The Experts below are selected from a list of 2832 Experts worldwide ranked by ideXlab platform
Robert J. Mitchell - One of the best experts on this subject based on the ideXlab platform.
-
The path back: oaks ( Quercus spp.) facilitate longleaf pine ( Pinus palustris ) seedling establishment in xeric sites
Ecosphere, 2016Co-Authors: E. Louise Loudermilk, Scott Pokswinski, Analie Barnett, J. Kevin Hiers, Joseph J. O'brien, Robert J. MitchellAbstract:Understanding plant-plant facilitation is critical for predicting how plant community func- tion will respond to changing disturbance and climate. In longleaf pine (Pinus palustris Mill.) ecosystems of the southeastern United States, understanding processes that affect pine reproduction is imperative for conservation efforts that aim to maintain ecosystem resilience across its wide geographic range and edaphic gradients. Variation in wildland fire and plant-plant interactions may be overlooked in "coarse filter" restoration management, where actions are often prescribed over a variety of ecological conditions with an assumed outcome. For example, hardwood reduction techniques are commonly deemed neces- sary for ecological restoration of longleaf pine ecosystems, as hardwoods are presumed competitors with longleaf pine seedlings. Natural regeneration dynamics are difficult to test experimentally given the in- frequent and irregular mast seed events of the longleaf pine. Using a long- term, large- scale restoration ex- periment and a long- term monitoring data site at Eglin Air Force Base, Florida (USA), this study explores the influence of native fire- intolerant oaks on longleaf regeneration. We test for historical observations of hardwood facilitation against the null hypothesis of competitive exclusion. Our results provide evidence of hardwood facilitation on newly germinated longleaf pine seedlings (
-
the path back oaks quercus spp facilitate longleaf pine Pinus palustris seedling establishment in xeric sites
Ecosphere, 2016Co-Authors: Louise E Loudermilk, Kevin J Hiers, Joseph J Obrien, Scott Pokswinski, Analie Barnett, Robert J. MitchellAbstract:Understanding plant-plant facilitation is critical for predicting how plant community func- tion will respond to changing disturbance and climate. In longleaf pine (Pinus palustris Mill.) ecosystems of the southeastern United States, understanding processes that affect pine reproduction is imperative for conservation efforts that aim to maintain ecosystem resilience across its wide geographic range and edaphic gradients. Variation in wildland fire and plant-plant interactions may be overlooked in "coarse filter" restoration management, where actions are often prescribed over a variety of ecological conditions with an assumed outcome. For example, hardwood reduction techniques are commonly deemed neces- sary for ecological restoration of longleaf pine ecosystems, as hardwoods are presumed competitors with longleaf pine seedlings. Natural regeneration dynamics are difficult to test experimentally given the in- frequent and irregular mast seed events of the longleaf pine. Using a long- term, large- scale restoration ex- periment and a long- term monitoring data site at Eglin Air Force Base, Florida (USA), this study explores the influence of native fire- intolerant oaks on longleaf regeneration. We test for historical observations of hardwood facilitation against the null hypothesis of competitive exclusion. Our results provide evidence of hardwood facilitation on newly germinated longleaf pine seedlings (<2 yr old) after two mast seeding events (1996, 2011). Using regression- tree and Kaplan-Meier survival analyses, we found that deciduous oak midstory density was the most significant variable associated with longleaf pine seedling survival rates in the first 2 yr after germination. We found that as few as 43 oak midstory stems ha −1 were sufficient to facilitate seedling survival, but as many as 1400 stems ha −1 maintained facilitation without competitive exclusion of seedlings. We found that 1.5- yr- old pine seedlings were more moisture stressed under more open canopy conditions when compared to those immediately adjacent to a midstory oak canopy. Rec- ognition that deciduous oaks are important facilitators of longleaf seedling establishment on xeric sites represents a significant departure from conventional wisdom and current management practices that has largely focused on competitive exclusion. This points to a critical role of a deciduous oak midstory of moderate densities for long- term ecosystem resilience in xeric longleaf pine ecosystems in light of climate uncertainty.
