Ecological applications : a publication of the Ecological Society of America, Jan 21, 2016
Balancing economic, ecological and social values has long been a challenge in the forests of the ... more Balancing economic, ecological and social values has long been a challenge in the forests of the Pacific Northwest, where conflict over timber harvest and old-growth habitat on public lands has been contentious for the past several decades. The Northwest Forest Plan, adopted two decades ago to guide management on federal lands, is currently being revised as the region searches for a balance between sustainable timber yields and habitat for sensitive species. In addition, climate change imposes a high degree of uncertainty on future forest productivity, sustainability of timber harvest, wildfire risk, and species habitat. We evaluated the long-term, landscape-scale tradeoffs among carbon (C) storage, timber yield, and old forest habitat given projected climate change and shifts in forest management policy across 2.1 million hectares of forests in the Oregon Coast Range. Projections highlight the divergence between private and public lands under business-as-usual forest management, wh...
Bulletin of The Ecological Society of America, 1995
This study tests the potential for interactions between root-zone temperature and COâ for plants ... more This study tests the potential for interactions between root-zone temperature and COâ for plants which co-occur in a habitat where root-zone temperature fluctuate throughout the day. Controlled environment studies were conducted to expose desert plants to combinations of low or high root zone temperatures and low or high COâ. Artemisia tridentata, Sitanion hystrix, and Stipa thurberiana were chosen for study
Background/Question/Methods The complex interactions among disturbances under a changing climate ... more Background/Question/Methods The complex interactions among disturbances under a changing climate are difficult to disentangle, especially given their dynamic nature. To improve our understanding of how windstorms and climate change may affect carbon cycling, we are using a forest landscape disturbance and succession model (LANDIS-II, Century extension) to project carbon sequestration in northern Minnesota under multiple climate change and disturbance scenarios. The model was calibrated and validated using empirical estimates of aboveground productivity (ANPP) and net ecosystem exchange. Results/Conclusions Our preliminary simulations suggest that climate change will have a much greater impact on C sequestration than windstorms. Climate change lowered C sequestration by 20%, whereas wind reduced sink strength by only 13%. Under the GFDL A1FI climate scenario, windstorms initially lowered C sequestration but by year 2050, wind actually increased C sequestration through higher ANPP. Ou...
Background/Question/Methods Forests are a major component of the global carbon cycle, and scienti... more Background/Question/Methods Forests are a major component of the global carbon cycle, and scientists and managers are exploring the use of forest management options for climate change mitigation. In the highly productive forests of the Oregon Coast Range, climate change mitigation could take the form of different management strategies, including restricting harvest to maximize ecosystem carbon sequestration, or removing forest residue along with harvesting as a source of renewable woody biomass energy. However, the long-term consequences of bioenergy harvesting are unknown, particularly as Coast Range forests face novel conditions resulting from climate change. We used the LANDIS-II forest simulation model to project the impacts of climate change and management actions on above- and below-ground carbon and nitrogen dynamics in a small watershed in the northeastern Oregon Coast Range. We explored scenarios varying in future climatic conditions (including current climate and six scena...
Forests provide important ecological, economic, and social services, and recent interest has emer... more Forests provide important ecological, economic, and social services, and recent interest has emerged in the potential for using residue from timber harvest as a source of renewable woody bioenergy. The long-term consequences of such intensive harvest are unclear, particularly as forests face novel climatic conditions over the next century. We used a simulation model to project the long-term effects of management and climate change on above-and belowground forest carbon storage in a watershed in northwestern Oregon. The multi-ownership watershed has a diverse range of current management practices, including little-to-no harvesting on federal lands, short-rotation clear-cutting on industrial land, and a mix of practices on private nonindustrial land. We simulated multiple management scenarios, varying the rate and intensity of harvest, combined with projections of climate change. Our simulations project a wide range of total ecosystem carbon storage with varying harvest rate, ranging from a 45% increase to a 16% decrease in carbon compared to current levels. Increasing the intensity of harvest for bioenergy caused a 2-3% decrease in ecosystem carbon relative to conventional harvest practices. Soil carbon was relatively insensitive to harvest rotation and intensity, and accumulated slowly regardless of harvest regime. Climate change reduced carbon accumulation in soil and detrital pools due to increasing heterotrophic respiration, and had small but variable effects on aboveground live carbon and total ecosystem carbon. Overall, we conclude that current levels of ecosystem carbon storage are maintained in part due to substantial portions of the landscape (federal and some private lands) remaining unharvested or lightly managed. Increasing the intensity of harvest for bioenergy on currently harvested land, however, led to a relatively small reduction in the ability of forests to store carbon. Climate change is unlikely to substantially alter carbon storage in these forests, absent shifts in disturbance regimes.
