Showing papers in "Forestry in 2001"
TL;DR: White-tailed deer have increased in abundance and expanded their geographic range in North America over the past century, and now exist at higher densities than they have in the past several hundred years, having numerous impacts on the forest ecosystems they inhabit.
Abstract: Summary White-tailed deer have increased in abundance and expanded their geographic range in North America over the past century, and now exist at higher densities than they have in the past several hundred years. This is having numerous impacts on the forest ecosystems they inhabit. Regional recruitment failure of eastern hemlock (Tsuga canadensis) and northern white cedar (Thuja occidentalis) trees can be explained in part by deer browsing. Deer also have significant negative effects on understorey plants, including wild lily-of-the-valley (Maianthemum canadense) and whiteflowered trillium (Trillium grandiflorum). Long-term studies of primary, old-growth forest stands reveal a 48‐81 per cent herb and shrub species loss accompanying increases in deer density. Graminoids, ferns and club mosses were more likely to persist in these stands than plants in all other taxonomic groups. Deer also exhibit indirect effects on forest communities by reducing host plant densities or altering forest structure. Because of their numerous direct and indirect effects on other species, and because of the magnitude of these effects, white-tailed deer act as a keystone herbivore. Natural regulation and maximum sustained yield management approaches have failed to alleviate deer impacts on forest ecosystems, but an ecosystem-based management approach offers promise.
392 citations
TL;DR: The results show that deer tend to reduce the diversity of seedlings, and that the effect is greater at higher deer densities, which appears to depend on site characteristics, including the light regime and composition of the ground vegetation.
Abstract: Summary The effect of deer on woodland vegetation is reviewed, focusing on processes that are likely to bring about changes in structure and composition. By browsing on tree seedlings, shrubs and climbers, deer tend to reduce stem densities, limit height growth and reduce foliage density, creating a more open understorey. Light penetration to the ground can be increased, providing more plant cover close to the ground surface. Using results from 13 studies in temperate woodlands, the effects of deer browsing on the species richness and diversity of trees were analysed using general linear models. The results show that deer tend to reduce the diversity of seedlings, and that the effect is greater at higher deer densities. Differences in susceptibility of tree species were evident, with some species being depleted by deer at all sites, whereas others declined in some sites but increased in others. The effects of deer on the amount and composition of regeneration appear to depend on site characteristics, including the light regime and composition of the ground vegetation. Although few studies of seed dispersal by ungulates (endozoochory) have been made in Britain, deer have been shown to be effective seed dispersers of a number of plant species. Plants with small hard seeds are most likely to survive digestion. Most of the species known to be dispersed in this way include grasses and small herbs. In view of the fact that dispersal mechanisms of many woodland species are not well understood, endozoochory may be more important than is generally realized.
336 citations
TL;DR: This paper summarizes the main issues that emerged from papers presented at a meeting on 'Ecological Impacts of Deer in Lowland Woods' in April 2000, and suggests convincing reasons to believe that for a wide range of taxa, abundances of particular species and overall community composition can be strongly modified by increasing numbers of deer.
Abstract: In recent decades, serious impacts on woodland regeneration have become widespread in Britain as a consequence of increasing numbers of deer. Concern has also been growing about possible effects of deer on the wider ecology of woodland. In April 2000, the Forest Ecology Group of the British Ecological Society held a meeting on 'Ecological Impacts of Deer in Lowland Woods'. This paper summarizes the main issues that emerged from papers presented at that meeting, several of which are published in this special issue of Forestry. The probable causes of the increases in deer populations and the problems posed for deer management are briefly considered. There are convincing reasons to believe that for a wide range of taxa, abundances of particular species and overall community composition can be strongly modified by increasing numbers of deer. Such ecological changes are probably well advanced in many British woods as a result of recent intensified grazing. The general effect of sustained heavy grazing and browsing is a reduction in the richness of biological communities. There are, however, considerable differences among species in their responses and heavy grazing is not detrimental to all species. Responses of many species will be non-linear, with intermediate levels of deer pressure being beneficial in many cases. Ecologists have an important role to play in gaining a better understanding of these effects; this is essential if informed decisions are to be made about deer management at both local and regional levels. However, such research presents many methodological challenges.
