摘要:

This study presents an individual tree height prediction model for white spruce (Piceaglauca(Moench) Voss) and trembling aspen (PopulustremuloidesMichx.) grown in boreal mixed-species stands in Alberta. The model is based on a three-parameter Chapman–Richards function fitted to data from 164 permanent sample plots using the parameter prediction method. It is age independent and expresses tree height as a function of tree diameter, tree basal area, stand density, species composition, site productivity, and stand average diameter. This height-prediction model was fitted by weighted nonlinear regression for spruce and unweighted nonlinear regression for aspen. Almost all estimates of parameters were significant at α = 0.05 and modelR2-values were high (0.9192 for white spruce and 0.9087 for aspen). No consistent underestimate or overestimate of tree heights was evident in plots of studentized residuals against predicted heights. The model was also tested on an independent data set representing the population on which the model was to be used. Results showed that the average prediction biases were not significant at α = 0.05 for either species, indicating that the model appropriately described the data and performed well when predictions were made.

ISSN:0045-5067    

DOI:10.1139/x94-169

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

In 1973, a black spruce (Piceamariana(Mill.) B.S.P.) plantation was established in central Newfoundland on a minerotrophic, open peatland that had been ditched at 1.8 m spacings. The seedlings were planted at spacings of 1.2, 1.8, and 2.4 m and spot fertilized with a mixture of 71 g urea, 99 g ground rock phosphate, and 41 g potassium sulfate. In 1985, 12 years after establishment, concentrations of N (0.90%), P (0.10%), and K (0.28%) suggested that nutrient deficiencies were limiting growth. Consequently, P, P–K, and N–P–K were applied in the amounts of 60 kg/ha P, 100 kg/ha K, and 200 kg/ha N. Controls (no refertilization) were also included in the experiment, although these plots had been spot fertilized in 1973. Between 1985 and 1991, height growth, needle weight, and needle nutrients were not significantly different among planting-spacing treatments. Height growth was greatest in the P–K treatment, whereas needle weights were greatest in the N–P–K treatment in 1987. Uptake of N was significantly improved by application of P–K as well as by application of N–P–K. Concentrations of N, P, and K increased to levels of 2.43, 0.25, and 0.60%, respectively, following application of fertilizers containing those elements. However, by 1991, concentrations had decreased to 1.10, 0.14 and 0.43%, respectively. The effects of refertilization on uptake of Ca, Mg, and Cu were mainly nonsignificant.

ISSN:0045-5067    

DOI:10.1139/x94-170

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Microbial isolates from conifer foliage and strawberry were evaluated for biocontrol ofBotrytiscinereaPers.:Fr. in container-grown seedlings of black spruce (Piceamariana(Mill.) B.S.P.). In growth room assays, seedlings were environmentally predisposed to the pathogen and coinoculated with the isolates andB.cinerea. Sporulation incidence of the pathogen was later estimated on needle segments that were cut from the seedlings and incubated on paraquat–chloramphenicol agar medium. The isolates suppressed sporulation by 0–100%. Those ofAlternaria,Cladosporium,Epicoccum, yeasts, and bacteria were of low to moderate effectiveness, but those ofGliocladium,Myrothecium,Trichoderma, andTrichotheciumwere moderately to highly suppressive. In two greenhouse tests, spore suspensions ofGliocladium roseumLink:Bainier and ofMyrotheciumverrucaria(Alb. & Schw.) Ditm. ex Stendel. (applied three times) at 2- to 3-week intervals suppressed incidence ofB.cinereaby 50–69% and 42–60%, respectively, and were at least as effective as recommended fungicide treatments. Two or three additional applications of the antagonists did not further suppress the pathogen. Isolates ofFusariumsp. andPenicilliumsp. were generally ineffective in the greenhouse tests. The four fungi ranked similarly in biocontrol effectiveness in the growth room and greenhouse. It is concluded that the growth room assay provided a strong indication of biocontrol performance in the greenhouse and thatG.roseumandM.verrucariahave potential for managingB.cinereain black spruce in greenhouses.

