A goal of efforts to restore altered ecosystems is to reestablish natural disturbance processes, such as fire, that govern ecosystem structure and function. In ecosystems where structure has changed in response to human activities, however, ecosystem drivers may function differently and their reestablishment could yield unexpected or undesired consequences. Lehmann lovegrass, Eragrostis lehmanniana, a perennial bunchgrass from Africa, was introduced to grasslands in the southwestern United States in the 1930s and has since increased in distribution and dominance. Reintroducing fire has been proposed as a mechanism by which to restore semi-desert grasslands by reducing the dominance of nonnative plants, despite the altered plant community.To assess the effect of nonnative grass on animals, between 2000 and 2004 we sampled 54 plots across a gradient of invasion by nonnative grass and quantified variation in presence, abundance, and richness of insects and small mammals. For small mammals, we used a framework we developed to estimate abundance when data are sparse. The number of insect orders, families, and morphospecies, as well as overall abundance decreased as nonnative grass increased. Many insect families that decreased in abundance as nonnative grass increased were comprised of herbivorous species, suggesting that increases in nonnative grass may have reduced abundance and quality of plant foods. Abundance of several species of murid rodents increased and several species of heteromyid rodents decreased as nonnative grass increased, indicating clear changes in habitat for these species of small mammals.To assess the interactive effects of prescribed fire on small mammals in these altered ecosystems, we performed a randomized experiment where we applied prescribed fire on 36 of 54 plots. The effects of fire on many small mammal populations and the composition of the small mammal community varied along the invasion gradient, suggesting that fire functions differently inareas dominated by nonnative plants relative to those dominated by native plants. Invasion by this nonnative grass has clearly shifted the composition of faunal communities in semi-desert grasslands and has altered ecosystem processes, therefore reestablishing fire is not likely to be an omnibus solution for restoration.

Although boreal forest management typically results in an increased frequency of even-aged forest stands in managed landscapes, fire history research suggests that much of the natural forest mosaic is composed of stands characterised by multiple cohorts of trees. To aid in the development of multicohort management, I investigated stand structural characteristics and small mammal communities as a function of their tree cohort structures. I also tested key alternatives: stand age, productivity, and tree species composition, as correlates of structural variation and small mammal communities. Results reveal that in mixedwood and black spruce forests, three-dimensional structure of boreal forests is strongly correlated with small mammal community structure, and indicate that tree diameter distribution is a succinct descriptor of such structural variation, performing better than alternative stand characteristics. This represents a new approach to characterising habitat supply as a function of within-stand heterogeneity, contrasting with existing approaches that focus on among-stand characteristics.

Although boreal forest management typically results in an increased frequency of even-aged forest stands in managed landscapes, fire history research suggests that much of the natural forest mosaic is composed of stands characterised by multiple cohorts of trees. To aid in the development of multicohort management, I investigated stand structural characteristics and small mammal communities as a function of their tree cohort structures. I also tested key alternatives: stand age, productivity, and tree species composition, as correlates of structural variation and small mammal communities. Results reveal that in mixedwood and black spruce forests, three-dimensional structure of boreal forests is strongly correlated with small mammal community structure, and indicate that tree diameter distribution is a succinct descriptor of such structural variation, performing better than alternative stand characteristics. This represents a new approach to characterising habitat supply as a function of within-stand heterogeneity, contrasting with existing approaches that focus on among-stand characteristics.

The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park. Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid. The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence. Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire. Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota. Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance. Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.