257 citations
TL;DR: Strategies are discussed for controlling the damage and wound decay in a forest, emphasizing silvicultural options for care of a stand during selective harvesting and wound treatment with appropriate dressings.
Abstract: Summary The damage caused to temperate forests by forestry operations is examined by a review of the scientific literature. A significant proportion of the remaining trees, especially in older stands, can be damaged during mechanized selective logging in forests, when operations are carried out in summer. Damage is most often caused during transport of timber. Most of the resulting wounds occur near the base of the tree and are up to 200 cm 2 in size. Damage to roots has negative effects on tree growth. Wounds on trees are attacked by fungi, causing stain and decay. In most tree species, the spread of wound decay is extensive and devalues several metres of the butt log. Wound closure is usually too slow to have any significant effect on the incidence of wound infections, but in several tree species it may restrict the spread of decay. The financial losses in wood value at the final harvest, due to previous logging damage, are reported to be significant. Strategies are discussed for controlling the damage and wound decay in a forest, emphasizing silvicultural options for care of a stand during selective harvesting and wound treatment with appropriate dressings.
157 citations
144 citations
TL;DR: Recent studies have shown that the ground flora is being heavily affected by increased levels of grazing within British broadleaved woodland, particularly as a consequence of rising deer populations.
Abstract: Summary Recent studies have shown that the ground flora is being heavily affected by increased levels of grazing within British broadleaved woodland, particularly as a consequence of rising deer populations General trends observed include a reduction in Rubus fruticosus and other tall-growing herbs and ferns (other than bracken, Pteridium aquilinum) and increases in grasses and lowergrowing species Grazing of the flowers is common for some species and may be as significant in terms of long-term survival of the species as loss of leaf material Most vegetation types contain some species that may be sensitive to grazing: their abundance will therefore be very dependent on the grazing history of the stand This can affect how the wood is classified under the National Vegetation Classification Grazing impacts must be recognized by forest managers, but are not necessarily damaging in themselves A variable and varying level of grazing within a wood is likely to bring most benefits for biodiversity
144 citations
TL;DR: Direct and indirect impacts of deer on invertebrates in lowland deciduous woodland are reviewed with particular reference to Britain and emphasis is placed on the importance of a multi-trophic approach in future studies of how deer interact with other components of the woodland ecosystem.
Abstract: Direct and indirect impacts of deer on invertebrates in lowland deciduous woodland are reviewed with particular reference to Britain. The evidence overwhelmingly indicates that deer grazing and browsing can have a very profound impact throughout the woodland ecosystem, including on invertebrates. Under certain circumstances, deer may be regarded as direct competitors with insect herbivores for plant biomass. However, more usually impacts will be indirect and mediated through changes in the structure, species composition and quality of the vegetation. The capacity of deer browsing activities to alter radically the species composition of the vegetation will have a major effect on the associated community of herbivorous insects. Whilst excessive deer densities will have detrimental effects on woodland biodiversity, including invertebrates, by inhibiting regeneration and removal of the understorey, some browsing will help to create and maintain open areas within woodland and arrest succession in rides and clearings. This will be beneficial for thermophilous insect species and those that require flowers for nectar and pollen. Evidence on how invertebrates respond to the regrowth foliage that is produced after deer damage remains equivocal but is an important question for future research. Deer also have a direct effect on the dung-associated invertebrate fauna that, in turn, provides an important food source at critical times of year for certain bird and bat species. Emphasis is placed on the importance of a multi-trophic approach in future studies of how deer interact with other components of the woodland ecosystem.
143 citations
TL;DR: The possible impacts of increased deer populations on small mammal ecology in British lowland woodlands are reviewed and a significant reduction in bank vole numbers is suggested to be the result of observed changes in the woodland vegetation.
