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.     

Concept and feasibility study for the integrated evaluation of environmental monitoring data in forests

In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis (crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative, as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.

Improving the design of long-term monitoring experiments in forests: a new method for the assessment of local soil variability by combining infrared spectroscopy and dendrometric data

Key message

Near- and mid-infrared spectroscopy allows for the detection of local patterns of forest soil properties. In combination with dendrometric data, it may be used as a prospective tool for determining soil heterogeneity before setting up long-term forest monitoring experiments.

Context

Forest soils and stands generally exhibit higher spatial heterogeneity than other terrestrial ecosystems. This variability needs be taken into account before setting up long-term forest monitoring experiments to avoid multiple interactions between local heterogeneity and the factors tested in the experiment.

Aims

We hypothesized that raw near- and mid-infrared spectra can be used as an integrated proxy of a large set of soil properties. The use of this method, in combination with dendrometric data, should provide a quick and cost-effective tool for optimizing the design of experimental forest sites.

Methods

We assessed the local soil heterogeneity at 11 experimental sites in oak and beech stands, which belong to a new forest long-term ecological research (LTER) network. We used near- and mid-infrared spectroscopy in soil and litter samples. The spectra were subjected to principal components analyses (PCA) to determine the intra-site variability of the soil and litter layers.

Results

Based on mapped PCA coordinates and basic dendrometric data, it was possible to design the experiment and minimize the interactions between the treatment layout and the tested variables. The method was validated with chemical analyses of the soil. No interaction was detected at the set-up of the experiment between the treatment layout and chemical soil properties (C, N, C/N ratio, pH, CEC, Al, Mg, P₂O₅, Fe, Mn, Na, and K).

Conclusion

Near-infrared (NIR) and mid-infrared (MIR) spectroscopy is a useful tool for characterizing the overall heterogeneity of soil chemical properties. It can be used without any preliminary calibration. In combination with dendrometric data, it provides a reliable method for optimizing LTER plots in different types of ecosystems.

     

Relationship between leaf apoplast pH and iron chlorosis of sunflower (Helianthus annuus L.)

A hypothesis has been presented and tested that bicarbonate (HCO₃) and nitrate (NO₃) are the most important anions inducing iron (Fe) chlorosis because these anions increase the pH of leaf apoplast which in turn depresses ferric‐iron [Fe(III]) reduction, and hence, the uptake of Fe into the symplasm. Experiments with young sunflower (Helianthus annuus) plants showed that nutrition with NO₃ as the sole nitrogen (N) source induced chlorosis whereas ammonium nitrate (NH₄NO₃) did not. Monohydrogen carbonate (bicarbonate) also favoured the development of chlorosis. The degree of chlorosis was not related to the Fe concentration in the leaves. Both anion species, NO₃ and HCO₃, increased the pH of the leaf apoplast which was measured by means of the fluorescence dye 5‐carboxyfluorescein. A highly significant negative correlation between leaf apoplast pH and chlorophyll concentration in the leaves (r = ‐0.97) was found. Ferric‐Fe reduction in the apoplast—measured by means of ferrocene—provided evidence that a low leaf apoplast pH, obtained with ammonium (NH₄) supply, favoured the reduction of Fe(III) as compared with a higher leaf apoplast pH obtained with NO₃ supply. These results support the hypothesis tested.     

Pattern recognition of geophysical data

A new rock classification method for ground penetrating radar (GPR) data is presented for cases where no additional geological information is available from boreholes. There are non-linear relationships between petrophysical properties of rocks and electromagnetic waves which can be handled using two methods derived from statistical learning theory on pattern recognition. An investigation was carried out looking at proving the feasibility of the method in principle for use on synthetic models as well as measurement data. The different learning methods were also compared.The method is based on multivariate statistical learning algorithms for the discrimination of layer boundaries between different rocks. The discrimination developed works with artificial neural networks (ANN) and support vector machines (SVM). The processing procedure starts with geological models with varying petrophysical rock parameters, which are to be sought in the measurement data. The models are used to generate synthetic radargrams from which rock properties can be derived using wave attributes. The calculated values of the wave attributes are stored in a multivariate data pool. This data pool is used to train the ANN and the SVM. The same wave attributes are derived from the GPR data and also saved in a data pool. This generates two data sets for pattern recognition with which to directly classify rock layers. Wave attributes can therefore be used to derive the non-linear correlative relationships between rock properties and GPR data by the weighted matrices of ANN and SVM.The presented method can be used to match reflections in the GRR data directly with the layer boundaries of rock formations. The classification of a boundary horizon between rock salt and anhydrite is demonstrated on synthetic GPR traces and measurement data from a rock salt mine. The advantage of this method is that rock classification is not a priori dependent on borehole data.     

