Skip to main content

Adrian Das

I am an Ecologist with the U.S. Geological Survey's Western Ecological Research Center, stationed at Sequoia and Kings Canyon National Parks. I study tree dynamics with a particular focus on tree mortality processes. My work is aimed at improving our understanding of western forests and increasing our capacity to assess how they will be affected by a changing climate.

RESEARCH INTERESTS

  • Forest ecology
  • Forest dynamics
  • Tree mortality
  • Tree growth
  • Climatic change

Education and Certifications

  • PhD from University of California at Berkeley, Forest Ecology 2007
    BS from University of Michigan, Chemistry and Cellular Molecular Biology, 1995

Science and Products

link
Tree mortality during California’s extreme drought

Forest health and drought response

Forests provide society with economically important and often irreplaceable goods and services, such as wood products, carbon sequestration, clean water, biodiversity, and recreational opportunities. Yet hotter droughts (droughts in which unusually high temperatures exacerbate the effects of low precipitation) are projected to increase in frequency and intensity in coming decades, potentially...
By
Ecosystems, Climate Research and Development Program, Western Ecological Research Center (WERC)
link

Forest health and drought response

Forests provide society with economically important and often irreplaceable goods and services, such as wood products, carbon sequestration, clean water, biodiversity, and recreational opportunities. Yet hotter droughts (droughts in which unusually high temperatures exacerbate the effects of low precipitation) are projected to increase in frequency and intensity in coming decades, potentially...
Learn More
link
Meadow in the Sierra Nevada

Post-Fire Conifer Regeneration Under a Warming Climate: Will Severe Fire Be a Catalyst for Forest Loss?

The Southwest U.S. is experiencing hotter droughts, which are contributing to more frequent, severe wildfires. These droughts also stress vegetation, which can make it more difficult for forests to recover after fire. Forest regeneration in burned areas may be limited because seeds have to travel long distances to recolonize, and when they do arrive, conditions are often unfavorably hot and dry. C
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Post-Fire Conifer Regeneration Under a Warming Climate: Will Severe Fire Be a Catalyst for Forest Loss?

The Southwest U.S. is experiencing hotter droughts, which are contributing to more frequent, severe wildfires. These droughts also stress vegetation, which can make it more difficult for forests to recover after fire. Forest regeneration in burned areas may be limited because seeds have to travel long distances to recolonize, and when they do arrive, conditions are often unfavorably hot and dry. C
Learn More
link
Meadow in the Sierra Nevada

Post-Fire Conifer Regeneration Under a Warming Climate: Will Severe Fire Be a Catalyst for Forest Loss?

The Southwest U.S. is experiencing hotter droughts, which are contributing to more frequent, severe wildfires. These droughts also stress vegetation, which can make it more difficult for forests to recover after fire. Forest regeneration in burned areas may be limited because seeds have to travel long distances to recolonize, and when they do arrive, conditions are often unfavorably hot and dry. C
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Post-Fire Conifer Regeneration Under a Warming Climate: Will Severe Fire Be a Catalyst for Forest Loss?

The Southwest U.S. is experiencing hotter droughts, which are contributing to more frequent, severe wildfires. These droughts also stress vegetation, which can make it more difficult for forests to recover after fire. Forest regeneration in burned areas may be limited because seeds have to travel long distances to recolonize, and when they do arrive, conditions are often unfavorably hot and dry. C
Learn More
link
Photo depicting drought-related tree mortality in Sequoia National Park

Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts

Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate ch...
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts

Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate ch...
Learn More
link
Photo depicting drought-related tree mortality in Sequoia National Park

Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts

Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate ch...
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts

Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate ch...
Learn More
link
Flames consume woody fuels in a managed wildfire, New Mexico

Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest

Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this imm
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest

Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this imm
Learn More
link
Forest in flames. Smoke billowing

Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains?

In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks t...
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains?

In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks t...
Learn More
link
Flames consume woody fuels in a managed wildfire, New Mexico

Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest

Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this imm
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest

Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this imm
Learn More
link
Forest in flames. Smoke billowing

Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains?

In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks t...
By
Climate Adaptation Science Centers, Climate Adaptation Science Center
link

Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains?

In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks t...
Learn More
link
USGS science for a changing world logo

Characterizing a link in the terrestrial carbon cycle: a global overview of individual tree mass growth

Forests sequester the majority of the terrestrial biosphere’s carbon and are key components of the global carbon cycle, potentially contributing substantial feedbacks to ongoing climatic changes. It is therefore remarkable that no consensus yet exists about the fundamental nature of tree mass growth (and thus carbon sequestration rate). Specifically, does tree mass growth rate increase, decrease,
By
John Wesley Powell Center for Analysis and Synthesis
link

Characterizing a link in the terrestrial carbon cycle: a global overview of individual tree mass growth