Abstract: Summary The possible impacts of increased deer populations on small mammal ecology in British lowland woodlands are reviewed. These impacts occur mainly through two pathways. First, by the modification or removal of habitat which influences food supply, cover and the balance of competition between the species. Secondly, through direct competition for resources, particularly food supplies. Losses of woodland ground vegetation may provoke major changes in small mammal community structure which, in the extreme, may decrease from five to eight species, or more, to just wood mice (Apodemus sylvaticus). Reduction of understorey species such as hazel (Corylus avellana) or loss of shrub diversity, would be expected to lead to declines in yellow-necked mice (Apodemus flavicollis) and common dormice (Muscardinus avellanarius). Reduction of early succession mixed scrub and grassland may reduce colonization by shrews, harvest mice (Micromys minutus) and field voles (Microtus agrestis), although in woodland rides, field voles may benefit from preferential grazing of grasses by deer. Impacts on regeneration which may delay or inhibit canopy/understorey closure may encourage the ground and shrub vegetation and so favour species with a preference for ground cover such as the bank vole (Clethrionomys glareolus). Reductions in the availability of foods (e.g. mast crops) may reduce the potential for high population densities, particularly of bank voles, wood mice and yellow-necked mice, decrease the lengths of breeding seasons, and further affect community structure. If rodent densities are lowered, avian and terrestrial predators are likely to suffer reduced breeding success and tawny owls (Strix aluco) may prey more heavily on bank voles if their favoured ground cover is reduced. Studies at Wytham Woods, near Oxford, from 1949 to 1999, indicate that a significant reduction in bank vole, but not wood mouse, numbers has occurred; this is suggested to be the result of observed changes in the woodland vegetation, including a significant reduction in the ground cover of bramble (Rubus fruticosus agg.). Deer, as well as increased canopy shading, are probably the major factors causing this change in habitat and small mammal density.
118 citations
TL;DR: Regression equations of root system biomass on diameter at breast height derived from other studies might be useful for applications in forestry and as a simple input variable for growth models.
Abstract: Summary Estimates of tree root system biomass are important to understanding the dynamics of forest systems and tree growth. The difficult and time-consuming extraction of woody roots is often a limiting factor when estimating the below-stump biomass. Regression equations of root system biomass on diameter at breast height derived from other studies might be useful for applications in forestry and as a simple input variable for growth models. Data for developing regression equations and, where possible, equations were taken from the recent literature for Picea abies, Pseudotsuga menziesii, Pinus sylvestris, Pinus radiata, Pinus taeda, Fagus sylvatica, Quercus ilex and Quercus douglasii. The equation for Quercus petraea was developed using data from European research projects.
91 citations
TL;DR: In this article, site index curves and an edaphic discriminant rule for Scots pine stands in the High Ebro Basin (northern Spain) are presented to estimate site index under different silvicultural situations.
Abstract: Summary Site index curves and an edaphic discriminant rule for Scots pine stands in the High Ebro Basin (northern Spain) are presented to estimate site index under different silvicultural situations. Highgrading practices strongly modify the forestry structure by the means of bias in the dominant height and stand density. In order to achieve the silvicultural and site variability of Scots pine stands in the studied area, 75 plots from the National Forest Inventory of Spain (NFI) were selected. In these plots 46 dominant trees were cut down and 104 trees were bored at stump and at breast height (1.3 m). In each plot a soil sample from the first 10 cm of soil was taken and signs of dimensional cutting were recorded. Site index curves and the edaphic discriminant rule were developed. The site index curve model used is an extension of the Richards model. The site factors selected in the discriminant rule represent the most important edaphic parameters for forest productivity (texture and the assimilability of the nutrients). Site quality of the studied stands was medium-low as compared with other site index curves for Scots pine around the world. The edaphic discriminant rule presented is useful for estimating site index classes in stands exposed to dimensional cutting and in young stands of Scots pine in the the High Ebro Basin (northern Spain). Site index curves were fitted to allow an estimate of the site index of undisturbed and stands which were not high-graded.
65 citations
TL;DR: Above-ground leaf biomass, leaf litterfall, leaf weight loss due to decomposition, redistribution of leaf litter and C and N return to the soil, and seasonal leaf nutrient dynamics have been studied in the Sierra de la Demanda, Spain, a Mediterranean climatic zone.
