Plant Sciences Commons^™

Yponomeuta Evonymellus Outbreaks In Southern Finland: Spatial Synchrony But Different Local Magnitudes, Brian J. Wilsey, Conchita Alonso, Timo Vuorisalo, Tuija Honkanen

Brian J. Wilsey

Defoliations of Prunus padus by Yponomeuta evonymellus were monitored in two areas in southern Finland. During a long-term study (1980–1995) in the area with high peak defoliations, P. padus trees recorded two defoliation peaks, leading to complete defoliation of many trees. The negative relationship between pupal mass and current year tree defoliation during the peak years suggested shortage of food affected reproductive potential of Y. evonymellus. Furthermore, no delayed induced resistance was observed in these populations. Interannual correlations in degrees of defoliation experienced by individual trees were low, i.e. high defoliation in one year did not predict the degree of …

Die Mechanik "Weicher" Pflanzlicher Gewebe [The Mechanics Of 'Soft' Plant Tissues], Winfried S. Peters

Winfried S. Peters

The Mechanic State Of “Inner Tissue” In The Growing Zone Of Sunflower Hypocotyls And The Regulation Of Its Growth Rate Following Excision, Winfried Peters, A. Tomos

Winfried S. Peters

Effects Of Synchrony With Host Plant On Population Of A Spring-Feeding Lepidopteran, Joseph Elkinton, A. F. Hunter

Joseph Elkinton

Comparisons of traits of outbreaking and nonoutbreaking leaf-eating Lepidoptera and Symphyta have shown that spring-feeding species are more likely to have outbreaks than are summer-feeding species. It has been suggested that variable synchrony with host budburst causes the population sizes of spring-feeding species to be more variable primarily because of the negative effects of older leaves on insects. While much evidence exists that leaf age can directly affect survival and reproduction of insects, few studies have looked at the population-level effects of variable phenology, and especially the potential for complex direct and indirect interactions with natural-enemy effects. To examine the …

What Makes Plants Different? Principles Of Extracellular Matrix Function In 'Soft' Plant Tissues [Review Article], Winfried Peters, Wolfgang Hagemann, A. Tomos

Winfried S. Peters

Additive And Nonadditive Effects Of Herbivory And Competition On Tree Seedling Mortality, Growth, And Allocation, Scott J. Meiners, Steven N. Handel

Scott J. Meiners

The interaction between simulated cotyledon herbivory and interspecific competition was studied in a greenhouse experiment using two species of trees, Acer rubrum and Quercus palustris, which commonly invade abandoned agricultural fields. Herbivory treatments were applied as a gradient of cotyledon removal for A. rubrum with 0, 25, 50, 75, and 100% of cotyledon tissue removed. Cotyledons from Q. palustris were clipped and removed (control, early, and late removal) to create a gradient of seed reserve availability. The competition treatment consisted of plugs of old-field vegetation that filled the pots with perennial cover. Mortality of seedlings was higher with competition. There …

Season And Distance From Forest - Old Field Edge Affect Seed Predation By White-Footed Mice, Scott J. Meiners, James T. Mccormick

Scott J. Meiners

We studied the spatial pattern of seed predation across a forest-old field edge in both fall and winter to assess the potential for seed predators to influence plant spatial patterns. We used a 100 x 100 m grid that began 30 m inside the forest and extended 60 m into the old field. Inside this grid we placed seed stations at regular 10 m intervals and monitored seed removal. Seed predation varied significantly across the edge gradient in both fall and winter with the highest rate of seed removal at the edge in both trials. The spatial pattern of seed …

Container Substrate Temperatures Affect Mineralization Of Composts, Helen T. Kraus, Robert Mikkelsen, Stuart L. Warren

Robert Mikkelsen

Traditional N mineralization studies have been conducted by soil scientists using soils and temperatures found in field production. As temperature, in part, governs the rate of mineralization, and container substrates reach much higher temperatures than do soils, the effect of these elevated temperatures on mineralization must be considered to begin to understand N mineralization in container substrates during production. The N mineralization patterns of three composts [turkey (Meleagris gallopavo) litter, yard waste, and municipal waste] were determined under three temperature regimes (45, 25, and 45/25 °C). More organic N was mineralized from composted turkey litter (CTL) than from municipal or …

Beneficial Use Of Swine By-Products: Opportunities For The Future, Robert Mikkelsen

Robert Mikkelsen

No abstract provided.

Toward An Ecosystem Approach To Remediation In The Great Basin, Ted K. Raab

Ted K. Raab

We consider the web of interactions among geologic materials, soils, plants, and animals to ask, "If mining or other extractive energy technologies occur in desert regions, what do we need to know to return the land to productivity?" The Great Basin represents a formidable challenge in this regard, as winters in these cold deserts and seasonal lack of moisture during parts of the year severely constrain the growing season for vegetation. Due to the nature of current or proposed mining activities in this region, we have chosen to concentrate on two potential pollutants: the trace element selenium (Se) and nitrate …

Biodiversity And Ecosystem Functioning: Importance Of Species Evenness In An Old Field, Brian J. Wilsey, Catherine Potvin

Brian J. Wilsey

Changes in land use, habitat fragmentation, nutrient enrichment, and environmental stress often lead to reduced plant diversity in ecosystems. However, it remains controversial whether these reductions in diversity will affect energy flow and nutrient cycling. Diversity has two components: species richness, or the number of plant species in a given area, and species evenness, or how well distributed abundance or biomass is among species within a community. We experimentally varied species evenness and the identity of the dominant plant species in an old field of Quebec to test whether plant productivity would increase with increasing levels of evenness, and whether …

Performance Of Trees In The Massachusetts Planting Of The 1994 Nc-140 Peach Rootstock Trial Over Seven Growing Seasons, Wesley Autio, James Krupa, Jon Clement

Wesley Autio

No abstract provided.

Performance Of Trees In The Massachusetts Planting Of The 1994 Nc‐140 Apple Rootstock Trial Over Seven Growing Seasons, Wesley Autio, James Krupa, Jon Clement

Wesley Autio

No abstract provided.