Search

The demand for wood in Europe is expected to increase in the coming decades. However, any theoretical maximum supply will be affected by sustainability constraints, the motivations of forest owners and regional factors, such as incentives, species and assortments. However, the influence of these factors on supply is changeable. In this study, we quantify what might be realistically available as additional wood supply from currently existing European forests, based on a combination of results of the forest resource model EFISCEN-Space and a literature review of national supply projections. Wood mobilization scenarios for 10 representative Model Regions in Europe that assume forest owners and managers in the simulated regions will adapt their behaviour to alternative behaviour as recorded from other regions were projected with the EFISCEN-Space model. The realistic additional potential based on the literature review is 90 million m3 yr−1. This potential should be attainable within 10–20 years. However, the simulations in the Model Regions found potentials to be lower in 7 out of 10 cases as compared with the country they are located in. On average, the model regions reached less than half of the potential as compared with the literature review. This suggests that the realistic additional potential at the European scale may well be lower if all mobilization barriers are taken into account in more detail, but also highlights the uncertainty surrounding these estimates. We conclude from the analyses that although there are large differences in potential between regions and the analysis method employed, there are no ‘hotspots’ where a large pool of accessible wood can be quickly mobilized using existing infrastructure for nearby industries. An increase in harvest would therefore only be possible with a large effort that spans the whole chain, from forest owners’ behaviour to capacity building, financial incentives and matching resources to harvesting capacity. The additionally available wood can most likely only be mobilized against higher marginal costs and will thus only become available in times of higher stumpage prices. The largest potential lies in privately owned forests which often have a fragmented ownership but will most likely be able to supply more wood, though mostly from deciduous species. In the long term (more than 20 years), additional wood, compared with the amounts we found for short term, can only be made available through investments in afforestation, forest restoration, improved forest management and more efficient use of raw material and recycled material.

This study develops some components to complete a management-oriented dynamic model system for simulating current and future volume and biomass of even-aged stands of managed downy birch (Betula pubescens Ehrh.) in Galicia (NW Spain). The specific components developed are a mortality equation, a basal area growth equation, a diameter distribution prediction system and equations for total and component biomass prediction. Functions to predict decreases in numberof trees per hectare and basal area growth were simultaneously fitted using Nonlinear Seemingly Unrelated Regression (NSUR) and a base-age invariant dummy variable method; critical errors of 19 and 16 per cent were obtained, respectively, when projections were made. The Weibull function modelled successfully all but four of the 198 diameter distributions examined, using the parameter recovery method through moments. To predict components and total aboveground biomass, a system of additive equations was simultaneously fitted using the generalized method of moments (GMM), which takes into account heteroscedasticity and inherent correlations among the biomass components. A two-step fitting procedure was used because of the different number of observations for the components considered. The biomass equations explained more than 85 per cent of the observed variability. The Galician birch stands which were surveyed were found to have grown by 3–10 m ha year in volume and by 2–8 Mg ha year in aboveground total biomass, with rotations between 30 and 60 years. The model system now forms an accessible decision support system for forest management and land development in the region.

The most common form of forest stand parameter estimation is undertaken based on field-based forest inventory data. Parameter estimations are implemented at a range of scales depending on the user needs and requirements. Due to time and cost constraints, these approaches are sample based, with measurements collected using sampling frames, which tend to be sparsely distributed when inventories are carried out across a country (e.g. national forest inventories) or region (Matthews and Mackie, 2006). Commonly, forest managers require detailed information on individual stands in order to plan silvicultural management strategies. Such information is typically derived from a stand-based inventory, where detailed measurements from several plots are collected within each stand, providing more precise forest parameter estimates. In recent decades, forest practitioners have increasingly integrated remote sensing data as a means of assisting and complementing forest inventories. Aerial photography has been used extensively to estimate forest attributes, which include species identification, tree height, crown diameter and the delineation of forest boundaries (Tuominen and Pekkarinen, 2005). Top height is an important forest parameter that is used in the UK and Ireland to estimate Yield Class (annual production potential) and as an indicator of standing biomass. Using remote sensing, tree height can be measured using high-resolution stereoscopic aerial photos, with photogrammetric techniques to measure the lengths of shadows projected onto level open ground (Kovats, 1997). However, these techniques are dependent on a number of factors that include level open ground and the need to determine the sun elevation and latitude, which consequently limits the operational use of these techniques. However, a more effective approach to determine tree heights in forests is by using parallax measurements from stereoscopic photographs (Schut and Van Wijk, 1965). More recently, research has been conducted that combines space-borne satellite imagery with forest inventory Forest canopy height retrieval using LiDAR data, medium-resolution satellite imagery and kNN estimation in Aberfoyle, Scotland