Abstract: Summary Above-ground leaf biomass, leaf litterfall, leaf weight loss due to decomposition, redistribution of leaf litter and C and N return to the soil, and seasonal leaf nutrient dynamics have been studied in the Sierra de la Demanda, Spain, a Mediterranean climatic zone. The tree species considered were a climax beechwood (Fagus sylvatica L.) at ‘Tres aguas’ and planted Scots pine (Pinus sylvestris L.) at ‘La Rasada’. The above-ground biomass was estimated by cutting and weighing seven trees from each site according to their diameter classes, recording the categories of trunk, branches and leaves. The carbon and nitrogen contents in the different fractions were also analysed. The calculated total biomass ranged from 132.7 Mg ha ‐1 in the beech stand to 152.1 Mg ha ‐1 in the pine stand, and leaf biomass from 3.4 Mg ha ‐1 to 7.0 Mg ha ‐1 in the beech and pine, respectively. The C : N (carbon : nitrogen) ratio was greater in the pine forest leaves. The total litterfall was 5791 kg ha ‐1 per year in the pine forest and 4682 kg ha‐1 per year and the leaf litterfall was 2917 kg ha‐1 per year and 2897 kg ha‐1 per year in the pine and beech sites, respectively. The annual mean amount of N returning to the soil substrate was 29.9 kg ha‐1 per year on the beech and 23.3 kg ha‐1 per year on the pine. Weight loss of leaf litter due to decomposition was monitored for 2 years in the two forest ecosytems studied. The results indicated that weight loss was similar at the end of the experimental period in the two forest stands: 40 per cent in beech and 43 per cent in pine. Jenny’s decomposition index (K) and Olson’s decomposition index (KO) were higher for the pine stand than for the beech stand. The dynamics of total C and N throughout the study period was similar on both experimental plots. The evolution of N in green leaves follows the same pattern in beech and pine stands. The highest leaf N concentration was observed in the spring and summer months, during initial leaf growth. Thereafter, it decreased due to retranslocation during the period of leaf-fall in autumn.
TL;DR: Testing exclosure experiments in the summer of 1997 showed that forbs tended to increase inside exclosures whilst decreasing in the wider wood, supporting the hypothesis that deer herbivory was responsible for the change.
Abstract: Summary Between 1974 and 1992 there were declines in bramble (Rubus fruticosus agg.) and several woodland forbs and an increase in grasses at Wytham Woods. These changes have been explained as effects of increasing deer populations. We set out to test this by establishing exclosure experiments in the summer of 1997. Comparison of permanent vegetation monitoring plots inside and outside the exclosures, showed that forbs tended to increase inside exclosures whilst decreasing in the wider wood, supporting the hypothesis that deer herbivory was responsible for the change. Changes in individual species were not, however, significant and it may take many years for the vegetation in the exclosures to reach a new equilibrium. In contrast to exclosures under the woodland canopy, additional exclosures in a clearing have been rapidly colonized by bramble. It appears there is an interaction between solar radiation and herbivory and the decline of bramble at Wytham may reflect canopy closure as well as deer herbivory. Faecal pellet counts made in Environmental Change Network monitoring plots between August 1998 and April 1999 indicated different habitat use by fallow (Dama dama) and muntjac (Muntiacus reevesi) deer. Grasslands in proximity to the woodland tended to accumulate proportionally more fallow deer faeces, whilst dense ancient woodland areas tended to accumulate more muntjac faeces. There was, however, little evidence of an association between particular species of plant and differential habitat use by deer.
TL;DR: In this paper, a field survey of 33 Forestry Commission sites was made in order to collect data on attractive features at each site and these data were supplemented with variables to indicate the availability of competing woodlands and population totals within set travel distances.
Abstract: Summary Previous models to describe the desire for recreation at English forest sites have tended to use fairly crude and regional measures. This study demonstrates how forest recreation demand can be modelled quite locally and using just site-specific characteristics or simple measures of available population as input. A field survey of 33 Forestry Commission sites was made in order to collect data on attractive features at each site. These data were supplemented with variables to indicate the availability of competing woodlands and population totals within set travel distances. The outputs were simple but robust stand-alone functions to describe visits across many sites.
TL;DR: The impacts of deer on woodland butterflies: the good, the bad and the complex is described.
Abstract: Whilst many invertebrates depend on mature woodland and high forest, a number of others rely on the early successional stages within woodlands or woodland edges for their survival. Nearly three-quarters of Britain’s resident species of butterfly regularly breed in woodland, and about one-third are found exclusively or primarily in woods through much of their British range (Warren and Key, 1991). Of these true woodland butterflies, around half are strongly associated with early successional habitats within woodlands. They include several species which are either rare or rapidly declining, such as the high brown fritillary (Argynnis adippe), the pearlbordered fritillary (Boloria euphrosyne), and the heath fritillary (Mellicta athalia), all of which are listed as priority species in the UK Biodiversity Action Plan Steering Group Report (Anon., The impacts of deer on woodland butterflies: the good, the bad and the complex
TL;DR: A progressive loss of P and Mg in the decomposing oak leaves and pine needles, and a sharp loss of K were observed: in contrast, a tendency to retain N and Ca was seen, which indicates that climate (semi-arid conditions) speeds decomposition in the short term.
