A comparing study of planting spots and terrain impact in different types of terrain.

The Lower Coastal Plain of the southeastern United States is a major wood producing region. The region is characterized by a combination of nearly-level topography, poorly-drained soils, and high rainfall, which results in a perched water table in some soils that inundates the surface several times each year. Harvesting timber under wet site conditions often results in extensive soil compaction, rutting, soil displacement, and waterlogging. Forest managers are concerned that these visually-displeasing soil disturbances may cause site damage and reduced productivity. These concerns were addressed in an operational-scale field experiment conducted in South Carolina. The objectives of this experiment were to determine: (i) if soil disturbance changes key soil properties and processes; (ii) if soil disturbance reduces loblolly pine productivity; and, (iii) if disturbance can be mitigated with site preparation practices? Three 20-ha, 20-yr-old loblolly pine (Pinus taeda L.) plantations were harvested under wet and dry conditions to create a broad gradient in soil disturbance. Within each harvested plantation, a subset of 3-ha plots were site prepared by either bedding, or mole-plowing plus bedding, then all sites were established as 3rd -rotation pine plantations. Prior to site preparation, each plot was classified and mapped using a 5 by 5 soil disturbance (none to churned) by organic debris (none to slash piles) classification matrix. Within each plot, data were collected on several soil physical, chemical, and biological properties over a 2-yr period following site preparation. Key soil properties were integrated into a Soil Quality Index (SQI) and compared to aboveground productivity of 2-yr-old loblolly pine trees growing on closely-spaced (30 by 30 cm) bioassay plots planted across the gradient of soil disturbance. The soil physical properties were used to determine the least limiting water range (LLWR), the range in soil water content within which root growth is not limited. Soil compaction and deep rutting reduced the LLWR. Retention of logging slash improved the LLWR for compacted and rutted soils. Site preparation improved the quality of the soil physical environment across all levels of soil disturbance. Soil disturbance had no effect on soil chemical or biological properties as evidenced by no change in soil pH, ECEC, base saturation, available P, or net N mineralization with disturbance. The base saturation exceeded 80 % on all sites, with Ca saturation controlling soil pH. The high base saturation buffered any redox-induced changes in soil chemistry that would have resulted from disturbance. The results showed that high fertility is an important mechanism for buffering the potentially-negative effects of soil disturbance on the soil nutritional environment. Site preparation changed soil chemical properties, but the changes were probably associated with tillage effects on organic matter and clay content, not redox processes. The SQI showed that surface soil compaction and deep rutting reduced soil quality, mainly by decreasing the LLWR and aeration depth. Site preparation mitigated the effects of most disturbances on soil quality, evidenced by similar aboveground biomass production among soil disturbance classes after bedding. A regression model was developed for predicting aboveground biomass production as a function of SQI. SQI explained 73 % of the variation in aboveground biomass production. The regression model showed that compression tracks and rutting decreased aboveground biomass production compared to undisturbed soils. The long-term effect of these disturbances on productivity will depend on natural soil recovery processes. However, these early results suggest that compaction and rutting should be minimized on similar sites, especially if sites will not be bedded before reforestation. The mole-plow / bedding treatment increased aboveground biomass production, indicating that this experimental treatment may be a viable practice for enhancing productivity. / Ph. D.

The main goal of this thesis was to improve our understanding of the long-term effects of establishment treatments and climate change on lodgepole pine and white spruce growth in the western boreal forests. My dissertation also investigated the combined effects of climate and competition on white spruce and trembling aspen growth in boreal mixtures. In the first part of the thesis I evaluated the effects of site preparation treatments on growth of lodgepole pine and white spruce in north-eastern British Columbia. Results indicate that mechanical site preparation can provide yield gains of up-to 10 percent for pine and spruce at 60 and 80 years, respectively. These stands are showing a Type 1 growth response which implies that the treatment effect will eventually cease 90-100 years after planting. In the second part of the thesis I explored pine and spruce growth in relation to past climate and site preparation. Results indicate that up-to 45% and 37% of the respective variation in spruce and pine growth can be explained by selected climatic variables. Future projections indicated that height growth of young pine plantations in the sub-boreal zone could benefit (in the short term) from longer growing seasons by up-to 12% on untreated stands. Untreated young spruce plantations in the boreal zone may suffer height growth decreases of up-to 10% due to increased drought-stress. Vegetation control and mechanical site preparation treatments appear to mitigate effects of climate change to some extent. In the third part of the thesis I explored the combined effects of climate and trembling aspen competition on spruce and aspen growth using data from a long-term study in the boreal zone. Results indicate that climate variables and initial size of the tree can account for significant portions of the annual growth of spruce. Including an estimate of aspen competition in the equations improved the predictive ability of these models. Evidence of the inter-annual variability in aspen competitiveness on spruce and aspen growth indicates that the stress-gradient hypothesis can be applied in boreal mixedwood forests. / Forest Biology and Management

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniversitet, 2009. / Härtill 5 uppsatser.

