中东海枣苗圃地化学除草试验

在使用多种除草剂初步试验的基础上,采用10%草甘膦水剂进行随机区组排列试验,结果表明:10%草甘膦水剂能有效防除苗圃地一年生杂草,剂量为1.95ml·m-2时,防除阔叶杂草效果达97.5%,剂量为2.25ml·m-2时,防除窄叶杂草的效果达90.9%。10%草甘膦水剂不同剂量之间防除杂草效果的差异极显著,防除阔叶、窄叶杂草的防除效果之间的差异极显著。以2.25ml·m-2的剂量计,化学除草成本为0.01元·m-2,与人工除草相比,该化学除草成本是人工挖草的7.2%,人工铲草的23.8%。为保护好苗木,在喷除草剂时应做好幼苗的套袋保护工作,并根据杂草大小等情况适当调整剂量,从而达到理想的剂量与成本组合。     

30%飞达草甘膦可溶性粉剂防除苗圃杂草试验

分析了在苗圃地使用30％飞达草甘膦可溶性粉剂防除杂草试验,结果表明：使用30％飞达草甘膦可溶性粉剂的最佳剂量丁香苗圃地为3．0kg／hm^2,除草效果可达到80％以上;青海云杉和祁连圆柏苗圃地为3．7kg／hm^2以上,除草效果可达到70％以上。河西地区使用30％飞达草甘膦可溶性粉剂防除苗圃杂草,全年施药2～3次即可达到理想效果。施药除草必须严格按照操作规程进行,以取得最大防除效果,并避免发生药害。     

“快招”等3种除草剂在针叶树育苗上的应用试验

应用10%草甘膦水剂、快招(41%草甘膦异丙胺盐水剂)、20%克无踪水剂等3种除草剂对青海云杉苗圃地开展了除草试验。结果表明:3种除草剂中以"快招"效果最好,浓度以10 mg·g-1为宜。在晴朗无风的中午,采取定向喷雾,对青海云杉苗圃地杂草有较好的防除效果;和人工除草相比较,使用"快招"除草可节省费用73.3%。     

香榧苗圃地除草剂筛选试验

为提高香榧苗圃地杂草的防除效果,保护苗木,降低用工成本,选用普通市售除草剂,采用随机区组和正交设计筛选对香榧苗木无害且有效的除草荆单荆和组合.结果表明:(1)推荐剂量范围内不同除草剂对香榧苗圃地杂草都有一定的防除效果,药后第28天的株防效在57.46%～74.63%之间.果尔、百草枯的株防效较好,时效较长,可以选用;草甘膦的短时株防效最高,但时效短;精稳杀得起效较慢.(2)不同浓度除草剂混用后的除草效果比单剂好,药后第28天的株防效在84.32%～94.74%,筛选出的24%果尔乳油(1 050 mL/hm2)+10%草甘膦水剂(16 500 mL/hm2)+15%精稳杀得乳油(450 mL/hm2)复配剂除草效果最佳.(3)香榧苗圃地使用除草剂对苗木生长无影响,而且工效高,伤苗少,成本低,相对人工除草降低1 950 元/hm2以上.     

草甘膦和调节膦混用在非耕地上除草效果

本研究表明 ,4 0 %调节膦水剂 +65 %草甘膦可溶性粉剂组成的双膦混剂 ,在非耕地上进行化学除草 ,每 667m2 用有效量为 60g +60g ,对水 5 0kg ,除草效果达 91% ,而单用 4 0 %调草膦水剂 ,每 667m2 用有效量 140g ,除草效果为 75 % ;单用 65 %草甘膦可湿性粉剂 ,每 667m2 用有效量 130g除草效果为84 % ,混用比单用好。值得在林区推广应用     

草甘膦和调节膦混用在非耕地上除草效果

本研究表明，40%调节膦水剂 65%草甘膦可溶性粉剂组成的双膦混剂，在非耕地上进行化学除草，每667m^2用有效量为60g 60g，对水50kg，除草效果达91%，而单用40%调草膦水剂，每667m^2用有效量140g，除草效果为75%；单用65%草甘膦可湿性粉剂，每667m^2用有效量130g除草效果为84%，混用比单用好。值得在林区推广应用。     