-
Longleaf pine (Pinus palustris) and hardwood dynamics in a fire-maintained ecosystem: A simulation approach
Ecological Modelling, 2011Co-Authors: E. Louise Loudermilk, Robert J. Mitchell, Wendell P. Cropper, H. LeeAbstract:a b s t r a c t Longleaf pine (Pinus palustris) savannas of the southeastern U.S. represent an archetype of a fire depen- dent ecosystem. They are known to have very short fire return intervals (∼1-3 years) that perpetuate understory plant diversity (up to 50 species m−2), support pine recruitment, and suppress fire sensitive hardwoods. Understanding the relationships that regulate longleaf and southern hardwoods is espe- cially critical. With decreased fire frequency, insufficient intensity, or lack of underground competition, a woody mid-story rapidly develops, dominated by fire sensitive trees and shrubs that in-turn suppress more fire dependent species (including pine seedlings). This may occur in forest gaps, where pine-needle abundance is diminished, reducing fire spread potential. The interactions between longleaf pine, hard- woods, forest fuels, and fire frequency are complex and difficult to understand spatially. The objective of this study was to develop a spatially explicit longleaf pine-hardwood stochastic simulation model (LLM), incorporating tree demography, plant competition, and fuel and fire characteristics. Data from two longleaf pine study sites were used to develop and evaluate the model with the goal to incorporate simple site-specific calibration parameters for model versatility. Specific model components included pine seed masting, hardwood clonal sprouting, response to fire (re-sprouting, mortality), and tree den-
-
forest floor depth mediates understory vigor in xeric Pinus palustris ecosystems
Ecological Applications, 2007Co-Authors: Kevin J Hiers, Joseph J Obrien, Rodney E Will, Robert J. MitchellAbstract:Longleaf pine (Pinus palustris) woodlands and savannas are among the most frequently burned ecosystems in the world with fire return intervals of 1–10 years. This fire regime has maintained high levels of biodiversity in terms of both species richness and endemism. Land use changes have reduced the area of this ecosystem by >95%, and inadequate fire frequencies threaten many of the remnants today. In the absence of frequent fire, rapid colonization of hardwoods and shrubs occurs, and a broad-leaved midstory develops. This midstory encroachment has been the focus of much research and management concern, largely based on the assumption that the midstory reduces understory plant diversity through direction competition via light interception. The general application of this mechanism of degradation is questionable, however, because midstory density, leaf area, and hardwood species composition vary substantially along a soil moisture gradient from mesic to extremely xeric sites. Reanalysis of recently reported...
-
forest floor depth mediates understory vigor in xeric Pinus palustris ecosystems
Ecological Applications, 2007Co-Authors: Kevin J Hiers, Joseph J Obrien, Rodney E Will, Robert J. MitchellAbstract:Longleaf pine (Pinus palustris) woodlands and savannas are among the most frequently burned ecosystems in the world with fire return intervals of 1-10 years. This fire regime has maintained high levels of biodiversity in terms of both species richness and endemism. Land use changes have reduced the area of this ecosystem by >95%, and inadequate fire frequencies threaten many of the remnants today. In the absence of frequent fire, rapid colonization of hardwoods and shrubs occurs, and a broad-leaved midstory develops. This midstory encroachment has been the focus of much research and management concern, largely based on the assumption that the midstory reduces understory plant diversity through direction competition via light interception. The general application of this mechanism of degradation is questionable, however, because midstory density, leaf area, and hardwood species composition vary substantially along a soil moisture gradient from mesic to extremely xeric sites. Reanalysis of recently reported data from xeric longleaf pine communities suggests that the development of the forest floor, a less conspicuous change in forest structure, might cause a decline in plant biodiversity when forests remain unburned. We report here a test of the interactions among fire, litter accumulation, forest floor development, and midstory canopy density on understory plant diversity. Structural equation modeling showed that within xeric sites, forest floor development was the primary factor explaining decreased biodiversity. The only effects of midstory development on biodiversity were those mediated through forest floor development. Boundary line analysis of functional guilds of understory plants showed sensitivity to even minor development of the forest floor in the absence of fire. These results challenge the prevailing management paradigm and suggest that within xeric longleaf pine communities, the primary focus of managed fire regime should be directed toward the restoration of forest floor characteristics rather than the introduction of high-intensity fires used to regulate midstory structure.
Peter T. Soulé - One of the best experts on this subject based on the ideXlab platform.
