Effects of Release from Suppression on Hydraulic Architecture, Photosynthetic Capacity and Functional Wood Characteristics in Douglas-fir and Western Hemlock PDF Download
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Author: Heidi Renninger
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 204
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Book Description
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), a shade intolerant species, and western hemlock (Tsuga heterophylla (Raf.) Sarg.), a shade tolerant species, were compared to learn more about the temporal pattern of release from suppression in both species, whether hydraulic architecture or photosynthetic capacity constrain release and how wood functional properties change after release from suppression. The study was conducted in 10-20 year old Douglas-fir and western hemlocks, either in a site that had been thinned to release suppressed trees or in a site that remained unthinned. Douglas-fir had lower height growth (from 1998-2003) and lower relative height growth (height growth from 1998-2003/height in 1998) than western hemlock. However, the relative height growth of released vs. suppressed trees was much higher in Douglas-fir (130%) than western hemlock (65%), suggesting that although height growth was lower, Douglas-fir did indeed release from suppression. Release seems to be constrained initially by photosynthetic capacity in Douglas-fir and western hemlock. In Douglas-fir released trees had 14 times the leaf area and 1.5 times the nitrogen per unit leaf area (Narea) as suppressed trees. Needles on released western hemlock trees had approximately twice the maximum assimilation rate (Amax) at ambient [CO2] as suppressed trees and did not exhibit photoinhibition at the highest light levels. Hydraulic architecture appears to constrain further release from suppression in Douglas-fir more so than western hemlock after the increase in leaf area, leaf N content and overall photosynthetic capacity. Released trees had significantly less negative foliar?13C values and there was also a positive relationship between leaf area:sapwood area ratios and?13C suggesting that trees with more leaf area for a given sapwood area experienced a stomatal limitation on carbon gain. Growth of released trees, thus, may have been limited by stomatal constraints on carbon gain despite a doubling of Amax after release. Nonetheless, trees exhibited no significant differences between the leaf-specific conductivities (KL) of suppressed vs. released trees of either species. However, leaf-specific root conductance (kRL) was significantly greater in suppressed Douglas-fir compared to released trees. Functional wood characteristics were also much different in trees released from suppression and those that remained suppressed. Growth ring widths in released trees increased by 370% for Douglas-fir and 300% for western hemlock, while specific conductivity (Ks) increased by 182% for Douglas-fir and 42% for western hemlock compared to suppressed trees. Earlywood width was approximately four times greater in released than suppressed trees of both species, whereas the relative increase in latewood width between suppressed and released trees was much greater in Douglas-fir than in western hemlock. Latewood proportion decreased by 21% in released Douglas-fir and by 47% released western hemlock compared to suppressed trees. Tracheids were 25% wider and 11% longer in released Douglas-fir saplings than suppressed saplings, whereas in western hemlock released saplings had 19% wider tracheids that were approximately the same length as suppressed saplings. Wood moisture content was 66% higher in released Douglas-fir compared to suppressed Douglas-fir and 41% higher in released western hemlock compared to suppressed western hemlock. Wood density decreased from 0.57 to 0.47 g cm-3 in Douglas-fir trees released from suppression and from 0.50 to 0.45 g cm-3 in western hemlock trees released from suppression. Therefore, it appears that as management patterns switch from even-age systems to uneven-age systems, both Douglas-fir and western hemlock will be able to release from suppression and the wood of released trees will be of good quality for most applications.
Author: Heidi Renninger
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 204
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Book Description
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), a shade intolerant species, and western hemlock (Tsuga heterophylla (Raf.) Sarg.), a shade tolerant species, were compared to learn more about the temporal pattern of release from suppression in both species, whether hydraulic architecture or photosynthetic capacity constrain release and how wood functional properties change after release from suppression. The study was conducted in 10-20 year old Douglas-fir and western hemlocks, either in a site that had been thinned to release suppressed trees or in a site that remained unthinned. Douglas-fir had lower height growth (from 1998-2003) and lower relative height growth (height growth from 1998-2003/height in 1998) than western hemlock. However, the relative height growth of released vs. suppressed trees was much higher in Douglas-fir (130%) than western hemlock (65%), suggesting that although height growth was lower, Douglas-fir did indeed release from suppression. Release seems to be constrained initially by photosynthetic capacity in Douglas-fir and western hemlock. In Douglas-fir released trees had 14 times the leaf area and 1.5 times the nitrogen per unit leaf area (Narea) as suppressed trees. Needles on released western hemlock trees had approximately twice the maximum assimilation rate (Amax) at ambient [CO2] as suppressed trees and did not exhibit photoinhibition at the highest light levels. Hydraulic architecture appears to constrain further release from suppression in Douglas-fir more so than western hemlock after the increase in leaf area, leaf N content and overall photosynthetic capacity. Released trees had significantly less negative foliar?13C values and there was also a positive relationship between leaf area:sapwood area ratios and?13C suggesting that trees with more leaf area for a given sapwood area experienced a stomatal limitation on carbon gain. Growth of released trees, thus, may have been limited by stomatal constraints on carbon gain despite a doubling of Amax after release. Nonetheless, trees exhibited no significant differences between the leaf-specific conductivities (KL) of suppressed vs. released trees of either species. However, leaf-specific root conductance (kRL) was significantly greater in suppressed Douglas-fir compared to released trees. Functional wood characteristics were also much different in trees released from suppression and those that remained suppressed. Growth ring widths in released trees increased by 370% for Douglas-fir and 300% for western