Walter Shortle - Academia.edu (original) (raw)

Papers by Walter Shortle

Pioneering research by Alex L. Shigo and his associates has produced a series of pictorial guidel... more Pioneering research by Alex L. Shigo and his associates has produced a series of pictorial guidelines to provide a better understanding of how trees respond to wounding and subsequent microbial infections that lead to wood decay. The purpose of this paper is to visually summarize through the use of 96 color photographs and illustrations, the varied patterns of wood discoloration and decay observed in the dissection of thousands of trees. This information has served as a conceptual framework for understanding the biochemical processes that limit the spread of wood-destroying infections initiated by wounding during the maturation of all trees. This understanding has helped those who work with forests, trees, and wood to resolve practical problems and improve the health and productivity of trees and forests.

Environmental and Experimental Botany, Nov 1, 2009

Calcium cycling plays a key role in the health and productivity of red spruce forests in the nort... more Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca 2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of environmental change due to acidic deposition or forest management practices. We compared the effects of Ca fertilization treatment on Ca concentration in wood and Ca and oxalate (Ox) concentration in foliage at two locations with different initial concentrations of Ca in the soil. We found greater amounts of Ca in wood from the high-Ca location than from the low-Ca location. Ca concentration was greater in wood formed in the 1970s than for wood formed in the 1980s, the outermost decadal band in these samples. The Ca-treatment was detected as an increased concentration of Ca in the 1970s and 1980s decadal bands. We also found that variation in Ca and Ox in foliage was essentially stoichiometric. The appearance and response to chemical tests of crystals in foliage were consistent with identification as calcium oxalate. The increased Ca in wood after Ca-treatment of the soil supports the use of dendrochemistry of base cations to investigate environmental change. However, differences in Ca concentration between the two outermost decadal bands of wood illustrate that internal processes of translocation and storage also affect Ca concentration. Calcium oxalate production in foliage diverts carbon from ordinary biosynthesis and energy-yielding processes. This sequestration, shedding, and decomposition of foliage may represent a significant and under-recognized contribution to carbon and Ca cycling.

Canadian Journal of Forest Research, Jun 28, 2007

The decay of coarse woody debris is a key component in the formation of forest soil and in the bi... more The decay of coarse woody debris is a key component in the formation of forest soil and in the biogeochemical cycles of Ca and Mg. We tracked changes in density and concentration of Ca and Mg in sapwood of red maple (Acer rubrum L.), red spruce (Picea rubens Sarg.), paper birch (Betula papyrifera Marsh.), and eastern hemlock (Tsuga canadensis (L.) Carr.) in Maine and New Hampshire. We repeatedly sampled 10 logs of each combination of tree species and location at the time of felling and at 2-year intervals for 6 years (birch and hemlock) or 8 years (spruce and maple). We found that density loss was essentially linear for the time period investigated, with birch and maple sapwood decaying at faster rates than spruce and hemlock. Repeated-measures analysis and regression modeling of log-transformed concentrations indicated a significant accumulation of Ca for sapwood of all tree species at both locations (30%-90% increase after 6-8 years of ground contact). Regression estimates of Mg concentration in spruce and maple declined about 20% during the 8 years of ground contact. There was no significant trend for Mg concentration in birch and hemlock. Variation in decay rates and trends in Ca and Mg concentration may be due to differences in sapwood quality, the community of wood decay fungi and associated organisms, or to abiotic conditions.

Environmental science & technology, Jan 23, 2015

A consistent decreasing trend in acidic deposition levels over the past several decades has led t... more A consistent decreasing trend in acidic deposition levels over the past several decades has led to partial chemical recovery of surface waters. However, depletion of soil Ca from acidic deposition has slowed surface water recovery and led to the impairment of both aquatic and terrestrial ecosystems. Nevertheless, documentation of acidic deposition effects on soils has been limited, and little is known regarding the response of soils to ongoing declines in acidic deposition. To address this problem, resampling of soils in eastern Canada and the northeastern U.S. was done at 27 sites exposed to reductions in wet SO42- deposition of 5.7% to 76%, over intervals of 8 to 24 years. Decreases of exchangeable Al in the O horizon, and increases in pH in the O and B horizons were seen at a majority of sites. Among all sites, reductions in SO42- deposition were positively correlated with base saturation (P < 0.01), and negatively correlated with exchangeable Al (P < 0.05) in the O horizon...

