Early growth of lodgepole pine after establishment of alsike clover–Rhizobium nitrogen-fixing symbiosis

1992 ◽  
Vol 22 (8) ◽  
pp. 1089-1093 ◽  
Author(s):  
R. Trowbridge ◽  
F.B. Holl

An overdense lodgepole pine (Pinuscontorta Dougl. ex Loud.) stand was knocked down and the site was prepared by broadcast burn, windrow burn, or mechanical forest floor removal. Inoculated alsike clover (Trifoliumhybridum L.) was seeded at 0, 10, 20, and 30 kg/ha for the three different site preparation treatments to determine the effects of (i) site preparation on infection and effectiveness of the clover–Rhizobium symbiosis and clover percent cover and (ii) the clover–Rhizobium N2-fixing symbiosis on survival, early growth, and foliar nitrogen concentration of lodgepole pine seedlings. The N2-fixing symbiosis established well in all treatments. Clover percent cover increased with increasing rate of seeding, although by relatively few percent in the clover seeded plots. Broadcast burning, windrow burning, and mechanical forest floor removal did not affect the establishment of the N2-fixing symbiosis or clover percent cover. Lodgepole pine survival was not affected by the seeding treatments in any year, nor were height measurements during the first three growing seasons. Seedling height was slightly less in clover-seeded plots compared with controls in the fourth growing season. Lodgepole pine seedlings on clover-seeded plots had decreased diameter growth compared with controls during the first three growing seasons, but incremental diameter growth no longer showed this effect by the fourth growing season. Needle mass (g/100 needles) was less in clover-seeded plots at the end of the second growing season, but this effect was reversed by the fourth growing season, when both needle mass and foliar nitrogen concentration in lodgepole pine foliage were greater in clover-seeded plots.

1990 ◽  
Vol 14 (2) ◽  
pp. 73-76 ◽  
Author(s):  
Mary L. Duryea

Abstract Top pruning, growing-season fertilization, and fall fertilization were investigated in a Florida nursery to determine the effects on crop yield, morphology, nutrition, and field performance. Top pruning improved crop yield by reducing the number of cull seedlings. Top-pruned seedlings were smaller in diameter, height, and weight and had an increased number of multiple tops. In the field, top-pruned seedlings had the same survival and height growth, and after 3 years the percentage with multiple tops was the same as nonpruned seedlings. From these results, top pruning seems to be a nondetrimental practice for controlling height and producing a uniform crop in the nursery. Reducing growing-season fertilization slightly decreased shoot height, but not as much as top pruning. Also, these seedlings had reduced foliar nitrogen (N) concentration and content and grew less after 1 year in the field indicating that cutting back on N in the nursery may not be a beneficial way to control height. Fall fertilization in the nursery increased N in seedlings but did not affect growth or survival in the field. South. J. Appl. For. 14(2):73-76.


1976 ◽  
Vol 6 (3) ◽  
pp. 341-347 ◽  
Author(s):  
S. Thompson

Sequential observations in lodgepole pine (Pinuscontorta Dougl.) and Scots pine (P. sylvestris L.) showed that the second season's shoot was not produced solely from stem units in the terminal resting bud as previously assumed. The stem units held in the rosette of primary needles surrounding the terminal bud elongated to form most of the second season's shoot. The terminal bud only contributed 29 to 54% of the stem units. There was a marked difference between an inland and a coastal provenance of lodgepole pine in the appearance of the shoot apex at the end of the first growing season.


1998 ◽  
Vol 74 (4) ◽  
pp. 578-582 ◽  
Author(s):  
J. M. Kranabetter ◽  
R. Trowbridge

Legumes were tested for their ability to increase soil N content and improve growth of lodgepole pine (Pinus contorta Dougl. ex Loud.) seedlings in west-central British Columbia. A trial with alsike clover at varying densities were tested at one site, while three legume species (alsike clover, birdsfoot trefoil, and white clover) were tested on a second site. After five years of legume cover, mineralizable N mass of the forest floor were 0.5 to 4.5 times those of controls. Total N of the forest floor more than doubled in the seeding density study compared with controls, but was insignificant in the multiple species study. Despite observed increases in soil nitrogen, lodgepole pine growth was not enhanced by the legume treatments. Factors such as N immobilization, root distribution, low S levels, and competition for B may have limited the response of lodgepole pine seedlings to additions of biologically fixed-N. Key words: nitrogen-fixation, legumes, lodgepole pine, soil nitrogen


1981 ◽  
Vol 11 (4) ◽  
pp. 789-795 ◽  
Author(s):  
S. Thompson

When seedlings of a single seed source of Scots pine (Pinussylvestris L.) were raised for 26 weeks in a naturally lit, heated greenhouse, two types of shoot morphology were observed. Type 1 was that normally found in 1-year-old seedlings. Type 2 had a shoot morphology similar to that of seedlings raised outdoors for two growing seasons. When compared with type 1 plants, type 2 plants had an earlier start to shoot elongation, set their buds earlier, and stopped shoot elongation sooner. After one growing season, type 2 plants were shorter, had fewer stem units for shoot elongation in the second season, but carried a greater foliage biomass than 1-year-old type plants. After two seasons they remained shorter. Thus, plant rearing practices which result in the production of seedlings with this type of shoot morphology arc undesirable.The relationship between early "budsct," shoot morphology, and plant height suggests that the proportion of seedlings with a 2-year-old shoot morphology after one growing season in a heated greenhouse may be used as an early test for height growth potential in seed origins and possibly in progenies of north temperate pine species.


