Germination Biology and the Ecology of Annual Plants

We derive spatially explicit population models for the interaction between a species of annual plant and a community of perennial species. The models are used to explore the conditions for persistence of the annual in both a constant and a stochastic environment. In both types of environment a seed's response to the presence of established perennial plants is found to affect strongly the conditions for persistence. Sensitivity analysis of a parameterized version of the model indicates the importance of germination and mortality parameters in allowing persistence. In the parameterized model large changes in fecundity have little effect on the condition for persistence. The implications of these results for the distribution of annual plants and the forces structuring communities of short-lived plants in successional habitats are discussed

Soil Compaction Effects on Root-Zone Hydrology and Vegetation in Boreal Forest Clearcuts

Soil compaction is a common consequence of forestry traffic traversing unprotected, moist soils; it decreases porosity and affects hydraulic conductivity even in coarse-textured soils. The aim here was to study root-zone hydrology and vegetation in three microsites (in, between, and beside wheel tracks) 4 to 5 yr after forwarder traffic, on stony and sandy till soils in two clearcuts in northern Sweden. Measurements of soil volumetric water content (VWC), vegetation indicators and one-dimensional hydrological modeling (Hydrus-1D) of wheel tracks and undisturbed soil were conducted. Soil VWC was monitored hourly during 2017 and 2018 in three or four plots along a slope on each site. Soil VWC was also measured once with a portable sensor in 117 plots along two slopes at each site, where the vegetation was recorded and analyzed using Ellenberg indicator indexes. Soil VWC was highest in wheel tracks and lowest between tracks; this was corroborated by the species composition in the wheel tracks (Ellenberg indicator for soil moisture). Bare soil was more frequent in wheel tracks and between tracks than in undisturbed soil. The model simulations indicated that the changed soil hydraulic properties influenced the VWC results in the wheel tracks. However, the differences in average pressure heads in the root zone were small between the microsites and only apparent during dry periods. In the wheel tracks, air-filled porosity was <0.10 m3 m-3, indicating insufficient soil aeration during 82% (Site T) and 23% (Site R) of the 2017 growing season. Insufficient aeration could be one explanation for the presence of some still unvegetated areas

Niches, rather than neutrality, structure a grassland pioneer guild

Pioneer species are fast-growing, short-lived gap exploiters. They are prime candidates for neutral dynamics because they contain ecologically similar species whose low adult density is likely to cause widespread recruitment limitation, which slows competitive dynamics. However, many pioneer guilds appear to be differentiated according to seed size. In this paper, we compare predictions from a neutral model of community structure with three niche-based models in which trade-offs involving seed size form the basis of niche differentiation. We test these predictions using sowing experiments with a guild of seven pioneer species from chalk grassland. We find strong evidence for niche structure based on seed size: specifically large-seeded species produce fewer seeds but have a greater chance of establishing on a per-seed basis. Their advantage in establishment arises because there are more microsites suitable for their germination and early establishment and not directly through competition with other seedlings. In fact, seedling densities of all species were equally suppressed by the addition of competitors' seeds. By the adult stage, despite using very high sowing densities, there were no detectable effects of interspecific competition on any species. The lack of interspecific effects indicates that niche differentiation, rather than neutrality, prevails

Evaluation of coated urea for ammonia volatilization loss, nitrogen mineralization and microsite pH in selected soil series

The increase in microsite soil pH due to surface application of urea to the soil is an important reason of ammonia volatilization loss and fast hydrolysis process. The use of Cu and Zn with biodegradable materials coatings were assumed to reduce ammonia volatilization losses by reducing soil pH and slowing down hydrolysis process. The present study was conducted to evaluate the effects of coated urea with the combination coatings of Cu, Zn, palm stearin, agar and gelatine on microsite pH. For this purpose, six urea treatments named; uncoated urea or control, Cu and palm stearin coated urea, Cu and agar coated urea, Cu and gelatine coated urea, Cu coated urea, Cu and Zn coated urea were prepared and evaluated for their effects on microsite pH, ammonia volatilization loss and mineralization of N in three tropical soil. For the each soil; soil properties, soil microsite pH, ammonia volatilization loss and N mineralization were determined with slandered methods. The results reveal that the microsite pH in the three soils varied significantly due to the variability in texture. The pH of microsite treated with coated urea was lower than the uncoated urea treatments in each soil. The reduction in the microsite soil pH was associated with urea hydrolysis. The rate of mineralization (30%) and ammonia volatilization (50%) reduced in the soils where the pH was low or stable on the fertilizer microsite after adding the fertilizer treatments. The results of this study proved the positive effectiveness of coating material and potential to control fast hydrolysis process and ammonia volatilization losses