草甘膦除草剂在幼林地除草试验初报

应用 10 %草甘膦水剂进行杉阔混交幼林地除草试验表明 :除草效果在一定程度上随着草甘膦浓度的增大而提高 ,一般 6 6 7m2 施用 10 %草甘膦 1 5kg便可达到除草目的 ;草甘膦对白茅、山麻及大部分禾本科杂草有较好的杀除作用 ,对小刚竹、白背叶、多年生灌木杀除效果不很明显     

苗圃大苗地化学除草技术研究

苗圃地除草是一项繁重的工作,长期以来多用人工除草,费时费工成本高。石河子林业站在苗木基地应用“农达”41％水剂,10％草甘膦水剂,24％“杀草狂”乳剂等3种除草剂进行对比试验,效果显著,其中“农达”使用方便,成本低,效果较好,可大面积推广。     

刺槐迹地更新仁用杏树草甘膦除草试验

应用草甘膦对刺槐迹地更新仁用杏树杀灭杂草和刺槐萌蘖,杂草幼苗期每667 m2使用100~300 g纯剂量草甘膦加50 kg清水喷洒杀灭达89.0%~97.5%;春季刺槐萌芽期用3%草甘膦水剂涂抹树桩加生长季节喷洒0.4%草甘膦水剂3次,或在刺槐生长季连续2年喷洒200~300 g/667m2草甘膦水剂,刺槐树桩杀灭80%以上。多年应用未出现药害,仁用杏幼树生长量和杏核累计产量较人工除草地降低不明显。应用草甘膦除草、杀灭刺槐树桩效果好,对仁用杏幼树生长结果安全。     

4种除草剂在紫薇苗圃中的试验研究

采用24%乙氧氟草醚乳油、96%精异丙甲草胺乳油、41%草甘膦水剂、20%百草枯水剂4种除草试剂,在紫薇苗圃中进行了除草效果试验,结果表明:(1)4种除草单剂中乙氧氟草醚的除草效果最好;(2)不同浓度除草剂混用后的除草效果比单剂好,其中23.5%乙氧氟草醚乳油(1 245mL/hm2)+96%精异丙甲草胺乳油1 275mL/hm2)复配剂除草效果最佳;(3)紫薇苗圃地使用除草剂对苗木生长影响小,而且工效高,伤苗少,成本低,相对人工除草降低2 500元/hm2左右。     

Long-term response of weed control intensity on Scots pine survival, growth and nutrition on former arable land

The effects of post-planting weed control intensity on the cover and composition of ground vegetation, and on growth, survival and foliar nutrient concentrations of 4-year old bare-rooted Scots pine (Pinus sylvestris L.) seedlings were studied over a 15-year period with experimentation on former arable land. Weed control treatments with terbuthylazine and glyphosate were carried out 1?C3 times during successive years, either as overall or as spot applications. The vegetation cover and the shading effect of vegetation decreased with increasing weed control intensity. The more intensive the weed control was, the better was the afforestation result in terms of tree seedling growth and survival. Overall application repeated three times increased seedling survival by 79 percentage points, and their final height, breast height, diameter, and stand volume after 15 years were increased by 183, 19, 15, and 822%, respectively. Weed control did not affect the foliage nutrient concentrations, except for magnesium. However, increase in weed control intensity was reflected in larger needle size 5 years after planting.     

