Reclamation of a limestone quarry to a natural plant community in the Rocky Mountains of southern Alberta

Reclamation of limestone quarries around the world is challenged by an extremely limiting environment, including steep slopes, scarce topsoil and high calcium carbonate substrates with low nutrients and water holding capacity. These issues were addressed at a limestone quarry in the Rocky Mountains of southern Alberta. Reintroduction of key components, such as vegetation and ameliorated soil were expected to speed recovery of ecosystem function. Season of seeding and soil amendment with manure mix, wood shavings and erosion control blankets were evaluated over two growing seasons to determine their effect on soil properties and native grass establishment. Season (fall, spring) of soil amending and seeding did not significantly affect revegetation or soil properties. Site characteristics such as slope, aspect, initial soil nutrients and surrounding plant communities influenced early plant community development and overall effects of soil treatments. Erosion control blankets resulted in highest seeded plant cover and lowest nonseeded plant cover despite not significantly changing soil chemical properties. Manure mix increased plant establishment, soil nutrients, microbial biomass and viable fungi and bacteria. Reclamation is postulated to be best with erosion control blankets and organic soil amendments like manure mix. Results from this work can be extrapolated to other limestone quarries or similar disturbances.Non UBCUnreviewedOthe

Grass utilization and grazing distribution within intensively managed fields in central Alberta

Grazing distribution and grass utilization was evaluated in intensively managed fields in the southern Aspen Parkland near Kirriemuir, Alberta. Three fields, 130 ha in size(with dimensions .4 x 3.2 km) were grazed by 1,000 cow/calf pairs for S days each. Stock water was accessible only from one end of each field. Grazing distribution was evaluated by monitoring grass utiliza- tion daily during grazing and after grazing at 0.1, 0.8, 1.6, 2.4, and 3.1 km from water. Final utilization did not differ within fields, escept for a decline at the maximum distance from water (3.1 km). Temporal utilization patterns existedand could best be described as a wave, with defoliation beginning near the water source on day 1 of grazing and proceeding outward from water until the ends of the fields were grazed on day 5. Final utilization was uniform; selective grazing of areas close to water was not removed by intensive management, but was masked by a rapid rate of defoliation

Ecological restoration for future sustainability in a changing environment

Since its emergence in the past decades, restoration ecology has demonstrated an astounding growth as a new discipline of applied science. At the same time, this young discipline has been criticized for its retrospective goals largely based on the past, its fragmented approach, and its idealistic goals, which do not relate to the real world context. Restoration with past-focused, idealistic, and/or ad hoc goals may not work in the future because an ecosystem that is restored for the past environment is not likely to be sustainable in the changing environment of the future, simple recomposition of isolated and fragmented naturalistic patches is not likely to restore ecosystem functions, and unrealistic goals and work plans are not likely to gain public support. We advocate directing the principles and practice of ecological restoration to the future. Future-aimed restoration should acknowledge the changing and unpredictable environment of the future, assume the dynamic nature of ecological communities with multiple trajectories, and connect landscape elements for improving ecosystem functions and structures. In this paper, we discuss the predictability of restoration trajectories under changing environmental conditions, the application of ecological theories to restoration practice, the importance of interdisciplinary approaches and human interventions in ecosystem recovery, and the social context of ecological restoration

Soil bulk density and biomass partitioning of Brachiaria decumbens in a silvopastoral system Densidade do solo e partição de biomassa de Brachiaria decumbens em um sistema silvopastoril

Shade in silvopastoral systems improves the thermal comfort of animals, but it may also affect the pasture productivity and can contribute to soil compaction in the shaded areas due to the increase in the number of animals looking for comfort. The effect of grazing at various distances from tree rows (under the tree canopy, at 6 and at 12 m away from the trees) on the soil bulk density and on the aerial and root biomass of Brachiaria decumbens was evaluated in both the dry and the rainy seasons. The study was carried out on an Orthic Ferralsol in a randomized block design with two replications. Tree rows were composed of Eucalyptus grandis and Acacia mangium species, and the paddocks were submitted to a rotational stocking management, using Holstein (Bos taurus) × Zebu (Bos indicus) heifers. The shade intensity in the pasture decreased with an increasing distance from the tree row. Soil bulk density did not vary with the distance from the tree row, but varied seasonally, being greater in the rainy season (1.47 g cm-3) than in the dry season (1.28 g cm-3). Green forage and root mass, expressed as dry matter, were lower under the tree canopy and were greater in the rainy season. There were decreases of 22.3 and 41.4% in the aerial and root biomasses, respectively, in the tree rows. The greatest shoot/root ratio for B. decumbens under moderate and intensive shading indicates a modification in the forage biomass allocation pattern that favours the aerial development in detriment of the root system.<br>O sombreamento em sistemas silvipastoris concorre para o conforto térmico dos animais; no entanto pode afetar a produção do pasto e contribuir para a compactação do solo, pelo aumento da concentração de animais nas áreas sombreadas. Avaliou-se o efeito da distância do renque de árvores (sob a copa das árvores, 6 e 12 m de distancia das árvores) na densidade do solo e na biomassa aérea e de raízes de Brachiaria decumbens, nas épocas seca e chuvosa. O estudo foi conduzido num Latossolo Vermelho-Amarelo no delineamento em blocos casualizados, com duas repetições. A faixa de árvores foi composta pelas espécies Eucalyptus grandis e Acacia mangium, e os piquetes foram manejados com novilhas Holandês (Bos taurus) × Zebu (Bos indicus) , sob lotação rotativa. A intensidade de sombreamento foi decrescente com o distanciamento do renque de árvores. A densidade do solo não variou com a distância do renque de árvores, mas sim com a época do ano, tendo sido maior na época chuvosa (1,47 g dm-3) do que na seca (1,28 g dm-3). As massas secas de forragem verde e de raízes foram menores sob a copa das árvores e maiores na época chuvosa do que na seca. Na faixa arborizada houve reduções de 22,3 e 41,4% na biomassa aérea e de raízes, respectivamente. A maior relação parte aérea/raiz da B. decumbens à sombra expressa uma modificação no padrão de alocação de biomassa na forrageira, que prioriza a formação da parte aérea, em detrimento do sistema radicular