Estimates of long-term forest site productivity are required to inform multiple forest management objectives including growth and yield assessments, silvicultural planning, and biomass/carbon projections. Estimates traditionally have been quantified in the form of site index by measuring the average height-age relationships of dominant and codominant trees or using regional site index equations. Site index implementation requires that trees are free from suppression and that height growth results from the integration of the biological determinants of growth. While useful in even-aged stands, early age height growth suppression is common in uneven-aged forest structures making existing site indices difficult to assess. Additionally, the individual biological determinants of growth are not identified and do not provide a basis for site index to be mapped across the landscape or predicted under alternative climate scenarios. This research aims to characterize the major physiographic and climatic determinants of growth. We obtained site index estimates for 203 ponderosa pine, 343 Douglas-fir, 232 lodgepole pine and 99 western larch trees throughout the state of Montana using regional equations (Milner 1992). Terrain descriptors (slope, aspect and elevation), climate normals (min/max temperatures, vapor pressure deficit), and climatic water balance (actual evapotranspiration and deficit) were derived for each site index tree at various resolutions (list range of resolutions ). Regression analysis was performed using a hierarchy of terrain, climate and mixed models. Slope, aspect, and elevation were able to explain approximately half the variation in site index for ponderosa pine, lodgepole pine and western larch. Geographically localizing the model increased the variance explained by the terrain models for all species except western larch. A simple climatic water balance interaction model (AET x DEF) was unable to explain much of the variation in site index. However, when climatic water balance was added to the terrain model the variance explained increased for all species. A biophysical model utilizing only water balance and climate variables explained more of the variation in site index than terrain based models for all species. Implications of spatial accuracy of the climatic data products and fine scale variation in tree data are discussed and recommendations for future research are provided.

<p> Soil respiration is a major flux of carbon to the atmosphere in terrestrial ecosystems. If belowground carbon cycling processes are disrupted, as by N deposition in northern hardwood forests, there could be feedbacks to atmospheric CO₂. Despite its importance in the global carbon budget, soil respiration is not widely studied across different levels of nutrient availability in soils. In this study, we measured soil respiration across northern hardwood forest sites of differing fertility and age in the White Mountains of New Hampshire. </p><p> Across the range of soil nutrient availability, soil respiration and belowground carbon allocation were lower in sites with relatively low nutrient availability compared with sites categorized as medium or high fertility. Soil respiration and belowground carbon allocation did not differ significantly with forest age. </p><p> Summer soil respiration rate was not correlated to soil P and Ca availability, but was low in soils with high N availability. This result suggests that greater N availability in soils may contribute to less belowground carbon allocation in northern hardwood forests. </p><p> To further study single and synergistic nutrient effects on soil or microbial respiration, nitrogen and phosphorus were applied in treatments of: N-only, P-only, N+P, and control. There were no significant N or P fertilization effects on soil or microbial respiration after two years of fertilization treatment. </p><p> To study microbial respiration alone, five stands (4 plots in each stand) were selected in which living roots were severed by digging trenches. Although total soil respiration did not change after fertilization, the contribution of microbial respiration to soil respiration increased significantly in N+P plots compared to N-only and control plots with trenches. Microbial respiration in laboratory incubations also suggested that there were no discernible changes in Oe and Oa horizons after fertilization. </p><p> Data from this study suggest that nutrient availability, particularly N, can affect soil respiration. The two-year study period was not long enough to detect fertilization effects on soil and microbial respiration, hence long-term tracking of the fertilization treatments in this study will be necessary to determine if belowground carbon flux changes in response to increased N and P availability in soils.</p>

No description available.

The research scope of this thesis focused on traditional forest management practices in eastern Psiloritis Mountain in Crete, employing oral history, archival information and GIS. The main focus was over the end of the 19th century till present. The useful and productive forest of the past, extensively exploited by local populations, is often considered nowadays as unproductive and thus neglected by modern society. Historical and social incidences influenced the behaviour of local population towards natural resources and their interaction with their natural environment has changed over time. Therefore, different traditional management practices were applied locally in the past and recorded in this thesis. A unique forest landscape was evolved based on a complex system of interactions among the trees with animals and the human population that were dependent on the forest. The use of GIS helped unveil a wealth of information further elucidating archival material and explain better different geographical phenomena. Several management practices of the past contributed for the creation of a rich biodiversity and cultural elements helped shape the forest landscape of Psiloritis. The importance of this traditional management was highlighted with regard to the conservation of the forest today. In this way the thesis shows that forest history can help modern forestry to establish a more effective management of the forests for the benefit both of the environment and the society.

