Survival, growth, and escape from herbivory are determined by habitat and herbivore species for three Australian woodland plants

To understand how plant communities are structured by herbivory it is essential to investigate the roles of different herbivores and the responses of a variety of plant species in different habitats. We examined the effects of mammalian herbivores on survival and growth of transplanted seedlings of two native trees (Eucalyptus albens and Callitris glaucophylla), and one native grass (Themeda australis) in white box (E. albens) woodlands in eastern Australia over 3 years. Herbivores were manipulated using four fencing treatments that successively excluded livestock, macropods, and rabbits from woodland and grassland (cleared pasture). Survival was highest in the absence of mammalian herbivores and in woodlands, and patterns differed among plant species. Survival of T. australis was low, especially in grasslands, and mortality by overgrowth was common in ungrazed treatments. All plant species were taller in fenced plots, and differences between treatments were greater in grassland. Rabbits and livestock had the greatest influence on C. glaucophylla, while T. australis and E. albens were most affected by livestock and macropods. We used field data to parameterize stage-classified matrix models to predict escape from herbivory (escape height >100 cm) for tree species. Reduced herbivory increased the proportion of individuals reaching escape height after 15 years. Rate of escape was greater in grassland, and this faster growth appeared to counteract much of the negative impact of herbivores. While T. australis was unable to escape herbivory, larger, ungrazed individuals were more likely to flower and therefore contribute to the maintenance of the population. Our results show that habitat and herbivore species strongly influence the effect of herbivory on vegetation.     

Evaluation frameworks and conservation system of Latvian forests

Since the 1990s the forest conservation system in Latvia has developedin two parallel trends. This reflects both traditional application ofcentral European phytosociology by explicit forest communities (at least 19 associations inLatvian forests) and the recently appreciated method of key-habitats in forests.It consists of two attributes: indicator species–habitat specialists andcertain abiotic structures whose persistent presence on the spot is limited byintactness, time-scale and natural disturbances. Following the interpretationmanual of habitats in the European Union, eight forest habitats deserve particularconservation in Latvia. Altogether 8% of Latvian forests are formally protected,although only 1.5% meet the World Conservation Union Category 1where all human intervention must be excluded or minimized. Original analysis ofLatvian forest communities by their phytosociological standard and a comparisonwith similar assemblages elsewhere suggest that four forest groups deserveall-European conservation priority in Latvia because of intactness and largestands still survived or because of narrow distribution area. These are:Alnus glutinosa–Betula spp.–Fraxinus excelsior wetlands (ca. 3000 ha invarious formal reserve networks), northern outposts of mixed riverine hardwoodforests on the bank slopes and in semi-permanently moist ravines (ca. 240ha in reserves), floodplain and riverine Quercusrobur relic woodlands in eastern Latvia (ca. 120 ha inreserves) and dry Fennoscandian–Baltic Pinussylvestris woodlands on dolomites and limestones (no areas formallyprotected by law yet). Preliminary inventory of woodland key-habitats suggeststhat only 3% of Latvian forests can meet the desired criteria. This method,based on 53 indicator species indicating certain habitat properties and 25abiotic structures and stand features, has been found a valuable tool inforestry practice to evaluate the forest before any logging takes place and tomonitor spatial changes of biodiversity.     

An indirect gradient analysis of the ecological relationships between ancient and recent reiverine woodlands to the south of Bruges (Flanders,Belgium)

