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- Poorter, Lourens, et al.
(författare)
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Wet and dry tropical forests show opposite successional pathways in wood density but converge over time
- 2019
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Ingår i: Nature Ecology & Evolution. - : Nature Publishing Group. - 2397-334X. ; 3:6, s. 928-934
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Tidskriftsartikel (refereegranskat)abstract
- Tropical forests are converted at an alarming rate for agricultural use and pastureland, but also regrow naturally through secondary succession. For successful forest restoration, it is essential to understand the mechanisms of secondary succession. These mechanisms may vary across forest types, but analyses across broad spatial scales are lacking. Here, we analyse forest recovery using 1,403 plots that differ in age since agricultural abandonment from 50 sites across the Neotropics. We analyse changes in community composition using species-specific stem wood density (WD), which is a key trait for plant growth, survival and forest carbon storage. In wet forest, succession proceeds from low towards high community WD (acquisitive towards conservative trait values), in line with standard successional theory. However, in dry forest, succession proceeds from high towards low community WD (conservative towards acquisitive trait values), probably because high WD reflects drought tolerance in harsh early successional environments. Dry season intensity drives WD recovery by influencing the start and trajectory of succession, resulting in convergence of the community WD over time as vegetation cover builds up. These ecological insights can be used to improve species selection for reforestation. Reforestation species selected to establish a first protective canopy layer should, among other criteria, ideally have a similar WD to the early successional communities that dominate under the prevailing macroclimatic conditions.
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- Chazdon, Robin L., et al.
(författare)
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Carbon sequestration potential of second-growth forest regeneration in the Latin American tropics
- 2016
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 2:5
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Tidskriftsartikel (refereegranskat)abstract
- Regrowth of tropical secondary forests following complete or nearly complete removal of forest vegetation actively stores carbon in aboveground biomass, partially counterbalancing carbon emissions from deforestation, forest degradation, burning of fossil fuels, and other anthropogenic sources. We estimate the age and spatial extent of lowland second-growth forests in the Latin American tropics and model their potential aboveground carbon accumulation over four decades. Our model shows that, in 2008, second-growth forests (1 to 60 years old) covered 2.4 million km2 of land (28.1% of the total study area). Over 40 years, these lands can potentially accumulate a total aboveground carbon stock of 8.48 Pg C (petagrams of carbon) in aboveground biomass via low-cost natural regeneration or assisted regeneration, corresponding to a total CO2 sequestration of 31.09 Pg CO2. This total is equivalent to carbon emissions from fossil fuel use and industrial processes in all of Latin America and the Caribbean from 1993 to 2014. Ten countries account for 95% of this carbon storage potential, led by Brazil, Colombia, Mexico, and Venezuela. We model future land-use scenarios to guide national carbon mitigation policies. Permitting natural regeneration on 40% of lowland pastures potentially stores an additional 2.0 Pg C over 40 years. Our study provides information and maps to guide national-level forest-based carbon mitigation plans on the basis of estimated rates of natural regeneration and pasture abandonment. Coupled with avoided deforestation and sustainable forest management, natural regeneration of second-growth forests provides a low-cost mechanism that yields a high carbon sequestration potential with multiple benefits for biodiversity and ecosystem services.
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- Azorin-Molina, C., et al.
(författare)
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Trends of daily peak wind gusts in Spain and Portugal, 1961-2014
- 2016
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Ingår i: Journal of Geophysical Research-Atmospheres. - : American Geophysical Union (AGU). - 2169-897X. ; 121:3, s. 1059-1078
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Tidskriftsartikel (refereegranskat)abstract
- Given the inconsistencies of wind gust trends under the widespread decline in near-surface wind speed (stilling), our study aimed to assess trends of observed daily peak wind gusts (DPWG) across Spain and Portugal for 1961-2014 by analyzing trends of (i) the frequency (90th percentile) and (ii) the magnitude (wind speed maxima) of DPWG. Wind gust series were homogenized on a daily basis, using MM5-simulated series as reference, resulting in 80 suitable station-based data sets. The average DPWG 90th percentile frequency declined by -1.49ddecade(-1) (p<0.05) annually. This showed marked seasonal differences: decreasing in winter (-0.75ddecade(-1); p<0.05) and increasing in summer (+0.18ddecade(-1); p>0.10). A negligible trend was calculated for the annual magnitude of DPWG (-0.005ms(-1) decade(-1); p>0.10), with distinct seasonality: declining in winter (-0.168ms(-1) decade(-1); p<0.10) and increasing in summer (+0.130ms(-1) decade(-1); p<0.05). Combined, these results reveal less frequent and declining DPWG during the cold semester (November-April) and more frequent and increasing DPWG during the warm semester (May-October). Large-scale atmospheric changes such as the North Atlantic Oscillation Index (negative correlations similar to-0.4--0.6; p<0.05) and the Jenkinson and Collison scheme (positive correlations mainly with Westerly regime: similar to+0.5-0.6; p<0.05) partly account for the decadal fluctuations of both frequency and magnitude of DPWG, particularly in winter. However, the North Atlantic Oscillation index-DPWG relationships are smaller in spring, summer, and autumn (similar to-0.1--0.2; p>0.10), especially for the frequency, suggesting the role of local-to-mesoscale drivers.
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