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1.
影响杉木人工林可持续经营因素探讨 总被引:12,自引:0,他引:12
杉木人工林土壤肥力和林分生产力逐代下降,直接影响杉木林地可持续经营。影响杉木人工林可持续经营的因素是多方面的,主要和杉木人工林所处亚热带红壤区生态系统的脆弱性和杉木人工林群落的单一性及杉木生物学特性等有关,而传统杉木人工林培育过程中采取一系列传统的营林措施则加剧了林地地力衰退。根据目前杉木人工林经营现状,建议在杉木人工林经营过程中应尽量降低营林措施干扰强度,特别是炼山措施的采取;同时开展有关林地可持续模式试验及评价指标体系的研究,以寻找适合不同地区的杉木人工林可持续经营模式。在此基础上,搞好杉木人工林规划和发展,这对南方杉木产区林地可持续经营实践具有较大的指导意义 相似文献
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K. M. S. Sundaram S. Y. Szeto 《Journal of environmental science and health. Part. B》2013,48(5):579-599
Abstract An oil‐based formulation of carbaryl (1‐naphthyl N‐methyl‐carbamate) (Sevin‐2‐Oil) was applied twice by a fixed‐wing aircraft at a dosage rate of 280 g of A.I./ha/application to a coniferous forest near Allardville, New Brunswick. The highest concentrations of the chemical in fir foliage, litter and forest soil 1 h after application were respectively 4.20, 1.21 and 0.59 ppm (fresh weight). The residues dissipated rapidly and the DT50 values obtained from the depletion curves were 2.3 d for foliage and 1.5 d for litter and soil samples. Very low levels (<0.1 ppm) of carbaryl persisted in foliage and litter beyond the 10 d sampling period. The maximum residue level found in stream water was 0.314 ppm and more than 50% of it had dissipated within 1 h. Low but detectable levels (0.001 ppm) of the chemical persisted in water until the end of the 10 d sampling period. Sediment samples contained a maximum level of 0.04 ppm, which dissipated below the detection limit within 5 h. Brook trout and slimy sculpins captured in the stream 1 d after the spray contained on average about 0.04 ppm of carbaryl and none of it was found in 3 d postspray samples. 相似文献
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K.M.S. Sundaram A. Sundaram 《Journal of environmental science and health. Part. B》2013,48(4):757-783
Abstract Dimilin® WP‐25, a wettable powder formulation of diflubenzuron (DFB) [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl) urea], was formulated in four different carrier liquids, viz., water; a light petroleum paraffinic oil, ID 585; a heavy paraffinic oil, Sunspray® 7N; and a 1:2 mixture of a light petroleum aromatic solvent (Cyclosol® 63) and canola oil; to provide four end‐use mixtures, Dim‐W, Dim‐585, Dim‐7N and Dim‐Cy‐C respectively, each containing 28 g of DFB per litre. Balsam fir branch tips clipped from greenhouse‐grown seedlings, and sugar maple branch tips clipped from field‐grown young trees, were exposed to uniform‐sized droplets (ranging in diameters from 135 to 190 μm) of the four end‐use mixtures which were atomized using a monodispersed droplet generator. Droplets were collected on the fir and maple branch tips and the initial residue per g fresh weight of foliage was determined by high‐performance liquid chromatography (HPLC). The branch tips were exposed to cumulative rainfall of 3, 6 and 10 mm at an intensity of 5 mm/h and at time intervals of 1, 12, 36 and 72 h after DFB treatment, to test the influence of ‘ageing’ of foliar residues on rainfastness. Foliar samples were collected for residue determination just before the onset of rainfall, and at 0.5 h post‐rain. DFB was quantified by the HPLC method. In the case of fir foliage, the Dim‐W formulation was the most susceptible to rain‐washing and the rainfastness did not increase with the ageing period of foliar deposits. In contrast, the three oil‐based mixtures showed greater rainfastness depending upon the carrier liquid and the ageing period. Rainfastness decreased in the order of Dim‐Cy‐C > Dim‐7N > Dim‐585 > Dim‐W. In contrast, the data on maple foliage indicated that the ageing of deposits increased the rainfastness of all the 4 end‐use mixtures. Dim‐585 was the most susceptible to rain washing, and rainfastness decreased in the order of Dim‐W > Dim‐Cy‐C > Dim‐7N > Dim‐585. 相似文献
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Gerald F. Gifford William Humphries Richard A. Jaynes 《Journal of the American Water Resources Association》1984,20(2):181-186
ABSTRACT: Heat pulse velocity techniques were developed for effective monitoring of water movement in aspen (Populus tremuloides), subalpine fir (Abies lasiocarpa), and Englemann spruce (Picea engelmannif). Water loss was monitored in replicated trees of each species for one year. These data were used to modify the plant activity index (a reflection of the ability of plants to transpire water at various times during a year) and the crop coefficient (a reflection of differences in consumptive use rates of water by different vegetation types when all other factors are held constant) for each species within the model ASPCON, a deterministic, lumped-parameter model describing the hydrology of aspen to conifer succession. Results of the modeling in dicate 18.6 cm net loss of moisture available for streamflow when spruce replaced aspen, and a loss of 7.2 cm when fir forests replaced aspen. The aspen to conifer successional trend appears, therefore, to be significantly reducing water yields in the western United States. 相似文献
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N. A. Kalashnik 《Russian Journal of Ecology》2008,39(4):261-271
The level of chromosome aberrations at different stages of mitosis has been studied in the seed sprout meristem of four conifer species growing in the Southern Urals in areas differing in the kind and degree of industrial pollution. The results provide evidence for the adverse effect of pollution on the chromosomal machinery of these species. With respect to environmental quality assessment, the Scots pine is the most sensitive indicator species among conifers growing in the Southern Urals and analysis of chromosome aberrations in anaphase-telophase cells is most effective among the cytogenetic methods tested. 相似文献
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Dynamics of soil organic matter in primary and secondary forest succession on sandy soils in The Netherlands: An application of the ROMUL model 总被引:2,自引:0,他引:2
M.A. Nadporozhskaya G.M.J. Mohren O.G. Chertov A.S. Komarov A.V. Mikhailov 《Ecological modelling》2006,190(3-4):399-418
We applied the simulation model ROMUL of soil organic matter dynamics in order to analyse and predict forest soil organic matter (SOM) changes following stand growth and also to identify gaps of data and modelling problems. SOM build-up was analysed (a) from bare sand to forest soil during a primary succession in Scots pine forest and (b) on mature forest soil under Douglas fir plantations as an example of secondary succession in The Netherlands. As some of the experimental data were unreliable we compiled a set of various scenarios with different soil moisture regime, initial SOM pools and amount and quality of above and below ground litter input. This allowed us to find the scenarios that reflect the SOM dynamics more realistically. In the Scots pine forest, total litter input was estimated as 0.50 kg m−2 year−1. Two scenarios were defined for the test runs: (a) forest floor moisture regimes—‘dry, mesic and hydric’ and (b) augmenting a root litter pool with three ratios of needles and branches to roots: 1:1, 1:1.5 and 1:2.0. The scenario finally compiled had the following characteristics: (a) climate for dry site with summer drought and high winter moisture of forest floor; (b) a litter input of 0.25 kg m−2 year−1 above ground and 0.50 kg m−2 year−1 below ground; (c) a low nitrogen and ash content in all litter fall fractions. The test runs for the estimation of the initial SOM pools and the amount and proportion of above and below ground litter fall were also performed in the Douglas fir plantation. The inputs of above ground litter tested in various combinations were 0.30 and 0.60 kg m−2 year−1, and below ground litter 0.30, 0.60 and 0.90 kg m−2 year−1. The scenario that fitted the experimental data had an SOM pool of 20–25 kg m−2, an aboveground litter input of 0.6 kg m−2 year−1and a below ground litter input of 0.9 kg m−2 year−1. The long-term simulation corresponded well with the observed patterns of soil organic matter accumulation associated with the forest soil development in primary and secondary succession. During primary succession in Scots pine forest on dry sand there is a consistent accumulation of a raw humus forest floor. The soil dynamics in the Douglas fir plantation also coincide with the observed patterns of SOM changes during the secondary succession, with SOM decreasing significantly under young forest, and SOM being restored in the older stands. 相似文献
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几种化感物质对杉木幼苗生长的影响 总被引:25,自引:1,他引:25
采用培养皿滤纸法 ,研究了不同浓度的肉桂酸、苯甲酸、对羟基苯甲酸对杉木 (Cunninghamialanceolata)幼苗生长的影响 .结果表明肉桂酸、苯甲酸、对羟基苯甲酸分别在 1× 10 -5molL-1、1× 10 -3molL-1、1× 10 -4 molL-1浓度时降低了叶绿素含量 (P =0 .0 5 ) ,而在 1× 10 -6molL-1、1× 10 -4 molL-1、1× 10 -5molL-1浓度时抑制了杉木幼苗胚根和胚芽的生长 (P =0 .0 1) .3种酚类物质对胚根生长的抑制作用明显高于对胚芽生长的抑制作用 .在 3种酚类物质中 ,肉桂酸对杉木幼苗生长的抑制作用最强 ,对羟基苯甲酸次之 ,苯甲酸最弱 .这表明酚类物质能在不同程度上抑制杉木幼苗的生长 ,降低其生产力 ,可能是连栽杉木人工林生产力降低的因素之一 .图 2表 1参 14 相似文献
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