Ancient Wood-pastures Research Articles

Formerly coppiced old growth stands act as refugia of threatened biodiversity in a managed steppic oak forest

Forest vegetation is dominated by long-lived species in the tree layer, which facilitates its relatively high inertia and ability to conserve traces of its history in its structure and species composition. Central European lowland forests have been the subject of diverse human use for millennia and some of the present stands still show remnants of historical management forms practised before the onset of modern forestry. In the past decades, biodiversity decline has become a major concern, and restoration of historical uses has been proposed as a nature-friendly alternative for forest management. We explored the consequences of the transformation of an old oak coppice, historically linked to ancient wood pasture system, to oak plantation. We focused on vascular plant species richness and differences in ecological spectra of the plant assemblages, with the goal of evaluating the consequences for biodiversity conservation and identifying possible environmental drivers behind the observed patterns. The study was performed in the best preserved complex of lowland steppic oak forests in the Czech Republic, protected as a Site of Community Importance. We fully inventoried plant species in 135 oak stands classified into three management-age classes: (1) clear-cuts, (2) young growth stands after area-wide site preparation, and (3) old growth stands. For some analyses, old growth stands were divided into those showing signs of past coppicing and the others. We found that species richness was the highest in clear-cuts, the lowest in young growth stands, and intermediate in old growth stands. Clear-cuts showed the highest uniqueness in species composition, with a high share of ruderal species. Young growth stands showed the lowest uniqueness, with a high proportion of competitive species. Old growth stands showed intermediate uniqueness and the coppiced ones had a high share of stress-tolerant species, often of high conservation value. While it is hardly surprising that the establishment of oak plantations has profound effects on biodiversity, we suggest that clear-cutting itself may not be a key issue. Destructive site preparation in clear-cuts, and competition for resources in dense young oak stands are suggested as the main factors threatening the survival of ancient biota of steppic oak forests in our study area. In contrast, continuity of site conditions in formerly coppiced old growth stands facilitates species survival. We suggest that restoration of historical management forms such as coppicing and wood pasture may support this continuity. Where oak planting is still applied, we advise minimising site preparation and applying early thinning of young growth stands.

Understanding human–nature connections through value networks: the case of ancient wood-pastures of Central Romania

Scattered woody vegetation generates multiple socio-economic and environmental benefits to the rural communities. Disregarding values associated with woody vegetation on pastures can decouple individuals from traditional management practices, resulting in the loss of biodiversity-rich farming landscapes. Here we employ semi-structured interviews and network analysis to understand the value networks attributed to scattered mature and large old trees in traditional wood-pastures of Central Romania. In our approach, values connect people to trees as well as other people when all share the same appreciation for trees. Farmers assigned 18 values to the scattered mature and large old trees on wood-pastures. Mature trees were appreciated mainly for their tangible benefits. The removal of a single value (i.e., shade value for livestock) decoupled a large proportion of farmers from the mature tree value network. Conversely, large old trees were appreciated for their socio-cultural values (e.g., identity, history). For these trees, the removal of individual socio-cultural values decoupled a relatively small number of people from the network. We suggest that the adoption of a value network approach to understanding multifunctional farming landscapes such as wood-pastures is important because it allows for (1) the understanding of the connections between people and landscape features (e.g., trees) as well as between people (i.e., through sharing the same values for trees), (2) the inclusion of values in the social–ecological monitoring projects and the understanding of the role of various local initiatives and land ownership forms in shaping the value network, and (3) facilitating the understanding of the circumstances of how formal regulatory policies may influence the multifunctional farming landscape as a social–ecological system.

Diverse Lineages of Candida albicans Live on Old Oaks.

The human pathogen Candida albicans is considered an obligate commensal of animals, yet it is occasionally isolated from trees, shrubs, and grass. We generated genome sequence data for three strains of C. albicans that we isolated from oak trees in an ancient wood pasture, and compared these to the genomes of over 200 clinical strains. C. albicans strains from oak are similar to clinical C. albicans in that they are predominantly diploid and can become homozygous at the mating locus through whole-chromosome loss of heterozygosity. Oak strains differed from clinical strains in showing slightly higher levels of heterozygosity genome-wide. Using phylogenomic analyses and in silico chromosome painting, we show that each oak strain is more closely related to strains from humans and other animals than to strains from other oaks. The high genetic diversity of C. albicans from old oaks shows that they can live in this environment for extended periods of time.

