Abstract
Abstract This review attempts to assess the causal factors and their interrelations that cause decline of widespread European oak ( Quercus ) species. In particular, it provides an overview of recent advances in cause-effect research since 2000. The first recorded outbreak of oak decline took place in 1739-1748, and was followed by several other decline episodes, most of them occurring in the twentieth century. The mortality rates differ substantially among the European regions and decline episodes; however, the decline of entire stands is a rare event. The principal causes of oak decline are the following site-unspecific factors: severe (in particular, repeated) defoliation by insect larvae, especially in combination with infection by powdery mildew and weather extremes (summer drought, winter frost and spring frost); and the following site-specific factors: the root pathogen Phytophthora quercina (which is virulent in soils with a pH[CaCl 2 ] value ≥3.5 and certain fractions of exchangeable calcium), and a distinct decrease in the groundwater level. At hydromorphic sites, intermittent soil moisture can intensify the impact of drought. At least in the temperate regions, two or more of these factors have to act in combination to cause major outbreaks of decline. Other biotic factors such as the root pathogen Collybia fusipes and the borers Agrilus biguttatus or Platypus cylindrus can contribute to the damage in later stages of decline. In the Mediterranean region, the aggressive root pathogen Phytophthora cinnamomi as well as prolonged periods of intense drought probably are capable of causing oak decline without any contribution of additional factors. Other possible causal factors, whose importance still has to be corroborated, are the decrease in chemical defence compounds against leaf herbivores due to eutrophication with nitrogen, and increased ozone concentrations.
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Claims 16
Claim · model-written summary
Repeated defoliation by insect larvae, especially combined with powdery mildew infection and weather extremes, is a principal site-unspecific cause of oak decline.
- Interactor
- insect larvaee2herbivore
- Second interactor
- powdery mildewe2pathogen
- Outcome
- oak declinee2
- Qualifier
- site-unspecific factorse2
QuercusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e2“The principal causes of oak decline are the following site-unspecific factors: severe (in particular, repeated) defoliation by insect larvae, especially in combination with infection by powdery mildew and weather extremes (summer drought, winter frost and spring frost)”
Claim · model-written summary
The root pathogen Phytophthora quercina, virulent in soils with a pH[CaCl 2] value of at least 3.5 and certain exchangeable calcium fractions, is a principal site-specific cause of oak decline.
- Interactor
- Phytophthora quercinaPhytophthora quercinae3pathogen
- Outcome
- declinee1
- Qualifier
- virulent in soils with a pH[CaCl 2 ] value ≥3.5 and certain fractions of exchangeable calciume3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e3“the following site-specific factors: the root pathogen Phytophthora quercina (which is virulent in soils with a pH[CaCl 2 ] value ≥3.5 and certain fractions of exchangeable calcium)”
Claim · model-written summary
A distinct decrease in groundwater level is a site-specific factor of oak decline.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e4“and a distinct decrease in the groundwater level”
Claim · model-written summary
The root pathogen Collybia fusipes can contribute to the damage in later stages of oak decline.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e5“Other biotic factors such as the root pathogen Collybia fusipes and the borers Agrilus biguttatus or Platypus cylindrus can contribute to the damage in later stages of decline”
Claim · model-written summary
The borer Agrilus biguttatus can contribute to the damage in later stages of oak decline.
- Interactor
- Agrilus biguttatus
Agrilus biguttatuse5pest - Outcome
- damagee5
- Qualifier
- in later stages of declinee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e5“Other biotic factors such as the root pathogen Collybia fusipes and the borers Agrilus biguttatus or Platypus cylindrus can contribute to the damage in later stages of decline”
Claim · model-written summary
The borer Platypus cylindrus can contribute to the damage in later stages of oak decline.
- Interactor
- Platypus cylindrus
_(14771005797).png?width=60)
Platypus cylindruse5pest - Outcome
- damagee5
- Qualifier
- in later stages of declinee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_(14771005797).png?width=500)
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e5“Other biotic factors such as the root pathogen Collybia fusipes and the borers Agrilus biguttatus or Platypus cylindrus can contribute to the damage in later stages of decline”
Claim · model-written summary
In the Mediterranean region, Phytophthora cinnamomi is probably capable of causing oak decline without any contribution of additional factors.
- Interactor
- Phytophthora cinnamomi
Phytophthora cinnamomie6pathogen - Outcome
- oak declinee6
- Qualifier
- without any contribution of additional factorse6
- Setting
- Mediterranean regione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e6“In the Mediterranean region, the aggressive root pathogen Phytophthora cinnamomi as well as prolonged periods of intense drought probably are capable of causing oak decline without any contribution of additional factors”
Claim · model-written summary
In the Mediterranean region, prolonged periods of intense drought are probably capable of causing oak decline without any contribution of additional factors.
- Treatment
- prolonged periods of intense droughte6
- Outcome
- oak declinee6
- Qualifier
- without any contribution of additional factorse6
- Setting
- Mediterranean regione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e6“In the Mediterranean region, the aggressive root pathogen Phytophthora cinnamomi as well as prolonged periods of intense drought probably are capable of causing oak decline without any contribution of additional factors”
Claim · model-written summary
Decrease in chemical defence compounds against leaf herbivores due to nitrogen eutrophication is a possible causal factor of oak decline that still has to be corroborated.
- Treatment
- eutrophication with nitrogene7
- Interactor
- leaf herbivorese7herbivore
- Compound
- chemical defence compoundse7
- Outcome
- declinee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e7“Other possible causal factors, whose importance still has to be corroborated, are the decrease in chemical defence compounds against leaf herbivores due to eutrophication with nitrogen”
Claim · model-written summary
Increased ozone concentrations are a possible causal factor of oak decline that still has to be corroborated.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e2“and increased ozone concentrations”
Claim · model-written summary
At least in temperate regions, two or more of the site-unspecific and site-specific factors must act in combination to cause major outbreaks of oak decline.
- Outcome
- major outbreaks of declinee2
- Qualifier
- two or more of these factors have to act in combinatione2
- Setting
- temperate regionse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e2“At least in the temperate regions, two or more of these factors have to act in combination to cause major outbreaks of decline”
Claim · model-written summary
At hydromorphic sites, intermittent soil moisture can intensify the impact of drought on oak.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e2“At hydromorphic sites, intermittent soil moisture can intensify the impact of drought”
Claim · model-written summary
Oak mortality rates differ substantially among European regions and decline episodes.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e2“The mortality rates differ substantially among the European regions and decline episodes”
Claim · model-written summary
Decline of entire oak stands is a rare event.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e3“however, the decline of entire stands is a rare event”
Claim · model-written summary
The first recorded outbreak of oak decline took place in 1739-1748.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e3“The first recorded outbreak of oak decline took place in 1739-1748, and was followed by several other decline episodes, most of them occurring in the twentieth century”
Claim · model-written summary
Most oak decline episodes occurred in the twentieth century.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“cause decline of widespread European oak ( Quercus ) species”
e3“The first recorded outbreak of oak decline took place in 1739-1748, and was followed by several other decline episodes, most of them occurring in the twentieth century”