Depuis quelques années la sylviculture intensive prend une grande ampleur afin de rapprocher la source de fibres des usines, d'accroître la productivité des plantations, et de diminuer la pression de coupe sur les forêts naturelles. Toutefois un débat sur le type d'aménagement optimal des plantations oppose l'aménagement mono- et pluri-spécifique. Il est important de mieux comprendre le fonctionnement de ces écosystèmes pour en effectuer une bonne gestion et d'optimiser les services écosystémiques que ces plantations fournissent. La décomposition des litières et le recyclage des nutriments sont des processus complexes essentiels au fonctionnement des écosystèmes. Ainsi mon projet de thèse visait à mieux comprendre l'influence de la mixité de deux essences forestières, à savoir l'épinette blanche et le peuplier hybride, en comparaison à des plantations pures sur le processus de décomposition des litières et le stockage de carbone. Les résultats de cette étude ne montrent pas d'amélioration du processus de décomposition avec le mélange du peuplier et de l'épinette ou de leurs litières. En revanche, le mélange de ces deux espèces en plantation tamponne les effets contrastés du peuplier et de l'épinette observés dans les plantations monospécifiques. De plus, le stockage de carbone et la productivité du peuplier sont améliorés dans les plantations mixtes par rapport aux plantations monospécifiques. Les herbacées semblent être bénéfiques pour la diversité d'organismes et favorisent la libération d'azote des litières d'arbres. Cet aspect pourrait contrebalancer l'effet négatif de la présence d'herbacées qui entrent en compétition avec les arbres pour les ressources. / The use of trees under intensive management is particularly important for rapid fibre production and for reduce cutting pressure on natural forests in boreal regions. However, a debate on the best type of plantation management opposes the mono-and pluri-specific management. Despite the possible antagonistic effects on productivity, it seems that mixed plantations would have benefits on soil properties, environmental stability, but also to maintain biodiversity and aesthetic value. It is important to better understand the functioning of these ecosystems to make good management in order to optimize ecosystem services of these plantations. Litter decomposition and nutrient cycling are essential process for the ecosystems functioning. My thesis project was to better understand the influence of the mixing of two tree species planted in comparison to monospecific plantations, namely white spruce and hybrid poplar, on the litter decomposition process and carbon storage. The results of this study showed no improvement in the decomposition process with the mixture of poplar and spruce in plantation or by their litters mixture. However, the mixture of the two species in plantation buffers the contrasting effects of poplar and spruce observed in monospecific plantations. In addition, carbon storage and productivity of poplars are improved in mixed plantations compared to monospecific plantations. Herbaceous litter appears to be beneficial for the abundance of organisms and promote the release of nitrogen from tree litter. This could offset the negative effect of the presence of grasses that compete with trees for resources.

Différents modes de réhabilitation forestière des sites agricoles abandonnés peuvent affecter la diversité végétale des sites. L’analyse des traits fonctionnels des plantes pourrait permettre de révéler l’effet des différentes pratiques sylvicoles suggérées. L’étude porte sur deux communautés de friches arbustives ayant reçu la plantation de trois espèces d’arbres feuillus. La préparation des sites par un débroussaillement total ou par bande, combinés ou non d’herbicide offre l’occasion de mesurer l’effet de ces traitements sur la distribution des traits fonctionnels des communautés végétales après onze ans. Les résultats d’une analyse du 4e coin montrent un effet des traitements sur les traits fonctionnels des communautés et ce, davantage sur le site où la transmission de la lumière est supérieure. Un débroussaillement par bande permet un recul successionnel moins grand que total, avec la présence de plusieurs traits fonctionnels liés aux espèces de fin de succession tels que les phanérophytes et les espèces à semences de plus grande taille Un débroussaillement total résulte plutôt en une présence accrue des espèces exogènes et des intolérantes à la lumière. L’application d’herbicide influence peu la distribution des traits mais augmente la croissance du noyer noir lors de débroussaillement total et dans une moindre mesure lors de débroussaillement en bande. Le peu de différenciation significative de survie et de croissance en hauteur des arbres entre les traitements permet de proposer un débroussaillement par bande plutôt que total, afin de diminuer le recul successionnel, tout en nécessitant un moins grand recours à l’herbicide. / Different kinds of forest rehabilitation on abandoned farms could have an impact on plant diversity. Plant functional traits analyses could reveal effects of different management strategies. Two shrublands were planted with three hardwood species. They received the following treatments in 1998: total or striped clearing, with or without herbicide. The goal of this study is to determine the effects of these treatments, 11 years later, on functional traits distribution within the plant communities. According to a fourth corner analysis, the functional traits communities variation between treatments was significant, even higher, for the shrubland that had higher light availability. Striped clearing caused a less important successional retreat than total clearing, selecting for traits representative of shaded habitats like the presence of phanerophyte species and species with big seeds. Total clearing allowed a greater light availability in the following years, which selected for functional traits such as presence of exogenous and shade-intolerant species in the sampling units. Herbicide application had few effects on traits but increased black walnut growth when total clearing was applied, as well with strip clearing, but to a lesser extent. With low differentiation of tree growth and survival between treatments, we suggest using the striped clearing on planted shrublands in order to decrease the succession decline, while minimising herbicide use and their impacts on the surrounding plant communities.

