Better Laws = Better Environment the Role of the Environmental Lawyer in the Reconstruction and Modernisation of the Water Sector in Private Sector Participation

In order to secure a better environment, it is essential to ensure that the right and appropriate laws exist and are enforced. Before any major change is made to the physical environment, careful consideration should be given to the existence of the appropriate legal and organisational structure to ensure that the desired changes and improvements can be satisfactorily accomplished. Private sector participation is often seen as a catalyst for change and improvement in the economic and environmental situation, but, of itself, that will not create the desired cure. As water is a natural monopoly, it is essential to secure and maintain an effective, efficient and independent regulator. Environmental law should be kept under constant review to ensure that it is relevant and that it meets the challenges of the future, as well as securing the victories of the past.     

Daily transpiration rates of woody species on drying soil

Among annual plants, daily transpiration rates, expressed as a fraction of volumetric soil water content available for transpiration, show a common pattern in response to soil drying. Initially, as soil dries, there is little decrease in transpiration rate until water availability has fallen to about one third that at field capacity. With further soil drying, relative transpiration rate decreases in a more-or-less linear fashion until all available water has been used. Data previously obtained for perennial woody species have often been confounded by different methods for determining available soil water. In this study, we investigated the daily transpiration response to soil drying in five woody perennial species: Thuja plicata Donn ex D. Don, Acer rubrum L., Robinia pseudoacacia L., Hibiscus sp. and Ibex aquifolium L. Transpiration was unaffected by soil drying until the initial estimated transpirable soil water fraction had decreased to between 0.23 and 0.32 of that at field capacity. Beyond this point, transpiration rate declined linearly with available soil water fraction until reaching one fifth the rate observed in well-watered plants. With further soil drying, the relative transpiration rates remained between 10 and 20% of that observed in well-watered plants. Maintenance of transpiration at these rates with further soil drying was hypothesized to result from contributions to transpiration of water stored in plant tissues. After taking tissue water storage into account, it was estimated that transpiration was curtailed as the available soil water fraction fell to between 0.26 and 0.37 of that at field capacity, which is comparable to values reported for annual crop plants.     

核18S rRNA 编码基因的多态性表明立枯丝核菌种复合体中菌丝融合群10区别于其他类群的遗传特性

用11个限制性内切酶处理代表11个已报道的立枯丝核菌的菌丝融合群的25个种内类群的161个样品，来研究18S核rRNA的基因区的DNA多态性。该研究采用基于PCR的限制性图谱方法，即对酶催化的DNA扩增片段和亚片段用1个或2个限制性内切酶进行酶切。从这25个种内类群构建了4种类型的DNA限制性图谱，18S rDNA区段的图谱类型Ⅰ代表立枯丝核菌种内类型的大多数分离物，图谱类型Ⅱ和Ⅲ分别代表种内类群2E、9分离物和5C分离物，它们与图谱Ⅰ的区别在于图谱类型Ⅱ少一个限制性位点，图谱类型Ⅲ少2个位点。图谱类型Ⅳ代表种内类群10A和B（或者菌丝融合群10），该图谱表现出重要的限制性位点多样性，即与其余的种内类群或菌丝融合群相比，该具有5种酶切位点，在18rRNA基因的25个限制性位点中有10个具有信息的位点，并被用来进行分析。以前报道的5.8S rRNA基因片段包括转录内间隔区在内的限制性图谱被用来和这些片段农一对准，有12个具有信息的限制性位被鉴定出来，这些数据被单独或混合用于研究类群的相互关系，通过最大相似性和似然法分析表明，菌丝融合群（AG）10明显与这个种复合物中的其他菌丝融合群的大多数分离物不同，且关系较远。     

Photosynthate and nitrogen requirements for seed production by various crops

Seed biochemical composition was the basis for segregating 24 crops into four distinct groups. Nitrogen requirements of pulses and soybeans were so great that sustained seed growth demanded continued nitrogen translocation from vegetative tissues. This translocation must eventually induce senescence in these tissues, restrict the duration of the seed-fill period, and limit seed yield.     

Effects of inclusion of whole-crop pea silages differing in their tannin content on the performance of dairy cows fed high or low protein concentrates

The effect of including high or low tannin forage peas as an alternative to soyabean meal on performance and N efficiency was investigated using 18 dairy cows in two Latin square design studies. Two varieties of forage pea; Racer (coloured flowers; high tannin) and Croma (white flowers; low tannin), were ensiled 12 weeks post sowing. The in situ degradability characteristics of the pea silages were determined using 4 cannulated sheep. The low tannin forage had a higher soluble N (a) fraction and a greater extent of degradation (a + b), resulting in a greater amount of N being predicted to be released in the rumen than the high tannin forage. In experiment 1, cows were fed one of three treatments in each of 3 periods of 28 d duration in a Latin square design; grass silage/whole-crop wheat (0.50:0.50, DM basis) and 8 kg/d of a high protein concentrate (GWH); grass silage/whole-crop wheat/high tannin forage pea silage (0.25:0.25:0.50 respectively, DM basis) and 8 kg/d of a high protein concentrate (HTH) or 8 kg/d of a low protein supplement (HTL). The inclusion of forage peas increased (P < 0.05) DM intake by 1.2 kg DM/d, but there was no effect of dietary treatment on milk yield (average of 23.0 kg/d), composition or live weight change. The efficiency of use of dietary N (N output in milk/N intake) was highest (P < 0.001) in cows when fed GWH (0.289) and lowest in HTH (0.234). In experiment 2, cows were fed one of three treatments in each of 3 periods of 28 d duration in a Latin square design; grass silage/whole-crop wheat (0.50:0.50, DM basis) and 8 kg/d of a high protein concentrate (GWH); grass silage/whole-crop wheat/low tannin forage pea silage (0.25:0.25:0.5 respectively, DM basis) and 8 kg/d of a high protein concentrate (LTH) or 8 kg/d of a low protein concentrate (LTL). Compared with GWH, the inclusion of forage peas increased (P < 0.05) DM intake by 2.0 kg/d, but there was no effect of dietary treatment on milk yield (average of 24.5 kg/d). Milk fat content was highest (P < 0.05) in cows when fed LTL (45.7 g/kg) and lowest in LTH (41.9 g/kg), but there was no effect (P > 0.05) of treatment on daily fat yield or any other milk component. The efficiency of dietary N use was highest (P < 0.001) in cows when fed GWH (0.300) and lowest in LTH (0.234). It is concluded that either high or low tannin forage pea silages can replace approximately 1.1 kg/d of soyabean meal in the diet of mid-late lactation dairy cows without affecting animal performance, but N efficiency for milk production is decreased.     

