Treesearch

An experiment to determine the interaction of three levels of irrigation, three levels of fertility and three densities of planting was started at the University of California Moreno Ranch in 1982. Differential irrigation and fertility treatments will begin in June of 1983. Some current practices of irrigation and fertilization by southern California growers are discussed.

Abstract - A study was made on 344 miles of logging roads in northwestern California to assess sources of erosion and the extent to which road-related erosion is avoidable. At most, about 24 percent of the erosion measured on the logging roads could have been prevented by conventional engineering methods. The remaining 76 percent was caused by site conditions and choice of alignment. On 30,300 acres of commercial timberland, an estimated 40 percent of the total erosion associated with management of the area was found to have been derived from the road system.

Initial high density (17,200 trees ha-1, 6961 trees a-1) plantations of Eucalyptus grandis yielded up to 22 oven dry tons (ODT) ha-l yr-I (10 ta-1 yr-1) on an approximate 6 month rotation. Border effects could not be eliminated from the small sized plots used. Also within 4 years of planting there were substantial differences in tree vigor and survival such that the effective density was reduced by half. Subsequent plantations of several hardwood species at 5000 trees a-1 and with somewhat better border protection were harvested 2 years after planting; tree survival was greater and in some...

The Nelder Wheel is a single tree systematic experimental design. Its major application is for plantation spacing experiments. The design allows for the testing of a number of spacings in a small area. Data obtained is useful in determining the response of stem diameter and crown diameter to spacing. Data is not compatible with data from conventional plots unless single tree modeling is utilized. The design is sensitive to individual tree losses. Nelder Wheels were planted at Cal Poly, San Luis Obispo with eight species of eucalyptus and a hybrid poplar in 1980. First year growth results...

An evaluation of tree species for energy crops was initiated at two areas in Napa County, California. At one area, Eucalyptus viminalis at 39 months was significantly taller than E. camaldulensis at 50 months. Also evaluated were five clones of Pinus radiata, Juglans regia X hindsii, and Sequoia sempervirens; and these were 1/4 to 1/2 the height of the Eucalyptus species in this time period. At the second area, after 27 months, Eucalyptus camaldulensis was significantly taller and had a larger diameter-at-breast-height than Eucalyptus dalrympleana.

Weeds and weed control are a major problem in the growth and management of Eucalyptus trees. Annual, biennial and perennial weed species are common in sites to be planted. These weeds should be controlled before planting. Preplant, preemergence and postemergence herbicides are discussed. Safe preemergence herbicides include oryzalin, napropamide, oxadiazon, linuron and to a lesser degree simazine, atrazine and diuron. Glyphosate, amino triazole and paraquat have been used safely and efficaceously [sic] postemergence. Combinations of mechanical and chemical weed control help allow maximum...

The authors trace the development of a Eucalyptus reforestation program on private industrial forest land from early testing to production planting. Data is presented on a 14.2 hectare manna gum plantation which has produced an estimated yield of 481 cubic meters/ hectare after 20 years. Because manna gum has about 60 percent greater density than Douglas-fir or redwood, total dry weight yield from such stands may be about 3 times the equivalent of the two native species.

An analysis is made of the break-even price at a 6 percent and 10 percent real interest rate for "intensive" and "minimally managed" scenarios for managing eucalypt energy plantations. The break-even price is greater than the average stumpage price reported for firewood and chipwood by the State Board of Equalization. However, a conversion surplus approach shows that eucalypt firewood plantations are profitable for both the intensive and minimally managed scenario. For plantations producing chips for energy, only the minimally managed scenario, with yields greater than 58 dry tons per acre...