Virtual trees and light capture: a method for optimizing agroforestry stand design

In agroforestry systems, the distribution of light transmitted under tree canopies can be a limiting factor for the development of intercrops. The light available for intercrops depends on the quantity of light intercepted by tree canopies and, consequently, on the architecture of the tree species present. The influence of tree architecture on light transmission was analysed using dynamic 3D architectural models. The architectural analysis of Acacia mangium and Tectona grandis was performed in Indonesian agroforestry systems with trees aged from 1 to 3 years. 3D virtual trees were then generated with the AmapSim simulation software and 3D virtual experiments in which tree age, planting density, planting pattern and pruning intensity varied were reconstructed in order to simulate light available for the crop. Canopy closure of trees was more rapid in A. mangium than in T. grandis agroforestry systems; after 3 years the quantity of light available for A. mangium intercrops was three times lower than under T. grandis. Simulations with A. mangium showed that practices such as pruning and widening tree spacing enable to increase the total transmitted light within the stand. On T. grandis, modification of the tree row azimuth resulted in changes in the spatial and seasonal distribution of light available for the intercrops. These results are discussed in terms of agroforestry system management.

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.

     

Polycyclic Aromatic Hydrocarbon Oxidation from Concentrates Issued from an Attrition Process of Polluted Soil Using the Fenton Reagent and Permanganate

This study was conducted to determine the optimal conditions for PAH degradation from highly contaminated attrition sludge (PAC) using a Fenton process or successive permanganate (KMnO₄) oxidation and Fenton processes. The following parameters were studied to optimize the Fenton oxidation process: the amounts of reactants based on the stoichiometric oxidant demand (SOD), the reactant addition protocol and number of doses, and the solid/liquid ratio (S/L). The results showed that the following conditions were optimum: TS?=?30%, 7.5 times SOD, H₂O₂/Fe²⁺ ratio?=?10, and added five times during 60 min, which allowed the degradation of 43% of total 27 PAHs from the PAC. Successive Fenton and KMnO₄ oxidation processes were also tested. PAH degradation using a sequential Fenton process followed by KMnO₄ oxidation (or KMnO₄ followed by Fenton) was higher than for the use of Fenton or KMnO₄ treatment alone. Up to 71% of the total 27 PAHs were degraded when using a combination of both processes. It appeared that the sequential treatment is a viable method for the significant degradation of 27 PAHs from PAC (t value?>?2.77).     

Mortality of silver fir and Norway Spruce in the Western Alps — a semi-parametric approach combining size-dependent and growth-dependent mortality

Question

Tree mortality can be modeled using two complementary covariates, tree size and tree growth. Tree growth is an integrative measure of tree vitality while tree diameter is a good index of sensitivity to disturbances and can be considered as a proxy for tree age which may indicate senescence. Few mortality models integrate both covariates because classical model calibration requires large permanent plot data-sets which are rare. How then can we calibrate a multivariate mortality model including size and growth when permanent plots data are not available?

Location

To answer this question, we studied Abies alba and Picea abies mortality in the French Swiss and Italian Alps.

Method

Our study proposes an alternative semi-parametric method which includes a random sample of living and dead trees with diameter and growth measurements.

Results

We were able to calibrate a mortality model combining both size-dependent and growth-dependent mortality. We demonstrated that A. alba had a lower annual mortality rate (10%) than P. abies (18%) for low growth (< 0.2 mmyear^?1). We also demonstrated that for higher diameters (DBH ≥ 70 cm), P. abies had a higher mortality rate (0.45%) than A. alba (0.32%).

Conclusion

Our results are consistent with the mechanisms of colonization-competition trade-off and of successional niche theory which may explain the coexistence of these two species in the Alps. The method we developed should be useful for forecasting tree mortality and can improve the efficiency of forest dynamics models.     

Study of an Amphoteric Surfactant in a Soil Decontamination Process Using ANS Enhanced Fluorescence: Micellar Behavior and Dosing in Synthetic and Soil Solutions

Cocamidopropyl hydroxysultaine (CAS) has been used in a pilot plant study as a biodegradable surfactant for the extraction of polycyclic aromatic hydrocarbons (PAHs) and lead (Pb) from contaminated soils. The soil treatment has been done in flotation cells with a concentration of 0.20 g CAS L⁻¹ in saline conditions (3 M NaCl) and using a pulp density of 20% (w/w). The process integrates the recirculation of the liquid phases separated from the soil by centrifugation or filtration. Thus, it was necessary to understand CAS-PAHs micellar behavior and to follow the behavior and the fate of the surfactant in the process. 1-8-anilino-naphthalene sulfonate (ANS) is used as a fluorophor compound in the ANS enhanced fluorescence technique. A three-dimensional model detailing the change in the micellar behavior at high NaCl concentration and at different pH has been established. Fluorescence results of centrifuged soil matrix containing CAS have been compared to the results from synthetic solutions assays. A method allowing an accurate titration of the CAS has been developed by using the exact same matrix of the soil as the tested samples for the preparation of the calibration curves. The study of the surfactant concentration in the process has been performed and allows the adjustment of the CAS concentration in the recirculated water.     

Environmental drivers of community diversity in a neotropical urban landscape: a multi-scale analysis

Context

Many aquatic communities are linked by the aerial dispersal of multiple, interacting species and are thus structured by processes occurring in both the aquatic and terrestrial compartments of the ecosystem.

