Farm Woodland Research Articles

Tree and livestock productivity in relation to tree planting configuration in a silvopastoral system in North Wales, UK

Silvopastoral systems in Europe offer the potential of introducing environmental benefits while at the same time increasing the diversity of farm outputs. The establishment of new silvopastoral systems by planting young trees into existing pasture was investigated at a site in North Wales, UK. Two tree species, sycamore (Acer pseudo-platanus L.) and red alder(Alnus rubra Bong.), were planted into pasture at a range of densities and planting arrangements. Growth of trees planted in farm woodland blocks (2500 stems ha−1) was compared with the growth of trees planted at 400 stems ha−1 in clumps and dispersed throughout the plot and at 100 stems ha−1 (dispersed). Over the first six years after planting, alder trees were significantly taller and larger in diameter than sycamore. Sycamore trees planted at close spacing in farm woodland or clumped arrangements were significantly larger in diameter than widely spaced sycamore at 100 and 400 stems ha−1. Livestock productivity was unaffected by the presence of trees during the six-year establishment phase of the system. The planting of trees in a clumped pattern appears to combine silvicultural benefits to tree growth with agricultural benefits of maintaining livestock production while trees are established.

Summer and winter bird communities in recently established farm woodlands in lowland England

This paper examines the effects of woodland management and structure on the presence, abundance and species richness of birds in 65 farm woodlands created under agri-environment schemes in southern and central England. It also compares the avifauna of the woodlands with that of other farmland habitats for a subset of 11 farms. Over 50 different bird species were recorded in the woodlands in winter and breeding seasons. The geographical location, area, age and conifer content of the woodland, nature of the surrounding farmland and adjoining field boundaries, and the use of herbicides affected the occurrence of individual species at the sites. Species richness was positively associated with woodland area and sites connected to hedgerows with trees had more species than sites connected to treeless hedgerows. Smaller woodlands tended to support a greater overall abundance of birds than larger woodlands. Overall bird abundance and species richness was higher along field boundaries such as hedgerows and walls or ditches with scattered trees than in the farm woodlands. The latter, however, supported a greater overall abundance and number of species of birds than surrounding cropland. It is suggested that the creation of small farm woodlands provides habitat for several bird species that are currently declining and is a valuable tool for promoting bird diversity in Britain. To maximise bird diversity, the planting of small woodlands should coincide with the preservation of existing woodlands, trees, and hedgerows.

The role of farm woodland

Ed. by P. J.Burgess, E. D. R. Brierley, J. Morris and J.Evans. 202 pages. Oxford, UK: Bios Scientific Publishers Ltd, 1999. £30.00 p/b. ISBN 185996 133 9 This collection of papers presented at the ‘Farm Woodlands for the Future’ conference at Cranfield University, Bedfordshire, UK in 1999 covers various aspects of the development and promotion of farm woodland in the context of its socioeconomic role, economics, value for shelter, biodiversity and landscape, and agroforestry. To begin, a senior MAFF employee (Coates), involved in policy development, discusses the role of the UK Government in encouraging farm woodland and rural development, giving useful statistics on areas planted to woodland under farm woodland schemes (FWS and FWPS), and pinpointing key targets for future regulation and grants. The rapid change in farmers’ attitudes to afforestation in the Republic of Ireland is discussed by Bulfin: grants and premiums offer powerful incentives to plant, ensuring a secure income. Moving to The Netherlands, the current participation of farmers in set-aside, nature conservation and landscape management is set by Wiersum & van Laar in the perspective of the social role of farm woodland in the last two centuries. Hislop and co-workers deal with the role of the Farm Shelter Audit in the assessment of woodland shelter needs, and the pros and cons of new woodland and woodland biodiversity are discussed by Kirby and co-workers. Continuing the theme of biodiversity, Helliwell describes a simple method of valuation of biodiversity based on ‘ancientness’, vascular plant species content, structure and geographical relationships to other habitats. In ‘Landscape valuation of farm woodlands’, Thomas & Price suggest that traditional environmental economics are unlikely to give reliable monetary values; instead, subjective landscape evaluation scales might be transformed onto a monetary scale based on the cost of travel to different landscapes. Burgess and co-workers describe the four systems which they established at UK demonstration sites: poplar and traditional broadleaf woodland; and two agroforestry systems. Although the adjusted net cost of the silvoarable system seemed the highest, trees were incorporated into an arable landscape relatively inexpensively, with concomitant environmental benefits. Blyth (‘Developing a methodology for assessing the financial viability of farm woodlands’) describes a system that serves as a realistic-looking guide to the relative financial viability of a range of woodland systems. Hyttinen & Niskanen describe their guidelines for aiding the necessary development of tools to measure, monitor and compare the economic sustainability of forestry in the EU. Sanders looks at the effect of woodlands on farm valuations from the viewpoint of an estate agent: benefits are greatest where agricultural productivity is high; effects are positive where woodlands add to shooting, shelter and landscape, but public access may have a negative effect. In ‘Adding value to farm timber’ Jenkins comments that selling timber as square-edged stock or hardwood strip flooring greatly increases its value. McAdam, considering agroforestry as a sustainable land use option, reviews research in the UK and comments that agroforestry can contribute to sustainable rural development and that silvopastoral systems also enhance biodiversity, improve the physical environment and benefit animal welfare. Two papers each consider a single species. Growth of poplar is less profitable than agriculture on land in the UK, according to Thomas and co-workers who describe a bio-economic model which can be used to examine the impact of government intervention and other factors. Dawson discusses the social, environmental and economic value of short-rotation coppice willow, Salix, as an energy crop: the costs of establishing coppices, and of producing energy on the farm are marginal; bio-remediation treatment of waste based on willow-coppicing brings additional benefits. There are three reviews of the roles of various bodies (planting by the latter two is only limited) in the promotion of farm woodland: the Forestry Commission (Rollinson); community forests (Feline); and the National Forest (Williams). Farm woodlands for the future is not a textbook on farm-woodland management. Clearly there are gaps (how to plant and nurture young trees, for example), but anyone interested in farm woodlands should read this collection of highly relevant up-to-date material.