1979 ◽  
Vol 25 (suppl_1) ◽  
pp. a0001-z0001
Author(s):  
Lewis F. Ohmann ◽  
David F. Grigal

Abstract Three virgin plant communities dominated by Pinus banksiana, three by Populus-Betula, and one mixed community were studied over five growing seasons after burning in the 1971 Little Sioux Fire. From 1971 through 1975 tree and tall shrub reproduction generally decreased in density and increased in biomass. Low shrub cover and biomass increased for 3 years and then leveled off as tree and tall shrub competition increased. Herb cover and biomass increased most rapidly through 1972 and then slowed substantially. By 1975 total net primary productivity averaged 850 g/m²/yr for all seven stands, and over 1,200 g/m²/yr in the broadleaf-dominated stands. The forest floor 01 horizon increased in mass through 1974, and then apparently stabilized at about 620 g/m². The 02 horizon averaged about 1,000 g/m² and was still increasing in 1975. By the 1975 growing season the total amount of nutrients in aboveground vegetation on burned plots ranged from 33 percent of the N to 65 percent of the K found in nearby unburned forest communities. By 1973 the nutrients in the aboveground vegetation and the 01 horizon of the forest floor were greater than the quantity estimated to have been mobilized by the fire. The vegetation was an effective sink for the released nutrients.


1999 ◽  
Vol 9 (1) ◽  
pp. 21 ◽  
Author(s):  
Monica G. Turner ◽  
William H. Romme ◽  
Robert H. Gardner

The 1988 fires in Yellowstone National Park providedan opportunity to study effects of a large infrequent disturbance on a natural community. This study addressed two questions: (1) How does prefire heterogeneity of the landscape affect postfire patterns of fire severity? and (2) How do postfire patterns of burn severity influence plant reestablishment? At three sites, 100 sampling points were distributed regularly in a 1-km x 1-km grid and sampled annually from 1989 to 1992. Information was recorded on fire severity (damage to trees, depth of ash and soil charring, and percent mineral soil exposed); pre-fire forest structure (forest successional stage; tree density; tree species; tree size; and evidence of pre-fire disturbance by mountain pine beetle [Dendroctonus ponderosae Hopk.] or mistletoe [Arceuthobium americanum Nutt. ex Engelm.]); post-fire percent cover of graminoids, forbs, and low shrubs; number of lodgepole pine (Pinus contorta var. latifolia Engelm.) seedlings; and general topographic characteristics (slope and aspect). Fire severity was influenced by successional stage, with older stands more likely to be in the more severe burn class, and by tree diameter, with tree damage diminishing with tree size. Prefire bark beetle and mistletoe damage also influenced fire severity; severe prefire damage increased the likelihood of crown fire, but intermediate prefire damage reduced the likelihood of crown fire. Fire severity was not influenced by slope, aspect, or tree density. Postfire percent vegetative cover and density of lodgepole pine seedlings varied with burn severity. In lightly burned areas, percent cover returned to unburned levels by 1991. In severely burned areas, total percent cover was about half that of unburned areas by 1992, and shrub cover remained reduced. Recruitment of lodgepole pine seedlings was greatest during the second postfire year and in severe-surface burns rather than in crown fires. Continued monitoring of vegetation dynamics in Yellowstone’s burned forests will contribute to our understanding of successional processes following a disturbance that was exceptional in its size and severity.


2017 ◽  
Vol 33 (4) ◽  
pp. 386-392 ◽  
Author(s):  
Serena Magagnoli ◽  
Laura Depalo ◽  
Antonio Masetti ◽  
Gabriele Campanelli ◽  
Stefano Canali ◽  
...  

AbstractAgro-ecological service crops (ASC) can increase the vegetation complexity of agroecosystems leading to a positive impact on natural enemies of arthropod pests and on weed control. In this study, two ASC terminations (green manure and roller crimper) and a Mater-Bi-mulched control (MB) were compared in order to describe the effects on pests and beneficial dynamics in an organic vegetable system. The trials were conducted over two consecutive growing seasons in 2014 and 2015. Zucchini were grown as cash crop and barley as ASC. Pests and natural enemies were monitored fortnightly by visual samplings along the whole zucchini-growing season. Zucchini plants showed a faster vegetative growth in MB treatment than in ASC terminations. In both years, MB plots were characterized by higher soil temperature and higher leaf nitrogen concentration resulting in plants more susceptible to Aphis gossypii infestations. In all the experimental plots, natural enemies controlled aphid infestations and no insecticide and sprays were necessary. In conclusion, the tested ASC techniques have been suggested as a tool to mitigate aphid infestation.


