Temperature sensitivity of soil organic matter decomposition—what do we know?

Soil organic matter (SOM) represents one of the largest reservoirs of carbon on the global scale. Thus, the temperature sensitivity of bulk SOM and of different SOM fractions is a key factor determining the response of the terrestrial carbon balance to climatic warming. We condense the available knowledge about the potential temperature sensitivity and the actual temperature sensitivity of decomposition in situ, which ultimately depends on substrate availability. We review and evaluate contradictory results of estimates of the temperature sensitivity of bulk SOM and of different SOM fractions. The contradictory results demonstrate a need to focus research on biological and physicochemical controls of SOM stabilisation and destabilisation processes as a basis for understanding strictly causal relationships and kinetic properties of key processes that determine pool sizes and turnover rates of functional SOM pools. The current understanding is that temperature sensitivity of SOM mineralisation is governed by the following factors: (1) the stability of SOM, (2) the substrate availability, which is determined by the balance between input of organic matter, stabilisation and mineralisation of SOM, (3) the physiology of the soil microflora, its efficiency in substrate utilisation and its temperature optima and (4) physicochemical controls of destabilisation and stabilisation processes, like pH and limitation of water, oxygen and nutrient supply. As soil microflora is functionally omnipotent and most SOM is of high age and stability, the temperature dependence of stable SOM pools is the central question that determines C stocks and stock changes under global warming.     

Clinical evaluation of pimecrolimus eye drops for treatment of canine keratoconjunctivitis sicca: a comparison with cyclosporine A

The aim of this study was to evaluate the efficacy of pimecrolimus oil-based eye drops in alleviating the clinical signs of keratoconjunctivitis sicca (KCS) in dogs and to compare the efficacy with that of cyclosporine A (CsA) ointment. An open-label, multicenter study enrolling 44 dogs previously untreated with CsA was conducted. Dogs were randomly assigned to a treatment group and medicated twice daily for 8 weeks. After that time the mean increase (+/-SEM) in the Schirmer tear test was 9.2+/-1.6 mm/min in the pimecrolimus group and 5.8+/-1.1 mm/min in the CsA group (P=0.085). The improvement in clinical signs of inflammation in eyes treated with pimecrolimus was significantly greater than in eyes treated with CsA (P=0.02). The results show that 1% pimecrolimus oily eye drops are as safe as and more effective than CsA ointment in controlling KCS in dogs.     

D-Lactic acidosis in calves

Metabolic acidosis has long been known as a frequent and potentially severe complication of neonatal calf diarrhoea. It has also been described in 'acidosis-without-dehydration' syndrome in calves and was suspected to occur during ruminal drinking. Clinical signs of central nervous impairment, particularly changes in behaviour and posture, progressing to coma and recumbency, were originally attributed to this metabolic disturbance. The loss of bicarbonate in the faeces was regarded as the main cause of acidosis in this context. During the past decade, however, evidence has accumulated that d-lactic acidosis is a more common occurrence in calves with neonatal diarrhoea. The most probable source of D-lactataemia is bacterial fermentation of undigested substrate that reaches the large intestine due to damage to small intestinal mucosal epithelium. Recent research has shown that most of the clinical signs that were formerly attributed to acidosis were in fact due to elevated blood levels of D-lactate. The aim of this review is to provide a current overview of d-lactic acidosis.     

Economic benefits of large-scale remediation of contaminated marine sediments—a literature review and an application to the Grenland fjords in Norway

Purpose  

As input to a cost-benefit analysis of large-scale remediation measures of contaminated sediments in the Grenland fjords in Norway, we conducted a contingent valuation (CV) survey of a representative sample of households from municipalities adjacent to these fjords.     

Application of mycorrhizal roots improves growth of tropical tree seedlings in the nursery: a step towards reforestation with native species in the Andes of Ecuador

Most tree species in tropical mountain rain forests are naturally associated with arbuscular mycorrhizal fungi. Previous studies in southern Ecuador of 115 tree species revealed that only three species were not associated with arbuscular mycorrhizal fungi. Seedlings of tropical tree species raised in the nursery may need to be associated with arbuscular mycorrhizal fungi to survive transplantation shock in higher numbers. Methods for establishing plantations with native tree species are not yet established for Ecuador. Thus, we investigated the feasibility of using mycorrhizal roots of seedlings of Inga acreana, Tabebuia chrysantha, Cedrela montana and Heliocarpus americanus that had trapped mycorrhizal fungi from forest humus in the nursery to inoculate C. montana and H. americanus with native arbuscular mycorrhizal fungi. Inoculation with either a mixture of mycorrhizal roots from the four species or only with mycorrhizal roots from the same tree species were compared with effects of moderate fertilization. Assessment of plant growth and mycorrhizal status of 6-months-old Cedrela montana and Heliocarpus americanus revealed an improvement in growth and diverse associated fungi through mycorrhizal root inoculation in comparison with moderate fertilization. Moderate fertilization did not suppress mycorrhization.     

Impact of topography on cross-pollination in maize (Zea mays L.)

