Workpackage 3 -Impacts of Disturbance
Team
- Prof Maarten Nieuwenhuis
- Dr Brian Tobin
- Mr Thomas Turpin-Jelfs
Background
The CARBWARE system, used for reporting and accounting forest carbon stock changes, is dependent on the input of accurate and verifiable activity data.
This work package outlines a need for research to identify and quantify the impacts on forest carbon stocks of disturbances.
These disturbances can arise from forest management activities, as well as from biotic (e.g. disease or pest outbreaks) and abiotic
(e.g. snow, fire or wind damage) factors, and cause changes in productivity of forest carbon stocks and flows between forest carbon pools.
The primary aims for the Workpackage are as follows:
- To identify the impact of disturbance on the pools of forest deadwood carbon;
- To quantify the fate of the deadwood carbon pools following a disturbance.
Work Plan
For the purposes of this investigation a distinction has been drawn between planned disturbances (e.g. management related), and unplanned disturbances:
Planned disturbance
Task3.1 Forest Management
- Harvest residue;
- Clearfell and thinning residue;
- Decomposition changes.
- Windrowing/Cultivation;
- Residue harvesting for energy;
- Alternative management systems.
Unplanned disturbance
Task 3.1. Forest management
Disturbances in forest ecosystems arising from management activities are often poorly quantified in the short-term by normal inventory methodologies,
as well as the inbuilt assumptions of reporting mechanisms. Thus the following factors will be explored to assess the reliability of existing systems
and to develop new processes to improve the reporting capacity:
- Harvest residue
- Quantification of clearfell and thinning residue
Coillte, a commercial company operating in forestry, currently employ an algorithm based on species and tree volume to estimate the quantity of merchantable
timber volume which will remain on-site after thinning and clearfelling activities have occurred. However, the assumptions contained within this algorithm will
require validation if they are to underpin reporting figures. Thus data collated from existing sources will be used to assess the integrity of this reporting
mechanism and to further develop it to account for harvest residues, such as brash, stumps and belowground root systems.
- Decomposition changes
Clearfelling affects the microclimatic conditions of the forest floor as a result of reductions in forest canopy cover. This is significant as changes in these
conditions can cause increases in the rates of decomposition of deadwood nutrient stores, such as course woody debris, fine woody debris and litter. Therefore
the impacts of increased decomposition rates will be assessed by comparing data from localised environments against the CARBiFOR II database, as well as by changes
in on-site stocks.
- Windrowing
Windrowing is a management practice which is used to clear a site for replanting whilst retaining fertility after it has been harvested. Furthermore, it provides
a microsite shelter for newly planted stock. Stumps may be included in windrowing; however, the effects of the proportions of stumps included upon the rate of
decomposition are largely unknown. Thus existing NFI and Coillte data will be analysed to quantify the impacts of stump inclusion and where this data is not
available a series of surveys will be carried out at representative sites.
Additionally, Coillte and private forest data will be used to identify forest management preference regarding the scheduling of fallow periods and the extent of
windrowing operations as their timing can have a large bearing on the physical breakup of the deadwood material.
Windrows clearly visable (running vertically in picture) 5 years following reforestation at a forest in Co. Laois.
- Residue harvesting for energy
Although lagging behind the UK, the demand for harvest residue as an energy source in Ireland is experiencing an increase. Thus this task aims to identify suitable
sampling sites to quantify the proportion of the deadwood carbon pool which remains after this additional harvesting has taken place. This data may then be used to
verify the accuracy of algorithms adapted to quantify this activity.
- Alternative management systems
In Ireland, the majority of forest stands are managed using the clearfell system. However, an increasing number of forestry companies, such as Coillte, and private
forest owners are beginning to adopt Continuous Cover Forestry, a low-impact silvicultural system which has minimal negative impacts upon a forest crop and its
environment. Therefore this task will examine the effects of a conversion from clearfelling techniques to low-impact silvicultural techniques, such as Continuous
Cover Forestry, on the deadwood carbon pool.