2003 ◽  
Vol 18 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Christopher Opio ◽  
Kona van Diest ◽  
Norman Jacob

Abstract Height to diameter ratio (HDR) has been proposed as an alternative to conventional procedures for assessing competition between crop trees and other vegetation. Yet HDRs vary throughout the growing season due to variations in the rate of change in height and diameter. There is an interest, therefore, in determining variations in HDR within a growing season (intra-seasonal changes) and the time of the year when measurements of HDR should be taken for operational purposes. HDR measurements were taken on five occasions at two lodgepole pine (Pinus contorta var. latifolia) sites in the central interior of British Columbia, from early May to late October through the 1999 growing season. Although the focus of the article is the investigation of intra-seasonal changes in HDR, we also compared August 1999 measurements with August 1998 measurements to determine the variation in HDR between growing seasons (inter-seasonal change). The study involved a completely randomized, one-factor experimental design, with replication over time. The removal of competing vegetation (known as brushing) was the factor. The design consisted of four levels of brushing, replicated three times on each study site. The results indicated that HDRs increased from early May to July and then decreased until October to levels equal to or lower than those obtained in August 1998. The highest HDR values were observed in control plots. The analysis of variance (ANOVA) with repeated measures indicated that treatment (brushing radius) and date of HDR measurement had significant (P < 0.05) effects on the intra-seasonal changes in HDR. The results suggest that HDR measurements should be taken either after mid-August, or before mid-May when changes in HDR are negligible. West. J. Appl. For.18(1):52–59.


1979 ◽  
Vol 9 (2) ◽  
pp. 276-283 ◽  
Author(s):  
Nicholas Wheeler

Wind-pollinated seed and ramets from lodgepole pine (Pinuscontorta Dougl.) plus tree selections in British Columbia were established and maintained under 24-h photoperiods for 6 months. Subsequently, these trees were outplanted in the nursery and periodically assessed for height, diameter, and dry weight. Seedlings and grafts developed considerably faster than normal nursery-grown controls during the treatment period, and they maintained an accelerated growth rate during the two growing seasons following outplanting. Root growth was particularly enhanced, as evidenced by the sharply reduced shoot:root ratio of treated seedlings relative to controls. Large differences in growth response existed among wind-pollinated families but family × environment (greenhouse vs. nursery) interaction confounded interpretation. Family performances for treated and control seedlings of the same families were not well correlated (r = 0.24) after two growing seasons. The rapid growth and development of seedlings and grafts under continuous photoperiod can undoubtedly benefit tree improvement programs by ultimately reducing the establishment time of seedling and clonal seed orchards, particularly for slowly growing species such as lodgepole pine.


2009 ◽  
Vol 89 (1) ◽  
pp. 25-34 ◽  
Author(s):  
M. Krzic ◽  
L. Zabek ◽  
C E Bulmer ◽  
B K Chapman ◽  
C. Trethewey

Soils on forest landings are often degraded and unable to support optimal growth of planted conifers unless rehabilitation practices are applied. This study evaluated the effects of tillage and fertilization on soil properties and growth of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seedlings on rehabilitated forest landings in the central interior of British Columbia. Six study sites were rehabilitated in 1998 (but without topsoil replacement) and planted with lodgepole pine in 1999. Tillage treatments were: (i) no tillage; (ii) low intensity (one pass of an excavator and six-toothed rake, target clod size 8–10 cm); (iii) medium intensity (two passes, target clod size 4–7 cm); and, (iv) high intensity (three passes, target clod size 1–3 cm). Fertilizers were applied at the time of planting as slow-release formulations; treatments included: (i) no fertilizer; (ii) NPK-fertilizer; and, (iii) NPK + S-fertilizer. After 5 yr, soil mechanical resistance was higher on the untilled control than the tilled treatments. Neither tillage nor fertilization had any effects on soil chemical properties (total C and N, pH, cation exchange capacity, exchangeable cations). Tillage effects after one growing season were variable; however, after four or five growing seasons, the low-intensity tillage resulted in greater seedling height and diameter growth than the untilled control. After one growing season, fertilization increased seedling height and diameter growth relative to the untreated control, but after four or five growing seasons, fertilization had no effect on lodgepole pine growth. Our findings indicate that a single pass with the excavator and rake was the most suitable rehabilitation practice on these sites. Key words: Forest soil rehabilitation, landing and road rehabilitation, soil conservation, soil degradation, soil compaction, soil productivity


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