ABSTRACT Root biomass, root production and lifespan, and root-mycorrhizal interactions govern soi... more ABSTRACT Root biomass, root production and lifespan, and root-mycorrhizal interactions govern soil carbon fluxes and resource uptake and are critical components of terrestrial models. However, limitations in data and confusions over terminology, together with a strong dependence on a small set of conceptual frameworks, have limited the exploration of root function in terrestrial models. We review the key root processes of interest to both field ecologists and modelers including root classification, production, turnover, biomass, resource uptake, and depth distribution to ask (1) what are contemporary approaches for modeling roots in terrestrial models? and (2) can these approaches be improved via recent advancements in field research methods? We isolate several emerging themes that are ready for collaboration among field scientists and modelers: (1) alternatives to size-class based root classifications based on function and the inclusion of fungal symbioses, (2) dynamic root allocation and phenology as a function of root environment, rather than leaf demand alone, (3) improved understanding of the treatment of root turnover in models, including the role of root tissue chemistry on root lifespan, (4) better estimates of root stocks across sites and species to parameterize or validate models, and (5) dynamic interplay among rooting depth, resource availability and resource uptake. Greater attention to model parameterization and structural representation of roots will lead to greater appreciation for belowground processes in terrestrial models and improve estimates of ecosystem resilience to global change drivers.
... Apatite, a ubiquitous but trace mineral in parent material, has been shown to be disproportio... more ... Apatite, a ubiquitous but trace mineral in parent material, has been shown to be disproportionately impor-tant as a source of Ca and P in young soils, because of its high weathering rate Melissa S. Lucash Dep. of Environmental Science and Management Portland State Univ. ...
Nutrient uptake by roots of mature trees is difficult to measure accurately under field condition... more Nutrient uptake by roots of mature trees is difficult to measure accurately under field conditions using existing methods. In this review, we discuss current techniques for measuring uptake at the root surface including excised roots, isotopic tracers, autoradiography, depletion, and lysimeters. Although these methods have provided many insights, each has drawbacks. Estimates of uptake are affected by the sampling scheme, experimental conditions, whether roots are excised or not, concentrations of ions, and the rate of efflux of ions. Microbes and mycorrhizas can also affect estimates of uptake. A greater focus on methods development is critical to advancing our understanding of nutrient uptake of mature trees under conditions representative of those in the field.
Nutrient uptake is generally thought to exhibit a simple seasonal pattern, but few studies have m... more Nutrient uptake is generally thought to exhibit a simple seasonal pattern, but few studies have measured temporal variation of nutrient uptake capacity in mature trees. We measured net uptake capacity of K, NH þ 4 , NO À 3 , Mg and Ca across a range of solution concentrations by roots of mature loblolly pine at Calhoun Experimental
Global climatic change as expressed by increased CO 2 and temperature has the potential for drama... more Global climatic change as expressed by increased CO 2 and temperature has the potential for dramatic effects on trees. To determine what its effects may be on Pacific Northwest forests, Douglas-fir (Pseudotsuga menziesii ) seedlings were grown in sun-lit controlled environment chambers at ambient or elevated (+ 4°C above ambient) temperature, and at ambient or elevated ( +200 ppm above ambient) CO 2 . elevated CO 2 had no effect on vegetative bud morphology, while the following unusual morphological characteristics were found with greater frequency at elevated temperature than at ambient: rosetted buds with reflexed and loosened outer scales, convoluted inner scales, clusters of small buds, needles elongating between scales, needle primordia with white, hyaline apical extensions, and buds with hardened scales inside of unbroken buds. Buds became rosetted in elevated temperature chambers after temperatures exceeded 40°C in July, 1996. Rosettes were induced within 48-h in buds placed in a 40°C oven; fewer rosettes formed at 20°C. Induction was reversible in buds transferred from 40 to 20°C, implying that rosetting is a physical rather than a growth phenomenon. It appears that rosettes form after long-term exposure to elevated temperature and after shorter periods of exposure to intense heat. Elevated temperature influences bud morphology and may therefore influence the overall branching structure of Douglas-fir seedlings.
