Effect Of Tree Age Research Articles

Spruce budworm growth, development and food utilization on young and old balsam fir trees.

Laboratory rearing of spruce budworm, Choristoneura fumiferana, in conjunction with field rearing, gravimetric analyses, a transfer experiment, and foliage chemical analyses at six dates during the period of budworm feeding activity indicated that the age of balsam fir, Abies balsamea, trees (70-year-old mature trees or 30-year-old juvenile trees) affected tree suitability for the spruce budworm via the chemical profile of the foliage. Insects reared on old trees had greater survival and pupal weight, shorter development times, and caused more defoliation than those reared on young trees. Young trees were more suitable for the development of young larvae (instars 2-5), while old trees were more suitable for the development of older, sixth-instar larvae. These results were confirmed by the laboratory transfer experiment. Young larvae fed foliage from young trees had higher relative growth rates (RGR), digestibility (AD), and efficiency of conversion of ingested foliage (ECI) than those fed foliage from old trees. These differences appeared to be related to the high N:tannins ratio, and the high contents of P present in young trees during the development of the young larvae. Old larvae fed foliage from old trees had higher relative growth rates, relative consumption rates (RCR), and digestibility of the foliage than those fed foliage from young trees. The high digestibility of the foliage of old trees was compensated for by a lower efficiency of conversion of digested food (ECD), which in turn resulted in no significant effect of tree age on the efficiency of conversion of ingested foliage by old larvae. The low relative consumption rate of old larvae fed foliage from young trees appeared to be related to the low N:tannins ratio, and the high contents of bornyl acetate, terpinolene, and °-3-carene present in young trees during the budworm sixth instar. Variations in these compounds in relation to tree age may serve as mechanisms of balsam fir resistance to spruce budworm by reducing the feeding rate of sixth instar larvae.

NUTRITIONAL STATUS OF NEW YORK STATE APPLE ORCHARDS

A total of 3850 leaf samples from commercial apple orchards located throughout New York State were submitted for analysis during the 1989-1992 seasons. These included 2583 samples from mature, 968 from young bearing age, and 299 from young nonbearing orchards. Percentages of samples (all ages and all varieties combined) found to be below currently recommended levels were: Zn 75%, Cu 74%, B 68%, Ca 63%, K 60%, Mg 60%, Mn 38%, Fe 19%, N 15%, and P 8%. Percentages of samples found to be above currently recommended levels were: N 21%: Zn 16%, Mn 13%, K 6%, B 4%, Mg 2%, Cu <1 %, and P <l %. Major problems consist of shortages of Zn, Cu, B, Ca, K, and Mg in 60% or more of all samples analyzed. Seasonal, varietal, pest management program, and tree age effects were apparent in the results, indicating that these factors must be considered in interpreting results of leaf sample analyses into recommendations for fertilization programs.

Patterns of cone distribution in crowns of young Piceamariana. I. Effect of tree age on seed cones

The distribution of seed cones on shoots, on branches, and within the crown was determined for young Piceamariana (Mill.) B.S.P. (black spruce) trees aged 6–18 years. The seed-cone zone was restricted to distal 1-year-old shoots until ages 7 and 8. It expanded with increasing tree age, and in association with increases in cone numbers, to include older branches and a great variety of smaller shoots on those branches. By age 18, about 25, 55, and 20% of the cone crop was borne by 1-, 2-, and 3-year-old branches, respectively; hence, a concentration of cones, typical of the species, was maintained near the tree apex. Order 1 shoots bore all cones up to tree ages 7 and 8, but proportions on such shoots decreased with increasing tree age. By tree age 18, order 1, 2, and 3 shoots bore 27, 72, and 1% of the crop, respectively. Seed cones occurred progressively from proximal to distal and finally terminal positions on shoots of different categories following three patterns of decreasing shoot vigour (length). Medial and distal cones were most common. Terminal cones were located only on the weakest shoots within the seed-cone zone.

Effects of Tree Age on Pollen, Seed, and Seedling Characteristics in Great Basin Bristlecone Pine

Seed and pollen were collected from Great Basin bristlecone pine trees (Pinus longaeva D. K. Bailey) at Mammoth Creek (Utah) and the Methuselah Grove (California). Analyses determined whether seed and pollen viability, seed weight and germinability, and seedling biomass decreased with increasing age of the parent tree and whether putative mutations increased with increasing parent tree age. There were significant differences in seed weight and seedling biomass between the two locations. Seed from the Methuselah Grove was lighter and Methuselah seedling biomass was lower at all four harvest dates. However, regression analyses did not identify any relationship between tree age and any variable.

