Search results for "VEGETATION"
showing 10 items of 1069 documents
Multiple sediment proxies from Jaraguá cave, Brazil
2019
Multiple paleoclimate, paleovegetation and paleoenvironmental records from Jaraguá cave, located at center of South America. In this dataset that covers the last 28,000 year is included δ13C and δ18O values and 87Sr/86Sr ratios in stalagmites combined with XRF-derived elemental chemistry, δ13Corg, total organic carbon and total inorganic carbon (carbonate) in a sedimentary profile from the same cave.
Crop type and altitude are the main drivers of species composition of arable weed vegetation in Tajikistan
2015
Summary The influence of broad-scale environmental factors on the species composition of segetal weed communities in Tajikistan was investigated. The research was conducted throughout the country, analysing plots of root crops as well as cereals from all phytogeographical regions of Tajikistan, with the exception of the eastern Pamir. The study was based on 440 phytosociological relevees sampled between 2009 and 2013 and analysed using direct and indirect ordinations. A set of environmental variables was obtained for each plot: altitude, mean annual precipitation, mean annual temperature, pH, crop type, longitude, latitude and date of sampling (seasonality). Crop type was the major factor d…
Contents of free amino acids in needles of Norway Spruce trees in relation to novel forest decline. Studies on trees from a site in the northern Blac…
1993
The free amino acid content in needles of Norway spruce trees (about 45-year-old) was determined by means of HPLC. The studied trees have been growing at a forestry site in the Black Forest which is characterized by a high impact of ozone and magnesium deficiency. Measurements were carried out on visibly healthy and on damaged trees on several dates during two vegetation periods and during the course of a day. The amino acids occurring at the highest concentrations were glutamate, arginine, aspartate, and glutamine. The typical seasonal changes in the content of free amino acids, with their minimum during summer, were disturbed in the needles of the damaged trees. Particularly in summer and…
Bacterial communities in Arctic fjelds of Finnish Lapland are stable but highly pH-dependent
2007
The seasonal and spatial variations of microbial communities in Arctic fjelds of Finnish Lapland were studied. Phospholipid fatty acid analysis (PLFA) and terminal restriction fragment analysis (T-RFLP) of amplified 16S rRNA genes were used to assess the effect of soil conditions and vegetation on microbial community structures along different altitudes of two fjelds, Saana and Jehkas. Terminal restriction fragments were additionally analysed from c . 160 cloned sequences and isolated bacterial strains and matched with those of soil DNA samples. T-RFLP and PLFA analyses indicated relatively similar microbial communities at various altitudes and under different vegetation of the two fjelds. …
Pedogenesis in disturbed alpine soils (NW Italy)
2002
In alpine environments, natural or man-induced disturbances are fairly common and acknowledged as determining factors in pedogenesis and soil distribution. We have selected a representative alpine valley in the Italian Northwestern Alps to evaluate the effects of perturbations of different intensity and frequency on soil development and weathering during the last few centuries. In order of decreasing disturbances, we selected: (i) an active avalanche shoot; (ii) a man-built terrace; (iii) a park-like forest; and (iv) a coniferous forest. In the two most disturbed sites, independently of the intensity and frequency of the disturbances, the active pedogenic processes are restricted to the top…
Effect of climate and vegetation on soil organic carbon, humus fractions, allophanes, imogolite, kaolinite, and oxyhydroxides in volcanic soils of Et…
2007
A soil sequence along an elevational gradient ranging from subtropical to subalpine climate zones in the Etna region (Sicily, southern Italy) was investigated with respect to organic C, kaolinite, and crystalline to noncrystalline Al and Fe phases. Special emphasis was given to the stabilization of soil organic carbon (SOC) and its interaction with the inorganic phases. The soils were variations of Vitric Andosols that developed on a trachy-basaltic lava flow with an age of 15,000 years. Two main vegetation systems dominated the sites: at the lower sites, it was mainly maquis vegetation and, at the higher elevated sites, predominantly coniferous forest. The concentration of SOC in the topso…
Carbon decomposition of the topsoils and soil fractions under forest and pasture in the western Brazilian Amazon basin, Rondonia
2000
The topsoils of two sites, comprising natural forest and 4- and 20-year-old pastures, respectively, were selected in Rondonia to evaluate the changes of soil organic matter due to pasture establishment. These changes were evaluated by measuring the proportions of the C and N associated with clay and silt fractions, and by the C decomposition (CD) rate of the whole topsoils and their size fractions. The topsoils studied had large proportions of C and N associated with fine fractions, especially with clay fractions. The CD rate of the silt fractions was higher than that of the clay fractions under the two forest topsoils and under the 20-year-old pasture. The CD rate of the silt fractions und…
Organic matter dynamics and aggregation in soils under rain forest and pastures of increasing age in the eastern Amazon Basin
1997
Abstract In the eastern Amazon basin, four neighbouring clayey Oxisols with similar particle-size distributions were selected, one under rain forest and three under pasture for 7, 12 and 17 years, respectively. These soils were sampled at depth intervals of 0.1 m down to 1 m. Although no clear effect of pasture establishment on aggregate stability was assessed, significant negative effects of cattle trampling on porosity and water retention and of vegetation change on clay water-dispersion were observed in the organic-rich horizons (0–0.40 m layers). Indirect evidence of a great change of the nature of organic materials was also suggested, particularly with (i) an increase in both negative …
Berberido aetnensis-Crataegion laciniatae, new orophilous pre-forestal alliance of the class Rhamno-Prunetea
2011
In this paper the results of a phytosociological study carried out on some aspects of shrub vegetation of forest margins are presented, investigated in the higher belt of the Madonie Mts. (Northern-Central Sicily), referred to the order Prunetalia spinosae (Rhamno-Prunetea). Through comparison with other known coenoses in the central- southern part of the Italian Peninsula and in Sicily – especially, the associations of Berberidion vulgaris and those of Pruno-Rubion ulmifolii – a coenological and phytogeographical autonomy has been made evident and has resulted in the recognition of a new alliance, described under the name Berberido aetnensis-Crataegion laciniatae Gianguzzi et al., all. nov…
Evaluation of remote sensing of vegetation fluorescence by the analysis of diurnal cycles
2008
Chlorophyll fluorescence (ChF) emission is a direct indicator of the photosynthetic activity of vegetation, which is a key parameter of the carbon cycle. This paper analyses chlorophyll fluorescence evolution at leaf level during a complete diurnal cycle in simulated and natural conditions, for two species under different stress conditions. Absolute spectral radiance of the ChF emission is obtained allowing a quantitative derivation of the fluorescence yield of the ChF, which correlates well with established fluorescence instruments. The studied cases show that the ChF emission is mainly driven by the photosynthetic active radiation during the whole cycle, but the fluorescence yield is seve…