Canadian Forest Service

About: Canadian Forest Service is a government organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Taiga. The organization has 794 authors who have published 1259 publications receiving 63889 citations. The organization is also known as: CFS.

Application of high-resolution airborne data using individual tree crowns in Japanese conifer plantations

Abstract: We investigated conifer plantation management in Japan using high-resolution airborne data based on an individual tree crown (ITC) approach. This study is the first to apply this technique to Japanese forests. We found that forest resources can be measured at the level of a single tree. We also produced a tree-crown map for a test site with Chamaecyparis obtusa, Pinus densiflora, Larix kaempferi, Cryptomeria japonica, other conifers, and broadleaved trees, with a classification accuracy of 78%. Forest-stand polygons with tree-cover types were generated from this map, a tree-density map, and a crown-occupied-area map. Forest information for the stand polygons was extracted automatically and compared with detailed field-survey data. The error between our ITC estimates and the field-survey data ranged from 0.3 to 30.2%, depending on tree crown size, density, and other factors. Errors were highest for high-density stands with mixed compositions and tree crown diameters ≤5.0 m. However, the error for stands with crown diameters ≥6.2 m was 11.6% or less. Therefore, this technique is best suited to pure Japanese conifer plantations without multiple layers or high-density stands.

Bryophyte abundance, diversity and composition after retention harvest in boreal mixedwood forest

Abstract: Variable-retention harvest is widely recognised as an alternative to more intensive methods such as clear-cutting. However, present information is inadequate to judge the impact of variable-retention on biodiversity of indigenous forest organisms intolerant of canopy removal, such as forest-inhabiting bryophytes. We examined how bryophyte species cover, richness, diversity and composition change with time in response to a broad range of dispersed retention harvest treatments (2% (clear-cut), 10%, 20%, 50%, 75% retention of original basal area) contrasted with uncut controls (100% retention)) in broadleaf deciduous, mixedwood and conifer-dominated boreal forests in North West Alberta, Canada. Bryophytes were studied in 432 permanent sample plots within 72 compartments before harvest and at three, six and eleven years after harvest. Clear-cut and lower (10% and 20%) retention levels resulted in lower cover and richness of bryophytes than in unharvested control compartments in mixed and conifer-dominated forests, but less so in deciduous-dominated forests, which generally supported low cover and richness. Species composition in each forest type varied along the gradient of harvesting intensity; clear-cuts and lower levels of retention supported similar composition, as did control plots and those representing higher retention levels. Over time the retention harvest treatments became more similar to uncut controls Synthesis and applications. Variable retention harvests can better maintain bryophyte biodiversity in managed boreal mixedwood forests, as compared to clear-cuts. We found the efficacy of retention harvest scaled with harvest intensity. Higher levels of retention better moderated the negative impacts of harvesting on bryophyte assemblages across all forest types. Our results suggest, however, that even 10% retention will facilitate faster post-harvest recovery of bryophytes, as compared to clear-cutting. This article is protected by copyright. All rights reserved.

Ecdysteroid and Juvenile Hormone Receptors: Properties and Importance in Developing Novel Insecticides

Abstract: From time immemorial man has been in a state of constant confrontation with insects, his main competitor for food and fiber. The first recorded use of a chemical, sulfur, to control insects can be found in the writings of Homer (before 1000 B.C.). Later, in A.D. 79, Pliny recommended arsenic (Cremlyn 1978). These first-generation inorganic insecticides were later replaced by powerful second-generation organic insecticides, the most notable one being DDT, which was developed by Paul Muller in 1940 (West and Campbell 1950). While the organochlorines enjoyed tremendous success in insect control, their impact on the environment was dramatic, a fact brought to light by Rachel Carson (1962). An intense search for alternatives less harmful to the environment was initiated in laboratories around the world. Carol Williams (1967), the well-known insect endocrinologist, coined the term “third-generation pesticides” for insect hormones such as juvenile hormone and suggested that they could be insect specific and cause little or no harm to the environment. Since then there has been steady progress towards the development of narrow spectrum insecticides that are target specific and environmentally safe. There has also been a surge of interest in biological control agents, led by Bacillus thuringiensis(Bt). The underlying theme has been to search for unique biochemical sites in insect pests that can be selectively targeted. Various approaches are currently being examined; one of these is the hormonal regulation of key developmental processes in insects.

Tissue culture of parasitic flowering plants : Methods and applications in agriculture and forestry

Abstract: Parasitic flowering plants from 23 genera in 7 families (Convolvulaceae, Lauraceae, Loranthaceae, Orobanchaceae, Santalaceae, Scrophulariaceae and Viscaceae) have been cultured in vitro. These plants include both hemiparasites and holoparasites that parasitize stems and roots of angiosperms and gymnosperms. This review highlights relevant information on each genus with regard to its biology, distribution, host range, and tissue culture procedures. Tissue culture has been used to study aspects of the development, metabolism, reproduction, physiology and nutritional requirements of these plants under controlled conditions. Studies of host-parasite relationships, including potential roles of signals/receptors that influence host development and physiology, and factors influencing seed germination and haustorium formation, have been conducted. The effects of chemicals and herbicides on the physiology and biochemistry of parasite embryo and seedling development have been studied, as well as the influence of inhibitors or stimulants on seed germination. Tissue culture has provided a method for propagation and genetic improvement of plants with commercial value.