Forest Management and Plant Species Diversity in Chestnut Stands of Three Mediterranean Areas

Over many centuries, chestnut fruits had an important role as food, while chestnut wood was used for local purposes. Today sweet chestnut stands are very common around the western Mediterranean Basin, and it is necessary to analyze the dynamic of plant species diversity in different chestnut stand types (groves and coppices) to guide management strategies that will allow the conservation of biodiversity. Our objective was to analyze consequences on plant species diversity of various management strategies in chestnut stands of three Mediterranean areas, Salamanca (Spain), the Cévennes (France), and Etna volcano (Italy). We found that plant species diversity is different according to management types; it is higher in groves than in coppice stands. We also demonstrated that Castanea sativa cultivated groves were characterized by small heliophillous therophytes. C. sativa abandoned groves, mixed C. sativa–Quercus pyrenaica coppice stands, Q. pyrenaica coppice stands, and young C. sativa coppice stands were characterized by hemicryptophytes with anemochorous dispersal mode and chamaephytes. Medium and old C. sativa coppice stands (that differ by the shoot age) were characterized by phanerophytes with zoochorous dispersal mode. Human perturbations maintain a quite high level of species diversity. In contrast, the abandonment of chestnut stands leads to homogeneous vegetation with decreasing diversity. One solution could be to maintain a landscape mosaic constituted of diverse chestnut stands modified by human activities (groves, cultivated or abandoned, and coppice stands). This could enhance regional plant diversity.     

Plant species diversity changes in abandoned chestnut (Castanea sativa) groves in southern France

Over the last few decades, marked land use changes have taken place in many Mediterranean ecosystems. For example, many chestnut groves in France are now abandoned and have turned into 'natural' coppice stands while others are now clear-cut every 10 or 15 years for wood. Species composition and life form diversity of the plant communities have changed markedly both in the abandoned groves and in the periodically clear-cut coppice stands. What are the consequences of these changes on biodiversity at local and regional scales, and what are the implications for 'new forestry' management intended to conserve biodiversity at the same time as it optimizes productivity and profitability? To answer these questions we studied plant species diversity in the understorey strata along a successional gradient including cultivated grove; abandoned grove; young (15 years old), medium (40 years), and old (>55 years) coppice stands. The results showed that species richness decreased quickly but not steadily along this gradient, but life-form spectra data highlighted that the high levels of plant species biodiversity in cultivated groves were due primarily to the large number of therophytes (annual plants). At a shorter time scale, we also studied the consequences of experimental clear-cutting on plant species biodiversity. Direct measurements over four years showed that species richness and diversity in the understorey increased in the first two years after clear-cutting, but decreased during the 3rd and 4th years. This decrease corresponded closely with a steady increase in Leaf Area Index of the forest canopy. These results have been used to suggest some possible ways to manage the biodiversity in these ecosystems.     

Role of domestication in shaping <Emphasis Type="Italic">Castanea sativa</Emphasis> genetic variation in Europe

The genetic structure of sweet chestnut (Castanea sativa Mill.) across Europe was assessed using 73 inter-simple sequence repeat markers to screen 1,768 individuals from 68 stands distributed across 29 sites in five European countries (Italy, France, Spain, Greece, and UK). At each site, trees were sampled from three distinct management types (domestication levels): naturalized stands, managed coppice, and grafted fruit orchards. In more than a third of the orchards, nonlocal genetic material (grafted clones) were evident, showing (as predicted) large differences from the other two domestication levels for most of the within-population genetic diversity parameters estimated. Randomly generated linkage disequilibrium analysis revealed weak though significant differences in two-locus allelic correlations between naturalized stands and coppice, suggesting that long-term management techniques may influence the genetic makeup of the populations. Multivariate analysis revealed the existence of five distinct gene pools across the study area; three were located in Greece, one on the northwestern coast of the Iberian peninsula and a large gene pool covering the rest of the Mediterranean basin. The implications of the results are discussed in relation to developing conservation strategies for chestnut genetic resources in Europe.     