Abstract: Summary The production of litter, the weight loss dynamic of forest litter decomposition, and the dynamics of bioelement loss during leaf litter decomposition were determined in three forest ecosystems located in a semi-arid zone of the Duero basin, Province of Zamora, Spain, over 2 years. The three ecosystems were a climax evergreen oak (Quercus rotundifolia Lam.) woodland, a paraclimax stone pine (Pinus pinea L.) forest, and a disclimax maritime pine (Pinus pinaster Sol.) forest. The mean total production of litter in the oak forest was 2320 kg ha ‐1 year ‐1 , quite similar to the P. pinea pine forest, at 2400 kg ha ‐1 year ‐1 and higher than that of the P. pinaster pine forest at 1728 kg ha ‐1 year ‐1 . Leaves and needles accounted for most of this total production (78, 89 and 96 per cent, respectively). No significant differences were found among the different leaf decomposition processes, except for the oak leaves introduced in the pine ecosystems. A relationship between time (independent variable) and the remaining leaf weight was found, which followed a negative exponential curve, DM (dry matter) = A + B exp(‐Ct). About 30 per cent of the weight was lost during the first 4 months. This indicates that climate (semi-arid conditions) speeds decomposition in the short term. The decomposition indices were determined for leaves only and for total litter. Considering total litter and leaves separately, several relations were established for K, Ko and Kd decomposition indices. K and Ko in natural conditions decrease in the following order: evergreen oak > stone pine > maritime pine. The Q. rotundifolia woodland potentially returns a greater amount of N and Ca than both Pinus forests. A litter-bag method was used for the determination of the dynamics of the decomposing leaves. A progressive loss of P and Mg in the decomposing oak leaves and pine needles, and a sharp loss of K were observed: in contrast, a tendency to retain N and Ca was also seen. Pinus pinaster forest had the lowest annual N and P returns.
TL;DR: In this article, the authors developed a wind-throw risk model for Ireland which would yield estimates of the probability of wind-throwing for a combination of site and silvicultural factors, including top height, the regional location of the stand, the soil type on which the stand was established, as well as the compass bearing of the plough ribbons where the site had been ploughed.
Abstract: Summary Damage to trees by strong winds is one of the most important abiotic hazards in forestry in Ireland. A number of classification systems have been developed to assess the risk of wind damage to forests in Ireland and Great Britain. However, these models have tended to be deterministic, ranking the relative risk on different sites and/or from silvicultural treatments but not assigning a probability to the likelihood of damage. The main objective of the study described in this paper was to devise a windthrow risk model for Ireland which would yield estimates of the probability of windthrow for a combination of site and silvicultural factors. Data were collected for a range of Sitka spruce (Picea sitchensis (Bong.) Carr.) stands growing on a variety of sites. These stands were selected in two regions of varying exposure. The modelling procedure examined the relationship between a range of site and silvicultural factors and the occurrence of windthrow. Out of the 15 factors examined, the following five were shown to contribute significantly to the risk of windthrow: top height, the regional location of the stand, the soil type on which the stand was established, as well as the compass bearing of the plough ribbons where the site had been ploughed. Whether or not the stand had been thinned was also important.
TL;DR: It is suggested that for Sitka spruce stumps on wet sites, the risk of successful colonization is so low, particularly on peaty soils, that H. annosum may not become permanently established in stands on these site types, even if ambient spore loads increase.
