John R. Butnor

John R. Butnor
US Forest Service | FS · Southern Research Station

About

85
Publications
14,411
Reads
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2,358
Citations
Citations since 2017
18 Research Items
882 Citations
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2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
Additional affiliations
October 1997 - present
US Forest Service
Position
  • Plant Physiologist

Publications

Publications (85)
Preprint
Noninvasive and nondestructive root phenotyping techniques under field conditions are sorely needed to advance plant root science. Soil polarization measured by electrical capacitance (ECsoil) has the potential to meet this requirement, but whether it specifically detects root properties remains unexplored. We carried out manipulative experiments w...
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Savannas cover a fifth of the land surface and contribute a third of terrestrial net primary production, accounting for three-quarters of global area burned and more than half of global fire-driven carbon emissions1–3. Fire suppression and afforestation have been proposed as tools to increase carbon sequestration in these ecosystems2,4. A robust qu...
Article
Shifting range limits are predicted for many species as the climate warms. However, the rapid pace of climate change will challenge the natural dispersal capacity of long-lived, sessile organisms such as forest trees. Adaptive responses of populations will, therefore, depend on levels of genetic variation and plasticity for climate-responsive trait...
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Red spruce (Picea rubens Sarg.) is a coniferous tree with a highly fragmented range in eastern North American montane forests. It serves as a foundational species for many locally rare and threatened taxa and has therefore been the focus of large-scale reforestation efforts aimed at restoring these montane ecosystems, yet genetic input guiding thes...
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Purpose Electrical capacitance (EC) is widely used to measure root traits especially in hydroponic and wet soil environments, but its feasibility was recently questioned due to the possible leakage of electrical current before entering the root system. To investigate whether the current can travel deeper in woody roots, EC was evaluated in cotton (...
Article
Root water content (RWC) is a vital component in water flux in soil-plant-atmosphere continuum. Knowledge of RWC helps to better understand the root function and the soil-root interaction and improves water cycle model-ing. However, due to the lack of appropriate methods, field monitoring of RWC is seriously constrained. In this study, we used grou...
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Understanding the factors influencing the current distribution of genetic diversity across a species range is one of the main questions of evolutionary biology, especially given the increasing threat to biodiversity posed by climate change. Historical demographic processes such as population expansion or bottlenecks and decline are known to exert a...
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Root zone soil moisture (RZSM) is important in sustaining terrestrial ecosystems and water cycling. However, noninvasive mapping of RZSM remains challenging in the field, especially its spatial variability at local scales. We propose a novel method of applying ground-penetrating radar (GPR) for noninvasive determination of RZSM. First, this method...
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Prescribed fire is an essential tool that is widely used for longleaf pine (Pinus palustris Mill.) stand management; periodic burning serves to reduce competition from woody shrubs and fire-intolerant trees and enhance herbaceous diversity. Low-intensity, prescribed burning is thought to have minimal long-term impact on soil chemistry in southern p...
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Red spruce (Picea rubens) is a long-lived tree species that thrives in cool, moist environs. Its ability to adapt to rapidly changing climate is uncertain. In the southern Appalachian Mountains, red spruce reaches its greatest abundance at high elevations, but can also occur across a range of mid and lower elevations, suggesting the possibility of...
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Storage of belowground carbon (C) is an important component of total forest C. However, belowground C changes temporally due to forest growth and tree mortality (natural and via harvesting) and these fluctuations are critical for modeling C in forests under varying management regimes. To date, little progress has been made in quantifying the rate o...
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Inadequate cold tolerance of Eucalyptus spp. has limited a broader deployment beyond subtropical regions of the United States. We examined growth, photosynthetic rate, and cold tolerance of a cold-hardy Eucalypt (Eucalyptus benthamii) planted in North Carolina and compared the results with native Pinus taeda. After two growing seasons, E. benthamii...
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Aim Ground penetrating radar (GPR) as a non-invasive technique is widely used in coarse root detection. However, the applicability of the technique to detect fine roots of agricultural crops is unknown. The objective of this study was to assess the feasibility of utilizing GPR to detect fine roots in the field. Methods This study was conducted in...