Forests sequester the majority of the terrestrial biosphere’s carbon and are key components of the global carbon cycle, potentially contributing substantial feedbacks to ongoing climatic changes. It is therefore remarkable that no consensus yet exists about the fundamental nature of tree mass growth (and thus carbon sequestration rate). Specifically, does tree mass growth rate increase, decrease,
Learn More

Calibration and Validation Data and Model Coefficients for Mixed Conifer Vulnerability Project from Sequoia and Kings Canyon National Park 2015 to 2019

These datasets contain the attributes of individual trees located in and around Sequoia and Kings Canyon national parks. Attributes include remote sensing indices, terrain characteristics, and-- for the calibration data-- tree size and growth rates. Calibration data (mixedconifervulnerability_calibrationdataset.csv) were collected in long term research plots where trees are visited annually to che
By
Western Ecological Research Center (WERC)

Sequoia and Yosemite National Parks Mortality and Fire Data (1990-2019) for Competition-Fire-Drought Interaction Analysis

This dataset records mortality-- including involvement of bark beetles-- and burn severity information for trees in long term forest dynamics plots in Sequoia National Park and Yosemite National Park that experienced fire. These data support the following publication: Furniss, T.J., Das, A.J., van Mantgem, P.J., Stephenson, N.L. and Lutz, J.A., 2021. Crowding, climate, and the case for soci
By
Western Ecological Research Center (WERC)

Data for Use in poscrptR Post-fire Conifer Regeneration Prediction Model

These data support poscrptR (Wright et al. 2021). poscrptR is a shiny app that predicts the probability of post-fire conifer regeneration for fire data supplied by the user. The predictive model was fit using presence/absence data collected in 4.4m radius plots (60 square meters). Please refer to Stewart et al. (2020) for more details concerning field data collection, the model fitting process, an
By
Western Ecological Research Center (WERC)

Forest Structure Data for Burned and Unburned Sites at Sequoia and Kings Canyon National Parks

These data represent tree diameter, species, mortality status, and plot attributes from 164 plots in Sequoia and Kings Canyon national parks, California. Plots were matched with local records of recent fire history to determine burn status and year burned if applicable. These data support the following publication:
By
Western Ecological Research Center (WERC)

Post-fire conifer regeneration observations for National Forest land in California (2009 - 2017)

This data consists of presence/absence observations for post-fire conifer regeneration. The data also includes estimates of plot-level topography (slope, aspect), relativized differenced normalized burn ratio (RdNBR), post-fire climate, live basal area, and seed rain. These data support the following publication:
By
Western Ecological Research Center (WERC)

Seed and Associated Tree Data from Long Term Research Plots in Sequoia and Yosemite national parks

This dataset was used as part of a continent-wide analysis of tree fecundity and its association with climate and tree size. This dataset consists of: plotinfo.csv, which contains basic attribute information for the field plots where the data were collected; seeddata.csv, which contains the data for seeds collected (how many, what type, etc.); trapxycoord.csv, which contains location and identific
By
Western Ecological Research Center (WERC)

Seedling and tree data from Sequoia National Park and Yosemite National Park

These tables include data from 25 long-term forest plots located in either Sequoia or Yosemite national park. Trees in these plots (established between 1982 and 2001) are censused annually for mortality and measured for diameter every 4 to 6 years. Plots were mostly 1 hectare (ha) in size (range 0.9 - 2.5 ha) and contained at least two 25 by 25 meter seedling sub-plots to monitor natural seedling
By
Western Ecological Research Center (WERC)

Tree mortality in Sequoia National Park from 2004 to 2007 and during severe drought in 2014 to 2017

These data describe tree mortality and the factors associated with tree mortality for a variety of plots in Sequoia National Park. Most of the data were collected between 2014 and 2017 (during an extremely severe drought), along with some comparison data from 2004 to 2007. These data support the following publication: Stephenson, N.L., Das, A.J., Ampersee, N.J., Bulaon, B.M., and Yee, J.L.,
By
Western Ecological Research Center (WERC)

Sequoia foliage dieback data from Sequoia National Park

These datasets provide spatially-explicit estimates of the magnitude of giant sequoia foliage dieback along selected trail corridors in Sequoia and Kings Canyon national parks, California, from 2014 through 2017. They additionally provide giant sequoia tree-ring measurements, through the year 1989, for two locations in the Giant Forest grove, Sequoia National Park, California.
By
Western Ecological Research Center (WERC)

Mortality factors for dead trees from a subset of plots from the Sierra Nevada Forest Dynamics Plot Network from 1998 to 2010

This dataset was used to summarize and analyze the mortality factors recorded on dead trees in the Sierra Nevada Forest Dynamics Plot Network, which is managed by the Sequoia and Kings Canyon Field station of the U.S. Geological Survey's Western Ecological Research Center. Each row of the dataset represents an individual dead tree. These are dead trees that were recorded in the network from 1998 t
By
Western Ecological Research Center (WERC)
Filter Total Items: 41

Forest resistance to extended drought enhanced by prescribed fire in low elevation forests of the Sierra Nevada