Phytopathology

SHIGO, A. L., and W. C. SHORTLE. 1979. Compartmentalization of discolored wood in heartwook of re... more SHIGO, A. L., and W. C. SHORTLE. 1979. Compartmentalization of discolored wood in heartwook of red oak. Phytopathology 69:710-711.

Studies of half-sib progeny tests of sweetgum (Liquidambar styraciflua) and clonal plantings of e... more Studies of half-sib progeny tests of sweetgum (Liquidambar styraciflua) and clonal plantings of eastern cottonwood (Populus deltoides) in Mississippi indicate that rate of wound closure and size of discolored columns associated with the wounds are both heritable traits. Both are independent of stem diameter, which was used as a measure of tree vigor in these studies. Selection for rate of closure would not be useful, but selection for compartmentalization of discoloration and decay resulting from wounding would be valuable in forest and amenity trees and could be applied immediately to existing improvement programs for these species.

A simple and fast method for extraction of major inorganic ions (Ca, Mg, Mn, K, and P) and cellul... more A simple and fast method for extraction of major inorganic ions (Ca, Mg, Mn, K, and P) and cellular polyamines from small quantities of wood and woody plant tissues is described. The method involves repeated freezing and thawing of samples instead of homogenization or wet ash digestion. The efficiency of extraction of both polyamines and inorganic ions by these methods was compared for 10 different tissues. Drillbit shavings generated from wood disks or increment cores were also compared with ground wood as the starting material for ion analysis by this newly developed method of freeze-thawing. Direct use of drillbit shavings circumvents the need for making wood chips by hand and grinding in a Wiley mill. Moreover, freeze-thawing not only eliminates the need for various tissue homogenizers but is also simple enough that a large number of samples can be processed simultaneously. This method seems to be particularly useful with extremely small samples of 25 mg or less, e.g., shavings from individual growth rings of mature trees and differentiating tissues grown in vitro.

The requirement for polyamines in the proliferation of cells was first demonstrated in bacteria (... more The requirement for polyamines in the proliferation of cells was first demonstrated in bacteria (3). While significant progress has been made in this field using animal cell cultures, only preliminary studies have been reported with plant tissues. Serafini-Fracassini et al. showed a marked increase in polyamine synthesis early during the G 1 phase, concomitant with the synthesis of RNA, following the break of dormancy in Helianthus tuberosus tuber tissue. A second phase of polyamine accumulation began during the progression of S phase. Torrigiani et al. and Phillips et al. later showed that all major polyamines peaked during the G 1 phase. This increase in polyamines was preceded by increased ODC and ADC activities.

Three major needs &t to k t t e r relate tree biology r e a r c h to practical agroforeshy (L a m... more Three major needs &t to k t t e r relate tree biology r e a r c h to practical agroforeshy (L a m 1984). The first need is to identify the specific, desired prduct to k yielded from the forest. Valid and appropriate management techniques to yield one prduct may not be appropriate to yield a different product, even from the same species of trees. The second need i s to s y n t h e s d the relevant scientific and technical howl-e d ~ . Frequently, the relevant knowledge to effectively yield a prduct needs to be integrated across a wide range of resources. The third need is to develop a comprehensive life history of the crop tree species. Tree life history and biology indudes the growth and the decay procesw that are common to all mature trpes. The opposing processes of growth and decay occur simultaneously within a living tree for long periods of time. However, the mere sunrival of damaged and diseased b e s in the forest can interfere with the yield of the desired s t e m w d product...

