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Two decades of variable retention in British Columbia: a review of its implementation and effectiveness for biodiversity conservation

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Ecological Processes 2019年第1期8卷 402-423页

作者： William J.Beese John Deal B.Glen Dunsworth Stephen J.Mitchell Timothy J.Philpott Vancouver Island University 900 Fifth StreetNanaimoBC V9R 5S5Canada Western Forest Products 118–1334 Island Hwy.Campbell RiverBC V9W 8C9Canada Glen Dunsworth Ecological Consulting 7857 Shangri-La Rd.LantzvilleBC V0R 2H0Canada University of British Columbia 2424 Main MallVancouverBC V6T 1Z4Canada bc min.of forests Lands and Nat.Res.Oper400–640 Borland St.Williams LakeBC V2G 4T1Canada

Stand-level retention is an important component of sustainable forest management which aims to balance ecological,social and economic ***-term retention of mature forest structures at the time of harvesting(variable retention)is intended to produce future forest stands that more closely resemble conditions that develop after natural disturbances,thereby maintaining greater diversity of habitats for a variety of *** includes features such as live and dead trees representing multiple canopy layers,undisturbed understory vegetation and coarse woody *** the past two decades,variable retention has become common on forest lands in the temperate rainforests of coastal British Columbia(bc)and has been applied to a lesser extent in inland forest *** review of studies in bc and in similar forest types in our region indicates that both aggregated and dispersed retention can contribute to biodiversity conservation by providing short-term‘life-boating’habitat for some species and by enhancing the structural characteristics of future *** example,greater abundance of species present in the pre-harvest forest have been documented for vegetation,birds,carabid beetles,gastropods,ectomycorrhizal fungi and soil fauna in retention cutblocks compared to *** are,however,some negative consequences for timber production such as wind damage to retained trees and reduced growth rates of tree regeneration compared to *** authors suggest an adaptive management approach for balancing competing objectives when faced with *** includes monitoring the implementation and effectiveness of various strategies for achieving *** two decades of experience applying variable retention harvesting to industrial-scale management of forest lands in bc suggests that it is possible to balance production of wood with biodiversity conservation.

关键词： Alternative silvicultural systems Clearcutting Biological legacies Forest biodiversity Old-growth Variable retention British Columbia

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Microstructure,Tensile and Impact Toughness Properties of Friction Stir Welded Mild Steel

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Journal of Iron and Steel Research(International) 2010年第10期17卷 68-74页

作者： A K Lakshminarayanan V Balasubramanian M Salahuddin Department of Manufacturing Engineering Annamalai University Clean Technology Division Ministry of Environment and Forests

Microstructure, tensile and impact toughness properties and fracture location of friction stir welded AISI 1018 mild steel were revealed. The AISI 1018 mild steel plates with thickness of 5 mm were friction stir welded by tungsten based alloy tool with tool rotational speed of 1 000 r/min and welding speed of 50 ram/rain. Tensile strength of stir zone is higher （8%） compared to that of the base metal. This may be due to the formation of finer grains in the weld nugget region under the stirring action of the rotating tool. The ductility and impact toughness of the joints are decreased compared to those of the base metal owing to the inclusion of tungsten particles in the weld region.

关键词： friction stir welding tensile property impact toughness mildsteel

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不同植被类型的土壤水分对黄土高原的影响(英文)

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Journal of Geographical Sciences 2009年第6期19卷 707-718页

作者：王志强刘宝元张岩 State Key Laboratory of Earth Surface Processes and Resource Ecology School of Geography Beijing Normal University Key Laboratory of Soil and Water Conservation & Desertification Combat Beijing Forestry University Min-istry of Education

Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau,but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth. The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter-annual change. Soil moisture in 0-10 m depth of six vegetation types,i.e.,crop,grass,planted shrub of caragana,planted forests of arborvitae,pine and the mixture of pine and arborvitae were measured in 2001,2005 and 2006. Soil moisture in about 0-3 m of cropland and about 0-2 m of other vegetation types varied inter-annually dependent on annual precipitation,but was stable inter-annually below these depths. In 0-2 m,soil moisture of cropland was significantly greater than those of all other vegetation types,and there were no significant differences among other vegetation types. In 2-10 m,there was no significant moisture difference between cropland and grassland,but the soil moistures under both of them were significantly higher than those of planted shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point,and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly lower than those of forests,but the absolute difference was very small. The results of this study implicated that the planted shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on present year precipitation for transpiration.

关键词：植被类型黄土高原土壤水分

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Relationships between native tree species and soil properties in the indigenous forest fragments of the Eastern Arc Mountains of the Taita Hills, Kenya

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Forestry Studies in China 2011年第3期13卷 198-210页

作者： Loice Mildred Akinyi OMORO Raija LAIHO Michael STARR Petri K.E.PELLIKKA Viikki Tropical Resources Institute Department of Forest Sciences University of HelsinkiP.O.Box 27 (Latokartononkaari 7) Helsinki FIN-00014 Finland Department of Forest Sciences University of HelsinkiP.O.Box 27 (Latokartanonkaari 7) Helsinki FI-00014 Finland Department of Geography University of HelsinkiP.O.Box 64 (Gustaf H llstr min katu 2) Helsinki FI-00014 Finland

The relationship between soil properties and spatial distribution of native woody species was studied in three Taita Hills forest fragments which, although degraded, are ranked among 34 biodiversity hotspots of the world due to their high biodiversity of both plant and animal species. This relationship was assessed by using Spearman correlation and principal component analyses （PCA）. The results of these analyses should be useful in instituting forest restoration programs that are crucial for the forests. Both the soil and vegetation studied were sampled from 17 subplots in the natural forest fragments of Ngangao （120 ha）, Chawia （86 ha） and Mbololo （185 ha）. The soil variables measured were： pH, texture, soil nutrients of C, N, Ca, P, K, Mg and Na. In total 36 native tree species from 13 families were identified from the three forest fragments. Ordination results show that axis 1 accounted for 35% and axis 2 for 25% of the total variation in species composition, indicating that the structure of vegetation is related to two major environmental gradients. The correlation analyses of species and soil properties showed that Na and clay particles were the most important determinants of species distribution; pH and soil variables such as C, N, Ca and P also played minor roles. Unexpectedly, some species （e.g. Psychotria petitii） showed positive relationships with Na attributed to possible substitution for K. Relationships with P were both positive （e.g. Craibia zimmermannii） and negative （e.g. Albizia gummifera） with some species, attributable to pH levels. An ANOVA for soil variables showed that there were differences in the Ca content in Mbololo （due to the parent material） and P in Ngangao where a special relationship was observed between some of the species. The presence of gaps accounted for the distribution of seedlings but not for the saplings, whose distribution responded more to factors similar to those to which mature trees respond. Soil-species relationships

关键词： Eastern Arc Mountains forests principal component analysis soil variables native woody species

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