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Accurate quantification of coarse roots without disturbance represents a gap in our understanding of belowground ecology. Ground penetrating radar (GPR) has shown significant promise for coarse root detection and measurement, however root orientation relative to scanning transect direction, the difficulty identifying dead root mass, and the effects...
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Autumnal leaf anthocyanin expression is enhanced following exposure to a variety of environmental stresses and may represent an adaptive benefit of protecting leaves from those stresses, thereby allowing for prolonged sugar and nutrient resorption. Past work has shown that experimentally induced sugar accumulations following branch girdling trigger...
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Longleaf pine (Pinus palustris Miller) forests in the southern United States are being restored and actively managed for a variety of goals including: forest products, biodiversity, C sequestration and forest resilience in the face of repeated disturbances from hurricanes and climate change. Managed southern pine forests can be sinks for atmospheri...
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Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally me...
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Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally me...
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Forests can partially offset greenhouse gas emissions and contribute to climate change mitigation, mainly through increases in live biomass. We quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris Mill.) forests ranging in age from 5 to 118 years located across the southeastern United States and estimated above- and belowgroun...
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Aims While lateral root mass is readily detectable with ground penetrating radar (GPR), the roots beneath a tree (below-stump) and overlapping lateral roots near large trees are problematic for surface-based antennas operated in reflection mode. We sought to determine if tree size (DBH) effects GPR root detection proximal to longleaf pine (Pinus pa...
Article
Assessment of forest carbon storage dynamics requires a variety of techniques including simulation models. We developed a hybrid model to assess the effects of silvicultural management systems on carbon (C) budgets in longleaf pine (Pinus palustris Mill.) plantations in the southeastern U.S. To simulate in situ C pools, the model integrates a growt...
Article
Ground penetrating radar (GPR) operated in reflection mode may be used to estimate lateral root biomass in forests. The technique has been very useful for quantifying belowground biomass and accounting for carbon in silivicultural studies. In general, surface-based GPR cannot detect fine roots (<2 mm diameter), vertical taproots, decayed roots or s...
Conference Paper
Background/Question/Methods Temporal and spatial quantification of coarse roots has proven to be one of the most difficult aspects of belowground ecology. Coarse roots play a significant role in belowground carbon sequestration as atmospheric CO2 levels continue to rise. Ground-penetrating radar (GPR) has been shown to be a useful, nondestructive...
Article
Soil frost depth in forest ecosystems can be variable and depends largely on early winter air temperatures and the amount and timing of snowfall. A thorough evaluation of ecological responses to seasonally frozen ground is hampered by our inability to adequately characterize the frequency, depth, duration and intensity of soil frost events. We eval...
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Longleaf pine (Pinus palustris Mill.) restoration in the southeastern United States offers opportunities for carbon (C) sequestration. Ecosystem C stocks are not well understood in longleaf pine forests, which are typically of low density and maintained by prescribed fire. The objectives of this research were to develop allometric equations for abo...
Conference Paper
Background/Question/Methods For decades, Eucalyptus sp. have been considered as candidates for use in managed forests in the southeastern United States. However, efforts have largely been stymied by periodic severe cold damage of experimental plantations; the result is that the only commercially grown Eucalyptus is in middle to southern Florida....
Conference Paper
Background/Question/Methods Restoration of longleaf pine ecosystems on military installations for protection of threatened and endangered species and for multiple ecosystem services such as carbon sequestration is a priority of military installations in the southeastern United States. Sustainably managing longleaf pine ecosystems for carbon seque...
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The magnitude of CO2 flux from soil (Fsoil) varies with primary productivity and environmental drivers of respiration, soil temperature (Tsoil) and moisture, all of which vary temporally and spatially. To quantify the sources of Fsoil variability, we first compared Fsoil of three proximate forests within 30 km of one another, ranging in age, compos...
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Uncertainty surrounds belowground plant responses to rising atmospheric CO2 because roots are difficult to measure, requiring frequent monitoring as a result of fine root dynamics and long-term monitoring as a result of sensitivity to resource availability. We report belowground plant responses of a scrub-oak ecosystem in Florida exposed to 11 yr o...
