尾叶桉MLA无性系林分不同施肥处理经济效益分析

对雷州林业局7种施肥处理的尾叶桉MLA无性系7年生与3年生林分进行经济效益分析，结果表明：最佳处理6(P300g/株 K300g/株 N150g/株)7年生时年均利润1528．1元41m2，比处理7(常规施肥，滤泥5000g/株 P250g/株 K100g/株 N100g/株，年均利润1452．6hm2)提高5．2％，比对照(不施肥，年均利润630．3元/hm^2)提高142．4％；3年生时处理6的年均利润为1605．5元/hm2，比处理7(年均利润1406．8hm2)提高14．1％，比对照(年均利润408．3元/hm2)提高293．2％；处理6的年均利润3年生时采伐比7年生时采伐提高5．1％；处理6和处理7在7年生时采伐，投资回收期均为10．3年，在3年生时采伐分别为8.0年与8．3年，3年生时采伐比7年生时采伐的投资回收期分别缩短2．3年与2．0年。     

Plant biotechnology: A case study ofBacillus thuringiensis (Bt) and its application to the future of genetic engineered trees

Agricultural productivity may be raised in a sustainable way by many different technologies such as biological fertilizers, soil and water conservation, biodiversity conservation, improved pest control, and changes in land ownership and distribution. Of these measures, biotechnology applications probably hold the most promise in augmenting conventional agricultural productivity, because biotechnology applications give not only the need to increase production, but also protect the environment and conserving natural resources for future generations. Biotechnology applications will have the possibilities to increase productivity and food availability through better agronomic performance of new varieties, including resistance to pests; rapid multiplication of disease-free plants; ability to obtain natural plant products using tissue culture; diagnosis of diseases of plants and livestock; manipulation of reproduction methods increasing the efficiency of breeding; and the provision of incentives for greater participation by the private sector through investments. Insect resistance through the transfer of a gene for resistance fromBacillus thuringiensis (Bt) is one of the most advanced biotechnology applications already being commercialized in many parts of the world. This paper reviews the development and the status ofBt technology and application ofBt transgenic plants in current agriculture, and discusses specific issues related to the transfer of the technology to the future of genetic engineered trees with emphasis on conifers. Biography: Tang Wei (1964-), male, Ph. Doctor, Research associate, Department of Biology, Howell Science Complex, East Carelina University, Greenville, NC 27858-4353, USA. Responsible editor: Chal Ruihai     

Difference in cutting age for highest profit by methods for calculating CO<Subscript>2</Subscript> emission trading and the price of CO<Subscript>2</Subscript>

 The amounts of CO₂ that are absorbed and emitted by forest in a model stand area were determined using two calculation methods, namely the flow approach and the stock approach for emission trading, to understand the relationships between the cutting age for the highest profit rate (CAHPR; optimum tree ages to be cut so as to maximize the profit) and (1) the prices of CO₂ and (2) the balance between CO₂ emission and absorption. The resultant CAHPR differed between these two CO₂ accounting methods, which give different tree ages for maximum log volume yield. A rise in CO₂ price caused the CAHPR to approach the tree age of maximum log volume in the flow approach method, and to deviate from the tree age of maximum log volume in the stock approach method. Even at the same CO₂ price, the CAHPR differed between the CO₂ accounting methods. At low CO₂ prices, the CAHPR did not affect situations where the difference of average profit is large by cutting age. On the other hand, the CAHPR was greatly affected at low CO₂ prices when the mean log volume growth changed with tree age. These trends were found to be universal. Received: September 18, 2001 / Accepted: October 25, 2002 Acknowledgments This study is one of the fifth science study subsidy projects of the Japan Forest Technology Association. Correspondence to:K. Sakata     

尾叶桉幼林地上部分生物量及养分循环的研究*

论述了２－３年生尾叶桉幼林地上部分生长、生物量积累和生物量在树木各器官及各径阶中的分配，林分净生产量，树木各器官及凋落物的养分含量和林分的养分循环。２年生时林分的生物量为２２．９ｔ／ｈｍ＾２，其中干材占６０．２％，皮占８．９％，枝占１４．７％，叶占１６．２％。３年生时林分生物量为４０ｔｈｍ＾２，其中干材占６３．６％，皮占７．７％，枝占１４．１％，叶占１４．６％。年净生产量为２０．５ｔ／ｈｍ＾２，约     

The North American long-term soil productivity experiment: Findings from the first decade of research

