Multi-purpose forests on peatland

Current forestry policy has multiple objectives including wood production, nature conservation, landscape, recreation and environment protection. There are about 190 000 ha of planted forest on deep peat and another 315 000 ha on shallower peat. Deep peat covers just over 2 million ha in Britain, so the area planted is some 9.5%. The paper describes how modern silvicultural practices are designed to achieve these multiple benefits of forests on peatland.     

Dominance of legume trees alters nutrient relations in mixed species forest restoration plantings within seven years

Failures in reforestation are often attributed to nutrient limitation for tree growth. We compared tree performance and nitrogen and phosphorus relations in adjacent mixed-species plantings of contrasting composition, established for forest restoration on Ultisol soil, originally covered by tropical semi-deciduous Atlantic Forest in Southeast Brazil. Nutrient relations of four tree species occurring in both planting mixtures were compared between a legume-dominated, species-poor direct seeding mixture of early-successional species (“legume mixture”), and a species-diverse, legume-poor mixture of all successional groups (“diverse mixture”). After 7 years, the legume mixture had 6-fold higher abundance of N₂-fixing trees, 177% higher total tree basal area, 22% lower litter C/N, six-fold higher in situ soil resin-nitrate, and 40% lower in situ soil resin-P, compared to the diverse mixture. In the legume mixture, non-N₂-fixing legume Schizolobium parahyba (Fabaceae-Caesalpinioideae) had significantly lower proportional N resorption, and both naturally regenerating non-legume trees had significantly higher leaf N concentrations, and higher proportional P resorption, than in the diverse mixture. This demonstrate forms of plastic adjustment in all three non-N₂-fixing species to diverged nutrient relations between mixtures. By contrast, leaf nutrient relations in N₂-fixing Enterolobium contortisiliquum (Fabaceae-Mimosoideae) did not respond to planting mixtures. Rapid N accumulation in the legume mixture caused excess soil nitrification over nitrate immobilization and tighter P recycling compared with the diverse mixture. The legume mixture succeeded in accelerating tree growth and canopy closure, but may imply periods of N losses and possibly P limitation. Incorporation of species with efficient nitrate uptake and P mobilization from resistant soil pools offers potential to optimize these tradeoffs.     

中国人工林经营发展战略与对策:从追求木材产量的单一目标经营转向提升生态系统服务质量和效益的多目标经营

人工林是全球森林资源的重要组成部分,在木材生产、环境改善、景观建设和减缓气候变化等方面扮演着愈来愈重要的角色。尽管我国人工林面积和蓄积不断增长,但是,人工林存在质量较差、结构不尽合理、生产力不高、生态功能较弱和生态稳定性下降等问题。人工林生态系统服务功能难以满足经济社会日益增长和新时期人们对美好生活向往的多方面需求。面对未来人工林面积继续增加受到适宜发展空间的严重制约和气候变化带来的现实和潜在的影响,亟需改变和调整我国人工林经营的发展战略和对策,将从人工林面积扩张、蓄积增加转变为人工林生态系统服务的质量和效益提升。如何提高人工林生态系统服务的质量和效益,创建健康稳定、高生产力和高碳汇的人工林生态系统,既能提供高产优质木材,又能够发挥固碳减排、生物多样性保护、水源涵养和水土保持等多种生态功能,以满足经济社会发展对森林的多种新需求和林业应对气候变化的新任务,亟需探索适合我国新时期人工林生态系统可持续经营的理论和多目标经营范式。在深入分析国际和我国人工林发展历程、变化趋势、面临问题的基础上,充分汲取和借鉴国际人工林经营的理念、经验和实践成果,并结合我国现阶段人工林发展实际情况,探索人工林生态系统服务质量与效益提升的发展思路和实践途径,从多层次、多尺度定位面向生态系统服务的人工林经营对策,倡导并实施人工林生态系统适应性经营,实现人工林生态系统服务的多目标权衡与协同,为我国人工林经营的战略转变和对策创新提供决策参考与未来展望。     

A multi-purpose modular limnological sampler

This paper describes a new type of multi-purpose limnological sampler, based on several modules which, when fitted together in various ways, and with accessory items, can be used to sample in many different fashions. The main advantages of the sampler are that, in addition to its ability to perform a variety of functions, it is both cheap and light. It is particularly suitable for multi-purpose work on remote waters to which transport of heavy or bulky equipment is difficult or expensive. The complete package described, best operated by two people, currently costs £ 75 and weighs 20 kg. It enables the operators to sample several aspects of water, sediments, phytoplankton, macrophytes, zooplankton, zoobenthos and fish in several ways, both qualitatively and quantitatively, from a boat or from the shore.