The potential of high spatial resolution information to define within-vineyard zones related to vine water status

The goal of this study was to test the usefulness of high-spatial resolution information provided by airborne imagery and soil electrical properties to define plant water restriction zones within-vineyards. The main contribution of this is to propose a study on a large area representing the regions’ vineyard diversity (different age, different varieties and different soils) located in southern France (Languedoc-Roussillon region, France). Nine non-irrigated plots were selected for this work in 2006 and 2007. In each plot, different zones were defined using the high-spatial resolution (1 m²) information provided by airborne imagery (Normalised Difference Vegetation Index, NDVI). Within each zone, measurements were conducted to assess: (i) vine water status (Pre-dawn Leaf Water Potential, PLWP), (ii) vine vegetative expression (vine trunk circumference and canopy area), (iii) soil electrical resistivity and, (iv) harvest quantity and quality. Large differences were observed for vegetative expression, yield and plant water status between the individual NDVI-defined zones. Significant differences were also observed for soil resistivity and vine trunk circumference, suggesting the temporal stability of the zoning and its relevance to defining vine water status zones. The NDVI zoning could not be related to the observed differences in quality, thus showing the limitations in using this approach to assess grape quality under non-irrigated conditions. The paper concludes with the approach that is currently being considered: using NDVI zones (corresponding to plant water restriction zones) in association with soil electrical resistivity and plant water status measurements to provide an assessment of the spatial variability of grape production at harvest.     

Climate change impacts on forest landscapes along the Canadian southern boreal forest transition zone

Context

Forest landscapes at the southern boreal forest transition zone are likely to undergo great alterations due to projected changes in regional climate.

Objectives

We projected changes in forest landscapes resulting from four climate scenarios (baseline, RCP 2.6, RCP 4.5 and RCP 8.5), by simulating changes in tree growth and disturbances at the southern edge of Canada’s boreal zone.

Methods

Projections were performed for four regions located on an east–west gradient using a forest landscape model (LANDIS-II) parameterized using a forest patch model (PICUS).

Results

Climate-induced changes in the competitiveness of dominant tree species due to changes in potential growth, and substantial intensification of the fire regime, appear likely to combine in driving major changes in boreal forest landscapes. Resulting cumulative impacts on forest ecosystems would be manifold but key changes would include (i) a strong decrease in the biomass of the dominant boreal species, especially mid- to late-successional conifers; (ii) increases in abundance of some temperate species able to colonize disturbed areas in a warmer climate; (iii) increases in the proportions of pioneer and fire-adapted species in these landscapes and (iv) an overall decrease in productivity and total biomass. The greatest changes would occur under the RCP 8.5 radiative forcing scenario, but some impacts can be expected even with RCP 2.6.

Conclusions

Western boreal forests, i.e., those bordering the prairies, are the most vulnerable because of a lack of species adapted to warmer climates and major increases in areas burned. Conservation and forest management planning within the southern boreal transition zone should consider both disturbance- and climate-induced changes in forest communities.

     

Environmental drivers of <Emphasis Type="Italic">Ixodes ricinus</Emphasis> abundance in forest fragments of rural European landscapes

Background

The castor bean tick (Ixodes ricinus) transmits infectious diseases such as Lyme borreliosis, which constitutes an important ecosystem disservice. Despite many local studies, a comprehensive understanding of the key drivers of tick abundance at the continental scale is still lacking. We analyze a large set of environmental factors as potential drivers of I. ricinus abundance. Our multi-scale study was carried out in deciduous forest fragments dispersed within two contrasting rural landscapes of eight regions, along a macroclimatic gradient stretching from southern France to central Sweden and Estonia. We surveyed the abundance of I. ricinus, plant community composition, forest structure and soil properties and compiled data on landscape structure, macroclimate and habitat properties. We used linear mixed models to analyze patterns and derived the relative importance of the significant drivers.

Results

Many drivers had, on their own, either a moderate or small explanatory value for the abundance of I. ricinus, but combined they explained a substantial part of variation. This emphasizes the complex ecology of I. ricinus and the relevance of environmental factors for tick abundance. Macroclimate only explained a small fraction of variation, while properties of macro- and microhabitat, which buffer macroclimate, had a considerable impact on tick abundance. The amount of forest and the composition of the surrounding rural landscape were additionally important drivers of tick abundance. Functional (dispersules) and structural (density of tree and shrub layers) properties of the habitat patch played an important role. Various diversity metrics had only a small relative importance. Ontogenetic tick stages showed pronounced differences in their response. The abundance of nymphs and adults is explained by the preceding stage with a positive relationship, indicating a cumulative effect of drivers.

Conclusions

Our findings suggest that the ecosystem disservices of tick-borne diseases, via the abundance of ticks, strongly depends on habitat properties and thus on how humans manage ecosystems from the scale of the microhabitat to the landscape. This study stresses the need to further evaluate the interaction between climate change and ecosystem management on I. ricinus abundance.