Vegetation changes during 100 years of development of two secondary woodlands on abandoned arable land

Broadbalk and Geescroft Wildernesses were abandoned as arable fields in the 1880s and allowed to develop with little further direct human intervention. Both have now developed into mature mixed deciduous woodland, variants of National Vegetation Classification type W8, Fraxinus excelsior — Acer campestre — Mercurialis perennis woodland. In addition, a portion of Broadbalk Wilderness has been maintained as grassland by removing woody colonists and, latterly, by grazing. The succession from arable to woodland has been recorded at irregular intervals for more than 100 years. Despite its limitations, this is the longest record of the floristic development of secondary woodland on farmland in the UK. Woody species colonised Broadbalk within 10 years, but at Geescroft they were not recorded until 30 years after abandonment. At present, both sites have good overstorey canopies with well developed understories which provide densely shaded conditions. There are currently 17 species of shrubs and trees at each site. The transition from a flora of mainly light-demanding species to shade tolerant species took place within 20–40 years of abandonment. The development of the shade flora within the woods has been characterised by: (1) a high turnover of species; (2) a failure to colonise by some shade-bearing species in the vicinity; and (3) inability of some colonists to spread beyond the wood margins. This appeared to be associated with: (1) dense shade from the closed woodland canopy; (2) competition from established ground flora dominants, particularly Hedera helix; (3) lack of suitable moist soils and open space habitats within the woods; and (4) pronounced acidification of soils in one wood. Some implications for new farm woodland creation are discussed.

Voluntary incentive schemes for farm forestry: uptake, policy effectiveness and employment impacts

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.

Distributions of birds in lowland agricultural landscapes of England and Wales: How distinctive are bird communities of hedgerows and woodland?