Abstract: Summary On 48 sites throughout Scotland and north England freshly cut stumps were either inoculated with basidiospores of H. annosum or allowed to become infected naturally. Sites were in first rotation plantations growing in high rainfall or low rainfall areas on either peat or mineral soils. After 2 years, infection varied greatly between sites. It was generally much higher following inoculation, but otherwise little of the variation can be explained. Overall, only 10.5 per cent of stumps became infected naturally; colonies were generally small and almost half the stumps contained only homokaryons. Colonization took place principally in the heartwood but stumps sampled 8 years after inoculation showed that in contrast to previous findings this did not prejudice long-term survival. The cross-sectional area of each stump occupied by H. annosum at two years was also not a good predictor of survival. There was a marked decline in survival of H. annosum in stumps sampled after 8 years, which implied a corresponding decline in the overall level of incidence to only 2.8 per cent across all sites. Even in those stumps in which the fungus survived, it failed to colonize two-thirds of the available roots. These results reinforce the conclusions of earlier work that there is a low risk of serious disease on peat soils in the uplands. It is suggested that for Sitka spruce stumps on wet sites, the risk of successful colonization is so low, particularly on peaty soils, that H. annosum may not become permanently established in stands on these site types, even if ambient spore loads increase. By contrast, on mineral soils in low rainfall areas, the risk of a build-up of inoculum in unprotected thinning stumps and the transfer of infection to residual trees in the stand is much higher.
TL;DR: A stocking assessment model was developed to assist with growing space allocation of pure and mixed-species stands of Scots pine and Norway spruce undergoing uneven-aged management based on data from a site in southern Finland.
Abstract: Summary Two- and three-aged stands are alternative structures that can provide continuous cover and a diversity of tree sizes. The silviculture of these multi-aged structures consists, in part, of treatments to allocate growing space to understorey and overstorey stand components, and thereby affect stand increment and subsequent stand structure. A stocking assessment model was developed to assist with growing space allocation of pure and mixed-species stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) undergoing uneven-aged management based on data from a site in southern Finland. This model used individual tree leaf area, as represented by sapwood area, as a driving variable and stand leaf area index as a limiting condition. The model assists researchers and forest managers with the design and assessment of a variety of structures that might be formed by selection treatments. The model can estimate stem volume increment and average tree vigour under different stocking regimes. In comparison to observed results from a series of silvicultural treatment plots in southern Finland, the predictions from the model were good. The stocking assessment model is useful for assessing different allocations of growing space in stands with several age classes and stands undergoing conversion to uneven-aged management.
TL;DR: In an analysis of 495 sites of ancient woodland throughout Great Britain, regional trends in ground flora species composition were explained primarily by climatic and soil variables, while the most important variable determining species richness was soil pH.
Abstract: Summary The ground flora in ancient woodlands is affected by a wide range of factors at a range of scales. In an analysis of 495 sites of ancient woodland throughout Great Britain, regional trends in ground flora species composition were explained primarily by climatic and soil variables, while the most important variable determining species richness was soil pH. In this analysis, ~85 per cent of the variation in ground flora composition could not be accounted for and was probably a result of local variation in a range of ecological processes including grazing by vertebrates. Within sites, the use of exclosures indicates that large herbivores may have a dramatic impact on vegetation structure and composition, but it is a very crude tool. The exclosures are often too small, and measurements do not allow for variations in the density or seasonality of grazing and ignore the fact that plant responses are typically non-linear. Manipulation of grazing levels is critical if we are to understand the impact of grazing on vegetation structure and composition. Individual species vary in their responses to grazing. A population approach is used to illustrate how it is possible to explore how individual species respond to grazing. This is illustrated with reference to Anemone nemorosa and how intermediate levels of grazing are expected to favour this species. Complex, and as yet poorly understood, feedback mechanisms between the plant and the grazing animal will contribute to the spatial structuring of grazing impacts on the woodland ground flora. A major challenge for predicting the impact of grazing on plant populations and communities is the quantification of the spatial grazing pattern.
TL;DR: A utility-maximizing model of farmer behaviour is used to explore how farmers react to incentives and the efficiency of voluntary schemes and in particular their additionality and the impacts on employment of farm level forestry in comparison with other types of planting are assessed.
Abstract: Summary Since 1987 the UK government has operated a farm woodland policy which uses incentive payments to encourage the establishment of woodlands by farmers. This paper uses a utility-maximizing model of farmer behaviour to explore how farmers react to incentives. An assessment is then made of farmer objectives when entering the Farm Woodland Premium Scheme and a logit model is used to determine which contextual factors are good predictors of uptake. Farm size and the proportion of the farm area in existing woodland were significantly associated with an increased probability of entry into the scheme. The paper then explores the efficiency of voluntary schemes and in particular their additionality. The paper finishes by assessing the impacts on employment of farm level forestry in comparison with other types of planting.
