PEG和钙离子处理对全缘火棘种子萌发的影响

作为用于防治喀斯特地区石漠化的植物物种,在其种子萌发阶段就必须具有较强的适应干旱和富钙土壤的能力。本文研究了喀斯特地区乡土植物全缘火棘种子萌发过程中对干旱和钙离子的耐受能力,用不同水势的PEG6000溶液和不同浓度的CaCl2溶液分别模拟干旱和富钙土壤环境。结果表明,全缘火棘种子萌发对干旱和钙均具有很强的耐受能力,其耐旱能力强于很多其他喀斯特地区乡土植物的种子,甚至强于一些荒漠植物的种子;其对钙离子的耐受能力也明显强于与其在形态和生态特性上非常相似的同属植物火棘的种子。这或许反映了其对喀斯特地区频发干旱并富钙土壤环境的适应,同时也意味着其具有防治喀斯特地区石漠化的巨大潜力。     

竹蓖舟蛾在广东省的风险分析

文章依据FAO(Food and Agriculture Organization)规定的有害生物风险性分析方法,对竹蓖舟蛾(Besaia goddrica)在广东省的分布、潜在危害性、受害寄主的经济重要性、传播扩散的可能性及危险性管理难度5个方面进行了定性、定量分析,并对竹蓖舟蛾在广东省的危险性作出综合评价.结果表明,竹蓖舟蛾在广东省的综合风险值R为1.74,属于中度危险的林业有害生物.     

Coast live oak, Quercus agrifolia, susceptibility and response to goldspotted oak borer, Agrilus auroguttatus, injury in southern California

Oak mortality is often associated with a complex of decline factors. We describe the morphological and physiological responses of coast live oak, Quercus agrifolia Née, in California to an invasive insect, the goldspotted oak borer (GSOB), Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), and evaluate drought as a potential inciting factor. Morphological traits of 356 trees were assessed and physiological traits of 70 of these were monitored intensively over one growing season. Morphological characteristics of tree health included crown thinning and dieback; bole staining resulting from larval feeding; density of GSOB adult exit holes; and holes caused by woodpecker feeding. These characteristics were used to rank GSOB infestation/injury into four classes, and taken together, they explained 87% of the variation in a principal component analysis. Drought stress on various size/age and infestation classes of Q. agrifolia was measured by assessing branchlet pre-dawn and solar noon xylem water potential, leaf cell turgor potential, and water use efficiency over one growing season. Both morphological and physiological traits were highly variable in mature and old growth trees. Early summer plant water status (branchlet xylem water potential and water use efficiency) was similar between uninfested and newly colonized trees, suggesting that GSOB are not pre-selecting drought-stressed Q. agrifolia for oviposition. By late summer, leaf water and cell turgor potentials were lower in infested than in uninfested mature trees, suggesting that GSOB infestation causes drought stress in these trees. Among the tree size/age classes, infested old growth trees exhibited the greatest change in water use efficiency over the growing season, and showed greater morphological injury symptoms of decline than infested mature trees. Morphological attributes of decline in Q. agrifolia associated with GSOB were correlated weakly with increasing physiological drought stress among infestation classes of trees. We propose that the collection of morphological responses of Q. agrifolia to GSOB described here can be used to monitor the future expansion of the GSOB distribution as well as the GSOB-induced decline of Q. agrifolia in California.     

中国营造速生丰产林林地资源评价及发展潜力估算研究

根据中国第7次全国森林资源清查资料,对全国林地面积在各省市、区的分布情况作了概述,并对现有林地及后备林地质量作了评价,现利用查阅文献和统计调查的方法,分析各省市、区可供发展速生丰产林的林地资源,最后估算出中国发展速生丰产林的林地供给面积为3 222.38万hm2.     

Seasonal and interannual ecophysiological responses of beech (Fagus sylvatica) at its south-eastern distribution limit in Europe

Due to its wide European distribution and its drought-susceptibility, beech (Fagus sylvatica L.) received intensive attention recently in the light of global warming. Contrary to central European beech ecosystems, little is known about the ecophysiology of beech at its south-eastern European distribution limit. Here we tested whether climatic fluctuations during a three-year period affected the ecophysiology of a beech site in Greece. Attention was paid at comparing our findings to the intense effects the 2003 extreme drought had on beech forests in central Europe.     