This research was conducted to determine the main influences and physical factors of land suitability for rubber plantation in the Nam Dong district, Thua Thien Hue province. Six factors such as soil type, soil texture, soil thickness, slope, soil pH and soil organic matter content were considered. Results indicate that soil thickness is has the highest role on the land suitability analysis while soil pH has the lowest. The physical land suitability of rubber plantation was divided into 4 levels: very suitable (10.1%), suitable (15.5%), slightly suitable (3.6%), and currently not suitable (70,8%). This research provides important information for rubber cultivation in projected agricultural land use planning of the Nam Dong district. / Nghiên cứu này được thực hiện nhằm xác định sự ảnh hưởng của các yếu tố tự nhiên đến sự thích nghi đất đai của loại hình sử dụng đất trồng cây cao su trên địa bàn huyện Nam Đông, tỉnh Thừa Thiên Huế. Có 6 yếu tố được xem xét trong nghiên cứu này bao gồm: loại đất, thành phần cơ giới, tầng dày canh tác, độ dốc, độ chua và hàm lượng mùn trong đất. Kết quả nghiên cứu chỉ ra rằng tầng dày canh tác là yếu tố có ảnh hưởng lớn nhất đến việc sử dụng đất trồng cây cao su, trong khi đó độ chua là yếu tố có ảnh hưởng ít nhất. Sự thích nghi tự nhiên của loại hình sử dụng đất trồng cây cao su được chia thành 4 mức độ bao gồm rất thích nghi (10,1%), thích nghi (15,5%), tương đối thích nghi (3,6%) và hiện taị không thích nghi (70,8%). Nghiên cứu này cung cấp những thông tin cần thiết và hữu ích cho việc quy hoạch sử dụng đất trồng cây cao su trên địa bàn huyện Nam Đông.

Pinus radiata is the dominant species of the plantations forests in New Zealand. The forest industry in New Zealand is heavily dependant on it. However, Pinus radiata can develop wood quality flaw called 'intra-ring checking'. The checks or splits appear in wood during kiln drying and usually affect the earlywood region of the wood. It lowers value of appearance grade timber leading to huge economic loses for the forest industry. This thesis presents a study that was undertaken as a part of ongoing collaborative work that is being carried out to understand wood quality issues in Pinus radiata, with a vision of improving its wood quality. This study was a part of that effort and was conducted with an aim to gain an insight into intra-ring checking, and the process of xylogenesis in Pinus radiata. The investigations for this study were carried out in two steps. The first step was to understand intra-ring checking. The location of intra-ring checking was determined by observing the checks using various microscopy techniques. Scanning electron microscopy confirmed that checking was as an intercell failure that usually occurs at the cm1/S1 boundary. A comparative study was also conducted to see if the checked wood had some inherent properties that made it more susceptible to checking. It was found that checking could be influenced by tracheid geometry and cell wall thickness. If the wood had large tracheids with thin walls, it was more likely to develop checks during drying. Lignin distribution in the cell wall layers was also seen to play an important role in checking. Lower lignin levels and disruption in the pattern of lignification of the cell wall layers increased the tendency of the wood to develop checks. Similarly, it the tracheids have larger pits then their tendency to check increases. Structural features that disrupt the uniformity of the interlocking pattern of the tracheid such as rays and resin canals could also play a role in checking. Checked wood tends to have more surface area occupied by ray tissue. However, resin canals do not seem to be directly involved in checking, though their arrangement could indicate disturbances during xylogenesis. The second step was to understand the process of xylogenesis in Pinus radiata especially with respect to the influence of auxin and boron on it. Nutrient and organ culture methods were manipulated and successfully used to study xylogenesis. An exhaustive comparative study was carried out to observe and measure selected wood properties. Microscopy and image analysis revealed that auxin and boron changes in the medium led to the alterations in the cell division, expansion and lignification. However, the analysis of the measurements and the observations displayed complex 'between-tree' and 'within-culture variations'. Clear trends did not emerge from the analysis hence, a confident conclusion on the association between auxin, boron and lignification could not be drawn from this organ culture study. The study has added to the knowledge about checking and wood properties associated with it. A new tool of organ culture had been established that can hlep future research on the process of xylogenesis in Pinus radiata.

