-
A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
-
Of particular concern are potential increases in tree mortality associated with climate- induced physiological stress and interactions with other climate-mediated processes such as insect outbreaks and wildfire. Despite this risk, existing projections of tree mortality are based on models that lack functionally realistic mortality mechanisms, and there has been no attempt to track observations of climate-driven tree mortality globally. Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world’s forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system. Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide.
heat, temperature, drought, tree mortality, forest dieoff
Located in
Resources
/
Climate Science Documents
-
Afforestation Effects on Soil Carbon Storage in the United States: A Synthesis
-
Afforestation (tree establishment on nonforested land) is a management option for increasing terrestrial C sequestration and mitigating rising atmo- spheric carbon dioxide because, compared to nonforested land uses, afforestation increases C storage in aboveground pools. However, because terrestrial ecosystems typically store most of their C in soils, afforestation impacts on soil organic carbon (SOC) storage are critical components of eco- system C budgets. We applied synthesis methods to identify the magnitude and drivers of afforestation impacts on SOC, and the temporal and verti- cal distributions of SOC change during afforestation in the United States. Meta-analysis of 39 papers from 1957 to 2010 indicated that previous land use drives afforestation impacts on SOC in mineral soils (overall average = +21%), but mined and other industrial lands (+173%) and wildlands (+31%) were the only groups that specifically showed categorically significant increases. Temporal patterns of SOC increase were statistically significant on former industrial and agricultural lands (assessed by continuous meta- analysis), and suggested that meaningful SOC increases require ≥15 and 30 yr of afforestation, respectively. Meta-analysis of 13C data demonstrated the greatest SOC changes occur at the surface soil of the profile, although par- tial replacement of C stocks derived from previous land uses was frequently detectable below 1 m. A geospatial analysis of 409 profiles from the National Soil Carbon Network database supported 13C meta-analysis results, indicating that transition from cultivation to forest increased A horizon SOC by 32%. In sum, our findings demonstrate that afforestation has significant, positive effects on SOC sequestration in the United States, although these effects require decades to manifest and primarily occur in the uppermost (and per- haps most vulnerable) portion of the mineral soil profile.
Abbreviations: BD, bulk density; CI, confidence interval; MAP, mean annual precipitation; MAT, mean annual temperature; SOC, soil organic carbon.
Located in
Resources
/
Climate Science Documents
-
Analysis of monotonic greening and browning trends from global NDVI time-series
-
Remotely sensed vegetation indices are widely used to detect greening and browning trends; especially the global coverage of time-series normalized difference vegetation index (NDVI) data which are available from 1981. Seasonality and serial auto-correlation in the data have previously been dealt with by integrating the data to annual values; as an alternative to reducing the temporal resolution, we apply harmonic analyses and non-parametric trend tests to the GIMMS NDVI dataset (1981–2006). Using the complete dataset, greening and browning trends were analyzed using a linear model corrected for seasonality by subtracting the seasonal component, and a seasonal non-parametric model. In a third approach, phenological shift and variation in length of growing season were accounted for by analyzing the time-series using vegetation development stages rather than calendar days. Results differed substantially between the models, even though the input data were the same. Prominent regional greening trends identified by several other studies were confirmed but the models were inconsistent in areas with weak trends. The linear model using data corrected for seasonality showed similar trend slopes to those described in previous work using linear models on yearly mean values. The non-parametric models demonstrated the significant influence of variations in phenology; accounting for these variations should yield more robust trend analyses and better understanding of vegetation trends.
Located in
Resources
/
Climate Science Documents
-
Climate Change's Growing Threat to Public Lands
-
Secretary Jewell attended the 2014 World Parks Congress in Australia, where she stressed the need for international cooperation on public lands and the growing threat of climate change.
Located in
Training
/
Videos and Webinars
-
Riparian Restoration Decision Support Tool
-
An innovative riparian planting and restoration decision support tool is now available to the conservation community. This user-friendly tool allows managers and decision-makers to rapidly identify and prioritize areas along the banks of rivers, streams, and lakes for restoration, making these ecosystems more resilient to disturbance and future changes in climate. It will also help the conservation community invest limited conservation dollars wisely, helping to deliver sustainable resources.
Located in
Tools & Resources
-
Riparian Restoration to Promote Climate Change Resilience in Eastern U.S. Streams
-
This presentation from Jason Coombs of the University of Massachusetts provides an update to the Steering Committee on this Appalachian LCC funded research project. The Riparian Restoration to Promote Climate Change Resilience in Eastern U.S. Streams is developing and implementing a user-friendly web-based tool to identify priority areas for riparian restoration in the context of predicted climate change at the appropriate scale needed by practitioners. A ‘shovel ready’ prioritization tool for managers facing immediate on-the-ground decisions will be developed. Then research will link directly to ongoing and future stream flow, temperature, and biological response modeling projects and decision support tools.
Located in
Cooperative
/
…
/
Past SC Meetings and Materials
/
Steering Committee Call 3/6/14
-
Climate Change Vulnerability Assessments Project Update
-
This presentation from Lesley Sneddon of NatureServe provides an update to the Steering Committee on a Appalachian LCC funded research project. Research is compiling climate change vulnerability assessments and other relevant information on vulnerable species and habitats, discerning the various methodologies and criteria used in these assessments, and using a team of expert peer reviewers to recommend the most efficient, effective, and appropriate methods for adoption by the Appalachian LCC for conservation and adaptation planning. The recommended method will then be deployed, resulting in vulnerability assessments for a suite of key species/habitats selected in consultation with partners of the Appalachian LCC.
Located in
Cooperative
/
…
/
Past SC Meetings and Materials
/
Steering Committee Call 3/6/14
-
Salamanders - The Hidden Jewels of Appalachia
-
If you want to hit paydirt the Appalachian region is the world’s salamander El Dorado—home to over 70 salamander species. The Appalachian region of the eastern United States is the world's epicenter for salamander biodiversity.
Located in
Training
/
Videos and Webinars
