Comparison of nearest neighbour approaches for small area estimation of tree species-specific forest inventory attributes in central Europe using airborne laser scanner data

The three nonparametric k nearest neighbour (kNN) approaches, most similar neighbour inference (MSN), random forests (RF) and random forests based on conditional inference trees (CF) were compared for spatial predictions of standing timber volume with respect to tree species compositions and for predictions of stem number distributions over diameter classes. Various metrics derived from airborne laser scanning (ALS) data and the characteristics of tree species composition obtained from coarse stand level ground surveys were applied as auxiliary variables. Due to the results of iterative variable selections, only the ALS data proved to be a relevant predictor variable set. The three applied NN approaches were tested in terms of bias and root mean squared difference (RMSD) at the plot level and standard errors at the stand level. Spatial correlations were considered in the statistical models. While CF and MSN performed almost similarly well, large biases were observed for RF. The obtained results suggest that biases in the RF predictions were caused by inherent problems of the RF approach. Maps for Norway spruce and European beech timber volume were exemplarily created. The RMSD values of CF at the plot level for total volume and the species-specific volumes for European beech, Norway spruce, European silver fir and Douglas fir were 32.8, 80.5, 99.0, 137.0 and 261.1%. These RMSD values were smaller than the standard deviation, although Douglas fir volume did not belong to the actual response variables. All three non-parametric approaches were also capable of predicting diameter distributions. The standard errors of the nearest neighbour predictions on the stand level were generally smaller than the standard error of the sample plot inventory. In addition, the employed model-based approach allowed kNN predictions of means and standard errors for stands without sample plots.     

Bacterial salt tolerance is unrelated to soil salinity across an arid agroecosystem salinity gradient

In arid and semi-arid ecosystems, salinization is a major threat to the productivity of agricultural land. While the influence of other physical and chemical environmental factors on decomposer microorganisms have been intensively studied in soil, the influence of salinity has been less exhaustively assessed. We investigated the influence of soil salinity on soil bacterial communities in soils covering a range of salt levels. We assessed tolerance of the bacterial communities from Libyan agricultural soils forming a salinity gradient to salt (NaCl), by extracting bacterial communities and instantaneously monitoring the concentration-response to added NaCl with the Leucine incorporation technique for bacterial growth. To maximise our ability to detect differences in bacterial salt tolerance between the soils, we also repeated the assessment of bacterial growth tolerance after one month incubation with 1 or 2% added organic matter additions to stimulate microbial growth levels. We could establish clear concentration-response relationships between bacterial growth and soil salinity, demonstrating an accurate assessment of bacterial tolerance. The in situ soil salinity in the studied soils ranged between 0.64 and 2.73 mM Na (electrical conductivities of 0.74-4.12 mS cm⁻¹; cation exchange capacities of 20-37 mmol_c kg⁻¹) and the bacterial tolerance indicated by the concentration inhibiting 50% of the bacterial growth (EC₅₀) varied between 30 and 100 mM Na or between electrical conductivities of 3.0 and 10.7 mS cm⁻¹. There was no relationship between in situ soil salinity and the salt tolerance of the soil bacterial communities. Our results suggest that soil salinity was not a decisive factor for bacterial growth, and thus for structuring the decomposer community, in the studied soils.     

Effects of aspect and altitude on carbon cycling processes in a temperate mountain forest catchment

Context

Varying altitudes and aspects within small distances are typically found in mountainous areas. Such a complex topography complicates the accurate quantification of forest C dynamics at larger scales.

Objectives

We determined the effects of altitude and aspect on forest C cycling in a typical, mountainous catchment in the Northern Limestone Alps.

Methods

Forest C pools and fluxes were measured along two altitudinal gradients (650–900 m a.s.l.) at south-west (SW) and north-east (NE) facing slopes. Net ecosystem production (NEP) was estimated using a biometric approach combining field measurements of aboveground biomass and soil CO₂ efflux (SR) with allometric functions, root:shoot ratios and empirical SR modeling.

Results

NEP was higher at the SW facing slope (6.60?±?3.01 t C ha^?1  year^?1), when compared to the NE facing slope (4.36?±?2.61 t C ha^?1 year^?1). SR was higher at the SW facing slope too, balancing out any difference in NEP between aspects (NE: 1.30?±?3.23 t C ha^?1 year^?1, SW: 1.65?±?3.34 t C ha^?1 year^?1). Soil organic C stocks significantly decreased with altitude. Forest NPP and NEP did not show clear altitudinal trends within the catchment.

Conclusions

Under current climate conditions, altitude and aspect adversely affect C sequestering and releasing processes, resulting in a relatively uniform forest NEP in the catchment. Hence, including detailed climatic and soil conditions, which are driven by altitude and aspect, will unlikely improve forest NEP estimates at the scale of the studied catchment. In a future climate, however, shifts in temperature and precipitation may disproportionally affect forest C cycling at the southward slopes through increased water limitation.

     

Assessment of the diversity of comfrey (Symphytum officinale L. and S. × uplandicum Nyman)

Genetic Resources and Crop Evolution - Comfrey Symphytum officinale L. (true comfrey) and S.?×?uplandicum Nyman (a hybrid between S. asperum Lepech?×?S. officinale...     

Effect of grazing intensity and soil characteristics on soil organic carbon and nitrogen stocks in a temperate long-term grassland

The effects of different grazing pressures (GPs) on soil properties are not sufficiently understood. The objectives were to analyse the effects of three different extensive GPs on stocks of soil organic C and total N, soil microbial biomass C, basal respiration and mineral N in three different soil depths of a long-term pasture in Central Germany (FORBIOBEN field trial). No significant (p ≤ 0.05) effects of GP on weighted stocks of soil organic C, total N, soil microbial biomass C, mineral N and basal respiration rate were observed, suggesting that the C and N cycles are coupled in the three grazing treatments. Oxalate soluble Fe contents explained a marked part of the variation of soil organic C (multiple linear regression: R² = 0.64) and total N contents (R² = 0.64) in the soils, whereas almost all of the variability of soil microbial biomass C contents and basal respiration was explained by soil organic C contents. Overall, variabilities of soil organic C and N contents were largely explained by oxalate soluble Fe contents, whereas grazing intensity did not affect the C and N dynamics.     

Krachtvoer: effect evaluation of a Dutch healthful diet promotion curriculum for lower vocational schools

OBJECTIVE: The aim of this study was to assess the behavioural effects of a school-based healthful diet promotion intervention implemented in lower vocational schools. DESIGN: A cluster-randomised pre-test-post-test experimental design was used, and data were collected by means of written questionnaires. SETTING: Students of 18 Dutch lower vocational schools. SUBJECTS: The final sample consisted of 10 experimental schools with 13 teachers, 37 classes and 879 students, and eight control schools with 10 teachers, 31 classes and 734 students (total n = 1613). RESULTS: Fixed regression analyses revealed beneficial effects on the behavioural measures relating to fruit intake (as assessed by a food frequency measure and fruit consumption during the previous day), and most behavioural measures related to high-fat snack intake (food frequency measure, and number of snacks and total fat intake from snacks during the previous day). The behavioural effects relating to breakfast habits were limited. Some positive behavioural effects occurred in the total target population, others mainly or only among students with more unfavourable intakes at baseline. Mixed regression analysis found comparable regression coefficients for the behavioural outcomes, but the effects related to fruit intake were no longer statistically significant. CONCLUSIONS: Although we did not find the expected effects on all outcome indicators, the total pattern of results suggest that Krachtvoer offered a surplus value over existing curricula. However, some programme elements need to be revised to improve effectiveness and prevent negative effects, and more information is needed about the long-term effects of the programme.     

Application of gypsum and lime to increase cation adsorption of a Geric Ferralsol in the Brazilian Amazon region

A Brazil-nut plantation 140 km east of Manaus was the site of a 3-month field trial, in which a by-product gypsum and a lime were compared. The soil properties in the plantation, 23 years after slash-and-burn, are not basically different from the remaining primary forest. The comparison is impeded by a distinct spatial variability of the soil nutrient content within the plantation. A linkage between Effective Cation Exchange Capacity (ECEC) and sulfate content of the soil is presumed. Gypsum-application increases the exchangeable Ca considerably, which is not an effect of Al-exchange, but of newly created adsorption sites. The potential of gypsum to increase the ECEC corresponds on a 1:1 basis with the potential for sulfate adsorption in the soil. Mg and nitrate are strongly leached after gypsum application. The applied, extremely fine ground lime has almost no effects below 5—10 cm depth. Ca, Mg and, to a lesser extent, K exhibit a much enhanced adsorption when applied as sulfate instead of chloride. All three cations are preferentially adsorbed in the subsoil, where the ECEC is only half the value of the upper soil. For fertilization concepts of those soils, the subsoil deserves much greater attention. The infiltration pattern of an organic dye gives evidence of a strong influence of bypass water flow through macropores in the soil.     

Evaluation of glucose metabolism in three horses with lower motor neuron degeneration

OBJECTIVES: To determine whether increased glucose metabolism is the potential cause of the decreased plasma glucose curve determined after oral glucose tolerance testing in horses with lower motor neuron degeneration. ANIMALS: 3 horses with signs suggestive of lower motor neuron degeneration, 1 horse with malignant melanoma with multiple metastases, and an obese but otherwise healthy horse. Procedures-Glucose metabolism was assessed by use of the hyperglycemic clamp and euglycemic hyperinsulinemic clamp techniques. RESULTS: Mean rate of glucose metabolism of horses with lower motor neuron degeneration was significantly greater (mean, 3.7 times greater than control horses; range, 2.1 to 4.8 times greater) than that reported in 5 healthy control horses (41 +/- 13 micromol/kg/min vs 11 +/- 4.5 micromol/kg/min, respectively). In addition, one of the affected horses, an 8-year-old warmblood gelding, had a 5.6-times increased sensitivity to exogenously administered insulin, compared with that reported in 5 healthy control horses. Pancreatic insulin secretion was not insufficient in horses with lower motor neuron degeneration. Findings in the 2 diseased control horses were unremarkable. CONCLUSIONS AND CLINICAL RELEVANCE: Increased glucose metabolism in horses with lower motor neuron degeneration may be the cause of the decreased plasma glucose curve detected after oral glucose tolerance testing. This finding could aid in developing supportive treatments with respect to adequate glucose and vitamin E supplementation.     

Ilyonectria palmarum sp. nov. causing dry basal stem rot of Arecaceae

During surveys conducted in 2010–2013, a complete breakage or bending of the trunk and a dry basal stem rot were observed on containerised Brahea armata, B. edulis, Howea forsteriana and Trachycarpus princeps plants in different nurseries located in eastern Sicily (southern Italy). A cylindrocarpon-like species was consistently obtained from diseased palm tissues, while known pathogens of these hosts such as Ganoderma, Phytophthora and Thielaviopsis were not found associated with symptomatic tissues or isolated on standard or selective media. A total of 40 cylindrocarpon-like isolates were collected and characterised based on morphology and DNA phylogeny. Multigene analyses based on the β-tubulin, histone H3, translation elongation factor 1-α, and the internal transcribed spacers (ITS1, 5.8S, ITS2) genes facilitated the identification of a new species, described here as Ilyonectria palmarum. The pathogenicity of one representative isolate collected from each palm species was tested on plants cultivated under nursery conditions and in a growth chamber. All isolates were pathogenic to B. armata, B. edulis, H. forsteriana, and T. princeps and symptoms identical to that observed in nurseries were reproduced. Dry basal stem rot and stem bending caused by Ilyonectria palmarum represents a potentially serious problem for nurseries cultivating containerised palms.