The effect of coppice management on moth assemblages in an English woodland

Coppice woodlands in Britain may become the target of increased management due to the rise in demand for woodfuel. The biodiversity value of sweet chestnut (Castanea sativa) coppice and the effect of coppice management upon this has received limited study. Moths were the focus of this study in an actively coppiced sweet chestnut woodland in southern England. Coupes, with between one and 20 years of coppice regrowth, were systematically sampled for night flying micro- and macro-moths and coppice structure and ground vegetation were described. Using differences in moth assemblage, three stages of coppice development were distinguished: with one-four, five-nine and more than 10 years of coppice regrowth. Differences in moth assemblage related to habitat conditions within each coppice stage. The young coppice stage moth assemblage was characterised by species typically associated with open habitats; moths of the middle coppice stage assemblage fed on trees and were species typically associated with open woodland and scrub habitats; moths of the mature coppice stage assemblage were species typically associated with closed canopy woodland and contained specialist species whose larval food consists of material such as lichen and decaying leaves. All three coppice stages supported species of listed conservation status; the mature coppice stage contained a distinctive range of scarce and threatened species. The study showed that active coppicing promotes a change in moth assemblage but consequently will temporarily eliminate many species of mature stage coppice. Management which provides a range of coppice age classes within a woodland, appears key in promoting moth diversity.     

Taxonomy and ecology of <Emphasis Type="Italic">Castanea sativa</Emphasis> Mill. forests in Greece

Castanea sativa Mill. is an important species of the Balkan Peninsula with high ecological and economic value. This article contributes to a phytosociological synsystematic approach of the C. sativa plant communities in Greece that covers the southern part of the Balkan Peninsula and describes the ecological parameters involved in their distribution and taxonomy. Phytosociological data have been collected from 14 mountainous areas across continental Greece, which are considered representative of the main forest types of C. sativa in the area. The 14 mountains demonstrate a variety of environmental conditions. Five communities (associations) and seven sub-communities (sub-associations) have been identified and described using TWINSPAN, Corespondence Analysis and the Braun-Blanquet classification scheme. Castanea sativa (chestnut) forests of Greece can be distinguished as three broad groups, defined primarily by their geographical distribution. In northern and central Greece chestnut stands are characterized by their high floristic homogeneity, which is reflected in the identification of only one community per region. Chestnut forests in northern Greece, in particular, exhibit strong floristic similarities with those of the rest of the Balkans. In southern Greece, on the other hand, the southern distribution limit of chestnut in the Balkans, there is a greater floristic diversity between the sampled mountains which is reflected in the presence of three confirmed communities and two sub-associations. Several factors have been identified as important in determining the structure and floristic composition of chestnut forests in Greece. Whilst climate and the grazing regime are influential, the degree of silvicultural management appears to be the most important factor determining the floristic composition of chestnut forests and their long-term sustainability.     

Dynamics of holm oak (Quercus ilex L.) coppices after clearcutting in southern France

Holm oak (Quercus ilex L.) forest is one of the most widespread biocoenoses in the southern part of France. Until recently, clearcutting of wood for domestic use was carried out every 20 years or so in these coppice stands. In order to study coppice stand dynamics after cutting this paper presents results of observations of some items describing the vegetation structure, the floral composition, and the life cycles in a holm oak coppice stand during a six year period after clearcutting. One of the questions addressed in this study was whether these coppice stands reach a steady state based on auto-succession, or if they continue to change. The results of the floristic changes after cutting suggest that the model of auto-succession best fits with the vegetation dynamics, even if changes in the density and life cycles of herbaceous species still exist six years after clearcutting.     

Livestock management in Natura 2000: A case study in a Quercus pyrenaica neglected coppice forest

Due to the European Habitats Directive, Quercus pyrenaica habitat has been protected within the Natura 2000 network for biodiversity conservation. Many of these habitats have been widely managed as coppice forest with silvopastoral use throughout Spain. Currently, in many of these oak coppices fuelwood extraction is neglected and grazing is the main use. Management plans required in the Directive should consider all these circumstances and offer an integrated approach to ensure a favourable conservation status of these habitats. We propose a three phase methodology to assess the ability of the habitat to support a given livestock density annually and seasonally, and to evaluate some of the physical impacts of grazing animals on the physical structure and development of the habitat. We applied the methodology to a neglected coppice forest that supports livestock at different periods. Results show that there is a possible compatibility between annual livestock food requirements and pasture production. Current grazing periods seem to fit the seasonal pasture productivity. Negative impacts were assessed on oak shrubland stands due to intense browsing and on low polewood owing to the high density of broken trees. On more developed stands, positive livestock impact was due to the control of the regrowth of coppice shoots. Acorn absence is a result of the previous coppice management. This negative impact may endanger long-term viability of Q. pyrenaica in the study area. We propose a process of conversion into high forest through a sequence of thinning to start sexual regeneration. In this proposal, livestock have an important role to ensure biodiversity, control the regrowth of coppice shoots and thinning low polewood stands.     

Correlation among soil enzyme activities under different forest system management practices

Soil enzyme activities were performed in three permanent no-till and unfertilised plots located in the South of Salamanca province (Spain), the first in a Castanea sativa Mill. paraclimax coppice (CC), the second in a chestnut orchard (CO) and the third in a Quercus pyrenaica Wild. climax forest (Oak), adjacent to the CO plot.We hypothesized that the activities of dehydrogenases, ureases, acid phosphatases, arylsulphatases and β-glucosidases in different forest ecosystems are involved in the carbon, nitrogen and phosphorus cycling and we report their relationship with each other and with physical, chemical and general biochemical parameters of the soils. The main aim of the study was to detect biological criteria for sustainable development in natural degenerate forests of Mediterranean Europe. For this, we used sweet Chestnut (C. sativa Mill) and Oak Q. pyrenaica Wild as models to better define the ecological conditions of these natural resources in terms of nutrient balance, physiology and biological diversity of their communities, to relate them to the conditions of exploitation and land-use changes, for the characterization of sustainable ecological systems.Furthermore, soil respiration was high and significantly different in the chestnut coppice stand than the other two stands, chestnut orchard and oak.Correlations between soil biochemical and soil microbiological variables showed that the three different forest management practices had also a strong effect on soil function conditions. In a discriminate analysis, CC and Oak were discriminated clearly, while CO was in the middle of the biplot sharing some properties with each of the two different groups. Thus, we proposed a soil property transition from the best soil structure and function properties at one chestnut management properties with low tree densities (CC and CO) to other with the worst ones at highest tree density conditions (Oak). According to natural soil conditions in Oak, we assumed that most of the enzyme activities reached their highest levels at highest C and N soil contents but at lowest soil base saturation percentage while they were not at all associated with P soil availability.     

The Role of Urban Structures in the Distribution of Wasteland Flora in the Greater Paris Area,France

Wastelands are likely to host a significant part of urban floristic diversity but have received limited attention because they are not considered interesting green zones. Here, we explore the potential role of wastelands in maintaining urban biodiversity to help define effective urban management plans. We quantified floristic diversity in 98 wasteland sites of Hauts-de-Seine, one of the most densely populated areas in France, and characterized the environmental parameters and spatial distribution of sites to identify some of the factors that influence plant species composition and to explore the impact of urban environment on the floristic interest of wastelands. Their floristic richness represented 58% of the total richness observed in the whole study area. Site richness depended on site area (the largest sites were the richest) and site age, with a maximum in sites of intermediate age (4–13 years). In the largest sites only (>2,500 m²), the floristic distance among sites was positively correlated with geographic distance, which suggests that migration of species among large sites partly controls local floristic composition. In contrast, the environmental distance among sites was not correlated with floristic distance. Finally, we showed that the presence of collective and individual dwellings within 200 m of a wasteland decreased its floristic rarity, whereas the presence of rivers or ponds increased it. We derive several recommendations to optimize the management of wastelands with respect to conservation of urban biodiversity.     

Determinants of diversity in afrotropical herbivorous insects (Lepidoptera: Geometridae): plant diversity,vegetation structure or abiotic factors?

