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<p> Increasingly large and severe fires across the western United States are creating difficult challenges for land managers. Despite the wide usage of current post-fire hillslope treatments, their effectiveness varies. Some research even shows negative impacts, such as the spread of invasive species. </p><p> The use of select post-fire colonizing mosses or &ldquo;fire moss&rdquo; is a promising post-fire stabilization treatment and longer-term restoration tool that has never been investigated for use in high severity burned environments. Fire mosses possess traits that make them ideal candidates for restoration purposes such as: universal distribution, desiccation tolerance, high water holding capacity, and soil aggregation ability. Fire mosses also are apparently succeeded by vascular plants. Harnessing the restoration power of fire mosses, finding ways to bring them to additional critical post-fire sites, and hastening their arrival on scene could provide a valuable service not currently being utilized. Our research addresses the basic questions surrounding the effectiveness of fire mosses in post-fire stabilization and restoration since there is no know prior work in this field. Field experiments were conducted to determine if fire moss could be grown on post-fire sites. Results show that inoculation increased moss growth by nine times and moss cover was an order of magnitude greater on high severity burned plots than either moderate or unburned plots. Subsequently, greenhouse experiments were conducted to find optimal growth conditions under which an inoculum supply source could be grown for field application. Results show that greatest moss growth occurred under five and seven day per week watering schedules, with fire moss Bryum argenteum constituting a majority of overall moss growth in the less frequent watering schedules suggesting that this moss would be the best candidate for use in marginal fire moss habitat (lower elevation, drier, and more exposed sites). Additionally, mosses Funaria hygrometrica and Ceratodon purpureus grew more prolifically in sample units with ash, while the opposite was true for Bryum argenteum, suggesting that future research should be conducted on the underlying mechanism. Overall, fire moss showed promise as a plausible restoration material, leading us toward future research given its potential to avoid problems caused by other hillslope treatments.</p>

The island of Oronsay in the Inner Hebrides contains five Late Mesolithic shell middens. This research uses ecological investigations on limpets (Patella spp.), periwinkles (Littorina littorea L.) and dogwhelks (Nucella lapillus L.) from the present Oronsay coast to aid an interpretation of the shellfish collection strategies of the Mesolithic hunter-gatherer populations, and to establish. the relative importance of the three shellfish species in their diet. Section A is devoted to ecological examinations of contemporary limpets, periwinkles and dogwhelks, and in Section B this information is applied to the midden shellfish. In chapter an examination is made of previous research into selected aspects of the ecology of the three species, which forms a necessary basis for the present research. In each species an examination is made into studies concerning population dynamics (reproduction and mortality), the distribution of the animals over the shore, growth, and the physiological ecology of body and shell development. Chapter 2 examines seasonal meat weight changes (ie body weights) in animals from an area of the present Oronsay coast at different tidal levels over a full year. For chapter 3 further fieldwork was carried out around the Oronsay coastline to examine the difference in population structure of the three species in varying coastal environments, and at different tidal levels. Attention was paid to variations in size in each of the species, and their relative proportions between sample sites. An examination was also made of shape distribution of limpets at different tidal levels. Chapter 4 makes comparisons between present Oronsay coastal environments and those of the Mesolithic, with relation to coastal morphology and exposure, and sea temperature, to assess the validity of using contemporary data to interpret activities on Mesolithic Oronsay. Section B begins with a brief synopsis of the main approaches that have previously been adopted in midden studies. Chapter 6 then uses information gained in chapter 3 to explain the size distribution of each species in the middens, the shape distribution of the midden limpets, and the relative proportions of the three species, in terms of the collection strategies of the midden dwellers. Interactions xix between the human predators and the shellfish populations will be reflected in the size-frequency structure of the midden shellfish from the base to the top of the middens. From sample columns in each midden an assessment is made of the intensity and periodicity of exploitation, and of the relative importance of each of the three shellfish species. Chapter 7 uses data from chapter 2 to reconstruct the relative proportions of meat weight provided by each shellfish species in the middens. Account is taken both of shellfish size, tidal position, and the varying amounts of meat which may have been obtained at different seasons. Seasonal changes in body weight are demonstrated in limpets, periwinkles and dogwhelks from the present Oronsay coast, which are related to their reproductive cycles and feeding intensities. When this information is applied to the midden shells, at each possible collection season limpets are shown to provide around 90% of the shellfish meat weight. On the modern coast the relative proportions of the three species vary greatly from different shore environments, yet in the middens there is a much greater uniformity in the relative numbers of the three species. There are no major changes in species composition or size upward through the middens, and it is argued that this indicates a fairly low intensity, regular exploitation.

My study confirms that there are phenotypic plastic traits in blue mussels (Mytilus edulis) inresponse to predatory pressure from shore crabs (Carcinus maenas) and sea stars (Asteriasrubens) and a combination of them. Blue mussels can sense predators by olfactory cues fromthe predators themselves, or by alarm cues from attacked conspecifics, and then developinducible defences. In this experimental study, blue mussels were exposed to either nopredator (control) or to enclosed predators in terms of two shore crabs, two sea stars or thecombination of one shore crab and one sea star, over a period of six weeks. According to previous studies a good defence against predation from shore crabs should be athicker and also a more circular mussel shell, and a good defence against sea stars should be astrong posterior adductor muscle. All three predatory treatments resulted in mussel individuals with significantly heavier shells.When exposed to sea stars, individuals grew less lengthwise and showed a significantly lowerend volume, as well as a significantly heavier posterior adductor muscle. These mussels alsoshowed a tendency to survive sea star predation better in the predation test. Thus, induciblephenotypic defences against predation by sea star predation, were clearly demonstrated. Theexposure to shore crabs resulted in a significantly higher height of the mussels, whencontrolling for mussel length. The mussels exposed to shore crabs also showed end volumessimilar to control mussels, whereas an exposure to a combination of a crab and a sea starresulted in intermediate end volumes. This supports a phenotypic plasticity in traits related topredator threat. Individuals in all three predatory treatments were harder attached by morebyssus threads at the end of the experiment. Control mussels and those exposed to a singlecrab and sea star were repeatedly found to be more aggregated (i.e. fewer solitary mussels)over the course of the experiment, whereas the mussels presumably exposed to more olfactorycues from two shore crabs or two sea stars were more often found solitary and attached bybyssus threads. This study demonstrated inducible defences in how blue mussel allocate their resources todifferent dimensions of growth, shell weight, adductor muscle weight, as well as aggregationand byssus attachment, depending on predatory threat.

1) Fluoride concentrations were investigated in 6 lichens and a moss growing on stone walls around the aluminium smelter at Invergordon. 2) These plants were able to accumulate elevated amounts of fluoride from the atmosphere. The highest level of fluoride occurred near the smelter and in the direction of prevailing winds. 3) Lichen surveys on three different substrates (fence-posts, trees and stone walls) revealed that lichens colonizing all these habitats were badly damaged in polluted areas. 4) A lichen desert was observed on the fence posts closer to the smelter. a5) Some species of lichens were absent from these substrates in the vicinity of smelter and did not appear until some distance away from the emission source. 6) These observations suggested that crustose lichens, due to their presence closer to the smelter, were more resistant to fluoride pollution than either foliose or fruticose lichens. 7) Transplant studies showed that lichens absorbed large amounts of fluoride from the polluted atmosphere around the aluminium smelter. a8) Fluoride concentration in the transplanted lichens increased with increasing time of exposure. 9) Four lichens transplanted in the same locality accumulated varying amounts of fluoride in their thalli. 10) The transplanted lichens were visually damaged and discoloured in zones of high pollution. 11) This discolouration was concurrent with decline in net photosynthesis and chlorophyll content of the thalli. 12) The reduction of net photosynthesis was also related to an increasing amount of fluoride in the lichen thalli. 13) The declining rate of net photosynthesis in a 'sensitive' species (i.e. H. physodes) was greater than in the 'resistant' species (P. saxatilis). 14) Laboratory studies revealed that lichens were able to accumulate large amounts of fluoride from hydrogen fluoride gas and sodium fluoride solutions. 15) Various lichens absorbed different quantities of fluoride from the same pollution levels. 16) The net photosynthetic rates of lichens decreased with increasing concentrations of hydrogen fluoride gas in fumigation chambers or fluoride ions in sodium fluoride solutions. 17) The effects of fluoride applied as hydrogen fluoride gas were more acute and rapid than those from sodium fluoride solutions. 18) Various lichens showed different physiological responses to the same external concentrations of fluoride (whether gaseous or in solutions). 19) The internal concentrations at which damage occurred were similar for each species, whether fluoride was applied as hydrogen fluoride gas or sodium fluoride solution. 20) The order of species sensitivity remains the same in whatever the form of fluoride applied and whether it is applied in the field or under laboratory conditions. 21) Field transplantation suggested that H. physodes exposed to the rain water was less affected by fluoride pollution than samples which were protected from rain. 22) The "unexposed" samples accumulated more fluoride in their thalli than the "exposed" lichens and consequently showed greater morphological and physiological abnormalities. 23) The chlorophyll content and net photosynthesis of both "exposed" and "unexposed" lichen samples decreased after 12 weeks transplantation. The lichens which were "exposed" showed a 50% reduction in net photosynthesis, whereas "unexposed" samples protected from rain water showed no positive net photosynthesis and contained considerably less chlorophyll. 24) Ultrastructural studies of H. physodes samples, fumigated with graded series of hydrogen fluoride gas, revealed disruption of chloroplasts in algal cells (i.e. Trobouxia). 25) The disruption of chloroplast i.e. formation of vesicles and their size increased with increasing the fluoride accumulation in the lichen thalli. No major change in the fungal cells was observed.

The ecology of wood mice (Apodemus sylvaticus) found in fields of oilseed rape (Brassica napus oleifera) around Newburgh, Aberdeenshire was studied from October 1990 to December 1992. The animals' population dynamics were studied by live trapping with mark and recapture, their home range sizes and habitat utilisation were determined by radio-tracking, their diets were analysed by microscopic examination of stomach contents, and their preferences for oilseed rape were assessed by feeding trials. Population densities of wood mice in oilseed rape fields, at 1.6 to 12.5 per ha, were generally lower than those of woodland mice, but were comparable to those of wood mice on arable land found in other studies. The seasonal fluctuations in wood mouse densities in oilseed rape fields differed slightly from those described for woodland mice, with peak densities found in spring or summer. Both agricultural practices and the type of adjacent habitats affected the mean densities and seasonal fluctuations in densities of wood mice in oilseed rape fields. The mean home range size of radio-tracked wood mice in this study (0.34-0.88 ha) was larger than those reported for woodland mice, but smaller than those reported for wood mice on sand dunes. Although there were no statistically significant differences between seasons, the mice tended to make less use of oilseed rape fields during the early stage of the crop, but increased their use of oilseed rape fields as the oilseed rape plants grew older. The diet of wood mice caught in oilseed rape fields was similar to those of wood mice in agricultural fields in other studies, in that seed formed the major part of their diet, while vegetative parts of plants and animal food were taken seasonally as supplementary foods. Oilseed rape was eaten by wood mice in a noticable amount only in April, when flowering buds and flowers were always eaten, and in June, when young seeds of oilseed rape were frequently eaten. Only young seeds of oilseed rape, not old ones, were found to be as preferred by wood mice as young seed of barley or wheat.