Summary Riverine forests to the south of Bruges were sampled according to the principles of the Braun-Blanquet approach. Cartographic data allowed a distinction between old (pre-1775) and recent (planted after 1775) woodland. Using a chi-square criterion and/or a Fisher exact probability test, the association of species with the two historical types of woodland was tested. Corylus avellana, Lamium galeobdolon, Primula elatior, Anemone nemorosa, Deschampsia cespitosa and Thamnium alopecurum are confined to ancient woodland. Glechoma hederacea, Prunus padus, Lysimachia nummularia, Ribes rubrum and Lychnis floscuculi have a significant affinity for recent woods.R-type prineipal components analysis produced an effective ordination of species and relevés. Interpretation of the scatter diagrams was performed using indicator values for the species and some environmental parameters for the relevés. Two major gradients were detected: the first one is the coenocline from wet, basic clay soils towards drier, more acidic, sandy soils. Anthropogenic dynamics, through the general management which effects the micro-climate in the wood, particularly the relative light intensity, has been recognized as the second ecological parameter.The potential natural vegetation of the valleys is thus determined primarily by soil texture and soil moisture, and secondarily by former land use (and age). It takes at least 200 years before old woodland species start to colonize recent woodland.We are much indebted to Prof. Dr. P. Van der Veken for his criticism of the manuscipt and to B. Kuziel en G. Dujardin for reviewing the English text.Nomenclature follows De Langhe et al. (1978) for vascular plants and Margadant (1973) & Margadant & During (1973) for bryophytes.Dedicated to the memory of Dr. Ir. G. Sissingh (1912–1979).This study was supported by a grant from the Instituut tot aanmoediging van het Wetenschappelijk Onderzoek in Nijverheid en Landbouw and since 1 October 1979 from the Nationaal Fonds voor Wetenschappelijk Onderzoek.     

Benefits of habitat restoration to small mammal diversity and abundance in a pastoral agricultural landscape in mid-Wales

Changes in agricultural practice are predicted across the UK following agricultural reform driven by government policy. The suitability of agri-environment schemes for many species is currently debated because limited quantitative data are collected. In order to understand the changes to biodiversity due to agri-environment schemes, there is a need for studies to not just compare biodiversity and species composition in and out of agri-environment areas, but to factor in the influence of temporal habitat changes. In this study, we investigate the suitability of an agri-environment initiative to support and enhance a small mammal fauna among pastoral hill farms in mid-Wales. Grazed and ungrazed woodlands, riparian habitats, and broadleaf plantations, were compared for small mammal abundance and diversity following a trapping study. Mammal diversity was similar across habitats, though abundance varied significantly. A principle component analysis identified that mammal abundance clustered into three main habitat groups separated by seral stage (early, mid, late). No relationship between mammal abundance and stock grazing was found. A canonical correspondence analysis confirmed that vegetation structure was important in explaining the distribution of captures of mammal species across the landscape. The results for habitat type, and habitat context, suggest that a mix of vegetation seral stages, reflecting a varied vegetation structure, is important to maintain small mammal diversity and abundance across the study area. Heterogeneity in structural diversity at the landscape scale is important to maintain a variety of ground-dwelling mammal species, and particularly because trends in countryside surveys show that woodlands are skewed towards late seral stages. Habitat heterogeneity can be maintained because the hill farms neighbour each other, and the farmers co-operate as a group to manage the landscape. Habitat diversity is therefore possible. These results help us to advocate, and anticipate, the benefits of groups of farms within a landscape.     

Past vegetation dynamics of Vltavský luh, upper Vltava river valley in the Šumava mountains. Czech Republic

Six pollen diagrams from peat bogs in the Vltavsky luh (upper Vltava river valley) provide new information about vegetation reconstruction, woodland dynamics, and local development of mires during the Late-glacial and Holocene. Vegetation development began in the Oldest Dryas/B?ling with open park plant cover. In the Aller?d, woodland with Pinus and Betula developed, and in the Younger Dryas there was a steppe tundra with plants of open habitats. In the Pre-boreal, woodland tundra grew. In the Boreal, Corylus spread, and a major expansion of Picea began in the early Boreal. Picea spread during the Atlantic probably by two different migration routes. Fagus immigrated earlier than in the Bayerischer Wald and Oberpf?lzer Wald in the adjoining parts of Germany, and had its major expansion in the early Atlantic. Abies expanded in the late Atlantic. The great abundance of Abies in this area is remarkable, forming Abies or Abies-Fagus woods in less extreme habitats. Human occupation started in the Sub-boreal, as shown by both archaeology and palynology. However, human impact is recognized from anthropogenic indicators which appear in the early Atlantic. At the end of the later Sub-atlantic the development of natural woodland was interrupted by plantation of Picea according to historical and palynological evidence. Received November 13, 2000 / Accepted July 7, 2001     

