Forest disturbances and the spatial patterns they create affect ecosystem processes through their influence on forest vegetation from individual trees to landscapes. In the boreal and mixed-wood forests of eastern Canada the main agents of disturbance are logging, fire, and defoliation by the spruce budworm (SBW, Choristoneura fumiferana). These disturbances are similar in that they remove forest biomass and influence forest succession but also distinct in that logging creates patterns that are different than those created by natural disturbances. All disturbances are indirectly linked to each other through their mutual effects on forest spatial structure and succession. Through such feedbacks, spatial disturbance legacies can facilitate or constrain further disturbances, including forest management. Surprisingly, the long term spatial consequences of interactions among multiple natural and anthropogenic disturbances remain largely unexplored. This thesis investigates how, and at what spatial scale, legacies in forest composition and age structure influence natural disturbance dynamics, and how natural disturbances constrain forest management. I address four specific questions: (i) For how long do spatial legacies of different forest management strategies persist on the landscape? (ii) How do interactions among logging, fire, SBW, and succession affect timber availability and long term forest patterns in age and composition? (iii) How do these patterns differ from those created by each disturbance individually? And, (iv) How can management be used to reduce the extent and severity of fires and SBW defoliation through the manipulation of forest structure? The key scientific innovations of this thesis are: (i) Characterization of the duration and influence of spatial legacies on forest disturbances and sustainability; (ii) Development of a dynamic spatial forest simulation model that includes distinct successional rules that respond to different types of disturbance and shifts in disturbance regimes; and, (iii) Development and application of a wavelet-based significance testing framework to identify key scales of expression in forest spatial patterns. These innovations provide a scientific basis for landscape level forest management strategies designed to reduce the long term impacts of defoliating insects and to meet multiple objectives.

Understanding the use of habitat by large carnivores in the presence of ever increasing anthropogenic disturbance is crucial to managing threatened species. In the foothills of the Rocky Mountains in west-central Alberta, Canada the grizzly bear (Ursus arctos) faces such disturbance, and is especially susceptible due to their low fecundity and large home ranges. Grizzly bear mortality increases with proximity to human disturbance, leading to the conclusion that anthropogenic forest disturbance is incompatible with successful grizzly bear habitat The purpose of this research is to evaluate grizzly bear habitat use as it relates to forest disturbance. The general approach was to quantify grizzly bear habitat use and compare to an expectation of use calculated through conditional randomization. The research involved two distinct analyses. First, grizzly bear use of natural edges (transitions between land cover classes) and anthropogenic landscape edges (roads, pipelines, and forest harvests) was quantified and compared between seasons and sex. Females were found to use anthropogenic edges more than natural edges, whereas males used natural edges more. Despite the increased mortality threat arising from increased human access around anthropogenic disturbances, female grizzly bears are using anthropogenic edges more than natural edges, meaning anthropogenic edges may not be incompatible with successful grizzly bear populations. Knowing that female grizzly bears use anthropogenic edges more allows managers to limit access to areas with specific edges desirable to female bears. While creating more disturbances is not the solution to managing for better grizzly bear habitat, limiting human access to areas of beneficial edge could decrease mortality risk. Knowing that grizzly bears use edges, the second analysis quantified use of forest disturbances of varying ages, and determined what disturbance characteristics drive grizzly bear selection of forest disturbances. A 40-year forest disturbance dataset was generated through image differencing of the tasselled cap angle transformation of Landsat imagery (MSS, TM, ETM+). Disturbances were grouped into decades, and compared. Disturbances were labelled as selected or not selected through a randomization process, and selected disturbances were compared to not-selected disturbances using four landscape metrics: disturbance size, disturbance elevation, average tasselled cap transformation greenness, and distance from disturbance to nearest human settlement along a road network. Results indicate that bears select for larger disturbances in all seasons. Females select for disturbances with low remotely-sensed greenness in all seasons, where males select for disturbances with low remotely-sensed greenness in the spring and fall, but high remotely-sensed greenness in the summer. Females select for disturbances at a consistent elevation, whereas males show seasonal variation. Both sexes avoid the most recent disturbances from the 2000s. Females show greater selection of disturbances in the summer and fall, whereas males select disturbances in the fall the least. Knowing that bears select for large disturbances, and females select disturbances at a consistent elevation, forest managers can limit human access to these areas in order to limit human and bear interactions and reduce mortality risk. / Graduate

