scholarly journals Scaling from single-point sap velocity measurements to stand transpiration in a multispecies deciduous forest: uncertainty sources, stand structure effect, and future scenarios

2015 ◽  
Vol 45 (11) ◽  
pp. 1489-1497 ◽  
Author(s):  
Virginia Hernandez-Santana ◽  
Adan Hernandez-Hernandez ◽  
Matthew A. Vadeboncoeur ◽  
Heidi Asbjornsen
Keyword(s):  
Water Use ◽  
Stand Structure ◽  
Deciduous Forest ◽  
Single Point ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Tree Size ◽  
Betula Alleghaniensis ◽  
Sapwood Area ◽  
Wide Range

A major challenge in studies estimating stand water use in mixed-species forests is how to effectively scale data from individual trees to the stand. This is the case for forest ecosystems in the northeastern USA where differences in water use among species and across different size classes have not been extensively studied, despite their relevance for a wide range of ecosystem services. Our objectives were to assess the importance of different sources of variability on transpiration upscaling and explore the potential impacts of future shifts in species composition on the forest water budget. We measured sap velocity in five tree species (Fagus grandifolia Ehrh., Acer rubrum L., Acer saccharum Marsh., Betula alleghaniensis Britton, and Betula papyrifera Marsh.) in a mature stand and a young stand in New Hampshire, USA. Our results showed that the greatest potential source of error was radial variability and that tree size was more important than species in determining sap velocity. Total sapwood area was demonstrated to exert a strong controlling influence on transpiration, varying depending on tree size and species. We conclude that the effect of potential species shifts on transpiration will depend on the sap velocity, determined not only by radial variation and tree size, but also by the sapwood area distribution in the stand.

Decennial growth and mortality following uniform partial cutting in yellow birch – conifer stands

2013 ◽  
Vol 43 (3) ◽  
pp. 224-233 ◽  
Author(s):  
Marcel Prévost ◽  
Daniel Dumais
Keyword(s):  
Stand Structure ◽  
Block Design ◽  
Abies Balsamea ◽  
Acer Rubrum ◽  
Basal Area ◽  
Betula Alleghaniensis ◽  
Red Maple ◽  
Yellow Birch ◽  
Partial Cutting ◽  
Tree Survival

Estimating residual tree survival and growth is crucial for evaluating the overall merit of partial harvesting. In this case study, we present the effects of different cutting intensities (0%, 40%, 50%, and 60% of merchantable (diameter at breast height ≥ 9.1 cm) basal area (BA)) on the response of residual trees in two mixed yellow birch (Betula alleghaniensis Britt.) – conifer stands in eastern Quebec, Canada. Primarily aimed at promoting regeneration establishment, the experiment was conducted in two sites 90 km apart (Armagh and Duchesnay), each one containing four replicates of treatments in a randomized block design. Mortality after cutting decreased with increasing BA removal, but losses were two to three times higher at Armagh (62–138 stems/ha) than at Duchesnay (22–88 stems/ha). Loss of conifer stems involved primarily balsam fir (Abies balsamea (L.) Mill.) under natural conditions (control), whereas fir and red spruce (Picea rubens Sarg.) were equally affected in partial cuts. Red maple (Acer rubrum L.) and paper birch (Betula papyrifera Marsh.) were lost regardless of treatment. As a whole, growth in merchantable BA increased with cutting intensity. Uniform partial cuts produced good BA growth response from conifers at Armagh (0.27–0.28 m2·ha−1·year−1) and from hardwoods at Duchesnay (0.16–0.25 m2·ha−1·year−1), whereas BA growth was negligible for both species groups in the control. We examine the role of species composition and stand structure before cutting in the response of residual trees.

Patterns in vertical distribution of foliage in young coastal Douglas-fir

1996 ◽  
Vol 26 (11) ◽  
pp. 1991-2005 ◽  
Author(s):  
Douglas A. Maguire ◽  
William S. Bennett
Keyword(s):  
Vertical Distribution ◽  
Leaf Area ◽  
Stand Structure ◽  
Douglas Fir ◽  
Parameter Estimates ◽  
Relative Height ◽  
Structure Variation ◽  
Sapwood Area ◽  
Forest Stand Structure ◽  
Wide Range