Aim This study was conducted to investigate the potential of predicting alpha diversity and turnover rates of a highly diverse herbivorous insect family (Geometridae) based on vascular plant species richness and vegetation structure. Location The study was carried out on the south‐western slopes of Mount Kilimanjaro within a wide range of habitats between 1200 and 3150 m elevation. Methods The floristic and structural composition of the vegetation was recorded at 48 plots of 400 m². Geometrid moths were sampled manually at light sources located at the plot centres. Principal components analysis, redundancy analysis and multiple linear regression were used to explore how alpha diversity and species turnover of geometrid moths are related to vegetation structure and plant species richness. Results Alpha diversity of geometrid moths was significantly correlated with species diversity patterns in the most common vascular plant families (R² = 0.49) and with plant structural parameters (R² = 0.22), but not with overall floristic diversity. Species turnover of geometrid moths was strongly linked to diversity changes in a range of plant families (40% explained variance), less strongly to changes in vegetation physiognomy (25%), and only weakly to overall floristic diversity (5%). Changes in elevation were a better predictor of both alpha diversity and species turnover of geometrid moths than any principal component extracted from the vegetation data. Main conclusions Vegetation composition, diversity and structure all showed significant correlations with the diversity and species composition of geometrid moth assemblages. Nevertheless, in most cases relationships were indirect, via environmental parameters such as temperature and humidity, which influenced both vegetation and moth fauna. Possible direct links between geometrid diversity and potential food plants were much weaker. The lack of a significant correlation between overall plant species richness and geometrid diversity indicates that tropical geometrid moths may not be very selective in their food plant choice. Accordingly, a clear correlation between floral diversity and herbivore species richness must be regarded as overly simplistic, and the diversity of vascular plants cannot universally be used as a suitable biodiversity indicator for diverse insect taxa at higher trophic levels.     

Biomass harvest of invasive Typha promotes plant diversity in a Great Lakes coastal wetland

Ecological and financial constraints limit restoration efforts, preventing the achievement of desired ecological outcomes. Harvesting invasive plant biomass for bioenergy has the potential to reduce feedback mechanisms that sustain invasion, while alleviating financial limitations. Typha × glauca is a highly productive invasive wetland plant that reduces plant diversity, alters ecological functioning, its impacts increase with time, and is a suitable feedstock for bioenergy. We sought to determine ecological effects of Typha utilization for bioenergy in a Great Lakes coastal wetland by testing plant community responses to harvest‐restoration treatments in stands of 2 age classes and assessing community resilience through a seed bank study. Belowground harvesting increased light penetration, diversity, and richness and decreased Typha dominance and biomass in both years post‐treatment. Aboveground harvesting increased light and reduced Typha biomass in post‐year 1 and in post‐year 2, increased diversity and richness and decreased Typha dominance. Seed bank analysis revealed that young stands (<20 years) had greater diversity, richness, seedling density, and floristic quality than old stands (>30 years). In the field, stand‐age did not affect diversity or Typha dominance, but old stands had greater Typha biomass and slightly higher richness following harvest. Harvesting Typha achieved at least 2 desirable ecological outcomes: reducing Typha dominance and increasing native plant diversity. Younger stands had greater potential for native recovery, indicated by more diverse seed banks. In similar degraded wetlands, a single harvest of Typha biomass would likely result in significant biodiversity and habitat improvements, with the potential to double plant species richness.     

Evaluation of floristic diversity in urban areas as a basis for habitat management

Questions: How can floristic diversity be evaluated in conser‐vation plans to identify sites of highest interest for biodiversity? What are the mechanisms influencing the distribution of species in human‐dominated environments? What are the best criteria to identify sites where active urban management is most likely to enhance floristic diversity? Location: The Hauts‐de‐Seine district bordering Paris, France. Methods: We described the floristic diversity in one of the most urbanized French districts through the inventory of ca. 1000 sites located in 23 habitats. We built a new index of floristic interest (IFI), integrating information on richness, indigeneity, typicality and rarity of species, to identify sites and habitats of highest interest for conservation. Finally, we explored the relationship between site IFI and land use patterns (LUP). Results: We observed a total of 626 vascular plant species. Habitats with highest IFI were typically situated in seminatural environments or environments with moderate human impact. We also showed that neighbouring (urban) structures had a significant influence on the floristic interest of sites: for example, the presence of collective dwellings around a site had a strong negative impact on IFI. Conclusions: Our approach can be used to optimize management in urban zones; we illustrate such possibilities by defining a ‘Site Potential Value’, which was then compared with the observed IFI, to identify areas (e.g. river banks) where better management could improve the district's biodiversity.     

