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91.
2017年5月10日,将烟台沿海防护林内20~30年生黑松Pinus thunbergii母树的种子分为大粒、中粒和小粒播于花盆中,研究枯落物覆盖厚度(1 cm,2 cm,3 cm,4 cm)对种子萌发和幼苗生长的影响,以阐明沿海黑松防护林幼苗建立的机制。结果表明:种子大小对发芽率、发芽指数有着极显著影响(P<0.01),对平均发芽时间、活力指数没有显著影响。大粒种子比中小粒种子有着低的发芽率和发芽指数。在生物量分配和根系特征上种子大小没有显著影响,但对幼苗高度和地径有显著的影响(P<0.05),都是大粒和中粒种子大于小粒种子。枯落物覆盖厚度对于种子萌发有显著影响(P<0.05),发芽率、发芽指数、活力指数都随枯落物厚度的增加而增加,平均发芽时间则逐渐降低;但对幼苗生物量、生物量分配和根系特征无显著影响。相关分析表明,苗高和地径与发芽指标、幼苗生物量分配相关性不显著,但与比根长和比根表面积成显著正相关。因此,种子大小和枯落物覆盖厚度是影响沿海黑松防护林天然更新的重要因素。 相似文献
92.
应用从不同林型下分离获得的外生菌根真菌纯培养菌株中的优良菌种,对油松人工林进行菌剂混合接种试验。结果表明:采用外生菌根真菌对油松林接菌,能使土壤微生物种群数量发生变化;接菌后的土壤中的细菌、真菌、放线菌总数比对照有明显的增加,其中真菌增加558.7%。接菌后的油松菌根侵染率为75%,对照为20%;采用外生菌根真菌对油松林接菌,能够提高其抗病力,增强抗旱性,促进林木的生长。对连续2年接种菌剂的油松幼林调查表明,施用菌剂的油松与对照相比,其地径、树高均有显著增加,树高增长46.1%,地径增长41.3%。所以说外生菌根真菌作为一项生物接种技术,对提高油松林的抗病力,增强抗旱性,促进林木的生长具有重要的作用。 相似文献
93.
In this study we determined soil moisture storage, evapotranspiration (ET) and light interception in an agroforestry trial consisting of pine trees grown over (1) control (bare ground), (2) ryegrass/clovers (Lolium perene/Trifolium spp.), (3) lucerne (Medicago sativa), and (4) ryegrass only during the third growing season between 1992 and 1993. The results show that:
相似文献
1. | In the period when rainfall was frequent and exceeded the evaporative demand (Epot), ET and depletion of soil moisture were not affected by the ground cover treatments. During summer when rainfall was less frequent, but with moisture readily available in the soil profile, ET was associated with plant canopy, and was significantly higher for the pasture ground covers than for the control. Therefore, the more rapid growth by lucerne caused higher ET in this ground cover than in the ryegrass/clovers ground cover in which the pasture was slow growing. At the end of the study period, total ET was in the following order: lucerne (757 mm) > ryegrass/clovers (729 mm) > Control (618 mm). |
2. | ET was dominated by pasture transpiration (Ep) during most of the growing season, but by tree transpiration (Et) in winter when large parts of the pasture canopy was shaded. Ep was always at least 16% higher for lucerne than for ryegrass/clovers species as a result of a greater radiation intercepted by the former. |
3. | Fraction of incoming radiation intercepted by the tree crowns was in the following order: control > ryegrass > ryegrass/clovers > lucerne. At the end of the one-year period, fraction of intercepted radiation was 140% greater for control than for lucerne ground cover. |
4. | The control produced the largest tree crowns, which were almost twice the tree crowns in the lucerne ground cover which produced the smallest trees. Accordingly, the trees in the control intercepted more radiation and rainfall, with the former being lost to evaporation, than the trees in the pasture. |
5. | The fractions of radiation intercepted and ET accounted for by the trees and pastures were associated with the proportion of the plot area they occupied. |
94.