International Biodeterioration, 1988

343 baternational Bioth,terioration 0265-3036/88/$03.50© 1988 Elsevier Science Publishers Ltd, En... more 343 baternational Bioth,terioration 0265-3036/88/$03.50© 1988 Elsevier Science Publishers Ltd, England. Printed in Great Britain. 344 t~ Taylor et al.

of Maine for providing research locations. We thank Helen Thompson and Debbie Muccio (Northeaster... more of Maine for providing research locations. We thank Helen Thompson and Debbie Muccio (Northeastern Area, State and Private Forestry) for their help. T he ice storm of January 1998 in the northeastern United States and adjacent Canada was an extreme example of severe weather that injures trees every year. Broken branches, split branch forks, and snapped stems are all examples of storm injury. Immediately following the storm, broken stems and hanging branches presented a safety hazard. In addition to safety, landowners and foresters were concerned about the amount of damage — defined as the loss of economic value of wood products — that would result from storm injury. In response to this concern about hardwood quality, we began a 5-year research program to identify patterns of storm injury and tree response to wounding. During the first 2 years of research, we methodically dissected 40 hardwood trees that had been injured in the 1998 ice storm and earlier storms. Particular attention ...

New ideas and new tools give the arborist new op- portunities to better assess the hazard potenti... more New ideas and new tools give the arborist new op- portunities to better assess the hazard potential of decayed trees. Before using electronics to help detect decay in trees, today's arborist must first train the "mind's eye" to "see" in- side the living tree. A model system called CODIT has been developed to explain the patterns of discoloration and decay

Many materials were used in and on experimental- ly inflicted wounds in many studies over a 13-ye... more Many materials were used in and on experimental- ly inflicted wounds in many studies over a 13-year period. No material prevented decay. The individual tree had a greater ef- fect on the wound than the treatments. Some individual trees of a species closed and compartmentalized wounds rapidly and effectively, regardless of treatment, while other trees did not close and compartmentalize

Pioneering research by Alex L. Shigo and his associates has produced a series of pictorial guidel... more Pioneering research by Alex L. Shigo and his associates has produced a series of pictorial guidelines to provide a better understanding of how trees respond to wounding and subsequent microbial infections that lead to wood decay. The purpose of this paper is to visually summarize through the use of 96 color photographs and illustrations, the varied patterns of wood discoloration and decay observed in the dissection of thousands of trees. This information has served as a conceptual framework for understanding the biochemical processes that limit the spread of wood-destroying infections initiated by wounding during the maturation of all trees. This understanding has helped those who work with forests, trees, and wood to resolve practical problems and improve the health and productivity of trees and forests.

Environmental and Experimental Botany, Nov 1, 2009

Calcium cycling plays a key role in the health and productivity of red spruce forests in the nort... more Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca 2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of environmental change due to acidic deposition or forest management practices. We compared the effects of Ca fertilization treatment on Ca concentration in wood and Ca and oxalate (Ox) concentration in foliage at two locations with different initial concentrations of Ca in the soil. We found greater amounts of Ca in wood from the high-Ca location than from the low-Ca location. Ca concentration was greater in wood formed in the 1970s than for wood formed in the 1980s, the outermost decadal band in these samples. The Ca-treatment was detected as an increased concentration of Ca in the 1970s and 1980s decadal bands. We also found that variation in Ca and Ox in foliage was essentially stoichiometric. The appearance and response to chemical tests of crystals in foliage were consistent with identification as calcium oxalate. The increased Ca in wood after Ca-treatment of the soil supports the use of dendrochemistry of base cations to investigate environmental change. However, differences in Ca concentration between the two outermost decadal bands of wood illustrate that internal processes of translocation and storage also affect Ca concentration. Calcium oxalate production in foliage diverts carbon from ordinary biosynthesis and energy-yielding processes. This sequestration, shedding, and decomposition of foliage may represent a significant and under-recognized contribution to carbon and Ca cycling.