Η αποκάλυψη της παρουσίας ενός νέου είδους ποντικού, του Mus cypriacus Cucchi et al., 2006, ενδημικού της Κύπρου, απέδειξε πόσο ελλιπείς είναι οι γνώσεις μας ως προς την πανίδα των μικροθηλαστικών της Κύπρου. Στην Κύπρο θεωρούνταν γνωστά τα είδη Mus musculus domesticus και Mus macedonicus. Τελικά απεδείχθη ότι το μέχρι τότε γνωστό ως Mus macedonicus ήταν το ενδημικό Mus cypriacus. Προκειμένου να μελετηθούν τα μικροθηλαστικά του γένους Mus στην Κύπρο, στα πλαίσια της παρούσας μελέτης πραγματοποιήθηκαν δειγματοληψίες για πέντε δειγματοληπτικές περιόδους (άνοιξη 2008 - άνοιξη 2009), σε δύο περιοχές της Κύπρου, στην πεδινή περιοχή της επαρχίας Αμμοχώστου (περιοχή Λίμνης και Νοσοκομείου Παραλιμνίου), καθώς και στην ορεινή περιοχή του Όρους Τροόδους (περιοχή Κάτω Πλατρών). Στόχος της παρούσας εργασίας ήταν να ελεγχθεί η ύπαρξη των δύο ειδών στις δύο περιοχές οι οποίες χαρακτηρίζονται από διαφορετικούς βιοτόπους και να ελεγχθεί κατά πόσον ισχύουν οι οικολογικές τους προτιμήσεις. Μέχρι τώρα, θεωρείται ότι το Mus cypriacus είναι αγροδίαιτο είδος, ο βιότοπός του περιλαμβάνει εγκαταλειμμένους αμπελώνες, λιβάδια και θαμνώδεις εκτάσεις και εξαπλώνεται στην περιοχή του Όρους Τρόοδος σε υψόμετρο 300 - 900 m, ενώ δεν εξαπλώνεται σε περιοχές με ισχυρή ανθρωπογενή πίεση, όπως καλλιέργειες στη Μεσαορία (στο κεντρικό τμήμα του νησιού), ανθρώπινες κατοικίες και φάρμες, όπου εξαπλώνεται κυρίως το Mus musculus domesticus. Σε επόμενο στάδιο, επειδή δεν έχουν γίνει πολλές μελέτες ακόμη για το Mus cypriacus και ο ταξινομικός προσδιορισμός του είδους των ζώων που συλλέχθηκαν δεν ήταν εφικτός με βάση τα γνωστά διακριτικά εξωτερικά μορφολογικά χαρακτηριστικά των ειδών, αλλά και επειδή ο ταξινομικός προσδιορισμός δεν μπορούσε να γίνει με βεβαιότητα, λόγω της επικαλυπτόμενης μορφολογικής ποικιλότητας των ειδών, έγινε προσδιορισμός με τη χρήση μοριακών μεθόδων. Συγκεκριμένα, πραγματοποιήθηκε ανάλυση αλληλουχίας στο τμήμα της D-loop περιοχής ελέγχου του μιτοχονδριακού DNA το οποίο απομονώθηκε από κύτταρα του ήπατος. Περαιτέρω, για να γίνει μορφομετρική σύγκριση των πληθυσμών, εφαρμόστηκε γεωμετρική μορφομετρική ανάλυση σε κρανιακούς (ραχιαία και κοιλιακή κρανιακή επιφάνεια) και ανάλυση περιγράμματος σε οδοντικούς χαρακτήρες (κάτοψη περιγράμματος πρώτου άνω γομφίου, M1). Τα ευρήματα της παρούσας μελέτης διευρύνουν την περιοχή εξάπλωσης του Mus cypriacus, τόσο ως προς τον οικολογικό χαρακτήρα των βιοτόπων του (συλλέχθηκε όχι μόνο σε φυσικούς οικοτόπους, αλλά και σε οικοτόπους με έντονη ανθρωπογενή επίδραση) όσο και ως προς την οριζόντια (εξαπλώνεται μέχρι το νοτιοανατολικότερο άκρο της Κύπρου, το Παραλίμνι, μια περιοχή για την οποία δεν υπήρχαν στοιχεία έως τώρα) και κατακόρυφη εξάπλωσή του (εξαπλώνεται σε υψόμετρο από 44 m (Παραλίμνι, κοιλάδα Μεσαορίας) μέχρι 1015 m (Κάτω Πλάτρες, Όρος Τρόοδος). Η ανάλυση της αλληλουχίας ενός τμήματος της D-loop περιοχής του mtDNA αποκάλυψε ότι η ενδοπληθυσμιακή ποικιλότητα των κυπριακών πληθυσμών του είδους Mus musculus domesticus είναι πολύ μεγαλύτερη σε σχέση με τις αντίστοιχες τιμές ελληνικών πληθυσμών του ίδιου είδους. Σε αρκετές περιπτώσεις, και για τα δύο είδη του γένους Mus, η ενδοπληθυσμιακή ποικιλότητα ήταν μεγαλύτερη της διαπληθυσμιακής. Το χαμηλό ποσοστό διαπληθυσμιακής ποικιλότητας υποδηλώνει ότι οι μελετηθέντες πληθυσμοί διαφέρουν πολύ λίγο σε γενετικό επίπεδο, αφού φαίνεται να υπάρχει γενετική ροή μέσω ενεργητικής μετανάστευσης ή παθητικής μεταφοράς ατόμων. Η νουκλεοτιδική και απλοτυπική ποικιλότητα έλαβαν τιμές από τις μεγαλύτερες που έχουν αναφερθεί σε παρόμοιες μελέτες. Η ύπαρξη προγονικών πολυμορφισμών σε συνδυασμό με τη δράση της γενετικής εκτροπής ευθύνονται για τα υψηλά επίπεδα πολυμορφισμού που εμφανίζουν οι κυπριακοί πληθυσμοί των δύο ειδών Mus, συγκρινόμενοι με άλλους πληθυσμούς της υπόλοιπης περιοχής εξάπλωσής τους. Η εφαρμογή της