Bernhard Splechtna - Academia.edu (original) (raw)
Papers by Bernhard Splechtna
Journal of Vegetation Science, 2005
We were interested if and how variation in frequency and/or size of disturbances affect the dynam... more We were interested if and how variation in frequency and/or size of disturbances affect the dynamics of a montane old-growth forest in Central Europe. Location: The forest, co-dominated by Fagus sylvatica, Picea abies and Abies alba, is located in Lower Austria and represents one of the few sizable virgin forests in Central Europe. Methods: We extracted cores from 100 trees using systematic grid sampling (grid cell size 10 m × 10 m) on each of four 1-ha plots distributed across the old-growth remnant of 300 ha. We inferred disturbance events from rapid early growth and release events. For defining release criteria, we applied the boundary line method. We investigated the spatial structure of current age and gap distributions and past disturbance events in grid cells, using a pair density statistic. Results: The disturbance histories indicate decades with peaks and also extended periods without disturbance. Some peaks occurred synchronously at three of the four plots (1910s, 1930s, 1960s and 1980s). Peaks and gaps in the disturbance chronologies widely agreed with peaks and gaps in the age distributions. Most disturbance events during single decades showed a random spatial distribution. Conclusions: There is considerable variation in disturbance frequency and/or severity over time. Most disturbance events will rather thin the stand than clear larger areas at once. Following scattered disturbance two pathways occur: (1) gap expansion leading to creation of larger gaps, and (2) gap closure by lateral encroachment or by subcanopy trees growing into the canopy.
Geoderma, Jul 1, 2001
concentrations appeared to be unrelated to changes in continentality within the study area. These... more concentrations appeared to be unrelated to changes in continentality within the study area. These findings agree with the results of previous studies suggesting that mineralizable-N of the mineral soil is the best property for a quantitative characterization of a soil nutrient gradient, and, hence for quantification of field-estimated SNRs. Field-estimated SNRs were also good predictors of site index as they explained the variation in site index of Pacific silver fir similarly well as total N and CrN ratio. However, the absence of a relationship between mineralizable-N and the Pacific silver fir site index requires a further study of plant-soil relationships in the area.
We present a critical review of current trends in research of spatio-temporal development of fore... more We present a critical review of current trends in research of spatio-temporal development of forests. The paper addresses (1) field methods for the development of spatially-explicit models of forest dynamics and their integration in models of forest dynamics, (2) strengths and limitations of traditional patch models versus spatiallyexplicit, individual-based models, and (3) the potential for moment-based methods in the analysis of forest dynamics. These topics are discussed with reference to their potential for solving open questions in the studies of forest dynamics. The study of spatio-temporal processes provides a link between pattern and process in plant communities, and plays a crucial role in understanding ecosystem dynamics. In the last decade, the development of spatially-explicit, individual-based models shifted the focus of forest dynamics modelling from the dynamics of discrete patches to the interactions among individual organisms, thus encapsulating the theory of ''neighbourhood'' dynamics. In turn, the stochastic properties and the complexity of spatially-explicit, individual-based models gave rise to the development of a new suite of so-called moment-based models. These new models describe the dynamics of individuals and of pairs of individuals in terms of their densities, thus directly capturing second-order information on spatial structure. So far, this approach has not been applied to forests; we indicate extensions needed for such applications. Moment-based models may be an important complement to spatially explicit individual-based models in developing a general spatial theory of forest dynamics. However, both kinds of models currently focus on fine scales, whereas a critical issue in forest dynamics is to understand the interaction of fine-scale processes with coarser-scale disturbances. To obtain a more complete picture of forest dynamics, the relevant links and interactions between fine-, intermediate-, and coarse-scale processes ought to be identified. Intensive links between modelling work and field studies designed across different scales are a promising means to create a new perspective on forest dynamics.
Height growth and site index models for Pacific silver fir in southwestern British Columbia Heigh... more Height growth and site index models for Pacific silver fir in southwestern British Columbia Height growth and site index models for Pacific silver fir in southwestern British Columbia Following an exploratory examination of the variation in the height growth pattern using a single-valued ratio, conventional polymorphic and climate-specific height growth and site index models were developed for Pacific silver fir (Abies amabilis [Dougl. ex Loud.] Forbes). The models were developed from stem analysis data obtained from 67 study plots, which were located over the entire elevation-continentality range of the species in southern coastal British Columbia. When tested against an independent data set consisting of 31 plots, the climate-specific models improved height and site index prediction compared to the conventional polymorphic models. The previ-ously available model for Pacific silver fir was biased. It overestimated height before, and underes-timated it beyond, the index age. It also...