Total amount and vertical distribution of foliage represent important aspects of forest stand structure and its influence on dry matter productivity, forest microclimate, watershed properties, and habitat structure. Variation in foliage distribution was analyzed on trees and plots in a series of even-aged Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands scheduled for management under a wide range of silvicultural regimes. Branch-level foliage mass and foliage area equations were developed from a sample of 138 branches. These equations were applied to 27 trees on which the diameter and height of all live primary branches were measured, allowing estimation of both the total amount of foliage and its vertical distribution. A β-distribution was fitted to data describing the vertical distribution of foliage on each tree, and the resulting parameter estimates were modelled as functions of tree height, diameter at breast height, crown length, and relative height in the stand. Foliage area distribution tended to be shifted downward relative to foliage mass because of the expected increase in specific leaf area with depth into the crown. Similarly, the relative foliage distribution in terms of both mass and area was shifted downward as the tree became more dominant, or as relative height in the stand increased. In contrast, foliage on trees of similar relative height was shifted upward in response to the lower stand densities imposed by precommercial thinning. On the stand level, relative vertical distribution of foliage in the canopy was more peaked than would be implied by assuming a constant leaf area/sapwood area ratio throughout the composite tree crowns. Between-stand variation in vertical foliage distribution was dictated by differences in stand top height, height to crown base, and number of trees per hectare.

scholarly journals Carbon Sequestration in Mixed Deciduous Forests: The Influence of Tree Size and Species Composition Derived from Model Experiments

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 726
Author(s):  
Anne Holtmann ◽  
Andreas Huth ◽  
Felix Pohl ◽  
Corinna Rebmann ◽  
Rico Fischer
Keyword(s):  
Carbon Sequestration ◽  
Species Composition ◽  
Stand Structure ◽  
Deciduous Forest ◽  
Ecosystem Respiration ◽  
Carbon Fluxes ◽  
Tree Size ◽  
Small Scale ◽  
Forest Stand Structure ◽  
Large Trees

Forests play an important role in climate regulation due to carbon sequestration. However, a deeper understanding of forest carbon flux dynamics is often missing due to a lack of information about forest structure and species composition, especially for non-even-aged and species-mixed forests. In this study, we integrated field inventory data of a species-mixed deciduous forest in Germany into an individual-based forest model to investigate daily carbon fluxes and to examine the role of tree size and species composition for stand productivity. This approach enables to reproduce daily carbon fluxes derived from eddy covariance measurements (R2 of 0.82 for gross primary productivity and 0.77 for ecosystem respiration). While medium-sized trees (stem diameter 30–60 cm) account for the largest share (66%) of total productivity at the study site, small (0–30 cm) and large trees (>60 cm) contribute less with 8.3% and 25.5% respectively. Simulation experiments indicate that vertical stand structure and shading influence forest productivity more than species composition. Hence, it is important to incorporate small-scale information about forest stand structure into modelling studies to decrease uncertainties of carbon dynamic predictions.

Growth Responses of Northern Hardwoods to Fertilization

1979 ◽  
Vol 25 (4) ◽  
pp. 597-604
Author(s):  
R. Lea ◽  
W. C. Tierson ◽  
A. L. Leaf
Keyword(s):  
New York State ◽  
Volume Growth ◽  
Acer Rubrum ◽  
Basal Area ◽  
Fagus Grandifolia ◽  
Betula Alleghaniensis ◽  
Growth Responses ◽  
Growth Data ◽  
Stem Form ◽  
Cross Sectional

Abstract A 70-year-old thinned Fagus-Betula-Acer stand in the Adirondack Mountains of northern New York State was fertilized with varying amounts and combinations of N, P, K, and dolomitic limestone in the spring of 1976. Betula alleghaniensis, Acer saccharum, Acer rubrum, and Fagus grandifolia growth data were obtained for two growing seasons after fertilization. Comparisons were made within species and among treatments, expressed as basal area and cross-sectional area (at 5.27 m height) growth, specific volume growth, and stem form ratio. The overall results indicate that 275 kg/ha N significantly increases radial growth with minor responses to 138 kg/ha P and lime. Potassium additions, on the whole, did not significantly alter growth rates, and individually fertilized trees grew slightly more than trees receiving entire plot applications. No changes in stem form induced by fertilization have been detected. Forest Sci. 25:597-604.

scholarly journals Biochemical and molecular characterization of Alternaria alternata isolates highly resistant to procymidone from broccoli and cabbage

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Bingran Wang ◽  
Tiancheng Lou ◽  
Lingling Wei ◽  
Wenchan Chen ◽  
Longbing Huang ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Single Point ◽  
Sodium Dodecyl ◽  
Cross Resistance ◽  
Molecular Characteristics ◽  
Single Point Mutation ◽  
Wide Range ◽  
Significant Difference ◽  
Leaf Blights ◽  
High Level

