The ratio of microcharcoal to phytolith content in soils as a new proxy of fire activity

The Holocene ◽  
2020 ◽  
Vol 30 (11) ◽  
pp. 1567-1578
Author(s):  
Mengdan Wen ◽  
Rencheng Li ◽  
Richard S. Vachula ◽  
Xiude Wang ◽  
Yang Qin ◽  
...  

Microcharcoal in soils and sediments is an ideal proxy for studying fire activity. Phytoliths in soils and sediments record the environmental conditions in which the phytoliths were formed by plants. However, our understanding of the relationships between fire activity, plant communities, and the preservation of microcharcoal and phytoliths in soils and sediments remains limited. In this study, we collected soils and sediments across a gradient of burned and unburned forest in southwest China, and analyzed the microcharcoals and phytoliths in these samples to understand the relationships between these microfossils (ratios of microcharcoal to phytolith particles (Ch/Ph)), fire activity, and vegetation cover. We show that the Ch/Ph ratios recorded fire activity and were significantly different across the gradient of burned to unburned forest. The highest and lowest ratios (0.25 and 0.01) were found in burned forest (Bs1) and unburned forest samples (Us2), respectively. The ratios gradually decreased with increasing distance from the fire. This study suggests the ratio (Ch/Ph) to be a useful proxy for studying fire activity and/or history using soils and sediments.

Author(s):  
M. I. Dzhalalova ◽  
A. B. Biarslanov ◽  
D. B. Asgerova

The state of plant communities in areas located in the Tersko-Sulak lowland was studied by assessing phytocenotic indicators: the structure of vegetation cover, projective cover, species diversity, species abundance and elevated production, as well as automated decoding methods. There are almost no virgin soils and natural phytocenoses here; all of them have been transformed into agrocenoses (irrigated arable lands and hayfields, rice-trees and pastures). The long-term impact on pasture ecosystems of natural and anthropogenic factors leads to significant changes in the indigenous communities of this region. Phytocenoses are formed mainly by dry-steppe types of cereals with the participation of feather grass, forbs and ephemera, a semi-desert haloxerophytic shrub - Taurida wormwood. At the base of the grass stand is common coastal wormwood and Taurida wormwood - species resistant to anthropogenic influences. Anthropogenic impacts have led to a decrease in the number of species of feed-rich grain crops and a decrease in the overall productivity of pastures. Plant communities in all areas are littered with ruderal species. The seasonal dynamics of the land cover of the sites was estimated by the methods of automatic decoding of satellite images of the Landsat8 OLI series satellite for 2015, dated by the periods: spring - May 20, summer - July 23, autumn - October 20. Satellite imagery data obtained by Landsat satellite with a resolution in the multispectral image of 30 m per pixel, and in the panchromatic image - 10 m per pixel, which correspond to the requirements for satellite imagery to assess the dynamics of soil and vegetation cover. Lower resolution data, for example, NDVI MODIS, does not provide a reliable reflection of the state of soil and vegetation cover under arid conditions. In this regard, remote sensing data obtained from the Internet resource https://earthexplorer.usgs.gov/ was used.


1995 ◽  
pp. 58-66
Author(s):  
N. M. Kalibernova

The fragment of the legend of the map concerning the vegetation of flood- plains and river-valleys in the subzones of northern and southern deserts is presented in the article. The map is compiled in Department of Vegetspon Geography and Cartography of Komarov Botanical Institute by a large team of botanists-geographers of the former USSR. The nature environments determining the development of vegetation of river-valleys in arid climate are conditioned by the intrazonal factors (alluvial and flood processes) at the background of natural zonal factors. Contrasts of environments and corresponding plant communities manifest themselves first of all. Mineralization of ground waters, salinity of soils, including the alluvial ones, are of essential importance. The practice of vegetation mapping of unstable habitats, to which floodplain landscapes belong, has shown that units of phytocoenological classification is of little use for this purpose. The heterogeneity of vegetation, consisting of short-term unstable serial communities generates a need for typification of space combinations of such phytocoenoses. For this purpose it is convenient to use generalized ecological-dinamic series, including plant communities of all levels within the limits of definite segment of valley. These series are the mapping units on the map. The vegetation of the first terrace is also nessecary to include in a single series with flood-plain vegetation because it has supplementary influence of ground waters. The higher divisions of the legend are based on zonal characters: vegetation of valleys in northern, middle and southern deserts. 13 numbers are used to show the vegetation cover of flood-plains and valleys. Additional 7 numbers are used for the out-of-valley meadow vegetation. The content is enriched by using of the letters by the numbers showing the geographic variants of series and ciphers for combination of series and out-of-series communities. The text legend is supplemented by the matrix (table), showing the subordination of subtitles, zonal position and geographic distribution of divisions. The types of series in the matrix are listed with indication of the main dominant species that gives the additional information on the legend divisions. The author's conclusion is that valley vegetation reveals clearly the zonal features, correlating with zonal (desert) vegetation.


2021 ◽  
Vol 124 ◽  
pp. 107393
Author(s):  
Ying Deng ◽  
Ming Wang ◽  
Rasoul Yousefpour ◽  
Marc Hanewinkel

2014 ◽  
Vol 2 (4) ◽  
pp. 13-20 ◽  
Author(s):  
Jolanta Pełka-Gościniak

Abstract The geological structure and the occurrence of mineral resources in the Silesian Upland in a significant way influenced the development of industry and caused transformation of every landscape element, among others changes in relief and therefore the formation of anthropogenic landforms. The paper focuses on environmental aspects of relief transformation in the Silesian Upland. The author described aesthetic, geomorphological, hydrological, climatological, pedological and biological aspects on the base of representatives of two groups of landforms–consciously created by human being and being an unintentional effect of human activity (of secondary character). All analysed landforms are new elements in relief, in majority of cases being in disharmony with their neighbourhood. They are alien to the landscape and disturb the equilibrium in the nature. It was proved that they strongly influence water and climatological conditions and soil cover. But sometimes the anthropogenic landforms can be perceived as advantageous for the nature, especially in case of subsidence depressions because of development of aquatic and hydrophilous species and in case of spoil tips due to spontaneous development of vegetation cover. The nature easily adapts to new environmental conditions (process of natural succession and independent introduction of species for new habitats). In these terrains the increase in biodiversity was observed.


2014 ◽  
Vol 6 (3) ◽  
pp. 288-291
Author(s):  
Cipran BÎRSAN ◽  
Ana COJOCARIU ◽  
Elena CENUŞĂ

Although Clathrus archeri is a widely spread species in the Western Europe, in Romania it is considered a rare species, identified from only eight sites. In July 2013, it was found in two new sites from Gurghiu and Bârgău Mountains, in the Romanian Eastern Carpathians. This paper presents a detailed description of the new recorded specimens and of the habitat where this fungus was found. Plant communities where Clathrus archeri was recorded belong to the “mountain hay meadows” habitat type (Festuco rubrae - Agrostietum capillaris community). Taking into consideration the previous published data, the comparison with other habitats types in which this species occurs suggests that Clathrus archeri has no special preferences for certain environmental conditions.


Ecography ◽  
2020 ◽  
Vol 43 (10) ◽  
pp. 1464-1474
Author(s):  
Nicola J. Day ◽  
Alison L. White ◽  
Jill F. Johnstone ◽  
Geneviève É. Degré‐Timmons ◽  
Steven G. Cumming ◽  
...  

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