This study examines the influence of climate on tree-ring properties of several major tree specie... more This study examines the influence of climate on tree-ring properties of several major tree species: Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and lodgepole pine (Pinus contorta var. latifolia Dougl. ex Loud.). Our three objectives were to determine how (1) tree-ring properties change along an elevation gradient, (2) short-term climatic influences are correlated with tree-ring properties, and (3) long-term climatic influence on tree-ring properties.Forestry, Faculty ofForest Sciences, Department ofReviewedFacult
Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species ... more Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in coastal forests of B.C. Its range extends from sea-level to almost timberline, and from the hypermaritime region on the west coast of Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. With this relatively wide climatic amplitude, a large variability in the height growth pattern of Pacific silver fir can be expected, since climate is considered to be the most influential determinant of the trajectory of height over age of forest trees. This variability, however, is not reflected in the height growth curves and site index tables used to estimate Pacific silver fir site index, since the curves and tables were developed from low-elevation stands on Vancouver Island. Consequently, when these curves and tables are applied to high-elevation or submaritime stands, we get biased estimates of site index. Accurate estimates of site index are necessary for ...
Site classification in the biogeoclimatic ecosystem classification system is based on three diffe... more Site classification in the biogeoclimatic ecosystem classification system is based on three differentiating properties: climatic regimes (expressed by biogeoclimatic subzones or variants), soil moisture regimes (SMRs), and soil nutrient regimes (SNRs). A SNR represents a segment of a regional soil nutrient gradient, i.e., soils which provide similar levels of plant-available nutrients over a long period. SNRs are identified in the field using a number of easily observable soil morphological properties and indicator plant species. However, we need to know to what extent soil nutrient properties support these indirect field-estimates. There have been several studies that quantitatively characterize regional soil nutrient gradients in different climatic regions, but no study has yet been done in the subalpine coastal forest (Mountain Hemlock zone). Influenced by a maritime subalpine boreal climate, high-elevation coastal soils differ from low-elevation soils by having a thicker forest ...
Urwald Rothwald is an old-growth forest of 400 ha located in the Limestone Alps of Lower Austria.... more Urwald Rothwald is an old-growth forest of 400 ha located in the Limestone Alps of Lower Austria. It is now within the International Union for Conservation of Nature (IUCN) Wilderness Area Dürrenstein. The article describes the exploitation history of the area to explain why the forest was able to remain intact for many centuries. Probable reasons include legal disputes over land use between monasteries. In 1875 Albert Rothschild decided to ensure that it continue to be excluded from forest use long-term.
To determine the influence of elevation and year-to-year climatic fluctuations on radial growth a... more To determine the influence of elevation and year-to-year climatic fluctuations on radial growth and tree-ring properties of Abies lasiocarpa, we sampled dominant trees in 49 second-growth stands on mesic sites in British Columbia. The earlywood, latewood, and total ring width, and latewood and maximum density decreased significantly with increasing elevation. Since no significant trend was observed for latewood percentage and ring density, decline in maximum density will have minor impacts on wood quality of high and low-elevation Abies lasiocarpa. The correlation and response functions indicated that response to climatic factors changed with elevation. Although mesic sites within the study area were not expected to be water deficient, ring width decreased with the occurrence of warm and dry spring weather in low-elevation. Low summer temperature limited ring width in high-elevation and maximum latewood density and latewood width in low-and high-elevation, albeit the relationship was much stronger in highelevation. Abies lasiocarpa / dendrochronology / radial growth / response function / wood density Résumé-Caractéristiques des cernes annuels chez Abies lasiocarpa ((Hook.) Nutt.) en fonction de l'altitude et des variations climatiques. On a échantillonné les arbres dominants au sein de 49 peuplements de seconde venue sur des stations moyennes de la Colombie-Britannique, afin de déterminer l'influence de l'altitude et des variations climatiques sur la croissance radiale et les propriétés des cernes annuels chez Abies lasiocarpa. La largeur de la zone de bois initial, de la zone de bois final ainsi que la largeur totale du cerne, de même que la densité du bois final et la densité maximale diminuent de façon significative lorsque l'altitude augmente. Puisqu'on n'observe aucune tendance significative pour le pourcentage de bois final ou la densité des cernes, une baisse de la densité maximale n'aura qu'un impact mineur sur la qualité du bois chez Abies lasiocarpa, en haute comme en basse altitude. Les études de corrélation et de fonction reactionnaires indiquent que la réponse aux facteurs climatiques varie selon l'altitude. La largeur des cernes diminue en l'occurrence d'un printemps chaud et sec en basse altitude, bien qu'on se n'ait pas attendu une pénurie d'eau sur des stations moyennes de la région d'études. Des températures estivales basses limitent la largeur des cernes à haute altitude ainsi que la densité maximale du bois final et la largeur du cerne du bois final chez les arbres à faible et à haute altitude, bien que la relation soit plus forte à haute altitude.