-
A comparison of the climate response of longleaf pine (Pinus palustris Mill.) trees among standardized measures of earlywood, latewood, adjusted latewood, and totalwood radial growth
Trees, 2021Co-Authors: Peter T. Soulé, Paul A. Knapp, Justin T. Maxwell, Tyler J. MitchellAbstract:Key message Longleaf pine radial growth is primarily driven by late summer moisture availability, latewood and adjusted latewood are more sensitive to climate than either earlywood or totalwood, and there is a high level of agreement spatially in growth/climate responses. Abstract Our objective was to examine broadly the climate–growth responses of longleaf pine ( Pinus palustris Mill.) on the Coastal Plain province of North and South Carolina to temperature, precipitation, and drought severity. We compared the responses between standardized earlywood, latewood, adjusted latewood, and totalwood radial tree growth. We sampled mature longleaf pine growing in open-canopy savanna environments and developed six tree-ring chronologies using standard dendroecological techniques. We used a combination of Pearson correlation, moving interval correlation, and Fisher r – z tests to determine which monthly and seasonal variables were most closely related to radial growth, the temporal stability of the dominant growth/climate relationship, and whether earlywood and latewood growth provide significantly different climate responses. Our results show that the strongest relationships with climate are with adjusted latewood growth and that rainfall in the later parts of the growing season (i.e., July–September) is the primary control of radial growth. Spatially, we found that growth/climate responses were similar throughout the Coastal Plain region encompassing the six study sites. Temporally, we found that July–September precipitation produced significant ( p
-
A comparison of the climate response of longleaf pine ( Pinus palustris Mill.) trees among standardized measures of earlywood, latewood, adjusted latewood, and totalwood radial growth
Trees, 2021Co-Authors: Peter T. Soulé, Paul A. Knapp, Justin T. Maxwell, Tyler J. MitchellAbstract:Longleaf pine radial growth is primarily driven by late summer moisture availability, latewood and adjusted latewood are more sensitive to climate than either earlywood or totalwood, and there is a high level of agreement spatially in growth/climate responses. Our objective was to examine broadly the climate–growth responses of longleaf pine (Pinus palustris Mill.) on the Coastal Plain province of North and South Carolina to temperature, precipitation, and drought severity. We compared the responses between standardized earlywood, latewood, adjusted latewood, and totalwood radial tree growth. We sampled mature longleaf pine growing in open-canopy savanna environments and developed six tree-ring chronologies using standard dendroecological techniques. We used a combination of Pearson correlation, moving interval correlation, and Fisher r–z tests to determine which monthly and seasonal variables were most closely related to radial growth, the temporal stability of the dominant growth/climate relationship, and whether earlywood and latewood growth provide significantly different climate responses. Our results show that the strongest relationships with climate are with adjusted latewood growth and that rainfall in the later parts of the growing season (i.e., July–September) is the primary control of radial growth. Spatially, we found that growth/climate responses were similar throughout the Coastal Plain region encompassing the six study sites. Temporally, we found that July–September precipitation produced significant (p
-
Microelevational Differences Affect Longleaf Pine (Pinus palustris Mill.) Sensitivity to Tropical Cyclone Precipitation: A Case Study Using LiDAR
Tree-Ring Research, 2020Co-Authors: Evan E. Montpellier, Paul A. Knapp, Peter T. Soulé, Justin T. MaxwellAbstract:Latewood ring widths of longleaf pine (Pinus palustris Mill.) growing on Carolina bay sand rims on the coastal plains of North Carolina are effective recorders of tropical cycone precipitation (TCP). Longleaf pine are hypothesized to be effective recorders of TCP because of their extensive lateral root structure that is exposed to enhanced soil moisture when TCP events raise the water table to root level, but this hypothesis has not been empirically tested. In this study, we used a combination of North Carolina Phase 1 LiDAR and high-precision georeferenced data to investigate the relationship between radial tree growth, TCP, and microelevation. Our findings suggest that the strength of correlations between latewood ring widths and TCP are positively correlated (p < 0.05) with tree elevation on Carolina bay sand rims, resulting in greater sensistivity of trees at higher elevations. These findings suggest that in some environments, microelevational differences (
-
microelevational differences affect longleaf pine Pinus palustris mill sensitivity to tropical cyclone precipitation a case study using lidar
Tree-ring Research, 2020Co-Authors: Paul A. Knapp, Evan E. Montpellier, Peter T. Soulé, Justin T. MaxwellAbstract:Latewood ring widths of longleaf pine (Pinus palustris Mill.) growing on Carolina bay sand rims on the coastal plains of North Carolina are effective recorders of tropical cycone precipitation (TCP). Longleaf pine are hypothesized to be effective recorders of TCP because of their extensive lateral root structure that is exposed to enhanced soil moisture when TCP events raise the water table to root level, but this hypothesis has not been empirically tested. In this study, we used a combination of North Carolina Phase 1 LiDAR and high-precision georeferenced data to investigate the relationship between radial tree growth, TCP, and microelevation. Our findings suggest that the strength of correlations between latewood ring widths and TCP are positively correlated (p < 0.05) with tree elevation on Carolina bay sand rims, resulting in greater sensistivity of trees at higher elevations. These findings suggest that in some environments, microelevational differences (<1 m) may significantly affect climate/radial growth relationships and the use of high-resolution LiDAR technology may be an effective tool for better understanding the role of microtopography on radial growth patterns.