Forest disturbances and the spatial patterns they create affect ecosystem processes through their influence on forest vegetation from individual trees to landscapes. In the boreal and mixed-wood forests of eastern Canada the main agents of disturbance are logging, fire, and defoliation by the spruce budworm (SBW, Choristoneura fumiferana). These disturbances are similar in that they remove forest biomass and influence forest succession but also distinct in that logging creates patterns that are different than those created by natural disturbances. All disturbances are indirectly linked to each other through their mutual effects on forest spatial structure and succession. Through such feedbacks, spatial disturbance legacies can facilitate or constrain further disturbances, including forest management. Surprisingly, the long term spatial consequences of interactions among multiple natural and anthropogenic disturbances remain largely unexplored. This thesis investigates how, and at what spatial scale, legacies in forest composition and age structure influence natural disturbance dynamics, and how natural disturbances constrain forest management. I address four specific questions: (i) For how long do spatial legacies of different forest management strategies persist on the landscape? (ii) How do interactions among logging, fire, SBW, and succession affect timber availability and long term forest patterns in age and composition? (iii) How do these patterns differ from those created by each disturbance individually? And, (iv) How can management be used to reduce the extent and severity of fires and SBW defoliation through the manipulation of forest structure? The key scientific innovations of this thesis are: (i) Characterization of the duration and influence of spatial legacies on forest disturbances and sustainability; (ii) Development of a dynamic spatial forest simulation model that includes distinct successional rules that respond to different types of disturbance and shifts in disturbance regimes; and, (iii) Development and application of a wavelet-based significance testing framework to identify key scales of expression in forest spatial patterns. These innovations provide a scientific basis for landscape level forest management strategies designed to reduce the long term impacts of defoliating insects and to meet multiple objectives.

Tree-ring data serves as a chronicle of the past environment and provides long-term records about climate variations, volcanic eruptions, glacial activity and many others processes. Over the past few decades, dendrochronology has become common in studying disturbances. This thesis is focused on release detection methods (i.e. abrupt growth after death of neighbouring tree(s)) and their application. The presented review showed that despite the some uncertainties in methodological approaches, release detection is a reliable tool for forest disturbance reconstruction. In this thesis, release detection was applied in various forest ecosystems for reconstruction of disturbances and their effects. The achieved results importantly contribute to the understanding of the ecological processes concerning forest management, long-term changes in natural forest ecosystems, forest diversity and the impact of global changes.

In this study, I attempted to evaluate the impact of two forest disturbances on the soil temperature and humidity in spruce forest. The spruce forests were attacked by bark beetle in the Březník area 17 years ago. Two types of management were applied after the bark beetle attack. The first approach was clear cutting and removing dead trees. The second approach was non-interventional and this zone was left to natural succession. This study compares differences in daily temperature amplitude and volumetric soil humidity between both types of management. I tried to evaluate whether the soil temperature and humidity conditions are explained more by influence of the management or by vegetation cover. Results showed significant difference in daily temperature amplitudes. Temperature amplitudes are about 49 % higher in clear cut areas than in areas with natural succession. Differences are insignificant in soil humidity conditions. The influence of the vegetation on soil temperature and humidity is insignificant. I, too, compared soil temperature and humidity from Březník areas (17 years after disturbance) and Prameny Vltavy areas where the spruce forest decayed recently.