小长喙霉 ( Ophiostoma minus Hedgc.)于 190 6年作为新种定名为 Ceratostomella minorHedgc,1981年更名为 Ophiostoma minus Hedgc.,此后一直沿用至今 [1]。小长喙霉以小蠹虫( Tomicus spp.)为媒介 ,通过小蠹虫对树木的蛀害 ,被携带进入到寄主植物组织内 ,进行自身生命过程并危害寄主植物[2 ] ,故也被称为小蠹虫伴生真菌 [3,4] 。该菌的寄主植物主要是松树( Pinus spp.) [4] ,它在协助小蠹虫蛀害松树树木中扮演着重要的角色 [3,4]。80年代以来 ,纵坑切梢小蠹 ( Tomicus piniperda Linnaeus)在云南 8个地州大面积暴发成灾 ,10余万 hm2 … 相似文献
95.
Genetic transformation of loblolly pine using mature zygotic embryo explants by Agrobacterium tumefaciens 总被引:1,自引:0,他引:1
Introduction1Genetictransformationinconifershasthepotentialtoallowtheselectiveimprovementofindividualtraitsinelitecloneswhilestillmaintainingtheexistingcombinationofgenesresponsibleforthesuperiorphenotype(Charestetal.1991;Jamesetal.1996;Walteretal.1999).Atpresent,althoughconsiderableresearchefforthasbeendevotedtothegeneticengineeringofconiferspecies(Sederoffetal.1986;Bekkauoietal.1988,1990;Robertsonetal.1992;Bomminenietal.1993;Shinetal.1994;Klimaszewskaetal.1997),ithaslaggedbehindadvancesma… 相似文献
96.
Dante Arturo Rodríguez-Trejo Mary L. Duryea Timothy L. White Jeff R. English John McGuire 《Forest Ecology and Management》2003,180(1-3):25-36
Nitrogen fertilization in the nursery, along with altering the configuration of forest gaps, may improve the reforestation success of longleaf pine seedlings. During the very droughty 1998 growing season in Florida and Georgia, survival was higher under the forest canopy than in small (0.10 ha, 36 m diameter) and large (1.6 ha, 144 m diameter) canopy gaps. In the large gaps, survival of containerized seedlings was higher along the edges, particularly the SW edge. Shade from adult trees and the nurse effect of shrubs increased survival, while grass competition reduced survival. During dry years part of the “exclusionary zone” along the edge of canopy gaps (SW sector) may serve as a “survival zone”, at least in the short term. A model using oval-shaped gaps oriented from NW to SE, with an area of 0.25 ha is proposed to maximize the survival and growth of artificially regenerated longleaf pine seedlings. 相似文献
97.
Keiji?SakamotoEmail author Naoko?Miki Taiyo?Tsuzuki Takashi?Nishimoto Ken?Yoshikawa 《Journal of Forest Research》2003,8(4):303-309
In pine forests damaged by pine wilt disease, in western Japan, the effect of protection regimes of pine trees on the stand dynamics were examined in the following four stands: (1) lightly damaged stand (age 30–40 years) with no procedure in operation for protecting pine trees; (2) severely damaged stand (age 30–40 years) with no procedure in place for protecting pine trees; (3) severely damaged stand (age 50 years) with a selective cutting of infected trees; (4) severely damaged stand (age 30–40 years) with a selective cutting of infected trees. All the stands had been abandoned before the pine wilt disease damage. The understory structure of the severely damaged stand with no protection procedure was similar to that of the lightly damaged stand. Frequent invasion by tree species and acceleration in the growth of understory trees occurred after the dieback in the selective cutting stand. These results suggest that a deficiency in the canopy layer caused by the dieback resulted in low disturbance intensity in the early stages after the dieback, but the selective cutting increased the intensity by the reduction in the understory as well as the canopy layer. The intensity of the disturbance in the selective cutting stands was larger in the younger stand because it had a higher density of selectively cut pine trees. The different stand structure of pine forests occurred after the dieback because the intensity of the disturbance varied as a result of the selective cutting operation and the stand age. 相似文献
98.
通过对昆明市近郊的长虫山和元宝山林区具有代表性的4片不同龄级的华山松人工林进行了调查,并对不同林龄的华山松人工林的群落结构、物种组成,林下植物生活型、生长型进行了分析。研究结果表明,随着林龄的增长,华山松人工林郁闭度及华山松的株数呈现递减趋势,林下植物的科属种数呈现不同程度的增长趋势,但物种多样性仍然低下,50年龄的华山松人工林分的物种多样性仍然显著低于当地的天然林分;林下植物生长型以灌草为主,其中灌木的重要值随林龄的增长而有所增加,林分结构随林龄增长而趋向稳定。 相似文献
99.
100.