Forest Sciences Commons^™

Understory Plant Communities Show Resistance To Drought, Hurricanes, And Experimental Warming In A Wet Tropical Forest, Aura M. Alonso-Rodríguez, Tana E. Wood, Jamarys Torres-Díaz, Molly A. Cavaleri, Sasha C. Reed, Benedicte Bachelot

Michigan Tech Publications

Global climate change has led to rising temperatures and to more frequent and intense climatic events, such as storms and droughts. Changes in climate and disturbance regimes can have non-additive effects on plant communities and result in complicated legacies we have yet to understand. This is especially true for tropical forests, which play a significant role in regulating global climate. We used understory vegetation data from the Tropical Responses to Altered Climate Experiment (TRACE) in Puerto Rico to evaluate how plant communities responded to climate warming and disturbance. The TRACE understory vegetation was exposed to a severe drought (2015), 2 …

Disturbance Reduces Fungal White-Rot Litter Mat Cover In A Wet Subtropical Forest, D. Jean Lodge, Ashley E. Van Beusekom, Grizelle González, Mareli Sánchez-Julia, Sarah Stankavich

USDA Forest Service / UNL Faculty Publications

Fungi that bind leaf litter into mats and produce white-rot via degradation of lignin and other aromatic compounds influence forest nutrient cycling and soil fertility. Extent of white-rot litter mats formed by basidiomycete fungi in Puerto Rico decreased in response to disturbances—a simulated hurricane treatment executed by canopy trimming and debris addition in 2014, a drought in 2015, a treefall, and two hurricanes 10 days apart in September 2017. Percent fungal litter mat cover ranged from 0.4% after Hurricanes Irma and Maria to a high of 53% in forest with undisturbed canopy prior to the 2017 hurricanes, with means mostly …

Poor Acclimation To Experimental Field Drought In Subalpine Forest Tree Seedlings, Alex Goke, Patrick H. Martin

Biological Sciences: Faculty Scholarship

The ability of tree species to acclimate and tolerate projected increases in drought frequency and intensity has fundamental implications for future forest dynamics with climate change. Inquiries to date on the drought tolerance capacities of tree species, however, have focused almost exclusively on mature trees with scant in situ work on seedlings, despite the central role that regeneration dynamics play in forest responses to changing conditions. We subjected naturally established seedlings of co-dominant subalpine conifer species (Abies lasiocarpa and Picea engelmannii) in the southern Rocky Mountains to 2 years of in situ summer precipitation exclusion, simulating summer drought …

Hydraulic Architecture Explains Species Moisture Dependency But Not Mortality Rates Across A Tropical Rainfall Gradient, Alexandria L. Pivovaroff, Brett T. Wolfe, Nate G. Mcdowell, Bradley O. Christoffersen, Stuart J. Davies, L. Turin Dickman, Charlotte Grossiord, Riley T. Leff, Alistair Rogers, Shawn P. Serbin

Biology Faculty Publications and Presentations

Intensified droughts are affecting tropical forests across the globe. However, the underlying mechanisms of tree drought response and mortality are poorly understood. Hydraulic traits and especially hydraulic safety margins (HSMs), that is, the extent to which plants buffer themselves from thresholds of water stress, provide insights into species-specific drought vulnerability. We investigated hydraulic traits during an intense drought triggered by the 2015–2016 El Niño on 27 canopy tree species across three tropical forest sites with differing precipitation. We capitalized on the drought event as a time when plant water status might approach or exceed thresholds of water stress. We investigated …

Splitting The Difference: Heterogeneous Soil Moisture Availability Affects Aboveground And Belowground Reserve And Mass Allocation In Trembling Aspen, Ashley T. Hart, Morgane Merlin, Erin Wiley, Simon M. Landhäusser

Aspen Bibliography

When exploring the impact of resource availability on perennial plants, artificial treatments often apply conditions homogeneously across space and time, even though this rarely reflects conditions in natural systems. To investigate the effects of spatially heterogeneous soil moisture on morphological and physiological responses, trembling aspen (Populus tremuloides) saplings were used in a split-pot experiment. Following the division of the root systems, saplings were established for a full year and then subjected to either heterogeneous (portion of the root system exposed to non-lethal drought) or homogeneous (whole root system exposed to non-lethal drought or well-watered) treatments. Above- and belowground …

Assessing And Mapping The Spatial-Temporal Change In Forest Phenology Of Arabuko-Sokoke Forest Using Moderate Resolution Satellite, Bailey Ytterdahl