Understanding cross-pollination is important to achieve the coexistence of genetically modified (GM) and conventional maize (Zea mays L.); it is still not known whether topography favors or hinders cross-pollination. In 2005 and 2006, the effect of gradients of 3.4–6.8° on cross-pollination was investigated in the canton of Zurich, Switzerland. Cross-pollination was revealed by the presence of yellow-grains on a white-grain hybrid at distances up to 17.5 m from the yellow-grain pollen donor hybrid. The measurements of the inclination of the slope were based on aerial images data taken by an unmanned GPS/INS (Global Positioning System/Inertial Navigation System)-based and stabilized model helicopter, which delivered precise altitude-based data for sampling points at tassel height.The rate of cross-pollination increased significantly with decreasing altitude of the receptor field (r = 0.36–0.64). However, the effect seems to be weaker than that of other factors like wind direction and velocity.     

GIS Coop: networks of silvicultural trials for supporting forest management under changing environment

Key message

The diversity of forest management systems and the contrasted competition level treatments applied make the experimental networks of the GIS Coop, a nationwide testing program in the field of emerging forestry topics within the framework of the ongoing global changes.

Context

To understand the dynamics of forest management systems and build adapted growth models for new forestry practices, long-term experiment networks remain more crucial than ever.

Aims

Two principles are at the basis of the experimental design of the networks of the Scientific Interest Group Cooperative for data on forest tree and stand growth (GIS Coop): contrasted and extreme silvicultural treatments in diverse pedoclimatic contexts.

Methods

Various forest management systems are under study: regular and even-aged stands of Douglas fir, sessile and pedunculate oaks, Maritime and Laricio pines, mixed stands of sessile oak, European silver fir, and Douglas fir combined with other species. Highly contrasted stand density regimes, from open growth to self-thinning, are formalized quantitatively.

Results

One hundred and eighty-five sites representing a total of 1206 plots have been set up in the last 20 years, where trees are measured regularly (every 3 to 10 years). The major outputs of these networks for research and management are the calibration/validation of growth and yield models and the drawing up of forest management guides.

Conclusion

The GIS Coop adapts its networks so that they can contribute to develop growth models that explicitly integrate pedoclimatic factors and thus also contribute to research on the sustainability of ecosystems under environmental and socio-economic changes.

     

Early selection for resistance to <Emphasis Type="Italic">Heterobasidion parviporum</Emphasis> in Norway spruce is not likely to adversely affect growth and wood quality traits in late-age performance

Infections with Heterobasidion parviporum devalue the Norway spruce timber as the decayed wood does not meet the necessary quality requirements for sawing. To evaluate the incorporation of disease resistance in the Norway spruce breeding strategy, an inoculation experiment with H. parviporum on 2-year-old progenies of 466 open-pollinated families was conducted under greenhouse (nursery) conditions. Lesion length in the phloem (LL), fungal growth in sapwood (FG) and growth (D) were measured on an average of 10 seedlings for each family. The genetic variation and genetic correlations between both LL, FG and growth in the nursery trial and wood quality traits measured previously from 21-year old trees in two progeny trials, including solid-wood quality traits (wood density, and modulus of elasticity) and fiber properties traits (radial fiber width, tangential fiber width, fiber wall thickness, fiber coarseness, microfibril angle and fiber length). For both LL and FG, large coefficients of phenotypic variation (>?26%) and genetic variation (>?46%) were detected. Heritabilities of LL and FG were 0.33 and 0.42, respectively. We found no significant correlations between wood quality traits and growth in the field progeny trials with neither LL nor FG in the nursery trial. Our data suggest that the genetic gains may reach 41 and 52% from mass selection by LL and FG, respectively. Early selection for resistance to H. parviporum based on assessments of fungal spread in the sapwood in nursery material, FG, will not adversely affect growth and wood quality traits in late-age performance.     

Recent growth changes in Western European forests are driven by climate warming and structured across tree species climatic habitats

Key message

Recent growth changes (1980–2007) in Western European forests strongly vary across tree species, and range from +42% in mountain contexts to ?17% in Mediterranean contexts. These changes reveal recent climate warming footprint and are structured by species' temperature (?) and precipitation (+) growing conditions.

Context

Unprecedented climate warming impacts forests extensively, questioning the respective roles of climatic habitats and tree species in forest growth responses. National forest inventories ensure a repeated and spatially systematic monitoring of forests and form a unique contributing data source.

Aims

A primary aim of this paper was to estimate recent growth changes in eight major European tree species, in natural contexts ranging from mountain to Mediterranean. A second aim was to explore their association with species’ climatic habitat and contemporary climate change.

Methods

Using >315,000 tree increments measured in >25,000 NFI plots, temporal changes in stand basal area increment (BAI) were modelled. Indicators of climate normals and of recent climatic change were correlated to species BAI changes.

Results

BAI changes spanned from ?17 to +42% over 1980–2007 across species. BAI strongly increased for mountain species, showed moderate/no increase for generalist and temperate lowland species and declined for Mediterranean species. BAI changes were greater in colder/wetter contexts than in warmer/drier ones where declines were observed. This suggested a role for climate warming, further found more intense in colder contexts and strongly correlated with species BAI changes.

Conclusion

The predominant role of climate warming and species climatic habitat in recent growth changes is highlighted in Western Europe. Concern is raised for Mediterranean species, showing growth decreases in a warmer climate with stable precipitation.