TL;DR: Richness and composition of plant and bird communities were used to evaluate the importance of seven within-forest factors on biodiversity in fragmented coppice forests in south-western France, finding plant richness varied strongly between YSL classes, was independent of STANDARD, increased with TREE and was higher in collective owned forests.
Abstract: Summary Richness and composition of plant and bird communities were used to evaluate the importance of seven within-forest factors on biodiversity in fragmented coppice forests in south-western France. Plants and birds were sampled on the same 98 plots. Plant abundance‐dominance was measured on 400 m 2 plots. Birds were sampled using a 50-m fixed radius point-count method in the early and late periods of the breeding season. The selected factors were: years since logging (YSL), retention of standards (STANDARD), ownership (OWNER), distance to the nearest edge (EDGE), tree richness (TREE), density of vegetation in low (ST2) and high (ST16) strata. Paired comparisons of richness were carried out between YSL classes, according to other variables. The respective influence of each variable was evaluated using adapted CCA (canonical correspondence analysis) on plant and bird composition. Plant richness varied strongly between YSL classes, was independent of STANDARD, increased with TREE and was higher in collective owned forests. Bird richness seemed to be independent of YSL and was higher in low YSL plots with standards. Bird and plant richness was not correlated. Plant community composition was mainly explained by YSL/ST16 on the first axis and by OWNER on the second axis. STANDARD and OWNER explained bird community composition. OWNER must be considered as a synthetic variable. This could be useful in adapting forestry practices for a better management of biodiversity, taking into account the very different taxonomic groups involved.
TL;DR: Forking is one of the major stem deformities in ash and if production of quality timber is an important objective of management, forking is tolerable above 6 m in height as most of the timber value is in the lower part of the stem; below 6 m it is a major defect.
Abstract: Forking is one of the major stem deformities in ash (Fraxinus excelsior L.). Ash is prone to such damage because the terminal bud is flanked by a pair of lateral buds in the axils of the uppermost leaves of the shoot. If the terminal bud is lost or damaged and fails to elongate in the spring there are two possible successors which, if both develop, will form a fork. If production of quality timber is an important objective of management, forking is tolerable above 6 m in height as most of the timber value is in the lower part of the stem; below 6 m it is a major defect. Silviculturists have traditionally aimed to reduce the effects of forking on the final crop by planting many more trees than required and removing forked and other poorer trees by thinning. In some species, e.g. beech, production of forks is part of natural morphological The influence of spring frosts, ash bud moth (Prays fraxinella) and site factors on forking of young ash (Fraxinus excelsior) in southern Britain
TL;DR: Chemical and biological aspects of above-ground leaf biomass and nutrient content, redistribution of leaf litter and nutrient return to the soil, seasonal foliar dynamics and nutrient-use efficiency were studied in four Castanea sativa Mill forests of varying ages.
Abstract: Summary Chemical and biological aspects of above-ground leaf biomass and nutrient content, redistribution of leaf litter and nutrient return to the soil, seasonal foliar dynamics and nutrient-use efficiency were studied in four Castanea sativa Mill. forests of varying ages near Salamanca (Spain), Montpellier (France) and Catania (Italy). From 49 felled, measured and weighed trees, leaf biomass was determined for each tree relative to their diameter at breast height (d.b.h.). It was possible to establish a single regression equation: Biomass = a(d.b.h.) b . Young stands had much lower leaf biomass values: (1600 kg ha‐1 and 1500 kg ha‐1) than the two older stands, (3900 kg ha‐1 and 4100 kg ha‐1 respectively). The amounts of the nutrients immobilized in leaf biomass followed the order: N > K > Ca > Mg > P. The amounts of immobilized N, P, K and Mg were less in young stands than old stands; whereas the amounts of Ca were greater in the young stands. N and P translocation to perennial parts followed the same relationship as nutrient immobilization in above-ground leaf biomass, the K translocation differed in the French stand, whereas for Ca, the pattern differed for the two Italian stands. Magnesium does not follow any pattern. The Spanish plot reabsorbed greater amounts of the nutrients considered, except for P, where the greatest amount occurred in an Italian stand. The French site resorbed similar proportions of N as the Italian stands and considerably lower proportions of Mg and K than the other three stands. The two Italian stands resorbed the same proportions of K and Mg, Fossa la Nave greater proportions of Ca, and Piano Porcheria of P.
