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This study deals with population dynamics of Cirsium rivulare (brook thistle) present in a meadow that undergoes succession as a result of former disuse. The effect of the following in the succession, currently dominant clonal species and necromass on the performance of the brook thistle population (presence, size of clusters and reproduction) was investigated. The regression stage, the Cirsium rivulare population had attained after mowing, was discontinued. Different kinds of influence from the contiguous species on the brook thistle population could be identified. In the case of Filipendula ulmaria and Carex cespitosa , Cirsium rivulare clusters were found to be present on the edge of the dominant patches. In case of Carex acutiformis patches brook thistle ramets did not form clusters but were present among the sedge ramets. No Cirsium rivulare ramets were found in Phragmites australis and willow ( Salix cinerea , S. pentandra and S. aurita ) patches. The highest number of generative brook thistle ramets were observed in a Carex acutiformis patch, whereas the highest number of inflorescences on the shoots of the analysed species were identified in the patch dominated by Filipendula ulmaria . Experimental vegetation gaps were created in patches dominated by various species to determine the effect of necromass on the presence of Cirsium rivulare seedlings. A considerable rise in the number of Cirsium rivulare seedlings was noted in Carex acutiformis and Filipendula ulmaria patches following necromass removal in comparison with plots containing necromass. On the other hand, removing the necromass and foliage did not contribute to an increase in the numbers of brook thistle seedlings in the patch dominated by Cirsium rivulare itself.

We investigated the effects of invasion by introduced grey willow (Salix cinerea) on beetle communities within four wetland vegetation types: native vegetation, native vegetation following grey willow removal, native vegetation undergoing grey willow invasion and dense grey willow-dominated vegetation. In total, 1505 beetles from 90 species were collected using modified Malaise traps. Native wetland vegetation had significantly lower beetle species richness than willow-dominated vegetation and was dominated by herbivores, whereas detritivores characterised willow-dominated vegetation. Beetle abundance was highest in the willow-dominated vegetation and mostly comprised detritivores. In contrast, beetle abundance was lowest in native wetland vegetation, but had even proportions of herbivores and detritivores. Native wetland vegetation had a high proportion of native beetles present. As grey willows invaded, introduced beetles became more common. The beetle community composition differed significant...

Structured decision making and value-of-information analyses can be used to identify robust management strategies even when uncertainty about the response of the system to management is high. We used these methods in a case study of management of the non-native invasive species gray sallow willow (Salix cinerea) in alpine Australia. Establishment of this species is facilitated by wildfire. Managers are charged with developing a management strategy despite extensive uncertainty regarding the frequency of fires, the willow's demography, and the effectiveness of management actions. We worked with managers in Victoria to conduct a formal decision analysis. We used a dynamic model to identify the best management strategy for a range of budgets. We evaluated the robustness of the strategies to uncertainty with value-of-information analyses. Results of the value-of-information analysis indicated that reducing uncertainty would not change which management strategy was identified as the best unless budgets increased substantially. This outcome suggests there would be little value in implementing adaptive management for the problem we analyzed. The value-of-information analyses also highlighted that the main driver of gray sallow willow invasion (i.e., fire frequency) is not necessarily the same factor that is most important for decision making (i.e., willow seed dispersal distance). Value of-information analyses enables managers to better target monitoring and research efforts toward factors critical to making the decision and to assess the need for adaptive management. Resumen: La toma de decisiones estructurada y el analisis del valor de la informacion pueden ser utilizados para identificar estrategias de manejo robustas aun cuando la incertidumbre sobre la respuesta del sistema al manejo es alta. Utilizamos estos metodos en un estudio de caso del manejo de la especie exotica invasora Salix cinerea en Australia alpina. El establecimiento de esta especie fue facilitada por incendios. Los manejadores son responsables del desarrollo de una estrategia de manejo no obstante la gran incertidumbre relacionada con la frecuencia de incendios, la demografia de S. cinerea y la efectividad de las acciones de manejo. Trabajamos con manejadores en Victoria para llevar a cabo un analisis de decisiones formal. Utilizamos un modelo dinamico para identificar la mejor estrategia para una gama de presupuestos. Evaluamos la robustez de las estrategias a la incertidumbre con analisis del valor de la informacion. Los resultados del analisis del valor de la informacion indicaron que la reduccion de la incertidumbre no cambiaria la estrategia de manejo identificada como la mejor a menos que los presupuestos incrementaran sustancialmente. Este resultado sugiere que la implementacion de manejo adaptativo tendria poco valor para el problema que analizamos. El analisis del valor de la informacion tambien destaco que el factor principal de la invasion de S. cinerea (i.e., frecuencia de incendios) no necesariamente es el mismo factor mas importante para la toma de decisiones (i.e., distancia de dispersion de semillas). El analisis del valor de informacion posibilita a los manejadores a realizar un mejor monitoreo y esfuerzos de investigacion enfocada a factores criticos para la toma de decisiones y para evaluar la necesidad de implementar manejo adaptativo.

The Hebridean island of Coll has almost certainly been predominantly treeless for at least two millennia; it was certainly largely deforested when the first surviving written description of the island was made in the sixteenth century. A survey of the surviving native trees, shrubs and lianes carried out between 1997 and 2011 showed that only Salix aurita is present in any quantity, with all other species being reduced to small, relict stands or scattered individuals. Juniperus communis (at least 650 bushes), Populus tremula (450 trees) and Sorbus aucuparia (121 trees) are the commonest of these species and represent contrasting strategies, with P. tremula present as long-lived suckering clones and the others as freely seeding but probably short-lived individuals. Betula pubescens (42 trees), Hedera helix (50 plants), Corylus avellana (17 trees), Quercus spp. (11 trees) and Salix cinerea (4 stands) are the rarest surviving native species. Historical records indicate a decline since the 1930s of Be...

The blue willow beetle, Phratora vulgatissima , is considered to be the most damaging herbivorous pest in Salix short-rotation coppices throughout Europe. The braconid parasitoid Perilitus brevicollis is an important natural enemy of Phratora . As several different Salix species are used in coppices, I investigated the bottom–up (tritrophic) effects of Salix on the parasitoid. Three host plants were studied: the introduced fast-growing S. viminalis , which is highly susceptible to the beetle; S. dasyclados , which is introduced and moderately-resistant to the beetle; and the native slow-growing Salix cinerea , which is not currently used in coppices. The identity of the host-plant species had significant effects on parasitoid larval development time; parasitoids developed rapidly on the susceptible S. viminalis and slowly on the moderately resistant S. dasyclados . Increased development time resulted in reduced adult longevity. Host-plant species identity also affected larval survival; 57%, 64%, and 49% of the parasitoids successfully completed larval development in beetles fed S. viminalis, S. cinerea , and S. dasyclados , respectively. Parasitoid development was also correlated with the body size of their beetle host, but this effect was independent of the identity of the host-plant species. The results of this study suggest that the parasitoid has higher survival and growth rates when it parasitizes beetles feeding on the common coppice species S. viminalis , but the performance of the parasite is reduced when the beetle feeds on the moderately-resistant S. dasyclados . Conversely, the omnivorous biocontrol agents sometimes used in these systems appear to perform better on S. dasyclados compared to S. viminalis . The results of this study suggest that Perilitus parasitoids and omnivorous beetle predators may provide complementary protection to Salix and therefore be useful in coppice management.

An attempt was made to identify the major risks to the population of Betula humilis Schrk. existing in a small isolated transitional peat bog near Lake Bikcze, in the Łęczna-Włodawa Lakeland. The biometric features of 40 Betula humilis individuals were measured as well as the growth of shoots, flowering and fruiting were observed. Habitat conditions were characterized by making measurements of selected abiotic and biocenotic environmental factors. The obtained results allowed us to identify two main threats to the proper functioning of the study population. The first one is the possible loss of genetic identity of the species as a result of probable ongoing introgression by the potential crossing of Betula humilis with other species of the genus Betula, which are numerous in the flora of the studied area. Another threat is a change in habitat conditions (mainly light and water conditions), which is due to the accelerated secondary succession manifested by the expansion of common species such as Salix cinerea, Betula pendula, and Phragmites australis.

The paper presents results of a study on the response of species growing in experimental gaps in the patches dominated by Carex acutiformis, C. cespitosa and Salix cinerea. The study was performed in a meadow area subjected to the process of succession in the Reski Range in the Białowieski National Park. Four patterns of seedlings recruitment in the experimental gaps were distinguished: pattern I - great number of seedlings with high richness of species, pattern II - great number of seedlings with low richness of species, pattern III - low number of seedlings with great richness of species and pattern IV - low number of seedlings with low richness of species.

Several experiments evaluating the susceptibility of aquatic and wetland weeds to triclopyr TEA were carried out using potted plants Seedlings of grey willow (Salix cinerea) alder (Alnus glutinosa) and purple loosestrife (Lythrum salicaria) and cuttings of crack willow (S fragilis) primrose willow (Ludwigia peploides) water celery (Apium nodiflorum) water cress (Nasturtium officinale) and monkey musk (Mimulus guttatus) were collected in the field and grown in cultivation At least 2 months after potting up triclopyr TEA was applied to run off at rates between 025 and 5 v/v This resulted in excellent control of all weeds at all rates except for purple loosestrife which was not controlled well at the lowest rate

To circumvent the inherent problem of discriminating between the cost of losing photosynthetic tissue and the cost of producing an inducible defence, the growth response of herbivore-damaged plants was compared with plants damaged mechanically to the same extent but without eliciting the defence. Two experiments were conducted, studying the response of willows (Salix cinerea) to damage by adult leaf beetles (Phratora vulgatissima). In the first experiment, willows produced new leaves with an enhanced leaf trichome density 10-20 d after damage, coinciding in time with the feeding of beetle offspring. The response was relaxed in foliage produced 30-40 d after damage. In the second experiment, which also included mechanical damage, willows exposed to beetle feeding showed an increase in leaf trichome density of the same magnitude (> 70%) as in the first experiment. The cost of producing the defence was a 20% reduction in shoot length growth and biomass production. Willows exposed to mechanical damage had an 8% reduction in shoot length growth compared with control plants, that is, a cost of leaf area removal. The results are the first quantitative estimates of the cost of a plant defence induced by natural and low amounts (3.3%) of herbivory.

Metal concentration of plants growing on contaminated soils among other factors may depend on changes in the hydrological regime of the soil. Foliar and stem metal concentrations in Salix cinerea (grey sallow) were measured in 2 consecutive growing seasons on a submerged sediment-derived soil that underwent gradual terrestrialisation. Foliar and stem cutting concentrations for Cd, Zn and Mn increased on plots that were submerged during the first year, but emerged in the second year of monitoring. The litter layer was sampled under the shrubs of a plot with a recent abrupt change in hydrological regime and on the reference plot. It was separated in three size fractions through sieving. Analysis of the litter fractions suggested that Cd and Zn concentrations remained constant during fragmentation. However, Cr, Cu, Ni and Pb concentrations increased, which was attributed to adhesion of mineral soil particles on the fine fraction. After correction for the metal content in the mineral fraction, an increase in Cd, Mn and Cu concentration during fragmentation of the organic part of the litter layer was observed for the polluted plot. Net litter layer decomposition rate was low, which may indicate low colonisation by the decomposing community. Terrestrialisation resulted in higher Cd, Mn and Zn uptake by willows. The deviant litter layer metal concentrations for Cd, Zn and Mn and low decomposition rate must be further monitored. Feasibility of measures aiming at re-establishing wetland conditions for the dredged sediment landfill must be considered.

Herbivorous insects are influenced by both 'bottom-up' forces mediated through host plants and 'top-down' forces from natural enemies. Few studies have tried to evaluate the relative importance of the two forces in determining the abundance of insects. The leaf beetle Phratora vulgatissima Linnaeus sometimes occurs at high densities and severely damages the willow Salix cinerea in forest habitats. For willows growing in open agricultural landscapes (farmland S. cinerea), the leaf beetle generally occurs at low densities and plants receive little damage. The purpose of the present study was to evaluate the relative importance of host plant quality and natural enemies behind the observed difference in P. vulgatissima abundance. Female egg-laying and larval performance (growth and survival) were studied on caged willow branches in the field to investigate if plant quality differs between S. cinerea trees growing in forest and farmland habitats. The survival of eggs exposed to natural enemies was examined to see if predation could explain the low abundance of leaf beetles on farmland willows. The results indicated no difference in plant quality; female egg laying and larval performance did not differ between the forest and the farmland. However, heteropteran predators (true bugs) were more abundant, and the survival of eggs was lower, on plants in the farmland habitat than in the forest habitat. The data suggest that the low abundance of P. vulgatissima on farmland willows could not be explained by a poor quality of plants, but more likely by high predation from heteropterans.

Plant characteristics, such as leaf structure or hairiness, are important for the movement and attachment of insects. It has been suggested that increased trichome density on new Salix cinerea L. (Salicaceae) leaves, produced after grazing by the willow leaf beetle Phratora vulgatissima L. (Coleoptera: Chrysomelidae), function as an inducible defence against the beetle and especially its larvae. Here we studied whether and how two of the main natural enemies of P. vulgatissima , viz., Anthocoris nemorum L. (Heteroptera: Anthocoridae) and Ortothylus marginalis L. (Heteroptera: Miridae), were influenced by trichome density on S. cinerea leaves. The effect of trichome density on these two predators was studied on plants with different trichome densities, comparing natural enemy efficiency, measured as number of P. vulgatissima eggs consumed or larvae missing and/or killed. To obtain different trichome densities, cuttings of several different clones of S. cinerea were used. In the experiment using eggs as prey, an increase in trichome density was, in addition, induced through leaf beetle defoliation on half of the plants of each willow clone. Furthermore, a field study was performed to investigate whether trichome density was correlated with natural enemy abundance. The results indicate that neither the efficiency of these two natural enemies in the greenhouse, nor their abundance in the field was influenced by trichome density. A well-known behavioural difference between the two predator species could probably account for the higher disappearance of larvae after exposure to the more active predator. These findings are relevant for the development of pest management programs, not least because the enemies are polyphagous predators. It is concluded that an induced increase in leaf hairiness in willows in response to leaf beetle grazing could be a plant resistance trait worthy of further study in this system, because no negative effects on the main natural enemies were observed.

Several authors suggest that a hydrological regime aiming at wetland creation is a potential management option that favours reducing bioavailability for metal-contaminated sites. The hydrological conditions on a site constitute one of the many factors that may affect the availability of potentially toxic trace metals for uptake by plants. Bioavailability of Cd, Mn and Zn on a contaminated dredged sediment landfill (DSL) with variable duration of submersion was evaluated by measuring metal concentrations in the wetland plant species Salix cinerea in field conditions. Longer submersion periods in the field caused lower Cd and Zn concentrations in the leaves in the first weeks of the growing season. Foliar Cd and Zn concentrations at the end of the growing season were highest on the initially flooded plot that emerged early in the growing season. Foliar Zn concentrations were also high at a sandy-textured oxic plot with low soil metal concentrations. Zn uptake in the leaves was markedly slower than Cd uptake for trees growing on soils with prolonged waterlogging during the growing season, pointing at a different availability. Zn availability was lowest when soil was submerged, but metal transfer from stems and twigs to leaves may mask the lower availability of Cd in submerged soils. Especially for Cd, a transfer effect from one growing season to the next season was observed: oxic conditions at the end of the previous growing season seem to determine at least partly the foliar concentrations for S. cinerea through this metal transfer mechanism. Duration of the submersion period is a key factor for bioavailability inasmuch as initially submerged soils emerging only in the second half of the growing season resulted in elevated Cd and Zn foliar concentrations at that time.

1 Willows are frequently attacked and defoliated by adult leaf beetles (Phratora vulgatissima L.) early in the season and the plants are then attacked again when new larvae emerge. The native willow Salix cinerea has previously been shown to respond to adult grazing by producing new leaves with an increased trichome density. Subsequent larval feeding was reduced on new leaves. This type of induced plant response may reduce insect damage and could potentially be utilized for plant protection in agricultural systems. 2 Here, we investigated if the willow species most commonly used for biomass production in short rotation coppice, Salix viminalis, also responds to adult beetle grazing by increasing trichome density. Larval performance and feeding behaviour on plants previously exposed to adult beetles was compared with that on undefoliated control plants in a greenhouse. 3 We found an overall decrease in trichome density within all the plants (i.e. trichome density was lower on new leaves compared to that for older basal leaves on S. viminalis). However, leaves of beetle defoliated plants had a higher trichome density compared to control plants. Larval growth and feeding was not affected by this difference between treatments. Larvae appeared to remove trichomes when feeding on S. viminalis, a behaviour that might explain the lack of difference between treatments.

Woodland colonization on wetlands is considered to have a detrimental effect on their ecological value, even though detailed analysis of this process is lacking. This paper provides an evaluation of the ecological changes resulting from succession of poor fen (base-poor mire) to willow wet woodland on Goss Moor NNR in Cornwall, UK. Different ages of willow carr were associated with eight understorey communities. During willow colonization, in the ground flora, there was a progressive decrease in poor fen species and an associated increase in woodland species, which appeared to be related to an increase in canopy cover and therefore shade. The most diverse community was found to be the most recent willow and was dominated by poor fen species. The oldest willow was the second most diverse and was associated with a reduction in poor fen species and an increase in woodland species. Architectural features were used successfully to as- sess the general condition and structure of willow. Tree height and DBH were identified as useful parameters to accurately assess willow age in the field. The implications of active intervention to remove willow in order to conserve the full range of communities within the hydrosere are discussed.

To analyze the rhizosphere bacterial communities in wetlands, the total lipid content was extracted from a peat soil and 4 abundant wetland plant roots ( Typha angustifolia L., Salix cinerea L., Carex pseudocyperus L., Thelypteris palustris Salisb.). The separated phospholipid fraction was further fractionated and deriva­tized prior to gas chromatography-mass spectrometry (GC-MS) measurement. In the evaluation only the bacteria-specific fatty acids were used in order to neglect fatty acid information derived from plant root cells. Based on these analyses, a high level bacterial concentration was demonstrated in the rhizosphere, and the relative occurrence of aerobe and anaerobe, Gram positive and negative bacteria, methanotrophs, sulphate reducers and Actinobacteria was determined. Through the PLFA analysis the study of bacteria regardless of culturability was possible.

