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

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

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

Microclimate of an Aboriginal Winter Campsite at Wanuskewin Heritage Park, Saskatoom

The microclimate of an aboriginal winter campsite, set in an incised, south-facing meander of a small creek, is compared to the conditions on the adjacent open prairie at Wanuskewin Heritage Park, Saskatoon, Saskatchewan. Maximum and minimum temperatures and wind speeds were measured daily, on the prairie and in the valley, along with temperatures in a modern canvas tipi erected in the valley. Maximum temperatures tended to be about 1 °C higher in the valley, and 2 °C higher in the tipi, than on the prairie, while minima were 1-2 °C lower. Wind speeds were reduced to about 50% in the valley. Windchill factors, derived from these data, were reduced between 200 and 250 W m-2 , suggesting that the valley site afforded considerable benefit as a winter habitation site

Seed bank dynamics in tall-tussock grasslands along an altitudinal gradient

We studied the germinable soil seed bank of tall-tussock grasslands along an altitudinal gradient in the mountains of central Argentina. We selected 10 sampling plots at three altitudinal levels (1200 m, 1600 m and 2200 m). We assessed the composition of the established vegetation and took ten compound soil samples (0-5 cm depth) at each plot in autumn and spring. The soil samples were sieved, chilled, and incubated in a glasshouse to assess the composition of the seed bank. The similarity between the composition of the seed bank flora and that of the established vegetation was low throughout the gradient. Most species did not change their seed bank strategy along the gradient. Seed bank richness and density increased with altitude. Most species had a persistent seed bank at all altitudinal levels, and the proportion of such species increased with altitude. These results suggest that a cold climate directly and/or indirectly favours the formation of seed banks and seed persistence in the soil.Fil: Funes, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Basconcelo, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Cabido, Marcelo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin