Effects of bamboo Fargesia murielae on plant diversity in fir forest on mountain Shennongjia     

Li Zhaohua  Manfred Denich  Thomas Borsch 《中国林学(英文版)》2004,6(4):17-22

Simultaneous flowering caused a gregarious dieback of umbrella bamboo (Fargesia murielae) all over the world in 1993–2000. Mountain Shennongjia in Central China’s Hubei Province is the only native home of umbrella bamboo, where it dominates the understorey of the farges fir (Abies fargesii) forest between 2 400 and 3 100 m, covering the ground for more than one century before a periodically flowering death. Data from 20 quadrats along a vegetation sequence revealed that the density, coverage, and height of umbrella bamboo negatively affected the species richness, diversity, and evenness of vascular plants in the forest. Local climax community of fir-bamboo was the poorest in species diversity, while the bamboo-free communities (i.e. shrubs and meadows) were bearing a higher species diversity. The simultaneous dieback of umbrella bamboo is an ecological release, which can periodically promote the plant diversity in the fir forest.  相似文献   

Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes     

Motzer T  Munz N  Küppers M  Schmitt D  Anhuf D 《Tree physiology》2005,25(10):1283-1293

We investigated tree water relations in a lower tropical montane rain forest at 1950-1975 m a.s.l. in southern Ecuador. During two field campaigns, sap flow measurements (Granier-type) were carried out on 16 trees (14 species) differing in size and position within the forest stand. Stomatal conductance (g(s)) and leaf transpiration (E(l)) were measured on five canopy trees and 10 understory plants. Atmospheric coupling of stomatal transpiration was good (decoupling coefficient Omega = 0.25-0.43), but the response of g(s) and E(l) to the atmospheric environment appeared to be weak as a result of the offsetting effects of vapor pressure deficit (VPD) and photosynthetic photon flux (PPF) on g(s). In contrast, sap flow (F) followed these atmospheric parameters more precisely. Daily F depended chiefly on PPF sums, whereas on short time scales, VPD impeded transpiration when it exceeded a value of 1-1.2 kPa. This indicates an upper limit to transpiration in the investigated trees, even when soil water supply was not limiting. Mean g(s) was 165 mmol m(-2) s(-1) for the canopy trees and about 90 mmol m(-2) s(-1) for the understory species, but leaf-to-leaf as well as tree-to-tree variation was large. Considering whole-plant water use, variation in the daily course of F was more pronounced among trees differing in size and crown status than among species. Daily F increased sharply with stem diameter and tree height, and ranged between 80 and 120 kg day(-1) for dominant canopy trees, but was typically well below 10 kg day(-1) for intermediate and suppressed trees of the forest interior.  相似文献   

华中神农架箭竹(Fargesia spathacea)群落之海拔多样性(英文)   总被引：5，自引：0，他引：5  

李兆华  曼丹里奇 《林业研究》2002,(3)

通过对华中神农架海拔1500米至2600米之间11个箭竹样方的研究,阐述了箭竹群落物种丰富度,物种多样性,物种均匀性,生活型谱及群落类型的海拔变化。从最低样方(1680米)到最高样地(2570米),微管束植物从30种降为7种,服从线性模型:Y=55.991.83X(R2=0.84,P<0.001);物种多样性从3.18降为1.78,服从线性模型:Y=4.670.10X (R2=0.72,P=0.001;物种均匀度在0.83至0.99之间变化,但与海拔并不相关。在生活型谱中,一年生植物,地下芽植物和大高位芽树木的百分比随海拔升高而升高;灌木和中高位芽树木随海拔升高而降低;多年生草本和半灌木与海拔关系不大。箭竹群落可分为5种类型:常绿阔叶林下,落叶阔叶林下,温性针叶林下,寒温性针叶林与混交林下,纯箭竹林。图4表2参19。  相似文献   

Influence of nutrition on the lipid quality of pond fish: common carp (Cyprinus carpio) and tench (Tinca tinca)     

