Search results for " Forest"
showing 10 items of 1940 documents
Age and spatial structure of natural Pinus sylvestris stands in Latvia
2005
Abstract The age and spatial structure of six natural old growth Pinus sylvestris stands in Latvia were investigated, to attempt to identify retrospectively the past features of development. In each stand, one or two plots of size 200–900 m2 were established. Tree locations were mapped, stem diameter was measured, and tree age was determined from cores or by counting branch whorls. Tree distribution was assessed by Ripley's K function. A clumped spatial pattern was shown for P. sylvestris younger than 100 years. The temporal patterns of establishment could be partly linked to favourable climatic periods. The major disturbance affecting pine stands along the coast was windblown sand, which p…
Comparison of Crop Trait Retrieval Strategies Using UAV-Based VNIR Hyperspectral Imaging.
2021
Hyperspectral cameras onboard unmanned aerial vehicles (UAVs) have recently emerged for monitoring crop traits at the sub-field scale. Different physical, statistical, and hybrid methods for crop trait retrieval have been developed. However, spectra collected from UAVs can be confounded by various issues, including illumination variation throughout the crop growing season, the effect of which on the retrieval performance is not well understood at present. In this study, four retrieval methods are compared, in terms of retrieving the leaf area index (LAI), fractional vegetation cover (fCover), and canopy chlorophyll content (CCC) of potato plants over an agricultural field for six dates duri…
Special Issue: Water Management Strategies in Irrigated Areas
2016
The 2015 edition of the United Nations World Water Development Report highlighted that ‘water is at the core of sustainable development’. Water has upgraded the quality of human life, and any progress to achieve a more sustainable world will deal with the maintenance and/or the improvement of water management. Water demand has grown at more than twice the population rate in the XX century. By 2025, it is estimated that about 1.8 billion people will live in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions.
Nutrient removal by rice–wheat cropping system as influenced by crop establishment techniques and fertilization options in conjunction with microbial…
2020
AbstractNutrient uptake by the rice–wheat cropping system (RWCS) is an important indicator of soil fertility and plant nutrient status. The hypothesis of this investigation was that the rate and sources of nutrient application can differentially influence nutrient removal and soil nutrient status in different crop establishment techniques (CETs). Cropping system yield was on par in all the CETs evaluated, however, there were significant changes in soil nutrient availability and microbiological aspects. The system nitrogen (N), phosphorus (P), potassium (K) and zinc (Zn) uptake in aerobic rice system followed by zero tillage wheat (ARS-ZTW) was 15.7–17.6 kg ha−1, 0.7–0.9 kg ha−1, 7–9.8 kg ha…
Effects of tilling methods on soil penetration resistance, organic carbon and water stable aggregates in a vineyard of semiarid Mediterranean environ…
2018
Tillage, especially in semiarid Mediterranean environment, enhances the mineralization process of soil organic matter (SOM) and, in turn, decreases aggregate stability. Furthermore, continuous tillage leads to the formation of plough pan beneath the tilled layer. In the present study, we investigated the effect of an innovative self-propelled machine (spading machine, SM) for shallow tillage on SOM, water stable aggregates (WSA) and soil penetration resistance (PR). Such effects were compared to those of chisel plough (CP), rotary tiller (RT) and no tillage (NT). Each tilling method was applied up to a depth of 15 cm, whereas in NT only a brush cutter was used for weed control. Soil analyse…
Differential toxicity of simazine and diuron to Torilis arvensis and Lolium rigidum
1990
Summary: In a soil application, Torilis arvensis was nearly as susceptible as Lolium rigidum to simazine but was 18-fold more tolerant to diuron. Treat ment with diuron inhibited photosynthesis in L. rigidum but had only a limited effect in T. arvensis although chloroplasts isolated from both species displayed similar susceptibility. 14C-diuron degradation in plants was limited, with the formation of conjugates of mono-methyl-diuron in T. arvensis and N-dealkylated derivatives of diuron in L. rigidum. 14C-diuron entered the roots and was translocated throughout the leaves of L. rigidum but was restricted to stems, leaf petioles and leaf veins of T. arvensis. This difference in transport pat…
Influence of plant traits, soil microbial properties, and abiotic parameters on nitrogen turnover of grassland ecosystems
2016
International audience; Although it is known that multiple interactions among plant functional traits, microbial properties , and abiotic soil parameters influence the nutrient turnover, the relative contribution of each of these groups of variables is poorly understood. We manipulated grassland plant functional composition and soil nitrogen (N) availability in a multisite mesocosm experiment to quantify their relative effects on soil N turnover. Overall, root traits, arbuscular mycorrhizal colonization, denitrification potential, as well as N availability and water availability, best explained the variation in measured ecosystem properties, especially the trade-off between nutrient sequest…
Les phénols de la lignine et le 13C, traceurs de l'origine des matières organiques du sol
2001
Abstract In spodosols of Gascony (France), conversion of maritime pine stands into maize cropping leads to an incorporation of maize organic matter, which changed the isotopic (δ13C) and phenolic signature in A and L horizons of soil. Hydrolysis of phenol lignin in forests and cultivated soils showed the predominance of vanillic units under forest and the early but moderate incorporation of cinnamic acids. Incorporation of syringic units appeared higher, related to a large maize production of stable syringic phenols. Syringic units represented a long-term marker of maize inputs in soils, whereas vanillic units revealed the degradation of forest organic matter.
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Growth and water relations of field-grown ‘Valencia’ orange trees under long-term partial rootzone drying
2017
Climate, soil water potential (SWP), leaf relative water content (RWC), stem water potential (WPstem), stomatal conductance (g s), trunk, shoot and fruit growth of ‘Valencia’ orange trees were monitored during five consecutive seasons (2007–2012) to study water status and growth responses to irrigation placement or volume. 48 adult trees were exposed to conventional irrigation (CI, 100% of crop evapotranspiration on both sides of the rootzone), partial rootzone drying (PRD, 50% of CI water only on one alternated side of the rootzone) and continuous deficit irrigation (DI, 50% of CI water on both sides of the rootzone). Reducing irrigation volumes by 55% (DI) over CI increased leaf water def…