Compared to natural forests, fast-growing plantations of exotic species such as Pinus radiata are often perceived as marginal habitat or unsuitable habitat for most native species. By studying Coleoptera (beetles) in a variety of landscape elements (pasture, native forest and different aged Pinus radiata stands) in a highly modified and fragmented landscape in New Zealand I aimed to determine the value of exotic plantation forests for native biodiversity, and how these species are affected by different sized clearfell harvest areas. Pitfall trap sampling of beetles showed that plantation forest stands can provide suitable complimentary habitat to native forest for many species. Rarefied species richness of Carabidae, Scarabaeidae and Scolytinae was not significantly different between habitats, however, habitat types differed significantly in their beetle community composition. Comparing different production habitats, Pinus radiata stands had a beetle community composition most similar to native forest. However, a small minority of species, e.g., Dichrochile maura, were restricted to native forest habitat highlighting the importance of retaining indigenous ecosystems within plantations. Unlike human modified habitats, native forests did not provide suitable habitat for exotic species. Clearfell harvesting is controversial and its impact on biodiversity is a key constraint for many forest certification programs, such as that administered by the Forest Stewardship Council (FSC). Despite this, no replicated manipulative experimental studies of the impact of different sized clearfell harvest areas on biodiversity have been undertaken at scales relevant to the New Zealand forest industry. One potential model of the impact of different clearfell harvest sizes is the concept of a threshold size. A threshold scenario may occur where clearfell harvest impacts increase at a rate disproportionate to the change in clearfell size over a small range of harvest areas, but impacts remain relatively unchanged either side of the threshold zone. I sampled Coleoptera in experimentally created 0.01, 0.05, 0.5, 5.0, 50 and 500 ha clearfells within Pinus radiata plantations in the central North Island of New Zealand. The wide range of clearfell harvest sizes, including some very small areas, such as 0.01 ha was instigated in an attempt to document potential clearfell harvest size thresholds. Rarefied native beetle species richness was higher in harvest areas compared to adjacent mature plantation stands. The beetle species richness in 5 ha and 500 ha harvest areas was significantly greater species than that in small 0.01 - 0.5 ha harvest areas. Although, the high beetle diversity recorded in 500 ha clearfells should be treated with caution due to confounding spatial autocorrelation. The degree of change in beetle community composition increased with increasing clearfell harvest area. Beetle assemblages in large harvest areas were less similar to their paired adjacent mature forest than smaller harvest areas. Although, constrained multivariate ordination techniques did show a short-term change in beetle species composition between recently clearfelled harvest areas of as little as 0.05 ha and adjacent mature P. radiata stands. The colonisation by open-habitat disturbance-adapted species was a key driver of this change, some species dispersed into clearfelled stands in significant densities within days post-harvest. Overall, there were no distinct short-term trends to the change in species richness as a function of increasing harvest area that would suggest an ecological impact threshold response. If short-term outcomes of clearfell harvesting are ameliorated by successful recolonisation, the long-term spatial arrangement of different aged stands becomes more important for the maintenance of biodiversity at the landscape level than short-term consequences of harvesting. By sampling selected beetle taxa in 1, 2, 4, 8, 16 and 26 year-old stands, I found that the abundance of seven out of eight of the species selected for analysis recovered to levels similar to those in adjacent mature forest within the timeframe of a single harvest rotation. Individual species utilised different aged stands, indicating different life-history strategies. For example, open-habitat, disturbance-adapted species such as Cicindela tuberculata and Sitona discoideus were prominent in young stands, and forest species such as Pycnomerus sophorae and Paracatops phyllobius were highly abundant in older stands. These alternative life-history strategies highlight the benefits of maintaining a mixture of different aged stands to increase biodiversity at the landscape level. This thesis fills an important gap in our knowledge of biodiversity in production landscapes. I show that plantation forests have value as complimentary habitat to native forest and they make an important contribution to the maintenance of biodiversity at the landscape level. Although clearfell harvesting is a severe disturbance to the forest ecosystem, the long-term recovery of beetle populations suggests that harvesting is not the key limiting factor to the enhancement of biodiversity in the plantation forests studied. This unusual situation is possibly the result of prior land-use history, as many plantations were established on degraded pastoral land, and harvest-sensitive species are unlikely to have survived this initial land-use change. As such, the severity of the long-term impacts of clearfell harvesting on biodiversity are likely to be context specific and will vary accordingly. The importance of spatial heterogeneity of habitat elements, including different aged plantation stands and native forest remnants, needs to be investigated in more detail to determine what limits biodiversity in this plantation landscape. Key points to consider are the proximity to, and proportion of, native forest cover in the landscape and the degree of connectivity among native remnants. It is these landscape-level attributes that may determine biodiversity at a regional scale, and more emphasis should be placed on landscape scale factors and there interaction with stand specific forest management practices. For example, the spatial mosaic of harvesting areas may need to be of a finer-scale when there are fewer native remnants within the landscape.

