scholarly journals Widespread Amazon forest tree mortality from a single cross-basin squall line event

2010 ◽  
Vol 37 (16) ◽  
pp. n/a-n/a ◽  
Author(s):  
Robinson I. Negrón-Juárez ◽  
Jeffrey Q. Chambers ◽  
Giuliano Guimaraes ◽  
Hongcheng Zeng ◽  
Carlos F. M. Raupp ◽  
...  
Keyword(s):  
Tree Mortality ◽  
Forest Tree ◽  
Squall Line ◽  
Amazon Forest ◽  
Single Cross

Vulnerability of Amazonian tree communities to global change

2020 ◽  
Author(s):  
Adriane Esquivel‐Muelbert ◽  
Thomas Pugh ◽  
Timothy Baker ◽  
Kyle Dexter ◽  
Simon Lewis ◽  
...  
Keyword(s):  
Tree Mortality ◽  
Slow Growth ◽  
Forest Monitoring ◽  
Amazon Forest ◽  
Principal Mechanism ◽  
Dead Trees ◽  
Tree Communities ◽  
Shade Tolerant Species ◽  
Vegetation Models ◽  
Global Vegetation

<p>Tree mortality is the principal mechanism whereby forests lose living biomass. This process has been observed to have increased across the Amazon forest over recent decades. Greater tree mortality rates have been attributed largely to an increase in the frequency and intensity of droughts, and to the intensification of competition, as a consequence of greater tree growth stimulated by higher CO<sub>2</sub>concentrations. Analysing the trends in mortality for different taxa allows us to test the contribution of these different drivers to the rise in tree mortality. Droughts are expected to kill wet-affiliated, large, and low wood density taxa. Increased competition is likely to affect slow growth, understory taxa. We assess data from over 30 years of forest monitoring across the Amazon to investigate the changes in mortality across different taxa, providing a greater understanding of the drivers of increased tree mortality across the basin and the vulnerability of these forests to water stress. We observed that the proportion of dead trees across different taxa has changed across the Amazon forest. We show an increase in the mortality of drought-vulnerable trees, particularly in those areas where dry climatic events have intensified over the last 30 years. However, the proportion of large taxa within the dead trees has not changed over the length of this study. We also observed indications of increasing competition-driven mortality represented by a decrease in abundance of slow-growth shade-tolerant species. A suite of mechanisms, varying regionally in importance, are acting synchronically to drive recent increases in tree death across Amazonia. The patterns and mechanisms observed here are amenable to incorporation within the latest generation of global vegetation models and Earth system models, providing a basis for improved simulations of forest dynamics in one of the world’s most carbon-dense ecosystems.</p>

Forest vulnerability and tree mortality in the Mediterranean: Impacts and Opportunities

2020 ◽  
Author(s):  
Tamir Klein
Keyword(s):  
Tree Mortality ◽  
Niche Partitioning ◽  
Common Garden ◽  
Fruit Trees ◽  
Forest Tree ◽  
Aleppo Pine ◽  
Mediterranean Forests ◽  
Mortality Pattern ◽  
Key Species ◽  
The Mediterranean

<p>The Mediterranean basin is a mosaic of human and natural landscapes, many of which are important forests and woodlands. Among global biomes, it has been under the longest anthropogenic stress, and today, in addition to the ongoing warming, it experiences drying. In my talk I will give examples from new research on the impacts of these processes on Mediterranean forests, as well as opportunities for increasing their sustainability under intensifying change.</p><p>Aleppo pine is perhaps the single most important forest tree species for the region, and has been grown for decades in common garden plots of provenances from around the region. Forest scientists from Spain, Italy, Greece and Israel, teamed up to synthesize the results of these provenance trials. Together, we produced the temperature and precipitation growth sensitivity profiles for Aleppo pine. Next, these profiles were applied on future climate maps, to show the potential expansion of this key species northward, as well as its extinction in many southern locations. In a seven decades-long tree mortality study across Israel, this mortality pattern is already occurring, driven by hotter and longer drought periods.</p><p>My current research is focused on finding new avenues to ensure the long-term existence of forests and trees in the Mediterranean. Examples include: (1) Mixed forests, with native broadleaf and conifer species coexisting, have high resilience, thanks to interspecific niche partitioning; (2) Native fruit trees have higher drought resistance than their cultivated relatives, and should be protected and integrated into local agriculture; (3) Native savannah trees from the southern fringes of the region are becoming more important, and offer new resilience strategies; and (4) Variations among Aleppo pine ecotypes give hope for the future suitability of this species across the Mediterranean.</p>

