生物技术在林业中的应用及其影响

现代生物技术正在被越来越多地应用到林业研究和生产中,并将对林业的发展产生深远的影响。本文总结了目前在林业中应用和正在发展的生物技术,探讨了与使用这些技术有关的主要问题及争论,强调了科学地评价这些技术,以及在社会可接受的范围内进行决策的重要性。最后,本文简要指出了将来生物技术研究和应用的方向,并说明了政府应该在何种程度上帮助生物技术的发展及调节它的应用。     

Underplanting degraded exotic Pinus with indigenous conifers assists forest restoration

We propose that nonharvest plantations could provide important opportunities for restoration of indigenous forest cover and related ecosystem services. We assessed the relative performance of three Podocarpaceae (podocarps) species planted into a degraded Ponderosa Pine (Pinus ponderosa) plantation, central North Island, New Zealand. We hypothesised that the degraded pine plantation overstorey could provide suitable conditions for the development of a podocarp‐dominated forest structure within ca. 50 years of underplanting and that podocarp growth would differ depending on the species suitability to the site. Rimu (Dacrydium cupressinum) significantly outperformed both Totara (Podocarpus totara) and Kahikatea (Dacrycarpus dacrydioides) in height and diameter growth. Rimu was now the structurally dominant tree where it occurred rather than pine. Per annum scaled carbon storage within Rimu stands was significantly greater than the Totara, Kahikatea or Pine stands. All podocarp species had attained a greater stand density compared to the pine overstorey. Possible reasons for the differing podocarp growth performance include different light requirements, response to soil nutrients, elevational distributions and frost susceptibility. There were significant differences in understorey species richness among the different stands of podocarp species. Underplanting accelerated successional development by incorporating late‐successional indigenous canopy dominants within the forest succession and overcame limitations imposed on forest succession at the site from its isolation from indigenous forest tree seed sources.     

Decomposition and Peat Accumulation in Rich Fens of Boreal Alberta, Canada

Fens are important components of Canada’s western boreal forests, occupying about 63% of the total peatland area and storing about 65% of the peatland carbon. Rich fens, dominated by true moss-dominated ground layers, make up more than half of the fens in the region. We studied organic matter accumulation in three rich fens that represent the diversity in structural types. We used in situ decomposition socks, a new method that examines actual decomposition throughout the upper peat profile over an extended period of time. We coupled our carbon loss data with macrofossil analyses and dated peat profiles using ²¹⁰Pb. Across the three rich fens and in the top 39 cm of the peat column, dry mass increases on average 3.1 times. From our dry mass loss measurements, we calculate that annual mass loss from the top 39 cm varies from 0.52 to 1.08 kg m². Vertical accumulation during the past 50 years has varied from 16 to 32 cm and during these 50 years, organic matter accumulation has averaged 174 g m⁻² y⁻¹ compared to 527 g m² y⁻¹ dry mass loss, with additional mass losses of 306 g m² y⁻¹ from peat between 50 and 150 years of age. Organic matter accumulation from our rich fens compares well with literature values from boreal bogs, whereas peat bulk densities increase about three times within the uppermost 40 cm, much more than in bogs. Hence, rich fens accumulate peat not because the plant material is especially hard to decompose, is acidic, or has the catotelm especially close to the surface, but because dense, rapidly produced inputs outweigh the relatively rapid decomposition process of the upper peat column. Author Contributions: DHV conceived study; KS, KW, SF, & DHV performed research; DHV, KW analyzed data; DHV, KW contributed new methods; DHV, KW wrote the paper.     

Clearcutting Maine: Implications for the Theory of Common Property Resources

One of the basic tenets of the theory of common property resources is that private property rights work to conserve natural resources. There is growing evidence, however, that some large forest owners in Maine are cutting their forests heavily, using poor-quality silviculture techniques. This overexploitation is being done by paper companies, forest contractors, and some private land owners, who are being motivated by very different sets of factors. This article explores the reasons that private owners of forest resources are overexploiting their own lands and the implications of this for the theory of common property resources. Secure private property rights alone will not be enough to conserve resources and do away with externalities when the owners are operating in a system demanding constant short-term profits, where they are producing undifferentiated commodities in a highly competitive market, where the future value of slow-growing resources is very low, and where harvesting has so many ramifying biological and social effects.     