Observations of \u3ci\u3eIncisalia Irus\u3c/i\u3e (Lepidoptera: Lycaenidael in Central Wisconsin 1988-95

In surveys conducted during 1988-95, 164 individuals of the frosted elfin (Incisalia irus) were found, 139 of them during formal transects that totaled 92.9 hr and 179.4 km of survey effort during the frosted elfin flight period. Individuals were observed between 10 May and 14 June, with maximum . t spans in a single year of 27-31 days. Peak flight occurred just before or e beginning of peak flowering of the larval host, wild lupine (Lupinus perennis), and the first spring adults of Karner blue (Lycaeides melissa samuelis), also monophagous as larvae on wild lupine. Fourteen individuals exhibited oviposition behavior on young stalks of green lupine flower buds. 94% of individuals occurred in savannas, nearly evenly split between open (10-24% canopy) and closed (25-49% canopy) ones. Relative lupine abundance at both the microsite and landscape scales appeared more important as a habitat factor than actual size of the particular lupine patch occupied. Both long-term lack of site management and too frequent/intense management (forestry, rotational fire) appeared unfavorable. Recreational trailsides, areas burned by wildfire \u3e4 years ago, and rights-of-way mowed annually or less often were favorable habitat. All frosted elfin sites also supported Karner blues, but within these sites, correlation of frosted elfin abundance with that of Karner blues was rather weak, indicating a fair degree of niche segregation between these two species

The digitization of music and the accessibility of the artist

©Journal of Professional Communication, ISSN: 1920-685. All rights reservedThis article uses case studies to explore two ways in which technology can impact on artist production. First, technological innovations could facilitate many things that are not new by rather making existing processes better or cheaper in ways that might alter the situation meaningfully. Second, technology can change art through the more profound revision of the role of artist and art-perceiver (Fineberg, 2006). This article examines several examples of how the music industry has been impacted by new technology: Radiohead Rainbows, slicethepie.com, Ditto Music, Music Rainbow, YouTube Orchestra, micro-chunking and LiveFi. The article examines the impact of new technologies on classical music.Peer reviewe

Dispersal and establishment both limit colonization during primary succession on a glacier foreland

Plant colonization can be limited by lack of seeds or by factors that reduce establishment. The role of seed limitation in community assembly is being increasingly recognized, but in early primary succession, establishment failure is still considered more important. We studied the factors limiting colonization on the foreland of Coleman Glacier, Washington, USA to determine the importance of seed and establishment limitation during primary succession. We also evaluated the effects of seed predation, drought and existing vegetation on establishment. We planted seeds of seven species into plots of four different ages and found evidence that both seed and establishment limitation are strong in early succession. We also found that seed and establishment limitation both remained high in later stages of succession. Seed predation reduced establishment for most species and some evidence suggested that drought and existing vegetation also limit establishment. Because both dispersal and establishment failure restrict colonization in recently exposed habitat, late-seral forest species may have a difficult time migrating upward in response to global climate change

Links between soil microbial communities and plant traits in a species-rich grassland under long-term climate change

Climate change can influence soil microorganisms directly by altering their growth and activity but also indirectly via effects on the vegetation, which modifies the availability of resources. Direct impacts of climate change on soil microorganisms can occur rapidly, whereas indirect effects mediated by shifts in plant community composition are not immediately apparent and likely to increase over time. We used molecular fingerprinting of bacterial and fungal communities in the soil to investigate the effects of 17 years of temperature and rainfall manipulations in a species‐rich grassland near Buxton, UK. We compared shifts in microbial community structure to changes in plant species composition and key plant traits across 78 microsites within plots subjected to winter heating, rainfall supplementation, or summer drought. We observed marked shifts in soil fungal and bacterial community structure in response to chronic summer drought. Importantly, although dominant microbial taxa were largely unaffected by drought, there were substantial changes in the abundances of subordinate fungal and bacterial taxa. In contrast to short‐term studies that report high resistance of soil fungi to drought, we observed substantial losses of fungal taxa in the summer drought treatments. There was moderate concordance between soil microbial communities and plant species composition within microsites. Vector fitting of community‐weighted mean plant traits to ordinations of soil bacterial and fungal communities showed that shifts in soil microbial community structure were related to plant traits representing the quality of resources available to soil microorganisms: the construction cost of leaf material, foliar carbon‐to‐nitrogen ratios, and leaf dry matter content. Thus, our study provides evidence that climate change could affect soil microbial communities indirectly via changes in plant inputs and highlights the importance of considering long‐term climate change effects, especially in nutrient‐poor systems with slow‐growing vegetation