Plant sex effects on herbivores are well studied, but little is known about these effects on predators and predator-herbivore dynamics. Here we take a holistic approach to study, simultaneously, plant sex effects on herbivore and predator preference and performance, as well as population densities and predation pressure in the field. For dioecious Salix cinerea (grey willow) we found that male plants represented higher host plant quality than females for an omnivorous predator (Anthocoris nemorum, common flower bug), while host plant quality for its herbivorous prey (Phratora vulgatissima, blue willow beetle) was not sex-biased. The herbivore strongly preferred the host plant sex (female) that was suboptimal for the predator, which in turn followed its prey to female plants, leading to plant-sex-biased predation. These results provide new insight into the far-reaching effects of plant sex on insect communities, and open up novel opportunities for improving biocontrol of the herbivore in Salix short rotation coppice.

The possible roles of plant quality (vigor) and natural enemies in the development of a localized out-break of the leaf beetle Galerucella lineola (Coleoptera: Chrysomelidae) in a stand of Salix cinerea were investigated. Caged and uncaged larvae on six bushes in the outbreak area were compared with caged and uncaged larvae on six bushes in an adjacent nonoutbreak area in terms of performance. In 1997, when the studies were performed, the natural density of the insect (beetles plus eggs) was six times higher in the outbreak area compared with the nonoutbreak area. Even though the vigor (measured as shoot length) of bushes in the outbreak was 72% higher than that of bushes in the nonoutbreak area, we found no difference between areas in the performance (survival, developmental time, pupal weight) of caged larvae or in the willingness of caged females to lay eggs. Among larvae exposed to natural enemies, the disappearance rate was significantly higher in the nonoutbreak area. The density of generalist predators was significantly higher in the nonoutbreak than in the outbreak area. We conclude that differences in plant quality, despite the observed difference in plant vigor, could not explain the observed difference in beetle density between areas. Lower predation pressure in the outbreak area could, however, not be excluded as a possible reason for the higher density of leaf beetles in this area.

SUMMARY The association between willow (Salix) and rust (Melampsora) is highly specific. Willows named Salix burjatica, S. dasyclados (S. x dasyclados) and S. x calodendron are important in renewable-energy plantations in the UK and western Europe. There has been much controversy over their origin, species status and nomenclature. It has been suggested that they have originated from hybridization between. S. caprea, S. viminalis and S. cinerea. In the present work, 59 willow clones were investigated through morphological examination and detached leaf inoculation using willow differentials, for their association, in southwest England, with M. capraearum and three pathotypes of Melampsora epitea (Me-A, B and C). M. capraearum was found on all clones of S. caprea and its hybrids with S. aurita; Me-A on all S. viminalis clones; Me-B on wild S. cinerea, S. x calodendron, S. x dasyclados 'De Biardii 445' and S. 'Spaethii'; Me-C on all S. burjatica clones and most S. x dasyclados clones. Both M. caprearum and Me-A infected all S. x sericans (S. caprea x viminalis) clones and S. x dasyclados 'LA041/03'. We suggest that S. x dasyclados 'LA041/03' should be treated as S. x sericans (S. caprea x S. viminalis); S. burjatica, S. dasyclados and S. x dasyclados as synonyms; S. x dasyclados 'De Biardii 445' as S. x calodendron 'De Biardii 445'; and S. 'Spaethii' as S. x calodendron 'Spaethii'.

The A5 London to Holyhead trunk road suffers from large and varied settlements at Pant Dedwydd where it crosses a geotrophic peat bog developed on the glacial drift that overlies bedrock of Silurian Denbigh Grits Group. Recent carriageway settlements have created an undulating profile over a 100 m stretch, restricting forward visibility and posing recurring and persistent difficulties for highway maintenance. The highly compressible peat underlies almost 400 m of highway, ranges up to 7 m deep and a typical profile consists of an upper sphagnum peat layer and a basal reedy, woody and sedge grass peat. The highway was originally constructed by Thomas Telford in 1819 as a low floating embankment over the organic terrain. Increases in traffic over the intervening period together with successive asphalt overlays have resulted in a history of major repairs and although records are incomplete it is likely that the carriageway is now over 2 m thick over parts of the bog. Comprehensive geological investigations carried out to characterize the peat deposit included dynamic probe holes, boreholes and a trial pit. No unusual subsurface conditions were identified. However, scrub willow or grey sallow (Salix cinerea) was observed growing in spiraea thickets alongside the deepest hollows in the highway. The willows may contribute to the road subsidence by extraction of water from the peat beneath the carriageway. Accordingly, removal of the scrub willow and conventional re-grading of the carriageway have been recommended to correct the existing problem.

The removal of ammonium-nitrogen (NH 4 -N) from groundwater flowing through a grey willow (Salix cinerea) and native raupo (Typha orientalis) lake edge wetland was investigated over 10 mo. Monthly groundwater sampling showed that more than 95% of incoming NH 4 -N was removed by the wetland. Laboratory assays found that the potential for NH 4 -N removal by nitrification and subsequent denitrification was significantly higher in the organic surface sediments than in deeper, sandy, root zone sediments. In a laboratory 15 N-tracer experiment, Salix cinerea and Typha orientalis readily assimilated NH 4 -N from the root zone and were found to enhance the natural diffusion of NH 4 -N up through the organic sediment layer and into the overlying water. Estimated rates of removal of NH 4 -N by coupled nitrification-denitrification and plant assimilation were 8 to 9 mg of N m -2 d -1 and 9 to 46 mg of N m -2 d -1 , respectively. Assimilated N, returned to the overlying water-sediment surface via litter fall may be subject to sequential mineralization, nitrification, and denitrification, resulting in gaseous N loss. Sixty-five percent of the 15 N in Salix leaf litter was transformed in such a way. The results of this study indicate that plants play a central role in the NH 4 -N processing capacity of wetlands. The relevance of our findings to constructed wetland design is discussed.