Long‐term seed bank dynamics in a temperate forest under conversion from coppice‐with‐standards to high forest management

Questions: How do changes in forest management, i.e. in disturbance type and frequency, influence species diversity, abundance and composition of the seed bank? How does the relationship between seed bank and vegetation change? What are the implications for seed bank dynamics? Location: An ancient Quercus petraea — Carpinus betulus forest in conversion from coppice‐with‐standards to regular Quercus high forest near Montargis, France. Methods: Seed bank and vegetation were sampled in six replicated stand types, forming a chronosequence along the conversion pathway. The stand types represented mid‐successional stages of stands in transition from coppice‐with‐standards (to high forest (16 plots) and early‐ and mid‐successional high forest stands (32 plots). Results: Seed bank density and species richness decreased with time since last disturbance. Adjusting for seed density effects obscured species richness differences between stand types, but species of later seres were nested subsets of earlier seres, implying concomitant shifts in species richness and composition with time since disturbance. Later seres were characterized by species with low seed weight and high seed longevity. Seed banks of early seres were more similar to vegetation than to later seres. Conclusions: Abandonment of the coppice‐with‐standards regime altered the seed bank characteristics, as well as its relationship with vegetation. Longer management cycles under high forest yield impoverished seed banks. For their persistence, seed bank species will increasingly rely on management of permanently open areas in the forest landscape. Thus, revegetation at the beginning of new high‐forest cycles may increasingly depend on inflow from seed sources.     

Impact of land use on plant biodiversity and measures for biodiversity conservation in the Loess Plateau in China – a case study in a hilly-gully region of the Northern Loess Plateau

The Loess Plateau is a special natural–cultural unit in northern China. Intensive land use in the past has had, and forestation and grass planting at present will have inevitable impacts on plant biodiversity in the Loess Plateau. Based on the analysis of floristic features within three sampling sites with different land use practices and analysis of species richness among different land use types, we discuss impacts of land use on species richness and floristic features in the Northern Loess Plateau. The results drawn from this case study are as follows: (1) It appears that forestation and grass planting have had a positive influence on the local species diversity, but they have contributed little to the native vegetation in terms of conserving its floristic features. (2) Caragana intermedia shrubland, Pinus tabulaeformis forestland, and natural grassland have made important contributions to supporting indigenous species and maintaining local plant biodiversity. (3) There is a significant positive correlation between land use diversity and species richness. These results imply that practicing biodiversity conservation in situ is feasible and the suitable choice for the Loess Plateau. Concrete measures for biodiversity conservation in the area can include setting up small nature reserves and diversifying land use patterns to maintain as much habitat as possible for native vegetation. The artificial Hippophae rhamnoides shrubland should not be further promoted, considering its negative influence on biodiversity conservation.     

A simple multivariate analysis to assess diversity in a complex long-term managed forest area in central Italy

Today wood and nonwood forest resources management meets and often clashes with environment and biological diversity protection. A main problem is to understand relationships between the different roles of forest biodiversity, site, and management parameters. A multivariate statistical analysis has been carried out in order to interpret relationships between some forest biodiversity components and forest inventory data. Several indices of floristic diversity, species abundance, and structural heterogeneity at stand level have been calculated. The different components of forest biodiversity were separated by principal components analysis. Relations between forest biodiversity indices and site and management attributes have been investigated by two multivariate statistical techniques: bivariate correlation analysis and multiple linear regression. Results showed a high correlation between all the investigated components of forest biodiversity and some topographic and/or forest management attributes. Results also gave ancillary information to define sustainable forest management criteria.     