-
tropical cyclone rainfall variability in coastal north carolina derived from longleaf pine Pinus palustris mill ad 1771 2014
Climatic Change, 2016Co-Authors: Paul A. Knapp, Justin T. Maxwell, Peter T. SouléAbstract:Records of tropical cyclone precipitation (TCP) in the USA typically begin in the mid-20th century and are insufficiently long to fully understand the natural range of TCP variability. In southeastern North Carolina, USA, we use longleaf pine (Pinus palustris Mill.) latewood chronologies from two study sites and a combined chronology as a proxy for TCP during AD 1771–2014 as the latewood growth period of June 1st–October 15th coincides with 93 % of annual TCP. We correlate latewood radial growth with TCP based on days when tropical cyclones tracked within a 223 km rain field, with the results (r = 0.71, p < 0.01) supporting the viability of this species to chronicle interannual variations in TCP for multiple centuries. Using annual latewood data during 1953–2014, we reconstruct TCP back to 1836 for the combined chronology. We creat three radial-growth groups (low, near-average, high) and find that corresponding TCP values are significantly different (p < 0.05) between groups. Low radial-growth values are a strong marker (91 % occurrence) of below-average TCP years and high radial-growth years are (73 % occurrence) also good indicators of above-average TCP years. Examination of the temporal occurrence of below- and above-average TCP years into the late 18th century indicate that a predominance of below-average TCP years occur from 1815 to 1876 that are unmatched in the historic record. The high fidelity between longleaf pine latewood growth and TCP coupled with the geographic distribution of the species throughout the southeastern USA where tropical cyclones are common suggest the utility of this species to help better understand the temporal variability of precipitation delivered via tropical cyclones.
Hugo H. Rogers - One of the best experts on this subject based on the ideXlab platform.
-
calcium sulfate deposits associated with needle substomatal cavities of container grown longleaf pine Pinus palustris seedlings
International Journal of Plant Sciences, 2000Co-Authors: Seth G. Pritchard, Stephen A. Prior, Hugo H. Rogers, Curt. M. PetersonAbstract:Extracellular calcium sulfate (CaSO4) formations associated with substomatal cavities of longleaf pine (Pinus palustris Mill.) are described. Longleaf pine seedlings were grown with two levels of soil nitrogen (N) (40 or 400 kg N ha−1 yr−1) and water stress (−0.5 or −1.5 MPa xylem pressure potential) in open‐top field chambers under two levels of atmospheric CO2 (365 or 720 μmol mol−1). Needles were subjected to scanning electron microscopy after 12 mo exposure to experimental conditions. Crystalline to fibrillar formations, appressed to surfaces of guard cells facing the interior of the needle, were observed in all treatments. In some cases, both crystalline and fibrillar formations were observed to occur within the same needle cross section. Formations were characterized as calcium sulfate using energy‐dispersive spectrometry. Crystal‐like CaSO4 appeared to originate from guard cells in the vicinity of the stomatal aperture. Formations may arise from evaporation of plant water at the interface between s...
-
Calcium Sulfate Deposits Associated with Needle Substomatal Cavities of Container‐Grown Longleaf Pine (Pinus palustris) Seedlings
International Journal of Plant Sciences, 2000Co-Authors: Seth G. Pritchard, Stephen A. Prior, Hugo H. Rogers, Curt. M. PetersonAbstract:Extracellular calcium sulfate (CaSO4) formations associated with substomatal cavities of longleaf pine (Pinus palustris Mill.) are described. Longleaf pine seedlings were grown with two levels of soil nitrogen (N) (40 or 400 kg N ha−1 yr−1) and water stress (−0.5 or −1.5 MPa xylem pressure potential) in open‐top field chambers under two levels of atmospheric CO2 (365 or 720 μmol mol−1). Needles were subjected to scanning electron microscopy after 12 mo exposure to experimental conditions. Crystalline to fibrillar formations, appressed to surfaces of guard cells facing the interior of the needle, were observed in all treatments. In some cases, both crystalline and fibrillar formations were observed to occur within the same needle cross section. Formations were characterized as calcium sulfate using energy‐dispersive spectrometry. Crystal‐like CaSO4 appeared to originate from guard cells in the vicinity of the stomatal aperture. Formations may arise from evaporation of plant water at the interface between s...