Article
Seasonal soil freezing is an important natural perturbation Common in cold regions around the world. A thorough evaluation of ecological responses to seasonally frozen ground is hampered by our inability to adequately characterize the frequency, depth, duration and intensity of soil frost events. When soil freezes, its dielectric value drops creati...
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Microbial respiration depends on microclimatic variables and carbon (C) substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon-juniper ecosystems in Southwestern North America, may affect C substrate availability in several ways; for example, via litterfall...
Chapter
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Ground-penetrating radar (GPR) is a nondestructive means of detecting buried objects with electromagnetic waves. It has been applied to detect coarse woody roots, estimate biomass, root diameter, and spatial distribution of roots. This chapter discusses the development of root assessment techniques, basic methodology, and examples of field applicat...
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Full-text available
Microbial respiration depends on microclimatic variables and carbon (C) substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon-juniper ecosystems in Southwestern North America, may affect C substrate availability in several ways; for example, via litterfall...
Conference Paper
Background/Question/Methods Seasonal soil freezing is an important natural perturbation common in cold regions around the world. It is expected that future changes in climate will alter the temporal patterns and spatial extent of seasonally frozen ground influencing physical, chemical, and biological processes in soil. A thorough evaluation of ec...
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To better understand the long-term effects of species selection and forest management practices on soil quality and soil C retention, we analyzed soil samples from an experimental planting of loblolly (Pinus taeda L.), longleaf (Pinus palustris Mill.), and slash (Pinus elliottii Engelm.) pines under different management intensities in Mississippi....
Article
The southeastern landscape is composed of agricultural and forest systems that can store carbon (C) in standing biomass and soil. Research is needed to quantify the effects of elevated atmospheric carbon dioxide (CO2) on terrestrial C dynamics including CO2 release back to the atmosphere and soil sequestration. Longleaf pine savannahs are an ecolog...
Article
The combination of biotic and abiotic factors that contribute to soil CO2 efflux can lead to large variability across spatial and temporal scales. This variability can result in uncertainty in respiration estimates; however, it can also provide insight into the primary processes affecting CO2 emissions from soil. In order to quantify the magnitude...
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A single test, including one pseudo-backcross (Pinus elliottii x Pinus taeda) x P. elliottii and open-pollinated families of the pure species progenitors, was established in North Central Florida in December 2007 to study the transfer of the fast-growing characteristics from a P. taeda L. (loblolly pine) parent into the P. elliottii Engelm. (slash...
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Full-text available
For over ten years, ground-penetrating radar (GPR) has been used in a variety of applications to detect tree roots, quantify their spatial distribution, and to estimate root diameter and biomass. Most surveys are performed once, offering a point-in-time assessment of root parameters. My own approach has been to link a small destructive sample using...
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Growth, allocation to woody root biomass, wood properties, leaf physiology, and shoot morphology were examined in a 47-year-old loblolly pine (Pinus taeda L.) density trial located in Maui, Hawaii, to determine if stands continued to carry the high density, basal area, and volume reported at younger ages and to identify potential factors controllin...
Conference Paper
Background/Question/Methods Greater carrying capacity has been reported for a variety of tree species planted in favorable, exotic environments outside their native range but mechanisms supporting greater growth potential are unclear and relevant to understanding potential climate change effects on tree growth. A longer growing season and milder...
Conference Paper
Background/Question/Methods A scrub-oak ecosystem at Kennedy Space Center, Florida was exposed to 11 years of atmospheric CO2 enrichment (ambient + 350 ppm) using open-top chambers. The objective of our study was to determine the effect of elevated CO2 on fine roots < 2 mm diameter using minirhizotrons and on coarse roots > 5 mm diameter using gro...
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Some evidence suggests that longleaf pine might be more tolerant of high winds than either slash pine (Pinus elliotii Englem.) or loblolly pine (Pinus taeda L.). We studied wind damage to these three pine species in a common garden experiment in southeast Mississippi following Hurricane Katrina, a very large, Category 3 hurricane that directly affe...
