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No description available.

No description available.

To evaluate the compression wood response in eastern white pine (Pinus strobus L.) following a severe ice storm in 1994, 47 trees were felled in 2007 and cross-sectional samples were collected at 0.5 (±0.2) m stem height. The disks were sanded and digitally scanned, and the cross-sectional area (mm2) of compression wood within each tree-ring was quantified using image analysis software. Topographic data (slope, aspect, and elevation) were also recorded for each P. strobus tree, along with a modified competition index. Wood anatomical features were also quantified in the three years before and after the storm along a tree diameter gradient. Although tree age was relatively constant in this stand, tree size was influenced by topographic position; larger trees grew in the valley while smaller trees were found growing in thin soils at the mid-slope position. When the cohort was about 25 years old, ice deposition caused a heterogeneous compression wood response which was highly related to tree size. In the thirteen years following the ice storm, the 6 – 9 cm (2007) diameter class formed significantly more compression wood area than any other, followed by the 10 – 13 cm (2007) diameter class. The tree diameter range that formed the most post-storm compression wood was 4 – 8 cm at the time of the storm, suggesting that this diameter range was most affected by 8.5 cm of ice loading in P. strobus. Trees > 18 cm in 1994 did not form any compression wood after the storm, but many experienced a growth release to fill canopy gaps. Topographic variables did not influence compression wood formation directly, but only one plot was sampled so these results are tenuous. However, topography did influence tree size which was the most important predictor in compression wood. There was no relationship between compression wood area and competition index. Due to compression wood formation after the ice storm, cell wall thickness and cell circularity were significantly higher in the 1994 tree-ring than in other rings examined (1991 – 1993, 1995, and 1996). Tracheid and lumen diameters were significantly smaller in compression wood cells (30.5 and 19.5 μm, respectively) than in normal wood (36.8 and 28.4 μm, respectively); opposite wood cells were intermediate in size (32.4 and 24.4 μm, respectively). Due to small tracheid size, compression wood contained significantly more cells mm⁻¹ (33) than normal wood (27), but no significant differences in cell wall area. Therefore, cumulative cell wall area occupied 47% of the cross-section in compression wood tissue on average, compared to 31% in normal wood. Dispersing tree weight across a greater surface area may help compression wood to prop up a bent tree, but reduced lumen area may also impact hydraulic conductivity in the stem. / Master of Science

A forest site quality index (FSQI) based on topographic parameters of aspect, slope inclination and slope position was used to investigate soil moisture and plant water stress relationships on the southeast face of Potts mountain in Craig County, Virginia. Topographical effects on available water are especially pronounced during low late season rainfall levels encountered in the Ridge and Valley physiographic province of Virginia. The soil moisture trends and plant water potentials demonstrated that for all forest site quality index values representing the topographically derived moisture gradient, available soil moisture and plant stress levels probably seriously decrease or inhibit tree growth from the middle of July to the end of the growing season. The Forest Site Quality Index (FSQI) delineated the soil moisture gradient within the study area most successfully in the more xeric areas, supporting its use for predicting relative site quality on those sites where soil moisture has been demonstrated as being the limiting factor of tree growth. The FSQI is a rapid and easy measure based on topographic parameters for evaluating relative site quality but is restricted in use to areas where rainfall is critical to plant growth during the growing season. / M.S.

Forests are more than a stand of trees in the landscape. They represent a complex, functional system of interacting and often interdependent biological, physical and chemical components (Kimmins 1997). In the past, complex interactions were increasingly recognized over time as food webs, abiotic processes and biotic feedbacks since then defined as the forest ecosystem. Trees grow in a world of multitrophic interactions (van der Putten et al. 2001). One component of this functional system is represented in several aspects by spiders and insects, as they contribute considerably to the biodiversity and ecosystem functioning in forest habitats (Watt et al. 1997). There is knowledge on the community composition of several forests of different stand type or tree species composition referring to soil dwelling arthropods. Moreover, studies often highlight the orientation of single arthropod species on abiotic factors or the composition of species assemblages in case studies; these represent ecologically well described groups that can be used as indicators of habitat quality (Pearce and Venier 2006; Cardoso et al. 2004). Evidence on the scale of interactions between the species and their environment are rare. This applies particularly to examples based on fine spatial and temporal scales.

A long-term forest monitoring program was initiated at Mammoth Cave National Park (MCNP). The objectives of this project were to establish baseline data on the representative forest community types at MCNP based on dominant tree species. Permanent monitoring plots were established in different forest community types throughout the park. A total of 32 permanent plots were established for a combined sample area of 11.4 hectares. All stems larger than 5 cm dbh were measured and mapped within each permanent plot. Data on saplings were also collected. Distributions and abundances were determined for all species in permanent plots and combined for community type summaries. Stand tables were generated for four stem diameter size categories for each permanent plot. Stand analyses included calculation of values for species in four size categories.The results describe the forests of MCNP in various stages of succession. There is a trend toward increasing dominance of shade tolerant species in several of the community types. Species composition is in transition from the dry site, shade intolerant species in the canopy to shade tolerant species in the understory. Corpus f lorida, Acer saccharum, Fagus grandifolia, and Acer rubrum are prominent species in the understory and sapling layers. Early successional species continue to dominate heavily or recently disturbed locations on karst and dry upland sites. Juniperus virginiana is the dominant species in three of the seven community types sampled. The Hemlock and Beech-Maple Communities, Community Types II and VIII, appear to be maintaining their present species compositions and community structures. These are successionally "mature" forests, and include some of the most ecologically important areas of the park. However, Betula alleghaniensis is not reproducing in the Hemlock ravines community type, the only sites where this species occurs. Ailanthus altissima, an invasive exotic tree, was found in several of the areas sampled. / Department of Biology

This thesis investigates past structure and dynamics of native Caledonian pine woodland, representing part of the western fringes of the northern European boreal woodlands. The biogeographical extent and Holocene history of the Scottish pine woods are well studied, yet questions remain at finer scales. This thesis is concerned with two factors over the recent Holocene oceanic period; (i) the long-term ecology within the woods; the spatio-temporal dynamics, the canopy structure, and community composition and continuity; and (ii) the former extent of the woods, especially the temporal pattern of the inferred easterly contraction in woodland over recent history. The importance of these factors - to ecologists, challenged with understanding the theories of equilibrium and non-equilibrium processes in long-lived woodland communities - and to conservation managers - challenged, by policy directives, with implementing the restoration and expansion of native woodlands - is discussed. Equally the identification and quantification of ecological detail over ecologically relevant temporal and spatial scales is an important challenge for palaeoecology. The thesis therefore applies fine spatial resolution pollen analyses over a network of sites, within, and at the western edge of, the extant woodland zone in east Glen Affric. Correlation between these individual site histories develops a detailed view of the grain and extent of woodland within the landscape, previously missing from western pine woods. Careful attention is paid to the interpretive potential and limitations of fine resolution palaeoecology; especially with regard (i) to techniques that can identify and spatially quantify stand-scale structure and community composition via reference to modern analogues; and (ii) to defining chronologies and elucidating rates and patterns of temporal change. The opportunities and limitations of the technique are explored and discussed, to ensure an understanding of the rigour and potential of the palaeoecological contribution to ecological research and to provide an evidence base for conservation. The application of 210Pb dating using the CRS and CIC models is explored. The CRS model is confirmed as suitable for peat deposits, but its use may mask fluctuations in peat sedimentation rate, which may be illustrated by the CIC model. The value of multiple 14C assays for each core and a need for a new approach to chronologies for application to fine-scale palaeecological studies is discussed. The relevant source area around the small basins in this semi-open pinewood is tentatively confirmed at 20 m from the pollen source. Tentative pollen productivity estimates for five key taxa in this ecosystem are presented. The temporal stability of native woodland in Glen Affric is confirmed to the eastern part of the extant woodland zone; but challenged to the west, where the open and semi-open landscape has a long history. Woodland diversity decreased over the last c. 200 years, and past woodland also shows a greater ground flora diversity. The western extent of the Caledonian woodland in this landscape may have changed little in the last c. 4000 years. Fluctuations, some clearly cyclical, in heath, and in woodland, communities are identified in the pollen record. The former may be aligned to changes in grazing regime or climatic shifts; and the latter to autochthonous shifts important in the maintenance of suitable edaphic conditions for the continuity of woodland. Former woodland is confirmed as likely to have been open in structure and mixed in tree species composition. The results presented here suggest that some caution should be applied to use of the term Caledonian, or native ‘pine’ forest: ‘Caledonian forest’ may better reflect the heterogeneity of past forests, particularly the importance, and persistence, of birch. The implications for conservation management and restoration are discussed. It may be difficult to establish a sustainable woodland to the west of the extant stands, and any pine woodland here may need to be mixed with stands of broadleaved trees to maintain or restore soil structure and ecological function. The landscape to the west may have been open for several thousands of years, and consideration of this is required when managing for the future to prevent loss of biodiversity.

<p>Forest canopies are a critical component of forest ecosystems as they influence many important functions. Specifically, the structure of forest canopies is a driver of the magnitude and rate of these functions. Therefore, being able to accurately measure canopy structure is crucial to ensure ecological models and forest management plans are as robust and efficient as possible. However, canopies are complex and dynamic entities and thus their structure can be challenging to accurately measure. Here we study the feasibility of using lidar to measure forest canopy structure across large spatial extents by investigating the compatibility of aerial and terrestrial lidar systems. Building on known structure-function relationships measured with terrestrial lidar, we establish grounds for scaling these relationships to the aerial scale. This would enable accurate measures of canopy structural complexity to be acquired at landscape and regional scales without the time and labor requirements of terrestrial data collection. Our results illustrate the potential for measures of canopy height, vegetation area, horizontal cover, and canopy roughness to be upscaled. Furthermore, we highlight the benefit of utilizing multivariate measures of canopy structure, and the capacity of lidar to identify forest structural types. Moving forward, lidar is a tool to be utilized in tandem with other technologies to best understand the spatial and temporal dynamics of forests and the influence of physical ecosystem structure. </p>

A exploração de produtos não madeireiro em florestas nativas tem sido alternativa na composição da renda de comunidades locais. Dentre as diversas espécies exploradas da Mata Atlântica, a biriba - Eschweilera ovata (Cambess.) Miers - vem sendo intensamente utilizada para a confecção do berimbau. Disponibilizar informações que auxiliem em apontar diretrizes para adequadas formas de conservação genética e manejo desta espécie é de fundamental importância, tanto do ponto de vista ecológico como econômico e social. Com este objetivo, realizou-se o estudo do sistema reprodutivo e da estrutura ge nética de E. ovata, através da técnica de eletroforese de isoenzimas, em três áreas de ocorrência natural de populações da espécie sob diferentes graus de antropização, sendo uma explorada e outras duas sem exploração, localizadas próximas à cidade de Salvador - BA. Os resultados do sistema de reprodução, obtidos para duas populações, mostram que a espécie reproduz-se predominantemente por cruzamento, tendo $ t m variado de 98,5% a 99,9%, valor este superior à média apresentada pelas espécies arbóreas tropicais. Uma certa taxa de cruzamentos endogâmicos foi evidenciada nas populações estudadas, sendo praticamente 100% da endogamia gerada nas progênies resultado de cruzamento entre parentes na população natural, e 76,8% na população explorada, sendo o restante atribuído a autofecundação. O valor estimado para o coeficiente de coancestralidade dentro de progênies ( $qF ) variou de 0,191 a 0,211. As estimativas das correlações de autofecundação ( s rˆ ), foram relativamente baixas em ambas as populações e não diferentes estatisticamente entre si, (variando de 0,100 a 0,107). O número provável de árvores doadoras de polén foi extremamente baixo, tendo em média, dois indivíduos por árvore matriz. O tamanho efetivo de variância (Ne(v)) médio das populações foi de 2,13, sendo necessário assim, para reter o tamanho efetivo de 50, a coletas de cerca de 23 árvores nestas populações. O tamanho efetivo populacional foi próximo ao número de indivíduos amostrados. A divergência genética entre as populações de adultos ( $ q pA ), foi de apenas 2,5%,indicando que a maior parte da diversidade genética encontra-se distribuída dentro das populações (97,5%). A divergência entre populações, estimada com base nas progênies ( $ q pP ) foi ainda menor, de 1,4% (0,1 a 3,5 O número médio de alelos por locos foi de 2,14 nos adultos e de 2,41 nas progênies. A porcentagem de locos polimórficos nas