Role of weeds in the management of nitrogen in a young Pinus radiata plantation

Pinus radiata trees were grown on a podzolized sandy soil at a second rotation site under the following treatments: total weed control, total weed control plus ammonium nitrate, strip weed control and no weed control. During the first two summers after planting the differences in needle water potential between trees under no, strip or total weed control were very small. Despite similar rates of net N-mineralization in strip and total weed control treatments, which averaged 64 kg ha^–1 yr^–1 in the 0–15 cm soil depth, weeds in the strip weed control treatment reduced soil mineral-N concentrations by 50–80%, leaching of N by the end of the first growing season by 45%, foliar-N concentrations by 4–14% and stem biomass at 20 months after planting by 46%. Although N-uptake by above-ground vegetation (trees plus weeds) was 49% higher in the strip weed control treatment, the amount of N apportioned to trees during the first 20 months after planting was reduced from 15.5 to 9.0 kg ha^–1. These effects of weeds were even more pronounced in the no weed control treatment. Since weeds had little effect on the needle water potential of trees and the annual rates of N-mineralization, but adversely affected N-uptake by trees, results indicate that weeds directly competed with trees for N, and thereby aggravated N-deficiency in trees. Application of ammonium nitrate after complete weed control increased foliar-N concentrations, and N-uptake and growth of trees, but also induced severe stem deformation.     

Herbaceous weed control in conifer plantations with hexazinone and nitrogen formulations

In order to determine if herbicide efficacy is affected by nitrogen fertilizer, the influence of different nitrogen fertilizers applied in different combinations with hexazinone formulations were evaluated on herbaceous weed communities. Field studies comparing three application methods in conifer plantations showed greatest reduction in total weed cover with a co-granular formulation of hexazinone and triamino-s-triazine. Slightly less control was achieved with separate applications of liquid hexazinone and triamino-s-triazine granules, and poorest control with granular urea followed by liquid hexazinone. Weed control increased with an increase in hexazinone rate. Statistical analysis of the effect on conifers showed that the highest hexazinone rate significantly increased survival of noble fir (Abies procera Rehd.) and stem diameter of both noble fir and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and that the highest nitrogen rate significantly decreased survival of both species but did not affect stem diameter. Survival of noble fir and diameter of both noble fir and Douglas-fir were significantly increased where a co-granular formulation of hexazinone and triamino-s-triazine granules was used.     

Herbicides are more cost-effective than alternative weed control methods for increasing early growth of Eucalyptus dunnii and Eucalyptus saligna

Effective weed control is an essential management task in establishing commercial tree plantations. Much of the current weed control strategies employed in Australian forestry relies on the use of available herbicides. However, given community concern regarding the use of herbicides, investigation of alternative weed control methods is warranted. We tested the ability and cost-effectiveness of mechanical (hand weeding and inter-row slashing), mulching (sawdust over newsprint, woodchips and jute), cover crops and herbicide applications for weed control in establishing eucalypt plantations. Jute matting and herbicide treatments reduced weed competition and increased seedling growth to age 2 years in plantations of Eucalyptus dunnii and Eucalyptus saligna in northern NSW, Australia. Growth increased by 269 % (Experiment 1) and 196 % (Experiment 2) in the Jute and by 216 % (Experiment 2) in the Herbicide treatments when compared to the control (no weed control) at 2 years age. As the Jute material deteriorated, after nearly 2 years, weed cover increased and there were significantly more weeds present in the Jute treatment compared to the Herbicide treatment. Jute matting costs approximately 15 times more than the herbicide regime used and, therefore, could not presently be considered a viable option for weed control in commercial eucalypt plantations. Other weed control treatments, including hand weeding, sawdust and woodchip mulches, slashing and sowing cover crops did not effectively control weeds and did not improve survival or increase seedling growth to age 2 relative to the control. We conclude that herbicides remain the most cost-effective weed control option available to commercial growers of eucalypt plantations.     

3-level MCGP: an efficient algorithm for MCGP in solving multi-forest management problems

The efficiency gains when harvests are determined using the Faustmann approach instead of Maximum Sustained Yield (MSY), Forest Rent or some silvicultural rules were studies. The analysis was based on a variable-density stand growth model and computations over all admissible combinations of initial stand age and basal area for Finnish Norway spruce and Scots pine sites. Following MSY or Forest Rent led to a major reduction in the economic value of especially highly stocked stands. Finnish silvicultural recommendations (an example of silvicultural rules) encouraged production of higher than optimal quality timber. Applying Forest Rent, MSY or silvicultural recommendations led to respective reductions of 63%, 30% and 13% in the value of a typical conifer forest at a 4% rate of interest. The results also showed that an increase in the rate of interest may lengthen the ongoing rotation if the initial state falls outside the optimal path initiated at bare land.     

