Boreal forest ecosystem dynamics. I. A new spatial model

2000 ◽  
Vol 30 (6) ◽  
pp. 998-1009 ◽  
Author(s):  
John Yarie
Keyword(s):  
Forest Ecosystem ◽  
Picea Glauca ◽  
Forest Growth ◽  
Ecosystem Dynamics ◽  
Spatial Context ◽  
Ecosystem Functions ◽  
Individual Tree ◽  
Microbial Efficiency ◽  
State Factor

Modeling the biology of forest ecosystems has been devoted to a combination of theoretical and empirical approaches representing the function of a forest ecosystem generally within an undefined spatial context. Moving to a large spatial context will require the use of theoretical representations of critical ecosystem functions that can be represented on an individual cell basis. A Spatial Alaskan Forest Ecosystem Dynamics (SAFED) model was developed that is based on the nitrogen productivity concept for forest growth, litter fall quality, and microbial efficiency for forest floor decomposition. Climate and ecosystem disturbances were handled as restricted stochastic processes. The restriction was based on known state-factor relationships. The state factors are used to describe a broad-scale classification of the landscape to define basic limitations for the randomly derived driving variables used in the model. The model has been programed as ARC/INFO macro language within the GRID package. The current version of the model has been verified as functional from an individual tree basis (1-m2 cell size) within an old-growth white spruce (Picea glauca (Moench) Voss) forest found in interior Alaska.

Boreal forest ecosystem dynamics. II. Application of the model to four vegetation types in interior Alaska

2000 ◽  
Vol 30 (6) ◽  
pp. 1010-1023 ◽  
Author(s):  
John Yarie
Keyword(s):  
Forest Ecosystem ◽  
Forest Floor ◽  
White Spruce ◽  
Ecosystem Dynamics ◽  
Vegetation Types ◽  
Litter Fall ◽  
Individual Tree ◽  
Balsam Poplar ◽  
Interior Alaska ◽  
Site Types

The Spatial Alaskan Forest Ecosystem Dynamics (SAFED) model was validated across four of the most common vegetation types found in interior Alaska. The vegetation types were an alder (Alnus spp.) - balsam poplar (Populus balsamifera L.) site (FP2), an old-growth balsam poplar and white spruce (Picea glauca (Moench) Voss) site (FP3), a mixed deciduous (primarily birch (Betula papyrifera Marsh.) and aspen (Populus tremuloides Michx.)) and white spruce site (UP2), and a mature white spruce site (UP3). The FP site types are common on the floodplain along the Tanana River and the UP site types are common in the uplands in interior Alaska. SAFED is based on nitrogen productivity for vegetation growth, litter fall quantity and quality, and microbial efficiency for forest floor decomposition. The state factors (climate, topography, and disturbance) are used to describe a broad-scale classification of the landscape to define basic limitations for the driving variables. Climate and ecosystem-level disturbances are handled as restricted stochastic processes. The model has been programed in a spatial framework as an ARC/INFO AML within the GRID package. The current version of the model has been validated as functional from an individual tree basis (1-m2 cell size) in a number of forest types found in interior Alaska. The growth, litter fall, and forest floor decomposition were compared with data from the sites. An estimate of yearly carbon balance for the four sites was calculated.

scholarly journals Coastal hypoxia and sediment biogeochemistry

2009 ◽  
Vol 6 (7) ◽  
pp. 1273-1293 ◽  
Author(s):  
J. J. Middelburg ◽  
L. A. Levin
Keyword(s):  
Organic Matter ◽  
Bottom Water ◽  
Water Exchange ◽  
Transport Processes ◽  
Ecosystem Dynamics ◽  
Ecosystem Functions ◽  
Oxygen Levels ◽  
Concise Review ◽  
Water Oxygen ◽  
Sediment Biogeochemistry