The uprooting of trees due to high winds, or blowdown, is a common occurrence throughout the world. Rare, large scale blowdown events have the ability to drastically alter forest landscapes on a timescale of hours. Alone or when combined with other forest disturbances such as fires and insect outbreaks, blowdowns have the potential to modify existing watershed characteristics. Little information is known about how large-scale blowdowns affect the physical environment in general and watershed-wide sediment yield and deposition rates in particular. The few studies that have taken place have yielded inconclusive or somewhat contradictory results. Given the large scale of some events and the potential impact of such events it is important that the geomorphological effects of blowdowns be better understood, not only from a basic process but also from an applied perspective. Lakes receive and store a significant fraction of the disturbed sediment formerly found in the soil column and lake sediments have proven to be reliable and accurate records of sedimentation characteristics within their catchments. For the purpose of this study, it was hypothesized that areas subjected to blowdown will have increased erosion rates. It was also hypothesized, that lakes within blowdown areas will be subjected to accelerated sedimentation rates following events. In order to test these hypotheses and isolate the effects of a blowdown on sedimentation rate three small mountain lakes in the Mt. Zirkel Wilderness Area, Colorado were cored. The lakes selected consist of a control lake with no known recent history of blowdown in its watershed and two lakes that receive direct runoff from watersheds and slopes that were affected by a major blowdown event in 1997, the Routt-Divide Blowdown. One core was dated using the 210Pb method and multiple cores were analyzed for organic and inorganic matter concentrations to determine if changes in sedimentation rates and/or sediment compositions occurred following the event. In the case of the two lakes studied that had catchment slopes affected by blowdown, somewhat surprisingly, no significant change was observed with respect to sedimentation rates or sediment composition. In fact, sedimentation rates obtained from the dated core exhibited a decreasing trend that began decades prior to and continued through the blowdown event. This suggests that in the area affected by the Routt-Divide Blowdown it is likely that long-term changes in climate and the effect these changes have on the amount and type of vegetation present are the dominant influence on sedimentation rates, and that the Routt-Divide Blowdown of 1997 did not increase the rates. Based on further evaluation of the sites and the event it appears that slope characteristics and treefall orientation may be significant factors controlling the amount and type of disturbed sediment that moves downslope. In the case of future large-scale blowdowns, where their effect on water quality or sedimentation rates is in question, dominant treefall orientation with respect to slope should be an integral part of initial assessment, especially in remote area, and be considered when interpreting data from any similar study.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第18619号 / 情博第543号 / 新制||情||96(附属図書館) / 31519 / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 守屋 和幸, 教授 吉川 正俊, 准教授 小山 里奈 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Bruce Peninsula National Park (BPNP) clears a 2 m swath of trees on the boundary in order to make it clear when one is entering the park from any neighbouring land; this in particular aims to protect the park and its inhabitants from illegal actions such as hunting and logging. This study looks at the ecological effects of this practice by measuring various microclimate variables and the abundance of eastern redback salamanders (Plethodon cinereus) on the boundary and comparing these measurements to parallel transects at 5, 10, 15, 20, and 40 m. Because it is a small linear development, it is then compared to other types of linear developments, such as roads, trails, and pipelines. The microclimate variables of air temperature, slug abundance, canopy cover, soil pH, total cover area, litter depth, and relative humidity were all significantly affected (p<0.05) up to 10 m into the adjacent forest, indicating that the cleared boundaries do change the surrounding microclimate. Soil pH, downed woody cover area, litter depth, and canopy cover were significantly affected (p<0.05) up to 5 m away from the boundary. Sixty hectares, or 0.4%, of the land area of BPNP is thus affected by the microclimate changes caused by the cleared boundary. These effects are similar to those found for other narrow, vegetated linear developments such as trails. Over double the number of salamanders were found on the boundary as compared to in the forest; this is due to higher cover area availability on the cleared boundary from the felled trees. Therefore, the boundary does not act as a barrier to eastern redback salamander movement, nor does it fragment the local population. Salamander abundance was best explained by the amount of cover area, snail abundance, and the dominant type of vegetation present along transects. It was also found in an additional study that salamander abundance tended to increase with increasing days since the last precipitation event, contrary to most woodland salamander monitoring protocols and methods. The boundaries were seen also to be used by hunters and recreationalists through incidental observations of human disturbance. This increased access to remote areas of the park through use of the cleared boundaries is an issue that requires further study, as the boundary itself may be leading to an increase in illegal activity. Recommendations to BPNP include leaving downed woody cover on the boundary, minimizing the boundary width, reducing lines of sight, decreasing accessibility, increasing landowner and park staff education, communicating with adjacent landowners, and securing funding to complete and maintain the boundary clearing.

Bruce Peninsula National Park (BPNP) clears a 2 m swath of trees on the boundary in order to make it clear when one is entering the park from any neighbouring land; this in particular aims to protect the park and its inhabitants from illegal actions such as hunting and logging. This study looks at the ecological effects of this practice by measuring various microclimate variables and the abundance of eastern redback salamanders (Plethodon cinereus) on the boundary and comparing these measurements to parallel transects at 5, 10, 15, 20, and 40 m. Because it is a small linear development, it is then compared to other types of linear developments, such as roads, trails, and pipelines. The microclimate variables of air temperature, slug abundance, canopy cover, soil pH, total cover area, litter depth, and relative humidity were all significantly affected (p<0.05) up to 10 m into the adjacent forest, indicating that the cleared boundaries do change the surrounding microclimate. Soil pH, downed woody cover area, litter depth, and canopy cover were significantly affected (p<0.05) up to 5 m away from the boundary. Sixty hectares, or 0.4%, of the land area of BPNP is thus affected by the microclimate changes caused by the cleared boundary. These effects are similar to those found for other narrow, vegetated linear developments such as trails. Over double the number of salamanders were found on the boundary as compared to in the forest; this is due to higher cover area availability on the cleared boundary from the felled trees. Therefore, the boundary does not act as a barrier to eastern redback salamander movement, nor does it fragment the local population. Salamander abundance was best explained by the amount of cover area, snail abundance, and the dominant type of vegetation present along transects. It was also found in an additional study that salamander abundance tended to increase with increasing days since the last precipitation event, contrary to most woodland salamander monitoring protocols and methods. The boundaries were seen also to be used by hunters and recreationalists through incidental observations of human disturbance. This increased access to remote areas of the park through use of the cleared boundaries is an issue that requires further study, as the boundary itself may be leading to an increase in illegal activity. Recommendations to BPNP include leaving downed woody cover on the boundary, minimizing the boundary width, reducing lines of sight, decreasing accessibility, increasing landowner and park staff education, communicating with adjacent landowners, and securing funding to complete and maintain the boundary clearing.

British Columbia’s current mountain pine beetle epidemic has led to salvage and mitigation harvesting strategies intended to slow the dispersal of beetles, and recover economic value from infested timber stands. These resulting harvesting strategies will alter the spatial pattern of forest landscapes in impacted regions, often resulting in forest fragmentation. As a result, wildlife habitat, hydrologic regimes, local carbon budgets, and soil dynamics, amoung other ecological properties, are expected to be negatively impacted. Monitoring of forest fragmentation in Canada is now required for the Montreal Process, an international forest monitoring policy. Effective methods that quantify changes in forest fragmentation, the breaking up of forest land cover into smaller, and more numerous parts, are required to meet forest monitoring objectives. This research provides two new methods that build upon existing approaches widely used for quantifying the spatial patterns of landscape features (i.e., landscape pattern indices). The first approach I demonstrate aids the quantification of forest pattern change over two time periods, by accounting for the impact of composition on spatial configuration. The value of this method is demonstrated using a case study that highlights the impacts of forest harvesting, associated with insect salvage and mitigation activities. This method allows landscapes that have changed primarily in composition to be distinguished from those that have experienced large configurational change. In the second approach I use multivariate cluster analysis for regionalization (the grouping of objects in space), and identify regions within a study area where increased fragmentation is observed. Regions delineated based on forest spatial pattern can be linked to underlying processes. Ancillary information (e.g., elevation) can be used to identify areas where observed forest pattern is due to underlying physiological features. Pattern indices (e.g., patch perimeter-area ratio) can be used to distinguish between patterns arising from forest disturbance that is likely natural (e.g., fire) or anthropogenic (e.g., harvest activity) in origin. The methods presented in this thesis may be most appropriate when observed changes in landscape pattern can be attributed to substantial changes in landscape composition.