Gypsy Moth on a New Frontier: Forest Tree Defoliation and Mortality

1987 ◽  
Vol 4 (3) ◽  
pp. 128-133 ◽  
Author(s):  
Owen W. Herrick ◽  
David A. Gansner
Keyword(s):  
Gypsy Moth ◽  
Tree Mortality ◽  
Forest Tree ◽  
Tree Defoliation ◽  
Central Pennsylvania ◽  
New Frontier ◽  
Value Loss ◽  
Regional Estimates ◽  
Average Loss ◽  
Potential Impact

Abstract The gypsy moth infestation in central Pennsylvania has been closely monitored between 1979 and 1984 for tree defoliation and subsequent mortality. These losses serve as an indicator of potential impact as gypsy moth invades new territory. Tree mortality on study plots averaged 18%, worth $18.80 per acre. During the three most severe defoliation years (1980-82), plots that averaged less than 10% defoliation lost 13% of their trees by 1984. Where defoliation averaged 40% or more, the average tree loss was 28%. Timber losses predicted with models developed from the 1970s infestation in northeastern Pennsylvania were within 2% of the actual average loss. The models seem to be acceptable for obtaining broad regional estimates of potential tree mortality and value loss. North. J. Appl. For. 4:128-133, Sept. 1987.

scholarly journals Large-scale variations in the dynamics of Amazon forest canopy gaps from airborne lidar data and opportunities for tree mortality estimates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ricardo Dalagnol ◽  
Fabien H. Wagner ◽  
Lênio S. Galvão ◽  
Annia S. Streher ◽  
Oliver L. Phillips ◽  
...  
Keyword(s):  
Large Scale ◽  
Forest Canopy ◽  
Tree Mortality ◽  
Structural Changes ◽  
Regional Scale ◽  
Airborne Lidar ◽  
Amazon Forest ◽  
Gap Dynamics ◽  
Relative Height ◽  
Mortality Estimates

AbstractWe report large-scale estimates of Amazonian gap dynamics using a novel approach with large datasets of airborne light detection and ranging (lidar), including five multi-temporal and 610 single-date lidar datasets. Specifically, we (1) compared the fixed height and relative height methods for gap delineation and established a relationship between static and dynamic gaps (newly created gaps); (2) explored potential environmental/climate drivers explaining gap occurrence using generalized linear models; and (3) cross-related our findings to mortality estimates from 181 field plots. Our findings suggest that static gaps are significantly correlated to dynamic gaps and can inform about structural changes in the forest canopy. Moreover, the relative height outperformed the fixed height method for gap delineation. Well-defined and consistent spatial patterns of dynamic gaps were found over the Amazon, while also revealing the dynamics of areas never sampled in the field. The predominant pattern indicates 20–35% higher gap dynamics at the west and southeast than at the central-east and north. These estimates were notably consistent with field mortality patterns, but they showed 60% lower magnitude likely due to the predominant detection of the broken/uprooted mode of death. While topographic predictors did not explain gap occurrence, the water deficit, soil fertility, forest flooding and degradation were key drivers of gap variability at the regional scale. These findings highlight the importance of lidar in providing opportunities for large-scale gap dynamics and tree mortality monitoring over the Amazon.

scholarly journals Drought effects on litterfall, wood production and belowground carbon cycling in an Amazon forest: results of a throughfall reduction experiment

2008 ◽  
Vol 363 (1498) ◽  
pp. 1839-1848 ◽  
Author(s):  
Paulo M Brando ◽  
Daniel C Nepstad ◽  
Eric A Davidson ◽  
Susan E Trumbore ◽  
David Ray ◽  
...  
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Tree Mortality ◽  
Net Primary Productivity ◽  
Control Plot ◽  
Severe Drought ◽  
Amazon Forest ◽  
Belowground Production ◽  
Wood Production ◽  
Exclusion Experiment

The Amazon Basin experiences severe droughts that may become more common in the future. Little is known of the effects of such droughts on Amazon forest productivity and carbon allocation. We tested the prediction that severe drought decreases litterfall and wood production but potentially has multiple cancelling effects on belowground production within a 7-year partial throughfall exclusion experiment. We simulated an approximately 35–41% reduction in effective rainfall from 2000 through 2004 in a 1 ha plot and compared forest response with a similar control plot. Wood production was the most sensitive component of above-ground net primary productivity (ANPP) to drought, declining by 13% the first year and up to 62% thereafter. Litterfall declined only in the third year of drought, with a maximum difference of 23% below the control plot. Soil CO 2 efflux and its 14 C signature showed no significant treatment response, suggesting similar amounts and sources of belowground production. ANPP was similar between plots in 2000 and declined to a low of 41% below the control plot during the subsequent treatment years, rebounding to only a 10% difference during the first post-treatment year. Live aboveground carbon declined by 32.5 Mg ha −1 through the effects of drought on ANPP and tree mortality. Results of this unreplicated, long-term, large-scale ecosystem manipulation experiment demonstrate that multi-year severe drought can substantially reduce Amazon forest carbon stocks.

scholarly journals Competition and Climate Affects US Hardwood-Forest Tree Mortality

2013 ◽  
Vol 59 (4) ◽  
pp. 416-430 ◽  
Author(s):  
Daniel A. Yaussy ◽  
Louis R. Iverson ◽  
Stephen N. Matthews
Keyword(s):  
Tree Mortality ◽  
Forest Tree ◽  
Hardwood Forest

Understorey fire propagation and tree mortality on adjacent areas to an Amazonian deforestation fire

2010 ◽  
Vol 19 (6) ◽  
pp. 795 ◽  
Author(s):  
J. A. Carvalho Jr ◽  
C. A. Gurgel Veras ◽  
E. C. Alvarado ◽  
D. V. Sandberg ◽  
S. J. Leite ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Tree Mortality ◽  
Flame Height ◽  
Primary Forest ◽  
Amazon Forest ◽  
Mato Grosso ◽  
Land Clearing ◽  
Clear Cut ◽  
Fire Characteristics ◽  
Slash Burning

Fire characteristics in tropical ecosystems are poorly documented quantitatively in the literature. This paper describes an understorey fire propagating across the edges of a biomass burn of a cleared primary forest. The experiment was carried out in 2001 in the Amazon forest near Alta Floresta, state of Mato Grosso, Brazil, as part of biomass burning experiments conducted in the same area since 1997. The vegetation of a 200 × 200-m2 forested area was clear-cut in early June and burned in late August. The understorey fire that escaped from the main burn was monitored across the four sides of the land clearing area. Flame-front spread varied between 0.14 and 0.35 m min–1. Maximum flame height was about 30 cm and typical flame depth was 10 to 15 cm. Tree mortality was investigated in 2003 in four areas adjacent to the biomass burning experiment. A total of 210 trees were counted in the four areas, 29.5% were dead as a consequence of the understorey fire that had occurred 2 years before. This fire-caused mortality is evidence of the synergistic effect between slash burning, tree mortality and future fire vulnerability on the forest–land clearing interfaces.

scholarly journals Occurrence but not intensity of mortality rises towards the climatic trailing edge of tree species ranges in European forests