ABSTRACT This study examines the influence of climate on tree-ring properties of several major tr... more ABSTRACT This study examines the influence of climate on tree-ring properties of several major tree species: Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and lodgepole pine (Pinus contorta var. latifolia Dougl. ex Loud.). Our three objectives were to determine how (1) tree-ring properties change along an elevation gradient, (2) short-term climatic influences are correlated with tree-ring properties, and (3) long-term climatic influence on tree-ring properties. Forest Sciences, Dept of Peer-Reviewed
GAIA - Ecological Perspectives for Science and Society, 2010
Disturbances are considered driving forces of forest development, however, very little is known a... more Disturbances are considered driving forces of forest development, however, very little is known about the disturbance histories of natural forests in Central Europe. As part of a larger study on the long-term dynamics, the disturbance regime was studied of a spruce-fir-beech virgin forest situated in Austria. The approaches presented here included age structure analysis, development of a disturbance chronology based on dendroecological analysis, and calculation of gap (size) distribution and gap formation and closure rates using a time series of aerial photographs. The majority of the gaps were smaller than 400 m 2 . However gap-formation rates were significantly higher than gap-closure rates. Furthermore, the discontinuous age class distributions and the occurrence of peaks in the disturbance chronology indicated the occurrence of intermediate disturbances (400 m 2 to 0.5 ha) or possibly synchronized fine-scale disturbances and their import-ance for stand dynamics. Our results unde...
Oikos, 2004
We present a critical review of current trends in research of spatio-temporal development of fore... more We present a critical review of current trends in research of spatio-temporal development of forests. The paper addresses (1) field methods for the development of spatially-explicit models of forest dynamics and their integration in models of forest dynamics, (2) strengths and limitations of traditional patch models versus spatially-explicit, individual-based models, and (3) the potential for moment-based methods in the analysis of forest dynamics. These topics are discussed with reference to their potential for solving open questions in the studies of forest dynamics. The study of spatio-temporal processes provides a link between pattern and process in plant communities, and plays a crucial role in understanding ecosystem dynamics. In the last decade, the development of spatially-explicit, individual-based models shifted the focus of forest dynamics modelling from the dynamics of discrete patches to the interactions among individual organisms, thus encapsulating the theory of "neighbourhood" dynamics. In turn, the stochastic properties and the complexity of spatially-explicit, individual-based models gave rise to the development of a new suite of socalled moment-based models. These new models describe the dynamics of individuals and of pairs of individuals in terms of their densities, thus directly capturing second-order information on spatial structure. So far, this approach has not been applied to forests; we indicate extensions needed for such applications. Moment-based models may be an important complement to spatially explicit individual-based models in developing a general spatial theory of forest dynamics. However, both kinds of models currently focus on fine scales, whereas a critical issue in forest dynamics is to understand the interaction of fine-scale processes with coarser-scale disturbances. To obtain a more complete picture of forest dynamics, the relevant links and interactions between fine-, intermediate-, and coarse-scale processes ought to be identified. Intensive links between modelling work and field studies
Canadian Journal of Soil Science, 1998
To determine whether field-identified soil nutrient regimes (SNRs) can be characterized and segre... more To determine whether field-identified soil nutrient regimes (SNRs) can be characterized and segregated by direct soil nutrient measures, we collected samples of forest floor and mineral soil (0 to 30 cm) from a wide range of forest sites throughout the Engelmann Spruce — Subalpine Fir (ESSF) zone of British Columbia. The samples were analyzed for acidity, total C, total N, mineralizable N, and extractable Ca, Mg, K, P, and SO4-S. The study sites were stratified according to an a priori field classification (SNRs) and an a posteriori classification derived from quantitative classification (groups) using all direct measures of nutrients as discriminating variables. The two classification methods had 72% agreement. Regardless of the classification, nitrogen-related variables (C:N ratio, total N, and mineralizable N) in the mineral soil segregated best among SNRs or groups indicating the presence of a steep, N-driven regional soil nutrient gradient. Multiple regression models using SNRs...