Effects of application date and rate of foliar-applied glyphosate on pine seedlings in Turkey

Glyphosate is the herbicide most extensively used for site preparation and conifer release. It is a broadspectrum herbicide and therefore crop safety is a critical issue. This study assessed the early effects of 14 different treatments, including no weed control, manual weed control, and 12 foliar-applied herbicide treatments at low,intermediate, high, and highest application rates and application timing on glyphosate phytotoxicity of containerized seedlings of Austrian pine(Pinus nigra J.F.Arnold.), Scots pine(P. sylvestris L.) and maritime pine(P.pinaster Aiton), conifer species widely used for afforestation and supplementary plantings in Turkish forestry. In general, Scots pine seedlings were tolerant to glyphosate compared to the other species. Glyphosate phytotoxicity varied significantly according to the time and rate of application. Seedlings were relatively tolerant to glyphosate in April whereas they were intolerant in May. The highest herbicide rate(1.2% v:v) was consistently phytotoxic to all species. Moreover, the effect of herbicide rate on seedling survival and growth varied significantly according to application date(i.e., application rate 9 date interaction). Seedlings appeared tolerant to glyphosate at low and intermediate rates(0.2, 0.4% v:v) between midspring and mid-summer, whereas they demonstrated significant sensitivity to the highest rate across all time periods. Glyphosate at the high rate(0.8% v:v) was particularly more phytotoxic when applied in May. Application of glyphosate at rates up to 0.8% could be recommended for weed control without significant pine damage in midspring when the needles presumably have a dense leaf epicuticular wax layer limiting herbicide penetration.Applications of 0.8 and 1.2% v:v are not recommended during May–June.     

Forest cover changes in the Oregon Coast Range from 1939 to 1993

Understanding the shifts over time in the distribution and amount of forest vegetation types in relation to forest management and environmental conditions is critical for many policy and ecological questions. Our objective was to assess the influences of ownership and environment on changes in forest vegetation from post-settlement historical to recent times in the central Coast Range of Oregon. We evaluated land cover types on 1475 20 m plots, using scanned, geo-referenced historical (1939) and recent (1993) aerial photos. The amount of older conifer cover declined by 63% relative to its former amount, from 36 to 13% of the landscape, during the 54-year period. Dominant ownership of older conifer stands shifted from industrial private to Forest Service lands. Younger conifer stands showed the greatest expansion in cover, increasing more than two-fold, from 21 to 44% of the landscape. Shrub and hardwood cover declined by 16%, from 31 to 25% of the landscape. Shrubs and hardwoods occurred at lower slope positions and closer to streams at the end of the period than at the beginning. Ownership was not an important determinant of the presence of large and very large conifer cover or shrub and hardwood cover in 1939, but was a very important factor affecting the presence of these cover types in 1993. Landscape transitional pathways were distributed among many types and no single transitional pathway was dominant. Even the most stable cover types (hardwood trees and herbs) had low absolute stability, with over 65% of their plots changing to another cover type by 1993. Our research indicates that the importance of ownership as a factor affecting the type of vegetation cover present has increased greatly during this time, whereas the relative influence of environment has lessened considerably. Land owners in the Oregon Coast Range have altered the cover and distribution of vegetation in diverse ways, changing the landscape to one dominated by young conifers, shifting the distribution of younger successional shrubs and hardwoods toward streams, and restricting the location of older coniferous stands to particular ownerships and site types.     