γεωμετρικής μορφομετρικής ανάλυσης και της ανάλυσης περιγράμματος που αφορούν αντίστοιχα στα κρανιακά και οδοντικά χαρακτηριστικά των ειδών της παρούσας εργασίας, αποκαλύπτει τη σαφή διάκριση των ειδών Mus cypriacus και Mus musculus domesticus, τα οποία διαχωρίζονται πλήρως ως προς τους χαρακτήρες που χρησιμοποιήθηκαν ως μορφομετρικοί δείκτες (ραχιαία και κοιλιακή κρανιακή επιφάνεια και περίγραμμα πρώτου άνω γομφίου, Μ1). / The discovery of a new endemic mouse in the island of Cyprus in 2006, Mus cypriacus Cucchi et al., 2006, proved how little we know about the Cyprus small mammal fauna. In order to study the two mouse species of the genus Mus occurring in Cyprus, two geographically distant and ecologically different areas were investigated. The first of these areas lies on Mt. Troodos, in abandoned fields near the forest edge, and the second is situated in the Famagusta area, in farmland with sparse shrub vegetation. In the context of this study, we conducted samplings for five sampling periods, (spring 2008 - spring 2009). The aim of this study was to determine the existence or not, of the two species in both areas and to check their ecological preferences. So far, it is known that Mus cypriacus seems to be absent from areas with strong anthropogenic pressure such as the overexploited agricultural fields, human dwellings and farms in the Mesaoria plain (which includes our second study area) where the House Mouse, Mus musculus domesticus, is almost exclusively dominant. As far as the altitudinal distribution range of Mus cypriacus is concerned, it has been reported mainly on Troodos mountain and the adjacent regions, on altitudes between 300-900 m. Since the taxonomic distinction between the two Mus species in our material was not always safe, on the basis of traditional morphological characters, we conducted mtDNA analyses. The mitochondrial DNA (mtDNA) control region was sequenced from 44 mice collected from both studied areas. In addition, analysis of shape variation of cranial characters (venral and dorsal view) and outline analysis of dental characters (outline of first upper molar, M1) was conducted using Geometric Morphometrics and Elliptic Fourier Analysis (EFA). Our results suggest that Mus cypriacus inhabits a wider range of habitats than it was known, as it was collected not only in more natural areas but also in areas with strong anthropogenic pressure, such as farmlands, abandoned fields and other rural areas. Moreover, we revealed that this species has a more expanded altitudinal and horizontal geographical range, given that it was found from 44 m (Paralimni, Mesaoria plain) to 1015 m (Kato Platres, Mt Troodos). The sequence analysis of a part of the D-loop region of mtDNA region revealed that the values of intra-genetic distance calculated for Mus musculus domesticus populations are greater than the ones calculated for Greek populations of the species. In many cases, the intra-genetic distances were greater than the inter-genetic distances. The low percentage of inter-population genetic diversity observed indicates that the populations examined differ slightly on genetic basis since there is substantial genetic flow among them, possibly due to genetic drift and active migration or passive transportation. The values of nucleotide and haplotide diversity were among the greatest ones reported from similar studies. The presence of ancestral polymorphisms in combination with the genetic drift are accountable for the high levels of polymorphism of the two Mus species in Cyprus. According to our results, Geometric Morphometrics and Elliptic Fourier Analysis (EFA) for both cranial and dental characters resulted in a clear discrimination of the populations. These two characters were found to be suitable for discrimination for both species inhabiting Cyprus.

Esta dissertação fez parte do projeto temático “Conservação da Biodiversidade em Paisagens Fragmentadas no Planalto Atlântico de São Paulo”, que teve como objetivo geral estudar os efeitos da fragmentação da Mata Atlântica sobre diversas comunidades e processos ecológicos na região de Caucaia do Alto, SP. A dissertação está dividida em três capítulos centrais e duas abordagens principais. A primeira delas utilizou dados coletados por mim e outros pesquisadores com o objetivo de testar o uso de uma metodologia de captura de pequenos mamíferos relativamente nova e pouco utilizada nos trópicos, comparando a sua eficiência com a da metodologia mais tradicional de coleta de dados sobre estes animais (capítulo 2). Estudos recentes demonstram que a matriz, conjunto de ambientes alterados que circundam os remanescentes em paisagens fragmentadas, considerada inicialmente inóspita e homogênea, funciona como um mosaico de unidades com diferentes permeabilidades ao deslocamento ou à ocorrência das espécies. Dentro deste contexto, a segunda abordagem desta dissertação corresponde à descrição e comparação do uso, pelos pequenos mamíferos, dos ambientes alterados que envolvem os remanescentes de floresta (capítulo 3) e à utilização deste tipo de informação para o estudo da influência da estrutura da paisagem sobre a distribuição de espécies (capítulo 4). No capítulo 2, para avaliar a eficiência e a congruência entre tipos de armadilhas, amostramos a comunidade de pequenos mamíferos de forma padronizada usando armadilhas Sherman e de queda em 26 sítios, 20 localizados em fragmentos florestais e seis em floresta contínua. Os resultados sugerem que armadilhas de queda, quando constituídas por baldes grandes e profundos e utilizadas nas épocas chuvosas e quentes, não só complementam a diversidade encontrada com o uso de armadilhas tradicionais, como podem triplicar a riqueza por sítio de amostragem, incluindo espécies raras, de hábitos semi-fossoriais e espécies escansoriais/arborícolas geralmente não atraídas pela isca das armadilhas tradicionais. Apesar das diferenças de eficiência, os resultados sugerem que os dados obtidos com os dois tipos de armadilhas são congruentes e que variações de diversidade e abundância entre sítios são semelhantes entre os métodos. As armadilhas de queda também parecem ser essenciais em estudos demográficos, já que capturam indivíduos em uma amplitude maior de peso, incluindo os jovens, raramente capturados nas armadilhas tradicionais. No capítulo 3, para avaliar a qualidade da matriz para os pequenos mamíferos na região de Caucaia do Alto, utilizamos os dados de amostragens padronizadas realizadas em 23 sítios, sete localizados em remanescentes florestais (floresta contínua e fragmentos) e 16 distribuídos nos quatro tipos predominantes de habitats da matriz (vegetação nativa em estádios iniciais de regeneração, plantações de eucalipto, áreas de agricultura e áreas rurais com construções). Houve forte segregação na comunidade de pequenos mamíferos entre a vegetação nativa e demais habitats, indicando a capacidade extremamente reduzida das espécies florestais de ocupar habitats antropogênicos. A vegetação nativa em estádios iniciais apresentou uma razoável permeabilidade para as espécies florestais, sugerindo o potencial da regeneração natural para a restauração de paisagens fragmentadas de Mata Atlântica. Os habitats antropogênicos foram dominados por espécies generalistas, exóticas ou típicas de biomas abertos, sugerindo que paisagens muito alteradas possam ser dominadas por estas espécies, com conseqüências para a regeneração das florestas e para a saúde humana. No capítulo 4, a partir dos resultados da distribuição das espécies de pequenos mamíferos nos habitats do mosaico, informações sobre a qualidade destes habitats foram utilizadas na avaliação da influência da estrutura da paisagem sobre a ocorrência das espécies em 20 fragmentos florestais, com o objetivo de comparar o poder explanatório de métricas que consideram ou não a qualidade da matriz e investigar a importância da escala espacial. Os resultados indicam que a influência da estrutura da paisagem é maior para as espécies que não ocorrem na matriz, ou entre as que ocorrem, para aquelas que não ocupam todos os ambientes da paisagem. Em geral, os modelos com as métricas que consideram a qualidade da matriz apresentaram maior poder explanatório sobre a distribuição