The impact of different concentrations of ambient CO2 on the stomatal density and index of Salix cinerea are investigated. Fossil leaves (AMS dated 9190 BP) and present-day material from the same site in south west Ireland are compared with nineteenth-century herbarium material from Ireland. Techniques for obtaining reliable counts of stomata and epidermal cells from hairy leaves with sunken stomata are reported. Stomatal density and index were both found to be inversely related to CO2 concentration. The data also demonstrate the higher intra-specific variability of stomatal density over stomatal index. Analysis of the data indicates that similar investigations should be confined to single sites.

There is much evidence that herbivory is a key innovation for the tremendous success of insect. In this thesis I have investigated different aspects of host plant utilization and phenotypic plasticity using the polyphagous comma butterfly, Polygonia c-album. Even though external conditions affect a phenotypic plastic response, the outcome is often influenced by a genetic background which may differ among populations. In Paper I we suspected the genetic background to seasonal polymorphism to be X-linked. However, results from interspecific hybridization between two populations suggested that diapause response is instead inherited in a mainly autosomally additive fashion, with a possible influence of sexual antagonism on males. In Paper II we showed that female oviposition preference is not a plastic response influenced by larval experience, but has a genetic background coupled to host plant suitability. Further, there is a strong individual correlation between larval host plant acceptance and female host plant specificity (Paper III). We believe this to be a larval feed-back genetically linked to female host specificity: offspring to ‘choosy’ specialist mothers benefit by remaining on the original host while offspring to less discriminating generalist mothers should risk inspecting the surroundings, thus compensating for potential poor female choice. In the larval mid-gut, genes are differentially expressed depending on host plant diet (Paper IV). Therefore, we expected to find fitness consequences of host plant switch. However, although growth rate was affected in a few treatments, larvae were generally surprisingly good at adjusting to new diets (Paper V). To conclude, host plant choice in both female and larval life stage is connected to performance. Combined with increased understanding about the plastic response to diet intake and seasonal polymorphism we have gained further insights into the processes of local adaptations and speciation in the Lepidoptera. At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted Manuscript; Paper 5: Manuscript

Summary Reclaimed plastic containers were found to be effective as tree guards against Field Vole (Microtus agrestis) damage during the establishment of young trees in rough grassland. An experiment found that the use of the tree guards increased the average height growth of Common Sallow (Salix cinerea L.) tree setts by reducing the mortality rate due to vole damage, but did not have any effect upon the height growth of surviving trees. At Fryent Country Park over 15,000 reclaimed plastic containers have been used as tree guards. Of these, polyethylene (PE) containers were the most effective in London Clay soils, polyethylene terephthalate (PET) containers were of intermediate effectiveness, while polyvinyl choride (PVC) containers had a lifespan of only a few months which was shorter than the establishment time for the trees. Reclaimed plastic containers appeared to be as effective as commercially produced plastic tree guards.

SynopsisThe paper deals with three problem areas in the taxonomy of British willows: (1) the widespread occurrence in Perthshire and neighbouring counties of an intermediate betweenSalix myrsinifoliaSalisb. andS. phylicifoliaL., apparently of hybrid origin, though growing in an area where typicalS. phylicifoliahas yet to be found; (2) the complex taxonomy of the British Sallows, where two common aggregate species,Salix cinerea L. andS. caprea L., are each represented by two segregates; a third,S. aurita L., may also comprise more than one segregate; all three species interbreed, as do the segregates within each aggregate; (3) the disputed identity of the Crack Willow,Salix fragilis L., and its nomenclatural implications.

Temporal change in the egg-laying behaviour of Euura mucronata was studied on growing shoots of Salix cinerea. Many new shoots arise from each previous year's shoot of S. cinerea; they grow very rapidly at the beginning of the oviposition period of E. mucronata, but their growth pattern changes dramatically during the 3 weeks of oviposition. When oviposition commences, all new shoots are equally long, and E. mucronata females lay eggs on them randomly; but toward the end of oviposition, eggs are laid on the longest of the new shoots, which originate on the distal part of the previous year's shoot. By the end of oviposition, the mean proportion of ovipositor borings that had resulted in egg-laying was 65.8% on distal shoots and declined linearly to 25% on shoots arising from the base of the previous year's shoot. The proportion of attacked buds from which larvae emerged declined non-linearly from 13.8% on the distal shoot to 3.5% on the basal shoots. The position of the shoot accounted for 67% and 73% of the variance in success of egg-laying and larval development, respectively.

Final instar caterpillars of the poplar hawkmoth (Laothoe populi) are usually yellow-green when they have been feeding on Salix fragilis but white when on Populus alba. Similarly final instar caterpillars of the eyed hawkmoth (Smerinthus ocellata) vary in colour from yellow-green when fed on Salix cinerea or S. fragilis to grey-green when fed on Salix ripens or S. alba. Most caterpillars of these two moths are thus very cryptic to the human eye. It has already been shown that colour matching is brought about by young caterpillars changing colour depending on the colour of the substrate perceived by their eyes. Evidence is presented here for selective predation, probably by birds. Yellow-green poplar hawk caterpillars disappeared from P. alba more rapidly than did white caterpillars, but there was no significant difference in the survival of the two colour forms on S. fragilis. Yellow-green caterpillars survived better on S. fragilis than on P. alba, but there was no significant difference in the survival of white caterpillars on the two plants. Reasons why selective predation did not occur in all of the experiments are discussed.

Some newly created wetland areas in the Scheldt estuary are heavily contaminated by metals. They are expected to be colonised by reed (Phragmites australis) and, on a longer term, willow (Salix ssp.). Supplying litter or stimulating plant biomass production on the short term could be possible management options to restrict metal mobility or availability in the upper soil layer. The influence of litter application on the mobility and availability of metals in the top layer of a soil of a recently created floodplain along the river Scheldt (Schelde) was studied in a greenhouse experiment. Reed stem, reed leaf and willow leaf litter were dried, ground and added to the soil. The treated soil was subsequently subjected to permanently flooded and alternately flooded/drained conditions. Metal concentrations were measured in the pore water, surface water above the soil and percolates. Moreover, reed plants (P. australis), duckweed (Lemna minor) and willows (Salix cinerea) were allowed to grow on these soils. Metal concentrations in the plants, growth and chlorophyll fluorescence were measured. Decomposing litter was found to affect the metal mobility and availability. During the first weeks after litter supply, the concentrations of some metals (e.g. Cd, Cu, Ni and Zn) in the pore water markedly exceeded remediation thresholds for ground water. The metal concentrations started to decrease after some days or weeks, which might be attributed to re-adsorption to different soil phases, a decreasing presence of soluble organometallic complexes and a lowering competition with Ca2+ for sorption to the solid soil phase. However, most data point towards a role of sulphide precipitation upon sulphate reduction, which is affected by the type of litter supplied to the soil. The used willow leaf material was found to release more sulphates compared to the litter originating from reed plants. When the soils were alternately flooded, metals were exported through the percolates. Total metal export substantially increased when litter was added. Growth and metal concentrations in duckweed, reed plants and willows were affected by the supply of litter, whereas photosynthesis was less affected. The experiments should still be performed on pilot scale before developing wetland management guidelines from these results.