Tyrimų objektas – Jonavos r., netoli nuo azotinių trąšų gamyklos AB „Achema“ Neries upės šlaite įrengtas nuotykių parkas UAB „Lokės pėda“. Tyrimų tikslas – paruošti „Lokės pėda“ parko teritorijos tvarkymo ir želdinimo kultūriniame kraštovaizdyje ekologinius principus. Šiam tikslui pasiekti spręsti tokie uždaviniai: (1) išanalizuoti informaciniai šaltiniai ir mokslinė literatūra; (2) įvertintas oro užterštumas AB „Achema“ teršalais; (3) nustatytas dirvožemių trofiškumas ir degradacija; (4) įvertinta medžių būklė; (5) tirti medynų ir gyvosios dirvožemio dangos pokyčiai. UAB „Lokės pėda“ nuotykių parko, kuris yra tik 1,4 km atstumu į šiaurę nuo AB „Achema“, oras gali būti užterštas NO2 ir NH3 dujomis. Parko šlaite augančiame miške yra vietų, kuriose lankytojai yra sunaikinę dirvožemio žolinę dangą ir miško paklotę. LAMMC Miškų institute atliktos analizės parodė, kad dėl to padidėja dirvožemių viršutinio mineralinio sluoksnio tankis, šis sluoksnis yra užteršiamas sieros junginiais, sumažėja dirvožemio pasotinimas maisto medžiagomis, organine anglimi ir suminiu azotu. Pagal lajų defoliaciją įvertinus šlaito miške medžių būklę, nustatyta, kad parke ir šalia augančiame miške geriausios būklės yra paprastieji klevai ir mažalapės liepos, o paprastieji ąžuolai ir paprastieji uosiai džiūsta. Palyginus su natūraliu mišku, parko trasose ir tarp trasų skirtingų rūšių medžių būklė nėra blogesnė. Tačiau parke yra medžių, kurie turi mechaninius pažeidimus: nubrozdinimus ir neteisingai... [toliau žr. visą tekstą] / The object of research – the treetop adventure park JV „Lokės Pėda“ settled on the slope of river Neris in Jonava district near nitrogen fertilizer plant JV „Achema“. The research aim – to prepare the landscape management and plantation ecological principles in the park. There following objectives were set up: (1) to analyse the informative sources and scientific literature; (2) to evaluate air pollution by emissions from JV “Achema”; (3) to determine soil fertility and degradation; (4) to evaluate tree condition; and (5) to estimate the changes in stand and ground vegetation cover. The treetop adventure park JV „Lokės Pėda“ what is situated only 1.4 km north from JV “Achema”, could be polluted with NO2 and NH3. Thus, in the forest down the park slope there are places where the visitors have destroyed ground vegetation cover and forest litter. According to the obtained research data the bulk density of the uppermost layer of mineral soils is increasing, the topsoil is polluted with sulphur compounds, the soil decreases in saturation of the nutrients, organic carbon and total nitrogen. Evaluating of the tree defoliation down the slope it was estimated, that in the park and the forests close to the park the trees of Acer platanoides and Tilia cordata are in beneficent condition. While, the trees of Quercus robur and Fraxinus excelsior are dying. But if to compare with natural forests, in the park tracks and between the tracks the decline in different tree condition is not... [to full text]