das espécies nos fragmentos. Dentre as métricas que consideram a qualidade da matriz, aquelas que incorporam a distância entre as diferentes manchas de habitat mostraram vantagens em relação às que consideram apenas a área das manchas, pois apresentaram maior poder explanatório sobre a ocorrência de um maior número de espécies e menor variação do poder explanatório em relação a mudanças na escala espacial considerada. Esta ultima característica é importante dada a falta de uniformidade observada na resposta das espécies à variação da escala espacial e a escassez de informações que embasem a escolha de escalas espaciais adequadas para espécies tropicais. / This dissertation was developed as part of the thematic project “Biodiversity Conservation in Fragmented Landscapes at the Atlantic Plateau of São Paulo”, which aimed at studying the effects of the fragmentation of the Atlantic forest on several communities and ecological processes in Caucaia do Alto, SP. This dissertation is divided in two main approaches that comprise three chapters. In the first approach, I used data collected by myself and by other researchers with the objective of testing the use of a relatively new and little explored methodology to capture small mammals in the tropics, comparing its efficiency to the methodology that is tradicionally ised to collect data about these animals (chapter 2). Recent studies have shown that the matrix of altered habitats surrounding remnants in fragmented landscapes, considered initially as inhospitable and homogeneous, act as a mosaic of units presenting different degrees of permeability to the movement or to the occurrence of species. Within this context, the second approach of this dissertation concerns the description and comparison of use of the altered habitats surrounding forest remnants by small mammals (chapter 3) and to the use of this type of information for the study of the influence of landscape structure on species distribution (chapter 4). In chapter 2, aiming at the evaluation of the efficiency and congruence of different types of traps, we sampled the small mammal community using a standardized procedure, with Sherman and pitfall traps in 26 study sites, 20 located in forest fragments and six in the continuous forest. Results suggest that large and deep enough pitfall traps used during wet and warm periods, not only complement the diversity found using traditional traps, but also leads to an considerable increase in the number of species found at each study site, including rare species, semi-fossorial species and scansorial/arboreal species that are usually not attracted to the bait used in traditional traps. Despite differences in efficiency, results suggest that data gathered with the two types of traps are congruent and that the variation in diversity and abundance among study sites is similar between the two methods. Pitfall traps also seem to be essential in demographic studies because they are able to capture individuals within a larger range of weights, including young individuals, which are rarely captured using traditional traps. In the chapter 3, to evaluate matrix quality for the small mammals in Caucaia do Alto, we used data from standardized sampling in 23 study sites, seven of which were located in forest remnants (continuous and fragmented forest) and 16 were distributed in the four main types of matrix habitats (native vegetation in initial stages of regeneration, eucalyptus plantation, areas of agriculture and rural areas with buildings). There was a strong segregation in the small mammal community between native vegetation and the other habitats, indicating the extremely low capacity of forest species to occupy anthropogenic habitats. Native vegetation in initial stages presented a reasonable permeability to forest species, suggesting the potential of natural regeneration to restore fragmented Atlantic forest landscapes. Anthropogenic habitats were dominated by generalist species, exotic species or species that are typical from open biomes, suggesting that highly altered landscapes may be dominated by these species, with consequences to forest regeneration and to human health. In chapter 4, using the results of the distribution of the small mammal species in the habitats of the mosaic, information on the quality of these habitats was applied in the evaluation of the influence of landscape structure on the