ISSN:0045-5067    

DOI:10.1139/x94-171

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Coarse woody debris (CWD) is integral to the functioning and productivity of forested ecosystems. Standing snags and large logs on the forest floor affect soil processes, soil fertility, hydrology, and wildlife microhabitat. Few data are available pertaining to the distribution and abundance of CWD in the managed hardwood forests of the central Appalachians. We surveyed 11 stands, at various stages of development (succession) after clear-cutting (<2, 15–25, 65–90, >100 years old), to evaluate the density, volume, and biomass of trees, snags, and logs under the local forest management regime. As expected, density, volume, and biomass of CWD (stems ≥2.5 cm diameter) were greatest in young stands (<2 years old) immediately following clear-cutting; the vast majority of CWD existed as relatively labile, small-diameter, low decay state logging slash. Young stands retained a few large logs in advanced decay states but observations suggest that these elements were often disturbed (i.e., crushed) by logging equipment during the harvest process. Crushed logs do not function ecologically in the same capacity as large intact logs. A marked decline in CWD was observed in young pole stands (15–25 years old) as slash decomposed. These stands were characterized by a high density of young hardwood stump sprouts in the overstory while maintaining a moderate amount of CWD in middle size and decay states on the forest floor. More mature hardwood stands (65–90 years old) generally exhibited a decrease in live-stem density and an increase in basal area, accompanied by a slight increase in CWD. Commercial thinning presumably limits the contribution of large CWD to the forest floor. This was most clearly evident in the oldest stands (>100 years old) where large CWD was not widely observed. A striking feature across all stands was the near absence of logs in large size classes (>65 cm diameter) and a paucity of logs in mid to late decay stages. We discuss our data in the context of hardwood forest structure and management in the central Appalachians.

ISSN:0045-5067    

DOI:10.1139/x94-172

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Site index is difficult to implement and interpret in multispecies, multiple-aged stands, and its relationship to site factors is obscure. Using data from the USDA forest inventory and analysis (FIA) for the Lake States, we developed log-log relationships between mean tree size and stand density for five cover types. Fits were good, withr2from 0.96 to 0.98 and slopes from −0.948 to −0.995. We define an alternative index of site quality, the relative stocking index (RSI), as the ratio of a stand's measured density to that predicted using the log–log relationship for its cover type (the norm). We divided the range of RSI into three classes for each type (<0.9 of norm, >0.91 but <1.1 of norm, and >1.1 of norm). Based on analyses of the 1977 and 1990 FIA data from Minnesota, class assignments for individual stands remained constant over that 13-year period. Relationships between site factors and either RSI classes or analogous classes based on site index were examined in a subset of 169 stands. Temperature, precipitation, silt content of surface soil, and calculated annual water deficit all differed significantly among RSI classes, but not among site-index classes. The RSI is easy to apply, robust (resistant to change), and related to site factors. It merits additional examination as an index of site quality, especially in heterogenous stands.

ISSN:0045-5067    

DOI:10.1139/x94-173

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Silvicultural practices such as thinning and fertilization can affect both canopy foliage quantity and distribution, altering stand growth. The objectives of this research were to quantify the effects of tree size and silvicultural treatment on the vertical distribution of foliage of individual trees of loblolly pine (PinustaedaL.) and to estimate foliage quantity and distribution using easily measured tree data. In three stands sampled in North and South Carolina, fertilization and (or) thinning treatments had been applied 2 years prior to sampling. A fourth stand was untreated. Nonlinear and linear regression models were developed to test the effects of silvicultural treatment on individual branch foliage biomass and whole tree foliage biomass. Vertical distributions of foliage and branches were modelled using a Weibull probability density function. Analyses indicated that individual branch foliage biomass was positively related to branch size but negatively related to distance from the top of the tree. Fertilization with nitrogen and phosphorus, or thinning, increased the foliage biomass carried by a given sized branch. Silvicultural treatment effects on individual branches translated into whole-tree foliage biomass with thinning and fertilization increasing the crown size of individual trees. Though treatment affected crown size, the distribution of foliage (and branches) remained unaffected. Because silvicultural treatments change the size of crowns for trees of given dimensions, any estimation of loblolly pine crown biomass must be site and treatment specific.