Canadian Journal of Forest Research, Jun 28, 2007

The decay of coarse woody debris is a key component in the formation of forest soil and in the bi... more The decay of coarse woody debris is a key component in the formation of forest soil and in the biogeochemical cycles of Ca and Mg. We tracked changes in density and concentration of Ca and Mg in sapwood of red maple (Acer rubrum L.), red spruce (Picea rubens Sarg.), paper birch (Betula papyrifera Marsh.), and eastern hemlock (Tsuga canadensis (L.) Carr.) in Maine and New Hampshire. We repeatedly sampled 10 logs of each combination of tree species and location at the time of felling and at 2-year intervals for 6 years (birch and hemlock) or 8 years (spruce and maple). We found that density loss was essentially linear for the time period investigated, with birch and maple sapwood decaying at faster rates than spruce and hemlock. Repeated-measures analysis and regression modeling of log-transformed concentrations indicated a significant accumulation of Ca for sapwood of all tree species at both locations (30%-90% increase after 6-8 years of ground contact). Regression estimates of Mg concentration in spruce and maple declined about 20% during the 8 years of ground contact. There was no significant trend for Mg concentration in birch and hemlock. Variation in decay rates and trends in Ca and Mg concentration may be due to differences in sapwood quality, the community of wood decay fungi and associated organisms, or to abiotic conditions.

Environmental science & technology, Jan 23, 2015

A consistent decreasing trend in acidic deposition levels over the past several decades has led t... more A consistent decreasing trend in acidic deposition levels over the past several decades has led to partial chemical recovery of surface waters. However, depletion of soil Ca from acidic deposition has slowed surface water recovery and led to the impairment of both aquatic and terrestrial ecosystems. Nevertheless, documentation of acidic deposition effects on soils has been limited, and little is known regarding the response of soils to ongoing declines in acidic deposition. To address this problem, resampling of soils in eastern Canada and the northeastern U.S. was done at 27 sites exposed to reductions in wet SO42- deposition of 5.7% to 76%, over intervals of 8 to 24 years. Decreases of exchangeable Al in the O horizon, and increases in pH in the O and B horizons were seen at a majority of sites. Among all sites, reductions in SO42- deposition were positively correlated with base saturation (P < 0.01), and negatively correlated with exchangeable Al (P < 0.05) in the O horizon...

Phytopathology

SHIGO, A. L., and W. C. SHORTLE. 1979. Compartmentalization of discolored wood in heartwook of re... more SHIGO, A. L., and W. C. SHORTLE. 1979. Compartmentalization of discolored wood in heartwook of red oak. Phytopathology 69:710-711.

Studies of half-sib progeny tests of sweetgum (Liquidambar styraciflua) and clonal plantings of e... more Studies of half-sib progeny tests of sweetgum (Liquidambar styraciflua) and clonal plantings of eastern cottonwood (Populus deltoides) in Mississippi indicate that rate of wound closure and size of discolored columns associated with the wounds are both heritable traits. Both are independent of stem diameter, which was used as a measure of tree vigor in these studies. Selection for rate of closure would not be useful, but selection for compartmentalization of discoloration and decay resulting from wounding would be valuable in forest and amenity trees and could be applied immediately to existing improvement programs for these species.

A simple and fast method for extraction of major inorganic ions (Ca, Mg, Mn, K, and P) and cellul... more A simple and fast method for extraction of major inorganic ions (Ca, Mg, Mn, K, and P) and cellular polyamines from small quantities of wood and woody plant tissues is described. The method involves repeated freezing and thawing of samples instead of homogenization or wet ash digestion. The efficiency of extraction of both polyamines and inorganic ions by these methods was compared for 10 different tissues. Drillbit shavings generated from wood disks or increment cores were also compared with ground wood as the starting material for ion analysis by this newly developed method of freeze-thawing. Direct use of drillbit shavings circumvents the need for making wood chips by hand and grinding in a Wiley mill. Moreover, freeze-thawing not only eliminates the need for various tissue homogenizers but is also simple enough that a large number of samples can be processed simultaneously. This method seems to be particularly useful with extremely small samples of 25 mg or less, e.g., shavings from individual growth rings of mature trees and differentiating tissues grown in vitro.

