Influence of drought on tree rings and tracheid features of Pinus nigra and Pinus sylvestris in a mesic Mediterranean forest

We investigated the influence of climate on the ring width and xylem anatomy of two co-occurring pines (Pinus nigra Arn. and P. sylvestris L.) in the mountains of east-central Spain in order to test their utility for dendroclimatic reconstructions. We developed chronologies of ring width, mean lumen diameter and mean cell-wall thickness (in the earlywood, latewood, and the total annual ring) and the number of cells between 1960 and 2006. Drought, expressed as the standardized precipitation-evapotranspiration index (SPEI), was the main climatic driver of tree radial growth, although trees were also sensitive to temperature (negative effect in previous autumn and current summer) and precipitation (with a general positive effect). P. sylvestris response was stronger to climate of the current year, whereas the effect of previous-year climate was more important for P. nigra. Warm and dry summers reduced ring width, tracheid lumen, and wall thickness in both species, whereas warm winter-spring temperatures had the opposite effect, primarily for P. sylvestris. Previous-year or early-season conditions mainly affected earlywood features, whereas latewood was more responsive to summer climate. Overall, climate appeared to be a stronger limiting factor for P. sylvestris. During periods of drought, cell-wall thickness was reduced while lumen width increased in the latewood of P. sylvestris. This could compromise its hydraulic safety against drought-induced cavitation as our site was close to the southern and dry edge of the species distribution area. Our results suggest that anatomical variables record different and stronger climate information than ring width variables, especially in P. sylvestris. Reconstruction models for SPEI at the 3-month scale were developed for July–August and September–October using principal components regression. The best models included anatomical and width variables of both pine species suggesting that tracheid chronologies can be useful for drought reconstructions especially at mesic sites or with species that encode a mixed drought and temperature-precipitation signal.     

The effect of temperature on sensory quality,chemical composition and growth of carrots (Daucus carota L.). IL Constant diurnal temperatures under different seasonal light regimes

Summary

Carrots of cv. Panther F1 were grown in climate chambers at 9, 12, 15, 18 and 21°C, constant diurnal temperatures at three different periods of the year. The effect of varying solar radiation and temperatures were evaluated on growth, sensory attributes and chemical composition. Higher levels of light significantly increased most chemical and physical variables of the carrot roots. Temperature was the most important factor determining the variation in sensory and chemical variables, whereas for morphological features like root weight, root length and diameter measurements, light was more important than temperature. Principal component analysis (PCA) of chemical and physical variables explained 85% of the total variation by the first three principal components, the first component (PCI) being defined by physical variables, explained 46% of the variation, while the temperature related PC2 explained 32% of the variation. Prediction of sensory variables by chemical or physical variables by means of partial least square (PLS) was higher at low light intensity than at high light intensity.     

Dairy cow mortality. A review

Summary

We reviewed the literature to give an overview over the mortality among dairy cows in countries with a relatively intensive dairy production. A total of 19 studies focussing on dairy cow mortality were identified. Information about objectives, measures of mortality, sample sizes, study designs, causes of death and risk factors from these studies is presented and discussed. Additionally, recommendations for future recordings of mortality that will enable better possibilities for comparison of study results, generalization of results from a study population to a larger population and meta‐analysis are given.     

Characteristics in the epidemiology of bovine viral diarrhea virus (BVDV) of relevance to control

An understanding of the driving forces of BVDV transmission can be gained by considering the reproductive rate, between individuals and between herds. The former determines the prospects for eliminating the infection from herds, and the latter is the key to persistence at the population level. In this paper, the relation between these two characteristics, their underlying parameters and measures and priorities for BVDV control are discussed. A general model for BVDV control is outlined, with bio-security, virus elimination and monitoring as three necessary consecutive elements, and with immunization as an optional step. A distinction is made between systematic and non-systematic approaches to BVDV control (where the former refers to a monitored and goal-oriented reduction in the incidence and prevalence of BVDV infection and the latter to where measures are implemented on a herd-to-herd decision basis and without systematic monitoring in place). Predictors of progress for systematic control approaches in general are discussed in terms of the abilities: to prevent new infections, to rapidly detect new cases of infection, to take action in infected herds and to gain acceptance by stakeholders. We conclude that an understanding not only of the biology, but also of the social factors - human behavior, the motives that makes stakeholders follow advice and the cultural differences in this respect - are important factors in forming recommendations on alternative strategies for BVDV control.     

Effects of clearcutting and site preparation on stormflow volumes of streams in Pinus elliottii flatwoods forests

Three operational-sized watersheds in pine flatwoods of the Lower Coastal Plain in north Florida were isolated and continuously monitored for $\text{3}\text{1}\text{2}$ years. Recording flumes assessed quantity of runoff water. After 1 year of calibration monitoring, two of the watersheds were, harvested, site-prepared, and planted under distinct harvest and regeneration practices.Minimum practices, imposed on one watershed, consisted of manual shortwood harvest of pinelands, roller drum chopping of harvest residues and residual understory, bedding, and planting. Maximum practices, imposed on another, consisted of tree-length logging of pinelands with heavy equipment, extraction of lightwood stumps, burning and windrowing of logging residue and residual understory, harrowing, bedding, and planting.Both silvicultural systems increased stormflow volumes; maximum practices moreso. Under both systems stormflow volumes apparently increased immediately following tree harvests. The increase persisted through site preparation, planting, and subsequently for $\text{1}\text{1}\text{2}$ years without further detectable change.Results of this and two earlier reports on the effects of silviculture on hydrologic regimes of flatwoods forests are reviewed and summary conclusions drawn.