Annals of Forest Science, 2000
To determine the influence of elevation and year-to-year climatic fluctuations on radial growth a... more To determine the influence of elevation and year-to-year climatic fluctuations on radial growth and tree-ring properties of Abies lasiocarpa, we sampled dominant trees in 49 second-growth stands on mesic sites in British Columbia. The earlywood, latewood, and total ring width, and latewood and maximum density decreased significantly with increasing elevation. Since no significant trend was observed for latewood percentage and ring density, decline in maximum density will have minor impacts on wood quality of high and low-elevation Abies lasiocarpa. The correlation and response functions indicated that response to climatic factors changed with elevation. Although mesic sites within the study area were not expected to be water deficient, ring width decreased with the occurrence of warm and dry spring weather in low-elevation. Low summer temperature limited ring width in high-elevation and maximum latewood density and latewood width in low-and high-elevation, albeit the relationship was much stronger in highelevation. Abies lasiocarpa / dendrochronology / radial growth / response function / wood density Résumé-Caractéristiques des cernes annuels chez Abies lasiocarpa ((Hook.) Nutt.) en fonction de l'altitude et des variations climatiques. On a échantillonné les arbres dominants au sein de 49 peuplements de seconde venue sur des stations moyennes de la Colombie-Britannique, afin de déterminer l'influence de l'altitude et des variations climatiques sur la croissance radiale et les propriétés des cernes annuels chez Abies lasiocarpa. La largeur de la zone de bois initial, de la zone de bois final ainsi que la largeur totale du cerne, de même que la densité du bois final et la densité maximale diminuent de façon significative lorsque l'altitude augmente. Puisqu'on n'observe aucune tendance significative pour le pourcentage de bois final ou la densité des cernes, une baisse de la densité maximale n'aura qu'un impact mineur sur la qualité du bois chez Abies lasiocarpa, en haute comme en basse altitude. Les études de corrélation et de fonction reactionnaires indiquent que la réponse aux facteurs climatiques varie selon l'altitude. La largeur des cernes diminue en l'occurrence d'un printemps chaud et sec en basse altitude, bien qu'on se n'ait pas attendu une pénurie d'eau sur des stations moyennes de la région d'études. Des températures estivales basses limitent la largeur des cernes à haute altitude ainsi que la densité maximale du bois final et la largeur du cerne du bois final chez les arbres à faible et à haute altitude, bien que la relation soit plus forte à haute altitude.
One of the key factors in the site classification of the biogeoclimatic ecosystem classification ... more One of the key factors in the site classification of the biogeoclimatic ecosystem classification is soil nutrient regime. Soil nutrient regime (SNR) represents the amount of essential soil nutrients available to plants over a period of several years. SNRs classes are assessed based on field identifiable (qualitative) criteria, not using quantitative measures. There have been several studies that attempted to quantitatively characterize regional soil nutrient gradients in the Coastal Western Hemlock (CWH) zone. In the study summarized here, the soils are influenced by a perhumid cool mesothermal climate. The objective of the study was to examine relationships between soil chemical properties and field-estimated SNRs.
Following an exploratory examination of the variation in the height growth pattern using a single... more Following an exploratory examination of the variation in the height growth pattern using a single- valued ratio, conventional polymorphic and climate-specific height growth and site index models were developed for Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes). The models were developed from stem analysis data obtained from 67 study plots, which were located over the entire elevation-continentality range of the species in southern coastal British Columbia. When tested against an independent data set consisting of 31 plots, the climate-specific models improved height and site index prediction compared to the conventional polymorphic models. The previ- ously available model for Pacific silver fir was biased. It overestimated height before, and underes- timated it beyond, the index age. It also underestimated height on low-productivity sites and over- estimated it on high-productivity sites. In consequence, when this model was used to estimate site index from top-height a...