Within agricultural landscapes many species of birds depend on hedgerows and woodland, but few studies have examined their relative importance as habitats for breeding birds. Breeding bird communities in hedgerows and woodland in lowland England and Wales were compared in terms of species richness and similarity of species composition. The preference of individual species for hedgerows and woodland was also assessed. The data were drawn from 33 farmland and 35 woodland Common Birds Census plots for 3 years: 1990, 1993 and 1996. Woodland plots were significantly richer in species than farmland plots. Species number on farmland plots increased linearly with the cover of farm woodland and non-linearly with density of total hedgerow. Species number increased with density of non-roadside hedgerows, but not with density of roadside hedgerows. Although the farmland and woodland plots supported distinctive bird communities, there was considerable overlap between them in species composition. The similarity between the species composition on individual farms and that theoretically possible for woodland increased significantly with the cover of farm woodland, hedgerow density and the total amount of woody habitat present within the farmland plot. Canonical correspondence analysis and preference indices indicated that seven species could be regarded as hedgerow specialists: Dunnock Prunella modularis, Whitethroat Sylvia communis, Lesser Whitethroat S. curruca, Linnet Carduelis cannabina, Goldfinch C. carduelis, Greenfinch C. chloris and Yellowhammer Emberiza citrinella. Species showing clear preferences for woodland were: Tawny Owl Strix aluco, Marsh Tit Parus palustris, Coal Tit P. ater, Goldcrest Regulus regulus, Spotted Flycatcher Muscicapa striata, Treecreeper Certhia familiaris, Nuthatch Sitta europaea, Great Spotted Woodpecker Dendrocopos major, Chiffchaff Phylloscopus collybita and Blackcap Sylvia atricapilla. The habitat needs of the hedgerow specialists show considerable variation and do not always coincide with the hedgerow structures that support the greatest numbers of bird species and highest densities of birds. Management strategies that maintain a diversity of hedgerow structures are, therefore, desirable. Hedgerow and woodland bird communities are essentially complementary and habitat creation initiatives in lowland agricultural landscapes should not be excessively weighted towards one habitat or the other.

Potential for ammonia recapture by farm woodlands: design and application of a new experimental facility.

There has been increasing pressure on farmers in Europe to reduce the emissions of ammonia from their land. Due to the current financial climate in which farmers have to operate, it is important to identify ammonia control measures that can be adopted with minimum cost. The planting of trees around farmland and buildings has been identified as a potentially effective and low-cost measure to enhance ammonia recapture at a farm level and reduce long-range atmospheric transport. This work assesses experimentally what fraction of ammonia farm woodlands could potentially remove from the atmosphere. We constructed an experimental facility in southern Scotland to simulate a woodland shelterbelt planted in proximity to a small poultry unit. By measuring horizontal and vertical ammonia concentration profiles within the woodland, and comparing this to the concentration of an inert tracer (SF6) we estimate the depletion of ammonia due to dry deposition to the woodland canopy. Together with measurements of mean ammonia concentrations and throughfall fluxes of nitrogen, this information is used to provide a first estimate of the fraction of emitted ammonia that is recaptured by the woodland canopy. Analysis of these data give a lower limit of recapture of emitted ammonia, at the experimental facility, of 3%. By careful design of shelterbelt woodlands this figure could be significantly higher.

Vegetation management in farm forestry: a comparison of alternative methods of inter-row management

Forestry Commission and ADAS experiments on the inter-row management of vegetation within wide spaced (3 m between rows) new farm woodlands are described. Strip weeding with mowing proved to be a cost effective method of establishing new woods on fertile lowland former agricultural sites. Sowing kale was also effective, and provided game cover early in a woodland's life. Sowing of a grass-wild flower mix inter-row enhanced diversity, but can be expensive, and seeded species need to be chosen carefully. Maintaining completely weed-free conditions maximized tree growth, but was costly and impractical. However, maintaining around 90 per cent weed-free conditions can be achieved relatively cheaply, although the potential for leaching and soil erosion may be increased. Carrying out no vegetation management significantly reduced tree growth and survival, and is not recommended. Planting trees at closer spacings (2 x 2 m or less) may be a quicker and more reliable means of establishing a woodland environment, within which other objectives can be achieved, if necessary through carrying out an early thinning or respacing regime.

Information for Policy Design: Modelling Participation in a Farm Woodland Incentive Scheme

Incentive schemes which use farmers and landowners as agents of policy are now the main driving force for modifying the countryside environment. Nevertheless, policy‐makers lack quantitative models that describe farmers' response to schemes, and specifically their entry decisions. This paper examines the benefits from modelling entry decisions with and without additional information generated through surveys of participants and non‐participants. It uses logit models to predict the probability of entry into a farm woodland incentive scheme, initially using only those explanatory variables that are available to policy‐makers from the annual farm census. The model performs well in identifying those factors pre‐disposing farmers to entry. The potential gains from enhancing the information set by incorporating lifestyle and other variables not recorded in the census are examined. The cost of additional surveys, and their small sample size compared with the census, casts doubt on the value of such an approach which may reduce rather than enhance predictive power.