Abstract. The intensity, duration and frequency of coastal hypoxia (oxygen concentration <63 μM) are increasing due to human alteration of coastal ecosystems and changes in oceanographic conditions due to global warming. Here we provide a concise review of the consequences of coastal hypoxia for sediment biogeochemistry. Changes in bottom-water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways), the efficiency of re-oxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes. Hypoxia may also lead to more organic matter accumulation and burial and the organic matter eventually buried is also of higher quality, i.e. less degraded. Bottom-water oxygen levels also affect the organisms involved in organic matter processing with the contribution of metazoans decreasing as oxygen levels drop. Hypoxia has a significant effect on benthic animals with the consequences that ecosystem functions related to macrofauna such as bio-irrigation and bioturbation are significantly affected by hypoxia as well. Since many microbes and microbial-mediated biogeochemical processes depend on animal-induced transport processes (e.g. re-oxidation of particulate reduced sulphur and denitrification), there are indirect hypoxia effects on biogeochemistry via the benthos. Severe long-lasting hypoxia and anoxia may result in the accumulation of reduced compounds in sediments and elimination of macrobenthic communities with the consequences that biogeochemical properties during trajectories of decreasing and increasing oxygen may be different (hysteresis) with consequences for coastal ecosystem dynamics.

The Lake Duparquet Research and Teaching Forest: Building a foundation for ecosystem management

1999 ◽  
Vol 75 (3) ◽  
pp. 389-393 ◽  
Author(s):  
Brian Harvey
Keyword(s):  
Ecosystem Management ◽  
Forest Ecosystem ◽  
Research Program ◽  
Scientific Basis ◽  
Ecosystem Dynamics ◽  
Fire Disturbance ◽  
Research And Teaching ◽  
Research Activities ◽  
Boreal Shield ◽  
Natural Dynamics

The Lake Duparquet Research and Teaching Forest is situated in northwestern Quebec in the Boreal Shield Ecozone. Managed by two constituents of the Université du Québec, in collaboration with two forest companies, Norbord and Tembec, the Lake Duparquet Forest has a strong research program focussed on natural forest ecosystem dynamics that provides the scientific basis for management and silvicultural trials recently begun in the Forest. A bibliographical review of research activities is presented. Keywords: boreal, mixedwood, natural dynamics, fire, disturbance, ecosystem management, silviculture

scholarly journals AEROSPACE MONITORING OF THE FOREST ECOSYSTEM DYNAMICS WITHIN THE TERRITORY OF VRACHANSKI BALKAN NATURE PARK

2018 ◽  
pp. 41-46
Author(s):  
Adlin Dancheva
Keyword(s):  
Remote Sensing ◽  
Forest Ecosystem ◽  
Vegetation Index ◽  
Forest Ecosystems ◽  
Normalized Difference Vegetation Index ◽  
Remote Sensing And Gis ◽  
Ecosystem Dynamics ◽  
Anthropogenic Pressure ◽  
Water Index ◽  
Nature Park

In this paper the application of Remote Sensing and GIS as a means of performing aero – space monitoring of forest ecosystems dynamics is being considered. The purpose of this work is to create a model for monitoring the dynamic of forest ecosystems, based on Remote Sensing and GIS. The results of eco-monitoring can be used to update plans and policies for forest ecosystem management. The territory of Vrachanski Balkan Nature park was chosen as the subject of research as there is a certain anthropogenic pressure there. The results presented are obtained by spatial-time analysis of certain aerospace data indices. To carry out the study optical satellite images were used, on the basics of which three indices were calculated: Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI) and Normalized Difference Greenness Index (NDGI). A comparative analysis has been created and results of the degree of correlation between the different indices are presented, as well as indicators from the different test areas and related changes in the individual points in time. The results of the survey aim to assess the dynamics and condition of the forest vegetation on the territory of Vrachanski Balkan Nature park and can be utilised in activities related to monitoring, mapping and forest management.

scholarly journals Highly Local Model Calibration with a New GEDI LiDAR Asset on Google Earth Engine Reduces Landsat Forest Height Signal Saturation

2020 ◽  
Vol 12 (17) ◽  
pp. 2840 ◽  
Author(s):  
Sean P. Healey ◽  
Zhiqiang Yang ◽  
Noel Gorelick ◽  
Simon Ilyushchenko
Keyword(s):  
Optical Sensors ◽  
Forest Structure ◽  
Model Calibration ◽  
Google Earth ◽  
Ecosystem Dynamics ◽  
Ecosystem Functions ◽  
Calibration Data ◽  
Local Models ◽  
Google Earth Engine ◽  
Signal Saturation