-
Tissue chemistry and carbon allocation in seedlings of Pinus palustris subjected to elevated atmospheric CO2 and water stress
Tree physiology, 1999Co-Authors: G. B. Runion, Robert J. Mitchell, Stephen A. Prior, James A. Entry, Hugo H. RogersAbstract:Longleaf pine (Pinus palustris Mill.) seedlings were grown in 45-l pots and exposed to ambient or elevated (365 or 730 mmol CO(2) mol(-1)) CO(2) concentration in open-top chambers for 20 months. Two water-stress treatments (target values of -0.5 or -1.5 MPa xylem pressure potential) were imposed 19 weeks after initiation of the study. At harvest, tissues (needles, stems, taproots, coarse roots, and fine roots) were analyzed for carbon (C), nitrogen (N), nonpolar extractives (fats, waxes, and oils), nonstructural carbohydrates (sugars and starch), structural components (cellulose and lignin), and tannins. The greatest dry weights and lowest N concentrations occurred in tissues of plants grown at elevated CO(2) or with adequate water. Although allocation of C fractions among tissues was generally unaffected by treatments, concentrations of the analyzed compounds were influenced by treatments in needles and taproots, but not in stems and lateral roots. Needles and taproots of plants exposed to elevated CO(2) had increased concentrations of nonstructural carbohydrates. Among plant tissues, elevated CO(2) caused reductions in structural C concentrations and foliar concentrations of fats, waxes and oils.
-
Influence of atmospheric CO2 enrichment, soil N, and water stress on needle surface wax formation in Pinus palustris (Pinaceae)
American journal of botany, 1997Co-Authors: Stephen A. Prior, Seth G. Pritchard, Hugo H. Rogers, G. B. Runion, Robert J. MitchellAbstract:Interactive effects of increasing atmospheric CO 2 with resource limitations on production of surface wax in plants have not been studied. Pinus palustris seedlings were grown for 1 yr at two levels of soil N (40 or 400 kg N·ha 21·yr21) and water stress (-0.5 or -1.5 MPa xylem pressure potential) in open-top field chambers under two levels of CO 2 (365 or 720 mmol/ mol). Needle surface wax content was determined at 8 mo (fall) and 12 mo (spring) and epicuticular wax morphology was examined using scanning electron microscopy (SEM) at 12 mo. Wax content expressed on both a leaf area and dry mass basis was increased due to main effects of low N and water stress. No main effects of CO2 were observed; however, a CO2 3 N interaction at 12 mo indicated that under low soil N the elevated CO2 treatment had less wax (surface area or dry mass basis) compared to its ambient counterpart. Morphologically, low N needle surfaces appeared rougher compared to those of high N needles due to more extensive wax ridges. Although the main effect of water treatment on wax density was not reflected by changes in wax morphology, the CO 2 3 N interaction was paralleled by alterations in wax appearance. Decreases in density and less prominent epicuticular wax ridges resulting from growth under elevated CO2 and limiting N suggest that dynamics of plant/atmosphere and plant/pathogen interactions may be altered.
-
Elevated atmospheric CO2 differentially affects needle chloroplast ultrastructure and phloem anatomy in Pinus palustris: interactions with soil resource availability
Plant Cell and Environment, 1997Co-Authors: Seth G. Pritchard, Stephen A. Prior, C. M. Peterson, Hugo H. RogersAbstract:The response of forest species to increasing atmospheric CO2, particularly under resource limitations, will require study in order to predict probable changes which may occur at the plant, community and ecosystem levels. Longleaf pine (Pinus palustris Mill.) seedlings were grown for 20 months at two levels of CO2 (365 and 720 µ mol mol –1 ) in two levels of soil nitrogen (4 and 40 g m –2 ), and with two levels of soil moisture (–0·5 and –1·5 MPa xylem pressure potential). Leaf tissue was collected in the spring (12 months exposure) and autumn (20 months exposure) and examined using transmission electron microscopy (TEM) and light microscopy. During early spring, elevated CO2 magnified effects of N and water treatment on starch accumulation and in some cases contributed to altered organization of mesophyll chloroplasts. Disruption of chloroplast integrity was pronounced under elevated CO2, low N and water stress. In autumn, needles contained little starch; however, chloroplasts grown under high CO2 exhibited stress symp toms including increased plastoglobuli and shorter grana. A trend for reduced needle phloem cross-sectional area result ing from fewer sieve cells was also observed under elevated CO2. These results suggest that, in nature, longleaf pine seedlings may not benefit from a doubling of CO2, espe cially when soil resources are limiting.
Paul A. Knapp - One of the best experts on this subject based on the ideXlab platform.
