Effects of Season of Burning on the Microenvironment of Fescue Prairie in Central Saskatchewan

The microenvironmental effects of spring, summer and autumn burns were investigated for a small area of fescue prairie in Saskatchewan over two growing seasons. Maximum fire temperature in all burns exceeded 300°C at a height of 5-10 cm in the canopy. At a depth of 1 cm in the soil, temperature increased to 40°C during the summer burn, but was unaffected by burns at other seasons. Spring-burned grasses recovered to the same height as the unburned control plot by the end of the first summer. Grass height was similar in all plots by the end of the second growing season, but aboveground biomass in all burned plots was about half that of the control. Graminoid leaf area index at the end of the second growing season ranged from 0.65 in the control plot to 0.27 in the autumn burn. Surface albedos dropped to about 0.03 immediately after burning and took about 3 months to return to the pre-burn values near 0.20. By mid-June of the second year, albedos were similar in all plots. Soil temperatures at 50 cm depth in the burned plots were higher than in the control during the first summer and lower during the winter. The greatest winter snowpack (73 mm water equivalent) accumulated in the control, compared to 48, 35 and 25 mm in the spring, summer and autumn burned plots, respectively. In the first growing season the greatest demand for water occurred in the spring plot followed by the summer, control and autumn plots. In the second season water demand did not differ significantly among plots, reflecting the similarities in plant cover. The microenvironmental effects of a single burning episode in fescue prairie disappear rather quickly, so that there is little long-term impact on the vegetation

Underground railroads: citizen entitlements and unauthorized mobility in the antebellum period and today

In recent years, some scholars and prominent political figures have advocated the deepening of North American integration on roughly the European Union model, including the creation of new political institutions and the free movement of workers across borders. The construction of such a North American Union, if it included even a very thin trans-state citizenship regime, could represent the most significant expansion of individual entitlements in the region since citizenship was extended to former slaves in the United States. With such a possibility as its starting point, this article explores some striking parallels between the mass, legally prohibited movement across boundaries by fugitive slaves in the pre-Civil War period, and that by current unauthorized migrants to the United States. Both were, or are, met on their journeys by historically parallel groups of would-be helpers and hinderers. Their unauthorized movements in both periods serve as important signals of incomplete entitlements or institutional protections. Most crucially, moral arguments for extending fuller entitlements to both groups are shown here to be less distinct than may be prima facie evident, reinforcing the case for expanding and deepening the regional membership regime

Demographic and Genetic Patterns of Variation among Populations of Arabidopsis thaliana from Contrasting Native Environments

Background: Understanding the relationship between environment and genetics requires the integration of knowledge on the demographic behavior of natural populations. However, the demographic performance and genetic composition of Arabidopsis thaliana populations in the species' native environments remain largely uncharacterized. This information, in combination with the advances on the study of gene function, will improve our understanding on the genetic mechanisms underlying adaptive evolution in A. thaliana. Methodology/Principal Findings: We report the extent of environmental, demographic, and genetic variation among 10 A. thaliana populations from Mediterranean (coastal) and Pyrenean (montane) native environments in northeast Spain. Geographic, climatic, landscape, and soil data were compared. Demographic traits, including the dynamics of the soil seed bank and the attributes of aboveground individuals followed over a complete season, were also analyzed. Genetic data based on genome-wide SNP markers were used to describe genetic diversity, differentiation, and structure. Coastal and montane populations significantly differed in terms of environmental, demographic, and genetic characteristics. Montane populations, at higher altitude and farther from the sea, are exposed to colder winters and prolonged spring moisture compared to coastal populations. Montane populations showed stronger secondary seed dormancy, higher seedling/juvenile mortality in winter, and initiated flowering later than coastal populations. Montane and coastal regions were genetically differentiated, montane populations bearing lower genetic diversity than coastal ones. No significant isolation-by-distance pattern and no shared multilocus genotypes among populations were detected. Conclusions/Significance: Between-region variation in climatic patterns can account for differences in demographic traits, such as secondary seed dormancy, plant mortality, and recruitment, between coastal and montane A. thaliana populations. In addition, differences in plant mortality can partly account for differences in the genetic composition of coastal and montane populations. This study shows how the interplay between variation in environmental, demographic, and genetic parameters may operate in natural A. thaliana populations. © 2009 Montesinos et al