Unravelling mechanisms of short-term vegetation dynamics in complex coppice forest systems

The silvicultural management of coppicing has been very common in deciduous forests in many European countries. After decades of decline of this practice, socio-economic changes might induce a revival valuing the biomass as a resource. New insights in the ecological processes that regulate plant diversity are relevant for a sustainable forest management. While studies on long-term changes are available, the short-term dynamics of the coppice forest understorey has not yet been explored. In this context, it is interesting to evaluate the species compositional changes, including the processes of species turnover and species impoverishment (nestedness) and to investigate the role of plant functional traits. For this purpose, we resampled a chronosequence of complex coppice beech forests of the Central Apennines (Italy) monitoring the short-time species dynamics of five years (i.e. from 2006 to 2011) in three age classes, i.e. post-logged, recovering and old coppice stands (0–16, 17–31 and > 32 years, respectively). In contrast to our expectation, declining species richness appeared only in the recovering stands, while the landscape scale (between-stand) heterogeneity, except for post-logged and recovering stands in 2011, did not change over five years. Significant temporal nestedness was found in each stage of succession. However, the rate of species turnover and species impoverishment do not significantly differ among the three age classes, indicating their constant importance along the forest regeneration after disturbance. Only in the early stage of forest regeneration after coppicing, species compositional changes are reflected by functional changes with surviving understorey species having clonal regeneration traits. Our results suggest an overall landscape-scale stability (and sustainability) of this coppice forest system. We conclude with management indications, highlighting the importance of maintaining the traditional local approach (coppicing with standards in small 0.5–1.0 ha sized management units with a ca 30-year rotation cycle) where active coppice parcels are interspersed by abandoned stands.     

Plant species diversity in remnant grasslands on arable soils in the cropping Pampa

In order to provide a baseline for management decisions, we evaluated vegetation heterogeneity among 38 remnant grasslands located on high agronomic potential soils along a five degree-east–west transect in the cropping Pampa. This extensive region has been cultivated for well over a century, small-scale traditional forms of agriculture were progressively replaced with large-scale industrial forms and its cropped area has more than doubled in the last 25 years, threatening the maintenance of biodiversity associated to productive soils. We characterized the diversity of this grassland patches, identified its main environmental drivers and searched for factors that favor their invasion by exotic plant species. Vegetation samples were analysed through Canonical Correspondence Analysis, proportional distribution of functional groups was compared and regression models were estimated to identify variables associated with exotic species importance. Water availability, determined by climate and soil characteristics, was the main driving factor of floristic heterogeneity in these grasslands. Exotic richness, mostly of Eurasian species, increases toward the east, related to proximity to the entrance port. The functional group of C₄ native grasses seems to be responsible for biotic resistance to invasion. More than 80% of the species recorded during the first vegetation registers in 1930 are still present, while the number of exotics was seven-fold increased. Despite covering small areas as isolated stands, these are hot spots of native biodiversity and must be the object of increasing attention for conservation and restoration in order to protect the biodiversity of an extensive agricultural landscape.     

Floristic composition,site conditions and diversity of poet’s daffodil (Narcissus radiiflorus Salisb.) hay meadows in the Venetian Pre-Alps and outer Dolomites (N-Italy): implications for conservation and restoration

Abstract

Hay meadows are an important component of the alpine landscape, which evolved over millennia of human activities. When traditionally managed, hay meadows support a rich flora and are recognized for high species diversity. However, both intensification and abandonment can lead to a loss of biodiversity in this vegetation. In this paper, the focus was on the hay meadows where Narcissus radiiflorus Salisb. forms white mosaic carpets during the blooming period. This vegetation was studied through 26 phytosociological relevés, taken in the Venetian Pre-Alps and outer Dolomites (Northern Italy). Relevés were numerically classified and analysed in their relationships with site conditions. Moreover, diversity metrics were calculated for detecting the conservation status of hay meadows subjected to different types of disturbance. The results showed that poet’s daffodils’ dominance brings together hay meadows showing a substantial range of floristic and ecologic variation and that part of the stands dominated by Narcissus radiiflorus could be referred to a habitat type regarded as prioritary for nature conservation. Moreover, management-related variations in functional diversity suggested that the best practice recommended for conservation and restoration of this habitat is the continuation of traditional late mowing. This practice will allow preserving both biodiversity and ecosystem functions and services.     