While Landsat has proved to be effective for monitoring many elements of forest condition and change, the platform has well-documented limitations in measuring forest structure, the vertical distribution of the canopy. This is important because structure determines several key ecosystem functions, including: carbon storage; habitat suitability; and timber volume. Canopy structure is directly measured by LiDAR, and it should be possible to train Landsat structure models at a highly local scale with the dense, global sample of full waveform LiDAR observations collected by NASA’s Global Ecosystem Dynamics Investigation (GEDI). Local models are expected to perform better because: (a) such models may take advantage of localized correlations between structure and canopy surface reflectance; and (b) to the extent that models revert to the mean of the calibration data due to a lack of discrimination, local models will revert to a more representative mean. We tested Landsat-based relative height predictions using a new GEDI asset on Google Earth Engine, described here. Mean prediction error declined by 23% and important prediction biases at the extremes of the range of canopy height dropped as model calibration became more local, minimizing forest structure signal saturation commonly associated with Landsat and other passive optical sensors. Our results suggest that Landsat-based maps of structural variables such as height and biomass may substantially benefit from the kind of local calibration that GEDI’s dense sample of LiDAR data supports.

scholarly journals A New Tree-Ring Width, δ13C and 14C Investigation of the Two Creeks Site

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 792-797 ◽  
Author(s):  
Steven W. Leavitt ◽  
Robert M. Kalin
Keyword(s):  
Stable Carbon Isotope ◽  
Ring Width ◽  
Forest Growth ◽  
Tree Ring Width ◽  
Stable Carbon ◽  
Lake Levels ◽  
Individual Tree ◽  
Width Measurements ◽  
Cross Dating ◽  
Good Agreement

We have made isotopic and dendrochronologic measurements on material collected from the Two Creeks site. Radiocarbon dating of outside wood of four logs yielded an average age of 11,760 ± 100 BP, in good agreement with results of Broecker and Farrand (1963) over 25 years ago. The range of 11,640 ± 160 to 11,900 ± 160 BP suggests a period of forest growth of 200–300 years, consistent with a ring-width chronology established by Kaiser (1987). Ring counting of five specimens gave a range of individual tree ages from 110 to 182 years, and width measurements indicate very low year-to-year variation in ring size. However, preliminary cross-dating of five samples produced a 202-year floating chronology. Stable-carbon isotope chronologies on cellulose from five-year ring groups show δ13C scatter among trees typical of that found within modern sites, with some matches of isotopic maxima and minima. Some downward δ13C trends may result from physiological response to rising lake levels (and/or cooling temperatures) at the site, which also produced very narrow rings in the outer ca. 50 ± 20 years.

scholarly journals Using JABOWA-3 for forest growth and yield predictions under diverse forest conditions of Nova Scotia, Canada

2012 ◽  
Vol 88 (06) ◽  
pp. 708-721 ◽  
Author(s):  
M. Irfan Ashraf ◽  
Charles P.-A. Bourque ◽  
David A. MacLean ◽  
Thom Erdle ◽  
Fan-Rui Meng
Keyword(s):  
Climate Change ◽  
Nova Scotia ◽  
Model Prediction ◽  
Prediction Accuracy ◽  
Basal Area ◽  
Forest Growth ◽  
Growth And Yield ◽  
Individual Tree ◽  
Forest Conditions ◽  
Forest Growth And Yield

