Grazing Values as Related to Tree-Crown Covers

Abstract

Studies were undertaken to determine if approximations of herbage productivity could be made from estimates of tree-crown cover, also whether or not estimates from aerial photographs would be accurate enough for this purpose. Results suggest that there is a sufficiently close relationship between herbage production and crown cover in coniferous stands to make the technique useful in range surveys. Estimation of herbage yields from the ground is too slow to be useful in surveys where large acreages have to be covered in a very short time. Similar results were obtained from ground estimates of crown canopy and those made from aerial photographs. Estimates of herbage yields on a pasture made as a result of the survey were almost identical to those established from an earlier grazing trial.

An overview of the forage resource and beef production on Crown land in British Columbia

“…and sedges averaged 1768 kg ha-land yields on sedge meadow were 1380 kg ha-l (Brink et al 1972). Similar values were reported on Nevis Mountain near Fort Nelson (Brink et al 1972) and in alpine areas near Kamloops (Mitchell et (Nordstrom 1984 (1991) seeded three Montane Spruce cutblocks to orchardgrass, timothy, alsike clover and Dutch white clover at 3 and 12 kg ha-'. In the first year after seeding, forage production equalled 300 kg ha-l on areas seeded at each rate and on the unseeded controls.…”

Landscape-level habitat supply modelling to develop and evaluate management practices that maintain diverse forest values in a dry forest ecosystem in southern British Columbia

“…Understory productivity is tightly coupled to canopy closure (Pase, 1958;Halls and Schuster, 1965;Dodd et al, 1972;Mitchell and Bartling, 1991;Knowles et al, 1999) and the open canopy conditions in fuel management areas benefit livestock and native ungulates. The extensive fuel management scenario easily outperformed all other scenarios, realizing over half the forage production potential on approximately 35% of the forested landscape and providing increased forage for some species of small mammals (Sullivan and Sullivan, 2001;Klenner and Sullivan, 2009) and ungulates (Peek et al, 2002).…”

“…We used crown closure as a surrogate for forage production, based on relationships between crown closure and forage production (Pase, 1958;Halls and Schuster, 1965;Dodd et al, 1972;Mitchell and Bartling, 1991;Knowles et al, 1999). From these studies, the maximum forage production within a forested stand dropped to less than 50% of its potential after crown closure values exceeded 20%.…”

Bases ecológicas para implementar un sistema de uso silvopastoral en la región patagónica de Aysén, Chile

“…En nuestro caso, la producción disminuye en los pastizales de bosques densos por lo tanto la relación de la producción y la radiación transmitida a través del dosel es unimodal. Relaciones similares se han observado previamente en pastizales con arbustos en Norteamérica (Dodd et al 1972, Pieper 1990). La cobertura arbolada puede proporcionar protección contra las condiciones de alta exposición de las praderas abiertas, como la nieve y el fuerte viento, característicos de estas regiones patagónicas.…”