Zum jahreszeitlichen Nitratgehalt und zur Nitratauswaschung von landwirtschaftlich genutzten Böden in Baden-Württemberg

Seasonal nitrate content in, and nitrate leaching from, agricultural soils of Baden-Wuerttemberg The behavior of soil nitrate was investigated at five field locations in the State of Baden-Wuerttemberg between 1984 and 1987. It was found that the amount of nitrate in the upper 90 cm of soil was not a constant, but fluctuated throughout the year with maxima in the spring and in the fall. Additionally, it was found that the amount of nitrate leaching during winter (from November through April) was correlated to, but not identical with the mineral nitrogen content of the previous fall. It further appeared that nitrate leaching in light sandy soils is mainly a mixing process, whereas in heavy soils it seems to be more a miscible displacement phenomenon.     

Multi-element analysis of an english peat bog soil

Nineteen elements were quantitatively determined by atomic emission spectroscopy with inductively coupled plasma in peat profiles in Ringinglow Bog, Derbyshire, England. For the elements Ba, Ca, Cd, Co, Cr, Fe, La, Mn, Ni, Ti, and Zn an enrichment in the upper 5 cm of the peat bogs was found probably caused by anthropogenic influences. The elements Al, Be, Cu, and Pb showed a different distribution pattern with maximum concentration in the 5 to 15 cm layer. The elements Mg, Na, and Sr showed no enrichment in the upper 55 cm of the peat reflecting the constant input of these elements from the sea during the last few centuries. Upper parts (leaves and stems) of the plants investigated (Calluna vulgaris and Eriophorum vaginatum) only represent higher values of Pb compared with the normal element content in other plants. Compared with the results of peat profiles in a Norwegian bog, the concentrations of the comparable elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) are much higher in the English peat. Ringinglow Bog seem to be very suitable for further investigations within the scope of a global monitoring programme.     

A conceptual framework for damage compensation schemes

Damage compensation schemes are widely used to mitigate human-wildlife conflicts. Despite the growing relevance of such conflicts, a theoretical framework to analyze the cost-effectiveness of damage compensation schemes is still missing. The article aims to fill this gap by proposing a conceptual framework by categorizing cost categories, which can be used to compare different types of compensation schemes. To demonstrate the value of the framework, we present an example that compares ex-post compensation and compensation in advance in the European otter (Lutra lutra) in the Upper Lusatia, Germany. We find that the two types of schemes differ widely in their transaction costs. Transaction costs themselves are closely related to the temporal and spatial distribution of damages. Therefore, the choice between the two types of compensation schemes depends on the distribution of damages, which itself depends on the species under concern. Based on this, we recommend a compensation-in-advance type of damage compensation scheme for the otter in the Upper Lusatia, Germany.     

Impact of treated wastewater irrigation on water repellency of Mediterranean soils

Irrigation with treated wastewater (TWW) is gaining importance due to declining water availability in dry regions. TWW irrigation has various potential adverse effects on soil quality such as hydrophobic effects on soil surfaces, reducing initial sorptivity and promoting the formation of preferential flow paths. In May and June 2010, in situ infiltration measurements using mini disk tension infiltrometer were deployed in five different orchard plots in Israel to assess the impact of different irrigation water qualities on the soil water repellency index R. In most plantations, long-term test sites were accessed to compare adjacent plots irrigated with fresh water (FW) or TWW. Topsoil samples were analyzed for selected physical and chemical characteristics. The mean R values increased at all TWW sites, from +15 up to +55 % compared with FW sites. The water drop penetration time (WDPT) increased up to 30 fold at three of five TWW sites compared with FW sites. Subsequent U tests and multilevel analysis indicated an impact of the type of irrigation water on R and WDPT. Moreover, soil electrical conductivity and exchangeable sodium percentage were consistently higher at all TWW sites. These results show that irrigation water quality clearly influences physical and chemical properties of the soil.