Prescribed fire reduces fire hazards by removing dead and live fuels (small trees and shrubs). Reductions in forest density following prescribed fire treatments (often in concert with mechanical treatments) may also lessen competition so that residual trees might be more likely to survive when confronted with additional stressors, such as drought. The current evidence for these effects is mixed an
By
Ecosystems, Western Ecological Research Center (WERC)

Nonlinear shifts in infectious rust disease due to climate change

Range shifts of infectious plant disease are expected under climate change. As plant diseases move, emergent abiotic-biotic interactions are predicted to modify their distributions, leading to unexpected changes in disease risk. Evidence of these complex range shifts due to climate change, however, remains largely speculative. Here, we combine a long-term study of the infectious tree disease, whit
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

Mapping the vulnerability of giant sequoias after extreme drought in California using remote sensing

Between 2012 and 2016, California suffered one of the most severe droughts on record. During this period Sequoiadendron giganteum (giant sequoias) in the Sequoia and Kings Canyon National Parks (SEKI), California, USA experienced canopy water content (CWC) loss, unprecedented foliage senescence, and, in a few cases, death. We present an assessment of the vulnerability of giant sequoia populations
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

Continent-wide tree fecundity driven by indirect climate effects

Indirect climate effects on tree fecundity that come through variation in size and growth (climate-condition interactions) are not currently part of models used to predict future forests. Trends in species abundances predicted from meta-analyses and species distribution models will be misleading if they depend on the conditions of individuals. Here we find from a synthesis of tree species in North
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

Why is tree drought mortality so hard to predict?

Widespread tree mortality following droughts has emerged as an environmentally and economically devastating ‘ecological surprise’. It is well established that tree physiology is important in understanding drought-driven mortality; however, the accuracy of predictions based on physiology alone has been limited. We propose that complicating factors at two levels stymie predictions of drought-driven
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

Seed production patterns of surviving Sierra Nevada conifers show minimal change following drought

Reproduction is a key component of ecological resilience in forest ecosystems, so understanding how seed production is influenced by extreme drought is key to understanding forest recovery trajectories. If trees respond to mortality-inducing drought by preferentially allocating resources for reproduction, the recovery of the stand to pre-drought conditions may be enhanced accordingly. We used a 20
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

Effects of postfire climate and seed availability on postfire conifer regeneration

Large, severe fires are becoming more frequent in many forest types across the western United States and have resulted in tree mortality across tens of thousands of hectares. Conifer regeneration in these areas is limited because seeds must travel long distances to reach the interior of large burned patches and establishment is jeopardized by increasingly hot and dry conditions. To better inform p
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

Compounding effects of white pine blister rust, mountain pine beetle, and fire threaten four white pine species

Invasive pathogens and bark beetles have caused precipitous declines of various tree species around the globe. Here, we characterized long‐term patterns of mountain pine beetle (Dendroctonus ponderosae; MPB) attacks and white pine blister rust, an infectious tree disease caused by the pathogen, Cronartium ribicola. We focused on four dominant white pine host species in Sequoia and Kings Canyon Nat
By
Ecosystems, Climate Research and Development Program, Western Ecological Research Center (WERC)

Mortality predispositions of conifers across western USA

Conifer mortality rates are increasing in western North America, but the physiological mechanisms underlying this trend are not well understood.We examined tree‐ring‐based radial growth along with stable carbon (C) and oxygen (O) isotope composition (δ13C and δ18O, respectively) of dying and surviving conifers at eight old‐growth forest sites across a strong moisture gradient in the western USA to
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Fort Collins Science Center, Western Ecological Research Center (WERC)

Height-related changes in forest composition, not tree vulnerability, explain increasing mortality with height during an extreme drought

Recently, Stovall et al.1 (hereafter SSY) showed that during an extreme drought, remotely sensed mortality of tall trees was more than double that of short trees. They interpreted this to be a consequence of inherently greater hydraulic vulnerability of tall trees, and suggested that tall-tree vulnerability should thus generalize more broadly. Here we reassess their conclusions using contemporan
By
Ecosystems, Climate Research and Development Program, Land Change Science Program, Western Ecological Research Center (WERC)

The Fire and Tree Mortality Database, for empirical modeling of individual tree mortality after fire

Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records
By
Ecosystems, Climate Research and Development Program, Western Ecological Research Center (WERC)

Coming to terms with the new normal: Forest health in the Sierra Nevada

The vast conifer forests of California’s Sierra Nevada range inspire awe and create lasting memories. The size and longevity of these trees make them seem both otherworldly and everlasting. Indeed, their grandeur is such that visitors may not appreciate how these forests are connected to the larger landscape, and so there is little understanding that something as common as a drought could lead to
By
Ecosystems, Western Ecological Research Center (WERC)
link

Investigating drivers of tree mortality in western forests

This article is part of the Spring 2017 issue of the Earth Science Matters Newsletter. 

Read Article
link

Climate effects on western US forests

This article is part of the Fall 2014 issue of the Earth Science Matters Newsletter. 

Read Article

Science and Products