检索结果-南通市图书馆

Optimizing any-aged management of mixed boreal forest under residual basal area constraints

Journal of Forestry Research 2014年第3期25卷 627-636页

作者： Timo Pukkala erkki l?hde Olavi laiho University of Eastern Finland Faculty of Science and ForestryP.O. 111 80101 Joensuu Finland Joen Forest Program Consulting Rauhankatu 41 80100 Joensuu Finland

The current trend of forest management in many countries is reduced use of clear-felling and planting, and increased use of continuous cover management. In Finland, the new forest act of 2014 made all types of cuttings equally allowable on the condition that if the post-cutting residual stand basal area is too low, the stand must be regenerated within certain time frame. Forest landowner can freely choose between even-and uneven-aged management. This study developed a method for opti-mizing the timing and type of cuttings without the need to categorize the management system as either even-aged or uneven-aged. A management system that does not set any requirements on the sequence of post-cutting diameter distributions is called any-aged management. Planting or sow-ing was used when stand basal area fell below the required minimum basal area and the amount of advance regeneration was less than required in the regulations. When the cuttings of 200 stands managed earlier with even-aged silviculture were optimized with the developed system, final felling followed by artificial regeneration was selected for almost 50%of stands. Reduction of the minimum basal area limit greatly decreased the use of artificial regeneration but improved profitability, suggesting that the truly optimal management would be to use natural regeneration in financially mature stands. The optimal type of thinning was high thinning in 97-99%of cases. It was calculated that the minimum basal area re-quirement reduced the mean net present value of the stands by 12-16%when discount rate was 3-5%.

关键词： any-aged silviculture artificial regeneration continuous cover forestry optimal management uneven-aged management

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Stand management optimization——the role of simplifications

引用

Forestry Studies in China 2014年第1期16卷 12-22页

作者： Timo Pukkala erkki lhde Olavi laiho Faculty of Science and Forestry University of Eastern Finland Joen Forest Program Consulting

Background:Studies on optimal stand management often make simplifications or restrict the choice of treatments,Examples of simplifications are neglecting natural regeneration that appears on a plantation site,omitting advance regeneration in simulations,or restricting thinning treatments to low thinning(thinning from below).Methods:This study analyzed the imparts of simplifications on the optimization results for Fennoscandian boreal *** of pine and spruce plantations was optimized by gradually reducing the number of simplifying ***:Forced low thinning,cleaning the plantation from the natural regeneration of mixed species and ignoring advance regeneration all had a major impact on optimization *** thinning(thinning from above) resulted in higher NPV and longer rotation length than thinning from *** was profitable to leave a mixed stand in the tending treatment of young *** advance regeneration was taken into account,it was profitable to increase the number of thinnings and postpone final *** the optimal management,both pine and spruce plantation was gradually converted into uneven-aged mixture of spruce and ***:The results suggest that,with the current management costs and timber price level,it may be profitable to switch to continuous cover management on medium growing sites of Fennoscandian boreal forests.

关键词： Plantation management Continuous cover forestry Even-aged management Mixed stands

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Height increment of understorey Norway spruces under different tree canopies

引用

Forestry Studies in China 2014年第1期16卷 23-30页

作者： Olavi laiho Timo Pukkala erkki lhde1 Joen Forest Program Consulting Faculty of Science and Forestry University of Eastern Finland

Background:Stands having advance regeneration of spruce are logical places to start continuous cover forestry(CCF) in fertile and mesic boreal ***,the development of advance regeneration is poorly ***:This study used regression analysis to model the height increment of spruce understorey as a function of seedling height,site characteristics and canopy ***:An admixture of pine and birch in the main canopy improves the height increment of *** the stand basal area is 20 m2ha-1 height increment is twice as fast under pine and birch canopies,as compared to *** increment of understorey spruce increases with increasing seedling ***-stand and within-stand residual variation in the height increment of understorey spruces is *** increment of 1/6 fastest-growing seedlings is at least 50%greater than the ***:The results of this study help forest managers to regulate the density and species composition of the stand,so as to obtain a sufficient height development of the *** pure and almost pure spruce stands,the stand basal area should be low for a good height increment of the understorey.