occurrence of species in 20 forest fragments, aiming to compare the explanatory power of metrics that consider or not matrix quality and to investigate the importance of spatial scale. Results indicate that the influence of landscape structure is stronger for species that do not occur in the matrix, or for species that do not occur in all habitats in the mosaic. In general, the models using metrics that consider matrix quality presented higher explanatory power on the distribution of species. Among the metrics that consider matrix quality, those that incorporate distance among different habitat patches presented advantages in relation to those that consider only patch area, because they presented a higher explanatory power to the occurrence of a larger number of species and lower variation in the explanatory power in relation to changes in spatial scale. The later characteristic is important given the lack of uniformity observed in species response to variations in spatial scale, and the scarcity of information that could support the choice of adequate spatial scales for tropical species.

Anthropogenic change in the Great Plains of North America within the past two centuries has facilitated extensive woody encroachment by eastern redcedar (Juniperus virginiana, hereafter redcedar). Conversion of grassland to redcedar woodland occurs rapidly as a result of the interaction between changing disturbance and land use patterns. In addition, redcedar encroachment causes compositional shifts in grassland floral and faunal assemblages, and may alter abiotic factors such that grassland restoration efforts are limited. The objectives of this study were to: 1) track vegetation and faunal assemblages in grasslands along a gradient of redcedar encroachment, 2) assess the capacity for experimental tree removal to promote re-colonization of grasslands by associated flora and fauna, and 3) examine the influence of scale on spatial relationships between small-mammal abundance and redcedar cover. During the first phase of my study, I examined herbaceous vegetation, woody vegetation, and small-mammal assemblages at grassland sites along a redcedar encroachment gradient in north-central Oklahoma. I noted hump-shaped trends in the capture rate, species diversity, and species evenness of small mammals along the redcedar encroachment gradient. In addition, higher levels of encroachment were associated with compositional shifts from grassland- to woodland-associated small mammals. Characteristics of the small-mammal assemblage along the gradient corresponded to increases in redcedar cover and the frequency of episodic management events within the past two decades. Experimental redcedar removal during the second phase of my study generally increased vegetation and faunal diversity in 2 years following treatment, and treatment sites having the highest pre-treatment levels of redcedar cover exhibited the greatest responses to tree removal. The results of my study suggested that within the time frame I examined, redcedar encroachment had altered the biotic characteristics of this system, but did not facilitate abiotic shifts capable of constraining rapid grassland recovery. Tree removal also appeared to modulate the effects of consecutive drought and flood years on small-mammal diversity during post-treatment. During the third phase of my study, I examined the strength of association between differences in percent redcedar cover and spatial abundance patterns of 4 common small-mammal species. I examined small-mammal abundance at three relatively small spatial scales (38, 154, and 616 m2) to determine how redcedar-mammal associations were stronger with increases in spatial scale. In addition, I determined whether the influence of spatial scale on redcedar-mammal associations varied along a gradient of redcedar encroachment. The strength of redcedar-mammal associations increased with spatial scale, but was strongest at sites having the lowest levels of encroachment. These results corresponded to variation in the spatial distribution of redcedar cover and compositional differences in the small-mammal species assemblage along the encroachment gradient. Studies examining the effects of woody encroachment will extend our understanding of successional processes and ensure that appropriate management is implemented in the conservation of these imperiled grassland ecosystems.