Total number of fruit bodies of Dermocybe uliginosa produced during the fruiting period, the rate of production and the length of the fruiting period were correlated with various micrometeorological factors. The number of fruit bodies produced per season (fruiting performance) depended mainly on the length of the fruiting period. This, in turn, depended on the fall of daily minimum air temperature immediately above soil surface (Tmin) below the critical level of 5·5 °C during the fruiting period. Short falls of Tmin ( 3 d) diminished or stopped the fruiting. The rate of production of new fruit bodies was most closely correlated with the daily mean and minimum air temperature, soil temperature and water-vapour pressure integrated for the immediately preceding 5 d. The rate of desiccation of the fruit bodies was most closely correlated with soil surface temperature and soil temperature at 0·05 m depth, again integrated for the immediately preceding 5 d. The possibility of using the total number of fruit bodies produced per fruiting period for estimating fruit body biomass production is discussed.

The onset of fruiting by Dermocybe uliginosa was studied in a willow carr surrounded by a sedge-grass marsh. The seasonal courses of various micrometeorological factors, monitored for 10 yr, were analysed as to their importance in relation to the initiation and intensity of fruiting. The regime of soil temperature at 0·05 m depth ( T s ), daily minimum temperature above the soil surface ( T min ) and water-vapour pressure ( e ) were found to control the initiation of fruiting. T s must attain, at least, 12·5 °C. A fall of T min betw I and about 5·5° for one or two days during this time was an additional stimulus to the initiation of fruiting. A decrease or increase of e for 10–20 d immediately afterwards determined whether fruit bodies were abundant or scarce.

Seasonal growth and production of individual fruit bodies were examined indirectly in permanent quadrats over 3 yr. Biomass was calculated from the ratio between average cap diameter and total fruit-body fresh or dry wt. The estimated total dry wt production in 1986 was 4·22 kg ha −1 season −1 . Seasonal changes in standing live biomass, total production and total dead biomass were established using growth curves of individual fruit bodies. The relative growth and death rates were derived for total production and total dead biomass for 3 yr. The daily average biomass increments were correlated most significantly with soil, soil surface and air temperature and water-vapour pressure.

Transect analyses emphasize the differences in tree species composition and structure of three different wooded wetland tracts in Co. Kerry, Ireland. These are variously dominated by Alnus glutinosa, Betula pubescens, Fraxinus excelsior, Quercus robur and Salix cinerea ssp. oleifolia. Stand density ranged from 16 to 54 live trees per 100 m2, tree height did not exceed 15 m, mean individual basal area ranged from 78 to 165 cm2 and the average total basal area per hectare was between 3.6 and 4.1m2. The sites were quite different in a number of the characteristics recorded. The Irish forests were smaller in stature and denser than others in both temperate zones (Continental Europe, North America, Japan) and the tropics. Crown area indices were also lower than for other areas, ranging from 1.15 to 1.79. The height: diameter relationships may reflect the state of sylvige-nesis of each stand. Death by blowdown appears to be less frequent in the younger stands than death by suppression. Gaps are therefore formed gradually, not suddenly, allowing neighbouring suppressed trees to develop into the spaces formed.

The occurrence of the mycorrhizal fungus Dermocybe uliginosa was studied in association with Salix cinerea and S. pentandra in a willow carr that was periodically flooded. In this habitat where the substrate was always moist, the initiation of fruitbody production seemed to be dependent upon a period of substrate temperature at 12.6°C or higher followed by a short episode at 5°C or less. After the appearance of fruitbodies their production seems to be directly related to relative humudity.

Salix cinerea Linnaeus, Species Plantarum 2: 1021. 1753. "Habitat in Europae nemoribus paludosis subhumidis." RCN: 7386. Lectotype (Jonsell & Jarvis in Nordic J. Bot. 14: 151. 1994): Herb. Linn. No. 1158.93 (LINN). Current name: Salix cinerea L. (Salicaceae)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part S), pp. 806-877 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 808, DOI: 10.5281/zenodo.291971

The reason why parasitoids are often unable to control insect herbivores during outbreak years has remained unclear to modern ecologists. Here I show that the blue willow beetle (Phratora vulgatissima) can escape parasitoids (Perilitus brevicollis) by reaching only a small body size during the increased competition which coincides with outbreaks. Different phases of outbreaks were simulated by allowing leaf-beetle larvae to develop at different densities on willow. The denser the herbivore populations, the smaller body sizes they attained. In the field too, herbivore body size decreased when the level of defoliation increased. The parasitoids were clearly limited by herbivore body size, exhibiting reduced survival in parallel with decreasing herbivore size, with none of them surviving in beetles from larvae reared at the highest density. The results demonstrate how bottom-up control of the herbivore becomes more important as outbreaks intensify, while top-down control gradually becomes less important and ...

Management for invasive species is expensive, costing millions of dollars every year and is sometimes unsuccessful. Current control efforts for the highly invasive willow species, Salix cinerea, are extensive, costly, and not always effective because of rapid post-removal reinfestation. An improved knowledge of the reproductive ecology of this species will help design control strategies that minimise future expansion and make current control efforts more effective. To explicitly examine the reproductive ecology of this species in its invaded range in south-eastern Australia, field observations of population structure and sex ratios, pollination experiments and germination trials were undertaken across the Ovens catchment in Victoria. Pollination-exclusion experiments strongly suggest that Salix cinerea in Australia employs two pollen-dispersal mechanisms, with insects being the dominant vector and wind playing a small but significant role (ambophilous). Seed had high initial germination rates, above 95%, but seed is very short-lived with rapid linear decline in germinability until 8 weeks, after which there was no germination at all. An improved understanding of the limited seed bank of this species and the potential it has for long distance pollination has highlighted that preventing reinfestation after control efforts should be focussed on limiting seed production and dispersal. A greater understanding of a species reproductive ecology, particularly of weed species, in their new environment can assist land managers to more effectively target their efforts for long-term eradication strategies.