     

Quantitative and qualitative assessment of milk production after pharmaceutical induction of lactation in the mare

The induction of lactation is performed in ruminants by steroidogenic impregnation, followed by drugs intended to increase prolactin secretion. The aim of this study was to induce lactation in barren mares and to evaluate milk production. Five treated and 5 control mares were used in June and September in year 1, and 12 mares were used in year 2. Mares were administered a vaginal pessary (500 mg altrenogest and 50 mg estradiol benzoate) for 1 week. The 2nd week, another sponge with 100 mg estradiol benzoate was administered, together with 50 mg/100 kg body weight (BW) sulpiride in oil (IM q12h). All mares were milked by hand. Drug treatment was stopped after I L was obtained. Milk production and composition and plasma prolactin concentration were measured. In year 2, the same steroid treatment was applied, but mares received sulpiride (n = 6) or domperidone (1.1 mg/kg PO q12h) (n = 6). A milking machine and oxytocin injections 1 minute before the start of milking were used. In year 1, all treated mares started milking within 1-5 days after sulpiride treatment. Mean daily milk production was 0.88 +/- 0.52 L/500 kg BW. Milk immunoglobulin G (IgG) contents increased in all mares (IgG concentration range, 14-92 g/L). Plasma prolactin increased during sulpiride treatment (range. 27.7 +/- 2.9 to 43.7 +/- 6.7 ng/mL [before] to 289.0 +/- 7.8 ng/mL during treatment, P < .001). In year 2, results were similar to those in year 1, with peak IgG concentrations ranging from 4.2 to 106.7 g/L and a larger daily milk production (3.13 +/- 0.75 with sulpiride and 3.45 +/- 0.51 L/500 kg BW with domperidone). In conclusion, lactation can be induced in mares within 2 weeks, and some mares produce good-quality colostrum.     

Body size evolution and habitat colonization across 100 million years (Late Jurassic–Paleocene) of the actinopterygian evolutionary history

Fishes are characterized by their capacity to occupy all aquatic environments and by their amazing range of size and morphology. While it is known that habitat influenced the diversity dynamics of fish clades, studies on environmental colonization events through the evolutionary history of ray‐finned fishes have yielded conflicting results as to the origin of modern clades and preferential directions of shifts. The effects of habitat over morphological evolution such as body size remain poorly known in vertebrates. However, body size evolution is more frequently addressed in terms of variation through time and numerous studies have demonstrated that successive taxa within a clade tend to increase in size through time (Cope's or Depéret's rule). We use phylogenetic comparative methods on a genus‐level actinopterygian super‐tree based on extant and fossil data covering the Late Jurassic‐Paleogene interval. Results indicate marine ancestry for freshwater lineages and a dominance of colonizations from marine clades towards other habitats. Similar trends in environment occupancy among different ray‐finned clades are explored. Three main trends affecting non‐closely‐related clades are recognized: (i) the freshwater invaders, (ii) the predominantly marine dwellers and (iii) the environmentally labile fishes. Habitat effects on body size evolution are not statistically supported, but most actinopterygian subclades originate from small‐sized ancestors and tend to increase in size in the course of their evolutionary history. This trend is clear for lineages restricted for long periods of time in the same environments, either marine or freshwater, but it is not observed in environmentally labile fish lineages.     

Digestibility of starch in Penaeus vannamei: in vivo and in vitro study on eight samples of various origin

Apparent digestibility coefficients (ADC) of carbohydrate, protein and lipid were investigated in Penaeus vannamei (18–25 g) with diets containing eight starches of various origin. Test ingredients, included at a level of 35% of diet, were native (NC) or gelatinized (GC) corn starch, waxy corn starch, either native (XC) or gelatinized (GX), high amylose corn starch (AC), potato starch, either native (NP) or gelatinized (GP), and native wheat starch (NW). Experimental diets differed only in the type of starch. Chromic oxide was included as a marker. On each starch sample, water solubility index (WSI) was determined and in vitro digestibility assays were carried out with shrimp digestive gland homogenates in order to evaluate correlations between criteria. In vitro digestibility was estimated as the initial rate of hydrolysis (IRH) in micrograms of reducing units per minute per microgram of substrate in glucose equivalents. Starch ADC ranged from 63.1 (AC) to 95.8% (GX), WSI ranged from 0.06 (NP) to 0.69% (XC) for native starch and from 55 (GX) to 85% (GP) for gelatinized starch, while IRH was between 17 (AC) and 89.10⁻⁴ μg min⁻¹ μg⁻¹ (GC). Significant differences (P < 0.05) appeared within each of the parameters depending on the source of dietary starch; in vitro tests were significantly (P < 0.05) correlated with each other as was IRH with starch ADC (y = 8.0 In(10⁴x) + 59.0; R² = 0.81; x representing IRH). IRH appeared to be more suitable than WSI to predict in vivo digestibility for starch. Protein and lipid ADC which ranged from 94.1 to 97.8% and from 76.6 to 84.8%, respectively, were also significantly affected, thus indicating some associative effects.     

Using high protein distiller's dried grain product to replace corn protein concentrate and fishmeal in practical diets for the Pacific white shrimp Litopenaeus vannamei

An 8‐week growth trial was conducted to evaluate the use of a high protein distiller's dried grain (HPDDG, NexPro®, Flint Hills Resources, LP, Wichita, KS) on the growth performance of juvenile Pacific white shrimp Litopenaeus vannamei. In the growth trial, graded levels of HPDDG (0.00, 10.00, 15.00, and 20.00%) were used to replace corn protein concentrate (CPC: 12.60, 6.30, 3.15, and 0.00%) or fishmeal (FM: 17.40, 9.79, 6.00, and 2.21%). A commercially produced open‐feed formulation was also included in the trial as a reference. Each diet was randomly assigned to four replicate groups of 30 shrimp stocked in 0.8 m³ culture tanks. Under green water conditions, in the presence of natural foods, the results indicated that growth performance and feed conversion ratio were not statistically influenced by increasing levels of HPDDG when used to replace CPC. The FM replacement series trial results showed that shrimp fed a diet with 20% HPDDG exhibited significantly decreased trend of biomass. Results of this study demonstrate that HPDDG is a good protein source, and 20% HPDDG can be used to replace CPC in shrimp diets, or up to 15% when replacing FM.