Statistische Analyse von Waldschadensdaten aus Luftbildern mit Berücksichtigung von Nachbarschaftseffekten

Quednau, H. D.

doi:10.1007/bf02741398

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…Instead, the rate of foliage loss was positively correlated with intensity of competition. This is in good agreement with Quednau (1989), who proved 'negative contagion' by completely different methods (other statistical methods used for data from remote sensing) in extremely damaged stands in Frankenwald. Our results do not exclude the possibility of a sheltering effect; we expect that the increased rate of foliage loss may be more pronounced at openings larger than those encountered in this study -despite the fast decline in our plots, there are hardly any trees there that might be considered as solitary.…”

Section: Discussionsupporting

confidence: 90%

“…This supports the hypothesis that local density promotes mortality (Peet & Christensen 1987). A similar effect was found by Quednau (1989) in severely damaged stands in Germany. Very probably the competition among neighbouring trees, which has pronounced effects on the mortality during self-thinning in natural stands, also increases the rate of defoliation and mortality caused by other stress factors.…”

Section: Discussionsupporting

confidence: 87%

“…Forest decline is studied less frequently at the population and community level; for example, opening up of the forest canopy can speed up the spread of the damage (Wolak 1981, Smith 1981; on the other hand, we have shown (Vacek & Lep‰ 1987) that suppressed trees are more susceptible to other stress factors, both natural and those caused by air pollution. Quednau (1989) demonstrated a similar effect of neighbours in damaged forests in the Frankenwald area, Germany.…”

Section: Introductionmentioning

confidence: 66%

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Spatial dynamics of forest decline: the role of neighbouring trees

Vacek¹,

Lepš²

1996

J Vegetation Science

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Abstract. Changes in horizontal structure and the influence of neighbours on tree vitality were studied in a spruce forest under air pollution stress. Five permanent plots along an altitudinal gradient in the Krkonoše Mts., Czech Republic, were monitored for 18 years. Digitized maps of each plot were used for the analysis: the health of each tree, expressed by the defoliation degree was recorded each year, the biometrical characteristics were measured at five‐year intervals. Various indices of neighbourhood competition were used to evaluate the interference with neighbours. The results show that the suppressed trees are most susceptible to other environmental stresses, particularly to the air pollution stress. Similarly, tree damage is more severe in plots near the natural timberline, where the trees are close to their natural environmental limits. The spatial pattern of surviving trees changes towards regularity at a scale of 2–5 m (K‐function analysis) when the suppressed trees, usually those with close neighbours, die.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 66%

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Spatial dynamics of forest decline: the role of neighbouring trees

Vacek¹,

Lepš²

1996

J Vegetation Science

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“…Since covariates are constant within clusters and do not contain tree{speci c information, correlations among trees of the same cluster are very likely. This has already be pointed out by Kublin (1987) and Quednau (1989). To account for that, we will apply marginal ordinal regression models developed in the next section for analyzing the data.…”

Section: Survey and Data Descriptionmentioning

confidence: 94%

Regression analysis of forest damage by marginal models for correlated ordinal responses

Fahrmeir¹,

Pritscher²

1996

Environ Ecol Stat

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Studies on forest damage can generally not be carried out by common regression models, mainly for two reasons: Firstly, the response variable, damage state of trees, is usually observed in ordered categories. Secondly, responses are often correlated, either serially, as in a longitudinal study, or spatially, as in the application of this paper, where neighborhood interactions exist between damage states of spruces determined from aerial pictures. Thus so{called marginal regression models for ordinal responses, taking into account dependence among observations, are appropriate for correct inference. To this end we extend the binary models of Liang and Zeger (1986) and develop an ordinal GEE1 model, based on parametrizing association by global cross{ratios. The methods are applied to data from a survey conducted in Southern Germany. Due to the survey design, responses must be assumed to be spatially correlated. The results show that the proposed ordinal marginal regression models provide appropriate tools for analyzing the in uence of covariates, that characterize the stand, on the damage state of spruce.

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Regionalisierung in den Geowissenschaften

Schröder¹

1994

Neuere Statistische Verfahren Und Modellbildung in Der Geoökologie

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Statistische Analyse von Waldschadensdaten aus Luftbildern mit Berücksichtigung von Nachbarschaftseffekten

Cited by 6 publications

References 11 publications

Spatial dynamics of forest decline: the role of neighbouring trees

Spatial dynamics of forest decline: the role of neighbouring trees

Regression analysis of forest damage by marginal models for correlated ordinal responses

Regionalisierung in den Geowissenschaften

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