Mechanical control of morphogenesis by Fat/Dachsous/Four-jointed planar cell polarity pathway

During animal development, several planar cell polarity (PCP) pathways control tissue shape by coordinating collective cell behavior. Here, we characterize by means of multiscale imaging epithelium morphogenesis in the Drosophila dorsal thorax and show how the Fat/Dachsous/Four-jointed PCP pathway controls morphogenesis. We found that the proto-cadherin Dachsous is polarized within a domain of its tissue-wide expression gradient. Furthermore, Dachsous polarizes the myosin Dachs, which in turn promotes anisotropy of junction tension. By combining physical modeling with quantitative image analyses, we determined that this tension anisotropy defines the pattern of local tissue contraction that contributes to shaping the epithelium mainly via oriented cell rearrangements. Our results establish how tissue planar polarization coordinates the local changes of cell mechanical properties to control tissue morphogenesis.     

Promoting native trees in shade coffee plantations of southern India: comparison of growth rates with the exotic <Emphasis Type="Italic">Grevillea robusta</Emphasis>

Traditional shade coffee plantations of Kodagu district, in the Western Ghats of southern India, harbor a high density and diversity of trees. Local farmers appreciate native biodiversity, but plantation economics and public policies drive them to gradually replace the original diversified cover with exotic shade trees such as Grevillea robusta, which grows fast and can be easily traded as timber. In order to identify and recommend native timber trees with fast growth rates, we compared the growth performance of four common native species against that of G. robusta, by fitting steel dendrometer bands on 332 shade trees. Results showed that in general G. robusta had the fastest growth rates, but large trees of the native Acrocarpus fraxinifolius had faster growth in the wet western side of the district. Computer projections of long term performance showed that most species were influenced by bioclimatic zone. Species-specific local environmental effects also occurred, including competition from coffee bushes for A. fraxinifolius, influence of aspect for G. robusta, and management block effects for Lagerstroemia microcarpa. Our results show that native species potentially could produce timber at rates equivalent to those of exotic species. However, as in many tropical countries, data on growth rates of native trees within mixed-cover plantations are scarce and this study underlines the urgent need to screen for fast-growing species. Such information provides a strong basis for recommending appropriate changes in public policies that would improve tree tenure security and encourage farmers to grow more native species.     

Soil physico-chemical changes following application of municipal solid waste leachates to grasslands

Concerns about the use of residues from municipal solid waste incinerators (MSWI) in construction materials usually focus on the potential for heavy metals and organic chemicals to leach into drainage waters under the influence of rain. We hypothesised that high level of salts in the MSWI leachates may cause more of a problem, particularly on soil physico-chemical properties. Both bottom ash (BA) and Solidified Air Pollution Control residue (SAPCr) leachates were added to experimental grassland plots. The amounts of Na⁺ increased by up to 13% in soils supplemented with each leachate. A decrease of the soil total porosity (?14%) was evidence of a subsequent adverse physical effect of this strong salinity. The potential for the grass cover type (species composition or density) to limit this adverse effect was discussed. Laboratory tests allowed us to determine that undiluted SAPCr induced slaking of aggregates accompanied by a strong decrease of aggregate stability, to 49% of control values. Undiluted BA induced dispersion of clays and others fine particles, which are then dislodged and transported into pores, causing blockage and decreasing total porosity. Clay dispersion followed by aggregate collapse occurred when soil solution contaminated by SAPCr was diluted by rainwater. This work stressed the importance of accounting for mineral contaminants, such as salts, when conducting an assessment of waste reuse scenarios.     

Thirteen-year monitoring of liming and PK fertilization effects on tree vitality in Norway spruce and European beech stands

The chemical fertility of the forest soils in the Belgian Ardenne is threatened by acidifying and eutrophying deposition and by the nutrient removal due to timber harvesting. Experiments were launched to evaluate the ability of liming and fertilization to improve foliar nutrition, maintain or restore crown condition and promote tree growth. In 1995, 10 liming and fertilization trials were installed in even-aged stands of European beech (5) and Norway spruce (5) distributed throughout the Ardenne. In each stand, two treatments were tested: liming with 3,000 kg ha⁻¹ of dolomitic limestone and liming plus fertilization with 0 to 800 kg ha⁻¹ of rock phosphate and 0 to 350 kg ha⁻¹ of K₂SO₄. Between 1995 and 2006, the foliar Ca and Mg status of spruce and beech trees improved in the limed stands, which limited significantly but did not prevent the decline in crown condition triggered by the summer drought in 2003. For spruce, liming also increased the increment in basal area. The additional fertilization increased the foliar nutrition in P but had no significant effects on soil chemistry and tree vitality.     

Using cover measurements to estimate aboveground understorey biomass in Maritime pine stands

? Understorey plays a major role in forest fluxes and stocks balances, however this compartment is generally poorly quantified. Our objectives were to establish models to estimate understorey biomass using vegetation cover measurements and to investigate upscaling methodologies from stand to regional level.

? Understorey aboveground biomass measurements were undertaken in Maritime pine stands of mesohygric, mesic and dry moorlands in South West France.

? Average biomass stock in this compartment was estimated to 3.50 t DM ha^?1. The more abundant species groups varied with moorland types, with a higher relative contribution of herbaceous species (23.3%), bracken (59.2%) and mosses (31.6%) for mesohygric, mesic and dry moorlands, respectively. For each species group, we established significant relationships to estimate biomass using a volumetric index, based on cover and height measurements. No relationship between stand characteristics and understorey biomass was founded. We investigated the upscaling of these estimations to a several thousands hectare area using understorey cover measurements done along a regular spatial grid. The only significant correlation linked one satellite vegetation index to understorey biomass.

? We successfully developed empirical relationships to estimate the understorey biomass at the stand level. Further investigations could focus on the analysis of understorey variability over a finer space grid and the potential use of satellite vegetation indexes.

     

A Socio-Economic Analysis of French Public Timber Sales

This socio-economic study aims to better understand the functioning and the evolution of timber sales held by the French public forest service. The auction system is the historical institution which has been used for timber sales in France for centuries. The recent trend to develop supply contracts through private agreements has a major impact on the French timber industry, which is criticized for its lack of competitiveness. It accurately raises questions about the timber price issue. Indeed, the auction system plays an important role in price setting. We refer to the auction theory literature to examine the features of French timber auctions: first-price sealed-bid sequential auctions of heterogeneous standing timber lots. In particular, we note that seller's reserve price is kept secret and that, contrary to the general assumption in auction theory, the seller indubitably lacks information about his own reservation value. Finally, the difficulty of defining a “fair market price” remains a central issue in public timber sales.     

Does milk yield reflect the level of welfare in dairy herds?

Under the assumption that milk yield may be reduced in herds with impaired welfare, the present study aimed at investigating whether milk yield could be used as a reliable indicator of welfare. In 125 commercial French dairy herds, the association between the welfare of the herd (evaluated using the Welfare Quality assessment protocol) and cow milk yield was investigated using linear mixed models. Positive associations were identified between milk yield and low aggressions between cows and good emotional state of the herd but there was a negative association with good health assessed through the occurrence of diseases and injuries. These opposite associations resulted in no association with the overall welfare of the herd. Milk yield should not therefore be used as an indicator of overall welfare.