ISSN:0045-5067    

DOI:10.1139/x94-174

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Axenic cultures ofPeridermiumharknessiiJ.P Moore developed white aerial hyphae, orange callus-like growth, and white mycelium colonies as successive vegetative forms when isolated from explants from infected mature field-grownPinusponderosaDougl. ex. P. Laws & C. Laws. Expiants (small cubes of gall phloem tissue) were collected from March through August 1988 and 1989 in eastern Nebraska and northern and western North Dakota. By 20 days after plating, white hyphae appeared to originate from immature aeciospores. By 45 days, friable orange callus-like growth appeared on many explants from beneath the white hyphae and eventually overgrew the latter. Orange callus colonies consisted mostly of single-celled vesicular cells, which seemed to originate from aeciospore initials. The larger vesicular cells were similar in size to aeciospores, contained orange subcellular globules, and occasionally had surface ornamentation similar to that of aeciospores. After 60 days, white mycelium colonies grew as sectors within and at the edges of many orange callus cultures. The colonies appeared to originate as appendages of thick-walled hyphal strands of orange callus and macroscopically consisted of compact masses of thin-walled hyaline hyphae arising from a stroma. If not transferred to fresh medium, orange callus would frequently convert to white mycelium colonies. No change in the morphology of white mycelium colonies was observed. Only mineral salt media supplemented with peptone, soytone, or a mixture of yeast extract, sucrose, and glucose sustained fungal growth apart from the host tissue. Both orange callus and white mycelium colonies grew over a temperature range of 5–35 °C, and revealed similar staining patterns in 12 of 14 isozymes to those ofPeridermiumharknessiiaeciospores when analyzed with starch gel electrophoresis.

ISSN:0045-5067    

DOI:10.1139/x94-175

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (PinusponderosaDougl. ex Laws. var.scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

ISSN:0045-5067    

DOI:10.1139/x94-176

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Three-year-old bareroot white spruce (Piceaglauca(Moench) Voss) seedlings from three seedlots were either lifted in the fall of 1990 and stored over winter at −2 °C, or lifted in the spring of 1991. The soluble sugar, starch, and protein contents of needles, stems, and roots were measured in fall-lifted seedlings before, during, and at the end of cold storage and compared with those in spring-lifted seedlings 10 days before outplanting. The soluble sugar content of the seedlings decreased significantly in all tissues during cold storage. At the time of spring planting, sugar and protein levels were similar in fall- and spring-lifted seedlings, but starch content was about two times higher in spring-lifted seedlings. After outplanting, spring-lifted seedlings flushed and resumed root growth sooner than the fall-lifted, cold-stored seedlings. Spring-lifted seedlings also had initially higher photosynthetic rates and water potentials compared with the fall-lifted seedlings. However, both types of seedlings had similar survival rates and 1st year shoot growth in the field. The responses of seedlings to cold storage were similar among seed lots.

ISSN:0045-5067    

DOI:10.1139/x94-177

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Interior spruce (Piceaglauca(Moench) Voss × PiceaengelmanniiParry) seedlings and emblings (plants produced via somatic embryogenesis tissue culture) were grown as container 1 + 0 plants. Seedling and embling morphological development was monitored during the growing season. Needle freezing tolerance, days to terminal bud break (DBB1), root growth capacity (RGC), and shoot dry weight fraction (DWF) were monitored during the fall and in frozen storage. Emblings had slower height, diameter, and root growth rates during the initial 2.5 months in the nursery. Thereafter, seedlings and emblings had equal height growth rate, while emblings had greater diameter and root growth rates. At the end of the growing season, seedlings and emblings, respectively, had 23.8 and 14.2 cm shoot height, 4.0 and 3.4 mm diameter, and 0.81 and 0.80 g root dry weight. During the fall, DBB1of both seedlings and emblings decreased, with emblings having a more rapid decrease. Both seedlings and emblings showed a similar increase in freezing tolerance. Emblings had a greater increase in DWF. During the fall, RGC decreased then increased, with seedlings displaying a greater increase than emblings. While in frozen storage, seedlings and emblings maintained a low DBB1, and a high RGC and DWF. Freezing tolerance decreased while in frozen storage, with the loss more pronounced among seedlings. A degree growth stage model describes the first year cycle of development for seedlings and emblings. Results indicate that seedlings and emblings have slightly different patterns of first year growth and fall acclimation. However, both seedlings and emblings were at the end of rest when lifted for frozen storage.

ISSN:0045-5067    

DOI:10.1139/x94-178

出版商:NRC Research Press    

年代:1994

数据来源: NRC