An application of ordination to the identification of forest types

Summary The problems of allocating new vegetation stands to an existing classification are outlined. As one solution, the vegetation samples from an area may be ordinated by reciprocal averaging and classified by dividing the ordination into community-types. The ordination scores for a short list of species present in a new sample may then be averaged to locate that sample on the ordination axes and in one of the community-types. The method is tested by comparing estimates from incomplete species lists with that from a complete list of species in an forest stand in southern Ghana.We gratefully acknowledge the assistance of Mr. M.O. Hill in the correct formulation of the coordinate estimation procedure.     

Faster redox fluctuations can lead to higher iron reduction rates in humid forest soils

Iron (Fe) minerals play an important role in carbon (C) and nutrient dynamics in redox fluctuating soils. We explored how the frequency of redox oscillations influence Fe reduction rates and C content in Puerto Rican soils. We hypothesized that iron reduction rates would be faster during short oscillation periods than in longer oscillation periods. Surface soils from an upland valley in a humid tropical forest were exposed to systematic redox oscillations over 49 days. The oxidation events were triggered by the introduction of air (21% O₂), maintaining the time ratio under oxic or anoxic conditions at 1:6 (τ_ox/τ_anox). After pre-conditioning the soil to fluctuating redox conditions for 1 month, we imposed 280- and 70-h (or 11.67- and 2.5-day) redox oscillations, measuring Fe^II every few days. We found that by the end of the experiment, Fe reduction rates were higher in the short oscillation period (τ_ox = 10 h, τ_anox = 60 h) than in the long oscillation period (τ_ox = 40 h, τ_anox = 240 h). Carbon and nitrogen loss however was similar for both treatments. These results suggest the characteristics of redox fluctuations can alter rates of Fe reduction and potentially influence ecosystem processes that depend on iron behavior.     

Old rural parks support higher biodiversity than forest remnants

One of the main challenges in biodiversity conservation is to curb a further degradation and loss of high-quality habitats. In agricultural matrix landscapes, the detection of alternative habitats for habitat specialists may be a solution. Historic old parks or landscape gardens around manor houses and castles are cultural heritage of nobles, but their value in harbouring biodiversity is poorly acknowledged. Therefore we evaluated the potential of old rural parks to serve as a habitat for nemoral forest species. We recorded stand structure and the presence of forest biodiversity indicators in 74 closed-canopy stands of historic parks and compared them with 93 neighbouring mature forest remnants on ancient forest land. We estimated the importance of stand structure in relation to habitat type on biodiversity indicators. Finally we suggest single-value indicator-complexes for the cost-efficient assessment of the conservation value of forests and forest-like habitats. Park stands outclassed reference forests in several individual structural characteristics, and in combined indicators of habitat quality and biodiversity. Forests had higher estimates for the combined indicator of dead wood, but large-diameter dead wood types were more abundant in parks. Woodpeckers, several old-growth indicator epiphytes and forest herbs had successfully become established in planted forest-like park fragments. Old rural parks resemble high-conservation-value forests more than the best preserved contemporary forest remnants. After the century needed to overcome immigration delay, old parks do provide a refugium for temperate deciduous forest species. Consequently, biodiversity-targeted management should retain and enhance old-growth attributes in forests and on the peripheries of parks: e.g. preserving old trees to provide service for epiphytes, hollow trees and an understorey mosaic for birds and bats; dead wood elements for saproxylic insects and fungi; limited mowing frequency and increased cutting height for forest herbs. Forestry should enhance the recovery of mixed deciduous stands and avoid conifer plantations.     

Forestry's fertile crescent: the application of biotechnology to forest trees

Relative to crop plants, the domestication of forest trees is still in its infancy. For example, the domestication of many crop plants was initiated some 10,000 years ago in the so-called 'Fertile Crescent' of the Middle East. By contrast, the domestication of forest trees for the purposes of producing more fibre began in earnest in the last half century. The application of biotechnology to forest trees offers a great potential to hasten the pace of tree improvement for desirable end uses. This review outlines some of the progress that has been made in the application of biotechnology to forest trees, and considers the prospects for biotechnologically based tree improvement in the future.     

Wintering forest birds roost in areas of higher sun radiation

We analyze environmental determinants of roost site selection by tree gleaning passerines wintering in a Mediterranean montane oakwood at a craggy area of high variation in altitude and hill-shading pattern. We hypothesize that in temperate latitudes of cold winter climate, birds should spend the night in areas of low altitudes, higher temperatures, and higher solar radiation in order to minimize thermoregulation costs during resting time and to improve foraging conditions just before and after roosting. We study night occupation of woodland locations by the presence of feces in 159 wooden nest boxes (i.e., under identical controlled roosting situations). We employ GIS methods to quantify solar radiation at each location surrounding the nest boxes and data loggers to measure air temperature in the field. Birds prefer to roost in forest patches with higher solar radiation, where the period of light available for foraging is extended and thermoregulation costs during daytime are minimized. They also selected woodland patches with taller trees, a pattern consistent with their foraging preferences for trunks and branches. Other environmental variables played a negligible role in determining the selection of roost sites. Here, we show, for the first time, the importance of sun radiation determining where to spend the night in wintering birds and call attention on considering the thermal space in forest management. Forest management should preserve woodland patches with taller trees more exposed to solar radiation to enhance winter habitat suitability for birds in these Mediterranean oakwoods.     

Comparison of Canavanyl-Envelope Proteins to Normal Envelope Proteins

Electrophoretic analysis showed arginine- and canavanine-containing envelope proteins to be qualitatively the same. Quantitative differences may be due to rapid degradation of some canavanine-containing envelope proteins.     

Boreal forest plant species responses to pH: ecological interpretation and application to reclamation

Aims

Reclamation following oil sands mining in northeastern Alberta (Canada) creates adverse reforestation soil conditions, including extreme pH values. We elucidated pH tolerance limits of boreal plant species and how pH affects nutrient uptake in these plants.

Methods

We measured growth, gas exchange, and foliar nutrient concentration of 15 common northern boreal forest plants after eight weeks exposure to root zone pH ranging from 5.0 to 9.0. Cluster analyses were used to group these species based on their pH responses.

Results

Based on their growth and gas exchange responses to pH, the 15 plant species could be divided into five groups, each of which contained species that commonly co-occur in particular boreal forest site types. For the foliar nutrient responses to pH, the 15 species could be grouped into only two categories; both showed decreases in foliar N, P, Fe and Zn concentration with increasing pH, with a more pronounced effect on the group that included trembling aspen, paper birch and chokecherry.

Conclusions

The evidence of differential adaptation to pH by habitat type suggests the importance of soil pH as a factor affecting boreal plant species distribution and could be helpful for selection of species suitable for reclamation of sites with altered soil pH.

     

BP网络模型和LOGIT模型在森林害虫测报上的应用初报——以安徽省潜山县马尾松毛虫为例

以安徽省潜山县马尾松毛虫测报为例,在潜山县全县设置102个诱捕点,诱集越冬代成虫,并同时记录环境因子数据,例如树高、树龄、坡向、植被等。以这些环境因子为测报因子,以性外激素诱集到的雄蛾数代表田间实际发生情况,构建了森林重要害虫-马尾松毛虫的分类测报模型-BP人工神经网络和概率测报模型。BP网络模型的拟合率为100%,预留样检验报准率为100%。LOGIT模型的一致对率为74%。两类模型的拟合结果和预测结果基本吻合。BP网络的测报能力优于LOGIT模型。     

Covariance NMR in higher dimensions: application to 4D NOESY spectroscopy of proteins

Elucidation of high-resolution protein structures by NMR spectroscopy requires a large number of distance constraints that are derived from nuclear Overhauser effects between protons (NOEs). Due to the high level of spectral overlap encountered in 2D NMR spectra of proteins, the measurement of high quality distance constraints requires higher dimensional NMR experiments. Although four-dimensional Fourier transform (FT) NMR experiments can provide the necessary kind of spectral information, the associated measurement times are often prohibitively long. Covariance NMR spectroscopy yields 2D spectra that exhibit along the indirect frequency dimension the same high resolution as along the direct dimension using minimal measurement time. The generalization of covariance NMR to 4D NMR spectroscopy presented here exploits the inherent symmetry of certain 4D NMR experiments and utilizes the trace metric between donor planes for the construction of a high-resolution spectral covariance matrix. The approach is demonstrated for a 4D (13)C-edited NOESY experiment of ubiquitin. The 4D covariance spectrum narrows the line-widths of peaks strongly broadened in the FT spectrum due to the necessarily short number of increments collected, and it resolves otherwise overlapped cross peaks allowing for an increase in the number of NOE assignments to be made from a given dataset. At the same time there is no significant decrease in the positive predictive value of observing a peak as compared to the corresponding 4D Fourier transform spectrum. These properties make the 4D covariance method a potentially valuable tool for the structure determination of larger proteins and for high-throughput applications in structural biology.     

Adherence of Vancomycin to Proteins

Vancomycin possesses the unusual property of promoting the aggregation of proteins. It also binds to itself (dimerization). Both properties may be related to its antimicrobial activity and we report here procedures to measure them. The position of the negative ellipticity band in the near ultraviolet circular dichroism spectrum of the vancomycin monomer shifts as a function of antibiotic concentration and can be used to readily determine the monomer-dimer equilibrium constant. These measurements complement those performed by high-resolution gel filtration to measure the same process. Aggregation of purified proteins was determined by turbidity measurements. Both dimerization and protein aggregation are influenced by anions whose effectiveness is related to their carboxyl pK_a values, thus linking these two properties.     

树木年轮在干扰历史重建中的应用

干扰是影响森林生态系统结构和功能的重要因子,重建森林群落干扰历史可以掌握干扰发生的机制和规律,对森林经营有重要意义。年轮记载了树木逐年的生长历史,利用年轮可以重建不同尺度上干扰的时空格局,具有重建历史长、定年准确和材料容易获得的优点,是森林动态历史研究不可替代的资料。干扰对树木个体的影响可以分为伤害干扰和生长干扰两种类型。不同类型的干扰的特点和对树木的生长影响不同所以重建方法也不同,对树干造成直接伤害的干扰可以利用树干的疤痕重建,如火灾和泥石流等;生长干扰对树木的生长势造成影响,可以通过识别年轮中的生长抑制和释放发生和持续的时间来确定干扰的时间和强度。但是对破坏性的干扰事件要通过群落中个体的建成时间高峰来判断。欧洲和北美地区利用树木年轮重建森林干扰历史的研究已经很广泛,主要包括火灾、虫灾、地质灾害和气象灾害等干扰类型,在中国利用年轮重建群落干扰的研究还处于起步阶段。本文探讨了应用树木年轮重建不同森林干扰事件的方法,总结了不同的重建方法和干扰重建取得的进展,并指出了以后研究的方向,为以后的干扰重建提供了参考。     

森林生态系统中土壤微生物的作用与应用

土壤微生物作为森林生态系统的重要组成部分,在林业可持续发展中扮演重要角色．本文就土壤微生物在森林生态系统中的作用作了综述．内容包括：土壤微生物区系及生物量在林业可持续发展中的作用、菌根在林业可持续发展中的作用、植物病原微生物对林业可持续发展的影响、PGPR在林业可持续发展中的作用．并对其今后的发展趋势及应用前景等问题作了探讨,提出了今后应进一步开展的研究方向．     