Site-specific hydrological conditions affect the availability of trace metals for vegetation. In a greenhouse experiment, the effect of submersion on the metal uptake by the wetland plant species Salix cinerea and Populus nigra grown on a contaminated dredged sediment-derived soil and on an uncontaminated soil was evaluated. An upland hydrological regime for the polluted sediment caused elevated Cd concentrations in leaves and cuttings for both species. Emergence and soil oxidation after initial submersion of a polluted sediment resulted in comparable foliar Cd and Zn concentrations for S. cinerea as for the constant upland treatment. The foliar Cd and Zn concentrations were clearly higher than for submerged soils after initial upland conditions. These results point at the importance of submergence-emergence sequence for plant metal availability. The addition of foliar-based organic matter or aluminosilicates to the polluted sediment-derived soil in upland conditions did not decrease Cd and Zn uptake by S. cinerea.

The hydrological conditions on a site constitute one of the many factors that may affect the availability of potentially toxic trace metals for uptake by plants. Bioavailability of Cd, Mn and Zn in a contaminated dredged sediment-derived soil under different hydrological regimes was determined by measuring metal uptake by the wetland plant species Salix cinerea, both in field circumstances and in a greenhouse experiment. Longer submersion periods in the field caused lower Cd concentrations in leaves and bark. The wetland hydrological regime in the greenhouse experiment resulted in normal Cd and Zn concentrations in the leaves, while the upland hydrological regime resulted in elevated Cd and Zn concentrations in the leaves. Field observations and the greenhouse experiment suggest that a hydrological regime that creates or sustains a wetland is a potential management option that reduces metal bioavailability to willows. This would constitute a safe management option of metal-polluted, willow-dominated wetlands provided that wetland conditions can be maintained throughout the full growing season.

Induced increases in trichome density to grazing by herbivores have been suggested to increase plant resistance to future herbivore attack. In this paper we present results which show that plants of Salix cinerea L. respond to adult leaf beetle (Phratora vulgatissima L.) grazing by developing new leaves with an increased trichome density. The same plants are usually attacked again later in the season when the next generation of larvae hatches on the plants. The effect of the induced response was studied by comparing larval growth and feeding on newly developed leaves of plants exposed to different defoliation treatments. Larvae on plants previously exposed to adult grazing consumed less total leaf area and showed more dispersed feeding than larvae on plants protected from previous grazing. Larvae on plants exposed to mechanical defoliation responded intermediately. These results corresponded to the increased trichome density of defoliated plants. However, we found this larval response only in whole plant tests – when reared on single, excised leaves in petri dishes, larvae in all treatments behaved similarly. This discrepancy between the on-plant experiment and that in petri dishes highlights how experimental design may alter the conclusion of a study. We suggest that the induced response to adult grazing may act as a defence against subsequent larval feeding.

Nomenclature follows that of A. R. Clapham, T. G. Tutin and E. F. Warburg’s Excursion Flora of the British Isles (3rd. edn), published by Cambridge University Press in 1981, except for the following species groupings: Betula spp. (includes B. pendula, B. pubescens and their hybrid), Festuca ovina (also includes F. tenuifolia), Festuca rubra (also includes F. nigrescens), Lolium perenne (refers only to ssp. perenne; the monocarpic, and introduced, ssp. multiflorum (Lam.) Husnot is a non-persistent escapee from cultivation), Medicago sativa (excludes ssp. falcata (L.) Arcangeli which is native in East Anglia), Nasturtium officinale agg. (N. microphyllum, N. officinale and their hybrid), Poa pratensis agg. (P. angustifolia, P. pratensis sensu stricto and P. subcaerulea), Quercus agg. (Q. petraea, Q. robur and their hybrid), Rosa spp. (R. canina group, R. rubiginosa group and R. tomentosa group), Salix cinerea agg. (S. aurita L., S. caprea, S. cinerea and hybrids), Salix fragilis agg. (S. alba L., S. fragilis L. and related hybrids) and Taraxacum agg. (Section Erythrosperma, Section Obliqua, Section Palustria, Section Spectabilia and Section Taraxacum).

The aim of this work is comparing the two year performance (diameter, total height and mortality) of twenty tree and shrub species in a semi arid environment. The research also wants to supply recommendation on the agronomic cropping techniques in areas where rainfall is the main limiting factor and water use is strictly limited. Woody biomass is gaining increasing importance for energy production in Italy. During the last five years, roughly 5000 ha of Short Rotation Forestry (SRF) have been planted, mostly in northern Italy, especially using poplar clones. However, in Southern Italy, due to the poor rainfall and the lack of knowledge existing on the species to use, few groves have been established. The studied groves were set in December 2005 in a Mediterranean area where the total year rainfall is not higher than 600 mm (mostly in autumn and winter). Twenty species (Salix cinerea, Ulmus carpinifolia, Corylus avellana, Spartium junceum, Acer saccharinum, Morus alba, Saphora japonica, Eleagnus angustifolia, Fraxinus angustifolia (var oxicarpa), Sambucus nigra, Robinia pseudoacacia, Populus nigra, Albizia julibrissis, Populus alba, Salix alba, Ailanthus altissima, Alnus cordata, Ficus carica, Eucalyptus camaldulensis, Celtis australis) were planted in “collection” plots and set in singular plots on single rows (3 m X 0.5 m spacing). Six species (R. pseudoacacia, P. nigra, P. alba, S. nigra, E. camaldulensis, and A. altissima) were planted in eighteen random “experimental” split-plots, using single and twin rows (0.5 m spacing between plants). Plots had a rectangular plant spacing (3 m between singular and twin rows, 0.5 m on each row). Plant density was roughly 6670 cuttings ha-1 in “collection” plots with singular rows and 10950 cuttings ha-1 in “experimental” plots using single and twin rows. The expected harvest interval ranges from 2 to 5 years, depending on the first results. In the “collection” plots, the first results showed good performances in terms of diameter and total height of R. pseudoacacia, E. camaldulensis and E. angustifolia. The highest mortality percentage was recorded for S. nigra, P. nigra, P. alba both in “collection” and “experimental” plots. All other species showed mortality percentage lower than 20%.

