Opening address

Abstract

The 291 preliminary land types in the Karoo Region formed the basis for the demarcation of the 144 Reasonably Homogeneous Farming Areas (RHFAs). The land types were firstly reduced to 23 Floristic Climatic Regions (FCRs) according to character species for certain macroclimatic conditions. The character species were identified by means of computer classification and ordination techniques (PHYTOTAB, TWINSPAN and DECORANA). About 22 soil forms and numerous soil series were found in the Karoo Region. Based on differences in the inherent veld production potential and erodibility of the different soils, as well as differences in slope, nine Veld Soil Potential Classes (VSPCs) were synthesised. The land types in each of the FCRs were, lastly, consolidated according to their similarity in terms of macrocli mate and dominant topographical units and VSPCs, into RHFAs.     

On biological species, species concepts and individuation in the natural world

I am a realist and argue that biological species exist in nature. I also argue that the validity of findings of the many disciplines within the natural sciences employing biological species in their endeavours of inquiry are unequivocally linked to the accuracy of the species used in experiments. Few scientists today see the fundamental importance of taxonomic and systematic studies in both addressing accuracy of diversity and the delineation of species diversity for other areas of science. The basic controversial issues in the debate revolve around opinions regarding the nature of species as either Individuals or Classes, confusion of Species as a taxonomic category and as entities in nature, the varied practitioners studying diversity, a general lack of a Lineage perspective and a gross chauvinistic perspective on the types of data worthy of exposing and delineating diversity. I argue that species in nature are Individuals and form Lineages. As Individuals, they cannot be defined but can only be diagnosed in time. The category Species is a Class with a definition. The difficulties realised by scientists studying biodiversity in ‘defining’ a species hinges upon the fact that as natural entities they cannot be defined. Recognizing and understanding the origins of characters in species is further complicated if one views species in nature as Classes and lacks an appreciation for the Lineage and the origin and retention of traits through time. This forms an interesting paradox that many scientists have fallen victim to wherein species are viewed as Classes (hence definable, but immutable) yet are used to understand the process of descent that involves lineages and Individuals! The pre‐Darwinian Class perspective of species, combined with a common chauvinistic perspective on characters ultimately delays progress and places a ‘glass ceiling’ on species diversity for planet Earth. One resolution to the species and species concept issue is to view the concepts in a hierarchical manner of primary (theoretical) and secondary (operational) concepts. Interestingly, the issue of Individuals versus Classes for naturally occurring entities is much more widespread and exists in many other scientific fields. Thus, a hierarchical perspective of having a primary, nonoperational concept for natural entities and multiple operational concepts serving as ‘tools’ for discovering natural things consistent with the primary concept is a heuristic methodology that is applicable to the advancement of many areas of science.     

Driving factors of synchronous dynamics in brown trout populations at the rear edge of their native distribution

The classical debate about the roles of endogenous factors and external drivers in regulating populations continues to be a very active area of scientific research, and these roles are even more complex in populations located in geographically marginal areas. We tested three hypotheses on two separate brown trout populations inhabiting the southernmost basins of the Iberian Peninsula, with the aims of determining the relationships among (a) rainfall and air temperature for each season preceding fish sampling and the observed age group densities; (b) environmental synchrony and density synchrony for all possible pairs of sites; and (c) physical habitat similarity and the similarity of the density response to climatic drivers among pairs of sites. For this purpose, demographic series (98 surveys at 14 sampling sites), climatic conditions (rainfall and air temperature) and site habitat characteristics (physiogeographic and quality index values) were analysed between 2006 and 2014. The results show how the synchrony in the study populations is the result of a Moran effect directed mainly by winter precipitation and conditioned by the habitat similarity (highlighting the altitude, the distance to the upper limit and IHF index, along with the Euclidian distance among pairs of sites of the whole set of habitat variables). Preserving the heterogeneity of these habitat characteristics will increase the resilience of trout populations that inhabit this rear edge of distribution. The current context of global climate warming predicts extremely drastic changes in the dynamics of external drivers that regulate the trout populations in the study region.     

Partial replacement of fish oil by soybean oil on lipid distribution and liver histology in European sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) juveniles

A 12‐week feeding trial was conducted to evaluate the effects of fish oil replacement by soybean oil, on lipid distribution and liver histology of two commercially important finfish species: rainbow trout (Oncorhynchus mykiss) and European sea bass (Dicentrarchus labrax). Sea bass (16.2 ± 0.5 g; mean ± SD) and rainbow trout (52.1 ± 0.5 g) juveniles were fed one of three isonitrogenous (500 g kg^?1 CP) and isoenergetic (19 kJ g^?1) diets, containing 0% (control, diet A), 25% (diet B) and 50% (diet C) soybean oil. At the end of the experiment, lipid deposition was evaluated in muscle, liver and viscera. Cholesterol and triglycerides levels were also determined in plasma. Tissue total, neutral and polar lipid composition (g kg^?1 total lipids) showed no significant differences within species, regardless the dietary treatment. The same trend was observed for plasma parameters (P > 0.05). Viscera were the preferential tissue of lipid deposition, with 252–276 and 469–513 g kg^?1 total lipid content in trout and sea bass, respectively. Dietary fish oil replacement had no effect on either hepatic lipid droplets accumulation or degree and pattern of vacuolization in the observed liver sections. These data suggest that both sea bass and trout can be fed diets containing up to 50% soybean oil without adverse effects on tissue lipid composition or liver histology.     