Spatial analysis of eucalypt dieback at Coranderrk,Australia

Abstract. The cause of tree disease in any location is difficult to diagnose because of the multiplicity of potential causes. Spatial analysis provides useful evidence on the significance, scale and shape of patterns for disease diagnosis. This study explores the causes of dieback through spatial analysis of tree health at Coranderrk Reserve, an example of an important conservation reserve on the urban fringe of Melbourne, Victoria. Ca. 200 trees were sampled at two sites and measured for position, diameter and height in each of two different community types. An index of tree health was developed, and each tree was assigned a value of health. Dead trees were categorized based on state of decay. Correlograms using Moran's I found significant spatial structure at both study sites. The study employed a method of analysis that compares the spatial patterns in dead and living trees. When all dead trees were eliminated from the analysis, significant spatial pattern was found only at one site. The spatial structures obtained were compared with those expected from the different possible causes of tree dieback. Some potential explanations were eliminated. The results illustrate how spatial analysis may make useful contributions to disease diagnosis if employed systematically together with other modes of investigation.     

Vegetation of the woodland‐steppe transition at the southeastern edge of the Inner Mongolian Plateau

Abstract. The vegetation of the woodland‐steppe transition in southeastern Inner Mongolia, where the East Asian monsoon climate reaches its northwestern edge, is described and analysed in this paper. The communities are classified in a phytocoenological way. 12 major types of woodland, shrubland, meadow, fen, open woodland and steppe are differentiated and described on the basis of 133 phytosociological relevés. Detrended Correspondence Analysis shows that precipitation plays a crucial role in the distribution of grassland communities while woodland and shrubland communities are controlled by both warmth and humidity conditions. Four vegetation zones can be distinguished. From the woodland to the woodland‐grassland zone, the temperature decreases and the precipitation increases with increasing altitude, which leads to the conditions suitable for the meadow and fen communities. In the direction of the woodland‐steppe zone the temperature increases while the precipitation decreases with the gradual lowering of the altitude; the steppe communities form a matrix while the woodlands have a patchy distribution. From the woodland‐steppe to the steppe zone, the precipitation rather than temperature decreases; as a result the woodland communities disappear gradually. On a local scale, geomorphologic conditions determine the vegetation pattern of the study area. Due to the existence of a sandy substrate different woodland types occur together in the woodland‐steppe transition. The local distribution of woodland and steppe communities is dependent on slope conditions. In addition, human disturbance has also influenced the composition of plant communities.     

Structural features of fragmented woodland communities affect leaf litter decomposition rates

Disruption to the physical structure of plant communities by habitat fragmentation can change microclimates, so leaf litter decomposition rates, being dependent on temperature and moisture, may also be affected. Similarly, smaller-scale structural features of plant communities can modify microclimates, and so may produce distinctive spatial patterns in decomposition rates. We investigated the effects of three types of structural feature having the potential to alter litter layer microclimates: fragmentation-induced modification that diminishes with distance from remnant edges (edge-core); concentric zones of locally modified conditions imposed by individual trees (Belsky–Canham); and highly localised abiotic modification collectively imposed by herbaceous plants (ground cover). We conducted a litter bag experiment in woodland remnants, testing whether the observed spatial variability in litter decomposition was attributable to one or more of these three structural features. The data provided the strongest support for the Belsky–Canham hypothesis, and the least support for the ground cover hypothesis. However, the hypotheses were not mutually exclusive, for each explained a component of the observed variability not explained by either of the other two. Proximity to remnant edge, proximity to trees, canopy light penetration, and ground cover density each explained part of the observed variability between plots. Decomposition rates did not differ with remnant area per se, for the effects of fragmentation were weak, and differed with cardinal direction. In contrast, the effects of individual trees were much stronger, and accounted for most of the between-plot variability. We found that litter decomposition rates in small remnants are only weakly affected by fragmentation, and we consider that the contributions of small remnants to landscape-scale functioning warrant closer attention.