Robert Mickler - Academia.edu (original) (raw)

Papers by Robert Mickler

Ecological Studies, 2000

... John Lun. IV. ... We are grateful for the insight provided by Phil Wargo, Chip Scott, Keith J... more ... John Lun. IV. ... We are grateful for the insight provided by Phil Wargo, Chip Scott, Keith Jensen, Robert Long, Joanne Rebbeck, Kevin Smith, Jud Isebrands, Lew Ohmann, Rolfe Leary, Mike Vasievich, John Zasada, Alan Lucier, Eric Vance, Alan Ek, David Shriner, Steve Rawlins ...

Forest Ecology and Management, 2014

This paper provides an overview and summary of the current state of knowledge regarding critical ... more This paper provides an overview and summary of the current state of knowledge regarding critical atmospheric processes that affect the distribution and concentrations of greenhouse gases and aerosols emitted from wildland fires or produced through subsequent chemical reactions in the atmosphere. These critical atmospheric processes include the dynamics of plume rise, chemical reactions involving smoke plume constituents, the long-range transport of smoke plumes, and the potential transport of gases and aerosols from wildland fires into the stratosphere. In the area of plume-rise dynamics, synthesis information is provided on (1) the relevance of plume height for assessing impacts of gases and aerosol from wildland fires on the climate system, (2) recent scientific advances in understanding the role of multiple updraft cores in plume behavior, and (3) some of the current modeling tools and remote sensing monitoring techniques available for predicting and measuring smoke plume heights. In the area of atmospheric chemistry associated with wildland fire emissions, synthesis information is provided on what is currently known about the atmospheric fate of wildland fire smoke-plume constituents and the relationship of their atmospheric chemistry to radiative forcing. Synthesis information related to long-range atmospheric transport of wildland fire emissions is presented and summarizes many of the recent published observational and modeling studies that provide clear evidence of intercontinental, continental, and regional transport of North American fire emissions, including black carbon, to locations far-removed from the fire-event locations. Recent studies are also highlighted that examined the significance of troposphere-stratosphere exchange processes, which can result in the transport of greenhouse gases and aerosols from North American wildland fires into the stratosphere where they can remain for very long periods of time and alter the radiative balance and typical chemical reactions that occur there. Finally, specific research gaps and needs related to plume dynamics, atmospheric transport and deposition processes, and the atmospheric chemistry of wildland fire emissions are identified and discussed.

Developments in hyperspectral remote sensing techniques during the last decade have enabled the u... more Developments in hyperspectral remote sensing techniques during the last decade have enabled the use of narrowband indices to evaluate the role of forest ecosystem variables in estimating carbon (C) fluxes. In this study, narrowband bio-indicators derived from EO-1 Hyperion data were investigated to determine whether they could capture the temporal variation and estimate the spatial variability of forest C fluxes derived from eddy covariance tower data. Nineteen indices were divided into four categories of optical indices: broadband, chlorophyll, red edge, and light use efficiency. Correlation tests were performed between the selected vegetation indices, gross primary production (GPP), and ecosystem respiration (Re). Among the 19 indices, five narrowband indices (Chlorophyll Index RedEdge 710, scaled photochemical reflectance index (SPRI)*enhanced vegetation index (EVI), SPRI*normalized difference vegetation index (NDVI), MCARI/OSAVI[705, 750] and the Vogelmann Index), and one broad band index (EVI) had R-squared values with a good fit for GPP and Re. The SPRI*NDVI has the highest significant coefficients of determination OPEN ACCESS Remote Sens. 2014, 6 8987 with GPP and Re (R 2 = 0.86 and 0.89, p < 0.0001, respectively). SPRI*NDVI was used in atmospheric inverse modeling at regional scales for the estimation of C fluxes. We compared the GPP spatial patterns inversed from our model with corresponding results from the Vegetation Photosynthesis Model (VPM), the Boreal Ecosystems Productivity Simulator model, and MODIS MOD17A2 products. The inversed GPP spatial patterns from our model of SPRI*NDVI had good agreement with the output from the VPM model. The normalized difference nitrogen index was well correlated with measured C net ecosystem exchange. Our findings indicated that narrowband bio-indicators based on EO-1 Hyperion images could be used to predict regional C flux variations for Northeastern China's temperate broad-leaved Korean pine forest ecosystems.