Werner Steffens  Manfred Wirth 《Aquaculture International》2007,15(3-4):313-319

Like marine fish freshwater fish are an important source of essential fatty acids for human nutrition. However, the fatty acid composition of pond fish can vary considerably and strongly depends on that of the ingested food. Investigations on the fatty acid composition of common carp (Cyprinus carpio) and tench (Tinca tinca) have shown that different methods of rearing and feeding cause substantial variations in the proportions of the n-6 and n-3 polyunsaturated fatty acids of these fish species. Carp reared on the basis of natural food in ponds exhibit high contents of n-6 as well as n-3 fatty acids in their muscle triacylglycerols. On the other hand carp fed supplementary wheat in ponds resulted in somewhat lower levels of these essential fatty acids. High amounts of n-3 fatty acids can be found in carp fed high-energy diets containing high levels of fish oil. Analogous results were obtained in experiments with tench reared under different nutritional conditions. While rearing on the basis of only natural food in ponds as well as feeding supplementary wheat yielded in similar levels of n-3 and n-6 polyunsaturated fatty acids, higher contents of n-3 fatty acids were recorded in tench fed pellets. High levels of n-3 polyunsaturated fatty acids in foodstuffs have positive effects on human health. Experiments with different cultured fish species proved that the fatty acid composition of the edible parts can be influenced by the diet. Therefore, a finishing diet with a suitable fatty acid profile can be used to improve the nutritional quality of fish products of farmed origin.  相似文献   

Allele distributions of two novel SNPs within the sheep Cyp19 gene     

Attila Zsolnai  István Anton  László Fésüs  one Estonba  Manfred Schwerin  Jens Vanselow 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2002,119(6):402-405

Oestrogen is an important regulator of reproduction and growth. The key enzyme of oestrogen biosynthesis, aromatase cytochrome P450, is encoded by the Cyp19 gene. In order to generate genetic markers for the sheep Cyp19 gene, two novel single nucleotide polymorphisms (SNPs), one located in promoter 2 (P2), the other one in intron 9 (I9), were identified by a comparative sequencing approach. The allele distributions of both SNPs were investigated by means of Polymerase chain reaction‐restriction fragment length polymorphism analysis (PCR‐RFLP) in five economically relevant sheep breeds (British Milk Sheep, Carranzana, Latxa Black Face, Latxa White Face, Merino) and three ancient Hungarian breeds kept as gene reserves (Cikta, Racka, Tsigai). In British Milk Sheep, only the intronic SNP was present whereas in Merino, Cikta, Racka, Tsigai, Carranzana, Latxa Black Face and Latxa White Face, both SNPs could be found. This indicates that the newly identified SNPs can be used as markers for the Cyp19 locus in various sheep breeds.  相似文献   

Kohlendioxid-Haushalt in der Gasphase der ungesättigten Bodenzone,dargestellt am Beispiel eines Podsols     

Manfred Albertsen 《植物养料与土壤学杂志》1979,142(1):39-56

Carbon dioxide balance in the gas filled part of the unsaturated zone, demonstrated at a Podzol Carbon dioxide concentration (with a modified Miotke-probe) and moisture distribution (with a neutron-probe) in the unsaturated zone were measured on four test fields (coniferous forest, leafy wood, grass glade, sugar-beet field) in the Segeberger Forst, south of Schleswig-Holstein, Federal Republic of Germany, during September 1976 until August 1977 down to 250 cm depth. An evaluation method to calculate carbon dioxide production rates from any horizontal soil section and carbon dioxide emission rates was established and formulated in FortranIV for computer treatment. The calculation bases on Fick's diffusion laws, which describe the direct proportional relation between diffusive transport and concentration gradient with diffusivity as proportional factor. Special measurements on undisturbed soil samples from the test region showed a relation between diffusivity and the soil parameters water content and porosity, which permits the calculation of diffusivities from moisture data in any soil depth. Seasonal distribution curves of carbon dioxide concentration, production and emission are presented as evaluation result of all data.  相似文献   