No description available.

The exotic Pinus plantations of southeast Queensland occupy approximately 130 000 ha and are prominent in catchments which drain to estuarine and marine waters that are economically, socially, and environmentally important. Recently, the deterioration of estuarine and marine water quality has raised concerns about the possible off-site impacts from the intensive management of the Pinus estate in southeast Queensland. Additionally, forest managers have raised questions over the effects of the currently adopted management practices on soil, water, and nutrient resources within plantations. A paucity of information regarding the impacts of these plantations in the humid sub-tropics of southeast Queensland initiated the research presented here. The objectives of this study were to: (i) determine the influence specific Pinus management techniques (harvesting, site-preparation, prescribed burning and forest roads) have on runoff generation; (ii) quantify fluxes of some nutrients (nitrogen (N), phosphorus (P), dissolved organic carbon (DOC) and iron (Fe)) and suspended solids (SS) in runoff from these management treatments; and, (iii) assess the overall effectiveness of the currently adopted Best Management Practices (BMP's) in protecting on-site soil, water and nutrient resources, as well as protecting off-site waters from pollution. The study site was located in an intensively managed sub-catchment within the Beerburrum State Forest Pinus plantation on the coastal plain of the Pumicestone region, southeast Queensland. This study was established in October 2001 and consisted of a 141 ha catchment based investigation into water quality and hydrology, which received a 50 ha harvest treatment in February and March 2002. Water was monitored for two water years (October 2001 - September 2003), and incorporated site-preparation and the establishment of the subsequent rotation. The influence of a forest road stream crossing was also monitored in this component of the investigation. Two discrete forest road plots were monitored for the same period to measure the response of runoff, nutrient and sediment fluxes to different road surface materials (gravelled and ungravelled), road maintenance and traffic intensity. Rainfall simulation was used on small plots covering specific management treatments (clearfall harvest, cultivation, fertilised cultivation, prescribed fire and established trees) within the general plantation area to determine their influence on water, sediment and nutrient fluxes. The investigation in the catchment receiving inter-rotation management revealed that that there was very little difference in water quality indices up and downstream of the forest road stream crossing, which suggests that road borne runoff contributed only minor amounts of N, P, Fe and SS to the stream. Perched groundwater quality within the general plantation area was similar to that observed in the adjacent stream. Water quality monitoring within the Coochin-Mellum and Coonowrin Creek catchments showed that the mean annual concentrations of N and P in surface waters were highest from catchments hosting agriculture and residential areas, respectively. Mean annual DOC and Fe concentrations were highest from the catchment hosting native Wallum vegetation. The mean annual concentration of SS was highest from an unmanaged native forest catchment. The rainfall simulation on specific management treatments revealed that mean losses of N and P from unfertilised and unburnt treatments were comparable to loads reported from catchment scale studies in the Pinus plantations of south-east Queensland. Mean SS loads from all treatments were considerably higher than stream loads reported in the literature from catchment scale investigations, and suggest that the currently adopted mitigation practices between the general plantation area and streams are effective in promoting the deposition of entrained solids. The investigation into gravelled and ungravelled forest roads revealed that the mean runoff coefficient (runoff depth / rainfall depth) was consistently higher from the gravelled road plot with 0.57, as compared to the ungravelled road with 0.38. Total sediment loss over the two year period was greatest from the gravelled road plot. Suspended solids contributed 86% of the total sediment loss from the gravelled road and 72% from the ungravelled road over the two years. When road and drain maintenance (grading) was performed runoff and sediment loss was increased from both road types. It should be noted that the results presented herein were based on only two water years, and both years experienced below average rainfall. As such it is important that future research in a catchment prone to waterlogging be conducted over a longer term so as to increase the chance of quantifying water, nutrient and sediment fluxes in response to average and above average rainfall years. It is likely that in above average rainfall years the results for nutrient and sediment fluxes from the general plantation area would be significantly different as runoff would be more readily generated and sustained for longer periods. Overall, the research presented suggests that the management of an exotic Pinus plantation during the inter-rotation period results in relatively low fluxes of N, P, SS Fe and DOC in stream water and vindicates the use of the current practices in protecting on-site water, soil and nutrient resources.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