This thesis investigates the influence of niche specialisation on floristic composition and species distributions of the family Dipterocarpaceae along topographic gradients at two contrasting lowland Mixed Dipterocarp Forest sites in Brunei Darussalam: Andulau (overlying nutrient-poor sandy soils) and Belalong (overlying nutrient-rich clay soils). Dipterocarp tree density, species richness and diversity were higher at Andulau than Belalong, and were also higher on ridges than in slopes and valleys. Randomisation tests detected significant dipterocarp species associations with site and tomography. Dipterocarp floristic composition was strongly correlated with various habitat variables at Belalong, even after accounting for distance between samples. In contrast, fewer habitat variables were correlated with dipterocarp floristic composition at Andulau, implying weaker habitat effects in this more topographically homogeneous site. In a field-based transplant experiment, <i>Dryobalanops aromatica </i>and <i>Dryobalanops rappa </i>seedlings consistently showed higher growth rates and survival in gaps than in understorey plots. Higher survival and leaf production of <i>D. aromatica </i>seedlings at Andulau than Belalong provide evidence of a habitat preference. Growth and survival of <i>D. rappa</i> seedlings were similar at the two sites, but <i>D. rappa</i> seedlings grew significantly faster in height than <i>D. aromatica </i>seedlings on slopes at both sites. In conclusion, local and landscape scale variations in edaphic and environmental resources influence dipterocarp species distributions and floristic composition, as well as dipterocarp seedling growth and survival. Thus, niche specialisation is an important mechanism in the maintenance of species coexistence at Andulau and Belalong.

<p> Over the past decade, the government of Laos has granted extensive tracts of land to plantation, mining, and hydropower investors across the country, constituting five percent of the national territory. Such projects have transformed rural livelihoods and environments, particularly via the dispossession of the lands, fields, and forests that Lao peasants rely upon for daily subsistence and cash income. While large-scale land acquisitions, or land grabs, across the Global South have been countered by social protest and movements in many countries, organized and vocal social mobilization is largely absent in Laos due to authoritarian state repression of dissident activity perceived to be anti-government. Lao peasants, however, have increasingly crafted politically creative methods of resistance that have enabled some communities and households to maintain access to land that had been allocated to investors. In this dissertation, I examine how effective resistance materializes within the Lao political landscape, by resisting with the state, shaping how industrial tree plantations are governed and their geographies of agrarian-environmental transformation. </p><p> The overarching argument of the dissertation is that in authoritarian contexts, like Laos, peasants are able to maintain access to land by taking advantage of political relations among state, corporate, and community actors that provide politically feasible means of refusal. Peasants find ways to resist that tread a middle path, that do not challenge state hegemonic power nor engage in under-the-radar acts of everyday resistance. Instead, they exploit and refashion established lines and relations of power among communities, state agencies, and plantation managers. They resist within the bounds of state power. Political relations between resource companies and the state vary, affecting how state sovereignty is mobilized to dispossess peasants of their land. Communities targeted by companies with weak relations with the state are afforded greater opportunities to contest such projects as they are not developed with the heavy coercion afforded to companies with better state relations. Communities that have powerful political connections with the state are also in a better position to resist. They are able to more effectively lodge their claims with the state when they have the political links to do so, particularly ethnic and kinship ties developed during the Second Indochina War. Communities more effectively resist the acquisition of lands that are afforded greater value by the state, particularly lowland paddy rice fields and state conservation areas. Finally, internal community relations, particularly democratic decision-making and solidarity, shape how effectively they mobilize against unjust land dispossession. </p><p> These arguments draw upon 20 months of in-country, ethnographic fieldwork during which I studied the operations of two plantation companies in 10 villages of Phin and Xepon districts, eastern Savannakhet province, southern Laos. One company is a state-owned Vietnamese rubber enterprise while the other is a private Chinese paper and pulp company planting eucalyptus and acacia trees. The bulk of the data comes from semi-structured one-on-one and focus group interviews with government officials at all administrative levels, civil society organizations, plantation company managers, village leaders, village households, and village women. The study is also deeply informed by participant observation &ndash; particularly with Lao government officials, civil society organizations, and rural communities &ndash; and by participatory mapping exercises and collected investment project documents. </p><p> The dissertation makes novel contributions to the discipline of geography. First, I demonstrate the importance of contested political ethnography, a methodological approach through which immersion in uncomfortable and oppositional political situations provides insights that would otherwise go unnoticed. Second, I contribute to understandings of how nature-society transformations occur in under-studied, authoritarian political contexts where neoliberal reforms are integrated with a heavy-handed role of the state in the economy. Third, I theorize how resistance can materialize and be effective in such contexts, despite its heavy repression. Fourth, I contribute to understandings of how dispossession actually occurs in practice and is governed by varying political relationships, leading to geographically variegated agrarian-environmental transformations.</p>