Negative charge — pH dependence of organic matter of forest soil under influence of liming as determined from titration curves     

A. Waldemar Wilczynski  Manfred Renger  G. Józefaciuk  M. Hajnos 《植物养料与土壤学杂志》1993,156(3):267-271

The dependences between negative charge and pH for organic matter of limed and unlimed profiles of sandy acidic forest soils were determined on the base of ion exchange and titration curves measurements. Subtracting the titration curves of the supernatant from the titration curves of the respective suspensions the quantities of base consumed by solid phases were determined. They were interpreted in terms of negative charge after corrections with the quantities of initial exchangeable basic cations and exchangeable hydrogen. For investigated organic material the charge increased slowly in acidic pH region and much faster in alkaline pH region. The zones of the fast increase of charge occured at higher pH's for deeper horizons, enriched with fulvic acids. The observed changes of organic matter charge due to liming were related to the increase of fulvic to humic acids ratio. The negative charges of organic matter in limed and unlimed profiles estimated for high pH were better correlated with fulvic to humic acids ratio than when estimated for lower pH levels.  相似文献   

Control of crystal size and lattice formation by starmaker in otolith biomineralization     

Söllner C  Burghammer M  Busch-Nentwich E  Berger J  Schwarz H  Riekel C  Nicolson T 《Science (New York, N.Y.)》2003,302(5643):282-286

The stone-like otoliths from the ears of teleost fishes are involved in balance and hearing and consist of calcium carbonate crystallites embedded in a protein framework. We report that a previously unknown gene, starmaker, is required in zebrafish for otolith morphogenesis. Reduction of starmaker activity by injection of modified antisense oligonucleotides causes a change in the crystal lattice structure and thus a change in otolith morphology. The expression pattern of starmaker, along with the presence of the protein on the growing otolith, suggest that the expression levels of starmaker control the shape of the otoliths.  相似文献   

Differences between tight and loose cultures: a 33-nation study     

Gelfand MJ  Raver JL  Nishii L  Leslie LM  Lun J  Lim BC  Duan L  Almaliach A  Ang S  Arnadottir J  Aycan Z  Boehnke K  Boski P  Cabecinhas R  Chan D  Chhokar J  D'Amato A  Ferrer M  Fischlmayr IC  Fischer R  Fülöp M  Georgas J  Kashima ES  Kashima Y  Kim K  Lempereur A  Marquez P  Othman R  Overlaet B  Panagiotopoulou P  Peltzer K  Perez-Florizno LR  Ponomarenko L  Realo A  Schei V  Schmitt M  Smith PB  Soomro N  Szabo E  Taveesin N  Toyama M  Van de Vliert E  Vohra N  Ward C  Yamaguchi S 《Science (New York, N.Y.)》2011,332(6033):1100-1104

With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change.  相似文献   

High-resolution nuclear magnetic resonance spectroscopy and multivariate analysis for the characterization of beer   总被引：3，自引：0，他引：3  

Duarte I  Barros A  Belton PS  Righelato R  Spraul M  Humpfer E  Gil AM 《Journal of agricultural and food chemistry》2002,50(9):2475-2481

Beer contains a very complex mixture of nutrients, which in this work are identified to some extent by high-field high-resolution nuclear magnetic resonance (NMR) one- and two-dimensional methods. The (1)H NMR spectrum of beer shows a predominance of strongly overlapped peaks arising from several carbohydrates. Minor components are clearly observed both in the aliphatic and in the aromatic regions of the spectrum. With the aid of two-dimensional methods, spectral assignment was carried out, enabling the identification of approximately 30 compounds and identifying about the same number of spin systems for further assignment. The variability of the spectral profile of beers differing in type and label was studied by principal component analysis (PCA), and it was found that, although some distinction is achieved on the basis of the aliphatic and sugar compositions, clearer separation between ales and lagers is obtained by PCA of the aromatic profiles alone. The potential of this technique as a rapid and informative quality control tool is discussed.  相似文献