Improving tree mortality models by accounting for environmental influences

2007 ◽  
Vol 37 (11) ◽  
pp. 2106-2114 ◽  
Author(s):  
Henrik Hartmann ◽  
Christian Messier ◽  
Marilou Beaudet
Keyword(s):  
Tree Mortality ◽  
External Validation ◽  
Growth Patterns ◽  
External Factors ◽  
Model Parameters ◽  
Similar Frequency ◽  
Growth Series ◽  
Recent Growth ◽  
Dead Trees ◽  
The Impact

Tree-ring chronologies have been widely used in studies of tree mortality where variables of recent growth act as an indicator of tree physiological vigour. Comparing recent radial growth of live and dead trees thus allows estimating probabilities of tree mortality. Sampling of mature dead trees usually provides death-year distributions that may span over years or decades. Recent growth of dead trees (prior to death) is then computed during a number of periods, whereas recent growth (prior to sampling) for live trees is computed for identical periods. Because recent growth of live and dead trees is then computed for different periods, external factors such as disturbance or climate may influence growth rates and, thus, mortality probability estimations. To counteract this problem, we propose the truncating of live-growth series to obtain similar frequency distributions of the “last year of growth” for the populations of live and dead trees. In this paper, we use different growth scenarios from several tree species, from several geographic sources, and from trees with different growth patterns to evaluate the impact of truncating on predictor variables and their selection in logistic regression analysis. Also, we assess the ability of the resulting models to accurately predict the status of trees through internal and external validation. Our results suggest that the truncating of live-growth series helps decrease the influence of external factors on growth comparisons. By doing so, it reinforces the growth–vigour link of the mortality model and enhances the model’s accuracy as well as its general applicability. Hence, if model parameters are to be integrated in simulation models of greater geographical extent, truncating may be used to increase model robustness.

Growth-dependent tree mortality models based on tree rings

2003 ◽  
Vol 33 (2) ◽  
pp. 210-221 ◽  
Author(s):  
Christof Bigler ◽  
Harald Bugmann
Keyword(s):  
Norway Spruce ◽  
Tree Mortality ◽  
Time Windows ◽  
Growth Patterns ◽  
Linear Regression Models ◽  
Growth Trends ◽  
Mortality Model ◽  
Recent Growth ◽  
Mortality Models ◽  
The Impact

Mortality is a crucial element of population dynamics. However, tree mortality is not well understood, particularly at the individual level. The objectives of this study were to (i) determine growth patterns (growth levels and growth trends) over different time windows that can be used to discriminate between dead and living Norway spruce (Picea abies (L.) Karst.) trees, (ii) optimize the selection of growth variables in logistic mortality models, and (iii) assess the impact of competition on recent growth in linear regression models. The logistic mortality model that we developed for mature stands classified an average of nearly 80% of the 119 trees from one site correctly as being dead or alive. While more than 50% of the variability of recent growth of living trees can be attributed to the influence of competition, this percentage was only 25% for standing dead trees. The predictive power of the logistic mortality model was validated successfully at two additional sites, where 29 of 41 (71%) and 34 of 42 (81%) trees were classified correctly, respectively. This supports the generality of the mortality model for Norway spruce in subalpine forests of the Alps. We conclude that growth trends in addition to the commonly used growth level significantly improve the prediction of growth-dependent tree mortality of Norway spruce.

The relationship between tree growth patterns and likelihood of mortality: a study of two tree species in the Sierra Nevada

2007 ◽  
Vol 37 (3) ◽  
pp. 580-597 ◽  
Author(s):  
Adrian J. Das ◽  
John J. Battles ◽  
Nathan L. Stephenson ◽  
Phillip J. van Mantgem
Keyword(s):  
Sierra Nevada ◽  
Mortality Risk ◽  
External Validation ◽  
Model Development ◽  
Logistic Models ◽  
Growth Patterns ◽  
Growth Trend ◽  
Average Growth ◽  
Dead Trees ◽  
Sugar Pine

We examined mortality of Abies concolor (Gord. & Glend.) Lindl. (white fir) and Pinus lambertiana Dougl. (sugar pine) by developing logistic models using three growth indices obtained from tree rings: average growth, growth trend, and count of abrupt growth declines. For P. lambertiana, models with average growth, growth trend, and count of abrupt declines improved overall prediction (78.6% dead trees correctly classified, 83.7% live trees correctly classified) compared with a model with average recent growth alone (69.6% dead trees correctly classified, 67.3% live trees correctly classified). For A. concolor, counts of abrupt declines and longer time intervals improved overall classification (trees with DBH ≥20 cm: 78.9% dead trees correctly classified and 76.7% live trees correctly classified vs. 64.9% dead trees correctly classified and 77.9% live trees correctly classified; trees with DBH <20 cm: 71.6% dead trees correctly classified and 71.0% live trees correctly classified vs. 67.2% dead trees correctly classified and 66.7% live trees correctly classified). In general, count of abrupt declines improved live-tree classification. External validation of A. concolor models showed that they functioned well at stands not used in model development, and the development of size-specific models demonstrated important differences in mortality risk between understory and canopy trees. Population-level mortality-risk models were developed for A. concolor and generated realistic mortality rates at two sites. Our results support the contention that a more comprehensive use of the growth record yields a more robust assessment of mortality risk.

scholarly journals Stock of standing dead trees in boreal forests of Central Siberia

2021 ◽  
Vol 875 (1) ◽  
pp. 012059
Author(s):  
L V Mukhortova ◽  
L V Krivobokov ◽  
D G Schepaschenko ◽  
A A Knorre ◽  
D S Sobachkin
Keyword(s):  
Boreal Forests ◽  
Tree Mortality ◽  
Forest Ecosystems ◽  
Middle Taiga ◽  
Central Siberia ◽  
Dead Trees ◽  
Larch Forests ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
The Impact

Abstract A significant part of carbon assimilated by forest is deposited in tree trunks. Growth and development of tree stands is accompanied by accumulation of standing dead trees (snags) due to natural tree mortality and as a result of the impact of exogenous factors. Carbon accumulated in these dead trunks is excluded from the fast turnover due to low rate of wood decomposition, so that snags can be considered as a pool of organic carbon with a slow rate of its return to the atmosphere. We estimated stock of snags on 54 sample plots, which represent the main types of forest ecosystems in the northern and middle taiga of Central Siberia. In the middle taiga, stock of snags varied from up to 7 m3 ha-1 in Siberian spruce forests to 20-42 m3 ha-1 in Scots pine forests. Larch forests in the northern taiga had the similar stock of snags as larch forests in the middle taiga despite significantly higher growing stock in the later. Snags contributed from 4 to 19% to the total stock of woody biomass in studied forests. This study indicated the significance of snags and can be used to estimate carbon budget of forest ecosystems of the region.

Short-term impact of a spruce budworm outbreak on a deer wintering area

1980 ◽  
Vol 10 (4) ◽  
pp. 559-563 ◽  
Author(s):  
François Potvin
Keyword(s):  
Large Scale ◽  
Tree Mortality ◽  
Balsam Fir ◽  
Short Term ◽  
Deer Population ◽  
Dead Trees ◽  
Spruce Stands ◽  
Wintering Areas ◽  
Wintering Area ◽  
The Impact

The impact of the current budworm outbreak on deer (Odocoileusvirginianusborealis Miller) was studied from 1972 to 1979 in a wintering area located at the northern extremity of Témiscouata Lake, Québec. This area encompassed 20 km2 and consisted mostly of balsam fir (Abiesbalsamea (L.) Mill.) and spruce (Piceaglauca (Moench) Voss) stands which suffered high mortality in 1975. The proportion of coniferous cover dropped from 66 to 29% as a result of the outbreak. Nevertheless, the area occupied by deer and the deer population itself remained quite stable. Deer progressively deserted balsam fir - spruce stands and sought shelter in cedar (Thujaoccidentalis L.) stands that are well distributed throughout the study area. Elimination of balsam fir from the shrub layer of the more severely affected stands resulted in a loss of two-thirds of the browse biomass and invasion by raspberry (Rubusidaeus L.). Conversely, tree lichens on dead trees have become an important new food source. The impact of large-scale tree mortality by the budworm in wintering areas sharing the same ecological conditions may depend on the presence or absence of cedar stands as an alternative coniferous cover type.

Differential impacts of calcium and aluminum treatments on sugar maple and American beech growth dynamics

2015 ◽  
Vol 45 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Joshua M. Halman ◽  
Paul G. Schaberg ◽  
Gary J. Hawley ◽  
Christopher F. Hansen ◽  
Timothy J. Fahey
Keyword(s):  
Sugar Maple ◽  
Tree Mortality ◽  
Growth Dynamics ◽  
Growth Patterns ◽  
Forest Composition ◽  
Ice Storm ◽  
Al Tolerance ◽  
Annual Increment ◽  
American Beech ◽  
The Impact

Acid deposition induced losses of calcium (Ca) from northeastern forests have had negative effects on forest health for decades, including the mobilization of potentially phytotoxic aluminum (Al) from soils. To evaluate the impact of changes in Ca and Al availability on sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifolia Ehrh.) growth and forest composition following a major ice storm in 1998, we measured xylem annual increment, foliar cation concentrations, American beech root sprouting, and tree mortality at the Hubbard Brook Experimental Forest (Thornton, New Hampshire) in control plots and in plots amended with Ca or Al (treated plots) beginning in 1995. Dominant sugar maple trees were unaffected by the treatment, but nondominant sugar maple tree growth responded positively to Ca treatment. Although plots were mainly composed of sugar maple, American beech experienced the greatest growth on Al-treated plots. Increases in tree mortality on Al-treated plots may have released surviving American beech and increased their growth. The Al tolerance of American beech and the Ca:Al sensitivity of sugar maple contributed to divergent growth patterns that influenced stand productivity and composition. Given that acidic inputs are expected to continue, the growth dynamics associated with Al treatment may have direct relevance to future conditions in native forests.

scholarly journals The impact of leaf-eating caterpillars (Heortia vitessoides) infestation on agar trees in Carita forest research station, Province of Banten

2018 ◽  
Vol 7 (1) ◽  
pp. 25
Author(s):  
Kuntadi Kuntadi ◽  
Ragil S.B. Irianto
Keyword(s):  
Tree Mortality ◽  
Research Station ◽  
Monitoring And Control ◽  
Forest Research ◽  
Tree Plantation ◽  
Monthly Basis ◽  
Tree Defoliation ◽  
Dead Trees ◽  
Periodic Monitoring ◽  
The Impact

The gregarious caterpillars of Heortia vitessoides Moore is a major defoliator of agar trees. The pest seriously threatens the existing agar tree plantation that has been widely cultivated in the community. Pest attacks began to occur in Indonesia since 2005, resulting in the damage and death of agar tree plants in various regions.To determine the impact of pest attack, a study was conducted through periodic monitoring at agar plantation in Carita Forest Research Station (CFRS), Banten Province, from April 2012 to March 2015. Monitoring was conducted in three plots of agar plantations. Each plot consists of six permanent subplots and in each subplot 15 samples of agar tree were randomly choosen. Data were collected and analyzed on monthly basis according to the intensity of defoliation and the mortality of agar trees. Defoliation intensity was determined by the percentage number of trees suffering defoliation in four damage categories, i.e.: light (10-25%), moderate (25-50%), heavy (50-75%), and severe (75-100%). Tree mortality was calculated as the annual percentage of dead trees. The study showed that the defoliation occurred throughout the year in varying degrees of damage. The monthly percentage of defoliated trees is about 30-70% annualy. The high percentage of tree defoliation mainly occurs during dry and early rainy season (June-December). Higher percentage of heavy and severe defoliations were found mostly at seedling. Repeated heavy defoliation causes stunted growth and tree mortality. Early monitoring and control of pests are very important to be done regularly to prevent the damage wider and heavier.

Assessing drought-induced mortality of European beech and Scots pine in the Valais, Switzerland

2021 ◽  
Author(s):  
Sabine Rothenbühler ◽  
Lorenz Walthert ◽  
Matthias Saurer ◽  
Holger Gärtner ◽  
Arthur Gessler ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Tree Rings ◽  
Tree Mortality ◽  
Leaf Gas Exchange ◽  
Stem Growth ◽  
Growth Patterns ◽  
Carbon And Oxygen Isotopes ◽  
Climate Conditions ◽  
Dead Trees ◽  
Recent Climate

&lt;p&gt;Tree mortality due to climate change and particularly drought is a globally observed issue and has been studied widely. However, the underlying physiological mechanisms are still not fully understood. One approach to assess the drivers of drought-induced mortality is to retrospectively investigate predisposing factors that have led to tree death by utilizing tree rings. Here we combine annual stem growth, and stable carbon and oxygen isotopes (&amp;#120575;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#120575;&lt;sup&gt;18&lt;/sup&gt;O) in tree rings of recently died and living trees of two species, drought tolerant Pinus sylvestris and drought sensitive Fagus sylvatica, in the Rhone Valley (Valais), the driest part of Switzerland.&lt;/p&gt;&lt;p&gt;Irrespective of specific drought tolerance, growth patterns of now-dead and living trees were significantly different in both species. Now-dead trees showed higher growth rates than living trees, for at least half of their life span. In the last two decades this pattern was reversed and growth of now-dead trees was at a lower level compared to living trees. In this recent time period, &amp;#120575;&lt;sup&gt;18&lt;/sup&gt;O records of now-dead trees of both species showed a distinct decrease, while no systematic difference was found in the tree-ring &amp;#120575;&lt;sup&gt;13&lt;/sup&gt;C records of now-dead and living trees. Climate correlation analysis revealed that stem growth of now-dead trees was more sensitive to climate compared to living trees and that the relationship between isotope-derived leaf gas exchange and climate weakened in the late period prior to death.&lt;/p&gt;&lt;p&gt;Our findings suggest that now-dead trees followed a more conservative water-use strategy in their declining phase. Decreasing &amp;#160;values and weakened relationships to climate indicate a reduction in stomatal conductance, accompanied by reduced photosynthetic activity, since the ratio of photosynthesis to stomatal conductance remained unchanged. Overall, our results suggest a combination of hydraulic failure and carbon starvation as initiators of tree death at our study sites, probably in different stages of tree life. It is obvious that recent climate conditions already strongly affected the trees, such that in a future environment negative effects will most likely increase.&lt;/p&gt;

scholarly journals Background mortality drivers of European tree species: climate change matters

2019 ◽  
Vol 286 (1900) ◽  
pp. 20190386 ◽  
Author(s):  
Adrien Taccoen ◽  
Christian Piedallu ◽  
Ingrid Seynave ◽  
Vincent Perez ◽  
Anne Gégout-Petit ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Species ◽  
Tree Mortality ◽  
Forest Tree ◽  
Climate Change Signal ◽  
Dead Trees ◽  
Background Mortality ◽  
Increasing Temperature ◽  
The Impact ◽  
Stand Characteristics

Increases in tree mortality rates have been highlighted in different biomes over the past decades. However, disentangling the effects of climate change on the temporal increase in tree mortality from those of management and forest dynamics remains a challenge. Using a modelling approach taking tree and stand characteristics into account, we sought to evaluate the impact of climate change on background mortality for the most common European tree species. We focused on background mortality, which is the mortality observed in a stand in the absence of abrupt disturbances, to avoid confusion with mortality events unrelated to long-term changes in temperature and rainfall. We studied 372 974 trees including 7312 dead trees from forest inventory data surveyed across France between 2009 and 2015. Factors related to competition, stand characteristics, management intensity, and site conditions were the expected preponderant drivers of mortality. Taking these main drivers into account, we detected a climate change signal on 45% of the 43 studied species, explaining an average 6% of the total modelled mortality. For 18 out of the 19 species sensitive to climate change, we evidenced greater mortality with increasing temperature or decreasing rainfall. By quantifying the mortality excess linked to the current climate change for European temperate forest tree species, we provide new insights into forest vulnerability that will prove useful for adapting forest management to future conditions.

Estimating OLED Display Device Lifetime from pixel and screen brightness and its application

2019 ◽  
Vol 2019 (1) ◽  
pp. 331-338 ◽  
Author(s):  
Jérémie Gerhardt ◽  
Michael E. Miller ◽  
Hyunjin Yoo ◽  
Tara Akhavan
Keyword(s):  
Image Processing ◽  
Power Consumption ◽  
Model Parameters ◽  
Display Device ◽  
Image Processing Algorithm ◽  
Pixel Value ◽  
Device Lifetime ◽  
The Impact ◽  
Oled Display

In this paper we discuss a model to estimate the power consumption and lifetime (LT) of an OLED display based on its pixel value and the brightness setting of the screen (scbr). This model is used to illustrate the effect of OLED aging on display color characteristics. Model parameters are based on power consumption measurement of a given display for a number of pixel and scbr combinations. OLED LT is often given for the most stressful display operating situation, i.e. white image at maximum scbr, but having the ability to predict the LT for other configurations can be meaningful to estimate the impact and quality of new image processing algorithms. After explaining our model we present a use case to illustrate how we use it to evaluate the impact of an image processing algorithm for brightness adaptation.

Some reflections on social structure: Theoretical and practical aspects

2020 ◽  
Vol 18 (6) ◽  
pp. 1063-1078
Author(s):  
T.N. Skorobogatova ◽  
I.Yu. Marakhovskaya
Keyword(s):  
Service Industry ◽  
External Factors ◽  
Infrastructure Development ◽  
Social Infrastructure ◽  
Social Sphere ◽  
The Social ◽  
Study Results ◽  
The Republic ◽  
Internal And External Factors ◽  
The Impact

Subject. This article discusses the role of social infrastructure in the national economy and analyzes the relationship between the notions of Infrastructure, Service Industry and Non-Productive Sphere. Objectives. The article aims to outline a methodology for development of the social infrastructure of Russia's regions. Methods. For the study, we used the methods of statistical and comparative analyses. The Republic of Crimea and Rostov Oblast's social infrastructure development was considered as a case study. Results. The article finds that the level of social infrastructure is determined by a number of internal and external factors. By analyzing and assessing such factors, it is possible to develop promising areas for the social sphere advancement. Conclusions. Assessment and analysis of internal factors largely determined by the region's characteristics, as well as a comprehensive consideration of the impact of external factors will help ensure the competitiveness of the region's economy.

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