Are beech (Fagus sylvatica) roots territorial?

Root competition between conspecific neighbours has been notoriously difficult to determine in intact ecosystems. Here we applied microsatellite markers to genotype beech trees (Fagus sylvatica, L.) and roots in subplots in an undisturbed, old-growth monospecific forest (Hainich, Germany). Roots were quantified and assigned to individuals. As a measure for territoriality, we determined root segregation. The hypothesis was tested that intraspecific root diversity was higher in the geometric centre of a triangle formed by beech trees than at positions closer to the stem of a tree. Space exploration measured as presence of an individual was correlated with stem diameter but not soil occupation. Fine root biomass, intraspecific Shannon diversity, effective numbers of genotypes and Evenness were stable and unrelated to the distance of the target tree. We conclude that beech shows no indication for territoriality or asymmetric competition in the presence of conspecific neighbours.     

The status of lysosomal beta-glucuronidase in liver tissue of swine of different constitution

This paper deals with cellular-physiological changes in regard to adaptative problems in the pig. As an example for lysosomal catabolism, beta-glucuronidase activity in liver tissue of pigs with different constitution is presented. Male slaughter pigs (n = 120), equally distributed on the breeds Piétrain, German Large White and German Landrace, are used for the investigation. The results show significant variances between, as well as within the breeds. Partly high significant, positive correlations exist between beta-glucuronidase activity and survival rates. The importance of beta-glucuronidase activity and the lysosomes for adaptative constitution and development in the pig is discussed.     

Impacts of fiber orientation and milling on observed crystallinity in jack pine

Influences of fiber orientation and milling on wood cellulose crystallinity were studied using jack pine wood. The fiber orientation effects were measured by sampling rectangular wood blocks in radial, tangential, and cross-sectional orientations. The influence of milling was studied by analyzing the unsieved and sieved milled wood fractions (all <1,000 μm). Fiber orientation effect was manifested in both X-ray and Raman measurements and was dependent upon the orientation of the sampled wood blocks. In Raman, the observed crystallinity was similar between the blocks sampled on the tangential and the radial faces. However, the estimated values were 5.5 % lower compared to that measured in a powdered sample pellet. Moreover, in these sampling modes, the orientation of the block with respect to the direction of the electric vector of the laser made a difference only for the tangential mode of sampling. When a wood block was sampled on the cross-sectional face, the observed Raman crystallinity was 3.9 % higher from that of the pellet. The observed crystallinity did not significantly differ with change in sample orientation with respect to the electric vector direction. In contrast, the Segal-WAXS study of the blocks indicated that compared to the pellet, the estimated crystallinities in the radial, tangential, and cross-sectional sampling modes were 5, 2, and 11 % lower, respectively. This suggested that the radial and the tangential faces of the blocks can be used to estimate the crystallinity of wood. With regard to the effect of milling on Raman and Segal-WAXS estimates, the wood crystallinity did not depend upon the particle sizes of the fractionated samples and was similar to that of the original unfractionated ground wood.     

Mechanisms of acid buffering and formation of secondary minerals in vitric Andosols

Andosols in the vicinity of active volcanoes receive large inputs of SO₂ and HCl. We studied (i) the mechanisms of acid buffering, (ii) the effect of cation removal on the short‐term acid neutralization capacity and (iii) the consequences of acid buffering for secondary mineral formation in vitric Andosols around the Central American volcanoes Poás and Masaya. Two types of short‐term (24 hour) acidification experiments at pH 3 were conducted to simulate an open system in which leaching prevails (extraction with protonated cation exchange resin) and a closed system with no leaching (pH_stat titration with cation accumulation). Long‐term buffering under field conditions (mean soil pH: 4.6) and its effect on secondary mineral formation were studied by analysis of samples from a transect of decreasing acid input by IR spectroscopy, microscopic methods and geochemical equilibrium modelling. In Poás samples the main short‐term buffering mechanisms at pH 3 are plagioclase dissolution and protonation of organic matter. Long‐term acid buffering under field conditions led to weathering of plagioclase crystals but did not result in protonated carboxyl groups. In Masaya samples mineral and/or glass dissolution are the dominant acid buffering mechanisms in laboratory experiments and under field conditions. For both sites, cation accumulation during pH 3 acidification experiments led to a decrease of the effective acid neutralization capacity. Due to different climatic conditions, Al is precipitated as basaluminite at Masaya while it seems to be susceptible to leaching at Poás. Acid buffering resulted in the formation of amorphous silica at both sites.     

"3S"技术在农业环境信息系统中的应用

农业的可持续发展是当前的热门话题,其中农业生产对环境的影响是研究农业可持续发展的一个重要方面,对它的研究涉及农学、土壤、植物营养、蔬菜、环保、农药、生态、农经、畜牧等众多学科,所需处理的数据也是多种多样的.为了准确、及时地处理、分析这些复杂的数据,不仅需要建立综合性的数据库,还要建立分析处理数据的有效的农业环境信息系统(简称为AEIS)平台,处理不同类型的数据.