The requirement for polyamines in the proliferation of cells was first demonstrated in bacteria (... more The requirement for polyamines in the proliferation of cells was first demonstrated in bacteria (3). While significant progress has been made in this field using animal cell cultures, only preliminary studies have been reported with plant tissues. Serafini-Fracassini et al. showed a marked increase in polyamine synthesis early during the G 1 phase, concomitant with the synthesis of RNA, following the break of dormancy in Helianthus tuberosus tuber tissue. A second phase of polyamine accumulation began during the progression of S phase. Torrigiani et al. and Phillips et al. later showed that all major polyamines peaked during the G 1 phase. This increase in polyamines was preceded by increased ODC and ADC activities.

Three major needs &t to k t t e r relate tree biology r e a r c h to practical agroforeshy (L a m... more Three major needs &t to k t t e r relate tree biology r e a r c h to practical agroforeshy (L a m 1984). The first need is to identify the specific, desired prduct to k yielded from the forest. Valid and appropriate management techniques to yield one prduct may not be appropriate to yield a different product, even from the same species of trees. The second need i s to s y n t h e s d the relevant scientific and technical howl-e d ~ . Frequently, the relevant knowledge to effectively yield a prduct needs to be integrated across a wide range of resources. The third need is to develop a comprehensive life history of the crop tree species. Tree life history and biology indudes the growth and the decay procesw that are common to all mature trpes. The opposing processes of growth and decay occur simultaneously within a living tree for long periods of time. However, the mere sunrival of damaged and diseased b e s in the forest can interfere with the yield of the desired s t e m w d product...

International Biodeterioration, 1988

343 baternational Bioth,terioration 0265-3036/88/$03.50© 1988 Elsevier Science Publishers Ltd, En... more 343 baternational Bioth,terioration 0265-3036/88/$03.50© 1988 Elsevier Science Publishers Ltd, England. Printed in Great Britain. 344 t~ Taylor et al.

of Maine for providing research locations. We thank Helen Thompson and Debbie Muccio (Northeaster... more of Maine for providing research locations. We thank Helen Thompson and Debbie Muccio (Northeastern Area, State and Private Forestry) for their help. T he ice storm of January 1998 in the northeastern United States and adjacent Canada was an extreme example of severe weather that injures trees every year. Broken branches, split branch forks, and snapped stems are all examples of storm injury. Immediately following the storm, broken stems and hanging branches presented a safety hazard. In addition to safety, landowners and foresters were concerned about the amount of damage — defined as the loss of economic value of wood products — that would result from storm injury. In response to this concern about hardwood quality, we began a 5-year research program to identify patterns of storm injury and tree response to wounding. During the first 2 years of research, we methodically dissected 40 hardwood trees that had been injured in the 1998 ice storm and earlier storms. Particular attention ...

New ideas and new tools give the arborist new op- portunities to better assess the hazard potenti... more New ideas and new tools give the arborist new op- portunities to better assess the hazard potential of decayed trees. Before using electronics to help detect decay in trees, today's arborist must first train the "mind's eye" to "see" in- side the living tree. A model system called CODIT has been developed to explain the patterns of discoloration and decay

Many materials were used in and on experimental- ly inflicted wounds in many studies over a 13-ye... more Many materials were used in and on experimental- ly inflicted wounds in many studies over a 13-year period. No material prevented decay. The individual tree had a greater ef- fect on the wound than the treatments. Some individual trees of a species closed and compartmentalized wounds rapidly and effectively, regardless of treatment, while other trees did not close and compartmentalize