Ecological applications : a publication of the Ecological Society of America, Jan 21, 2016
Balancing economic, ecological and social values has long been a challenge in the forests of the ... more Balancing economic, ecological and social values has long been a challenge in the forests of the Pacific Northwest, where conflict over timber harvest and old-growth habitat on public lands has been contentious for the past several decades. The Northwest Forest Plan, adopted two decades ago to guide management on federal lands, is currently being revised as the region searches for a balance between sustainable timber yields and habitat for sensitive species. In addition, climate change imposes a high degree of uncertainty on future forest productivity, sustainability of timber harvest, wildfire risk, and species habitat. We evaluated the long-term, landscape-scale tradeoffs among carbon (C) storage, timber yield, and old forest habitat given projected climate change and shifts in forest management policy across 2.1 million hectares of forests in the Oregon Coast Range. Projections highlight the divergence between private and public lands under business-as-usual forest management, wh...
Bulletin of The Ecological Society of America, 1995
This study tests the potential for interactions between root-zone temperature and COâ for plants ... more This study tests the potential for interactions between root-zone temperature and COâ for plants which co-occur in a habitat where root-zone temperature fluctuate throughout the day. Controlled environment studies were conducted to expose desert plants to combinations of low or high root zone temperatures and low or high COâ. Artemisia tridentata, Sitanion hystrix, and Stipa thurberiana were chosen for study
Background/Question/Methods The complex interactions among disturbances under a changing climate ... more Background/Question/Methods The complex interactions among disturbances under a changing climate are difficult to disentangle, especially given their dynamic nature. To improve our understanding of how windstorms and climate change may affect carbon cycling, we are using a forest landscape disturbance and succession model (LANDIS-II, Century extension) to project carbon sequestration in northern Minnesota under multiple climate change and disturbance scenarios. The model was calibrated and validated using empirical estimates of aboveground productivity (ANPP) and net ecosystem exchange. Results/Conclusions Our preliminary simulations suggest that climate change will have a much greater impact on C sequestration than windstorms. Climate change lowered C sequestration by 20%, whereas wind reduced sink strength by only 13%. Under the GFDL A1FI climate scenario, windstorms initially lowered C sequestration but by year 2050, wind actually increased C sequestration through higher ANPP. Ou...
Background/Question/Methods Forests are a major component of the global carbon cycle, and scienti... more Background/Question/Methods Forests are a major component of the global carbon cycle, and scientists and managers are exploring the use of forest management options for climate change mitigation. In the highly productive forests of the Oregon Coast Range, climate change mitigation could take the form of different management strategies, including restricting harvest to maximize ecosystem carbon sequestration, or removing forest residue along with harvesting as a source of renewable woody biomass energy. However, the long-term consequences of bioenergy harvesting are unknown, particularly as Coast Range forests face novel conditions resulting from climate change. We used the LANDIS-II forest simulation model to project the impacts of climate change and management actions on above- and below-ground carbon and nitrogen dynamics in a small watershed in the northeastern Oregon Coast Range. We explored scenarios varying in future climatic conditions (including current climate and six scena...
Forests provide important ecological, economic, and social services, and recent interest has emer... more Forests provide important ecological, economic, and social services, and recent interest has emerged in the potential for using residue from timber harvest as a source of renewable woody bioenergy. The long-term consequences of such intensive harvest are unclear, particularly as forests face novel climatic conditions over the next century. We used a simulation model to project the long-term effects of management and climate change on above-and belowground forest carbon storage in a watershed in northwestern Oregon. The multi-ownership watershed has a diverse range of current management practices, including little-to-no harvesting on federal lands, short-rotation clear-cutting on industrial land, and a mix of practices on private nonindustrial land. We simulated multiple management scenarios, varying the rate and intensity of harvest, combined with projections of climate change. Our simulations project a wide range of total ecosystem carbon storage with varying harvest rate, ranging from a 45% increase to a 16% decrease in carbon compared to current levels. Increasing the intensity of harvest for bioenergy caused a 2-3% decrease in ecosystem carbon relative to conventional harvest practices. Soil carbon was relatively insensitive to harvest rotation and intensity, and accumulated slowly regardless of harvest regime. Climate change reduced carbon accumulation in soil and detrital pools due to increasing heterotrophic respiration, and had small but variable effects on aboveground live carbon and total ecosystem carbon. Overall, we conclude that current levels of ecosystem carbon storage are maintained in part due to substantial portions of the landscape (federal and some private lands) remaining unharvested or lightly managed. Increasing the intensity of harvest for bioenergy on currently harvested land, however, led to a relatively small reduction in the ability of forests to store carbon. Climate change is unlikely to substantially alter carbon storage in these forests, absent shifts in disturbance regimes.