<p> Yellow-cedar is a long-lived conifer of the North Pacific Coastal Temperate Rainforest region that is thought to be undergoing a continued natural range expansion in southeast Alaska. Yellow-cedar is locally rare in northeastern portions of the Alexander Archipelago, and the fairly homogenous climate and forest conditions across the region suggest that yellow-cedar&rsquo;s rarity could be due to its local migrational history rather than constraints on its growth. Yellow-cedar trees in northern range edge locations appear to be healthy, with few dead trees; additionally, yellow-cedar tend to be younger than co-dominant mountain and western hemlock trees, indicating recent establishment in existing forests.</p><p> To explore yellow-cedar&rsquo;s migration in the region, and determine if the range is expanding into unoccupied habitat, I located 11 leading edge yellow-cedar populations near Juneau, Alaska. I used the geographic context of these populations to determine the topographic, climatic, and disturbance factors associated with range edge population establishment. I used those same landscape variables to model suitable habitat for the species at the range edge. Based on habitat modeling, yellow-cedar is currently only occupying 0.8 percent of its potential landscape niche in the Juneau study area. Tree ages indicate that populations are relatively young for the species, indicating recent migration, and that most populations established during the Little Ice Age climate period (1100 &ndash; 1850).</p><p> To determine if yellow-cedar is continuing to colonize unoccupied habitat in the region, I located 29 plots at the edges of yellow-cedar stands to measure regeneration and expansion into existing forest communities. Despite abundant suitable habitat, yellow-cedar stand expansion appears stagnant in recent decades. On average, seedlings only dispersed 4.65 m beyond stand boundaries and few seedlings reached mature heights both inside and outside of existing yellow-cedar stands. Mature, 100 &ndash; 200-year-old trees were often observed abruptly at stand boundaries, indicating that most stand boundaries have not moved in the past ~150 years. When observed, seedlings were most common in high light understory plant communities and moderately wet portions of the soil drainage gradient, consistent with the species&rsquo; autecology in the region.</p><p> Despite an overall lack of regeneration via seed, yellow-cedar is reproducing via asexual layering in high densities across stands. Layering may be one strategy this species employs to slowly infill habitat and/or persist on the landscape until conditions are more favorable for sexual reproduction. This study leads to a picture of yellow-cedar migration as punctuated, and relatively slow, in southeast Alaska. Yellow-cedar&rsquo;s migration history and currently limited spread at the northeastern range edge should be considered when planning for the conservation and management of this high value tree under future climate scenarios.</p>

Abstract This dissertation explored sustainable forest management from multiple perspectives: a literature-based investigation to define management practices that sustain ecological, economic, and social forest resources over time; a field-based research project to identify management practice differences between Forest Stewardship Council (FSC) certified, Sustainable Forestry Initiative (SFI) certified, and uncertified properties in Maine; and a field-based research project to identify stand structural differences between FSC certified and uncertified properties in Vermont. Based on an extensive literature review, we developed an iterative decision-making framework of goal-setting/implementation/ monitoring/review that could assist forest owners in choosing management practices to sustain ecological, economic, and/or social capital over multiple time frames. Our unique contribution is the identification of six concrete management concepts at the implementation phase: (1) BMPs/RIL, (2) biodiversity conservation, (3) community forestry, (4) forest protection, (5) sustained forest product yield, and (6) triad forestry. Forest owners can implement practices under one or more of these concepts to achieve their sustainability goals. We illustrate a hypothetical application of our framework with a case study of an FSC certified managed natural forest in the lowland tropical region of Costa Rica. In the white pine forests of south-central Maine, we compared three FSC, SFI, and uncertified private properties against local scale Montreal criteria using triangulation of evidence from management documents, staff interviews, and field inspections. Certified properties were associated with improved internal management systems and improved practices for biodiversity conservation. However, our data suggest that certification does not necessarily involve fulfillment of all Montreal criteria, such as adherence to sustained timber yield, consideration of multiple social issues, or ecological monitoring at multiple temporal and spatial scales. In northern hardwood stands in central Vermont, we compared three FSC certified and three uncertified that were analogous in terms harvesting date, silvicultural treatment type, forest type, and general location. The uncertified sites were randomly selected to remove bias. We conducted stand structural analysis of both live trees and standing and downed coarse woody debris, and also developed 10-year growth projections using FVS/NE-TWIGS. Our data suggest that FSC certified stands had similar timber economic value, similar live tree structure, and similar tree carbon storage, but significantly greater residual coarse woody debris than comparable uncertified harvested stands.

<p> Though land conversion and flow alteration have heavily impacted the Sacramento River riparian ecosystem, restoration opportunities still exist in the hydrogeomorphically active Middle Reach. This study of riparian forest succession focused on six dominant riparian tree species to explore relative establishment timing and the potential impacts of altered flow regimes. We utilized tree inventory data and increment cores collected from riparian forest stands to establish a temporal chronosequence of floodplain surfaces and associated tree ages and colonization timing. Tree age calculations incorporated raw ring counts and sampling error simulations. Results were then used to construct species-specific, diameterage models and predict age distributions for all inventoried trees. Cottonwood&rsquo;s colonization window was longer than expected (up to 95 years after floodplain creation), whereas box elder and walnuts established on floodplains &lt;50 years old. This study lays the groundwork for future research into the health and development of the Middle Reach riparian forest.</p>

No description available.