No description available.

Through the last 60 million years (Ma) there were well-documented climate and habitat changes across North America. Continental and regional scale studies on ungulate (hooved mammals) tooth crown heights in relation to climate and habitat changes have documented an increase in tooth height as environments became more arid to combat a highly abrasive diet of fibrous plants and grit. Based on the relationships between crown height and climate, several studies have used taxon free methods to estimate past precipitation from fossil ungulates. Small mammals have also been shown to adapt to changing habitats, with specializations for life in open habitats appearing millions of years earlier than larger mammals. Utilizing taxon free methods, this study compared the crown heights of rodents and lagomorphs (rabbits and pika) from across North America to climate variables, including both temperature and precipitation. Studying small mammals allows examination of local changes to climate and can be informative of what is to be expected in regional communities if modern warming trends continue. Using ArcMap, modern climate data and mammal faunal lists for 100 random points were compiled and generated across North America. Crown heights of species were categorized and mean crown height for the community was calculated for each site. Linear regressions were used to examine the relationship between crown height and climate variables. Using ArcMap and ordinary kriging, maps were generated of predicted climate for all of North America and compared to known climate data. In general, the North-South gradient of temperature and the Northwest to Southeast gradient of precipitation was captured in predicted maps showing agreement with known climate maps. Regressions were also used to predict climate for 72 well-known fossil sites from the late Eocene (~37 Ma) to Pleistocene (~1.9 Ma) of North America, generating estimates of temperature and precipitation for many sites with no prior climate estimates. Results show strong correlation between rodent and lagomorph crown heights and temperature and precipitation variables. Temperature variables were more strongly correlated to tooth crown heights than precipitation. Overall, a decrease in precipitation and temperature was found across North America from 37 Ma to the present, consistent with prior paleoclimate records from other regional and global proxies. Application to detailed regional records from the Mid Miocene Climatic Optimum (around 15 Ma, during the early Barstovian land mammal age), which was a pronounced period of warming comparable to the warming we see today, showed regional variation in responses to warming. Tooth crown height increased in California and Nebraska before Oregon, showing climate did not change uniformly across North America similarly to what would be expected in modern warming. Using the method proposed in this study, past and future regional climate trends, as well as biotic responses to those changing climate trends can be better understood.

Proper habitat management is essential for the survival and reproduction of species, especially those listed under state or federal laws as endangered, threatened or of special concern, and those with small local populations. Land managers use a combination of mechanical cutting and prescribed burning to manage and restore degraded scrub habitat in east central Florida. This approach improves habitat for the endangered Florida scrub-jay (Aphelocoma coerulescens), but little is known about its effects on other taxa, especially the threatened southeastern beach mouse (Peromyscus polionotus niveiventris). This single species approach may not be beneficial to other taxa, and mechanical cutting and prescribed burning may have detrimental effects on P. p. niveiventris. To evaluate the effects of land management techniques on P. p. niveiventris, I live trapped populations at Cape Canaveral Air Force Station near Titusville, Florida during 2004-2005. I evaluated the relative abundance and related demographic parameters of small mammal populations trapped in compartments under different land management treatments, and investigated the relationship between Florida scrub-jay breeding groups using these compartments and abundance of southeastern beach mice. My results suggest that P. p. niveiventris responded positively to prescribed burning, while the cotton mouse (P. gossypinus) responded positively to the mechanical cutting. Reproduction and body mass of southeastern beach mice were similar across land management compartments. Abundance of Florida scrub-jay breeding groups and southeastern beach mice were positively correlated suggesting that both listed species benefited from the same land management activities. A mosaic of burned and cut patches should be maintained to support small mammal diversity. In addition, adaptive management should be used at CCAFS to understand how small mammals, particularly the southeastern beach mouse, respond to land management activities.