Independent Study Project (ISP) Collection

This study focuses on coastal forests in Kenya that have some of the highest variety of flora and fauna, specifically Arabuko Sokoke Forest. Arabuko Sokoke Forest is located 110 miles north of Mombasa and 18 kilometers south of Malindi. This forest is known to be a worldwide biodiversity hotspot that is home to endemic and rare plants and animals. Within the Arabuko Sokoke Forest ecosystem, there are two main issues that challenge the conservation of the area. First, there has been more competition for land, primarily for agriculture and development. Second, there is an increase demand for forest resources due …

Effects Of Thinning On Dynamics And Drought Resistance Of Aspen-White Spruce Mixtures: Results From Two Study Sites In Saskatchewan, Philip G. Comeau

Aspen Bibliography

Drought stress associated with warm temperatures is causing increased mortality and reduced growth of trees in drier portions of the boreal forests of western Canada with both warming and drought expected to increase over the coming decades. While thinning is often shown to reduce drought stress, there is little information on its effects in stands comprised of mixtures of trembling aspen and white spruce that are common in the forests of this region. This study examined effects of pre-commercial thinning on aspen and spruce growth, response to drought stress, and stand dynamics for two study sites located in Saskatchewan, Canada. …

Drought- Conditioning Of Quaking Aspen (Populus Tremuloides Michx.) Seedlings During Nursery Production Modifies Seedling Anatomy And Physiology, Joshua L. Sloan, Owen T. Burney, Jeremiah R. Pinto

Aspen Bibliography

In the western US, quaking aspen (Populus tremuloides Michx.) regenerates primarily by root suckers after disturbances such as low to moderate severity fires. Planting aspen seedlings grown from seed may provide a mechanism to improve restoration success and genetic diversity on severely disturbed sites. However, few studies have examined the use of container-grown aspen seedlings for restoration purposes from both the outplanting and nursery production perspective. Thus, the purpose of this novel study was to examine how alterations in irrigation levels during nursery production across three seed sources would impact seedling performance attributes on harsh, dry outplanting sites. Irrigation …

Influence Of Forest-To-Silvopasture Conversion And Drought On Components Of Evapotranspiration, Adam P. Coble, Alexandra R. Contosta, Richard G. Smith, Nathan W. Siegert, Matthew A. Vadeboncoeur, Katie A. Jennings, Anthony J. Stewart, Heidi Asbjornsen

Natural Resources & the Environment

The northeastern U.S. is projected to experience more frequent short-term (1-2 month) droughts interspersed among larger precipitation events. Agroforestry practices such as silvopasture may mitigate these impacts of climate change while maintaining economic benefits of both agricultural and forestry practices. This study evaluated the effects of forest-to-silvopasture (i.e., 50% thinning) conversion on the components of evapotranspiration (transpiration, rainfall interception, and soil evaporation) during the growing season of 2016. The study coincided with a late-summer drought throughout the northeastern U.S., which allowed us to also evaluate the effects of forest-to-silvopasture conversion on drought responses of multiple tree species, including Pinus strobus, …

Drought In Temperate Mesic Regions Leads To Micro-Density Anomalies In White Pine, Elise Miller

CSB and SJU Distinguished Thesis

Wood density and wood volume determine the amount of carbon fixed by trees; however, while we are beginning to understand normal seasonal variation in wood density, anomalies are common, and their drivers are poorly understood. In conifers, wood density normally increases continuously throughout the season, but intra-annual fluctuations in wood density can occur and have been linked to climatic events. The causes of these fluctuations in density at the micro-scale (hereafter micro-density anomalies) are still debated.

Mesic regions are experiencing more droughts, but micro-density anomalies are rarely studied in these ecosystems. This study examined micro-density anomaly distribution within the boles …

Spatial Upscaling Of Forest Response To Drought, Wei Fang, Peipei Xu, Tao Zhao, Xiang Zhao, Hui Luo, George Hendrey, Chuixiang Yi

Publications and Research

We have integrated the observational capability of satellite remote sensing with plot-scale tree ring data to up-scale the evaluation of forest responses to drought. Satellite data, such as Normalized Difference Vegetation Index (NDVI), can provide a spatially continuous measure with limited temporal coverage, while tree Ring Width Index (RWI) provides accurate assessment with much longer time series local scales. Here, we explored the relationship between RWI and NDVI of three dominant species in the Southwestern United States (SWUS), and predicted RWI spatial distribution from 2001 to 2017 based on MODIS 1-km resolution NDVI data with stringent quality control. We detected …

Sudden Aspen Decline: A Review Of Pattern And Process In A Changing Climate, Jack A. Singer, Rob Turnbull, Mark Foster, Charles Bettigole, Brent R. Frey, Michelle C. Downey, Kristofer R. Covey, Mark S. Ashton