关键词： Advance regeneration Continuous cover forestry Growth model Picea abies Uneven-aged management

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

High-sensitivity C-reactive protein in paediatric inflammatory bowel disease

引用

World Journal of Gastroenterology 2010年第23期16卷 2901-2906页

作者： Marianne Sidoroff Riitta Karikoski Taneli Raivio erkki Savilahti Kaija-leena Kolho Division of Gastroenterology and Endocrinology Hospital for Children and AdolescentsUniversity of Helsinki Department of Pathology HUSLABHelsinki University Central Hospital

AIM:To study whether high-sensitivity C-reactive protein(hs-CRP) measurement can aid the assessment of disease activity and glucocorticoid treatment in paediatric inflammatory bowel disease(IBD).METHODS:CRP levels were measured in 39 children with IBD undergoing colonoscopy [median age 12.8 years,Crohn's disease(CD) n=20],in 22 other children with IBD followed for acute response to glucocorticoids,and in 33 paediatric non-IBD *** standard CRP level was below detection limit(l),hs-CRP was ***:Sixty-four percent(25/39) of the children with IBD undergoing colonoscopy displayed undetectable(l) standard CRP *** these,the hs-CRP measurement could not differentiate between active(median,0.2 mg/l,range,0.007-1.37,n=17) or quiescent(0.1 mg/l,0.01-1.89,n=8,P=NS) *** with ileocolonic CD had higher CRP levels(14mg/l,0.06-45,n=13) than patients with no ileal involvement(0.18 mg/l,0.01-9,n=7,Plcerative colitis(UC)(0.13 mg/l,0.007-23,Pldren with active IBD treated with systemic glucocorticoids,the standard CRP was undetectable in 59% of the *** hs-CRP levels did not differ between patients that responded to steroid therapy and in ***:The measurement of hs-CRP did not prove useful in the assessment of disease activity or glucocorticoid treatment in paediatric IBD patients that had undetectable standard CRP.

关键词： C-reactive protein Crohn’s disease Ulcerative colitis Children Inflammatory markers

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

ON lOWNER-ORDERING ANTITONICITY OF MATRIX INVERSION

引用

Acta Mathematicae Applicatae Sinica 1996年第4期12卷 435-442页

作者： erkki P. lISKI(Department of Mathematital Sciences, Universitv of Tampere, Finland) University of Tampere

A new condition for the antitoulcity of the inverse of Herndtian matrices with respect tothe lowner Partial ordering is derived. The basic result is estabhebed by applying directly anelementary formula for a sum of ma... 详细信息

关键词： Hermitian range-Hermitian semidefinite matrices Moors-Penrose inverse,sum of matrices

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Madden-Julian Oscillation-triggered record ozone minimum over the Tibetan Plateau in December 2003 and its association with stratospheric "low-ozone pockets"

A Madden-Julian Oscillation-triggered record ozone minimum o...

引用

“2010年北京气象学会中青年优秀论文评选”学术研讨会

作者： erkki Kyrl Earth Observation Finnish Meteorological InstituteHelsinkiFinland

A record minimum in total column ozone over the Tibetan Plateau in December 2003 is analyzed using both satellite observations and a chemical transport model(MOZART-3). Ozone profiles observed by the MIPAS and GOMOS over the ozone minimum region(25°-35°N,85°-110°E) show pronounced ozone reduction in both the upper troposphere and lower stratosphere(UTlS) and the middle stratosphere ***-3 simulation indicates that ozone reduction in the UTlS region is generally caused by uplift of the local tropopause and northward transport of tropical ozone-poor air associated with an anomalous anticyclone in the upper *** observation suggests that the displacement of "low-ozone pockets" is responsible for ozone decline in the middle-stratospheric region and contributes to 29-46%of the total column ozone *** analysis shows that the upper-tropospheric anticyclonic anomaly is closely associated with the Rossby-wave triggered by the eastward propagating Madden-Julian Oscillation convective heating.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Checking of Radially Sawn Scots Pine and Norway Spruce Wood

引用

Natural Resources 2016年第9期7卷 505-514页

作者： Martti Venäläinen Yonggang Hu erkki Verkasalo Natural Resources Institute Finland (luke) Punkaharju Finland School of Forest Sciences Wood Material Science University of Eastern Finland Joensuu Finland Natural Resources Institute Finland (luke) Joensuu Finland

In exterior use, wood is subjected to weathering that causes checking and other deterioration in the appearance and technical properties. We studied quantitatively the surface checking of radially and tangentially sawn specimens of Scots pine (Pinus sylvestris l.) and Norway spruce (Picea abies Karst.) wood in a cyclic climate chamber test. The results strongly suggested that the sawing direction determines the checking performance of both Scots pine and Norway spruce wood. The radial surface of Scots pine specimens had 62% less checks than the tangential one, and the cumulative area of checks was 74% smaller. For Norway spruce, the respective figures were: 83% less in the check number and 91% less in the check area. Different from pine, in spruce specimens the checks of radial surface were significantly smaller. Thus, spruce timber gained clearly more about radial sawing pattern. The effect of annual ring width was similar for pine and spruce: the reduction in annual growth worsened the checking. The increase in density worsened the checking of spruce but did not change the performance of pine. In pine wood, the increase of heartwood proportion reduced the fluctuation of moisture content and the formation of checks.

关键词： Scots Pine Norway Spruce Checking Sawing Pattern Moisture Content Weathering

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：