Fire managers in the Coastal Plain of the Southeastern United States use prescribed burning as a ... more Fire managers in the Coastal Plain of the Southeastern United States use prescribed burning as a tool to reduce fuel loads in a variety of vegetation types, many of which have elevated fuel loads due to a history of fire suppression. While standardized fuel models are useful in prescribed burn planning, those models do not quantify site-specific fuel loads that reflect land use change, natural disturbances, and previous management. Furthermore, data on the fuel consumed during prescribed burning are generally unavailable. In an effort to accurately measure and map fuel loading and consumption at a site-specific level, fuels and vegetative communities were characterized in five burn compartments at the Air Force Dare County Bombing Range and Alligator River National Wildlife Refuge in eastern North Carolina. Aerial photography, digital softcopy photogrammetry, and GIS were used to map vegetation to the alliance level of the National Vegetation Classification System (NVCS). Within eac...

Wildland fuels have been accumulating in the United States during at least the past half-century ... more Wildland fuels have been accumulating in the United States during at least the past half-century due to wildland fire management practices and policies. The additional fuels contribute to intense fire behavior, increase the costs of wildland fire control, and contribute to the degradation of local and regional air quality. The management of prescribed and wildland fire on Federal, State, and private lands pose critical challenges for the characterization of preburn fire fuels and postburn carbon consumption assessments, predicting smoke trajectories and concentrations, and modeling air quality emissions. Prescribed and wildland fires are both important sources of airborne fine particulate matter (PM2.5) and ozone (O3) precursors such as nonmethane volatile (VOCs) and semivolatile organic compounds (SVOCs), nitrogen oxides (NOx), carbon monoxide (CO), and methane (CH4). We quantified pre- and postburn belowground and aboveground biomass to determine fuel consumption for fine and coar...

The management of prescribed and wildland fire on federal, state, and private lands with deep org... more The management of prescribed and wildland fire on federal, state, and private lands with deep organic soils pose critical challenges for ecosystem management, smoke dispersion, and the protection of private property and human life. Several regions in the US contain significant areas of deep organic soils, the boreal forests of Alaska and the northeastern US, the peat bogs in the glaciated northeast and Great Lakes, and the pocosins in the southeastern and Gulf coasts.

Fire-adapted forest ecosystems make up 95 percent of the historic Coastal Plain vegetation types ... more Fire-adapted forest ecosystems make up 95 percent of the historic Coastal Plain vegetation types in the Southeastern United States. Fire suppression over the last century has altered the species composition of these ecosystems, increased fuel loads, and increased wildfire risk. Prescribed fire is one management tool used to reduce fuel loading and restore fire-adapted species, but little information exists on the presettlement extent and location of fire-dependent ecosystems at a level of detail useful to guide land management decisions at the local spatial scale. In an effort to close this knowledge gap, the principles of landscape fire ecology have been applied to develop a detailed presettlement fire regime map for ~200,000 acres of Coastal Plain ecosystems. Factors evaluated include the effects of fire compartment size in the original landscape, fire barriers, fire filters, prevailing wind direction during fire season, topographic and soil factors affecting fire intensity, fire ...