-
A comparison of the climate response of longleaf pine ( Pinus palustris Mill.) trees among standardized measures of earlywood, latewood, adjusted latewood, and totalwood radial growth
Trees, 2021Co-Authors: Peter T. Soulé, Paul A. Knapp, Justin T. Maxwell, Tyler J. MitchellAbstract:Longleaf pine radial growth is primarily driven by late summer moisture availability, latewood and adjusted latewood are more sensitive to climate than either earlywood or totalwood, and there is a high level of agreement spatially in growth/climate responses. Our objective was to examine broadly the climate–growth responses of longleaf pine (Pinus palustris Mill.) on the Coastal Plain province of North and South Carolina to temperature, precipitation, and drought severity. We compared the responses between standardized earlywood, latewood, adjusted latewood, and totalwood radial tree growth. We sampled mature longleaf pine growing in open-canopy savanna environments and developed six tree-ring chronologies using standard dendroecological techniques. We used a combination of Pearson correlation, moving interval correlation, and Fisher r–z tests to determine which monthly and seasonal variables were most closely related to radial growth, the temporal stability of the dominant growth/climate relationship, and whether earlywood and latewood growth provide significantly different climate responses. Our results show that the strongest relationships with climate are with adjusted latewood growth and that rainfall in the later parts of the growing season (i.e., July–September) is the primary control of radial growth. Spatially, we found that growth/climate responses were similar throughout the Coastal Plain region encompassing the six study sites. Temporally, we found that July–September precipitation produced significant (p
-
A comparison of the climate response of longleaf pine (Pinus palustris Mill.) trees among standardized measures of earlywood, latewood, adjusted latewood, and totalwood radial growth
Trees, 2021Co-Authors: Peter T. Soulé, Paul A. Knapp, Justin T. Maxwell, Tyler J. MitchellAbstract:Key message Longleaf pine radial growth is primarily driven by late summer moisture availability, latewood and adjusted latewood are more sensitive to climate than either earlywood or totalwood, and there is a high level of agreement spatially in growth/climate responses. Abstract Our objective was to examine broadly the climate–growth responses of longleaf pine ( Pinus palustris Mill.) on the Coastal Plain province of North and South Carolina to temperature, precipitation, and drought severity. We compared the responses between standardized earlywood, latewood, adjusted latewood, and totalwood radial tree growth. We sampled mature longleaf pine growing in open-canopy savanna environments and developed six tree-ring chronologies using standard dendroecological techniques. We used a combination of Pearson correlation, moving interval correlation, and Fisher r – z tests to determine which monthly and seasonal variables were most closely related to radial growth, the temporal stability of the dominant growth/climate relationship, and whether earlywood and latewood growth provide significantly different climate responses. Our results show that the strongest relationships with climate are with adjusted latewood growth and that rainfall in the later parts of the growing season (i.e., July–September) is the primary control of radial growth. Spatially, we found that growth/climate responses were similar throughout the Coastal Plain region encompassing the six study sites. Temporally, we found that July–September precipitation produced significant ( p
-
Microelevational Differences Affect Longleaf Pine (Pinus palustris Mill.) Sensitivity to Tropical Cyclone Precipitation: A Case Study Using LiDAR
Tree-Ring Research, 2020Co-Authors: Evan E. Montpellier, Paul A. Knapp, Peter T. Soulé, Justin T. MaxwellAbstract:Latewood ring widths of longleaf pine (Pinus palustris Mill.) growing on Carolina bay sand rims on the coastal plains of North Carolina are effective recorders of tropical cycone precipitation (TCP). Longleaf pine are hypothesized to be effective recorders of TCP because of their extensive lateral root structure that is exposed to enhanced soil moisture when TCP events raise the water table to root level, but this hypothesis has not been empirically tested. In this study, we used a combination of North Carolina Phase 1 LiDAR and high-precision georeferenced data to investigate the relationship between radial tree growth, TCP, and microelevation. Our findings suggest that the strength of correlations between latewood ring widths and TCP are positively correlated (p < 0.05) with tree elevation on Carolina bay sand rims, resulting in greater sensistivity of trees at higher elevations. These findings suggest that in some environments, microelevational differences (
-
microelevational differences affect longleaf pine Pinus palustris mill sensitivity to tropical cyclone precipitation a case study using lidar
Tree-ring Research, 2020Co-Authors: Paul A. Knapp, Evan E. Montpellier, Peter T. Soulé, Justin T. MaxwellAbstract:Latewood ring widths of longleaf pine (Pinus palustris Mill.) growing on Carolina bay sand rims on the coastal plains of North Carolina are effective recorders of tropical cycone precipitation (TCP). Longleaf pine are hypothesized to be effective recorders of TCP because of their extensive lateral root structure that is exposed to enhanced soil moisture when TCP events raise the water table to root level, but this hypothesis has not been empirically tested. In this study, we used a combination of North Carolina Phase 1 LiDAR and high-precision georeferenced data to investigate the relationship between radial tree growth, TCP, and microelevation. Our findings suggest that the strength of correlations between latewood ring widths and TCP are positively correlated (p < 0.05) with tree elevation on Carolina bay sand rims, resulting in greater sensistivity of trees at higher elevations. These findings suggest that in some environments, microelevational differences (<1 m) may significantly affect climate/radial growth relationships and the use of high-resolution LiDAR technology may be an effective tool for better understanding the role of microtopography on radial growth patterns.