2-DE技术中疏水性和碱性蛋白质的研究进展

双向凝胶电泳(2-DE)具有高分辨率、高通量等特点,已被广泛地用于蛋白质组的分离．但是它在分离疏水性蛋白质和碱性蛋白质时却遇到了极大的挑战．然而,疏水性与碱性蛋白质在全蛋白质中占相当大的比例,且具有很重要的生物学意义．因而,近年来,越来越多的研究者将目标瞄准这些蛋白质,并且取得了一些令人鼓舞的进展：用亚细胞预分离技术,顺序提取法等方法来富集疏水性蛋白质,用一些新的有效的增溶剂如硫脲,ASB一14等来改善疏水性蛋白质的溶解,应用这些技术2一DE可分辨出总平均疏水值达O．80的蛋白质;在碱性蛋白质分离方面,通过等电聚焦预处理,使用窄pH梯度胶条等大大地改善了碱性蛋白质在2-DE中的分离,能分辨出等电点达11．7的蛋白质．现对2-DE技术中疏水性和碱性蛋白质分离的研究进展进行综述．     

Graph theoretical analysis of the phytosociological structure of plant communities: An application to mixed forest

Summary A sampling method, compatible with the theory elaborated in the previous paper, was used to investigate the mixed-forest community of a woodlot in Southern Ontario. The results provide an illustration of the graph theoretical methods developed for the elucidation of a community's phytosociological structure. Certain conjectures about the community are tested and it is found that Goodall's hypothesis concerning the nature of a plant community is supported. The tests also show that the vegetation of the study area forms a single natural grouping despite the disparity of the position ofAcer saccharum and the polarity evident among the other tree species.Nomenclature follows Gleason (1952).From a thesis submitted to the University of Toronto in partial fulfilment of the requirements for the degree of Master of Science.I wish to thank Dr. G. A. Yarranton for his ideas and helpful supervision, and my father for his advice and encouragement. Thanks ag also due to Miss J. E. Ellard and Mr. S. Roy who helped prepare the figures. This research has been supported by a National Research Council of Canada and by NRCC grant A-2910.     

Nonspecific Adsorption of Proteins to Microplates

When a solution of purified adenovirus hexon proteins was diluted in polystyrene microplates without carrier proteins in the diluent, a higher rate of hexon adsorption to the microplates at higher dilutions took place. Addition of gelatin (0.01%), bovine serum albumin (0.01%), or calf serum (0.2%, vol/vol) to the diluent effectively prevented this adsorption. The adsorption to the microplates of adenovirions and measles virions was also prevented by the carrier proteins in the diluent. Certain additional features which distinguish the microtechnique of Takatsy from conventional macromethods are also discussed.     

Vertebrate Crystallins--from Proteins to Genes

A review of literature on tissue-specific proteins of the vertebrate eye lens and genes coding for these proteins is presented. Particular attention is paid to the most heterogeneous family of crystallins: - and -crystallins, their nomenclature, and the structure of their genes. It is pointed out that mutations in gene coding for ubiquitous crystallins may be related to some forms of cataracts.     

亚热带毛竹林土壤磷组分和微生物对施氮的响应

磷(P)是植物和微生物生长的重要营养元素,亚热带地区土壤P有效性较低,且长期高氮(N)沉降可能会造成土壤P有效性进一步降低。本试验开展于戴云山毛竹林,分析了施N 3年对土壤的基本理化性质、P组分、微生物生物量和酸性磷酸单酯酶活性的影响。结果表明: 施N显著增加了土壤NO₃^--N含量,提高了土壤N有效性,但显著降低了易分解态有机磷占全磷的比例,且总有机碳与总有机P的比例>200。土壤微生物生物量碳、微生物生物量磷、酸性磷酸单酯酶活性、微生物生物量碳/微生物生物量磷和微生物生物量氮/微生物生物量磷随施N量的增加而增加。此外,易分解态有机磷占总磷比例与微生物生物量磷呈显著负相关关系。因此,施N加剧了土壤P有效性限制,提高了微生物对P的需求。