Insect ecology and veteran trees

Insect and veteran trees are important parts of ecosystems and are usually included in ecological studies of forest management. The loss of veteran trees in woodlands and open landscapes would lead to the loss of saproxylic organisms—an important part of biodiversity. Hence, the persistence of many specialized insects depends on the presence of veteran trees scattered in woodlands (e.g. ancient wood pastures, game parks or protected areas), cities, towns and villages (e.g. avenues, parks or chateau parks) or open landscapes (e.g. fishpond dams, solitary trees or fruit orchards). Veteran tree conditions could be fairly well described by three components—diameter, age and microhabitats present. The problem is that diameter belongs to the most studied characteristics, while age and microhabitats, which can be quite complicated to measure, are much less studied. This paper illustrates that, due to this unbalanced use of indicators of veteran-tree conditions, we are still missing some important information on saproxylic species ecology—and sometimes only large trees might be studied, rather than real veterans. Although we already know that veteran trees are essential habitat for a range of saproxylic organisms, there are still gaps in our knowledge of the specific conditions that veteran trees provide. It is vital that these are quantified and understood so that this information can be used to conserve veteran trees and their associated species.

Wood-pastures in a traditional rural region of Eastern Europe: Characteristics, management and status

Wood-pastures are among the oldest land-use types in Europe and have high ecological and cultural importance. They are under rapid decline all over Europe because of changes in land use, tree cutting, and lack of regeneration. In this study we characterized the structure, condition and threats of wood-pastures in a traditional rural region in Romania. Forty-two wood-pastures were surveyed, as well as 15 forest sites for comparison. All wood-pasture sites were described via four groups of variables: condition, management, site, and landscape context. Forest sites were dominated by Hornbeam (Carpinus betulus) and Beech (Fagus sylvatica), whereas wood-pastures were dominated by Oak (Quercus sp.) and various species of fruit trees. Most wood-pastures contained trees classified as ‘ancient’ but no such trees were found in forests. The proportion of dead trees was positively related to forest cover within 300m around the wood-pasture. Models that included management, site and landscape-related variables best explained the prelevance of Oak, Beech, Hornbeam and Pear trees in wood-pastures. Large oaks and hornbeams were more likely to be dead or affected by uncontrolled pasture burning than small oaks and other tree species. Our results show that ancient wood-pastures are common in this rural region, and they may be more common in Eastern Europe than previously thought. There is an urgent need for research, legal recognition and conservation management of wood-pastures as distinct landscape elements for their cultural, ecological and agricultural importance.

The role of rodents in the seed fate of a thorny shrub in an ancient wood pasture

Thorny shrubs play a crucial role for the diversity and dynamics in wood pastures: they protect non-defended plants from large herbivores and thus facilitate tree establishment in the landscape through associational resistance. How thorny shrubs themselves establish in wood pastures – the main bottleneck for a dynamic shifting of grassland – shrub – woodland mosaics – is an essential unanswered question. We studied post-primary dispersal seed fate – i.e. removal, predation, secondary dispersal and survival of seeds after primary dispersal – of the thorny shrub blackthorn ( Prunus spinosa) in an ancient wood pasture in the Netherlands. Blackthorn seeds are primarily dispersed by frugivorous birds and may secondarily be dispersed by scatter-hoarding rodents. We performed two cafeteria-style experiments with blackthorn seeds placed on dishes in the dominant vegetation types. In the first we monitored seed removal in grassland, swards or blackthorn shrubs and determined rodent species abundance by live-trapping. In the second we followed tagged blackthorn seeds under shrubs and in swards to determine seed removal, predation, survival and secondary dispersal patterns. Tagged seeds were retrieved using a metal detector and by visual means. We recorded dispersal direction and distance, vegetation type, seed handling (burial, consumption) and rodent species responsible via bite marks. Seed removal and number of live-trapped rodents differed between vegetation types, with higher removal and rodent captures under shrubs than in swards and grassland. All retrieved seeds were depredated, predominantly by the wood mouse ( Apodemus sylvaticus). Disproportionally high seed numbers were retrieved in the vegetation type where originally placed (shrubs or swards). Our study suggests that rodents play an important role for blackthorn in wood pastures, predominantly as seed predators rather than secondary seed dispersers. Predation is particularly high under blackthorn shrubs, suggesting that primary seed dispersal by birds away from shrubs into grassland or swards is a prerequisite for blackthorn recruitment in wood pastures.

