Forestry and soil erosion in Britain – a review

Abstract. Research on soil erosion under forest in Britain is reviewed. Erosion can increase as a result of afforestation in the uplands, sometimes with undesirable consequences for surface water quality. Published rates of erosion are usually close to 'natural' ones, at around 500 kg ha⁻¹ yr⁻¹. Of the forest operations that can lead to erosion ploughing is the most important. Clearfelling may also increase erosion, but little is known of its long-term effects. New developments in forestry may do much to reduce the risk of soil erosion, particularly the replacement of ploughing by subsoiling and the control of drain gradients.     

Genetics. Transposons help sculpt a dynamic genome

New research is showing that the mobile genetic elements called transposons cause more extensive restructuring of the genome than previously thought. Researchers have known for about 20 years that transposons can expand the genome, resulting in the repetitive DNA sequences sometimes called "junk," but the new work indicates that transposons can also contribute to substantial DNA losses. What's more, these changes can be rapid--at least on an evolutionary scale--and may help organisms adapt to their environments.     

Effect of dietary phosphoric acid supplementation on acid-base balance and mineral and bone metabolism in adult cats.

Experimental evidence indicates that maintenance of urinary pH < or = 6.4 is the single most effective means of preventing feline struvite crystalluria or urolithiasis of noninfectious causes. This may be accomplished by dietary acidification, but must be moderated to avoid potential adverse effects of excessive acidification, including bone demineralization, negative calcium balance, potassium depletion, and renal disease. Effects of chronic dietary phosphoric acid supplementation on acid-base balance and on mineral and bone metabolism were investigated in adult, domestic cats. One group of 6 cats was fed a basal, naturally acidifying diet without added acidifiers, and another group of 6 cats was fed 1.7% dietary phosphoric acid. Changes observed during 12 months of study included development of noncompensated metabolic acidosis, increased urinary calcium excretion, and lower but positive calcium balance in cats of both groups. Urinary pH decreased in cats of both groups, but was significantly (P < 0.05) and consistently maintained < or = 6.4 in cats given dietary phosphoric acid. Urinary phosphorus excretion increased in cats of both groups, but was significantly (P < 0.05) greater in phosphoric acid-supplemented cats, leading to lower overall phosphorus balance as well. Potassium balance decreased in cats of both groups, but was only transiently negative in the phosphoric acid-supplemented cats midway through the study, and normalized at positive values thereafter. Plasma taurine concentration was not affected by dietary acidification, and remained well within the acceptable reference range for taurine metabolism. Double labeling of bone in vivo with fluorescent markers was followed by bone biopsy and histomorphometric measurement of several static and dynamic variables of bone formation. Overall indices of bone formation decreased in cats of both groups with age and confinement, but were not affected by dietary phosphoric acid supplementation. Dietary supplementation with phosphoric acid used as the principal inorganic P source to achieve moderate and stable degree of urinary acidification, did not appear over the course of 1 year, to have induced adverse effects on mineral, bone, or taurine balance in these adult domestic cats.     

Cognitive dysfunction and the neurobiology of ageing in cats

With improvements in nutrition and veterinary medicine the life expectancy of pet cats is increasing. Accompanying this growing geriatric population there are increasing numbers of cats with signs of apparent senility. A recent study suggests that 28 per cent of pet cats aged 11 to 14 years develop at least one geriatric onset behavioural problem, and this increases to over 50 per cent for cats of 15 years of age or older. While behavioural changes may result from systemic illness, organic brain disease or true behavioural problems, the possibility of age-related cognitive dysfunction is often overlooked. Studies have revealed a number of changes in the brains of geriatric cats that showed signs of cognitive dysfunction, and potential causes include vascular insufficiency leading to hypoxia, increased free radical damage and the deposition of beta-amyloid plaques and/or the modification of other proteins. By recognising the importance of behavioural changes in old cats, investigating them fully for potentially treatable medical conditions, and instigating dietary and environmental modifications to meet their changing needs, we can make the lives of our geriatric cats much more comfortable and rewarding.     

Establishment of trees on mixtures of pulverized fuel ASH and Gypsum. I. Tree performance

Experiments that investigated the performance of nine tree species planted in pulverized fuel ash (PFA) and gypsum power stattion wastes are described. Lombardy and white poplars, common alder and false acacia were the most successful in gypsum and PFA-gypsum mixtures, but tree growth in pure PFA was unsatisfactory. Co-disposal of gypsum and PFA is the best means of promoting the growth of tolerant species planted in power station wastes. Tree performance is improved if these materials are covered by a soil layer, which promotes tree rooting into the underlying wastes.