Task 3.2. Forest fires
Reports indicate that damage rates to Coillte managed forest as a result of fire were significantly greater during the month of May in 2010 and 2011 than the
annual amounts recorded for the previous decade. Furthermore it is expected that predicted changes in the Irish climate will cause an increase in the risk and
frequency of more intense fires occurring domestically.
The sampling strategies employed by NFI to monitor the stock changes associated with management and natural disturbances are insufficient to accurately characterise
fire events. Thus a study will be carried out to determine where fires occur using EU spatial products in conjunction with Coillte data and to establish what
consequences this disturbance type has upon stock losses and survival, subsequent management strategies and the deadwood carbon pool. This investigation will be
used to contribute to a possible further development of the residue algorithm in Task 3.1. of Work Package 3.
Planned disturbance
- Harvest residue;
- Clearfell and thinning residue;
- Decomposition changes.
- Windrowing/Cultivation;
- Residue harvesting for energy;
- Alternative management systems.
- Task3.1 Forest Management
Task 3.1. Forest management
Disturbances in forest ecosystems arising from management activities are often poorly quantified in the short-term by normal inventory methodologies,
as well as the inbuilt assumptions of reporting mechanisms. Thus the following factors will be explored to assess the reliability of existing systems
and to develop new processes to improve the reporting capacity:
- Harvest residue
- Quantification of clearfell and thinning residue
Coillte, a commercial company operating in forestry, currently employ an algorithm based on species and tree volume to estimate the quantity of merchantable
timber volume which will remain on-site after thinning and clearfelling activities have occurred. However, the assumptions contained within this algorithm will
require validation if they are to underpin reporting figures. Thus data collated from existing sources will be used to assess the integrity of this reporting
mechanism and to further develop it to account for harvest residues, such as brash, stumps and belowground root systems.
- Decomposition changes
Clearfelling affects the microclimatic conditions of the forest floor as a result of reductions in forest canopy cover. This is significant as changes in these
conditions can cause increases in the rates of decomposition of deadwood nutrient stores, such as course woody debris, fine woody debris and litter. Therefore
the impacts of increased decomposition rates will be assessed by comparing data from localised environments against the CARBiFOR II database, as well as by changes
in on-site stocks.
- Windrowing
Windrowing is a management practice which is used to clear a site for replanting whilst retaining fertility after it has been harvested. Furthermore, it provides
a microsite shelter for newly planted stock. Stumps may be included in windrowing; however, the effects of the proportions of stumps included upon the rate of
decomposition are largely unknown. Thus existing NFI and Coillte data will be analysed to quantify the impacts of stump inclusion and where this data is not
available a series of surveys will be carried out at representative sites.
Additionally, Coillte and private forest data will be used to identify forest management preference regarding the scheduling of fallow periods and the extent of
windrowing operations as their timing can have a large bearing on the physical breakup of the deadwood material.
Windrows clearly visable (running vertically in picture) 5 years following reforestation at a forest in Co. Laois.
- Residue harvesting for energy
Although lagging behind the UK, the demand for harvest residue as an energy source in Ireland is experiencing an increase. Thus this task aims to identify suitable
sampling sites to quantify the proportion of the deadwood carbon pool which remains after this additional harvesting has taken place. This data may then be used to
verify the accuracy of algorithms adapted to quantify this activity.
- Alternative management systems
In Ireland, the majority of forest stands are managed using the clearfell system. However, an increasing number of forestry companies, such as Coillte, and private
forest owners are beginning to adopt Continuous Cover Forestry, a low-impact silvicultural system which has minimal negative impacts upon a forest crop and its
environment. Therefore this task will examine the effects of a conversion from clearfelling techniques to low-impact silvicultural techniques, such as Continuous
Cover Forestry, on the deadwood carbon pool.
Task 3.2. Forest fires
Reports indicate that damage rates to Coillte managed forest as a result of fire were significantly greater during the month of May in 2010 and 2011 than the
annual amounts recorded for the previous decade. Furthermore it is expected that predicted changes in the Irish climate will cause an increase in the risk and
frequency of more intense fires occurring domestically.