Aspen Bibliography

The American quaking aspen (Populus tremuloides Michx.) and its close relative, the Eurasian quaking aspen (Populus tremula L.), cover a realm that is perhaps the most expansive of all tree species in the world. In North America, sudden aspen decline (SAD) is a growing concern that marks the rapid decline of quaking aspen trees leading to mortality at the stand and landscape scale. Research suggests that drought and water stress are the primary causes of SAD. Predisposing factors (age, structure, and landscape position), as well as associated stressors (i.e., pests and pathogens), have been linked to mortality in affected stands. …

Tamm Review: Reforestation For Resilience In Dry Western U.S. Forests, Malcolm P. North, Jens T. Stevens, David F. Greene, Michelle Coppoletta, Eric E. Knapp, Andrew M. Latimer, Christina M. Restaino, Ryan E. Tompkins, Kevin R. Welch, Rob A. York, Derek J.N. Young, Jodi N. Axelson, Tom N. Buckley, Becky L. Estes, Rachel N. Hager, Jonathan W. Long, Marc D. Meyer, Steven M. Ostoja, Hugh D. Safford, Kristen L. Shive, Carmen L. Tubbesing, Dana Walsh, Chhaya M. Werner, Peter Wyrsch, Heather Vice

USDA Forest Service / UNL Faculty Publications

The increasing frequency and severity of fire and drought events have negatively impacted the capacity and success of reforestation efforts in many dry, western U.S. forests. Challenges to reforestation include the cost and safety concerns of replanting large areas of standing dead trees, and high seedling and sapling mortality rates due to water stress, competing vegetation, and repeat fires that burn young plantations. Standard reforestation practices have emphasized establishing dense conifer cover with gridded planting, sometimes called 'pines in lines', followed by shrub control and pre-commercial thinning. Resources for such intensive management are increasingly limited, reducing the capacity for young …

Will Seasonally Dry Tropical Forests Be Sensitive Or Resistant To Future Changes In Rainfall Regimes?, Kara Allen, Juan Manuel Dupuy, Maria G. Gei, Catherine Hulshof, David Medvigy, Camila Pizano, Christina M. Smith, Annette Trierweiler, Skip J. Van Bloem, Bonnie G. Waring, Xiangtao Xu, Jennifer S. Powers

Publications

Seasonally dry tropical forests (SDTF) are located in regions with alternating wet and dry seasons, with dry seasons that last several months or more. By the end of the 21st century, climate models predict substantial changes in rainfall regimes across these regions, but little is known about how individuals, species, and communities in SDTF will cope with the hotter, drier conditions predicted by climate models. In this review, we explore different rainfall scenarios that may result in ecological drought in SDTF through the lens of two alternative hypotheses: 1) these forests will be sensitive to drought because they are already …

Agricultural Trade Publications And The 2012 Midwestern U.S. Drought: A Missed Opportunity For Climate Risk Communication, Sarah P. Church, Tonya Haigh, Melissa Widhalm, Silvestre Garcia De Jalon, Nicholas Babin, Stuart Carlton, Michael Dunn, Katie Fagan, Cody L. Knutson, Linda Stalker Prokopy

Department of Forestry & Natural Resources Faculty Publications

The Midwestern United States experienced a devastating drought in 2012, leading to reduced corn and soybean yields and increased instances of pests and disease. Climate change induced weather variability and extremes are expected to increase in the future, and have and will continue to impact the agricultural sector. This study investigated how agricultural trade publications portrayed the 2012 U.S. Midwestern drought, whether climate change was associated with drought, and whether these publications laid out transformative adaptation measures farmers could undertake in order to increase their adaptive capacity for future climate uncertainty. We performed a content analysis of 1000 media reports …

A Forest Vulnerability Index Based On Drought And High Temperatures, David Mildrexler, Zhiqiang Yang, Warren B. Cohen, David M. Bell

USDA Forest Service / UNL Faculty Publications

Increasing forest stress and tree mortality has been directly linked to combinations of drought and high temperatures. The climatic changes expected during the next decades – large increases in mean temperature, increased heat waves, and significant long-term regional drying in the western USA – will likely increase chronic forest stress and mortality. The aim of this research is to develop and apply a new forest vulnerability index (FVI) associated with drought and high temperatures across the Pacific Northwest region (PNW; Oregon and Washington) of the USA during the MODIS Aqua era (since 2003). Our technique incorporates the alterations to canopy …