Objectives

To evaluate the environmental factors shaping the aquatic macroinvertebrate communities associated with tank bromeliads in an urban landscape.

Methods

Thirty-two bromeliads were georeferenced to assess the spatial distribution of the aquatic meta-habitat in one city. The relative influence of the aquatic and terrestrial habitats on the structure of macroinvertebrate communities was analyzed at four spatial scales (radius = 10, 30, 50, and 70 m) using redundancy analyses.

Results

We sorted 18,352 aquatic macroinvertebrates into 29 taxa. Water volume and the amount of organic matter explained a significant part of the taxa variance, regardless of spatial scale. The remaining variance was explained by the meta-habitat size (i.e., the water volume for all of the bromeliads within a given surface area), the distance to the nearest building at small scales, and the surface area of buildings plus ground cover at larger scales. At small scales, the meta-habitat size influenced the two most frequent mosquito species in opposite ways, suggesting spatial competition and coexistence. Greater vegetation cover favored the presence of a top predator.

Conclusions

The size of the meta-habitat and urban landscape characteristics influence the structure of aquatic communities in tank bromeliads, including mosquito larval abundance. Modifications to this landscape will affect both the terrestrial and aquatic compartments of the urban ecosystem, offering prospects for mosquito management during urban planning.

     

MOTOR AND SENSORY NERVE CONDUCTION STUDY IN THE FERRET

Ferrets are considered a popular small mammal pet, and like other companion animals they are reported to suffer from diseases affecting the neuromuscular system. There currently is a lack of comprehensive electrodiagnostic study regarding the appendicular nerves of ferrets. In this research investigation, 25 domestic ferrets were used for electromyography and motor nerve conduction studies of the tibial, fibular, ulnar, and radial nerves, including H reflexes of the tibial and ulnar nerves, as well as sensory conduction of the fibular nerve. Mean and standard deviations for motor and sensory nerve studies were established. The hypothesis that weight would be correlated with all distal and proximal compound muscle action potential latencies was tested and confirmed for the tibial, fibular, and radial nerves but not the ulnar nerve.     

Fagacées: a tree-centered growth and yield model for sessile oak (<Emphasis Type="Italic">Quercus petraea</Emphasis> L.) and common beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

• Introduction  

Fagacées is a growth model that has been developed for pure Oak or Beech stand management in even-aged high forests and coppice with standards forests. It has been calibrated for the plain forests of northern France.     

A non-destructive method for testing two components of the behaviour of soil-applied agricultural chemicals over a long period

BACKGROUND: Owing to the complexity of soil composition, accurate predictions of both apoplastic systemicity of lipophilic xenobiotics and their leaching from the soil are made difficult. Therefore, a non‐destructive method to assess directly these two components of the spatial behaviour of soil‐applied phytochemicals is needed. RESULTS: The plant selected was a dwarf tomato, which can exude an abundant apoplastic fluid through large stomata for several months. The feasibility and reliability of the method were assayed using three triazoles exhibiting different log D values. HPLC‐MS analyses indicated that triadimenol (log D = 2.97) was clearly the most mobile compound within the apoplast, especially its diastereoisomer A. Propiconazole (log D = 3.65) and penconazole (log D = 4.64) exhibited a similar low systemicity. The data remained the same when the three fungicides were applied together on the soil. Long time‐course studies (1.5 months) of penconazole behaviour indicated that, in contrast to leaching, which decrease sharply, root‐to‐shoot translocation remained almost unchanged during the whole experiment, in spite of the high lipophilicity of this fungicide. CONCLUSION: This method must contribute to a better knowledge of the behaviour of commercial soil‐applied phytochemicals. It can also be used to screen new xenobiotics within strategies to satisfy environmental requirements. Copyright © 2011 Society of Chemical Industry     

Isolation and characterisation of a bacterial strain degrading the herbicide sulcotrione from an agricultural soil

BACKGROUND: The dissipation kinetics of the herbicide sulcotrione sprayed 4 times on a French soil was studied using a laboratory microcosm approach. An advanced cultivation‐based method was then used to isolate the bacteria responsible for biotransformation of sulcotrione. Chromatographic methods were employed as complementary tools to define its metabolic pathway. RESULTS: Soil microflora was able quickly to biotransform the herbicide (DT₅₀ ≈ 8 days). 2‐Chloro‐4‐mesylbenzoic acid, one of its main metabolites, was clearly detected. However, no accelerated biodegradation process was observed. Eight pure sulcotrione‐resistant strains were isolated, but only one (1OP) was capable of degrading this herbicide with a relatively high efficiency and to use it as a sole source of carbon and energy. In parallel, another sulcotrione‐resistant strain (1TRANS) was shown to be incapable of degrading the herbicide. Amplified ribosomal restriction analysis (ARDRA) and repetitive extragenic palendromic PCR genomic (REP‐PCR) fingerprinting of strains 1OP and 1TRANS gave indistinguishable profiles. CONCLUSION: Sequencing and aligning analysis of 16S rDNA genes of each pure strain revealed identical sequences and a close phylogenetic relationship (99% sequence identity) to Pseudomonas putida. Such physiological and genetic properties of 1OP to metabolise sulcotrione were probably governed by mobile genetic elements in the genome of the bacteria. Copyright © 2011 Society of Chemical Industry