-
Comparison of climate–growth responses of montane and piedmont longleaf pine ( Pinus palustris Mill.) chronologies in North Carolina
Trees, 2019Co-Authors: Tyler J. Mitchell, Thomas Patterson, Paul A. KnappAbstract:Montane longleaf pine tree-ring chronologies exhibit fidelity to summer soil-moisture conditions. Multi-century climate reconstructions using longleaf pine can provide insights into the natural range of moisture variability. Longleaf pine (Pinus palustris Mill.) ring width is associated with temperature and precipitation throughout its range, yet intrasite comparisons of climate and ring growth are limited and have not examined interior (i.e., montane vs. piedmont) populations. Here, we investigated remnant stands of montane and piedmont longleaf pine in central North Carolina and compared their sensitivity to summer climatic variables during 1935–2015. Summer precipitation and PDSI were better associated with tree-ring chronologies developed from latewood growth from both the montane (r = 0.429 PDSI, r = 0.563 precipitation) and piedmont (r = 0.252, r = 0.441) chronologies while correlations with temperature variables were either weak (r = − 0.249 maximum temperature montane, r = − 0.229 piedmont) or not significant. We examined longleaf pine latewood sensitivity to late-summer (July–September) climate conditions, drought detection, and differences in radial growth during drought and non-drought periods and found greater sensitivity of the montane chronology to these metrics. Specifically, the montane chronology was more sensitive to drought detection identifying all 11 droughts that occurred during the 81-year study period, while the piedmont chronology identified only 6 of the 11. Further, while significant differences in radial growth existed between drought and non-drought years for both chronologies, the montane chronology exhibited considerably greater growth range between these favorable and unfavorable periods. These results indicate the use of montane longleaf pine is preferable when reconstructing precipitation variability and when coupled with remnant stump data provide an opportunity to reconstruct summer climate variability.
Stephen A. Prior - One of the best experts on this subject based on the ideXlab platform.
-
calcium sulfate deposits associated with needle substomatal cavities of container grown longleaf pine Pinus palustris seedlings
International Journal of Plant Sciences, 2000Co-Authors: Seth G. Pritchard, Stephen A. Prior, Hugo H. Rogers, Curt. M. PetersonAbstract:Extracellular calcium sulfate (CaSO4) formations associated with substomatal cavities of longleaf pine (Pinus palustris Mill.) are described. Longleaf pine seedlings were grown with two levels of soil nitrogen (N) (40 or 400 kg N ha−1 yr−1) and water stress (−0.5 or −1.5 MPa xylem pressure potential) in open‐top field chambers under two levels of atmospheric CO2 (365 or 720 μmol mol−1). Needles were subjected to scanning electron microscopy after 12 mo exposure to experimental conditions. Crystalline to fibrillar formations, appressed to surfaces of guard cells facing the interior of the needle, were observed in all treatments. In some cases, both crystalline and fibrillar formations were observed to occur within the same needle cross section. Formations were characterized as calcium sulfate using energy‐dispersive spectrometry. Crystal‐like CaSO4 appeared to originate from guard cells in the vicinity of the stomatal aperture. Formations may arise from evaporation of plant water at the interface between s...
-
Calcium Sulfate Deposits Associated with Needle Substomatal Cavities of Container‐Grown Longleaf Pine (Pinus palustris) Seedlings
International Journal of Plant Sciences, 2000Co-Authors: Seth G. Pritchard, Stephen A. Prior, Hugo H. Rogers, Curt. M. PetersonAbstract:Extracellular calcium sulfate (CaSO4) formations associated with substomatal cavities of longleaf pine (Pinus palustris Mill.) are described. Longleaf pine seedlings were grown with two levels of soil nitrogen (N) (40 or 400 kg N ha−1 yr−1) and water stress (−0.5 or −1.5 MPa xylem pressure potential) in open‐top field chambers under two levels of atmospheric CO2 (365 or 720 μmol mol−1). Needles were subjected to scanning electron microscopy after 12 mo exposure to experimental conditions. Crystalline to fibrillar formations, appressed to surfaces of guard cells facing the interior of the needle, were observed in all treatments. In some cases, both crystalline and fibrillar formations were observed to occur within the same needle cross section. Formations were characterized as calcium sulfate using energy‐dispersive spectrometry. Crystal‐like CaSO4 appeared to originate from guard cells in the vicinity of the stomatal aperture. Formations may arise from evaporation of plant water at the interface between s...