hemlock, while specific conductivity (Ks) increased by 182% for Douglas-fir and 42% for western hemlock compared to suppressed trees. Earlywood width was approximately four times greater in released than suppressed trees of both species, whereas the relative increase in latewood width between suppressed and released trees was much greater in Douglas-fir than in western hemlock. Latewood proportion decreased by 21% in released Douglas-fir and by 47% released western hemlock compared to suppressed trees. Tracheids were 25% wider and 11% longer in released Douglas-fir saplings than suppressed saplings, whereas in western hemlock released saplings had 19% wider tracheids that were approximately the same length as suppressed saplings. Wood moisture content was 66% higher in released Douglas-fir compared to suppressed Douglas-fir and 41% higher in released western hemlock compared to suppressed western hemlock. Wood density decreased from 0.57 to 0.47 g cm-3 in Douglas-fir trees released from suppression and from 0.50 to 0.45 g cm-3 in western hemlock trees released from suppression. Therefore, it appears that as management patterns switch from even-age systems to uneven-age systems, both Douglas-fir and western hemlock will be able to release from suppression and the wood of released trees will be of good quality for most applications.
Author:
Publisher:
ISBN:
Category : Forest genetics
Languages : en
Pages : 772
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Author: David R. Woodruff
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 338
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Book Description
This dissertation investigated the impacts of tree height upon a range of physiological and structural characteristics of Douglas-fir foliage; relationships between structural and functional trends with height; and compensatory mechanisms that mitigate height-related growth constraints. Height-related trends in foliar physiological and anatomical characteristics were examined both within trees as well as between trees of different heights. Emphasis was placed on discovering the mechanistic nature of the observed growth constraints and adaptive strategies. This research was conducted in the interest of enhancing our knowledge of the causes of age- and size-related decline in forest productivity. The research conducted for this dissertation explored several previously uninvestigated mechanisms for size-related reductions in forest productivity that are associated with tree foliar structure and function. Height-related trends in foliar turgor associated with the gravitational hydrostatic pressure gradient were identified as well as subsequent impacts on leaf and shoot morphology. Osmotic potential declined with height providing evidence of osmotic adjustment to offset the height-related decline in leaf turgor. This osmotic adjustment occurred only seasonally, and not during the spring when turgor maintenance is most important for leaf expansion. Gradients in leaf turgor were reflected in height-related trends in leaf and shoot morphology. Previous work has documented height-related trends in foliar morphological characteristics and earlier studies have examined osmotic adjustment as an adaptation to drought and salinity stress. Height-related trends in foliar morphological characteristics have typically been attributed to light gradients along vertical profiles. The work in this dissertation is the first to evaluate the effects of the gravitational component of water potential on the osmotic, morphological and growth characteristics of foliage along a height gradient in tall trees. Trends in leaf hydraulic efficiency and safety along a height gradient were examined, and correlations between changes in leaf hydraulic conductance (Kleaf) and changes in stomatal conductance (gs) were identified that provided evidence of a control mechanism for gs. A consistent relationship was discovered between changes in Kleaf and gs providing evidence that leaf tracheid embolism is associated with stomatal closure during periods of declining water availability. Hydraulic vulnerability curves of foliage collected at different heights indicated that increased height is correlated with reduced hydraulic efficiency and increased hydraulic safety. These opposing trends suggest the existence of a compensatory mechanism in foliage that functions to reduce hydraulic vulnerability at the expense of transport capacity. The research in this dissertation is the first to examine the dynamic relationships between leaf hydraulics and stomatal behavior in temperate conifers, and the first to examine how these characteristics are affected by tree height. Height-related trends in leaf xylem anatomical characteristics were examined and strong correlations were identified between these anatomical characteristics and the patterns of leaf hydraulic efficiency and safety that were observed in previous work for this dissertation. Theoretical estimates of leaf hydraulic efficiency (Kleaf-theoretical) based upon the Hagen-Pouseille equation and measured leaf tracheid anatomical characteristics were strongly correlated with laboratory measurements of Kleaf, providing further evidence of a causal relationship between height-related trends in both leaf tracheid anatomical properties and leaf hydraulic function. Earlier studies have documented connections between leaf anatomical characteristics and leaf physiological characteristics such as correlations between leaf architecture and gas exchange and leaf architecture and transport efficiency. The research in this dissertation however, is the first to examine the impact of tree height on leaf anatomical characteristics and associated shoot physiological properties. Trends in gas-exchange along a height gradient were identified, independent of the immediate effects of path length and gravitational resistance. Photosynthesis under ambient [CO2] declined with height in a manner that was consistent with height-related trends in mesophyll anatomy and independent of leaf nitrogen content. Analyses of mesophyll resistance from assimilation versus internal CO2 concentration (A-Ci) curves indicated that height-related trends in mesophyll resistance were correlated with trends in both photosynthesis and mesophyll anatomy along a height gradient. Analyses of integrated and instantaneous water use efficiency indicated that height-related trends in integrated water use efficiency are attributable to the effects of path length and gravity on stomatal behavior as opposed to a height-related trend in intrinsic foliar properties. The research in this dissertation is the first to isolate the influence of height-related trends in foliar structure on different gas exchange properties such as assimilation and mesophyll conductance, independent of the direct effects of vertical gradients in xylem tension on stomatal and photosynthetic physiology.
