Forest disturbance dynamics

Course Approach, assessment

- Website: forestdisturbancecourse.weebly.com

– 5 lectures:• Case studies

• Literature

• 2 ECTS

– Excursion

– Course assignment:• Essay

Lectures by topic

Lecture 1 – Introduction/Wind 05 November – Jeroen Engelhart

Lecture 2 – Fire/Beaver12 November – Floor Vodde

Lecture 3 – Herbivores: ungulates19 November – Marek Metslaid

Lecture 4 – Pathogens and insects 26 November – Tiia Drenkhan

Lecture 5 – Excursion: Halliku03 December – Jeroen Engelhart

Lecture 6 – Interactions of disturbances, human interference, climate change, future perspectives10 December – Kalev Jõgiste, Floor Vodde

Encourage all interested to register: vaike.reisner@emu.ee or floortje.vodde@emu.ee

Course assignment

• Essay (topic of own interest within forest disturbances)

– Write a ‘scientific introduction/background’ to:• a research proposal OR

• a scientific publication

– Lead to one or two hypotheses for testing

– Requirements • 500-1000 words

• Minimum of 2 references

• By end of January

• Estimated workload for the assignment: 8 hours

Course assignment

• Essay examples:1. The potential of remote sensing to detect forest areas disturbed by pathogens

2. Forest disturbance: Moose (Alces alces) and its impact on boreal forest

3. Use of shepherding to maintain firewalls in southern Europe

4. Detecting disturbance events in Scots pine stands with the boundary-line method

5. Influence of increase in disturbance regimes on biodiversity levels of temperate forests in Western Europe

• Take articles as an example

Course assignment

• Kneeshaw D.D., Williams H., Nikinmaa E., Messier C. 2002. Patterns of above- and below-ground response of understory conifer release 6 years after partial cutting. Canadian Journal of Forest

Research 32: 255-265

• The introduction >> a relatively broad to a more specific context, about theresponse of understory trees after release.

• This is followed by 3 general statements or scenarios (in this paper also calledhypotheses) of this response, heavily supported by literature.

• Then the objectives of the study are presented.

• In the end these objectives are followed up with an overall hypothesis.

• The introduction does give a good basis for the research with thorough objectives and hypotheses, but the mixing up decreases its strength >>

context – objectives- hypotheses

‘Disturbance’ (Seidl et al 2011)

“any discrete event in time that disrupts ecosystem structure, composition and/or processes

by altering its physical environment and/or resources,

causing destruction of plant biomass’’(synthesized from White and Pickett, 1985; Gunderson, 2000; Grime, 2001; White and

Jentsch, 2001)”

Lecture 1 – Introduction to the course - Wind

Disturbance

• Abiotic vs. biotic

• Exogene (outside) vs. endogene (inside)

• Allogenic (external to stand level and are often large in extent, e.g. disturbance

caused by fire and storms) vs. autogenic (caused by biotic factors within

stands (tree deaths caused by fungi, insects, and competition)

Components (disturbance descriptors)?

• Size (spatial scale)

• Magnitude: intensity (e.g. physical force of wind or heat of fire) +

severity (=actual damage done)

• Frequency

Lecture 1 – Introduction to the course - Wind

Distinctions between discrete events

Factors characterizing disturbances such as their abruptness, duration and magnitude are considered relative to ecosystem properties and their characteristic time scales.

“Discrete” thus implies that a disturbance does not necessarily occur instantaneously, but rapidly relative to the change in the system’s state variables that would occur in the absence of disturbance. (Seidl et al 2011)

Lecture 1 – Introduction to the course - Wind

Discrete events/disturbances

Lecture 1 – Introduction to the course - Wind

Succession

Ecological succession is the process of change in the species structure of an ecological community over time. (wiki)

A conceptual model of the basic processes and factors creating and maintaining heterogeneity and biodiversity within a forested area. Biodiversity is maintained by the interplay between the available range of species and their life-history characteristics, and the dynamic heterogeneity of forest structure created by disturbances and successional processes (Kuuluvainen 2002)

Concepts• Succession• Disturbance• Disturbance

regimes• Disturbance

legacies

Lecture 1 – Introduction to the course - Wind

Heterogeneity & Biodiversity

In broad terms, the concept of heterogeneity can be defined as any form of environmental variation, physical or biotic, occurring in space and/or time(Ostfeld et al. 1997).