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Our objective was to test ground penetrating radar (GPR) to non-destructively estimate decay volumes in living coniferous trees. GPR is geophysical tool which uses an antenna to propagate short bursts of electromagnetic energy in solid materials and measure the two-way travel time and amplitude of reflected signals. We compared estimates of bole de...
Conference Paper
Background/Question/Methods In 1996, a long-term CO2 enrichment study was initiated in a scrub-oak ecosystem at Kennedy Space Center, Florida. The experimental design involved 16 open-top chambers that continuously received either ambient or elevated (ambient + 350 ppm) CO2 concentrations. The objective of the work presented here was to determine...
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Forests, both naturally regenerated stands and plantations are complex, long-lived systems, which can be difficult to assess and monitor over time. This is especially true of belowground biomass and internal features of trees which are inaccessible except by destructive sampling. Traditional methods are expensive, destructive, time-consuming, usual...
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Sequestering carbon (C) in forest soils can benefit site fertility and help offset greenhouse gas emissions. However, identifying soil conditions and forest management practices which best promote C accumulation remains a challenging task. We tested whether soil incorporation of masticated woody residues alters short-term C storage at forested site...
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Leaf physiology and stem growth were assessed in loblolly pine (Pinus taeda L.) in response to 10 to 11 years of treatment with weed control (W), weed control plus irrigation (WI), weed control plus irrigation and fertigation (WIF), or weed control plus irrigation, fertigation, and pest control (WIFP) to determine whether increased resource availab...
Chapter
Roots make up 5 to 45 percent of tree biomass in upland forests worldwide (Cairns et al., 1997), but estimates from urban settings are limited. Roots of eld-grown trees are difcult to assess and delineate without laborious and destructive excavations. For this reason, relative to studies on aboveground biomass, root systems have rarely been studied...
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Full-text available
Growth and distribution of coarse roots in time and space represent a gap in our understanding of belowground ecology. Large roots may play a critical role in carbon sequestration belowground. Using ground-penetrating radar (GPR), we quantified coarse-root biomass from an open-top chamber experiment in a scrub-oak ecosystem at Kennedy Space Center,...
Article
Quantifying below-ground carbon (C) allocation is particularly difficult as methods usually disturb the root-mycorrhizal-soil continuum. We reduced C allocation below ground of loblolly pine trees by: (1) physically girdling trees and (2) physiologically girdling pine trees by chilling the phloem. Chilling reduced cambium temperatures by approximat...
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The partitioning among carbon (C) pools of the extra C captured under elevated atmospheric CO2 concentration ([CO2]) determines the enhancement in C sequestration, yet no clear partitioning rules exist. Here, we used first principles and published data from four free-air CO2 enrichment (FACE) experiments on forest tree species to conceptualize the...
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Intensive management of southern pine plantations has yielded multifold increases in productivity over the last half century. The process of harvesting merchantable material and preparing a site for planting can lead to a considerable loss of organic matter. Intensively managed stands may experience more frequent disturbance as rotations decrease i...
Article
Ground-penetrating radar has been used to de- tect and map tree roots using surface-based antennas in reflection mode. On amenable soils these methods can accurately detect lateral tree roots. In some tree species (e.g. Pinus taeda, Pinus palustris), vertically orientated tap roots directly beneath the tree, comprise most of the root mass. It is di...
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Little is known about biophysical controls on soil respiration in California's Sierra Nevada old-growth, mixed-conifer forests. Using portable and automated soil respiration sampling units, we measured soil respiration rate (SRR) in three dominant patch types: closed canopy (CC), ceanothus-dominated patches (CECO), and open canopy (OC). SRR varied...
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Soil CO2 efflux is a major component of net ecosystem productivity (NEP) of forest systems. Combining data from multiple researchers for larger-scale modeling and assessment will only be valid if their methodologies provide directly comparable results. We conducted a series of laboratory and field tests to assess the presence and magnitude of soil...
Chapter
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Globally, the species most widely used for plantation forestry is loblolly pine (Pinus taeda L.). Because loblolly pine plantations are so extensive and grow so rapidly, they provide a great potential for sequestering atmospheric carbon (C). Because loblolly pine plantations are relatively simple ecosystems and because such a great volume of knowle...