Treesearch

Fire is an ecosystem property rather than an exogenous force in southern California chaparral, and it interacts with processes of drought-mediated canopy development, production, and mortality to affect stability of community composition. Where species that must reproduce from seed, such as Ceanothus crassifolius or Ceanothus oliganthus, are predominant, composition can be altered by a single fire with little or no recruitment after initial postfire establishment. Water balance apparently regulates subsequent leaf area development; after 15-22 yr of postfire growth, foliage biomass in...

Up to 25 metric tonnes of seeds of Cook pine, raucaria columnaris (Forst. f.) Hook., are exported from Hawaii in abundant seed years. Excess seeds cannot be stored and used to fill orders in poor seed years because the seeds quickly lose their ability to germinate. The effects of storage temperature, seed moisture content, and nitrogen enrichment of storage containers on short-term and long-term seed germinability were studied in the laboratory. Results confirm the need for storage at near-freezing temperatures and seed moisture contents between 15 and 25%. Filling storage containers with...

Gas samples were collected in smoke plumes over the San Dimas Experimental Forest during a 400-acre prescribed chaparral fire on December 12, 1986. A helicopter was used to collect gas samples over areas of vigorous flaming combustion and over areas of mixed stages (vigorous/transitional/smoldering) of combustion. Sampling was conducted at altitudes as low as 35 m and as high as 670 m above ground level. The samples, collected in 20-L Tedlar bags, were returned by helicopter to our field laboratory and immediately transferred to electropolished stainless steel canisters. Analyses for the...

Smoke aerosol was collected on filters from a helicopter during a 400-acre (1.62 km2) prescribed chaparral burn in the San Dimas Experimental Forest on December 12, 1986. Hi-Vol samplers were used to collect particles on both Teflon and glass fiber filters. Scanning electron microscopy of the filters revealed particles that ranged in size from about 0.1 to 100/µm. Many of the large particles (> 10/µm) that appeared irregularly shaped at low magnifications were found at higher magnification to be highly agglomerated smaller spheres, often showing signs of partial coalescence. Energy...

Drastically reducing populations of feral sheep (Ovis aries), mouflon sheep (Ovis musimon), feral-mouflon hybrids, and feral goats (Capra hircus) on Mauna Kea were key management actions done to promote recovery of critical habitat for palila Loxioides bailleui), an endangered Hawaiian forest bird. Recovery of mamane (Sophora ehrysophyllo), the dominant tree in much of the subalpine woodland and the most important plant species for palila, was studied inside and outside exclosures. Five years after feral sheep and goat popUlations were controlled, natural seed and sprout regeneration had...

Minute-by-minute analysis of point counts of birds in mixed-conifer forests in the Sierra National Forest, central California, showed that cumulative counts of species and individuals increased in a curvilinear fashion but did not reach asymptotes after 10 minutes of counting. Comparison of the expected number of individuals counted per hour with various combinations of counting time and noncounting times (for record keeping and travel between counting stations) showed that 10-minute counts were most efficient in most cases. Counting longer than 10 minutes is not recommended, because of...

DEBRIS is a menu-driven, interactive computer program written in FORTRAN 77 for recording and plotting survey data and for computing hydraulic variables and depths of scour and fill. It was developed for use with the USDA Forest Service's Data General computer system, with the AOS/VS operation system. By using menus, the operator does not need to know any programming language. the five routines are: entering data, plotting scour and fill, hydraulic variables, and computing x-y coordinates.

Trials have been established in Hawaii to develop spacing guidelines for Eucalyptus saligna plantations. Substantial competition-related mortality occurred in densely planted plots of three spacing trials. Data on stand diameter and surviving number of trees on these plots were plotted in logarithmic form to estimate a "self-thinning" or maximum diameter-stand density line. An "operating" maximum line was defined-one representing 70 percent of the total number of trees that could reach any given mean diameter if the stand were allowed to reach the "self-thinning" level. This information...

Eight-year-old Scotch pine (Pinus sylvestris) were severely infected by dwarf mistletoe (Arceuthobium occidentale) when planted near infected Digger pine (P. sabiniana) in the foothills of the northern Sierra Nevada, in California. But 6-year-old knobcone x Monterey (P. attenuata x P. radiata) hybrid pines in the same plantation were unifected. To prevent infection, avoid planting Scotch pines near native California pines bearing dwarf mistletoe.

Little is known about Elytrodema disease (Elytroderma deformans [Weir] Darker) in seedlings or very young trees. Of 100, 2-0 Jeffrey pine (Pinus jeffreyi Grev. & Balf.) seedlings planted in the Taylor Creek area of South Lake Tahoe, about half survived from 1973 to 1987. During this period about two thirds of the surviving seedlings became infected with Elytrodema disease. Of the trees that died, only three were infected with the disease, and none was infected before 1981-82. Earliest infection of surviving seedlings was in 1976, with 1980-81 the only interval without infection. More than...