Journal of Vegetation Science, 2005
We were interested if and how variation in frequency and/or size of disturbances affect the dynam... more We were interested if and how variation in frequency and/or size of disturbances affect the dynamics of a montane old-growth forest in Central Europe. Location: The forest, co-dominated by Fagus sylvatica, Picea abies and Abies alba, is located in Lower Austria and represents one of the few sizable virgin forests in Central Europe. Methods: We extracted cores from 100 trees using systematic grid sampling (grid cell size 10 m × 10 m) on each of four 1-ha plots distributed across the old-growth remnant of 300 ha. We inferred disturbance events from rapid early growth and release events. For defining release criteria, we applied the boundary line method. We investigated the spatial structure of current age and gap distributions and past disturbance events in grid cells, using a pair density statistic. Results: The disturbance histories indicate decades with peaks and also extended periods without disturbance. Some peaks occurred synchronously at three of the four plots (1910s, 1930s, 1960s and 1980s). Peaks and gaps in the disturbance chronologies widely agreed with peaks and gaps in the age distributions. Most disturbance events during single decades showed a random spatial distribution. Conclusions: There is considerable variation in disturbance frequency and/or severity over time. Most disturbance events will rather thin the stand than clear larger areas at once. Following scattered disturbance two pathways occur: (1) gap expansion leading to creation of larger gaps, and (2) gap closure by lateral encroachment or by subcanopy trees growing into the canopy.
Geoderma, Jul 1, 2001
concentrations appeared to be unrelated to changes in continentality within the study area. These... more concentrations appeared to be unrelated to changes in continentality within the study area. These findings agree with the results of previous studies suggesting that mineralizable-N of the mineral soil is the best property for a quantitative characterization of a soil nutrient gradient, and, hence for quantification of field-estimated SNRs. Field-estimated SNRs were also good predictors of site index as they explained the variation in site index of Pacific silver fir similarly well as total N and CrN ratio. However, the absence of a relationship between mineralizable-N and the Pacific silver fir site index requires a further study of plant-soil relationships in the area.
We present a critical review of current trends in research of spatio-temporal development of fore... more We present a critical review of current trends in research of spatio-temporal development of forests. The paper addresses (1) field methods for the development of spatially-explicit models of forest dynamics and their integration in models of forest dynamics, (2) strengths and limitations of traditional patch models versus spatiallyexplicit, individual-based models, and (3) the potential for moment-based methods in the analysis of forest dynamics. These topics are discussed with reference to their potential for solving open questions in the studies of forest dynamics. The study of spatio-temporal processes provides a link between pattern and process in plant communities, and plays a crucial role in understanding ecosystem dynamics. In the last decade, the development of spatially-explicit, individual-based models shifted the focus of forest dynamics modelling from the dynamics of discrete patches to the interactions among individual organisms, thus encapsulating the theory of ''neighbourhood'' dynamics. In turn, the stochastic properties and the complexity of spatially-explicit, individual-based models gave rise to the development of a new suite of so-called moment-based models. These new models describe the dynamics of individuals and of pairs of individuals in terms of their densities, thus directly capturing second-order information on spatial structure. So far, this approach has not been applied to forests; we indicate extensions needed for such applications. Moment-based models may be an important complement to spatially explicit individual-based models in developing a general spatial theory of forest dynamics. However, both kinds of models currently focus on fine scales, whereas a critical issue in forest dynamics is to understand the interaction of fine-scale processes with coarser-scale disturbances. To obtain a more complete picture of forest dynamics, the relevant links and interactions between fine-, intermediate-, and coarse-scale processes ought to be identified. Intensive links between modelling work and field studies designed across different scales are a promising means to create a new perspective on forest dynamics.
Height growth and site index models for Pacific silver fir in southwestern British Columbia Heigh... more Height growth and site index models for Pacific silver fir in southwestern British Columbia Height growth and site index models for Pacific silver fir in southwestern British Columbia Following an exploratory examination of the variation in the height growth pattern using a single-valued ratio, conventional polymorphic and climate-specific height growth and site index models were developed for Pacific silver fir (Abies amabilis [Dougl. ex Loud.] Forbes). The models were developed from stem analysis data obtained from 67 study plots, which were located over the entire elevation-continentality range of the species in southern coastal British Columbia. When tested against an independent data set consisting of 31 plots, the climate-specific models improved height and site index prediction compared to the conventional polymorphic models. The previ-ously available model for Pacific silver fir was biased. It overestimated height before, and underes-timated it beyond, the index age. It also...
