probably the greatest contrast found on the land surface anywhere. This variation causes massive changes in the energy fluxes at the surface and hence the temperature conditions on the ground and within the atmosphere. There will be large resultant changes in the vegetation development, the carbon fluxes, the permafrost and the hydrology. The Arctic is already experiencing change and it is essential for us to understand the basic processes, and how these interact, to be confident of our predictions of environmental change in the future.
PubMed ID
12374059 View in PubMed
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Climate sensitivity of reproduction in a mast-seeding boreal conifer across its distributional range from lowland to treeline forests.

https://arctichealth.org/en/permalink/ahliterature257147
Source
Oecologia. 2014 Mar;174(3):665-77
Publication Type
Article
Date
Mar-2014
Author
Carl A Roland
Joshua H Schmidt
Jill F Johnstone
Author Affiliation
National Park Service, Central Alaska Network, 4175 Geist Road, Fairbanks, AK, 99709, USA, carl_roland@nps.gov.
Source
Oecologia. 2014 Mar;174(3):665-77
Date
Mar-2014
Language
English
Publication Type
Article
Keywords
Alaska
Altitude
Bayes Theorem
Climate
Climate change
Droughts
Ecosystem
Picea - physiology
Reproduction
Seeds - physiology
Temperature
Trees - physiology
Abstract
Mast-seeding conifers such as Picea glauca exhibit synchronous production of large seed crops over wide areas, suggesting climate factors as possible triggers for episodic high seed production. Rapidly changing climatic conditions may thus alter the tempo and spatial pattern of masting of dominant species with potentially far-reaching ecological consequences. Understanding the future reproductive dynamics of ecosystems including boreal forests, which may be dominated by mast-seeding species, requires identifying the specific cues that drive variation in reproductive output across landscape gradients and among years. Here we used annual data collected at three sites spanning an elevation gradient in interior Alaska, USA between 1986 and 2011 to produce the first quantitative models for climate controls over both seedfall and seed viability in P. glauca, a dominant boreal conifer. We identified positive associations between seedfall and increased summer precipitation and decreased summer warmth in all years except for the year prior to seedfall. Seed viability showed a contrasting response, with positive correlations to summer warmth in all years analyzed except for one, and an especially positive response to warm and wet conditions in the seedfall year. Finally, we found substantial reductions in reproductive potential of P. glauca at high elevation due to significantly reduced seed viability there. Our results indicate that major variation in the reproductive potential of this species may occur in different landscape positions in response to warming, with decreasing reproductive success in areas prone to drought stress contrasted with increasing success in higher elevation areas currently limited by cool summer temperatures.
PubMed ID
24213628 View in PubMed
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Climate warming feedback from mountain birch forest expansion: reduced albedo dominates carbon uptake.

https://arctichealth.org/en/permalink/ahliterature259946
Source
Glob Chang Biol. 2014 Jul;20(7):2344-55
Publication Type
Article
Date
Jul-2014
Author
Heleen A de Wit
Anders Bryn
Annika Hofgaard
Jonas Karstensen
Maria M Kvalevåg
Glen P Peters
Source
Glob Chang Biol. 2014 Jul;20(7):2344-55
Date
Jul-2014
Language
English
Publication Type
Article
Keywords
Animal Husbandry
Betula - physiology
Biomass
Carbon - metabolism
Climate change
Environment
Forests
Models, Theoretical
Norway
Seasons
Snow
Temperature
Trees - physiology
Abstract
Expanding high-elevation and high-latitude forest has contrasting climate feedbacks through carbon sequestration (cooling) and reduced surface reflectance (warming), which are yet poorly quantified. Here, we present an empirically based projection of mountain birch forest expansion in south-central Norway under climate change and absence of land use. Climate effects of carbon sequestration and albedo change are compared using four emission metrics. Forest expansion was modeled for a projected 2.6 °C increase in summer temperature in 2100, with associated reduced snow cover. We find that the current (year 2000) forest line of the region is circa 100 m lower than its climatic potential due to land-use history. In the future scenarios, forest cover increased from 12% to 27% between 2000 and 2100, resulting in a 59% increase in biomass carbon storage and an albedo change from 0.46 to 0.30. Forest expansion in 2100 was behind its climatic potential, forest migration rates being the primary limiting factor. In 2100, the warming caused by lower albedo from expanding forest was 10 to 17 times stronger than the cooling effect from carbon sequestration for all emission metrics considered. Reduced snow cover further exacerbated the net warming feedback. The warming effect is considerably stronger than previously reported for boreal forest cover, because of the typically low biomass density in mountain forests and the large changes in albedo of snow-covered tundra areas. The positive climate feedback of high-latitude and high-elevation expanding forests with seasonal snow cover exceeds those of afforestation at lower elevation, and calls for further attention of both modelers and empiricists. The inclusion and upscaling of these climate feedbacks from mountain forests into global models is warranted to assess the potential global impacts.
PubMed ID
24343906 View in PubMed
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52 records – page 1 of 6.