Tikslas Vienuolikos rinktinių medžių klonų sėklinių palikuonių ir medžių išaugintų iš vietinių sėklų, kiekybinių ir kokybinių parametrų palyginimas. Objektas Želdiniai įveisti 1 ha plote 1980 metais Šakių u-jos Klevinių g-je pagal doc. J. Danusevičiaus projektą. Sodinimui plotas parinktas 140 kv. 6 skl. (1978 metų plynai iškirstoje degvieteje). Ploto dirvožeminė-¬tipologinė grupė - Nbl. Metodika Matavimai atlikti laikinuose nevienodo ploto tyrimo bareliuose, apribotuose eglių eilėmis. Visuose bareliuose išmatuoti visi ten augantys medžiai. Medžių aukštis ir aukštis iki žalių šakų matuotas 0,5 m tikslumu, skersmuo - 1,3 m aukštyje 1 cm tikslumu. Kiti parametrai buvo vertinami vizualiai. Stiebo tiesumas, šakų storis, šakų prisegimo kampas ir medžių būklė vertinti 5 balų sistema. Taip pat buvo vertinta medžių priklausomybė Krafto klasėms (I-V). Matavimų duomenys apdoroti Statistica programa. Rezultatai Nustatyta, kad 30 metų amžiuje pagal medžių aukštį geriausi yra 4 ir 8 šeimų medžiai (19,6 – 16,6% aukštesni už kontrolinius želdinius), blogiausi – 14 ir 9 šeimų medžiai. Didžiausią stiebų skersmenį turi 10 ir 4 šeimų medžiai (14,2 – 12,7% storesni už kontrolinius želdinius), o mažiausią skersmenį – 14 ir 7 šeimos medžiai. Beveik analogiškais rodikliais šios šeimos pasižymėjo ir 18 metų amžiuje. Pagal išlikimą ir sukauptą tūrį trys geriausios šeimos produkuoja 176 – 145 m3/ha ir tuo 1,9-1,6 karto lenkia vietinės kilmės medžius bei 2,8-2,3 karto - blogiausios 3 šeimos medžius... [toliau žr. visą tekstą] / Purpose To compare qualitative and quantitative data of eleven selected clones of descendant seed and trees, that were cultivated from local seed. Object Afforestation that was cultivated in 1 hectare in 1980 in Kleviniai forestry of State forest of Sakiai by the project of associate professor J. Danusevičius. Plantation was selected in the area in 140th block and 6th plot (in the area that was entirely cut down in 1978). Metods Measurements are made in temporary areas that are not of the size and are surrounded by rows of fir trees. All trees that grow in these areas were measured. Height of trees and height up to green knocks are measured by the precision of 0,5 meter, diameter in 1,3 meters high- by the precision of 1 centimeter. Other measurements were evaluated visually. Straightness of stem, thickness of knocks, angle between stem and knock and the condition of trees were evaluated using a system of 5 grades. Dependency to Kraft classes (I-V) was also evaluated. Data of measurements was processed by Statistica program. Results The study showed that in the age of 30 years the best are 4th and 8th clones' tree families (19,6 – 16,6% higher than controlled plans), the worst – 14th and 16th clones' tree families. 10th and 4th clones' tree families have the biggest diameter of stem (14,2 – 12,7% thicker then controlled plans), and the smallest diameter has 14th and ir 7th clones' tree families. These tree families had almost the same measurements also in the ages... [to full text]

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

An examination of the Shirley Plantation Collection, Hill Carter, Mary B. Carter, their children, the plantation workers and their wardrobe between 1825 and 1835.

This thesis provides an analysis of Shirley Plantation’s operation as a historic house museum from 1894 to the present period, and the Carter family’s dedication to keeping the estate within the family. The first chapter examines Shirley Plantation’s beginnings as a historic house museum as operated by two Carter women, Alice Carter Bransford and Marion Carter Oliver, who inherited the property in the late nineteenth century. The second chapter explores Shirley Plantation’s development as a popular historic site during the mid-twentieth century to the early part of the twenty-first century, and compares the site’s development to the interpretative changes that had been occurring at Colonial Williamsburg. The third chapter analyzes and critiques Shirley Plantation’s present interpretative focus as a historic site, with the fourth chapter offering suggestions for developing an exhibition that interprets the history of slavery at the plantation.