-
Tissue chemistry and carbon allocation in seedlings of Pinus palustris subjected to elevated atmospheric CO2 and water stress
Tree physiology, 1999Co-Authors: G. B. Runion, Robert J. Mitchell, Stephen A. Prior, James A. Entry, Hugo H. RogersAbstract:Longleaf pine (Pinus palustris Mill.) seedlings were grown in 45-l pots and exposed to ambient or elevated (365 or 730 mmol CO(2) mol(-1)) CO(2) concentration in open-top chambers for 20 months. Two water-stress treatments (target values of -0.5 or -1.5 MPa xylem pressure potential) were imposed 19 weeks after initiation of the study. At harvest, tissues (needles, stems, taproots, coarse roots, and fine roots) were analyzed for carbon (C), nitrogen (N), nonpolar extractives (fats, waxes, and oils), nonstructural carbohydrates (sugars and starch), structural components (cellulose and lignin), and tannins. The greatest dry weights and lowest N concentrations occurred in tissues of plants grown at elevated CO(2) or with adequate water. Although allocation of C fractions among tissues was generally unaffected by treatments, concentrations of the analyzed compounds were influenced by treatments in needles and taproots, but not in stems and lateral roots. Needles and taproots of plants exposed to elevated CO(2) had increased concentrations of nonstructural carbohydrates. Among plant tissues, elevated CO(2) caused reductions in structural C concentrations and foliar concentrations of fats, waxes and oils.
-
Influence of atmospheric CO2 enrichment, soil N, and water stress on needle surface wax formation in Pinus palustris (Pinaceae)
American journal of botany, 1997Co-Authors: Stephen A. Prior, Seth G. Pritchard, Hugo H. Rogers, G. B. Runion, Robert J. MitchellAbstract:Interactive effects of increasing atmospheric CO 2 with resource limitations on production of surface wax in plants have not been studied. Pinus palustris seedlings were grown for 1 yr at two levels of soil N (40 or 400 kg N·ha 21·yr21) and water stress (-0.5 or -1.5 MPa xylem pressure potential) in open-top field chambers under two levels of CO 2 (365 or 720 mmol/ mol). Needle surface wax content was determined at 8 mo (fall) and 12 mo (spring) and epicuticular wax morphology was examined using scanning electron microscopy (SEM) at 12 mo. Wax content expressed on both a leaf area and dry mass basis was increased due to main effects of low N and water stress. No main effects of CO2 were observed; however, a CO2 3 N interaction at 12 mo indicated that under low soil N the elevated CO2 treatment had less wax (surface area or dry mass basis) compared to its ambient counterpart. Morphologically, low N needle surfaces appeared rougher compared to those of high N needles due to more extensive wax ridges. Although the main effect of water treatment on wax density was not reflected by changes in wax morphology, the CO 2 3 N interaction was paralleled by alterations in wax appearance. Decreases in density and less prominent epicuticular wax ridges resulting from growth under elevated CO2 and limiting N suggest that dynamics of plant/atmosphere and plant/pathogen interactions may be altered.
-
Elevated atmospheric CO2 differentially affects needle chloroplast ultrastructure and phloem anatomy in Pinus palustris: interactions with soil resource availability
Plant Cell and Environment, 1997Co-Authors: Seth G. Pritchard, Stephen A. Prior, C. M. Peterson, Hugo H. RogersAbstract:The response of forest species to increasing atmospheric CO2, particularly under resource limitations, will require study in order to predict probable changes which may occur at the plant, community and ecosystem levels. Longleaf pine (Pinus palustris Mill.) seedlings were grown for 20 months at two levels of CO2 (365 and 720 µ mol mol –1 ) in two levels of soil nitrogen (4 and 40 g m –2 ), and with two levels of soil moisture (–0·5 and –1·5 MPa xylem pressure potential). Leaf tissue was collected in the spring (12 months exposure) and autumn (20 months exposure) and examined using transmission electron microscopy (TEM) and light microscopy. During early spring, elevated CO2 magnified effects of N and water treatment on starch accumulation and in some cases contributed to altered organization of mesophyll chloroplasts. Disruption of chloroplast integrity was pronounced under elevated CO2, low N and water stress. In autumn, needles contained little starch; however, chloroplasts grown under high CO2 exhibited stress symp toms including increased plastoglobuli and shorter grana. A trend for reduced needle phloem cross-sectional area result ing from fewer sieve cells was also observed under elevated CO2. These results suggest that, in nature, longleaf pine seedlings may not benefit from a doubling of CO2, espe cially when soil resources are limiting.