摘要:

The volume, biomass, and carbon and nitrogen content of coarse woody debris were measured on three 1-ha reference plots in old-growthNothofagusfusca(Hook. f.) Oerst.–Nothofagusmenziesii(Hook. f.) Oerst. forest on the South Island of New Zealand. Two decay sequences for logs and one for standing dead trees (snags) were recognised from two-way indicator species analysis (TWINSPAN) of up to 30 variables related to physical characteristics and structural integrity. Wood volume (up to 800 m3•ha−1) and biomass were high (up to 300 Mg•ha−1), and the inside-out decay sequence from heartwood to sapwood was unusual compared with that of other temperate hardwood forests. Coarse woody debris represented significant carbon and nitrogen pools, with ca. 150 Mg•ha−1and 370 kg•ha−1, respectively, in one stand. The coarse woody debris component of these broad-leaved evergreen hardwood forests was much higher than that reported for other temperate hardwood forests and approaches that of many northern hemisphere conifer forests. The large coarse woody debris pools are discussed in relation to live stand biomass, natural disturbances and tree mortality, and decomposition processes.

ISSN:0045-5067    

DOI:10.1139/x94-255

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Elongation of shoots in various crown locations, and of individual internodes and leaves of the leading shoot, were recorded at 2-day intervals throughout the 1991 growing season in four clones ofFraxinuspennsylvanicavar.subintegerrima(Vahl) Fern. (green ash). Other trees were disbudded and pruned to a single leader. Using a logistic growth function, nonlinear regression equations were generated and parameter estimates were used to determine maximum growth rates. Terminal leading shoots had a longer growth duration and a greater maximum growth rate than lateral shoots. The pruning treatment resulted in larger shoots, which grew 2–3 weeks longer and had a higher maximum growth rate. Leaf emergence occurred at regular intervals but the rate of emergence varied among clones. Leaf maximum growth rates were not significantly different among clones. Leaf size declined acropetally whereas internode length increased and then decreased. The longest leaves and internodes had the highest maximum growth rates. The size and maximum growth rates of putative preformed leaves were larger than putative neoformed leaves. As a shoot expanded, growth of one internode tended to cease during the linear phase of growth of its associated leaf and that of the succeeding internode.

ISSN:0045-5067    

DOI:10.1139/x94-256

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Vegetative buds and bud-derived calli and suspension cells from 5- to 50-year-old Scots pines (PinussylvestrisL.) were used as targets for biolistic transformation. The gene construct used in the experiments was 35S CaMV–β-glucuronidase (GUS). The highest average level of transient GUS expression was found in suspension cells: 1229 ± 359 (mean ± SE) expressing cells per million. Transient expression was found in 35 of 44 (79%) tree genotypes studied. The expression level in buds and in calli was low: one or two spots per expressing bud. Growth-regulator pretreatment (BAP and 2,4-D) increased the number of GUS-expressing buds significantly. The high transient expression level in suspensions and the high percentage of GUS-expressing genotypes suggest that mature Scots pine tissues have potential for further transformation and genetic regulation studies.

ISSN:0045-5067    

DOI:10.1139/x94-257

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

There is increasing concern over the extinction of plants and animals resulting from modern land-use activities. Many jurisdictions have enacted legislation that limits these activities and directs resource managers to take mitigative steps. In this paper we demonstrate how standard economic analysis can be used to assess the costs of alternative conservation management strategies. The costs of a nest box program for the conservation of an endangered Australian arboreal marsupial, Leadbeater's possum (GymnobelideusleadbeateriMcCoy), are compared with the timber production value of the forests they inhabit. Nest boxes have been suggested as a mechanism to maintain the species and still allow timber harvesting to occur. In most scenarios nest boxes cost more than logging bans even under a variety of discount rates. Thus, given an exogenous policy decision to conserve Leadbeater's possum, the most efficient management strategy in this case is to not harvest the old-growth forests that are likely to support the species.

ISSN:0045-5067    

DOI:10.1139/x94-258

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Diameter structures, diameter–age relationships, and spatial pattern of canopy and understory layers in seven stands representative of mature lodgepole pine (PinusconfortaDougl. ex Loud. ssp.latifolia) forests on gentle (≤5°) slopes in the Taylor Park Basin of Colorado were documented. All stands originated following crown fires 120–140 years ago, during the period of initial Euro-American presence. Two distinct structures were evident among these stands. Four stands had closed canopies (cover >70%), relatively high basal areas and tree densities, low sapling and large seedling densities, numerous standing dead trees, and even-aged diameter distributions. The other three stands had more open canopies (cover <65%), lower basal areas and tree densities, higher densities of saplings and large seedlings, and more even representation across diameter classes. Regeneration tended to occur in small patches in both types of stands. DBH showed a moderate to strong relationship to age in all stands, although suppression of bole-diameter growth was more evident in the closed stands. Structure of the closed stands exemplifies forests that have developed rapidly after canopy fire. Structure of the open stands suggests either low stocking densities following stand-originating crown fires or repetitive surface fires, perhaps reinforced by dwarf mistletoe (ArceuthobiumamericanumNutt. ex Engelm.) infestation, that have allowed more or less continuous recruitment over the past 120–140 years.

ISSN:0045-5067    

DOI:10.1139/x94-259

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

A rapid isolation procedure for intact poly(A)+RNA from Scots pine (PinussylvestrisL.) is described. Translation products of poly(A)+RNA isolated from 6-week-old Scots pine seedlings treated with ozone (0.3 μL/L) for 8 h were analyzed using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Both qualitative and quantitative differences in the translation products were observed after ozone fumigation. Expression of specific mRNAs, coding for stress-induced polypeptides between 12 kD and 50 kD, was demonstrated after 8 h of ozone treatment.

ISSN:0045-5067    

DOI:10.1139/x94-260

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

To determine the relationship between bird biodiversity and succession, we recorded the presence and approximate numbers of breeding diurnal bird species on plots representing secondary vegetation succession in an area classified as the very dry, hot subzone of the Interior Douglas-fir Biogeoclimatic Zone: grass, shrub, young conifer, and mature Douglas-fir (Pseudotsugamenziesii(Mirb.) Franco)–ponderosa pine (PinusponderosaDougl. ex Laws.) forest. The number of species and individual birds increased with the successional age of plots, but young conifer plots had fewer bird species and individual birds than the preceding shrub stage. That is, succession produced peaks in bird biodiversity at the shrub and climax stages. All successional stages, with the exception of young conifer, possessed unique bird species or species found predominantly in that successional stage.

ISSN:0045-5067    

DOI:10.1139/x94-261

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

A section of forest stream was treated withBacillusthuringiensisBerliner var.kurstaki(B.t.k.) at 10 × the expected environmental concentration (200 IU/mL) to determine effects on the macroinvertebrate community. Invertebrate drift density increased slightly (approximately 2-fold over pre-treatment densities), but only during the 0.5-h application and only at the site 10 m below the application point. There were no significant changes in taxonomic richness of benthic invertebrates after the application, but there were short-term alterations in community structure at the treated site after the application, as measured by the χ2dissimilarity index. In 11 of 12 benthic taxa for which there were sufficient data, changes in abundance after the application were not significant compared with changes in abundance at the reference site. The stoneflyLeuctratenuis(Pictet) was significantly reduced (~70%) at the treated site 4 d after the application, and abundance of this stonefly remained considerably lower, but not significantly different, from the reference site for at least 18 d. A follow-up study demonstrated that under laboratory conditions,B.t.k. on leaf material was not toxic toL.tenuis. TheB.t.k. application had no significant effect on the growth or survival of caged caddisfly larvae,Pycnopsycheguttifer(Walker), in the treated stream. Implications of results from this field experiment are discussed.

ISSN:0045-5067    

DOI:10.1139/x94-262

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Our primary objective in this study was to determine if hemispherical (fish-eye) photographs could be used to estimate photosynthetic photon flux density (PPFD) in mature and old-growthPseudotsuga–Tsugaforests in the Oregon and Washington Cascade Range. LI-COR quantum sensors sampled PPFD at 10-s intervals at six points in each of two old-growth stands from January to December of 1991. Direct measures of PPFD were also made with photodiodes, which were calibrated against quantum sensors. They were used to sample PPFD for 6- to 14-day periods during the summer at 15 points in each of four stands, two mature and two old growth. Hemispherical photographs were taken at these sample points and were digitized and analyzed using the programCANOPY. The software predicts overall site openness and openness along the sun path. Regression models were developed based upon those parameters. The models predicted the mean daily PPFD for each month of the year. Two major factors were found that influenced regression models: stand age–structure (mature vs. old growth) and sky conditions (dry vs. wet seasons). Canopies in mature stands were more open than old growth stands, and their PPFD models were more heavily influenced by overall site openness. Conversely, PPFD models for old-growth canopies were more heavily influenced by openness along the sun path. Wet-season models were dominated by diffuse PPFD (overall site openness), and dry-season models were dominated by direct flux (openness along the sun path). Combining data sets from stands of comparable age–structure and seasons considerably increased regressionR2-values.

ISSN:0045-5067    

DOI:10.1139/x94-263

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Transgenic European larch (LarixdeciduaMill.) plants expressing aBacillusthuringiensisBerliner (B.t.) toxin gene or the glyphosate tolerance (aroA) gene have been produced usingAgrobacteriumrhizogenesmediated gene transfer. This procedure relies on direct organogenesis on wounded hypocotyls followingA.rhizogenesinfection. Hypocotyls of seven-day-old larch seedlings were inoculated withA.rhizogenesstrain 11325, harboring the oncogenic nopaline-type pRi11325 and either binary vector pCGN1133 containing 35S NPTII and 35Sssu/aroAor pWB139 containing 35S NPTII–B.t. gene. Adventitious shoot buds were induced 4 weeks after infection. Shoots were excised, elongated, and rooted on selection medium containing kanamycin. Needles from greenhouse-grown plants were confirmed to have and to express theB.t. oraroAgene through Southern, Northern, and Western blot analyses and bioassays. This is the first report of regeneration of transgenic conifer plants expressing value-added genes usingAgrobacterium-mediated gene transfer.

ISSN:0045-5067    

DOI:10.1139/x94-264

出版商:NRC Research Press    

年代:1994

数据来源: NRC