This study examines the influence of climate on tree-ring properties of several major tree specie... more This study examines the influence of climate on tree-ring properties of several major tree species: Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and lodgepole pine (Pinus contorta var. latifolia Dougl. ex Loud.). Our three objectives were to determine how (1) tree-ring properties change along an elevation gradient, (2) short-term climatic influences are correlated with tree-ring properties, and (3) long-term climatic influence on tree-ring properties.Forestry, Faculty ofForest Sciences, Department ofReviewedFacult
Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species ... more Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in coastal forests of B.C. Its range extends from sea-level to almost timberline, and from the hypermaritime region on the west coast of Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. With this relatively wide climatic amplitude, a large variability in the height growth pattern of Pacific silver fir can be expected, since climate is considered to be the most influential determinant of the trajectory of height over age of forest trees. This variability, however, is not reflected in the height growth curves and site index tables used to estimate Pacific silver fir site index, since the curves and tables were developed from low-elevation stands on Vancouver Island. Consequently, when these curves and tables are applied to high-elevation or submaritime stands, we get biased estimates of site index. Accurate estimates of site index are necessary for ...
Site classification in the biogeoclimatic ecosystem classification system is based on three diffe... more Site classification in the biogeoclimatic ecosystem classification system is based on three differentiating properties: climatic regimes (expressed by biogeoclimatic subzones or variants), soil moisture regimes (SMRs), and soil nutrient regimes (SNRs). A SNR represents a segment of a regional soil nutrient gradient, i.e., soils which provide similar levels of plant-available nutrients over a long period. SNRs are identified in the field using a number of easily observable soil morphological properties and indicator plant species. However, we need to know to what extent soil nutrient properties support these indirect field-estimates. There have been several studies that quantitatively characterize regional soil nutrient gradients in different climatic regions, but no study has yet been done in the subalpine coastal forest (Mountain Hemlock zone). Influenced by a maritime subalpine boreal climate, high-elevation coastal soils differ from low-elevation soils by having a thicker forest ...
Urwald Rothwald is an old-growth forest of 400 ha located in the Limestone Alps of Lower Austria.... more Urwald Rothwald is an old-growth forest of 400 ha located in the Limestone Alps of Lower Austria. It is now within the International Union for Conservation of Nature (IUCN) Wilderness Area Dürrenstein. The article describes the exploitation history of the area to explain why the forest was able to remain intact for many centuries. Probable reasons include legal disputes over land use between monasteries. In 1875 Albert Rothschild decided to ensure that it continue to be excluded from forest use long-term.
To determine the influence of elevation and year-to-year climatic fluctuations on radial growth a... more To determine the influence of elevation and year-to-year climatic fluctuations on radial growth and tree-ring properties of Abies lasiocarpa, we sampled dominant trees in 49 second-growth stands on mesic sites in British Columbia. The earlywood, latewood, and total ring width, and latewood and maximum density decreased significantly with increasing elevation. Since no significant trend was observed for latewood percentage and ring density, decline in maximum density will have minor impacts on wood quality of high and low-elevation Abies lasiocarpa. The correlation and response functions indicated that response to climatic factors changed with elevation. Although mesic sites within the study area were not expected to be water deficient, ring width decreased with the occurrence of warm and dry spring weather in low-elevation. Low summer temperature limited ring width in high-elevation and maximum latewood density and latewood width in low-and high-elevation, albeit the relationship was much stronger in highelevation. Abies lasiocarpa / dendrochronology / radial growth / response function / wood density Résumé-Caractéristiques des cernes annuels chez Abies lasiocarpa ((Hook.) Nutt.) en fonction de l'altitude et des variations climatiques. On a échantillonné les arbres dominants au sein de 49 peuplements de seconde venue sur des stations moyennes de la Colombie-Britannique, afin de déterminer l'influence de l'altitude et des variations climatiques sur la croissance radiale et les propriétés des cernes annuels chez Abies lasiocarpa. La largeur de la zone de bois initial, de la zone de bois final ainsi que la largeur totale du cerne, de même que la densité du bois final et la densité maximale diminuent de façon significative lorsque l'altitude augmente. Puisqu'on n'observe aucune tendance significative pour le pourcentage de bois final ou la densité des cernes, une baisse de la densité maximale n'aura qu'un impact mineur sur la qualité du bois chez Abies lasiocarpa, en haute comme en basse altitude. Les études de corrélation et de fonction reactionnaires indiquent que la réponse aux facteurs climatiques varie selon l'altitude. La largeur des cernes diminue en l'occurrence d'un printemps chaud et sec en basse altitude, bien qu'on se n'ait pas attendu une pénurie d'eau sur des stations moyennes de la région d'études. Des températures estivales basses limitent la largeur des cernes à haute altitude ainsi que la densité maximale du bois final et la largeur du cerne du bois final chez les arbres à faible et à haute altitude, bien que la relation soit plus forte à haute altitude.
ABSTRACT This study examines the influence of climate on tree-ring properties of several major tr... more ABSTRACT This study examines the influence of climate on tree-ring properties of several major tree species: Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and lodgepole pine (Pinus contorta var. latifolia Dougl. ex Loud.). Our three objectives were to determine how (1) tree-ring properties change along an elevation gradient, (2) short-term climatic influences are correlated with tree-ring properties, and (3) long-term climatic influence on tree-ring properties. Forest Sciences, Dept of Peer-Reviewed
GAIA - Ecological Perspectives for Science and Society, 2010
Disturbances are considered driving forces of forest development, however, very little is known a... more Disturbances are considered driving forces of forest development, however, very little is known about the disturbance histories of natural forests in Central Europe. As part of a larger study on the long-term dynamics, the disturbance regime was studied of a spruce-fir-beech virgin forest situated in Austria. The approaches presented here included age structure analysis, development of a disturbance chronology based on dendroecological analysis, and calculation of gap (size) distribution and gap formation and closure rates using a time series of aerial photographs. The majority of the gaps were smaller than 400 m 2 . However gap-formation rates were significantly higher than gap-closure rates. Furthermore, the discontinuous age class distributions and the occurrence of peaks in the disturbance chronology indicated the occurrence of intermediate disturbances (400 m 2 to 0.5 ha) or possibly synchronized fine-scale disturbances and their import-ance for stand dynamics. Our results unde...
Oikos, 2004
We present a critical review of current trends in research of spatio-temporal development of fore... more We present a critical review of current trends in research of spatio-temporal development of forests. The paper addresses (1) field methods for the development of spatially-explicit models of forest dynamics and their integration in models of forest dynamics, (2) strengths and limitations of traditional patch models versus spatially-explicit, individual-based models, and (3) the potential for moment-based methods in the analysis of forest dynamics. These topics are discussed with reference to their potential for solving open questions in the studies of forest dynamics. The study of spatio-temporal processes provides a link between pattern and process in plant communities, and plays a crucial role in understanding ecosystem dynamics. In the last decade, the development of spatially-explicit, individual-based models shifted the focus of forest dynamics modelling from the dynamics of discrete patches to the interactions among individual organisms, thus encapsulating the theory of "neighbourhood" dynamics. In turn, the stochastic properties and the complexity of spatially-explicit, individual-based models gave rise to the development of a new suite of socalled moment-based models. These new models describe the dynamics of individuals and of pairs of individuals in terms of their densities, thus directly capturing second-order information on spatial structure. So far, this approach has not been applied to forests; we indicate extensions needed for such applications. Moment-based models may be an important complement to spatially explicit individual-based models in developing a general spatial theory of forest dynamics. However, both kinds of models currently focus on fine scales, whereas a critical issue in forest dynamics is to understand the interaction of fine-scale processes with coarser-scale disturbances. To obtain a more complete picture of forest dynamics, the relevant links and interactions between fine-, intermediate-, and coarse-scale processes ought to be identified. Intensive links between modelling work and field studies
Canadian Journal of Soil Science, 1998
To determine whether field-identified soil nutrient regimes (SNRs) can be characterized and segre... more To determine whether field-identified soil nutrient regimes (SNRs) can be characterized and segregated by direct soil nutrient measures, we collected samples of forest floor and mineral soil (0 to 30 cm) from a wide range of forest sites throughout the Engelmann Spruce — Subalpine Fir (ESSF) zone of British Columbia. The samples were analyzed for acidity, total C, total N, mineralizable N, and extractable Ca, Mg, K, P, and SO4-S. The study sites were stratified according to an a priori field classification (SNRs) and an a posteriori classification derived from quantitative classification (groups) using all direct measures of nutrients as discriminating variables. The two classification methods had 72% agreement. Regardless of the classification, nitrogen-related variables (C:N ratio, total N, and mineralizable N) in the mineral soil segregated best among SNRs or groups indicating the presence of a steep, N-driven regional soil nutrient gradient. Multiple regression models using SNRs...