Conservation management of Pinus palustris ecosystems from a landscape perspective

Question: Do case studies from silvicultural and restoration studies and applied conservation management in second‐growth Pinus palustris stands provide unique insights for conservation models? Methods: A review of management paradigms that conserve the high biological diversity and rare species, drawn from characteristics in both second‐growth and old‐growth stands, is presented for fire‐maintained Pinus palustris (longleaf pine) forests. Results: A common assumption that old‐growth stands provide the primary information for the development of conservation management strategies de‐emphasizes lessons learned from second‐growth and restoration studies. Primary conservation management goals for the Pinus palustris ecosystem include the perpetual regeneration of the fire‐maintained forest and conservation of the characteristically high biological diversity and rare species. Several attributes, such as a sustained population of Picoides borealis (red‐cockaded woodpecker), Aristida stricta (wiregrass)‐dominated ground cover, and undisturbed upland‐wetland ecotones, can predict a diverse and ecologically functional ecosystem. Such indicators are linked to critical structural and functional features of the system and reflect previous land management histories that suggest sustainable approaches. Conclusions: A traditional definition of ‘old‐growth’ relying on overstorey may be limited in describing important features of healthy, diverse Pinus palustris ecosystems. Some characteristics are significantly more important for maintenance of diversity than age of the trees and these features may be present in old‐ or second‐growth forests. We advocate that the management history, structural characteristics and landscape context of stands that harbour desirable conservation attributes (red‐cockaded woodpeckers, wiregrass, gopher tortoises and undisturbed upland‐wetland ecotones) can be used as indicators to identify important conservation and forest management principles.     

The Effect of Felling on the Occurrence of Microfungi Stimulatory to Armillaria Rhizomorph Formation in Thin Roots of Quercus robur

Eight fungal assemblages were isolated from thin branch roots (0.5–1 mm diameter) of living oak trees (Quercus robur) and their stumps 2 years after felling. The roots were serially washed or surface‐sterilized with ethanol and hypochlorite. The thin roots were inhabited by fungi that are stimulants of Armillaria rhizomorphs as found previously in thick roots (0.5–1 cm diameter). However, unlike thick roots, the densities of the fungi in serially washed roots were significantly less in stump roots than in living roots. Among the most common ‘stimulants’, the frequencies of Cylindrocarpon didymum, Mortierella gracilis, Mor. microspora var. macrocystis, Mycelium radicis atrovirens, Nectria grammicospora, Pseudogymnoascus roseus and Sporothrix schenckii were usually significantly greater in stump roots than in living roots, while the frequencies of Chrysosporium merdarium, Cy. destructans, Mor. hygrophila, Penicillium adametzii, Pe. citrinum, Pe. daleae, Pe. janczewskii and Pe. spinulosum were usually significantly less in stump roots. The frequency of Trichoderma viride was less in the stump roots. Serial washing of roots was more effective than chemical surface‐sterilization in the detection of Armillaria rhizomorph ‘stimulants’. The significance of these findings in the ecology and risk assessment of Armillaria in plantations is discussed.     

Polytrichum strictum as a Nurse-Plant in Peatland Restoration

Polytrichum strictum is a pioneer plant frequently found on bare peat substrate after perturbations (fire, peat extraction). Can this moss facilitate the return of Sphagnum species or other boreal plants after disturbances? Field surveys of abandoned peatlands after peat extraction revealed that Sphagnum was always found in association with P. strictum carpets. We conducted field experiments in abandoned peatlands and showed that P. strictum carpets were able to keep Sphagnum fragments more humid than bare peat but only when the P. strictum carpets were not totally bone dry. In general, daytime temperatures beneath P. strictum carpets and fragments were reduced during the day and increased during the night compared to bare peat. Polytrichum strictum carpets acted as a seed trap, retaining more artificial seeds than bare peat. Polytrichum strictum can be a nurse‐plant: after 16 months, vascular plants transplanted in the P. strictum carpet were healthier than the ones planted on bare peat. The use of P. strictum as a nurse‐plant in boreal forest or peatland restoration is recommended for sites prone to frost heaving and with harsh microclimatic conditions.     

城市林业概述与发展趋势

随着社会经济的快速发展和城市化进程的加快,城市环境问题日益成为社会各界关注的焦点,城市林业在城市建设与发展中的地位和作用越来越受到重视。从自然属性与社会属性,地域范围与层次的角度介绍了城市林业的基本概念和内涵,并比较了城市林业与传统林业、现代园林在属性、经营管理和功能方面的差别。借助已有的研究数据和成果,阐述了城市林业在城市发展中的作用,提出了现代城市林业面临的机遇和挑战以及未来发展趋势。