AbstractAlternaria alternata, a causal agent of leaf blights and spots on a wide range of hosts, has a high risk of developing resistance to fungicides. Procymidone, a dicarboximide fungicide (DCF), has been widely used in controlling Alternaria leaf blights in China for decades. However, the resistance of A. alternata against DCFs has rarely been reported from crucifer plants. A total of 198 A. alternata isolates were collected from commercial fields of broccoli and cabbage during 2018–2019, and their sensitivities to procymidone were determined. Biochemical and molecular characteristics were subsequently compared between the high-level procymidone-resistant (ProHR) and procymidone-sensitive (ProS) isolates, and also between ProHR isolates from broccoli and cabbage. Compared with ProS isolates, the mycelial growth rate, sporulation capacity and virulence of most ProHR isolates were reduced; ProHR isolates displayed an increased sensitivity to osmotic stresses and a reduced sensitivity to sodium dodecyl sulfate (SDS); all ProHR isolates showed a reduced sensitivity to hydrogen peroxide (H2O2) except for the isolate B102. Correlation analysis revealed a positive cross-resistance between procymidone and iprodione, or fludioxonil. When treated with 10 μg/mL of procymidone, both mycelial intracellular glycerol accumulations (MIGAs) and relative expression of AaHK1 in ProS isolates were higher than those in ProHR isolates. Sequence alignment of AaHK1 from ten ProHR isolates demonstrated that five of them possessed a single-point mutation (P94A, V612L, E708K or Q924STOP), and four isolates had an insertion or a deletion in their coding regions. No significant difference in biochemical characteristics was observed among ProHR isolates from two different hosts, though mutations in AaHK1 of the cabbage-originated ProHR isolates were distinct from those of the broccoli-originated ProHR isolates.

scholarly journals Vegetation responses to interglacial warming in the Arctic: examples from Lake El'gygytgyn, Far East Russian Arctic

2013 ◽  
Vol 9 (3) ◽  
pp. 1211-1219 ◽  
Author(s):  
A. V. Lozhkin ◽  
P. M. Anderson
Keyword(s):  
Deciduous Forest ◽  
Russian Far East ◽  
Coniferous Forest ◽  
Far East ◽  
The Arctic ◽  
Dark Coniferous Forest ◽  
Vegetation Responses ◽  
Wide Range ◽  
Lake El’Gygytgyn ◽  
Shrub Tundra

Abstract. Preliminary analyses of Lake El'gygytgyn sediment indicate a wide range of ecosystem responses to warmer than present climates. While palynological work describing all interglacial vegetation is ongoing, sufficient data exist to compare recent warm events (the postglacial thermal maximum, PGTM, and marine isotope stage, MIS5) with "super" interglaciations (MIS11, MIS31). Palynological assemblages associated with these climatic optima suggest two types of vegetation responses: one dominated by deciduous taxa (PGTM, MIS5) and the second by evergreen conifers (MIS11, MIS31). MIS11 forests show a similarity to modern Picea–Larix–Betula–Alnus forests of Siberia. While dark coniferous forest also characterizes MIS31, the pollen taxa show an affinity to the boreal forest of the lower Amur valley (southern Russian Far East). Despite vegetation differences during these thermal maxima, all glacial–interglacial transitions are alike, being dominated by deciduous woody taxa. Initially Betula shrub tundra established and was replaced by tundra with tree-sized shrubs (PGTM), Betula woodland (MIS5), or Betula–Larix (MIS11, MIS31) forest. The consistent occurrence of deciduous forest and/or high shrub tundra before the incidence of maximum warmth underscores the importance of this biome for modeling efforts. The El'gygytgyn data also suggest a possible elimination or massive reduction of Arctic plant communities under extreme warm-earth scenarios.

scholarly journals Usability Assessment for the Enhancement of Quality of a Web Portal Interface

2019 ◽  
Vol 9 (1) ◽  
pp. 1636-1640
Keyword(s):  
Research Group ◽  
Single Point ◽  
Portal System ◽  
Web Portal ◽  
Web Based ◽  
Academic Administration ◽  
Usability Assessment ◽  
Wide Range ◽  
Applied Informatics

A web portal can be defined as a personalized, single point of access to information, resources and services covering a wide range of topic. Based on some researches, a system based on the internet can improve the work efficiency to some extent and provide all kinds of academic administration information timely. As to establish the intended function, usability is a crucial factor to be embarked on. This will ensure that the users are attracted to use the portal by increasing the relationship between the users and the portal’s interface. The Applied Informatics Research Group (AIRG) is the group assigned by the Faculty of Computer Science and Information Technology (FSKTM) to manage the Research Group Portal System (RGPS) that is the sample used in this research. The RGPS is a web-based system that allows collaboration among the users; to locate, store, use and share their knowledge. The main objective of this research is to obtain the feedbackfrom the users regarding the usability of the RGPS that is deterring them from optimizing the usage of this system. Surveys and questionnaires are used to evaluate and the output acts an input to modify the interface of the RGPS. Again, validation will be done to weight the users’ experience with the modified user interface.

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