árvores adultas foi de 85,4% e nas progênies de 81,8%. A heterozigosidade esperada segundo as expectativas do Equilíbrio de Hardy-Weinberg (EHW) foram altas e variaram de 0,354 a 0,431, e a heterozigosidade observada variou de 0,332 a 0,371, sendo, tanto na progênies como nos adultos das populações, menor do que a heterozigosidade esperada, indicando que há mais homozigotos nas populações que o esperado pelas proporções do EHW. A análise de autocorrelação espacial das árvores de E. ovata dentro da populações estudadas mostrou haver estruturação, sendo que quanto mais próximos os indivíduos maior é probabilidade deles serem parentes. Os resultados obtidos possibilitaram realizar inferências a respeito da conservação e manejo da espécie. / The exploitation of non-timber resources from tropical forest has been an alternative income to local human communities. Among the tree species which are exploited in the Atlantic forest, the “biriba" – Eschweilera ovata (Cambess.) Miers – has been used to manufacture the arc of “berimbau". The genetic conservation and the sustainable management of E. ovata populations are necessary to guarantee the longterm exploitation of this resource in an ecological, as well economic and social point of view. Adequate management strategies can be planned by getting information about the population genetic structure and mating system of the species. The aim of this study was to evaluate the mating system and the population genetic structure of E. ovata, using the allozyme electrophoresis technique. Three populations under different levels of human action in an area of natural occurrence of E. ovata near Salvador, Bahia state, were chosen. The results of the evaluation of the mating system of E. ovata, obtained for two population, indicate that the species reproduces itself through outcrossing. The outcrossing rate ($ t m ) varied from 98.5% to 99.9%. These values are higher than that average estimates observed in tropical tree species. Inbred crosses were observed in the progenies. Almost 100% of the inbreeding observed in the non-disturbed population and 76.8% in the exploited population was due to crossing among related individuals. Selffertilization was also observed. The estimated value of the coefficient of the coancestrality among the progenies ( $qF ) varied from 0.191 to 0.211. The estimates of self- fertilization correlation ( s rˆ ) were low and statistically similar and non significant in both populations (the values varied from 0.100 to 0.107). The expected number of pollen donors was extremely low, having an average of two pollen donors by mother-tree. The average effective number of variance (Ne(v)) was 2.13. With this estimate was possible to conclude that it is necessary to collect about 23 adult trees in these populations to keep an effective size of 50. The effective population size was similar to the number of individuals sampled. The genetic divergence among the adult populations ( $ q pA ) was 2.5%, showing the genetic diversity is mainly distributed within populations (97.5%). The genetic divergence among the populations obtained from the progenies ( $ q pP ) was also lower, 1.4% (0.1 to 3.5%). The average number of alleles by loci was 2.14 in the adult populations and 2.41 in the progenies. The percentage of polymorphic loci was 85.4% in the adults and 81.8% in the progenies. The expected heterozigosity varied form 0.354 to 0.431 and the observed heterozigosity varied from 0.332 to 0.371. The values of observed heterozigosity were inferior to the expected heterozigosity, indicating that there are more homozygous individuals than expected by the Hardy Weinberg Equilibrium. The spatial autocorrelation analysis of E. ovata shows that there is intrapopulational genetic structure in the studied populations of adult individuals. Closer individuals show a higher probability of being genetic related. The results obtained in this study are helpful to infer about the genetic conservation and the management of the species.