First decade findings on the impacts of organic matter removal and soil compaction are reported for the 26 oldest installations in the nation-wide network of long-term soil productivity sites. Complete removal of surface organic matter led to declines in soil C concentration to 20 cm depth and to reduced nutrient availability. The effect is attributed mainly to the loss of the forest floor. Soil C storage seemed undiminished, but could be explained by bulk density changes following disturbance and to decomposition inputs of organic C from roots remaining from the harvested forest. Biomass removal during harvesting had no influence on forest growth through 10 years. Soil compaction effects depended upon initial bulk density. Soils with densities greater than 1.4 Mg m⁻³ resisted compaction. Density recovery was slow, particularly on soils with frigid temperature regimes. Forest productivity response to soil compaction depended both on soil texture and the degree of understory competition. Production declined on compacted clay soils, increased on sands, and generally was unaffected if an understory was absent.     

Measuring the productivity and physical workload of brushcutters within the context of a production-based pay system

Forestry occupations are known to be physically demanding, and workers are often paid on a piece rate basis. This pay system is largely used in silvicultural treatments such as plantation and vegetation management. An ill adjusted piece rate system may induce workforce recruitment difficulties or increase accident rates and work related illnesses. A study combining work measurement, ergonomics and economics was undertaken to better understand the factors influencing a worker's workload. Mathematical relations between site factors, worker's production and heart rate variation during work have been examined based on time and motion studies of 38 brushsaw operators performing regeneration release (cleaning) in northern forests. Results show that a piece rate pay system that considers only the area treated without taking into account site factors may lead workers to behave in ways that may compromise their health and safety. The use of a pay system that integrates the influence of site factors on work performance is therefore suggested.     

小议提高用材林森林生产力的途径

通过选用适当的培育方式、遗传改良、林分结构的配置、立地的选择和调控等4个方面的分析论证,论述了寻求提高用材林的森林生产力的途径。     

Storage of biomass and net primary productivity in desert shrubland of Artemisia ordosica on Ordos Plateau of Inner Mongolia, China

Biomass and net primary productivity （NPP） are two important parameters in determining ecosystem carbon pool and carbon sequestration. The biomass storage and NPP in desert shrubland of Artemisia ordosica on Ordos Plateau were investigated with method of harvesting standard size shrub in the growing season （June-October） of 2006. Results indicated that above- and belowground biomass of the same size shrubs showed no significant variation in the growing season （p〉0.1）, but annual biomass varied significantly （p〈 0.01）. In the A. ordosica community, shrub biomass storage was 699.76-1246.40 g.m^-2 and annual aboveground NPP was 224.09 g-m^-2·a^-1. Moreover, shrub biomass and NPP were closely related with shrub dimensions （cover and height） and could be well predicted by shrub volume using power regression.     

Biomass and net productivity for spruce plantation

SiteandmethodThesiteislocatedintheSuiIingDistrictofHeiIong-jiangProvincefromN47"26'toN48"o6',E127"37'toE128"28'.TheaveragesIopeis15".Themeanelevationis349m.ThemeanannuaItem-peratureis-o.4t.TheaccumuIatedtemperatureof31ooCis1986C-Theamountofprecipitationisfrom6ooto8oomm.Thefrost-freeseasonisabout13od.ThemainsoilisdarkbrownsoiI.The17plots(o.o4hm')fordifferentages,differ-entsitesweremeasured.OnesampletreewasseIectedineverypIot,ThefalIenstemanalysistreesweredividedwithonemeterortwometer…     

Quantification and Understanding of Above and Belowground Biomass in Medium Saline Zone of the Sundarbans,Bangladesh: The Relationships with Forest Attributes

ABSTRACT

The relationship between stand attributes and biomass accumulation pattern in a mangrove forest has been intensively studied in this study. We assessed above (AGM) and belowground mass (BGM) and examined the relationship between forest attributes and aboveground mass in the Sundarbans, Bangladesh. The study was conducted with 18 plots having total area of 1.08 ha. The mean AGM and BGM of the study sites were 234.08 and 132.85 Mg ha^?1 respectively. H. fomes contributed the highest amount (82.9% of total AGM and 80.53% of total BGM) of above (193.56 Mg ha^?1) and belowground mass (107.09 Mg ha^?1) at the study site. Our study revealed structural attributes (tree diameter, height, and basal area) positively correlated with AGM. In contrast, species richness and species diversity negatively correlated with AGM. Our study indicated that lack of positive relationship between species diversity and AGM which may be attributable to high AGM of the dominant species (H. fomes) and may have a considerable consequence in AGM of the study area. Thus, maintaining large trees (DBH and height) rather than species diversity in the Sundarbans mangrove forest might be an effective approach for increasing aboveground mass.