Annals of Forest Science, 2000
To determine the influence of elevation and year-to-year climatic fluctuations on radial growth a... more To determine the influence of elevation and year-to-year climatic fluctuations on radial growth and tree-ring properties of Abies lasiocarpa, we sampled dominant trees in 49 second-growth stands on mesic sites in British Columbia. The earlywood, latewood, and total ring width, and latewood and maximum density decreased significantly with increasing elevation. Since no significant trend was observed for latewood percentage and ring density, decline in maximum density will have minor impacts on wood quality of high and low-elevation Abies lasiocarpa. The correlation and response functions indicated that response to climatic factors changed with elevation. Although mesic sites within the study area were not expected to be water deficient, ring width decreased with the occurrence of warm and dry spring weather in low-elevation. Low summer temperature limited ring width in high-elevation and maximum latewood density and latewood width in low-and high-elevation, albeit the relationship was much stronger in highelevation. Abies lasiocarpa / dendrochronology / radial growth / response function / wood density Résumé-Caractéristiques des cernes annuels chez Abies lasiocarpa ((Hook.) Nutt.) en fonction de l'altitude et des variations climatiques. On a échantillonné les arbres dominants au sein de 49 peuplements de seconde venue sur des stations moyennes de la Colombie-Britannique, afin de déterminer l'influence de l'altitude et des variations climatiques sur la croissance radiale et les propriétés des cernes annuels chez Abies lasiocarpa. La largeur de la zone de bois initial, de la zone de bois final ainsi que la largeur totale du cerne, de même que la densité du bois final et la densité maximale diminuent de façon significative lorsque l'altitude augmente. Puisqu'on n'observe aucune tendance significative pour le pourcentage de bois final ou la densité des cernes, une baisse de la densité maximale n'aura qu'un impact mineur sur la qualité du bois chez Abies lasiocarpa, en haute comme en basse altitude. Les études de corrélation et de fonction reactionnaires indiquent que la réponse aux facteurs climatiques varie selon l'altitude. La largeur des cernes diminue en l'occurrence d'un printemps chaud et sec en basse altitude, bien qu'on se n'ait pas attendu une pénurie d'eau sur des stations moyennes de la région d'études. Des températures estivales basses limitent la largeur des cernes à haute altitude ainsi que la densité maximale du bois final et la largeur du cerne du bois final chez les arbres à faible et à haute altitude, bien que la relation soit plus forte à haute altitude.
One of the key factors in the site classification of the biogeoclimatic ecosystem classification ... more One of the key factors in the site classification of the biogeoclimatic ecosystem classification is soil nutrient regime. Soil nutrient regime (SNR) represents the amount of essential soil nutrients available to plants over a period of several years. SNRs classes are assessed based on field identifiable (qualitative) criteria, not using quantitative measures. There have been several studies that attempted to quantitatively characterize regional soil nutrient gradients in the Coastal Western Hemlock (CWH) zone. In the study summarized here, the soils are influenced by a perhumid cool mesothermal climate. The objective of the study was to examine relationships between soil chemical properties and field-estimated SNRs.
Following an exploratory examination of the variation in the height growth pattern using a single... more Following an exploratory examination of the variation in the height growth pattern using a single- valued ratio, conventional polymorphic and climate-specific height growth and site index models were developed for Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes). The models were developed from stem analysis data obtained from 67 study plots, which were located over the entire elevation-continentality range of the species in southern coastal British Columbia. When tested against an independent data set consisting of 31 plots, the climate-specific models improved height and site index prediction compared to the conventional polymorphic models. The previ- ously available model for Pacific silver fir was biased. It overestimated height before, and underes- timated it beyond, the index age. It also underestimated height on low-productivity sites and over- estimated it on high-productivity sites. In consequence, when this model was used to estimate site index from top-height a...