ABSTRACT Root biomass, root production and lifespan, and root-mycorrhizal interactions govern soi... more ABSTRACT Root biomass, root production and lifespan, and root-mycorrhizal interactions govern soil carbon fluxes and resource uptake and are critical components of terrestrial models. However, limitations in data and confusions over terminology, together with a strong dependence on a small set of conceptual frameworks, have limited the exploration of root function in terrestrial models. We review the key root processes of interest to both field ecologists and modelers including root classification, production, turnover, biomass, resource uptake, and depth distribution to ask (1) what are contemporary approaches for modeling roots in terrestrial models? and (2) can these approaches be improved via recent advancements in field research methods? We isolate several emerging themes that are ready for collaboration among field scientists and modelers: (1) alternatives to size-class based root classifications based on function and the inclusion of fungal symbioses, (2) dynamic root allocation and phenology as a function of root environment, rather than leaf demand alone, (3) improved understanding of the treatment of root turnover in models, including the role of root tissue chemistry on root lifespan, (4) better estimates of root stocks across sites and species to parameterize or validate models, and (5) dynamic interplay among rooting depth, resource availability and resource uptake. Greater attention to model parameterization and structural representation of roots will lead to greater appreciation for belowground processes in terrestrial models and improve estimates of ecosystem resilience to global change drivers.
... Apatite, a ubiquitous but trace mineral in parent material, has been shown to be disproportio... more ... Apatite, a ubiquitous but trace mineral in parent material, has been shown to be disproportionately impor-tant as a source of Ca and P in young soils, because of its high weathering rate Melissa S. Lucash Dep. of Environmental Science and Management Portland State Univ. ...
Nutrient uptake by roots of mature trees is difficult to measure accurately under field condition... more Nutrient uptake by roots of mature trees is difficult to measure accurately under field conditions using existing methods. In this review, we discuss current techniques for measuring uptake at the root surface including excised roots, isotopic tracers, autoradiography, depletion, and lysimeters. Although these methods have provided many insights, each has drawbacks. Estimates of uptake are affected by the sampling scheme, experimental conditions, whether roots are excised or not, concentrations of ions, and the rate of efflux of ions. Microbes and mycorrhizas can also affect estimates of uptake. A greater focus on methods development is critical to advancing our understanding of nutrient uptake of mature trees under conditions representative of those in the field.
Nutrient uptake is generally thought to exhibit a simple seasonal pattern, but few studies have m... more Nutrient uptake is generally thought to exhibit a simple seasonal pattern, but few studies have measured temporal variation of nutrient uptake capacity in mature trees. We measured net uptake capacity of K, NH þ 4 , NO À 3 , Mg and Ca across a range of solution concentrations by roots of mature loblolly pine at Calhoun Experimental
Global climatic change as expressed by increased CO 2 and temperature has the potential for drama... more Global climatic change as expressed by increased CO 2 and temperature has the potential for dramatic effects on trees. To determine what its effects may be on Pacific Northwest forests, Douglas-fir (Pseudotsuga menziesii ) seedlings were grown in sun-lit controlled environment chambers at ambient or elevated (+ 4°C above ambient) temperature, and at ambient or elevated ( +200 ppm above ambient) CO 2 . elevated CO 2 had no effect on vegetative bud morphology, while the following unusual morphological characteristics were found with greater frequency at elevated temperature than at ambient: rosetted buds with reflexed and loosened outer scales, convoluted inner scales, clusters of small buds, needles elongating between scales, needle primordia with white, hyaline apical extensions, and buds with hardened scales inside of unbroken buds. Buds became rosetted in elevated temperature chambers after temperatures exceeded 40°C in July, 1996. Rosettes were induced within 48-h in buds placed in a 40°C oven; fewer rosettes formed at 20°C. Induction was reversible in buds transferred from 40 to 20°C, implying that rosetting is a physical rather than a growth phenomenon. It appears that rosettes form after long-term exposure to elevated temperature and after shorter periods of exposure to intense heat. Elevated temperature influences bud morphology and may therefore influence the overall branching structure of Douglas-fir seedlings.
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