Some members of two tropical genera of the Euphorbiaceae, Macaranga and Mallotus were studied to determine how and why they are successful pioneers. Aspects of reproductive biology were studied in a total of eight species of Macaranga and two of Mallotus, although detailed observations were limited to a single species of each genus. The majority of work was carried out. in the Pasoh Forest Reserve and Ulu Gombak Forest Reserve in W. Malaysia. 2. All species of Macaranga and Mallotus studied produced flowers at least once each year. Both Mallotus macrostachyus and Mallotus paniculatus bloomed regularly each-July, but there was a wide variation amongst Macaranga species since M.heyneii flowered continuously while the majority of other species flowered at about eight month intervals. Observations on M.hypoleuca demonstrated an alternation between the vegetative and reproductive phases in mature trees. 3. Most Macaranga species produced large numbers of flowers with male trees carrying about 35x more than females. Flowering populations alsio usually contained more male trees. Macaranga flowers are generally small, green and inconspicuous, arising from the leaf axils. Mallotus however produces inflorescences terminally, and although the flowers are small, they are more noticable by virtue of their bright yellow colour. 4. M.hypoleuca produces seed through cross-pollination and most probably also by agamospermy, thereby maintaining genetic variability while allowing the replication of well adapted genotypes through facultative apomixis. Mallotus macrostachyus sets seed only following cross-pollination, Therefore these two pioneers, occurring in the same habitat, exhibit two different kinds of breeding system. 5. Male trees of both genera were visited by generalised pollinators e.g. Trigonids, but these were not found on female flowers, Chironomids did visit flowers of both sexes and may have transferred pollen by ''mistake". Thrips were present in both male and female flowers and therefore may be potential pollinators. 6. High fruit production was a feature of most species, and Macaranga fruits especially attracted many birds and squirrels. Bulbuls especially carried seed away from the tree thereby probably effecting successful dissemination. Many seeds fell directly beneath the tree, and most appeared to germinate immediately in this position. 7. A small proportion of Macaranga seeds appeared capable of remaining viable for up to one year, but most fresh seeds seem to geminate very soon after fruit fall. 8. Although no significant seed bank was found in forest soil, indirect evidence such as the rapid mass germination of Macaranga seeds after forest clearance, followed by no further germination, indicated that it was highly likely that dormant seed was present in the soil. 9. There was a very low Macaranga seed rain inside the forest, and this . source seemed unlikely to account for the mass seed germination following forest clearance or formation of large gaps. 10.Macaranga seeds germinate successfully both in disturbed and undisturbed soil, indicating the operation of a number of stimuli for germination, light and temperature variations probably being most important. 11. The germination of Macaranga seed under greenhouse conditions was enhanced by red light and inhibited by green light. Germination experiments in the forest showed that there was significant sprouting Macaranga seeds in gaps of all sizes, while seeds placed beneath the primary forest canopy failed to germinate. 12. Despite the presence of a dynamic gap phase in Pasoh F.R., Macaranga species are not well represented except in large natural gaps. 13. Macaranga species are the dominant pioneer species in most cleared areas inside the forest, and in most man-made clearances. As forest disturbance continues in Malaysia, Macaranga species are increasingly becoming a major feature of regrowth vegetation. 14. Various topics for further study have been recommended, Macaranga and Mallotus species being ideal subjects, since they occur widely in S. E. Asia.

Birch readily colonizes heather moorland in the absence of regular burning, and successional changes in the dominance of various plant species take place beneath the developing woodland. Birch (unlike Calluna vulgaris and many conifers) has long been thought to have an ameliorating effect on soils. Changes such as this in association with other environmental changes accompanying the development of birch woodland can have complex and often interactive effects on the species involved in a succession of this sort. It is not known to what degree the changes in species dominance beneath developing birch can be attributed to soil changes or to other factors such as changing light levels, leaf litter, or grazing animals, for example. This thesis examines some of the species changes taking place beneath birch stands of different ages which have colonized heather moorland in north-east Scotland and attempts to elucidate some of the mechanisms controlling these species changes. (1) Examination of seed inputs revealed that this factor restricts the colonization of some, but not all, later successional species. (2) Germination of most species was unaffected by age of birch stand, but early growth of all species improved with increasing age of birch stand. (3) Results of experiments altering light intensity, nutrient availability and simulated grazing gave information on the relative importance of these factors in controlling the species changes beneath the birch stands studied. (4) The predictive ability of a Markov model in the simulation of succession under birch was shown to be limited; the use of this model did generate some interesting hypotheses about the nature of some of the processes of change operating in this successional system.