Empirical growth and yield models developed from historical data are commonly used in developing long-term strategic forest management plans. Use of these models rests on an assumption that there will be no future change in the tree growing environment. However, major impacts on forest growing conditions are expected to occur with climate change. As a result, there is a pressing need for tools capable of incorporating outcomes of climate change in their predictions of forest growth and yield. Process-based models have this capability and may, therefore, help to satisfy this requirement. In this paper, we evaluate the suitability of an ecological, individual-tree-based model (JABOWA-3) in generating forest growth and yield projections for diverse forest conditions across Nova Scotia, Canada. Model prediction accuracy was analyzed statistically by comparing modelled with observed basal area and merchantable volume changes for 35 permanent sample plots (PSPs) measured over periods of at least 25 years. Generally, modelled basal area and merchantable volume agreed fairly well with observed data, yielding coefficients of determination (r2) of 0.97 and 0.94 and model efficiencies (ME) of 0.96 and 0.93, respectively. A Chi-square test was performed to assess model accuracy with respect to changes in species composition. We found that 83% of species-growth trajectories based on measured basal area were adequately modelled with JABOWA-3 (P > 0.9). Model-prediction accuracy, however, was substantially reduced for those PSPs altered by some level of disturbance. In general, JABOWA-3 is much better at providing forest yield predictions, subject to the availability of suitable climatic and soil information.

scholarly journals Interregional Crown Width Models for Individual Trees Growing in Pure and Mixed Stands in Austria

Forests ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 114 ◽  
Author(s):  
Rafael Buchacher ◽  
Thomas Ledermann
Keyword(s):  
Species Composition ◽  
Predictor Variable ◽  
Forest Growth ◽  
Silver Fir ◽  
Mixed Stands ◽  
Data Set ◽  
Individual Tree ◽  
Crown Width ◽  
Site Characteristics ◽  
The Relationship

Crown width is a functional trait that is commonly used to improve the estimation of above-ground biomass of forests and is often included as a predictor variable in forest growth models. Most of the existing crown width models reflect the relationship between crown width, tree size and competition variables, but do not consider the effect of species mixture. In this study, we developed crown width models for individual-tree of the major tree species growing in Austria. Because these models should be applicable for mixed and pure stands and should also take into account the characteristics of different sites, the relationship between crown width, site variables and species composition was investigated. For that purpose, we used data from a sub-sample of the Austrian National Forest Inventory, which comprises crown width measurements of about 8900 trees from 1508 sample plots. Because of the hierarchical structure of the data set (i.e., trees nested within the plot) which destroys the independencies between observations, linear mixed-effects models were used. The species composition of the stand was included via the species-specific relative proportions of basal area. To describe the interregional variability of crown width, dummy variables were introduced, which account for region-specific differences. Site characteristics were incorporated through the altitude, slope and aspect of the site. For Norway spruce, silver fir, Scots pine, European larch, European beech, oak species and ash/maple species it was possible to develop crown width models, which reflect the effects of site characteristics and species composition of the stand. The crown widths of shade-tolerant species reacted mainly positively to admixture, whereas light-demanding species reacted with decreasing crown widths. Coniferous species were not as strongly affected by mixture as broadleaf species.

scholarly journals Long-Term Economic Simulation: Even-Aged and Uneven-Aged Examples from the Missouri Ozark Forest Ecosystem Project (MOFEP)

2005 ◽  
Vol 22 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Thomas Treiman ◽  
John Dwyer ◽  
David Larsen
Keyword(s):  
Forest Ecosystem ◽  
Landscape Management ◽  
Forest Products ◽  
Forest Growth ◽  
Economic Outcomes ◽  
Long Term Effects ◽  
Short Term ◽  
Decision Matrix ◽  
Using Data

Abstract Much of the software and many of the algorithms commonly used to simulate forest growth and harvesting activities have been optimized for short-term projections based primarily on larger-sized trees and are focused on even-aged silvicultural systems. Using data on trees 1.5 in. dbh and larger from the Missouri Ozark Forest Ecosystem Project (MOFEP), we have adapted the widely available Landscape Management System (LMS) and Forest Vegetation Simulator (FVS) software to make long-term simulations using even and uneven-aged silvicultural management systems. MOFEP is designed to test the long-term effects of even-aged, uneven-aged, and no harvest treatments on a variety of ecosystem attributes. To simulate the economic outcomes of these three treatments, we have written new LMS algorithms that simulate the effects of uneven-aged harvesting. Our results show that in the Missouri Ozarks even-aged and uneven-aged management silvicultural systems yield long-term (100 years) economic outcomes that are not statistically different. This result reinforces the need for land managers or landowners to consider esthetics, nontraditional forest products, and other nonmarket values in their decision matrix. North. J. Appl. For. 22(1):42– 47.

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