A review of the physiological effects of alpha2-agonists related to the clinical use of medetomidine in small animal practice

Medetomidine is a relatively new sedative analgesic drug that is approved for use in dogs in Canada. It is the most potent alpha2-adrenoreceptor available for clinical use in veterinary medicine and stimulates receptors centrally to produce dose-dependent sedation and analgesia. Significant dose sparing properties occur when medetomidine is combined with other anesthetic agents correlating with the high affinity of this drug to the alpha2-adrenoreceptor. Hypoventilation occurs with medetomidine sedation in dogs; however, respiratory depression becomes most significant when given in combination with other sedative or injectable agents. The typical negative cardiovascular effects produced with other alpha2-agonists (bradycardia, bradyarrhythmias, a reduction in cardiac output, hypertension +/- hypotension) are also produced with medetomidine, warranting precautions when it is used and necessitating appropriate patient selection (young, middle-aged healthy animals). While hypotension may occur, sedative doses of medetomidine typically raise the blood pressure, due to the effect on peripheral alpha2-adrenoreceptors. Anticholinergic premedication has been recommended with alpha2-agonists to prevent bradyarrhythmias and, potentially, the reduction in cardiac output produced by these agents; however, current research does not demonstrate a clear improvement in cardiovascular function. Negatively, the anticholinergic induced increase in heart rate potentiates the alpha2-agonist mediated hypertension and may increase myocardial oxygen tension, demand, and workload. Overall, reversal with the specific antagonist atipamezole is recommended when significant cardiorespiratory complications occur. Other physiological effects of medetomidine sedation include; vomiting, increased urine volumes, changes to endocrine function and uterine activity, decreased intestinal motility, decreased intraocular pressure and potentially hypothermia, muscle twitching, and cyanosis. Decreased doses of medetomidine, compared with the recommended label dose, should be considered in combination with other sedatives to enhance sedation and analgesia and lower the duration and potential severity of the negative cardiovascular side effects. The literature was searched in Pubmed, Medline, Agricola, CAB direct, and Biological Sciences.     

Tree and livestock productivity in relation to tree planting configuration in a silvopastoral system in North Wales, UK

Silvopastoral systems in Europe offer the potential of introducing environmental benefits while at the same time increasing the diversity of farm outputs. The establishment of new silvopastoral systems by planting young trees into existing pasture was investigated at a site in North Wales, UK. Two tree species, sycamore (Acer pseudo-platanus L.) and red alder(Alnus rubra Bong.), were planted into pasture at a range of densities and planting arrangements. Growth of trees planted in farm woodland blocks (2500 stems ha^–1) was compared with the growth of trees planted at 400 stems ha^–1 in clumps and dispersed throughout the plot and at 100 stems ha^–1 (dispersed). Over the first six years after planting, alder trees were significantly taller and larger in diameter than sycamore. Sycamore trees planted at close spacing in farm woodland or clumped arrangements were significantly larger in diameter than widely spaced sycamore at 100 and 400 stems ha^–1. Livestock productivity was unaffected by the presence of trees during the six-year establishment phase of the system. The planting of trees in a clumped pattern appears to combine silvicultural benefits to tree growth with agricultural benefits of maintaining livestock production while trees are established.This revised version was published online in November 2005 with corrections to the Cover Date.     

Variations in shoot and root growth of three provenances of Faidherbia albida in clay and sand soil

The variation in shoot and root seedling growth traits was compared among three Faidherbia albida(Del).A. Chev. provenances originating from Kenya(Taveta),Malawi(Bolero) and Ghana(Bolgatanga); representing east, south and west Africa, respectively. Bulked seeds from three provenances were grown in two soil types(clay and sand) at the World Agroforestry Centre nursery,Nairobi. Seedlings grown in clay soil had high shoot growth and shoot to root ratios but shorter root length,lower number of nodules and specific root length compared to seedlings in sand soil. Shoot to root ratios reduced with time and this was more pronounced in sand soil. Overall,the Bolero and Taveta provenances had higher growth than the Bolgatanga provenance. This was probably because plants grown in nutrient-rich clay soil invest more in shoot growth as compared to root growth. Longer root growth in sand soil shows a better adaptive mechanism that increases competitive ability and survival in nutrient-poor systems.Variations observed among the seedling variables such us shoot and root growth could be used for early selection for reforestation and agroforestry in predominantly clay and sand soil areas.