In general, the participation of life strategies changes markedly with succession, this being in agreement with the theory of plant life strategies (Grime 1979, MacMahon 1980). Grime’s (1979) concept was applied in the classification of species. The features of plants which served as a basis for classification of the particular species according to their respective strategies are listed in Table 5.2. In the process of succession, especially in the initial stage, those species dominate the individuals of which exhibit properties that enable them to gain space and access to water, light and nutrient resources rapidly (strategy C). These species are classified as succession promoters and inhibitors (Table 5.2) such as, for instance, Filipendula ulmaria, Lythrum salicaria, Lysimachia vulgaris, Geum rivale, Potentilla palustris, Carex cespitosa, C. acutiformis and Salix cinerea. They remain dominant for 10–15 years, usually to the time of appearance of willows on the meadow.

The floristic composition and structure of peatland vegetation in adjoining subalpine catchments of the Bogong High Plains (north-eastern Victoria) were monitored between 1979 and 2006. Grazing by cattle had been excluded from one catchment since 1946, when it was fenced. Peatland vegetation in both catchments was partially burnt in a wildfire in 2003. Between 1979 and 1999, in the ungrazed peatland, the cover of Sphagnum cristatum Hampe and Baeckea gunniana Schauer increased and the cover of pools decreased, whereas in the grazed peatland the cover of B. gunniana and Epacris paludosa R.Br. decreased and the cover of Empodisma minus (Hook.f.) L.A.S.Johnson & D.F.Cutler increased. The cover of all recorded species decreased following a fire in 2003. Between 2004 and 2006, a significant increase in cover was detected in two of eight species measured in burnt areas. In burnt areas, the number of native species per quadrat increased in the grazed peatland and the numbers of exotic species per quadrat increased in both peatlands over that period. By 2006, the peatlands had largely recovered floristically from the 2003 fires but it is likely to be decades before the cover of S. cristatum and Richea continentis B.L.Burtt. reaches pre-fire levels. Control of several exotic species that established after the fire (especially Salix cinerea L. and Juncus spp.) may be required.

Many alluvial soils along navigable waterways are affected by disposal of dredged sediments or overbank sedimentation and contain metal concentrations that are elevated compared to baseline levels. Uptake patterns for metals and other elements by several volunteer Salix species growing on these sites were determined during a growing season in field plots and compared with the same species growing on soils with baseline contamination levels. For Cd and Zn, foliar concentrations were clearly higher on dredged sediment landfills. Uptake patterns differed significantly between species. A high uptake of Mn and low uptake of Cu, K and S in S. cinerea was attributed to wetland soil chemistry. Site effects on metal uptake were evaluated in more detail for Salix cinerea and S. alba growing on different sediment-derived sites under field conditions. Foliar Cd concentrations were higher in S. cinerea than in S. alba. This appeared to be a genetic feature not influenced by soil chemical properties, as it was observed both on clean sites and polluted sediment-derived sites. For S. cinerea, soil chemistry was reflected in foliar concentrations, while foliar Cd concentrations and bioavailability were found to be independent of the thickness of the polluted horizon. Dredged sediment landfills and freshwater tidal marshes with comparable Cd soil pollution had significantly different foliar Cd concentrations.

Summary. A new genus of coelomycetes, Pseudocytoplacosphaeria, typified by P coniicola sp. nov., is proposed, and the new species Ascochyta ulicis-caledoniensis, Phomopsis agrostidis, Phomopsis airae and Septocyta visci-britannica are described. In addition, the new combinations Phomopsis barbari (Cooke) Punith. and Septocyta visci (Bres.) Punith. & Spooner are proposed, and the following species are reported as new records for the UK: Ascochyta ligustri Sacc. & Speg., on Ligustrum, Ascochyta nigripycnidiicola Ondfej on Vicia cracca, Marssonina mali (Henn.) S. Ito on Malus sylvestris, Monochaetia cryptomeriae M. Wilson & Ford-Rob. on Taxus, Myxothyrium leptideum (Fr.) Bubik & Kabit on Vaccinium, Septoria inconspicua Berk. & M. A. Curtis on Plantago, Sphaceloma populi (Sacc.) Jenkins on Populus and Salix, and Stagonospora bellunensis (Speg.) Jorst. on Molinia. The fungi reported in this paper result largely from ongoing studies of the mycota of the Esher/Oxshott SSSI complex in Surrey, U.K Four new species, one of which represents a new genus, and five new British records from this site are presented, as well as further collections and new host records for Monochaetia cryptomeriae, previously published as British only from Scotland. Related studies on other British coelomycetes, which have identified a further undescribed species and three additional species new to Britain from other sites, are also presented here. The site at Esher/Oxshott covers an area of c. 400 ha and largely comprises acid, sandy soils (Bagshot Sands) supporting heathland as well as a wide range of other terrestrial and aquatic habitats. These include both ancient and secondary woodland composed particularly of Carpinus, Quercus and Fagus, with much Pinus and Betula, both of the latter being invasive onto the managed heathland. London Clay outcrops to the east of the area. Aquatic habitats present include ponds, streams, a spring line and bog, plus the bank of the river Mole. These areas often support Alnus glutinosa and Salix fragilis and in places sallows, mostly Salix cinerea subsp. oleifolia and S. caprea, are common. Almost the entire area is designated as a Site of Special Scientific Interest (SSSI) and parts are also designated as Local Nature Reserve. The fungi of the area have been collected and recorded for many years, early foray reports going back well over a century, e.g. Step (1895). Fairly intensive work has been undertaken during the past two decades, and to date well over 3000 species have been recorded for which voucher material of most is held in K or IMI. It is the holotype locality for at least 35 species to date, including 27 hyphomycetes, although no coelomycetes have been previously described from the area. There is as yet no comprehensive account of