三明市杉木,马尾松人工林材种出材率表编制的研究

三明市材种出材率表编制是根据部，省有关材种规格标准，进行现场造材，共收集１１６４株样木，其中杉木５５６株，马尾松６０８株。采用电子计算机对样木进行计算和分析，以确定各树种树高级，径阶、材积、树皮率、出材量和出材率。     

Durability of thermally modified timber from industrial-scale processes in different use classes: Results from laboratory and field tests

Material from four common European processes of industrial heat treatment of timber was examined comparatively with reference to biological laboratory standard tests and field tests in soil contact and above ground. The thermally modified timber (TMT) used in the study was: Plato wood from the Netherlands, ThermoWood from Finland, New Option Wood (NOW) from France, and oil-heat-treated wood (OHT) produced in Germany. Tests of resistance to basidiomycetes (EN 113, 1996) and tests of resistance to soft rotting microfungi and other soil-inhabiting microorganisms (EN 807, 1997) showed substantially lower mass losses of TMT compared with controls. Only slight differences in mass loss were found between the four thermally modified materials. Based on results from laboratory standard tests all tested heat-treated materials were classified as durable to moderately durable [durability class (DC) 2-4], analogous to the classification of natural durability (EN 350-1, 1994). In contrast, the classification of TMT samples after 5.5 years' exposure in soil contact, in accordance with EN 252 (1990), was slightly durable to not durable (DC 4-5), whereas the classification obtained after 5.5 years' exposure in double layers in European hazard class (EHC) 3 (EN 335-1, 1992) was very durable to moderately durable (DC 1-3). On the basis of 5.5 years' field testing, thermally modified material (independent of the treatment process and supplier) appears not to be suitable for in-ground contact application. However, the suitability of TMT for use out of ground in EHC 3 was ascertained and is recommended.     

塔里木河中游胡杨群落结构特征分析

为了了解生长状况良好的胡杨群落,在塔里木河中游沿岸选择具有代表性胡杨群落,设立1 hm2固定样地,调查分析胡杨林群落结构特征。结果表明：胡杨群落垂直层次优势种较为明显,形成以胡杨+柽柳+芦苇、假苇拂子茅为优势种的荒漠河岸林群落类型;胡杨种群属于稳定型种群,个体数量在不同径级之间分布合理;在不同尺度下,胡杨种群均处于集群分布;胡杨种群在不同发育阶段分布格局由聚集分布向随机分布转变。     

Field Photosynthesis Measurements on Black Spruce (Picea mariana): Does Needle Age Matter?

Black spruce (Picea mariana) trees have needles that persist for a number of years, and it is not clear which age class should be evaluated for photosynthesis to best understand physiological responses. Moreover, the impact of sampling current versus older foliage is rarely acknowledged in published literature, even though it may influence the interpretation of results. We compared the photosynthesis rate of current and 1-year-old foliage of black spruce natural regeneration during three growing seasons. The photosynthesis rate was consistently greater for 1-year-old needles compared to current-year needles at the beginning of each growing season; however, after about 1 month, rates were similar between the two age classes. This same pattern was repeated every season and was independent of light availability induced by different harvesting treatments. We suggest that photosynthesis measurements of black spruce should be performed on 1-year-old needles instead of current-year foliage to ensure more uniform photosynthesis values throughout the season.     

Lipids in female northern bluefin tuna (Thunnus thynnus thynnus L.) during sexual maturation

Total lipids, lipid classes, fatty acids and vitamin E contents were measured in ovary, liver, dark muscle, white muscle and mesenteric perigonadal fat in four maturational stages of Atlantic female northern buefin tuna (Thunnus thynnus thynnus L.) during migration to Mediterranean spawning grounds through the Strait of Gibraltar. Ovary lipid content increased significantly by 37.6-fold from inmature to spawning stage, accumulating large quantities of steryl/wax esters, whereas the ratio of mesenteric perigonadal fat (primarily triacylglycerols) weight to ovary weight decreased linearly throughout maturation. In contrast, liver, dark red and white muscles lipid content did not show a major depletion during maturation compared to that of perigonadal fat. The fatty acid composition of ovary from bluefin tuna showed that docosahexaenoic acid (DHA; 22:6n-3) was the most abundant fatty acid and DHA: EPA: AA and DHA: EPA ratios were 19.3/4.3/1 and 4.5/1, respectively. Neutral lipids predominated over polar lipids (2-3:1) in ovary and triacylglycerol and steryl/wax ester were major lipid classes. In general, fatty acid composition of most tissues examined were similar to each other but, in contrast, the fatty acid profile of perigonadal fat was rich in monoenes such as 18:1n-9, 20:1n-9 and 22:1n-11, and DHA decreased significantly at spawning stage. The total lipid balance suggested for the disappearance of lipid from perigonadal fat depots and, to a lesser degree, from muscle and liver depots, reflected lipid utilization for gonadal development on the one hand and non-gonadal metabolism in the other. The former included lipid transferred to the gonad and lipid catabolized to provide metabolic energy for the biosynthesis of gonadal constituents and the later was likely to be lipid catabolism to provide energy for swimming during spawning migration. This revised version was published online in August 2006 with corrections to the Cover Date.     

松嫩平原光稃茅香种群生殖分蘖株数量特征分析

在松嫩平原天然割草场光稃茅香种群的籽实成熟期，将广泛取样的588个生殖分蘖株样本分为10个高度级进行测定，分析的结果表明，株高与花序长度，营养生物量，生殖生物量，总生物量，籽粒千粒重均呈显著的正相关，与生殖生长比率，生殖分配I，生殖分配Ⅱ，每个花序种子生产的数量，结实率均呈显著的负相关，生殖分蘖株数量特征的生态可塑性及其规律性变化，蕴涵着个体生长与生殖策略。