摘要:

Three field experiments were carried out to assess the performance of 1.5 + 1.5 black spruce (Piceamariana(Mill.) B.S.P.) transplants and FH508 Japanese paperpot seedlings in relation to various levels of chemical site preparation with Pronone® (granular hexazinone) applied during the winter to 4700 trees on shear-bladed, imperfectly drained stone-free clay and clay loam soils. Second- and 3rd-year assessments revealed that both stock types responded similarly to chemical site preparation. Growth data were fitted to linear and, where appropriate, quadratic response models. The response of planted seedlings was positive and generally linear over the range of dosages (0 to 6 kg active ingredient/ha) applied. Chemical site preparation had little or no effect on survival of either stock type. In comparison with the transplants, the paperpot seedlings were in better condition and were of a similar size at the end of the assessment period.

ISSN:0045-5067    

DOI:10.1139/x90-205

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

A new soil sampling method using glass jars to measure zero-time herbicide residues was compared with a conventional method using a soil corer under forest conditions in northern Alberta. A liquid formulation of hexazinone was diluted 20 times with water and applied with a four-nozzle overhead backpack sprayer. Use of the glass jar method resulted in 5 times more efficient recovery of hexazinone residues from soils (3.8 kg/ha) than the conventional corer method (0.8 kg/ha) at zero time. The corer method should be used following soil penetration of residues. Subsurface (0–30 cm) hexazinone levels sampled by this method were determined to be 2.0 and 0.35 kg/ha, respectively, 210 and 360 days after application. The combined use of glass jars for zero time and the soil corer for subsequent samplings produced the best result in estimating the dissipation rate of hexazinone in forest soils. Because of the late application in the fall and frozen ground in winter, the dissipation time for 50% of hexazinone was 206 days.

ISSN:0045-5067    

DOI:10.1139/x90-206

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The effect of water table depth (10, 20, and 40 cm) in association with marsh reed grass (CalamagrostisCanadensis(Michx.) Beauv.) on white spruce (Piceaglauca(Moench) Voss) 2 + 0 seedling survival and growth was tested over a 5-month period. All spruce seedlings grown alone survived, whereas, 16.7% of the trees died when grown with reed grass. The root weight and total weight of spruce seedlings and marsh reed grass were significantly affected by the water table depth. The weight of both components increased as the water table decreased. Over 80% of the roots by weight for both species were found in the upper 10 cm of the soil profile regardless of water table depth. The presence of marsh reed grass significantly affected the growth of spruce seedlings. The nutrient concentration of the white spruce foliage was significantly affected by water table depths and the presence of grass.

ISSN:0045-5067    

DOI:10.1139/x90-207

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300 m within the Rincon Mountain Wilderness of Saguaro National Monument, Arizona, United States. Cross-dating of the remnant material allowed dating of fire events to the calendar year. Estimates of seasonal occurrence were compiled for larger fires. It was determined that the fire regime was dominated by large scale (> 200 ha), early-season (May–July) surface fires. The mean fire interval over the Mica Mountain study area for the period 1657–1893 was 6.1 years with a range of 1–13 years for larger fires. The mean fire interval for the mixed-conifer forest type (1748–1886) was 9.9 years with a range of 3–19 years. Thirty-five major fire years between 1700 and 1900 were compared with a tree-ring reconstruction of the Palmer drought severity index (PDSI). Mean July PDSI for 2 years prior to fires was higher (wetter) than average, while mean fire year PDSI was near average. This 490-year record of fire occurrence demonstrates the value of high-resolution (annual and seasonal) tree-ring analyses for documenting and interpreting temporal and spatial patterns of past fire regimes.

ISSN:0045-5067    

DOI:10.1139/x90-208

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

An ecological multifactor approach was used to identify and describe oak ecosystem types in highly disturbed landscapes and fragmented forests in an area of over 19 000 km2in southeastern Michigan, United States. Eleven upland ecosystems and 1 wetland ecosystem were identified in the field using reconnaissance, plot sampling, and test mapping. Each ecosystem type was a characteristic combination of physiography, soil, and climax vegetation (overstory and ground-cover vegetation). The ecological approach emphasized physiographic and soil factors because of the disturbed state of the vegetation. Of 222 species of ground-cover vegetation, only 68 were used in forming the 13 ecological species groups. White oak (QuercusalbaL.) exhibited the largest ecological amplitude of the three major oak species; it occurred on dry to mesic sites. Red oak (Q.rubraL.) occurred on dry-mesic to mesic sites, and black oak (Q.velutinaLam.) was restricted to dry sites. Discriminant analysis was used to examine the distinctness of the upland ecosystems and to compare the error rates of different ecosystem components. The misclassification rates obtained by using all ecosystem components (physiography, soil, ecological species groups, and overstory vegetation) were the lowest: 20% in highly dissected terrain and 34% in flat to gently rolling terrain. However, results obtained with physiography–soil and ecological species group variables were nearly as good as results that added the overstory vegetation. More overlap among ecosystem types and higher misclassification rates were found than in ecosystems of old-growth forests of northern Michigan and oak forests in southwestern Wisconsin where similar methods were used. Nevertheless, for the highly disturbed forests of southern Michigan, the ecological, multifactor landscape approach is a useful and effective method of identifying, describing, and mapping ecosystem types.

ISSN:0045-5067    

DOI:10.1139/x90-209

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Fertilizer was applied on snow in January 1981 at 100 kg N•ha−1as [15N]urea,15NH4NO3, and NH415NO3to 11-year-old lodgepole pine (PinuscontortaDougl. var.latifoliaEngelm.) at Spillimacheen in the British Columbia interior and as [15N]urea (200 kg N•ha−1) to 13-year-old Douglas-fir (Pseudotsugamenziesii(Mirb.) Franco) at Green Mountain, a coastal site in British Columbia. Recovery of labelled N after one growing season was determined in soil and biomass at both sites, and it was also monitored during the growing season in snow and soil at Spillimacheen. At Green Mountain, 5.5% of urea N was recovered in tree biomass, 10.8% in understory, and 33.4% in soil organic N (total recovery 49.7%). Leaching may have contributed to N losses at Green Mountain, but was probably not a direct consequence of the application on snow. At Spillimacheen, total recovery of [15N]urea was 93.3%, with 10.1% in tree biomass, 2.4% in understory, and 80.8% in soil. For15NH4NO3, recoveries were 5.3% in tree biomass, 2.9% in understory, and 87.0% in soil, for a total of 95.2%. For NH415NO3, recoveries were 1.9% in tree biomass, 3.4% in understory, and 39.1% in soil, for a total of 44.4%. At Spillimacheen, the performance of15NH4NO3was comparable to that of urea in tree uptake and soil retention. There were large losses with the NH415NO3source, however, most likely due to leaching and denitrification during snowmelt. For this reason, fertilization with nitrate on snow is not recommended because of nitrate's susceptibility to leaching, but urea and ammonium sources may be applied under these conditions.

ISSN:0045-5067    

DOI:10.1139/x90-210

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

A probabilistic model predicts means and variances of the total number and volume of large woody debris pieces falling into a stream reach per unit time. The estimates of debris input are based on the density (trees/area), tree size distribution, and tree-fall probability of the riparian stand adjacent to the reach. Distributions of volume, length, and orientation of delivered debris pieces are also predicted. The model is applied to an old-growth coniferous stand in Oregon's Cascade Mountains. Observed debris inputs from the riparian stand exceeded the inputs predicted from tree mortality rates typical of similar nonriparian stands. Debris pieces observed in the stream were generally shorter, with less volume per piece, than those predicted by the model, probably because of bole breakage during tree fall. As a second application, predicted debris inputs from riparian management zones of various widths are compared with the input expected from an unharvested stand.

ISSN:0045-5067    

DOI:10.1139/x90-211

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Using periodic remeasurements of tagged trees in nine 0.4-ha sample plots in aPiceasitchensis(Bong.) Carr. –Tsugaheterophylla(Raf.) Sarg. forest at Cascade Hand Experimental Forest, Oregon, we calculated that biomass of bolewood increased from 570 Mg•ha−1at age 85 years to 760 Mg•ha−1at age 138 years. Net primary production of bolewood declined from 11 to about 6 Mg•ha−1•year−1, and mortality loss increased from 2 to about 6 Mg•ha−1•year−1. Values for 37-year-old plots in the same area were 210–360 Mg•ha−1•year−1bole biomass, 7–20 Mg•ha−1•year−1bolewood production, and 0–2 Mg•ha−1•year−1mortality loss. Indications are that bolewood production and biomass were lower in the older plots when they were 37 years old. In the older plots, biomass did not increase between ages 120 and 138. Of the photosynthate potentially available for bolewood production, some replaces biomass lost via mortality and some is allocated to maintenance (respiration plus allocation to fine roots). We estimate that one-quarter to one-half of the production is lost by mortality, and that mortality loss may thus be an important factor limiting forest biomass accumulation.

ISSN:0045-5067    

DOI:10.1139/x90-212

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

A decline in germination capacity (vigor) ofQuercusnigraL. (water oak) seed lots within 108 h was observed when seeds were aged at 41 °C and 100% relative humidity. Aging for less than 108 h increased germination rate. Seed moisture and amino nitrogen contents increased with period of aging, whereas starch content gradually declined. There was no definitive pattern of change in the contents of reducing and nonreducing sugars. These changes reflected an overall elevated metabolism that resulted in an increased rate of utilization of seed energy reserve and a consequent decline in seed vigor.

ISSN:0045-5067    

DOI:10.1139/x90-213

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Basal-area increment and height growth of 30-year-old red spruce (PicearubensSarg.) from 12 rangewide provenances growing in a plantation in northern New Hampshire were measured for a 3-year period (1986 through 1988) in which severe and (or) frequent winter damage to needles occurred. Growth of uninjured trees and injured trees were compared. Basal-area increments were successively smaller for groups of trees arranged in increasing order of average needle damage as a portion of the upper crown and number of years that the trees were injured. A similar pattern was observed for height growth, but the effect of winter damage was not as great on height growth as on basal-area increment. Growth losses following winter injury, especially height growth, were much greater for trees in provenances classed as pure red spruce than for trees in provenances where introgressive hybridization with black spruce (Piceamariana(Mill.) B.S.P.) has been demonstrated. For pure red spruce populations, repeated injury in 3 successive years or a sustained average of 30% or more needle damage resulted in losses in basal-area increment and height growth of up to 59 and 30%, respectively. Basal-area growth of the most severely injured trees in New England - New York provenances was 63% less than that of uninjured trees. These results support the contention of others that winter injury could be an initiating or perpetuating factor in red spruce decline.

ISSN:0045-5067    

DOI:10.1139/x90-214

出版商:NRC Research Press    

年代:1990

数据来源: NRC