The research in this thesis concentrates on investigation of the ecology of Arundinaria species for restoration purposes. Arundinaria species are key components in the canebrake ecosystem that was once prominent in the southeastern United States. Arundinaria still occurs as an understory component of bottomland hardwood forests, but with intense agricultural development and urbanization over the past 200 years, canebrakes are now a critically endangered ecosystem with greater than 98% loss. Specifically the thesis addresses the establishment of Arundinaria with other plant species and site preparation techniques. This study indicated that A. gigantea planted into plots dominated by non-native plants benefited significantly more from site preparation (soil tillage, herbicide application) than cane planted into native-species-dominated assemblages. The last portion of the research examined effects of inundation on A. gigantea and A. tecta. Arundinaria tecta appeared to be more flood tolerant than A. gigantea, reflecting habitats in which these species are known to occur.

Intensively managed forests of the Southern United States are among the most important sources of wood fiber and timber in this country. There is a great deal of concern that disturbances associated with trafficking by heavy machinery might diminish long-term soil-site productivity. However, determining the effect of harvesting disturbance and silvicultural treatments on the long-term productivity of pine plantations is difficult because, in addition to harvesting effects, growth distributions are affected by changes in climate, silviculture, and genetics. The primary objectives of this study were to determine (1) whether logging disturbances under operationally realistic circumstances affect soil quality, hydrologic function, and loblolly pine (Pinus taeda L.) productivity on wet pine flats, and (2) whether intensive forest management practices mitigate disturbance effects if they exist. Three 20-ha loblolly pine plantations located on wet pine flats in South Carolina were subjected to combinations of wet- and dry-weather harvesting and mechanical site preparations. Changes in soil-site productivity after five years were evaluated using a new rank method. The key advantage of the rank change method is that it is largely independent of the confounding factors (e.g. genetics, silvicultural practices, and climate) that affect comparisons of tree growth and soil quality between growth cycles. After five years, loblolly pine site indexes (base age 25) ranged between 13 and 33 m, and production ranged between 0.5 and 95 Mg ha-1. Soil bulk densities increased from 1.15 to as high as 1.44 g cm-3 after harvesting; by age 7 years it had decreased to approximately 1.25 g cm-3. At the sub-stand scale (0.008 ha), visually assessed soil physical and harvesting residue disturbances had little influence on relative changes in soil-site productivity after five years. Factors that specifically reflect site drainage were the most influential on changes in productivity. At the operational scale (3.3 ha), there were no differences between wet- and dry- harvested sites as long as bedding was applied as a site treatment. These results indicate that when standard site preparation is employed, fertile, wet pine flats such as these are resilient in that they recover from severe, but operationally realistic, harvesting disturbances. / Ph. D.

Over one million hectares of pocosins and wet flats in the southeastern coastal plain are intensively managed for the production of loblolly pine (Pinus taeda) plantations. These management activities may have adverse effects on soil physical properties, site hydrology, and overall site productivity. Substantial quantities of wood residues are often left on these sites by timber harvesting operations, and it was hypothesized that the incorporation of this slash into the soil could improve the soil physical properties and site hydrology. One organic pocosin site and one mineral wet flat site were chosen post-harvest for treatment. The wet flat study was organized as an incomplete block design having four blocks and six treatments: (i) conventional bedding, (ii) strip surface mulching with bedding, (iii) strip surface mulching with tillage and bedding, (iv) broadcast mulch without bedding, (v) broadcast mulch with bedding, and (vi) flat planted control. The pocosin study was organized as a randomized complete block design with four blocks and four treatments. The treatments are identical to those of the wet flat site without the broadcast mulch treatments (iv and v). Soil physical property data was analyzed pre- and post-treatment, while post-treatment site hydrology and soil water chemistry data was analyzed periodically for one year. Seedling survival and height data were analyzed after one growing season. The treatments had little effect on soil physical properties, site hydrology, soil water nutrients, or seedling survival on the wet flat study site. Bedding in general significantly increased tree height growth, but mulching had no significant effects. The treatments had little effect on soil physical properties on the pocosin study site except for soil macroporosity, which was significantly increased by bedding. Site hydrology and soil water nutrients were not significantly affected by the treatments, but seedling survival and height growth were significantly increased by bedding. Mulching had no significant effects on any of the parameters studied. / Master of Science