Review of \u3ci\u3e Terrestrial Ecoregions of North America: A Conservation Assessment\u3c/i\u3e by Taylor H. Ricketts and Eric Dinerstein

Terrestrial Ecoregions of North America provides a comprehensive assessment of the status of biodiversity and conservation within the United States and Canada. Part of a global program conducted by the World Wildlife Fund, it is essentially a reference work offering baseline data for conservation planning and restoration. The book emphasises the precarious condition of many natural areas in North America, at the same time illustrating the great diversity that still exists in some areas and stressing the sense of urgency required to ensure the preservation of viable plant and animal populations in their natural habitats. It is not a textbook on conservation, however, but an evaluative report based on carefully described methodology and summary analysis that integrates an index of biological distinctiveness and an index of conservation status for 116 ecoregions. Ecoregions are defined as relatively large areas of land or water that contain geographically distinct assemblages of natural communities. As part of this assessment, ecoregion maps were compared with the ranges of over 20,000 North American species of native vascular plants, birds, butterflies, mammals, reptiles, amphibians, and terrestrial molluscs. Other procedures, equally comprehensive, considered information collected in other studies and assessments by expert committees

Seed input as a factor in the regeneration of strip-mine wastes in Saskatchewan

Seed traps were set out on the spoil banks created by strip-mine coal operations in southeastern Saskatchewan. A total of 2721 seeds (2387 seeds/m2) was collected in the 1st season of which 97% was comprised of forb seeds and 3% of grass caryopses; 4216 seeds (3798 seeds/m2) were trapped in the 2nd year. Kochia scoparia was the most abundant species. Adequate seed input is occurring in the area to provide a good vegetation cover. The general absence of vegetation on the wastes must therefore reflect subsequent removal and deterioration of the seeds. </jats:p

Straw residues in wild rice (<i>Zizania palustris</i> L.) stands in northern Saskatchewan

Straw production in wild rice stands fluctuates markedly from year to year. In the short term, heavy straw accumulation may reduce grain yields by smothering seedlings; in the long term, the balance of nutrients in a lake may be affected. An aquatic weed harvester was used to remove standing straw from part of a wild rice stand at the end of the growing season. Compared to the control plot, grain production increased twofold in the following year. However, straw production also increased significantly and may exacerbate the problem in future years. Decomposition bags containing chopped and unchopped straw were submerged in a lake to assess the rate of straw breakdown: complete decomposition may require 3 yr. Decomposition occurred most rapidly during the early part of each growing season. No difference was noted in rates of decomposition or nutrient release between the chopped and unchopped straw. Reduced light levels under straw loadings up to 5000 kg ha−1 in laboratory trials did not affect seedling development. However, seedling survival was severely reduced under artificial straw loads and none survived straw additions equivalent to 5000 kg ha−1. Key words: Wild rice, Zizania palustris, Saskatchewan, straw production, nutrient content, decomposition rates </jats:p

Seed input into a postfire forest site in northern Saskatchewan

Seed traps were installed at seven sites along a transect in a burned mixedwood forest site in northern Saskatchewan to determine annual seed inputs. The seeds were returned to the laboratory for germination and identification. A total of 1698 seeds was collected in the 1977–1978 season, representing a seeding rate of 8.98 million seeds/ha. Epilobiumangustifolium L. was most abundant representing 63% of the total. Betulapapyrifera Marsh, accounted for 27.6% and Piceaglauca (Moench) Voss 6.1%. The seed count for 1978–1979 was 651 (3.44 million/ha) and represented a significant decline in herb and tree seeds. </jats:p

