No abstract

No abstract

High carbohydrate reserves and consequently low shoot to root ratios appear to increase tolerance to herbivory, whereas clonal species recover faster than nonclonal species. The role played by carbohydrates reserves suggests that these species could benefit from slightly higher light conditions in areas subjected to high deer pressure.

Overharvesting has caused major population declines in North America in non-timber forest products species such as ginseng and wild leek. Sustainable exploitation could be achieved through forest farming. Density reduction following bulb harvest could improve yield in natural wild leek stands that reach growth-limiting densities. Limiting the harvest to leaves may also provide an alternative form of exploitation, but could slow growth by reducing both carbon and nutrient reserves depending on the timing and intensity of such harvest. Our objectives were to assess the effects of (1) planting density and post-harvest density reduction, and (2) the timing and intensity of leaf harvest on subsequent growth and reproduction of wild leek. Three experiments were established. Bulbs were planted at densities from 44 to 356 bulbs m-2 , covering the range surveyed in natural populations. Plots in dense populations were subjected to up to 40% bulb harvest. In cultivated plots, either half or all the leaves on each plant were harvested, from 15 to 25 days after complete unfolding. Plants growing in higher density plots exhibited slower growth and reproduction rates, but greater productivity per cultivated area. A similar effect, albeit marginal, was obtained following bulb harvests in natural populations. Harvesting leaves did not affect survival, but delaying the harvest and harvesting only half of the leaves favored subsequent plant growth. We recommend harvesting down to a fixed bulb density rather than harvesting a fixed percentage of bulbs, and harvesting leaves only as ways to ensure sustainable exploitation of leeks.

Bussie`res, J., Rochefort, L. and Lapointe, L. 2015. Cloudberry cultivation in cutover peatland: Improved growth on less decomposed peat. Can. J. Plant Sci. 95: 479Á489. Cloudberry cultivation is being seriously considered as a rehabilitation option for industrial peatlands after horticultural peat extraction has ceased. Besides increasing the ecological and economic values of these sites, cloudberry cultivation could improve fruit yield and facilitate fruit harvesting compared to picking in natural peatlands. Previous studies reported slow establishment that was tentatively associated with substrate characteristics. Field and greenhouse experiments were thus conducted to better characterize the impact of different peat substrates in combination with restoration techniques on the growth of male and female clones. Cloudberry grew much better in less-decomposed fibric peat (H1ÁH3) than in more-decomposed mesic peat. Restoring the moss layer of the former peat field would thus need to precede cloudberry planting by a few years, in order to plant the rhizomes in a newly formed fibric peat layer. Male clones produced larger leaves and more ramets per rhizome than female clones under common greenhouse conditions, which indicated that differences between sexes are most likely genetic rather than environmental. Furthermore, we found cloudberry clones may be very sensitive to aluminium toxicity. In conclusion, the degree of peat decomposition appears to be one of the key factors determining the success of cloudberry plantations.Key words: Cutover peatland, substrate, peatland restoration, berry production, Rubus chamaemorus, dioecious species Bussie`res, J., Rochefort, L. et Lapointe, L. 2015. Culture de la chicoute´en tourbie`re exploite´e: Croissance accrue sur tourbe moins de´compose´e. Can. J. Plant Sci. 95: 479Á489. La culture de la chicoute´est se´rieusement e´value´e comme une option de re´habilitation des tourbie`res apre`s re´colte de la tourbe a`des fins horticoles. Outre le gain en termes de valeur e´cologique et e´conomique de ces sites, la culture de la chicoute´pourrait augmenter le rendement en fruits et faciliter la re´colte des fruits par rapport a`la re´colte en tourbie`res naturelles. Des e´tudes ante´rieures ont montre´une croissance initiale lente qui a e´te´provisoirement attribue´e aux caracte´ristiques du substrat. Des expe´riences sur le terrain et en serres ont donc e´te´mises en place pour mieux caracte´riser l'effet de diffe´rents substrats combine´e aux techniques de restauration, sur la croissance des clones maˆles et femelles. La chicoute´a pre´sente´une meilleure croissance en tourbe fibrique moins de´compose´e (H1ÁH3) qu'en tourbe me´sique plus de´compose´e. La restauration devrait donc pre´ce´der la mise en culture de la chicoute´de quelques anne´es, afin de planter les rhizomes dans la couche de tourbe fibrique nouvellement accumule´e. Les clones maˆles produisent des feuilles plus grandes et plus de ramets par rhizome que les clones femelles en conditions communes de croissance. Les di...