Managing productivity and drought risk in Eucalyptus globulus plantations in south-western Australia

More than 2.5 million ha of Eucalyptus globulus are now planted across the globe including approximately 500 000 ha in southern Australia. In this region average annual rainfall has declined since 1960 and this trend is predicted to continue in the coming decades. E. globulus is a premium species for paper manufacture and grows well under moderate seasonal water stress. The traits that underpin this rapid early growth also make the species vulnerable to prolonged water stress. We established nitrogen rate and nitrogen-by-stocking experiments in five 2-year-old E. globulus plantations along a climatic gradient in south-western Australia. We measured volume growth, predawn leaf water potential and leaf area index over 7 years or until the plantations were 9 years old. These data were used to explore the relationship between growth and water stress, to understand the mechanistic basis for the relationship and to identify best-bet management strategies for E. globulus plantations in southern Australia.     

Recovery of photosynthetic capacity in Scots pine: a model analysis of forest plots with contrasting soil temperature

Both aboveground and belowground climate affects net primary production (NNP) and forest growth. Little is known about how above and belowground factors interact. The BIOMASS-model was tested to simulate photosynthetic recovery over a wide range of soil temperatures created by snow cover manipulations on tree-scale plots in a 20-year-old Scots pine stand in northern Sweden. The differences in timing of soil warming between the plots covered a span of two months. Carbon assimilation in needles, sap flow, needle water potential and climatic parameters were measured in the field. The simulations revealed that an early start of soil warming gave a relatively early photosynthetic recovery and a 7.5% increase of NPP. Late soil warming delayed the photosynthetic recovery and reduced the NPP by 13.7%. This indicated that soil temperature needed to be accounted for, as well as air temperature, when analysing photosynthetic recovery and NPP in boreal environment. The effects of differences in soil temperature were reflected in the simulated photosynthetic recovery. The model did not fully capture the delay of photosynthetic recovery caused by a late soil warming. It was possible to integrate the complexity of the soil climate effects into a threshold date for soil thaw, using sapflow measurements together with information about air temperature and a day degree sum, as long as water availability was not limiting water uptake by roots. Although a more realistic mechanism than that currently in BIOMASS is desirable as climate change shifts the typical patterns of interplay between air and soil temperature dynamics.     

Potential long-term growth gains from early clump thinning of coppice-regenerated oak stands

A study was established in the Missouri Ozarks to evaluate coppice regeneration of oak. Five years after a 32-year-old stand was clearcut and regenerated naturally through stump sprouts, the dominant sprout on each stump was identified based upon height. Treated plots were thinned to the single dominant sprout on each stump whereas control plots were not thinned. Twenty-five years later the largest 247, 371, 494, and 618 stems per ha were examined and height of the dominant sprout at age 5 was found to be strongly related to dbh at age 30 in both thinned and unthinned plots. However, in the thinned plots, the largest 494 stems per ha were on average 11%, 28%, and 58% greater, respectively, in height, dbh, and volume compared to similar dominant sprouts in unthinned plots. Logistic regression analysis was used to develop curves for the evaluation of potential gains from clump thinning. In this analysis, the average height of a stand at age 5 was used to estimate thinning gains at age 30.     

A Discussion on Drought Tolerance Through Hydraulic Architecture of Woody Plants

In this paper, ten woody plants grew on the campus of the Beijing Forestry University were selected for measuring hydraulic architecture parameters and water potential of one-year-old twigs. The results show that day and night change of water potential and hydraulic architecture parameters appear to be obviously convex trend. The relationship models between water potential and hydraulic conductivity, special conductivity and leaf special conductivity were respectively established, which were simulated by equations Y=axb and Y=ax2 bx c, through which the parameters physiological meanings were discussed. The results show also show that embolism vulnerability of ten tree species was Robinia pseudoacacia> Gleditsia sinensis> Acer truncatum> Prunus davidiana> Cornus alba> Platycladus orientalis> Cedrus deodara> Pinus bungeana> Pinus tabulaeformis> Jasminum nudiflorum, and that the water transport efficiency in xylem and embolism vulnerability of the species are ring-porous species> diffuse-porous species>non     

Effect of CCC and daminozide on growth of silver birch container seedlings during three years after spraying

Applications of growth retardants, daminozide and CCC (chlormequatchloride), were studied in order to determine their effects on morphology and post-planting growth of silver birch (Betula pendula Roth) container seedlings. Daminozide was sprayed once (on 28 June at concentrations of 1.0 – 6.0 g l^–1) and CCC was sprayed twice (on 29 June and 27 July at concentrations of 0.5–3.0 gl^–1). Height growth, morphology of seedlings at the end of the growing season, the shoot and root growth potential the following spring and field performance during the following seasons were measured. During the first summer in the nursery, both daminozide and CCC retarded height growth,but daminozide was more effective. The effects of compounds on stem diameter during the summer of application were small. Neither of the compounds affected the field performance of seedlings. The most suitable applications for retardation of height growth, without negative effects on other morphological variables, were 4 g l^–1 (32 mg per seedling) for daminozide and 2 g l^–1 (16 mg per seedling), sprayed in two applications, for CCC.