2020 ◽  
Author(s):  
Alexandre Changenet ◽  
Paloma Ruiz-Benito ◽  
Sophia Ratcliffe ◽  
Thibaut Fréjaville ◽  
Juliette Archambeau ◽  
...  
Keyword(s):  
Tree Species ◽  
Large Scale ◽  
Tree Mortality ◽  
Forest Tree ◽  
National Forest Inventory ◽  
Forest Composition ◽  
Trailing Edge ◽  
Species Ranges ◽  
Geographical Patterns ◽  
Background Mortality

AbstractAimTree mortality is increasing worldwide, leading to changes in forest composition and altering global biodiversity. Yet, due to the multi-faceted stochastic nature of tree mortality, large-scale spatial patterns of mortality across species ranges and their underlying drivers remain difficult to understand. Our main goal is to describe the geographical patterns and drivers of the occurrence and intensity of tree mortality in Europe. We hypothesize that the occurrence of mortality represents background mortality and is higher in the margin than the core populations, whereas the intensity of mortality could have a more even distribution according to the spatial and temporal stochasticity of die-off events.LocationEurope (Spain, France, Germany, Belgium, Sweden and Finland)Time period1981 to 2014.Major taxa studiedMore than 1.5 million trees belonging to 20 major forest tree speciesMethodsWe develop hurdle models to tease apart the occurrence and intensity of tree mortality in National Forest Inventory plots at range-wide scale. The occurrence of mortality indicates that at least one tree has died in the plot and the intensity of mortality refers to the number of trees dead per plot.ResultsThe highest mortality occurrence was found in peripheral regions and the climatic trailing edge linked with drought, whereas the intensity of mortality was driven by competition, drought and high temperatures and was uniformly scattered across species ranges.Main conclusionsOur findings provide a new perspective in our understanding of tree mortality across species ranges. We show that tree background mortality but not die-off is generally higher in the trailing edge populations, but whether other demographic traits such as growth, reproduction and regeneration would also decrease at the trailing edge of European tree populations needs to be explored.

scholarly journals Tropical forest tree mortality, recruitment and turnover rates: calculation, interpretation and comparison when census intervals vary

2004 ◽  
Vol 92 (6) ◽  
pp. 929-944 ◽  
Author(s):  
SIMON L. LEWIS ◽  
OLIVER L. PHILLIPS ◽  
DOUGLAS SHEIL ◽  
BARBARA VINCETI ◽  
TIMOTHY R. BAKER ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Tree Mortality ◽  
Forest Tree ◽  
Turnover Rates

scholarly journals Background mortality drivers of European tree species: climate change matters

2019 ◽  
Vol 286 (1900) ◽  
pp. 20190386 ◽  
Author(s):  
Adrien Taccoen ◽  
Christian Piedallu ◽  
Ingrid Seynave ◽  
Vincent Perez ◽  
Anne Gégout-Petit ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Species ◽  
Tree Mortality ◽  
Forest Tree ◽  
Climate Change Signal ◽  
Dead Trees ◽  
Background Mortality ◽  
Increasing Temperature ◽  
The Impact ◽  
Stand Characteristics

Increases in tree mortality rates have been highlighted in different biomes over the past decades. However, disentangling the effects of climate change on the temporal increase in tree mortality from those of management and forest dynamics remains a challenge. Using a modelling approach taking tree and stand characteristics into account, we sought to evaluate the impact of climate change on background mortality for the most common European tree species. We focused on background mortality, which is the mortality observed in a stand in the absence of abrupt disturbances, to avoid confusion with mortality events unrelated to long-term changes in temperature and rainfall. We studied 372 974 trees including 7312 dead trees from forest inventory data surveyed across France between 2009 and 2015. Factors related to competition, stand characteristics, management intensity, and site conditions were the expected preponderant drivers of mortality. Taking these main drivers into account, we detected a climate change signal on 45% of the 43 studied species, explaining an average 6% of the total modelled mortality. For 18 out of the 19 species sensitive to climate change, we evidenced greater mortality with increasing temperature or decreasing rainfall. By quantifying the mortality excess linked to the current climate change for European temperate forest tree species, we provide new insights into forest vulnerability that will prove useful for adapting forest management to future conditions.

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