Diversity and floristic patterns of mediterranean grasslands: the relative influence of environmental and land management factors

Managed grasslands are normally ecosystems with high species diversity. They are associated with traditional extensive livestock grazing. Land-use changes, in particular gradual abandonment or grazing intensification, lead to major changes in floristic patterns of these grasslands, some included in priority habitats of the EU Habitats Directive. In order to analyse these patterns of change, Mediterranean grasslands of eastern areas of mainland Portugal were studied aiming to: (1) establish ecological gradients underlying their floristic patterns; (2) examine the relative importance of both environmental and land-use factors on their floristic composition; (3) assess how floristic composition and species richness are affected by land-use factors. Vegetation sampling was carried out from 2008 to 2009 following phytosociological procedures. Canonical Correspondence Analysis was applied. Variation partitioning was used to assess the relative influence of land-use variables. Richness, legumes cover, endemic species and bryophytes cover were compared in four land-management regimes: unmanaged; extensive grazing by sheep; extensive grazing by cattle and sheep; frequent soil tillage. Significant differences were found in floristic and diversity patterns, revealing the importance of grazing as a management tool for maintaining or improving floristic diversity. From our findings slight extensive grazing can contribute to both maintenance of species diversity and to the increase in legumes cover and thus to palatability and economic value of studied grasslands. Interactions between herbivores and grasslands, considering also their influences on soil properties, have an important role in the equilibrium states which promote biodiversity and conservation of the services of these ecosystems.     

The potential contribution of conifer plantations to the UK Biodiversity Action Plan

Summary

The detrimental effects of conifer plantations on open ground habitats have been well catalogued and discussed, but the potential contribution of planted forests to the conservation of woodland biodiversity has not been quantified to the same extent. This quantification is needed urgently to help forest managers fulfil commitments to biodiversity enhancement as outlined in the UK Biodiversity Action Plan, the UK Forestry Standard and the UK Woodland Assurance Scheme (UKWAS). Results are presented from a five-year programme of research aimed at obtaining baseline information on biodiversity in planted forests and evaluating the contribution of planted forests to the conservation of native flora and fauna. Fifty-two plots were surveyed in total, covering a range of different tree crops (Scots pine Pinus sylvestris L., Sitka spruce Picea sitchensis (Bong.) Carr., Norway spruce Picea abies L. and Corsican pine Pinus nigra var maritima (Aitón) Melville) and stand ages (pre-thicket, mid-rotation, mature and over-mature) in three contrasting bioclimatic zones (upland, foothills and lowlands) throughout Britain. Additional plots were established in semi-natural woodland to allow comparisons between the biodiversity of plantations and native stands. Over 2000 species were recorded in total, including 45 Red Data Book species. Planted stands had similar or richer fungal and invertebrate communities to those of the native stands but poorer lichen and vascular plant communities. The latter were strongly affected by shading, dense, mid-rotation Sitka spruce stands having the lowest species counts. In contrast, these stands had a high diversity of mycorrhizal fungi, including a number of rare and threatened species normally associated with native pine wood. Bryophyte species-richness was related more to climate than woodland type, with the wetter upland spruce and native oak stands having the most diverse communities. Compared to the younger planted stands, over-mature planted stands had a higher proportion of species characteristic of semi-natural woodland stands. This related to greater structural diversity and higher deadwood volumes in the over-mature stands. It is concluded that conifer plantations make a positive contribution to biodiversity conservation in the UK and hence to the UK Biodiversity Action Plan. No single stand or crop type provides ‘optimal’ conditions for biodiversity, but the habitat value of plantations could be enhanced by increasing the area managed under alternative systems to clear-felling, such as ‘continuous cover’ and/or non-intervention natural reserves.