Treesearch

Fusarium species isolated from necrotic roots of eastern white pine (Pinus strobus) seedlings in two nurseries included F. acuminatum, F. equiseti, F. oxysporum, F. oxysporum var. redolens, F. proliferatum, F. sambucinum, F. solani, and F. sporotrichioides. In addition, all but F. sambucinum were isolated from the rhizosphere; all, in addition to F. graminearum, were also isolated from nonrhizosphere soil. Fusarium oxysporum, F. oxysporum var. redolens, and F. proliferatum were the most prevalent taxa in roots and nonrhizosphere soil. These three taxa plus F. solani predominated in...

Using ideas from landscape ecology, this paper explores how small open spaces can aid urban forestry efforts in dense urban areas. A case study in Chicago illustrates the physical and social lessons learned in dealing with these spaces.

Fragmentation of breeding habitat in North America has been implicated in the decline of forest-nesting, Neotropical migrant birds. We used a comparative approach to examine the effects of fragmentation on three forest-nesting migrants: Ovenbird (Seiurus aurocapillus), Red-eyed Vireo (Vireo ofivaceus), and Wood Thrush (Hylocichla mustelina). We surveyed birds and monitored reproductive success on 28 study plots in fragmented and contiguous forests in two midwestern regions. Distribution of individuals between fragmented and contiguous forests appeared to vary among species and regions, but...

SILVAH, a stand growth simulator commonly used in the northeastern United States, has been evaluated by comparing predicted and actual growth of tolerant hardwoods in southern Ontario. The data came from 139 stands, unmanaged or managed (thinned), even-aged or uneven-aged. The data were used to test the accuracy of diameter distribution, basal area, mean quadratic DBH, number of trees per hectare, and stand volume predictions for periods from 5 to 20 years. The accuracy of short-term basal area projections, expressed by modelling efficiency, ranged from 62% to 94%. The reliability of stand...

Growth and yield projections aid foresters in assessing timber management opportunities and in making management decisions. With these uses, questions arise about the reliability and limits of growth and yield simulators. Using long-term studies of hardwood stands in Ontario the growth simulator FIBER 3.0 has been tested. Short-term (5 years) projections of stand growth are reliable (modelling efficiency from 70% to 90%). Errors for individual stand projections, however, range from -30% to 40%. The magnitude of error in individual stand projections is influenced by species composition and...

Disturbance is integral to the regeneration and growth of northern red oak (Quercus rubra L.) in Ontario, and historically fire has favoured red oak regeneration (Lorimer 1985, 1989, 1993; Abrams 1992; Abrams and Nowacki 1992; Johnson 1993; Van Lear and Watt 1993). In the pre-suppression era, fire was an important disturbance event that affected forest succession and regeneration in Ontario (Cwynar 1977, 1978; Lynham 1985), and many fires burned annually overlarge areas{Howe and White 1913; Cwynar 1977, 1978; MacKay 1978; Ward and Tithecott 1993). More recently, logging has become an...

The artificial regeneration of red oak by planting or direct seeding is an important method for restoring oak in ecosystems where it has been lost as a result of past management practices. Planting and direct seeding can also be used to supplement natural oak regeneration and to ensure that sufficient oak reproduction is in place when overstories are removed through timber harvests. There has been a substantial amount of research conducted on the nursery production of barefoot and container-grown red oak and the direct seeding of oaks throughout eastern North America. This paper is a...

The age, mode of regeneration and diameter growth of white pine were determined in an old growth stand near Dividing Lake, Algonquin Provincial Park. The white pine ranged in age from 267 to 486 years. There was no significant relationship between white pine age and diameter (DBH). The distribution of tree ages indicated that the white pine component in this mixed pinehardwood stand was multi- or all-aged. Most of the pine sampled regenerated during 2 periods (circa 1650 and 1710). However, some pine regeneration occurred throughout the period from 1507 to 1726. Cycles of relatively minor...

Fire-scarred stumps and natural snags of red pine (Pinus resinosa Ait.) on a 70-m tall bluff along Costello Creek, 2 km south of Lake Opeongo, were dated using dendrochronological methods. A fire scar chronology was constructed from 18 of the red pine samples that contained 34 dated fire scars.

Fire scars on stumps of white pine (Pinus strobus L.) in a red oak (Quercus rubra L.) white pine forest near Bracebridge, Ontario, were dated using dendrochronological methods. A chronological record of fires that caused basal scarring is preserved in the remnant white pine stumps, which were estimated to be up to 135 years old. Large cross-sections (1.4 to 0.75 m in diameter) were cut from the solid portion of the stump. Over 100 annual rings per stump facilitated the cross-dating of 72% of the cross-sections. A tree ring chronology between 1664 and 1852 from 21 dated fire scars found in...