We assessed age-related alterations in carbon (C) stocks and sequestration rates of first rotation Sitka spruce (Picea sitchensis (Bong.) Carr) plantations on predominantly surface-water gley soils. Sites were selected to represent a typical Sitka spruce chronosequence following land use transition from grasslands dominated by surface-water gley soils. Based on inventory, eddy covariance, physiological and modelling assessments of net ecosystem productivity (NEP), we show that afforested stands are a C sink at 10 years, and possibly earlier, followed by an increase to a maximum of 9 t C ha−1 year−1 before the first thinning cycle. NEP subsequently declined from 9 t C ha−1 year−1, at closed canopy, to 2 t C ha−1 year−1 in older and thinned stands. Reductions in the C sequestration rate of older stands were coupled with a decrease in gross primary productivity, increases in maintenance/growth respiration and decomposition losses following harvest. We suggest that the high sequestration potential of these forests may be associated with the high net primary productivity of these plantations in Ireland, a high allocation of assimilates and litter into the belowground C pool and accumulation of C in mineral gley soils following afforestation.

Summary The requirement for reporting of changes in forest carbon (C) stocks under the United Nations Framework Convention on Climate Change and to the Kyoto Protocol has underlined a need for information on the deadwood pool. As the coarse woody debris (CWD) component of the deadwood pool falls outside the remit of most C-stock change models used in reporting processes, this study set out to develop a methodology to evaluate the C-content of CWD stocks in the main Irish forest type (Sitka spruce plantations). In order to calculate CWD stocks without information on thinning/harvesting dates, the development of a system of classifying CWD into fi ve decay classes (DCs) is presented. DCs were based mainly on visual characteristics linked to the degree of decomposition. Samples were taken from thinned fi rst rotation plantations to establish the basic density loss associated with each DC. Stocks, including logs, stumps and roots, ranged from 5.1 to 13.1 t C ha − 1 in forests aged 30 and 33 years, respectively. Decay rates for both stump and log material were 0.0592 and 0.0466 g cm − 3 a − 1 , respectively.

Summary The relationship between leaf area and diameter at breast height (d.b.h.) or sapwood area (AS) has been used to estimate stand leaf area or biomass of forest canopies. It has been suggested that intra-specifi c variations in the relationship between stand leaf area and d.b.h. or AS can introduce a systematic error in these estimates for younger and older stands unless additional parameters relating to canopy structure are included in allometric functions. We collected data from a Sitka spruce chronosequence to parametrize and test different algorithms for the estimation of foliar biomass (FB) and litter inputs over a range of forest ages. FB estimates were signifi cantly improved when additional biometric information relating to crown structure (canopy openness and height of live crown) was included in the models. Although the use of the relationship between leaf area and AS for the estimation of leaf area is justifi ed by theoretical considerations (pipe model theory), we show that d.b.h. and other canopy parameters provided the most robust estimation of leaf area across different-aged stands. Our results also suggest that the accuracy of litter input estimates depends on needle retention time and annual turnover rate, particularly immediately before and after canopy closure.

Summary The research reported in this article, carried out in the period 1995‐1997, was part of a large-scale project investigating the impact of soil cultivation/drainage practices upon water-table depth, rooting depth, root architecture and biomass production of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees on surface water gley soils. On two sites in the mid-west of Ireland, a total of 207 trees, 5 and 7 years old, were excavated over a 2-year period, during which water-table depths were monitored. Results showed that neither mound drains nor mole drains had as great an effect on tree rooting depth as the presence of a planting mound. In the cultivation treatments that included planting on mounds, tree roots were mainly confined within the mounds, with the exception of the tree root systems in the mole-and-mound treatment on one of the sites, where the mean root depth of both the 5-year-old and 7-year-old trees reached almost 20 cm below the original soil level. Continued evaluation of these experiments is required to assess the long-term effectiveness of the different drainage and cultivation methods in increasing rooting depth and improving tree stability.

Summary This article reports on a study initiated to assess in detail the volume and value recovery losses associated with damage resulting from a 1998 catastrophic storm in Ireland. The results are based on a 0.39 ha representative site in Swanlinbar forest, County Cavan. Detailed analysis showed that the loss in recovery in the broken stems amounted to a volume loss of 27 per cent with an associated value loss of 29 per cent. On a stand basis this corresponded to 13.4 per cent of stems broken, resulting in a 2.6 per cent volume loss. The value loss of IR£0.87 per cubic metre recovered amounted to IR£310.94/ha or 2.8 per cent of the potential revenue. During the milling of the blown timber, no additional loss was incurred as a result of log defects resulting from storm damage. A significant relationship between diameter at breast height (d.b.h.) and the occurrence of breakage was established, with the smaller diameter trees more likely to snap than those with larger d.b.h. measurements. No significant relationship between the location of the breakage along the stem and the d.b.h. of the trees was found.

Birch in Ireland has long been regarded a timber species of minor importance, and it is noted more often for its invasiveness in young coniferous forests and clearfelled areas than for its potential as a commercial forestry species. While research on other native hardwood species such as oak or ash has been ongoing for a number of years, very little is known about the Irish birch resource. The lack of quantitative data relating to height growth, diameter growth and volume increment of birch in this country is of particular concern. The objective of this study was to examine the growth potential of birch in Ireland. Following a field survey, eight well-stocked, unthinned birch stands were selected for inclusion in the study. All of the selected stands were determined to be downy birch. Following analysis of sample tree disc sections, two stands were excluded (because of indistinct annual rings) and the study was restricted to the six remaining stands. A total of 100 sample trees were felled at the six sites. Tree ring data were collected from a total of 1333 sample tree disc sections. Using these ring data, the historic patterns of radial growth at breast height, height growth and volume growth of the six stands were reconstructed, examined and analysed in detail. The results showed that for well-stocked, unthinned, even-aged stands the period of maximum radial growth, and therefore diameter growth, occurred between the ages of 5 and 20 years. The fastest growing tree achieved a diameter of 25 cm in 32 years. It is suggested that for the stands included in this study, the lack of management, in particular the lack of adequate thinning, will have resulted in excessive crown competition and consequently reduced diameter growth. Maximum height increment occurred before the age of 20 years and fast growing trees achieved a height growth of >1 m per year during this period. The results showed that a well-stocked, unthinned downy birch stand can achieve a standing volume (under-bark) of 200 m 3 ha - 1 in 42 years. While some of the stands included in the study had not reached the age of maximum mean annual increment, comparison with the Forestry Commission yield models showed that stands of downy birch in Ireland can achieve a yield class of 8 and, given the correct thinning regime, total recovered volume production could possibly be raised to that equivalent with yield class 10.

The climate in Ireland is oceanic and windy. An occasional feature of this climate is the occurrence of storms, which cause damage to forests on a catastrophic scale. Such storms can cause substantial economic losses. On 24 December l997 a major storm caused extensive damage to forests in the south of Ireland. Maximum gusts of 101 m.p.h. were recorded in Valentia, 92 m.p.h. at Cork Airport and 94 m.p.h. at Rosslare. The exceptional feature of the storm was the high mean wind speeds recorded. Average wind speeds over 10-min periods of 69, 64 and 54 m.p.h. were recorded for Valentia, Cork Airport and Rosslare, respectively. The damage was almost exclusively concentrated in Counties Cork, Kerry and Waterford, with minor wind blows occurring in Counties Limerick and Wicklow (Anon., l998). Survey results suggested that trees with a combined Financial impact evaluation of catastrophic storm damage in Irish forestry: a case study. I. Stumpage losses