Wild rice - a potential new crop for Finland

Wild rice (Zizania palustris L.), an aquatic grass that grows naturally in lakes and slowly flowing rivers in North America, has been used as a food for thousands of years by some aboriginal tribes. In natural stands, the seeds mature in the autumn and overwinter on the lake bed. They germinate in May, with growth to maturity requiring approximately 100 days. The similarity of growing conditions between North America and Finland suggests that wild rice might succeed in northern Europe. The wild rice plant and the production of both organically grown Canadian wild rice and paddy-grown wild rice in the USA are briefly described in this review article together with the results of preliminary growth trials and an assessment of its agricultural role in Finland.Villiriisi on Pohjois-Amerikassa kasvava yksivuotinen heinäkasvi. Se viihtyy järvissä ja hitaasti virtaavissa joissa. Intiaanit ovat käyttäneet villiriisiä viljojen tapaan ravinnoksi vuosituhansien ajan. Villiriisi kylvetään syksyllä, jolloin se alkaa itää toukokuun alussa itämislevon murruttua. Tuleentuakseen se tarvitsee noin 100 vuorokautta itämisestä. Kasvustoja ei tarvitse ensimmäisen vuoden jälkeen kylvää uudelleen, koska osa siemenistä varisee heti tuleennuttuaan,mikä toisaalta tekee villiriisin korjuusta hankalaa. Satoa korjataan yleensä neljästä seitsemään kertaan syksyllä erityisrakenteisella veneellä (hydrokopteri). Minnesotassa jalostettujen villiriisilajikkeiden sadonkorjuu voidaan kuitenkin tehdä kerralla hieman normaalista muunnellulla leikkuupuimurilla kuivatulla maalla. Kanadalainen villiriisi on hinnaltaan hieman USA:ssa tuotettua kalliimpaa johtuen mm. siitä, että Kanadassa villiriisi tuotetaan luonnontilaisissa joissa ja järvissä ja kasvinsuojeluaineiden ja lannoitteiden käyttö on kiellettyä. Villiriisi on tähän asti ollut lähinnä hinnakas herkku, jota on käytetty erityisesti riistaruokien lisukkeena. Nykyisin, hintojen laskettua, villiriisiä on alettu käyttää jokapäiväisenä ruokana perunan, riisin ja pastan korvikkeena tai osana pataruokia ym. Uusien tutkimusten perusteella villiriisin käyttö erilaisiin valmisruokateollisuuden sovellutuksiin, kuten jauhelihapihveihin ja makkaroihin, parantaa näiden laatua huomattavasti. Koska villiriisin kysyntä maailmalla on ollut jatkuvassa kasvussa ja sen tuottajahinta on melko korkea, voidaan villiriisin viljelyn Suomessa olettaa muodostuvan taloudellisesti kannattavaksi. Villiriisi on menestynyt Suomessa erinomaisesti järjestämissämme esikokeissa ja tuottanut satoa sekä lisääntynyt. Tulevaisuudessa olisi kuitenkin tarkemmin selvitettävä villiriisin kasvupaikkaedellytykset ja siihen liittyvät tekijät sekä sadonmuodostus Suomen oloissa, jotta mahdollinen kaupallinen tuotanto saataisiin hyvälle pohjalle. Tutkimustemme eräänä lähtökohtana on ollut villiriisin ekologinen tuotanto ilman kasvinsuojeluaineita ja lannoitteita kanadalaisen mallin mukaisesti. Perusedellytykset villiriisin tuotantoon Suomessa ovat hyvät, sillä vesistöissä on riittävästi ravinteita, erityisesti fosforia ja typpeä. Villiriisi saattaisikin olla hyvä vesistöihin huuhtoutuneen typen ja fosforin sitoja, estäen järvien rehevöitymistä tai mahdollisesti vähentäen jo rehevöityneiden järvien ravinnepitoisuuksia, erityisesti mikäli myös korret poistettaisiin vesistöistä. Lisäksi mm. vanhoja, käytöstä poistettuja turvesoita ja muita vastaavia vesijättöalueita olisi mahdollista hyödyntää villiriisin tuotantoalueina, jolloin alueet olisivat kauniita maisemallisesti ja toimisivat kosteikkoalueina monille linnuille ja nisäkkäille