Contributing Factors For Drought In United States Forest Ecosystems Under Projected Future Climates And Their Uncertainty, Charles H. Luce, James M. Vose, Neil Pederson, John Campbell, Connie Millar, Patrick Kormos, Ross Woods

USDA Forest Service / UNL Faculty Publications

Observations of increasing global forest die-off related to drought are leading to more questions about potential increases in drought occurrence, severity, and ecological consequence in the future. Dry soils and warm temperatures interact to affect trees during drought; so understanding shifting risks requires some understanding of changes in both temperature and precipitation. Unfortunately, strong precipitation uncertainties in climate models yield substantial uncertainty in projections of drought occurrence. We argue that disambiguation of drought effects into temperature and precipitation-mediated processes can alleviate some of the implied uncertainty. In particular, the disambiguation can clarify geographic diversity in forest sensitivity to multifarious drivers …

The Linkages Between Photosynthesis, Productivity, Growth And Biomass In Lowland Amazonian Forests, Yadvinder Malhi, Christopher E. Doughty, Gregory R. Goldsmith, Daniel B. Metcalfe, Cécile A.J. Girardin, Toby R. Marthews, Jhon Del Aguila-Pasquel, Luiz E.O.C. Aragão, Alejandro Araujo-Murakami, Paulo Brando, Antonino C.L. Da Costa, Javier E. Silva-Espejo, Filio Farfán Amézquita, David R. Galbraith, Carlos A. Quesada, Wanderley Rocha, Norma Salinas-Revilla, Divino Silvério, Patrick Meir, Oliver L. Phillips

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Understanding the relationship between photosynthesis, net primary productivity and growth in forest ecosystems is key to understanding how these ecosystems will respond to global anthropogenic change, yet the linkages among these components are rarely explored in detail. We provide the first comprehensive description of the productivity, respiration and carbon allocation of contrasting lowland Amazonian forests spanning gradients in seasonal water deficit and soil fertility. Using the largest data set assembled to date, ten sites in three countries all studied with a standardized methodology, we find that (i) gross primary productivity (GPP) has a simple relationship with seasonal water deficit, but …

Effects Of Drought On Forests And Rangelands In The United States: A Comprehensive Science Synthesis, James M. Vose, James S. Clark, Charles H. Luce, Toral Patel-Weynand

USDA Forest Service / UNL Faculty Publications

This assessment provides input to the reauthorized National Integrated Drought Information System (NIDIS) and the National Climate Assessment (NCA), and it establishes the scientific foundation needed to manage for drought resilience and adaptation. Focal areas include drought characterization; drought impacts on forest processes and disturbances such as insect outbreaks and wildfire; and consequences on forest and rangeland values. Drought can be a severe natural disaster with substantial social and economic consequences. Drought becomes most obvious when large-scale changes are observed; however, even moderate drought can have long-lasting impacts on the structure and function of forests and rangelands without these obvious …

Tipping Point Of A Conifer-Based Ecosystem Under Severe Drought, Kaicheng Huang, Chuixiang Yi, Donghai Wu, Tao Zhou, Xiang Zhao, William J. Blanford, Suhua Wei, Hao Wu, Du Ling, Zheng Li

Publications and Research

Drought-induced tree mortality has recently received considerable attention. Questions have arisen over the necessary intensity and duration thresholds of droughts that are sufficient to trigger rapid forest declines. The values of such tipping points leading to forest declines due to drought are presently unknown. In this study, we have evaluated the potential relationship between the level of tree growth and concurrent drought conditions with data of the tree growth-related ring width index (RWI) of the two dominant conifer species (Pinus edulis and Pinus ponderosa) in the Southwestern United States (SWUS) and the meteorological drought-related standardized precipitation evapotranspiration index …

On Underestimation Of Global Vulnerability To Tree Mortality And Forest Die-Off From Hotter Drought In The Anthropocene, Craig D. Allen, David D. Breshears, Nate G. Mcdowell

United States Geological Survey: Staff Publications

Patterns, mechanisms, projections, and consequences of tree mortality and associated broadscale forest die-off due to drought accompanied by warmer temperatures—‘‘hotter drought’’, an emerging characteristic of the Anthropocene—are the focus of rapidly expanding literature. Despite recent observational, experimental, and modeling studies suggesting increased vulnerability of trees to hotter drought and associated pests and pathogens, substantial debate remains among research, management and policy-making communities regarding future tree mortality risks. We summarize key mortalityrelevant findings, differentiating between those implying lesser versus greater levels of vulnerability. Evidence suggesting lesser vulnerability includes forest benefits of elevated [CO2] and increased water-use efficiency; observed and modeled increases …

