Dataset Information

Widespread crown condition decline, food web disruption, and amplified tree mortality with increased climate change-type drought.

ABSTRACT: Climate change is progressively increasing severe drought events in the Northern Hemisphere, causing regional tree die-off events and contributing to the global reduction of the carbon sink efficiency of forests. There is a critical lack of integrated community-wide assessments of drought-induced responses in forests at the macroecological scale, including defoliation, mortality, and food web responses. Here we report a generalized increase in crown defoliation in southern European forests occurring during 1987-2007. Forest tree species have consistently and significantly altered their crown leaf structures, with increased percentages of defoliation in the drier parts of their distributions in response to increased water deficit. We assessed the demographic responses of trees associated with increased defoliation in southern European forests, specifically in the Iberian Peninsula region. We found that defoliation trends are paralleled by significant increases in tree mortality rates in drier areas that are related to tree density and temperature effects. Furthermore, we show that severe drought impacts are associated with sudden changes in insect and fungal defoliation dynamics, creating long-term disruptive effects of drought on food webs. Our results reveal a complex geographical mosaic of species-specific responses to climate change-driven drought pressures on the Iberian Peninsula, with an overwhelmingly predominant trend toward increased drought damage.

SUBMITTER: Carnicer J

PROVIDER: S-EPMC3029725 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Widespread crown condition decline, food web disruption, and amplified tree mortality with increased climate change-type drought.

Carnicer Jofre J Coll Marta M Ninyerola Miquel M Pons Xavier X Sánchez Gerardo G Peñuelas Josep J

Proceedings of the National Academy of Sciences of the United States of America 20110110 4

Climate change is progressively increasing severe drought events in the Northern Hemisphere, causing regional tree die-off events and contributing to the global reduction of the carbon sink efficiency of forests. There is a critical lack of integrated community-wide assessments of drought-induced responses in forests at the macroecological scale, including defoliation, mortality, and food web responses. Here we report a generalized increase in crown defoliation in southern European forests occur ...[more]

PMID: 21220333

Similar Datasets

Project description:Forest dieback because of drought is a global phenomenon threatening particular tree populations. Particularly vulnerable stands are usually located in climatically stressing locations such as xeric sites subjected to seasonal drought. These tree populations show a pronounced loss of vitality, growth decline, and high mortality in response to extreme climate events such as heat waves and droughts. However, dieback events do not uniformly affect stands, with some trees showing higher symptoms of drought vulnerability than other neighboring conspecifics. In this study, we investigated if trees showing different vulnerabilities to dieback showed lower growth rates (Grs) and higher sensitivities to the climate in the past using dendroecology and the Vaganov-Shashkin (VS) process-based growth model. We studied two Pinus pinaster stands with contrasting Grs showing recent dieback in the Iberian System, north-eastern Spain. We compared coexisting declining (D) and non-declining (ND) trees with crown defoliation values above and below the 50% threshold, respectively. The mean growth rate was lower in D than in ND trees in the two stands. The two vigor classes showed a growth divergence prior to the dieback onset and different responsiveness to climate. The ND trees were more responsive to changes in spring water balance and soil moisture than D trees, indicating a loss of growth responsiveness to the climate in stressed trees. Such an interaction between water availability and vigor was reflected by the VS-model simulations, which provided evidence for the observation that growth was mainly limited by low soil moisture in both sites. Such an interaction between water availability and vigor was reflected by the VS-model simulations, which provided evidence for the observation that growth was mainly limited by low soil moisture in both sites. The presented comparisons indicated different stand vulnerabilities to drought contingent on-site conditions. Further research should investigate the role played by environmental conditions and individual features such as access to soil water or hydraulic traits and implement them in process-based growth models to better forecast dieback.

Project description:An international data science challenge, called National Ecological Observatory Network-National Institute of Standards and Technology data science evaluation, was set up in autumn 2017 with the goal to improve the use of remote sensing data in ecological applications. The competition was divided into three tasks: (1) individual tree crown (ITC) delineation, for identifying the location and size of individual trees; (2) alignment between field surveyed trees and ITCs delineated on remote sensing data; and (3) tree species classification. In this paper, the methods and results of team Fondazione Edmund Mach (FEM) are presented. The ITC delineation (Task 1 of the challenge) was done using a region growing method applied to a near-infrared band of the hyperspectral images. The optimization of the parameters of the delineation algorithm was done in a supervised way on the basis of the Jaccard score using the training set provided by the organizers. The alignment (Task 2) between the delineated ITCs and the field surveyed trees was done using the Euclidean distance among the position, the height, and the crown radius of the ITCs and the field surveyed trees. The classification (Task 3) was performed using a support vector machine classifier applied to a selection of the hyperspectral bands and the canopy height model. The selection of the bands was done using the sequential forward floating selection method and the Jeffries Matusita distance. The results of the three tasks were very promising: team FEM ranked first in the data science competition in Task 1 and 2, and second in Task 3. The Jaccard score of the delineated crowns was 0.3402, and the results showed that the proposed approach delineated both small and large crowns. The alignment was correctly done for all the test samples. The classification results were good (overall accuracy of 88.1%, kappa accuracy of 75.7%, and mean class accuracy of 61.5%), although the accuracy was biased toward the most represented species.

Project description:Detecting the molecular basis of local adaptation and identifying selective drivers is still challenging in nonmodel species. The use of purely population genetic approaches is limited by some characteristics of genetic systems, such as pleiotropy and polygenic control, and parallel evidence from phenotypic-based experimental comparisons is required. In long-lived organisms, the detection of selective pressures might also be precluded by evolutionary lag times in response to the environment. Here, we used the English yew to showcase an example of a multiscale integrative approach in a nonmodel species with limited plant and genomic resources. We combined information from two independent sources, phenotypes in a common environment and genomic data in natural populations, to investigate the signature of selection. Growth differences among populations in a common environment, and phenological patterns of both shoot elongation and male strobili maturation, were associated with climate clines, providing evidence for local adaptation and guiding us in the selection of populations for genomic analyses. We used information on over 25,000 SNPs from c. 1,200 genes to infer the demographic history and to test for molecular signatures of selection at different levels: SNP, gene, and biological pathway. Our results confirmed an overall demographic history of population decline, but we also found evidence for putative local adaptation at the molecular level. We identified or confirmed several candidate genes for positive and negative selection in forest trees, including the pseudo-response regulator 7 (PRR7), an essential component of the circadian clock in plants. In addition, we successfully tested an approach to detect polygenic adaptation in biological pathways, allowing us to identify the flavonoid biosynthesis pathway as a candidate stress-response pathway that deserves further attention in other plants. Finally, our study contributes to the emerging view that explaining contemporary standing genetic variation requires considering adaptation to past climates, especially for long-lived trees.

Dataset Information

Widespread crown condition decline, food web disruption, and amplified tree mortality with increased climate change-type drought.

Publications

Widespread crown condition decline, food web disruption, and amplified tree mortality with increased climate change-type drought.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets