35 research outputs found
Species-specific, pan-European diameter increment models based on data of 2.3 million trees
ResearchBackground: Over the last decades, many forest simulators have been developed for the forests of individual
European countries. The underlying growth models are usually based on national datasets of varying size, obtained
from National Forest Inventories or from long-term research plots. Many of these models include country- and
location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography
effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to
apply models outside the region or country they were developed for. However, there is a clear need for more
generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires
the development of models that are applicable across the European continent. The purpose of this study is to
develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We
compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest
Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil
and nutrient deposition.
Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables
was done using a combination of forward and backward selection methods. The explained variance ranged from
10% to 53% depending on the species. Variables related to forest structure (basal area of the stand and relative size
of the tree) contributed most to the explained variance, but environmental variables were important to account for
spatial patterns. The type of environmental variables included differed greatly among species.
Conclusions: The presented diameter increment models are the first of their kind that are applicable at the
European scale. This is an important step towards the development of a new generation of forest development
simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and
applicable to a wider range of management systems than before. This allows European scale but detailed analyses
concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etcinfo:eu-repo/semantics/publishedVersio
Physician-assisted death in psychiatric practice in the Netherlands
textabstractBACKGROUND: In 1994 the Dutch Supreme Court ruled that in exceptional
instances, physician-assisted suicide might be justifiable for patients
with unbearable mental suffering but no physical illness. We studied
physician-assisted suicide and euthanasia in psychiatric practice in the
Netherlands. METHODS: In 1996, we sent questionnaires to 673 Dutch
psychiatrists - about half of all such specialists in the country - and
received 552 responses from the 667 who met the study criteria (response
rate, 83 percent). We estimated the annual frequencies of requests for
physician-assisted suicide by psychiatrists and actual instances of
assistance. RESULTS: Of the respondents, 205 (37 percent) had at least
once received an explicit, persistent request for physician-assisted
suicide and 12 had complied. We estimate there are 320 requests a year in
psychiatric practice and 2 to 5 assisted suicides. Excluding those who had
ever assisted, 345 of the respondents (64 percent) thought
physician-assisted suicide because of a mental disorder could be
acceptable, including 241 who said they could conceive of instances in
which they themselves would be willing to assist. The most frequent
reasons for refusing were the belief that the patient had a treatable
mental disorder, opposition to assisted suicide in principle, and doubt
that the suffering was unbearable or hopeless. Most, but not all, patients
who had been assisted by their psychiatrists in suicide had both a mental
disorder and a serious physical illness, often in a terminal phase. Thirty
percent of the respondents had been consulted at least once by a physician
in another specialty about a patient's request for assisted death. The
annual number of such consultations was estimated at 310, about 3 percent
of the estimated 9700 requests for euthanasia or physician-assisted
suicide in medical practice. CONCLUSIONS: Explicit requests for
physician-assisted suicide are not uncommon in psychiatric practice in the
Netherlands, but these requests are rarely granted. Psychiatric
consultation for medical patients who request physician-assisted death is
relatively rare