Negative Feedbacks On Bark Beetle Outbreaks: Widespread And Severe Spruce Beetle Infestation Restricts Subsequent Infestation, Sarah J. Hart, Thomas T. Veblen, Nathan Mietkiewicz, Dominik Kulakowski

Geography

Understanding disturbance interactions and their ecological consequences remains a major challenge for research on the response of forests to a changing climate. When, where, and how one disturbance may alter the severity, extent, or occurrence probability of a subsequent disturbance is encapsulated by the concept of linked disturbances. Here, we evaluated 1) how climate and forest habitat variables, including disturbance history, interact to drive 2000s spruce beetle (Dendroctonus rufipennis) infestation of Engelmann spruce (Picea engelmannii) across the Southern Rocky Mountains; and 2) how previous spruce beetle infestation affects subsequent infestation across the Flat Tops Wilderness in northwestern Colorado, which experienced …

Review Of The Potential Effects Of Climate Change On Quaking Aspen (Populus Tremuloides) In The Western United States And A New Tool For Surveying Aspen Decline, Toni L. Morelli, Susan C. Carr

Aspen Bibliography

We conducted a literature review of the effects of climate on the distribution and growth of quaking aspen (Populus tremuloides Michx.) in the Western United States. Based on our review, we summarize models of historical climate determi- nants of contemporary aspen distribution. Most quantitative climate-based models linked aspen presence and growth to moisture availability and solar radiation.

We describe research results pertaining to global climate change effects on aspen distribution and vigor. In addition, we present potential interactive effects related to climate change and natural disturbances and insect and pathogen outbreaks. Finally, we review the phenomenon of sudden aspen decline …

Slides: The Spotted Owl Controversy: An Example Of The Esa's Dominant Role In Federal Land Use Planning, Norman D. James

The Past, Present, and Future of Our Public Lands: Celebrating the 40th Anniversary of the Public Land Law Review Commission’s Report, One Third of the Nation’s Land (Martz Summer Conference, June 2-4)

Presenter: Norman D. James, Director, Fennemore Craig, PC (Phoenix, AZ)

17 slides

Slides: Celebrating Flpma: Land Use Planning At The Blm, Marcilynn Burke

The Past, Present, and Future of Our Public Lands: Celebrating the 40th Anniversary of the Public Land Law Review Commission’s Report, One Third of the Nation’s Land (Martz Summer Conference, June 2-4)

Presenter: Marcilynn Burke, BLM Deputy Director - Programs and Policy, U.S. Dept. of the Interior, (Washington, D.C.)

30 slides

Sp570 Drought-Tolerant Trees, The University Of Tennessee Agricultural Extension Service

Forestry, Trees, and Timber

Late-season droughts are common in southeastern landscapes. Many trees are stressed by prolonged periods of hot, dry weather. Selecting trees that use water efficiently without the need for frequent watering or irrigation is one way to make your landscape more resistant to droughts. With impending water shortages in many urban areas leading to prohibitions of irrigation or watering, planting trees that are more tolerant to drought conditions is the best long-term solution to a healthier, low-maintenance landscape.

Slides: Rethinking Western Water Law: Restoring The Public Interest In Western Water Law, Mark Squillace

Western Water Law, Policy and Management: Ripples, Currents, and New Channels for Inquiry (Martz Summer Conference, June 3-5)

Presenter: Mark Squillace, Director, Natural Resources Law Center, University of Colorado Law School

20 slides

Slides: Economic Incentives For Demand Reduction, Christopher Goemans

Western Water Law, Policy and Management: Ripples, Currents, and New Channels for Inquiry (Martz Summer Conference, June 3-5)

Presenter: Christopher Goemans, Department of Agriculture & Resource Economics, Colorado State University

17 slides

Slides: Delta Overview, Leo Winternitz

Western Water Law, Policy and Management: Ripples, Currents, and New Channels for Inquiry (Martz Summer Conference, June 3-5)

Presenter: Leo Winternitz, The Nature Conservancy, California Water Program, Sacramento, CA

17 slides

Agenda: Western Water Law, Policy And Management: Ripples, Currents, And New Channels For Inquiry, University Of Colorado Boulder. Natural Resources Law Center, Western Water Policy Program

Western Water Law, Policy and Management: Ripples, Currents, and New Channels for Inquiry (Martz Summer Conference, June 3-5)

In many pockets of the American West, stresses and demands on water resources are overwhelming our capacity to effectively manage change and accommodate the diversity of interests and values associated with our limited water resources.

This event will offer an opportunity for lawyers, policymakers, and water professionals to engage the experts on the challenges and emerging solutions to the most pressing water policy and management issues of the day.