The sampling strategies employed by NFI to monitor the stock changes associated with management and natural disturbances are insufficient to accurately characterise
fire events. Thus a study will be carried out to determine where fires occur using EU spatial products in conjunction with Coillte data and to establish what
consequences this disturbance type has upon stock losses and survival, subsequent management strategies and the deadwood carbon pool. This investigation will be
used to contribute to a possible further development of the residue algorithm in Task 3.1. of Work Package 3.
- Quantification of clearfell and thinning residue
Coillte, a commercial company operating in forestry, currently employ an algorithm based on species and tree volume to estimate the quantity of merchantable timber volume which will remain on-site after thinning and clearfelling activities have occurred. However, the assumptions contained within this algorithm will require validation if they are to underpin reporting figures. Thus data collated from existing sources will be used to assess the integrity of this reporting mechanism and to further develop it to account for harvest residues, such as brash, stumps and belowground root systems. - Decomposition changes
Clearfelling affects the microclimatic conditions of the forest floor as a result of reductions in forest canopy cover. This is significant as changes in these conditions can cause increases in the rates of decomposition of deadwood nutrient stores, such as course woody debris, fine woody debris and litter. Therefore the impacts of increased decomposition rates will be assessed by comparing data from localised environments against the CARBiFOR II database, as well as by changes in on-site stocks.
Additionally, Coillte and private forest data will be used to identify forest management preference regarding the scheduling of fallow periods and the extent of windrowing operations as their timing can have a large bearing on the physical breakup of the deadwood material.
Windrows clearly visable (running vertically in picture) 5 years following reforestation at a forest in Co. Laois.
Reports indicate that damage rates to Coillte managed forest as a result of fire were significantly greater during the month of May in 2010 and 2011 than the
annual amounts recorded for the previous decade. Furthermore it is expected that predicted changes in the Irish climate will cause an increase in the risk and
frequency of more intense fires occurring domestically.The sampling strategies employed by NFI to monitor the stock changes associated with management and natural disturbances are insufficient to accurately characterise fire events. Thus a study will be carried out to determine where fires occur using EU spatial products in conjunction with Coillte data and to establish what consequences this disturbance type has upon stock losses and survival, subsequent management strategies and the deadwood carbon pool. This investigation will be used to contribute to a possible further development of the residue algorithm in Task 3.1. of Work Package 3.
The remains of a forest stand which burnt approximately 10 years ago in Cloosh, Co. Galway.
Task 3.3. Windblow
The quantity of harvest residue at a managed site is largely dependent upon the forest species being exploited, forest productivity and the management system
employed. However, windblow has the potential to cause an increase in the amount of residue left on-site. The extent of this increase can be attributed to the type
of windblow and how soon after a windlblow event a stand is harvested. Thus data regarding windblown forest areas, the time at which windlow residue is harvested and
the quantities of deadwood/residue remaining after harvesting will be collated from sources such as NFI and Coillte to inform a common management practice and to
produce a windblow residue estimate that can be used to develop a specialised residue algorithm for use with CARBWARE.
Task 3.4. Deforestation
Felling licences, which are issued by the Forest Service under Forestry Act 1946, require harvested areas to be immediately reforested to ensure sustainable forest
management. However, exemptions to this condition may be permitted in some instances which can lead to a transition in land-use as a result of deforestation. This
is of concern because it has yet to be identified how land-use transitions may impact upon the fate of the deadwood carbon pools. CARBWARE currently relies upon
unverified data to account for transition events and thus an investigation will be implemented to determine the fate of harvest residue in land-use transitions
from forestry to developments such as grasslands, wetlands, settlements and windfarms to improve reporting capacity.
Felling licences, which are issued by the Forest Service under Forestry Act 1946, require harvested areas to be immediately reforested to ensure sustainable forest
management. However, exemptions to this condition may be permitted in some instances which can lead to a transition in land-use as a result of deforestation. This
is of concern because it has yet to be identified how land-use transitions may impact upon the fate of the deadwood carbon pools. CARBWARE currently relies upon
unverified data to account for transition events and thus an investigation will be implemented to determine the fate of harvest residue in land-use transitions
from forestry to developments such as grasslands, wetlands, settlements and windfarms to improve reporting capacity.
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