Fire-adapted forest ecosystems make up a large component of historic coastal plain vegetation typ... more Fire-adapted forest ecosystems make up a large component of historic coastal plain vegetation types in the southeastern US. Fire suppression over the last century has resulted in elevated fuel loads in these forests, increasing wildfire risk and stressing the resources of land managers. Prescribed fire is a potential management tool to reduce fuel loading, but accurate data on fuel loading and fuel consumption is not currently available. Generating this data is a necessary step in accomplishing fuel reduction management goals. In this study we use 1:6000 color infrared aerial photography and softcopy photogrammetry techniques to map National Vegetation Classification System (NVCS) ecological associations. Next, we use USDA Forest Service Forest Inventory and Analysis (FIA) phase 3 protocol field plots to characterize the levels of 1, 10, and 100 hour fuels specific to each NVCS association. In addition, FIA phase 2 protocol plots are used to characterize live and standing dead tree ...

Carbon Balance and Management

Background One of the scientific challenges of understanding climate change has been determining ... more Background One of the scientific challenges of understanding climate change has been determining the important drivers and metrics of global carbon (C) emissions and C cycling in tropical, subtropical, boreal, subarctic, and temperate peatlands. Peatlands account for 3% of global land cover, yet contain a major reservoir of 550 gigatons (Gt) of soil C, and serve as C sinks for 0.37 Gt of carbon dioxide (CO2) a year. In the United States, temperate peatlands are estimated to store 455 petagrams of C (PgC). There has been increasing interest in the role of wildfires in C cycling and altering peatlands from C sinks to major C sources. We estimated above- and below-ground C emissions from the Pains Bay Fire, a long-duration wildfire (112 days; 18,329 ha) that burned a coastal peatland in eastern North Carolina, USA. Results Soil C emissions were estimated from pre- and post-burn Light Detection and Ranging (LIDAR) soil elevation data, soils series and C content mapping, remotely sensed ...

Remote Sensing

The photochemical reflectance index (PRI) has been suggested as an indicator of light use efficie... more The photochemical reflectance index (PRI) has been suggested as an indicator of light use efficiency (LUE), and for use in the improvement of estimating gross primary production (GPP) in LUE models. Over the last two decades, solar-induced fluorescence (SIF) observations from remote sensing have been used to evaluate the distribution of GPP over a range of spatial and temporal scales. However, both PRI and SIF observations have been decoupled from photosynthesis under a variety of non-physiological factors, i.e., sun-view geometry and environmental variables. These observations are important for estimating GPP but rarely reported in the literature. In our study, multi-angle PRI and SIF observations were obtained during the 2018 growing season in a maize field. We evaluated a PRI-based LUE model for estimating GPP, and compared it with the direct estimation of GPP using concurrent SIF measurements. Our results showed that the observed PRI varied with view angles and that the averaged...

Journal of Geophysical Research: Biogeosciences

Water

Drought impacts carbon and water fluxes of terrestrial ecosystems, which are strongly coupled. Ho... more Drought impacts carbon and water fluxes of terrestrial ecosystems, which are strongly coupled. However, the magnitudes of response of carbon and water fluxes to drought are dependent on many processes, which are more complex than previously expected. Southern China experienced regional climatic perturbation events in the past decade and a two-year drought in 2009-2010. We used a terrestrial ecosystem model coupled with remotely sensed observations and metrological data to simulate the variations of net primary productivity (NPP), evapotranspiration (ET), and water-use efficiency (WUE) (i.e., NPP/ET) in southwestern China during the period 2001-2010. Using the standard precipitation index (SPI) classifying different drought stresses, we also quantified the effect of drought on the ecosystem by comparing changes in modelled estimates of monthly WUE, NPP and ET under normal (i.e., baseline) and drought conditions (i.e., 2009 and 2010). The results indicated that NPP and ET showed synchronized declines in drought periods, with time-lag effects. Furthermore, drought-induced NPP decline was larger than ET reduction. An increasing trend in WUE from the moderate to extreme drought classes occurred not only in baseline conditions but also in drought conditions. Especially in the extreme drought period (January, 2010), WUE for the forest ecosystem typically showed a positive response to drought, indicating a drought-resilient forest ecosystem. Our study has important implications for understanding climate extreme effects on the carbon and water cycle of the forest ecosystem.