Author: Frederick C. Meinzer
Publisher: Springer Science & Business Media
ISBN: 9400712421
Category : Nature
Languages : en
Pages : 511
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Book Description
Millions of trees live and grow all around us, and we all recognize the vital role they play in the world’s ecosystems. Publicity campaigns exhort us to plant yet more. Yet until recently comparatively little was known about the root causes of the physical changes that attend their growth. Since trees typically increase in size by three to four orders of magnitude in their journey to maturity, this gap in our knowledge has been a crucial issue to address. Here at last is a synthesis of the current state of our knowledge about both the causes and consequences of ontogenetic changes in key features of tree structure and function. During their ontogeny, trees undergo numerous changes in their physiological function, the structure and mechanical properties of their wood, and overall architecture and allometry. This book examines the central interplay between these changes and tree size and age. It also explores the impact these changes can have, at the level of the individual tree, on the emerging characteristics of forest ecosystems at various stages of their development. The analysis offers an explanation for the importance of discriminating between the varied physical properties arising from the nexus of size and age, as well as highlighting the implications these ontogenetic changes have for commercial forestry and climate change. This important and timely summation of our knowledge base in this area, written by highly respected researchers, will be of huge interest, not only to researchers, but also to forest managers and silviculturists.
Author:
Publisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 858
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Book Description
Author: John W.G. Cairney
Publisher: Springer Science & Business Media
ISBN: 3662068273
Category : Science
Languages : en
Pages : 377
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Book Description
Mycorrhiza - the symbiosis between plants and fungi - plays a key role in plant life. This book reviews for the first time the current knowledge of 15 individual genera of ectomycorrhizal fungi. It is unique in that each chapter is dedicated to a single fungal genus, each written by internationally recognized experts on the respective fungal genera. It is thus an invaluable reference source for researchers, students and practitioners in the fields of mycorrhizal biology, mycology, forestry, plant sciences and soil biology.
Author: William K. Smith
Publisher: Gulf Professional Publishing
ISBN: 9780126528701
Category : Nature
Languages : en
Pages : 426
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Book Description
Coniferous forests are among the most important of ecosystems. These forests are widespread and influence both the financial and biological health of our globe. This book focuses attention on conifers and how these trees acquire, allocate, and utilize the resources that sustain this crucial productivity. An international team of experts has surveyed and synthesized information from an expanding area of inquiry. The first half of the book describes how resources are acquired both by means of photosynthesis and through root systems. The latter half of the volume focuses upon how resources are stored and used. As conifers continue as a resource and ever increasingly important contributor to the regional and global environmental sustainability, this book will help establish how much sustainability can be expected and maintained.
Author: Therese M. Poland
Publisher: Springer Nature
ISBN: 3030453677
Category : Science
Languages : en
Pages : 455
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Book Description
This open access book describes the serious threat of invasive species to native ecosystems. Invasive species have caused and will continue to cause enormous ecological and economic damage with ever increasing world trade. This multi-disciplinary book, written by over 100 national experts, presents the latest research on a wide range of natural science and social science fields that explore the ecology, impacts, and practical tools for management of invasive species. It covers species of all taxonomic groups from insects and pathogens, to plants, vertebrates, and aquatic organisms that impact a diversity of habitats in forests, rangelands and grasslands of the United States. It is well-illustrated, provides summaries of the most important invasive species and issues impacting all regions of the country, and includes a comprehensive primary reference list for each topic. This scientific synthesis provides the cultural, economic, scientific and social context for addressing environmental challenges posed by invasive species and will be a valuable resource for scholars, policy makers, natural resource managers and practitioners.
Author: F. Halle
Publisher: Springer Science & Business Media
ISBN: 3642811906
Category : Science
Languages : en
Pages : 457
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Book Description
Author: Paul G. Jarvis
Publisher: Cambridge University Press
ISBN: 9780521584784
Category : Nature
Languages : en
Pages : 124
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Book Description
A comprehensive study of the response of the major European tree species to climate change.