TL;DR: The problem of epicormic shoots and their control is a common theme of oak silviculture in North America and Europe and their presence affects value using French log grading rules.
Abstract: The problem of epicormic shoots and their control is a common theme of oak silviculture in North America and Europe. The earliest reports are from Europe, where Pontey (1810), for example, described epicormic shoots and the knots they cause as ‘an evil of immense magnitude’. Foresters in North America began to realize the significance of epicormic shoots when virgin forests had been cleared and second growth stands were being brought under management (Kormanik and Brown, 1964). The presence of epicormic shoots on oak is regarded as undesirable because they can reduce the quality and value of timber: Hedlund (1964) described how they reduced the quality of 23 per cent of logs by two or more grades and Courraud (1987) showed how their presence affects value using French log grading rules. Even superficial epicormic shoots will suggest to timber buyers that individual knots, or clusters of them, may be present deeper in the log, resulting in lower prices being paid. The population of epicormic shoots on an oak tree is determined by three main factors: (1) the initiation of buds, (2) the release of buds from dormancy and (3) survival of epicormic shoots. Whilst it is generally accepted that most epicormic branches develop from suppressed buds which become embedded in the bark, the reasons for their release from dormancy are not well understood (Bowersox and Ward, 1968; Roussel, 1978; Wignall et al., 1987; Harmer, 1988; Wignall and Browning, 1988; Spiecker, 1996; Fontaine et al., 1997). The survival of epicormic shoots on Quercus mongolica var. grosseserrata has been studied by Yokoi and Yamaguchi (1996) who confirm that light is important; other likely factors are oak leaf roller moth (Tortrix viridana L.) and mildew (Microsphaera alphitoides Grif. Production of epicormic shoots on oak (Quercus robur): effects of frequency and time of pruning
TL;DR: It is concluded that urea provides an effective means of control against present ambient spore loads against Sitka spruce stumps against infection by spores of H. annosum.
Abstract: Summary The ability of a 17 per cent solution of urea to protect Sitka spruce stumps against infection by spores of H. annosum was tested on 24 sites throughout Scotland and north England. After treatment, stumps were either inoculated with basidiospores or exposed to natural infection. Urea failed to reduce the incidence of infection arising from inoculation but it reduced the level of natural infection by two-thirds from a mean of 8.8 per cent to 3.5 per cent. In inoculated stumps that became infected, urea significantly increased the extent of colonization, particularly on peat soils, but this effect was not detected in naturally infected stumps. The fungus was largely confined to the heartwood and it is suggested that colonization may have been stimulated by the addition of nitrogen. It is concluded that urea provides an effective means of control against present ambient spore loads.
TL;DR: Simple techniques were used to overcome the problems associated with estimating breeding values for a number of traits prior to calculating parental multi-trait index values for over 800 plus trees within the Sitka spruce General Breeding Population (GBP).
Abstract: Summary Simple techniques were used to overcome the problems associated with estimating breeding values for a number of traits prior to calculating parental multi-trait index values for over 800 plus trees within the Sitka spruce General Breeding Population (GBP). Progeny from different trees were planted in half-sib tests in different years. It took an 11-year period involving numerous sites of differing quality to complete the test establishment. The estimation of parental breeding value was restricted to across-sites analysis involving the mean performance of open-pollinated progeny collected from each plus tree planted over a maximum of three representative sites; in each case the data from each site were weighted by the family heritability for the trait and site. Standard parameter estimates for family heritability and phenotypic and genetic correlations, and standard values of the control common to all experiments, were calculated by averaging estimates over all across-sites analysis. Ranking of re-selected parents to form the GBP was based on index values calculated using multi-trait index selection. Two hundred and forty reselected parents have been allocated to one of four sub-lines of equal mean index value. Plus trees have been ranked within each sub-line based on index value. Full-sib controlled pollinations according to an amended assortative mating procedure are now planned between selections within each sub-line. The second generation breeding population will be created by selecting the best individuals within the best families.