Spruce budworm (Choristoneura fumiferana (Clem)) is the main defoliator in boreal forest of North America, and its outbreaks have major ecological economic consequences represent a challenge for management. Numerous studies addressed effects this on mature trees, whereas spruce regeneration remain elusive. Furthermore, intensive exploitation practices during last decades left large area Canadia...

Abstract Little information is available on the phenotypic performance of perennial ryegrass varieties when exposed to grazing conditions commercial grassland farms. Grass are classically evaluated in mechanically defoliated plot systems which, although designed mimic conditions, do not fully capture range stresses or interactions that a sward subjected under settings over any period longer tha...

In addition to extreme abiotic conditions, biotic factors such as grazing influence the growth of tundra plants. Strategies of carbon assimilation, accumulation, and utilization must not only satisfy the requirements of a rigorous physical environment but also must simultaneously adjust to the impacts associated with herbivory. Representatives of four growth forms found in northern Alaska (a de...

Dry eucalypt forests are believed to be highly fire tolerant, but their response to fire is not well quantified. We measured the effect of high-severity fires in dry eucalypt forest in the Tasmanian Midlands, the driest region on the island. We compared stand structures and fuel loads in long-unburnt (>15 years since fire) and recently burnt (<5 years since fire) sites that had been completely ...

We describe seasonal patterns of parasitism by Telenomus coloradensis Crawford, Telenomus droozi Muesebeck, Telenomus flavotibiae Pelletier (Hymenoptera: Scelionidae), and Trichogramma spp. (Hymenoptera: Trichogrammatidae), egg parasitoids of the hemlock looper, Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae), after a 3-yr survey of defoliated stands in the lower St. Lawrence region (...

The mapping of changes in the distribution of insect-caused forest damage remains an important forest monitoring application and challenge. Efficient and accurate methods are required for mapping and monitoring changes in insect defoliation to inform forest management and reporting activities. In this research, we develop and evaluate a LiDAR-driven (Light Detection And Ranging) approach for ma...

Glutathione S-transferases (GST) detoxify many electrophilic xenobiotics, including several volatile organic compounds and pesticides. The GST activity for the conjugation of several xenobiotic substances was isolated from needles of Norway spruce (Picea abies L. Karst.) trees from a forest decline stand in the northern alps. Trees that exhibited different degrees of damage were selected from s...

Light controls bud burst in many plants, which subsequently affects their architecture. Nevertheless, very little is known about this photomorphogenic process. This study ascertains the effects of light on bud burst and on two of its components, i.e. growth of preformed leaves and meristem organogenesis in six cultivars from three Rosa species (R. hybrida L., R. chinensis L., R. wichurana L.). ...

1. Herbivore damage can select for tolerance in plant populations where genetic variation for tolerance exists. The causes underlying variation in tolerance are not fully resolved. We assessed the importance of two potential mechanisms for tolerance by examining its relationship with leaf photosynthetic rate and relative biomass allocation across plant organs. 2. We monitored responses of 12 as...

On 14 September 1988 Hurricane Gilbert, the strongest tropical storm ever recorded in the Western Hemisphere, passed through an area of tropical forest in Quintana Roo, Mexico, where I had been studying winter bird populations since 1984. The hurricane defoliated the forest, and created a nearly impenetrable tangle of fallen branches and vines at ground level. Point counts and mist-netting cond...