Effects of cattle and rabbit grazing on clonal expansion of spiny shrubs in wood-pastures

Spiny shrubs protect non-defended plants against herbivores. Therefore, they play a role for the diversity in grazed ecosystems. While the importance of these keystone nurse shrubs is presently recognized, little is known about the factors controlling them. This knowledge is required to understand the functioning of grazed ecosystems and for sustainable management. We studied effects of cattle and rabbits on clonal expansion of Prunus spinosa in two ancient wood-pastures in the Netherlands. At each site we set up five blocks in grassland perpendicular to the edges of mature Prunus thickets, each block containing three herbivore treatments: (1) open-to-cattle-and-rabbits, (2) open to rabbits, cattle excluded, (3) cattle and rabbits excluded. We monitored the number and volume of Prunus ramets from 1998 to 2000 and again in 2003, 3 years after exclosure-removal to restore grazing. For 1998–2000 ramet volume, but not ramet number, differed between treatments. Ramet volume was highest when both cattle and rabbits were excluded. Ramet volume did not differ between grazing by rabbits or cattle and rabbits combined, indicating that rabbits alone may be as effective in inhibiting clonal expansion as cattle and rabbits combined. Three years after exclosure-removal ramet number and volume had increased in all treatments. Number of ramets remained unaffected by (former) treatments. Ramet volume remained highest in the former cattle-plus-rabbits exclusion treatment, differing significantly from the ‘open-to-cattle-and-rabbits’ treatment. So, once successfully established during herbivore absence, further expansion is not prevented by cattle and rabbit grazing. This study shows that vertebrate herbivory controls the keystone nurse-shrub in wood-pastures: combined cattle and rabbit grazing, and notably rabbits alone, inhibit expansion. Temporary herbivore absence allows expansion of ramets, which persists after herbivore-reappearance. Sustainable management of wood-pastures should allow spatial-temporal fluctuations of herbivore densities, leading to increased vegetation structure and associated biodiversity.

Ancient oak wood-pasture as a habitat for the endangered tree pipit Anthus trivialis

Ancient wood-pastures are facing a major decline in several European countries. These habitats are of great importance for biodiversity because of their special semi-natural character that increases landscape variability and connectivity. In this paper we examine the habitat preferences of the tree pipit Anthus trivialis in an ancient oak wood-pasture, the Breite Natural Reserve, central Romania, with the aim of identifying the most significant habitat variables correlated with the presence of this species. In this way, we aim to highlight the need for conservation management of both the species and this particular habitat type, which are both declining across Europe. We found that the number of oaks with a diameter at breast height (d.b.h) > 1.27 m (equating to a circumference of 4 m) was the only variable with significant positive effect on the presence of the tree pipit. Shrub cover had significant negative effect on presence. Tree canopy cover, the clumping tendency of trees and distance from forest had no effect on the presence of this species in the study area. Our results show that the habitat requirements for the maintenance of the tree pipit impose the same active management needs as those for the maintenance of the ancient wood-pasture character of the Breite Natural Reserve, namely the control against hornbeam invasion and ensured viability of new oak sapling generations.

Structure and composition of pole-stage stands developed in an ancient wood pasture in central Spain

El Chaparral de Montejo is a woodland area situated in central Spain containing a large group of temperate species that since the Middle Ages has been subject to communal use for grazing like many other European forests. We studied the characteristics of former wood-pasture and the pole-stage stands developed close to ancient trees in three representative stands consisting of Fagus sylvatica , Quercus petraea and Quercus pyrenaica . The Fagus sylvatica stand proved to be the best regeneration site because of its deep soil and greater number of ancient trees, which provided more seeds and tree cover, both favouring the development of seedlings in this stand. However, the poorer soil conditions and the dense layer of herbaceous vegetation in the Quercus pyrenaica stand have inhibited the establishment of the more water-demanding temperate species. It is suggested that past irregular exploitation conducted to a mosaic distribution of forest communities explain the differences in structure and composition found in the three stands studied. The stand occupied by the more xerophilous species, Quercus pyrenaica , was more affected by the reduction of forest productivity in the past. Nowadays the patterns of pole-stage stand diversity reveal the future expected changes. The higher diversity of saplings in the Quercus petraea and Quercus pyrenaica stands reveal better conditions in the understorey than those existing in their early developmental stages, especially for the two shade-tolerant species, beech and holly. On the contrary the lower diversity of saplings in the Fagus sylvatica stand is due to the low light levels in the understorey which gradually cause the disappearance of shade-intolerant species.

Long-term change and implications for the management of wood-pastures: experience over 40 years from Denny Wood, New Forest

Long-term changes in Denny Wood, an ancient wood-pasture in the New Forest, were recorded on two permanent transects. One was located in an unenclosed part of the wood, which remained open to all large herbivores (ponies,deer, cattle). The other was in an enclosed part, which was fenced against livestock (but not deer) from 1870 to ∼1960, after which ponies regained access. Records of trees, shrubs, seedlings and vascular ground vegetation within the transects were made mainly during 1959-1964 and 1996-2001. The unenclosed transect changed greatly. In 1959 it comprised closed beech-oak Fagus sylvatica-Quercus robur forest with abundant holly Ilex aquifolium understorey and small patches of Agrostis lawn or Pteridium aquilinum grazed by moderate numbers of large herbivores. Forty years later this had become an open oak-beech parkland with little understorey. Species-rich lawns and stands of Pteridium had spread extensively, and large herbivores had become far more numerous. Oak survived much better than beech: the larger beech suffered particularly from drought in 1976 and the medium beech from debarking by grey squirrels Sciurus carolinensis. Many beech were cut and removed in a safety/salvage operation in 1981. Holly was reduced mainly by browsing and debarking by ponies and deer. Tree and shrub seedlings became more abundant, but browsing effectively prevented regeneration. The enclosed transect also comprised closed beech-oak-holly forest in 1959. However, the stand was denser and the ground vegetation was more heavily shaded, species-poor and sparser than on the unenclosed transect. Substantial gaps were created during the next 40 years due mainly to the loss of large beech and oak after drought in 1976 and later storms. Rank, species-poor grassland and stands of Pteridium developed mainly below gaps, but many parts remained as closed high forest with little ground vegetation. No dead trees were removed and dead wood volumes remained consistently high. Holly was much reduced, principally due to browsing and debarking by deer and ponies. Grazing almost completely prevented tree regeneration. The implications for grazing of wood-pastures are discussed. Prolonged exclusion of livestock with reduced deer numbers allowed abundant regeneration of trees with holly, but the ensuing dense, closed stand had an impoverished ground flora. Moderate numbers of livestock (both ponies and cattle) and deer kept some grassy glades, but allowed holly to spread. High numbers of livestock (mainly ponies) with deer reduced holly and, where the canopy opened, helped restore herb-rich ground vegetation, aided by the continuity of grazed turf and refuges provided by Pteridium for grazing-sensitive plants. Nevertheless, heavy grazing mainly by ponies prevented tree regeneration for many decades, even in large openings and despite the presence of possible protective features, i.e. spiny bushes, fallen trees, and stands of Pteridium. The widespread failure of regeneration, reduction in underwood and scrub, accelerating mortality and break up of old-growth stands, and damage to young trees by grey squirrels, represents a vulnerable point in the history of New Forest wood-pastures.