Effects of changes in land use and land cover on sediment discharge of runoff in a typical watershed in the hill and gully loess region of northwest China

Land use plays a much more important role than other factors, such as climate, soil properties, topographic features, vegetation coverage, human activities and others, in affecting soil erosion and sediment discharge. In order to understand the effects of changes in land use on sediment discharge and to provide a theoretical basis for land use planning, management and ecological restoration, we used the controlled Qiaozidong watershed and the uncontrolled Qiaozixi watershed in the third sub-region of the Loess Plateau as examples and analyzed the effects of land use and land cover on the discharge of sediments. The results show that the impact of land use and land cover on the annual amount of sediment discharge is significant. Compared with the uncontrolled watershed during similar periods, the amount of sediment discharged from the controlled watershed was reduced by 44%, 75% and 86%, respectively, in wet, normal and dry years. In the controlled watershed, compared with the period from 1986 to 1994, the amount of sediments discharged was less during the period from 1995 to 2004. The impact of land use and land cover on sediment discharge demonstrated characteristics of seasonal fluctuation. The effects of sediment reduction in the controlled watershed were greater than those in the uncontrolled watershed in May and September. In the controlled watershed, the reduction effect coincided with the distribution of rainfall. The amount of discharged flood sediments is closely correlated with rainfall, rainfall intensity in a 60 min period and the volume of flood. The rainstorm-runoff process and the rainstorm-sediment discharge process demonstrate that land cover has a strong regulatory and control function in the flood process and sediment discharge in rainstorms. For the controlled watershed, given the same precipitation frequency distribution, the average amount of sediment discharged during the land use period from 1995 to 2004 was less than that during the earlier land use period from 1986 to 1994 under every recurrent period. __________ Translated from Journal of Beijing Forestry University, 2007, 29(6): 115–122 [译自: 北京林业大学学报]     

Effect of early age woody and herbaceous competition control on wood properties of loblolly pine

Early age competition control has been reported to significantly improve the growth and yield of plantation grown loblolly pine. The objective of this paper is to understand the changes in wood properties: basal area weighted whole disk SG, earlywood SG (EWSG), latewood SG (LWSG) and latewood percent (LWP) of 14 year-old trees which received early age herbaceous and hardwood competition control, using data collected from 13-sites across 4-physiographic regions in the southeastern USA. The study was laid out in a randomized complete block design and had four levels of weed control (no weed control; woody vegetation control; herbaceous vegetation control; and woody and herbaceous vegetation control), with four blocks at each site. Increment cores 12 mm in diameter were collected at breast height (1.37 m) from 9-trees in each plot and ring-by-ring SG, EWSG, LWSG and LWP measured using a X-ray densitometer. Whole disk basal area weighted SG and LWP were determined for each tree and used for analysis. A reduction in whole disk SG of 0.039 and 0.0014 and LWP of 7.38% and 3.62% was observed for trees which received total weed control compared to no weed control, for lower and upper Coastal Plain sites, respectively. For trees receiving total weed control compared to no weed control, it was observed that the diameter of the juvenile core increased by 20% on average across all physiographic regions. However, no change in the length of the juvenile period was observed among treatments other than the regional differences.     

山东省针叶树(球果类)引种驯化及评价

树木的引种驯化是增加林木种质资源的一种传统育种方法。山东省有记载的针叶树引种历史应追溯到19世纪末至20世纪初,在20世纪50年代和70年代分别出现两个引种高峰期,分别占引种种质的26.5%和21.5%。山东有计划的科学引种针叶树种约30个,其中银杏科1个属1个种,19份种质;松科5个属39份种质;杉科4个属5份种质;柏科3个属3个种质,共计66份种质,其中松科种质占总引种种质59.09%,而松属种质占松科种质79.49%。从1978~2006年省林业厅鉴定或获奖的项目中针叶树遗传改良占4.77%,审(认)定品种占总数量5.22%。建议:(1)强化针叶树引种驯化策略;(2)明确引种驯化程序、标准和关键技术;引种驯化与种质创新相结合;(3)重视乡土树种驯化及开发。本文对针叶树引种驯化与遗传改良进行了评价。