The macrolepidoptera of farm woodlands: determinants of diversity and community structure

The Farm Woodland Scheme, which provided incentives to convert agricultural land to timber production, contained an implicit assumption that farm woodlands produce important benefits for wildlife. The moth fauna of 18 farm woodlands in the Vale of York was surveyed between May and November 1991. The aims were twofold. The first was to determine if there were benefits for moth species diversity. The second was to ascertain whether concepts of island biogeography and the plant species richness of the woods were related to the moth species composition.

An economic evaluation of alternative genetic improvement strategies for farm woodland trees

A cost-benefit analysis (CBA), focusing on the Net Present Value (NPV) of a current genetic improvement programme for broadleaved trees was performed using Monte Carlo simulation, with an add-on software package (‘@RISK’) specifically designed to take account of the uncertainty associated with long-term projects. The CBA was undertaken by evaluating the total cost of achieving a given estimated genetic gain via each of the breeding strategies considered. The estimated values of genetic gain were then expressed in terms of the increased value of timber output. Cash flows were based on current estimated tree establishment costs and anticipated productivity of the four tree species included in the programme (ash, Fraxinus excelsior ; sycamore, Acer pseudoplatanus ; wild cherry, Prunus avium ; and sweet chestnut, Castanea sativa ), when grown primarily for a timber crop. The results of the NPV analysis indicated that tree improvement could be cost-effective for small genetic gains, but that current breeding strategies differed markedly in their cost-effectiveness. Improvement scenarios based on conventional selection and testing techniques, such as simple mass selection and recurrent selection (seed orchards), were found to be the most cost-effective at a discount rate of 6 per cent. In contrast, tree improvement scenarios based on clonal techniques consistently ranked lowest, despite the much higher genetic gains achieved. The use of clonal techniques was found to be particularly hard to justify with broadleaved tree species of relatively low timber value. Overall, with the current state of broadleaved timber markets in the UK, and the current areas being planted, investment in basic genetic improvement of high-value timber species appears financially worth while. The estimated direct additional financial benefit to growers, if new planting is undertaken with improved stock as opposed to unimproved stock, is estimated to range from £38 ha −1 with Simple Mass Selection to £100 ha −1 with Simple Recurrent Selection.

Small Mammals in Farm Woodlands: The Effects of Habitat, Isolation and Surrounding Land-Use Patterns

1. The results of this study, which surveyed 38 farm woods ranging in size from 0.05 to 4.45 ha, demonstrated clearly that the dynamics of wood mice Apodemus sylvaticus and bank vole Clethrionomys glareolus populations in small woods are strongly influenced by the landscape around the woods, for example the distance to neighbouring woods, abundance of hedges and types of crops grown, as well as the habitat within the wood. 2. In terms of the habitat features of the woods, the maturity of the wood and the amount of understorey and overstorey cover were important for both species, while the availability of herbaceous plants influenced bank vole abundance. 3. Wood mice, in particular, were influenced by the types of crops grown in neighbouring fields. Their abundance in spring, the proportion of juveniles in the autumn and the extent to which the population increased from spring to autumn were all influenced by the proportion of adjoining fields that were planted with wheat and/or oilseed rape. 4. Isolation variables, such as the distance to the nearest large wood and the extent of adjoining hedgerows, influenced both wood mice and bank vole populations. Populations of both species increased more from spring to autumn in more isolated woods. This was probably because of reduced opportunities for dispersal and the shortage of alternative woodland habitat for animals moving off the fields after harvest. Woods well connected with hedges supported higher densities of both wood mice and bank voles. 5. Within the size range of woods examined here, no effect of woodland size was found on the probability of catching wood mice or bank voles or their abundance in either spring or autumn. The data suggest that even very small farm woods are important as refuges for small mammals, particularly after harvest when arable fields provide little cover.

Functional biodiversity of microbial communities in the rhizospheres of hybrid larch (Larix eurolepis) and Sitka spruce (Picea sitchensis).

The diversity of microorganisms associated with trees and their different functional capabilities is thought to be a consequence of variation in carbon compounds in the rhizosphere. We used the Biolog(R) system (Biolog Inc., Hayward, CA), a redox-based test, to construct sole carbon source utilization profiles (metabolic fingerprints) of microbial communities from the rhizospheres and rhizoplanes of hybrid larch (Larix eurolepis A. Henry) and Sitka spruce (Picea sitchensis Bong. Carr.) taken from a farm woodland site and two second-rotation plantation forest sites. Canonical variate analysis (CVA) of carbon utilization data differentiated among the microbial communities from the three forest sites, with the greatest discrimination between the farm woodland and the two second-rotation forest sites. Carbohydrates and carboxylic acids were the substrates responsible for this discrimination. Carbon profiles of the microbial communities from the rhizospheres of the two tree species also clustered when evaluated by CVA, as a result of differences in utilization of carboxylic acids and amino acids, suggesting that these tree species differ in the exudates they produce. Isolation and enumeration of organisms confirmed that there were qualitative and quantitative differences in the culturable populations of microorganisms at the different sites and between tree species. We conclude that Biolog is a useful technique for evaluating the functional diversity of microbial communities; however, to interpret the results accurately, they must be assessed in conjunction with the actual carbon substrates available in the particular ecosystem under study.

Constraints on farm woodland planting in England: a study of Nottinghamshire farmers

Summary A recent change in British agricultural and forestry policy has been the shift towards the encouragement of substantial planting of new woodland on farmland in England. Previous studies of farm woodland planting are reviewed. A study of the attitudes of 30 farmers on the Bunter Sandstone in western Nottinghamshire to the establishment of new farm woodland is assessed. It is concluded that new policy instruments such as special farm woodland planting grants and the establishment of Community Forests and special regional forestry initiatives have not yet brought about any significant change in the general opposition of farmers to the conversion of agricultural land to woodland.

The impact of hedges and farm woodlands on woodpigeon ( Columba palumbus) nest densities

The creation of new woodlands on farms is likely to increase the local population of a number of pest species (e.g. rabbit, Oryctolagus cuniculus; grey squirrel, Sciurus carolinensis) including the woodpigeon ( Columba palumbus). Data on the numbers of woodpiegeon nests were gathered annually between 1965 and 1989 from 71 woods and hedgerows in Lincolnshire, UK. Information on the size, shape and tree composition of the sites was also obtained. Nest density was related to both the size and shape of the site. Hedgerows had a significantly higher nest density (mean±SE 6.95±0.78 nests ha −1) than woods (2.07±0.38 nests ha −1). There was a significant negative correlation between nest density and area of the wood, and a significant positive correlation between nest density and the proportion of edge habitat within the wood (i.e. that within 20 m of the boundary). Hawthorn seemed to be a preferred tree for nesting, but none of the major tree species currently being planted under Farm Woodland schemes in the UK had any significant effect upon nest density. If minimising the increase in woodpigeon nest sites is the primary concern, then trees should be planted to extend existing woods wherever possible, rather than to create new copses and shelter belts.

Distribution of arthropod species across the margins of farm woodlands

The distribution of ground-dwelling carabid beetle (Carabidae) and spider (Araneae) species on a farm woodland-arable field transect was examined by pitfall trapping. The woodland edge zone was found to have an elevated species richness of the two faunal groups studied. The woodland and field habitats support distinct species assemblages. At the habitat interface the community was composed of a mixture of woodland and field species. Species associated with the woodland were found to occur in the field habitat and vice versa. The edge effects noted did not extend beyond approximately 5 m into the farm woodland. The presence of the farm woodlands increases the local species diversity of the faunal groups studied.

Responses of soil Cryptostigmata across the boundary between a farm woodland and an arable field

Responses of soil Cryptostigmata across the boundary between a farm woodland and an arable field

Biogeography and Diversity of Ground-Dwelling Arthropods in Farm Woodlands

Biogeography and Diversity of Ground-Dwelling Arthropods in Farm Woodlands

Plant species richness in farm woodlands: M. B. Usher, A. C. Brown & S. E. Bedford, Forestry, 65(1), 1992, pp 1–13

Plant species richness in farm woodlands: M. B. Usher, A. C. Brown & S. E. Bedford, Forestry, 65(1), 1992, pp 1–13

The Distribution of Grey Squirrel Dreys in Farm Woodland: The Influence of Wood Area, Isolation and Management

Sixty-eight deciduous woodlands, ranging in size from 0.2 to 12.5 ha, were surveyed in East Anglia, UK, and the density of grey squirrels Sciurus carolinensis estimated from drey counts. Squirrel dreys were more likely to occur in woods that (i) were larger, (ii) were closer to another wood of at least 5 ha in size, (iii) contained oak Quercus spp., beech Fagus sylvatica or hazel Corylus avellana, and (iv) were surrounded by a greater density of hedgerows. The overall density of woodland in the vicinity, the distance to a wood of at least 0.5 ha in size, and the presence/absence of five other tree species did not influence squirrel drey distribution between the woods