Effects of Tree Age on Secondary Xylem and Phloem Anatomy in Stems of Great Basin Bristlecone Pine (Pinus longaeva)

Effects of Tree Age on Secondary Xylem and Phloem Anatomy in Stems of Great Basin Bristlecone Pine (Pinus longaeva)

Detecting CO2 induced enhancement in the radial increment of trees. evidence from northern timber line

Annual ring data from northern Finland was analysed in order to reveal possible trends in ring width development due to changes in environmental factors. The data was analysed using a four component multiplicative model. The components are: tree age, climatic conditions, tree position and changes in environmental conditions. Since the effect of tree age and position in the stand could be easily eliminated the main problem was thus to eliminate the effect of climatic conditions on ring width. This was based on the dependence of the daily radial increment and daily maximum temperature. The component associated with changing environmental factors, especially to CO2 enrichment, was determined using the model. The basal area development of the trees was calculated from measured and estimated ring widths. Depending on the value of the autocorrelation parameter, the effect of changes in environmental factors on the basal area increment of the trees is between 15.5–43.3 % during the period from 1950 to 1983.

The Impact of an Urban‐Industrial Area on Deciduous Forest Tree Growth

AbstractFactors affecting the height‐growth of white ash (Fraxinus americana L.) and northern red oak (Quercus rubra L.) trees in natural stands were studied within the airshed of an industrial city in central Ohio. Stepdown multiple regression analysis was used to determine the effect of tree age, topography, precipitation, and physical and chemical soil properties on cumulative height‐growth between 1930–76, which included an era of major urban and industrial expansion. Expressions of distance from the city and an index of relative pollutant exposure (RPE), derived in part from the frequency of airflow from the city during the growing season, were also tested as independent variables indicative of relative pollutant dose. Eleven and thirteen significant variables in the final white ash and red oak models explained 63 and 93% of the variation in height‐growth, respectively. Distance from the city and RPE were significant in the models of both species. Significant interactions of these variables with tree age indicated that growth of youngered oaks was more strongly depressed by increasing RPE than was that of older trees; growth of younger, but not older, white ash increased with distance from the city. Red oak growth was unexplainably predicted to be greater nearer the city. Holding tree age and site variables at their means, height‐growth was estimated by the regression models for actual RPE at selected distances and directions around the city. Isopleths constructed from these estimates showed an area of reduced growth northeast of the city in the prevailing wind direction for both species. It appears from this study that height‐growth of forest trees can be measurably depressed as a result of urban influences probably relating to air pollutant exposure.

Salinity and citrus yield—an analysis of results from a salinity survey

SummaryA field survey was conducted to determine the effect of salinity in irrigation water on the yield of orange trees (Citrus sinensis). The part of the survey reported here included 104 sampling sites containing the three variety-rootstock combinations Shamouti orange on sweet lime (Sh × SL), Shamouti on sour orange (Sh × SO) and Valencia orange on sour orange (V × SO). The multiple regression technique was used for the statistical analysis of the data.The analysis yielded multiple regression equations of yield (Y) on salt content of the irrigation water (Cw), soil moisture saturation percentage (SP), the product of the two (interaction term), and qualitative variables (region, tree age, and tree age × Cw interaction). Cw was expressed in terms of chloride (Clw), sodium (Naw) or sodium adsorption ratio (SARW). There was a highly significant correlation between Clw, Naw and SARW, and therefore it was impossible to isolate the effect of each component of salinity. The discussion is given terms of Clw.The regression equation for Sh × SL explained 78% of the variation in Y, in terms of squared deviations from the mean; 20% was due to regional and tree age effects and the rest was due to Clw and SP. Only 42% and 54% of the variability in Y was explained by the regression equations for Sh × SO and V × SO, respectively. Nevertheless, all regression equations had significant R2 values.In all cases the effect of soil texture as expressed by SP and the interaction of SP on Cw was highly significant. The higher the SP value was, the lower was the effect of salinity. For the mean SP value for Sh × SL, there was a yield decrease of 2.31 ton/ha (4.3%) per meq/l increase in Clw. For V×SO, the corresponding yield decrease was 3.25 ton/ha (5.5%) and for Sh×SO there was essentially no effect (actually a slight yield increase).