摘要:

The name Pinus caribaea was fust used by Morelet in 1851 to refer to a species of pine in southeastern United States whose range included northern Central America, the Bahama Islands and Cuba. Later this species was separated from those in Central America, the Bahama Islands and Cuba, and identified as Pinus elliotri Engelm. The species in Central America, the Bahama Islands and Cuba retained the name Pinus caribaea. Subsequently, Pinus caribaea was separated into three varieties: caribaea, bahamensis, and hondurensis. The hondurensis variety has been the most widely introduced in plantations in the tropical and subtropical regions of the world; it grows vigorously in the various climates of the tropics and fonns more than 80% of the world's plantations listed under Pinus caribaea. Unfortunately the species is associated with poor seed production outside its native range, and all regeneration methods adopted to grow the species have not been fully satisfactory except for regeneration from seed. Latitudinal displacement resulting from the large scale introduction of the species outside its natural range has been identified as the primary cause of poor seed production of the species outside its native range. The species has recently been successfully regenerated in tissue culture, but genetic instability of roots of culture regenerated seedlings that is induced by high concentrations of exogenous auxins used in rooting remains a problem. In addition to the elevated nuclear DNA produced in tissue culture the species has ontogenetically elevated nDNA in the nuclei of the dormant embryos which upon germination migates to the cytoplasm and is metabolized. The significance of this elevated nDNA in the perpetuation of the species and its possible relation to the elevated DNA in tissue culture are discussed.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_01

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Two sets of large (8-20 m tall) red spruce (Picea rubens Sarg.) trees growing on Whiteface Mountain, N.Y., were used in branch chamber experiments. In the summer of 1988, the treatments were made on four healthy trees and consisted of: (1) open branches (N), and in chambers that were supplied with either: (2) ambient air (A); (3) charcoal-filtered air (T); or (4) charcoalfiltered air and deionized water misting when the forest was immersed in ambient cloud water (M). Each tree had all of the treatments. The treatments for the second year (summer of 1989) were made on four declining trees and consisted of: (1) open branches (NC) and chambers supplied with either (2) ambient air and mist (AA), (3) synthetic acid mist and ambient air (SA), (4) distilled water mist and ambient air (DA), (5) synthetic acid mist with filtered air (SF), and (6) distilled water mist with filtered air (DF). Foliar properties measurcd included: (1) microreflectivity, a measure of surface wax properties; (2) cuticle thickness; (3) cutinized cell wall thickness; (4) total cuticular layer thickness: (5) the mass of surface wax extracted from needle samples; and (6) contact angles, a measure of surface wetting. In addition, needles were collected and measured from healthy trees at lower and higher elevations. In the first experiment, reflectance from the wax in the stomata1 antechambers in treatment M was statistically significantly greater than all the other treatments. The cuticles of needles in treatment M were also statistically significantly thicker than the cuticles measured in all the other treatments (40% thicker than for the open branches). A plot of cuticular layer against elevation showed that the two filtered chambers (M and T) provided environments for cuticle development that mimic lower elevations. In 1989 the weather was cooler and more moist, and although the trees used in 1989 were declining, the results were similar to those of 1988. However, the additional treatments with synthetic acid mist resulted in reduced cuticle thickness. While the cuticles of the chamber trees growing at 1,170 m were, except for treatment M and T, generally thicker in 1989 than in 1988, they were still considerably thinner than those of spruce trees growing at the lower elevations. These results suggest regional scale air and precipitation quality have detrimental effects on red spruce needles at Whiteface Mountain.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_02

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Protecting areas of native forest as we convert Nature's landscape to humanity's cultural landscape is critical, because the sustainability of the diversity and the functional dynamics of the patterns we create on a landscape will ultimately determine not only the ability of the forest within itself and within the context of the landscape to adapt to changing environmental conditions, such as global warming, but also the ability of the landscape as a whole to adapt to such changing environmental conditions. The long-term sustainability of the forest is therefore nested within the long-term adaptability of the landscape of which it is a component.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_03

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A simple stand model is developed to assess the influence of management activities in old growth Douglas-fir forests on atmospheric CO, levels. Two natural disturbance regimes (450- and 240-year stand replacement fire cycles) are compared with four management regimes (45, 6 5 , 90-year plantation rotations, and conversion to non-forest use). Conversion of old growth Douglas-fir stands to plantations may actually decrease atmospheric C 4 for the fist few decades, but then increase it. The short term and long term changes are negligible compared to the atmospheric C02 produced by burning fossil fuels. Using wood as a substitute product for other materials (brick, aluminum, and plastic) dramatically reduces CO, released to the atmosphere; however, where wood is used as a luxury product, large quantities of C02 are released to the atmosphere under harvest regimes.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_04

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Green ash (Fraxinur pennrylvanica) and white pine (Pinus strobus) trees were planted on three minesoil types (graded topsoil, graded and ripped topsoil and levelled gay cast overburden) with various mixtures of masses and legumes seeded either before tree planting or at time of bee planting. Trees received weed control for either 0, 1 or 2 years. Some trees were also planted on unseeded subplots. Survival,-vigor and annual height giowth of trees were measured as well as biomass and ground cover of herbaceous species. After two growing seasons with above average precipitation, green ash had excellent survival at 98% but white pine averaged 36% survival overall and only 6% on cast overburden. However, cast overburden was a suitable soil for green ash, and biomass of seeded gasses and legumes was equal to that found on topsoiled plots in the second growing season. Treatments such as weed control, ripping compacted topsoil and delay of seeding until tree planting normally result in increased tree seedling survival (as was the case in an earlier study established during a drought year) but these treatments provided little benefit to trees in this experiment probably because soil moisture was abundant during both growing seasons.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_05

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The objective of this study was to compare the interaction between Frankia and vesicular-arbuscular mycorrhizae (VAM) on the growth response of Alnus acwninata H.B.K. seedlings under three different phosphorus levels. Alnus acuminata seedlings grown in sterile vermiculite, were inoculated with Frankia strain HFPArI3 and/or VAM (as Glomus inwa-radices) under three phosphorus levels (10.50 and 100 pg g'). After 120 days diiferences in growth were observed at the 50 pg g" P level between nodulated and non-nodulated plants; whether inoculated with Frankia + VAM or just with VAM. Interaction between Frankia and VAM was positive with respect to nodule weight at 50 pg g7' P level. The data suggest that the presence of VAM can compete with the nodules as a carbohydrate sink. At increasing levels of P the presence of Frankia alone statistically increased growth over that of the control.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_06

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

No abstract available for this article.

ISSN:1054-9811    

DOI:10.1300/J091v01n01_07

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor