摘要:

Growth and physiology of layers versus naturally established seedlings of boreal black spruce (Picea mariana(Mill.) BSP) were compared 15 years after a cutover in Quebec. During the first 8 years, height growth of seedlings was greater than that of layers, averaging 10.4 and 7.0 cm/year, respectively. For the last 5 years, annual height growth of layers and seedlings did not differ (25 cm/year;p> 0.05). Over the entire 15-year period, total height growth of seedlings (251 cm) was greater than that of layers (220 cm), although total height did not differ (p> 0.05) over the last 6 years. During the 15th growing season, there were no differences (p> 0.05) for predawn shoot water potential, stomatal conductance, net photosynthesis, intercellular to ambient CO2ratio, water use efficiency, and hydraulic conductance between layers and seedlings. For diurnal shoot water potential, seedlings showed slightly less stress than layers on two of the four sampling dates. Thus, in the first few years following the cutover, the slower growth observed for layers indicated that they had a longer acclimation period following the cutover. Afterwards, similar height growth, total height, and physiological characteristics of the two regeneration types indicated that layers can perform as well as naturally established seedlings.

ISSN:0045-5067    

DOI:10.1139/x98-171

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Spring bud development was assessed on cuttings of 17 Norway spruce (Picea abies(L.) Karst.) clones for up to 7 years at two sites in southern and central Sweden. The ability of various temperature models to predict bud-burst timing was analysed. All temperature-based models resulted in significantly better predictions than the null model, day number. Temperature sum (TS) based on a linear response to temperature above a defined threshold, gave a more precise prediction than forcing units based on a logistic response to temperature. The most precise model could predict bud burst to within 2 days, and it included TS with a threshold of 5°C and a start day arbitrarily chosen between January and March. The models were not improved by incorporating chilling, in terms of chilling days (number of days with mean temperature <5°C) or chilling units. It is suggested that chilling requirement is fulfilled already in December under normal winter conditions in southern and central Sweden. Ranking of clones in bud-burst timing was stable over years and sites. For routine measurements of phenology in applied breeding programmes, it is proposed that standard reference material is thoroughly tested for temperature reactions and that this reference material be used each time new material is tested. With this procedure, an accurate estimate of required temperature sum for bud burst can be obtained from a 1-year assessmen

ISSN:0045-5067    

DOI:10.1139/x98-175

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Concentrations of 14 chemical elements (Al, B, C, Ca, Cu, Fe, K, N, Mg, Mn, Na, P, S, Zn) were measured in wood and bark of 126 sample trees representing different stages of decomposition in three major tree species of northwestern Russia: Scots pine (Pinus sylvestrisL.), Norway spruce (Picea abies(L.) Karst.), and birch (Betula pendulaRoth.). Changes in nutrient stores in decay classes were calculated with adjustments for the loss of density and volume by dead trees. Although the concentration of many nutrients increased relative to the estimated initial level, the total amount of most nutrients contained in dead trees declined with decay. For example, nitrogen stores declined from decay class 1 to 4 by 45% for birch, 39% for spruce, and by 60% for pine. The rate and pattern of these losses varied by nutrient and by species and were primarily related to the patterns of bark loss. Pine lost bark early in the process of decomposition and released many essential nutrients (i.e., N, P, Ca) at the early stages, while birch retained most of its bark throughout the decomposition process and lost nutrients more gradually. The temporal dynamics of N, Ca, and K loss in pine were examined using a chronosequence approach, and the results were used in stand-level modeling. The analysis of modeling results suggests that, in northwestern Russia, post-disturbance release of nutrients from woody detritus can potentially supply a large proportion of the net N, Ca, and K accumulation in live forest biomass.

ISSN:0045-5067    

DOI:10.1139/x98-162

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Härtel's turbidity test (Trübungstest) has been one widely used diagnostic test for air pollution injury for decades. This test is based on the extraction of lipophilic substances into an aqueous suspension, whose light absorption is used as an indication of exposure to pollution. Little is known about the underlying principles controlling the response of the test. In this study, the influence of the cations Li+, Na+, K+, and Ca2+and that of the anions Cl-, Br-, I-, and SO42-on the response of Härtel's test was reinvestigated. In contrast to an earlier study, both the extracts' absorbance and acidity were monitored. Additionally, the effects of the Ca-chelating agents ethylenediaminetetraacetate (EDTA) and oxalic acid were compared with that of deionized water and different buffers. All effects of ions including that of Ca2+on the response of the test were accompanied by shifts of the extracts' acidity. Even small changes in the pH caused significant variations in the test's response. On the other hand, addition of the Ca chelating agents EDTA and oxalic acid to the solvent did not affect the response of the test when the pH was equal to solvents without Ca chelating compounds. Therefore, the previously published assumption that the availability of Ca2+could be the main principle of the test's reaction mechanism was not confirm

ISSN:0045-5067    

DOI:10.1139/x98-176

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Seasonal development of apical mitotic activity and growth in three clones of Norway spruce (Picea abies(L.) Karst.) of the same age and origin but with differences in accumulated height growth and cold hardiness were investigated. The clones showed no consistent difference in mitotic index (MI), either in period or in general levels. The response of MI to temperature differed in spring and fall. Differences in cold hardiness between the clones was not directly coupled to differences in MI. Diameter growth ended earlier in one clone than in the other two clones, and this clone also produced lower numbers of stem units in both lateral and leader shoots. Cessation of diameter growth showed no relation to the duration and level of apical MI. The tallest clone had, as a combined effect of both size and number of stem units, significantly longer leader shoots than the other two clones. The greater leader shoot growth of the tallest clone relative to the other two clones during 1987-1996 was also most prominent after years with sudden drops in fall minimum temperatures to below ca. -12°C (median; interval: -11 to -13°C), following several weeks with mean temperatures above 3

ISSN:0045-5067    

DOI:10.1139/x98-177

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Early spring buds of silver birch (Betula pendulaRoth), collected with and without a female catkin in the middle of April, were cryopreserved using slow cooling followed by immersion in liquid nitrogen at -196°C for 8 days, 6 months, 1 year, 3 years, or 5 years. After fast thawing the buds were cultured in vitro according to the published protocol. The regrowth ability of the two types of buds was different. The regrowth of vegetative buds without a female catkin was good after all the cryopreservation times. There was a significant decrease in the regrowth ability of buds growing in the axil of a female catkin compared with the corresponding unfrozen controls after 1 year in cryostorage. In addition to the effect of the presence of a catkin on the regrowth ability, the late collecting time of the buds also probably decreased the regrowth and regrowth rates of both types of bud. The regrowth rates of buds without a catkin were 66, 67 and 24% after 1, 3, and 5 years of cryostorage, respectively, while those of buds with a catkin were 13.5, 32, and 2.6%, respectively

ISSN:0045-5067    

DOI:10.1139/x98-178

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The spatial variability of soil aeration (aerobic limit depth and oxygen diffusion rate (ODR)) among different drainage ditch spacings and at various distances from drainage ditches was examined at two peatlands drained for forestry in north-central Alberta. Drainage lowered mean water table levels (p< 0.001) at both peatlands. Lower water table levels within drained areas were associated with greater aerobic limit depths (p< 0.001) and greater ODR (p< 0.001 at Saulteaux River;p< 0.027 at Wolf Creek) compared with undrained areas of both peatlands. Spatial patterns of aerobic limit depth and ODR indicated strong spatial variability of soil aeration in the immediate vicinity of drainage ditches. However, little sensitivity of soil aeration to different ditch spacings was evident. Potential effects of post-drainage subsidence on soil aeration was evident as increased distance of both the aerobic limit, and near-zero oxygen diffusion rates above the water table surface at both peatlands. One effect of post-drainage peatland subsidence may be to increase the thickness of the capillary zone above the water table. However, reduction of aeration within the rooting zone of peatland trees due to subsidence was not observed because of low water tables within the drained areas of both peatlands.

ISSN:0045-5067    

DOI:10.1139/x98-179

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The extent to which parent trees within breeding zones of coastal Douglas-fir (Pseudotsuga menziesiivar.menziesii(Mirb.) Franco) are locally adapted to their native environments was evaluated. Forty families from each of one Coastal and one Cascade breeding population in Oregon were assessed for cold hardiness and growth phenology, and family means for traits were summarized using principal components analysis (PCA). Composition of the first two principal components (PCs) was consistent between breeding zones, years, and test sites. PC-1, describing 39-46% of trait variation, represents a suite of traits related to spring phenology and spring cold hardiness. PC-2, describing 20-22% of trait variation, consists of cold-hardiness traits not associated with phenology. The first two PCs from each population, as well as univariate traits, were regressed on parent tree location variables and modeled climatic indices separately. In the Coastal zone, PC-1 was weakly but significantly related to temperature and moisture regimes (0.176r20.235), varying with elevation and distance from the ocean. PC-2 was related to temperature and moisture regimes in both populations (0.087r20.249). These relatively weak geographic patterns for adaptive traits within breeding zones suggest that current zone size is not excessive and could likely be increased north or south.

ISSN:0045-5067    

DOI:10.1139/x98-180

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Pin cherry (Prunus pensylvanicaL.) develops an early height advantage over associated species. Data from three long-term studies, extending up to 70 years after complete overstory removal, were used to evaluate the effects of pin cherry density on associates. Survival of seedling-origin stems of black cherry (Prunus serotinaEhrh.), red maple (Acer rubrumL.), and sugar maple (Acer saccharumMarsh.) at age 15 decreased as the density of pin cherry >1.5 m tall at age 3 increased. The regression of pin cherry with black cherry was particularly strong (R2= 0.632). Height of the tallest black cherry and white ash (Fraxinus americanaL.) at age 15 also decreased. If the density of pin cherry at age 3 was > 1 stem > 1.5 m tall per 0.0004 ha (high density), the number of black cherry fell below full stocking at age 15. When pin cherry occurred in high density, it lived longer than when it occurred at low density (< 1 stem > 1.5 m tall per 0.0004 ha). High pin cherry density early in stand development delayed the time when shade-intolerant and shade-intermediate species reached a stable proportion of the total basal area. In the long term, pin cherry reduced stand diameter and volume growth, particularly of black cherry.

ISSN:0045-5067    

DOI:10.1139/x98-181

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Nutrient storage is an important aspect of resprouting potential and production ofSalix viminalisL., a pioneer species used for biomass production in Sweden. Seasonal dynamics of nitrogen (N), protein, soluble carbohydrates, starch, and lipids were studied in roots, cuttings, stems, and leaves during a full growth cycle induced by varying photoperiod and temperature in a growth chamber. Nitrogen was supplied at two rates. Both season and N availability significantly affected storage of N and carbohydrates. Reserves peaked in dormancy, and plants grown at a higher N availability were able to build up larger N reserves, whereas carbohydrate reserves were similar in the two N treatments. All perennial plant organs functioned as storage sites for N. Roots were prominent in carbohydrate storage, in good agreement with the notion of a pioneer species adapted to recurring disturbance by a pronounced resprouting capacity. Roots differed from aboveground plant parts in their exceptionally high starch levels, and in that N storage in roots to a greater extent involved nonprotein compounds. Triglycerides contributed to carbon storage in aerial plant parts but not in roots. Our results suggest that an increased N supply enhance both the accumulation of nutrient reserves and early season growth.

ISSN:0045-5067    

DOI:10.1139/x98-183

出版商:NRC Research Press    

年代:1999

数据来源: NRC