Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatio-temporal modelling of forest monitoring data: Modelling German
  tree defoliation data collected between 1989 and 2015 for trend estimation
  and survey grid examination using GAMMs   Spatio-temporal modelling of tree defoliation data of German forest condition
survey is presented. In the present study generalized additive mixed models
were used to estimate the spatio-temporal trends of defoliation of the main
tree species from 1989 to 2015 and to examine the suitability of different
monitoring grid resolutions. Although data has been collected since 1989, this
is the first time the spatio-temporal modelling for entire Germany has been
carried out. Besides the space-time component, stand age showed a significant
effect on defoliation. The mean age and the species-specific relation between
defoliation and age determined the general level of defoliation whereas
fluctuations of defoliation were primarily related to weather conditions. The
study indicates a strong association between drought stress and defoliation of
all four main tree species. Besides direct effects of weather conditions,
indirect effects seem to play a further role. Defoliation of the comparably
drought-tolerant species pine and oak was primarily affected by insect
infestations following drought whereas considerable time for regeneration was
required by beech following drought stress and recurring substantial
fructification. South-eastern Germany has emerged as the region with the
highest defoliation since the drought year 2003. This region was characterized
by the strongest water deficits in 2003 compared to the long-term reference
period. The present study gives evidence that the focus has moved from air
pollution to climate change. Furthermore, the spatio-temporal model was used to
carry out a simulation study to compare different survey grid resolutions. This
grid examination indicated that an 8 x 8 km grid instead of the standard 16 x
16 km grid is necessary for spatio-temporal trend estimation and for detecting
hot-spots in defoliation in space and time, especially regarding oak.

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The categories of this paper are: atom-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an