Search results for "Forestry"

On the hidden significance of differing micro-sites on tree-ring based climate reconstructions

2015

Tree-ring chronologies are commonly extended back in time by combining samples from living trees with relict material preserved in man-made structures or natural archives (e.g. lakes). Although spatially close, these natural archives and living-tree-sites often comprise different micro-climates. Inhomogeneous growth conditions among these habitats, which may yield offsets in growth-rates, require caution in data processing. Here we assess species-specific growth dynamics in two micro-habitats and their potential effects on long chronologies by combining tree-ring data from different living-tree-sites with an “artificial” subfossil dataset. Well replicated (n > 80) Norway spruce (…

Testing steady-state analysis of single-ring and square pressure infiltrometer data

2016

Testing reliability of the saturated soil hydraulic conductivity, Ks, estimated by applying the steady-state single-ring (SR) model to the quasi steady-state infiltration rates obtained with a single-ring pressure infiltrometer (PI) increases confidence in the estimated Ks values. Determining a means to estimate Ks from infiltration data collected with a square infiltrometer allows the use of sources of different shapes. Using numerically simulated infiltration rates for six homogeneous soils ranging in texture from sand to silty clay loam, this investigation suggested an overall good performance of the SR model, with estimated Ks values differing by not more than 25% from the true values f…

Advances in designing drip irrigation laterals

2018

It is known that using paired laterals, in which two distribution pipes extend in opposite directions from a common manifold, contribute to increasing water use efficiency (WUE). Recently, an analytical procedure to optimally design paired drip laterals on uniform slopes was proposed. More recently, this design procedure was simplified by deriving simple explicit relationships, as a function of 16 calibration constants, with relative errors that were less than 2%. In this paper, further simple design relationships are derived that require only 3 calibration constants, thus more readily obtainable results are produced and the influence of the flow rate and diameter exponents of resistance eq…

Contrasting Norway spruce disturbance dynamics in managed forests and strict forest reserves in Slovakia

2022

Abstract Forest disturbances are intensifying globally, yet regional drivers of these dynamics remain poorly understood. We investigated recent disturbance intensities in Norway spruce (Picea abies L.) forests in Slovakia (Central Europe) with different management objectives in 2000–2017 based on Landsat imagery. We focused on 122 strict reserves without any management, their actively managed surroundings (500 m and 2000 m buffers), and managed production forests beyond the buffer areas. We used generalized additive mixed models to test for differences in temporal trends of disturbance intensity among these management categories. We found that disturbance intensity was increasing in all man…

Social media e pubblica amministrazione. Una rassegna

2015

Negli ultimi vent’anni i processi di cambiamento strutturale a cui sono state indotte – o, in altri casi, a cui si sono strategicamente dedicate - le organizzazioni sono stati molteplici. Cause fra le più diverse hanno determinato, più o meno direttamente, effet-ti di ricombinazione delle funzioni interne alle stesse organizzazioni da parte degli atto-ri che le popolano, ovvero di una vera e propria nuova strutturazione, in ragione di mutate caratteristiche dell’ambiente in cui esse operano, di mutati e più stringenti vin-coli economici dentro i quali muoversi rispetto al passato anche recente e, nel caso di quelle che producono beni o servizi direttamente destinati ad una clientela o ad un…

Estimation of pulp yield in industrial oxygen-alkali delignification of softwood kraft pulp

2002

Fate of Oxygen in Industrial Oxygen-Alkali Delignification of Softwood Kraft Pulp

2004

CHEMICAL PULPING. Oxidative degradation of AOX in softwood-based kraft mill effluents from E C F bleachin g

2012

Abstract Softwood-based kraft mill bleaching effluents from the initial bleaching stages D0 and E1 (the bleaching sequence being D0E 1D 1 E2D2) were treated by the oxidative Fenton method (H20rFeS04) to decompose organic pollutants contammg adsorbable organic halogens (AOX). Experiments designed using the Taguchi method were applied to predict the process conditions that would result in a cost-effective and adequate removal of AOX. In addition to the composition and concentration of the reagents (H202 and Fe2+), the main process parameters selected were temperature and reaction time, while pH was adj usted to an approximate value of 4 (the volumetric ratio of the mixed effluents D0:E 1 was …

Thermochemical behavior of Norway spruce ( Picea abies ) at 180-225 °C

2002

Norway spruce (Picea abies) was heated for 2–8 h in the temperature range 180–225 °C, under a steam atmosphere. The chemical analyses of the treated feedstock samples indicated that during heating (total mass loss 1.5–12.5% of the initial DS) carbohydrates (hemicelluloses and cellulose) were clearly more amenable to various degradation reactions than lignin. In addition, major water-soluble products released from the feedstock material during the treatments were classified into several compound groups and changes in the relative mass portion of these groups were monitored by GC during a separate experiment.

Plant diversity enhances the natural attenuation of polycyclic aromatic compounds (PAHs and oxygenated PAHs) in grassland soils

2019

Increasing plant species richness stimulates microbial activity in soil, which might favor biodegradation of polycyclic aromatic compounds (PACs). To explore the relationship between plant community composition and PACs in grassland soils (Fluvisols exposed to an urban atmosphere), we determined the concentrations of 29 polycyclic aromatic hydrocarbons (PAHs) and 15 oxygenated PAHs (OPAHs) in topsoils of 80 plots of a grassland biodiversity experiment. The plots included different levels of plant species richness (1, 2, 4, 8, 16, 60 species) and 1–4 plant functional groups (grasses, small herbs, tall herbs, and legumes) in a randomized block design. The concentrations (ng g−1) of ∑29PAHs an…