Relation between sandbar mode and vegetation expansion in sand-bed river

2014 ◽  
pp. 429-435 ◽  
Author(s):  
Y Toda ◽  
S Kim ◽  
T Tsujimoto ◽  
N Sakai
Keyword(s):  
Vegetation Expansion

Effect of patches of woody vegetation on the role of fire in tropical grasslands and savannas

2014 ◽  
Vol 23 (3) ◽  
pp. 410 ◽  
Author(s):  
Frank van Langevelde ◽  
Casper de Groot ◽  
Thomas A. Groen ◽  
Ignas M. A. Heitkönig ◽  
Ian Gaigher
Keyword(s):  
Patch Size ◽  
Fire Effects ◽  
Climatic Conditions ◽  
Windward Side ◽  
Woody Vegetation ◽  
Leeward Side ◽  
Tree Seedlings ◽  
Tropical Grasslands ◽  
Vegetation Expansion

In tropical grasslands and savannas, fire is used to reduce woody vegetation expansion. Woody vegetation in these biomes is often patchily distributed, and micro-climatic conditions can largely vary locally with unknown consequences for fire effects. We hypothesised that (1) fire has higher temperature and maintains high temperatures for a longer period at the windward side than at the leeward side of wooded patches, (2) this difference increases with patch size, (3) fire has a larger effect on woody vegetation at the windward side than at the leeward side of wooded patches and (4) this effect increases with patch size. We planted tree seedlings around wooded patches in a grassland and burnt these plots. We found that fire had a lower temperature and had an elevated temperature for a shorter time period at the leeward side of wooded patches than at the windward side. Also, we found smaller effect of fire on the seedlings at the leeward side. We conclude that patches of woody vegetation can have a large effect on the role of fire in tropical grasslands and savannas. This effect suggests a ‘safe zone’ for seedlings at the leeward side, which consequently promotes woody vegetation expansion. This paper contributes to understanding of the effect of patchiness of woody vegetation on the role of fire in tropical grasslands and savannas in reducing woody vegetation expansion.

The role of a non-native tree in riparian vegetation expansion and channel narrowing along a dryland river

Ecohydrology ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. e1988 ◽  
Author(s):  
Michael L. Scott ◽  
Lindsay V. Reynolds ◽  
Patrick B. Shafroth ◽  
John R. Spence
Keyword(s):  
Riparian Vegetation ◽  
Channel Narrowing ◽  
Native Tree ◽  
Dryland River ◽  
Vegetation Expansion

scholarly journals Small Ruminants Grazing as a Rehabilitative Land Management Tool in the Negev Highland; Soil, Geomorphological and Topographical Perspectives

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1730
Author(s):  
Amir Mor-Mussery ◽  
Hiam Abu-Glion ◽  
Shimshon Shuker ◽  
Eli Zaady
Keyword(s):  
Organic Matter ◽  
Land Management ◽  
Management Practice ◽  
Small Ruminants ◽  
Clay Content ◽  
Management Tool ◽  
Vegetation Growth ◽  
Land Management Practice ◽  
Seasonal Flood ◽  
Vegetation Expansion

The ‘wadis’ (ephemeral incised channels in arid regions) concern badlands with low agriculture utilisation that expands to neighbouring cultivated areas. They are noticeable and unique landforms characterised by vegetation patches and seasonal flood flows with scenic beauty that must be conserved. The wadi characteristics have influenced the way of life of their indigenous residents from ancient times until now. The main one is grazing with small ruminants (SR). The authorities and public consider grazing in these areas as a destructive land management practice that should be reduced. To assess the viability of grazing in such regions, we hypothesised that fluvial and biological flows tightly correlate with the wadis’ landforms, channels and slopes. The site of study is located in the Yeroham mountains nearby the Rahma planned Bedouin village. Five different transects of channels and slopes were located over representative wadis, including those exposed to grazing. The finding indicates that a herbaceous vegetation expansion uphill was observed only in grazed transects, while the wadi slope patterns affect its patterns. It contains an increased soil water content (from a similar value of 5% until 13% change in the grazed transect), 1.5% higher soil organic matter, 0.08 mg Kg−1 higher Nitrite content and 1–2% higher clay content in the grazed transects, up to 4 m ahead from the channel. The novelty of this finding suggested that the SR influences the organic matter to reach the wadi channel and facilitate the adherence of aggregated clay and the formed colluvial layer that serves as a substrate to the expanded vegetation growth. Adequate implementation of these grazing patterns may rehabilitate degraded ‘wadis’ and increase their tourism eligibility.

scholarly journals Efficacy of eastern Australian rainforests and topography as fire refugia under anthropogenic climate change

2021 ◽  
Author(s):  
Myles Jay Bennell ◽  
Philip Le C. Stewart ◽  
Patrick T. Moss
Keyword(s):  
Climate Change ◽  
Ecosystem Services ◽  
Fire Frequency ◽  
Climate Feedback ◽  
Burn Severity ◽  
Future Research ◽  
Feedback Systems ◽  
High Severity ◽  
Eastern Australia ◽  
Vegetation Expansion

Abstract Background: The 2019-20 Australian bushfire season was the most environmentally detrimental bushfire season on record. The extreme heat and drought exposed normally fire-resistant communities to uncharacteristically dry fuel loads and abnormally high severity burning. In eastern Australia this included mesic rainforest environments (including the World Heritage listed Gondwana Rainforests of Australia), which are often highly sensitive to fire, contain high biodiversity values, are critical habitat for threatened species, embody distinct endemism, provide valuable ecosystem services and are critical for terrestrial carbon storage. East coast rainforests are also highly fragmented, with less than half of pre-European levels remaining. Increases in fire frequency and intensity associated with climate change may threaten these already fragmented rainforest environments. This study considers the efficacy of rainforest refugia under a heightened bushfire climate, via spatial analysis of burn extent, burn severity and topographic characteristics for rainforests during the 2019-20 bushfire season within the Eastern Australian Temperate and Subtropical Forests Conservation Management Zone.Results: Burn severity, vegetation and elevation datasets were merged and analysed across mid-eastern Australia. A significant portion of rainforest was fire affected across the study area (~17%), with ~5% burnt to a high or very high severity. Elevation, topographic position (i.e. valleys), slope and aspect all contributed to maintaining rainforest fire refugia. The study resulted in a mapping product that can be utilised by researchers and protected area managers to locate and assess burnt rainforest in mid-eastern Australia.Conclusions: This study enables the identification of rainforest fire refugia and threatened rainforest communities for future research and conservation efforts in eastern Australia. The results also demonstrate the potential of climate change to enact widespread rainforest declines, with potentially dire consequences for biodiversity and ecosystem services. This event and recurrent fire events may enact positive climate feedback systems by enabling pyrophytic vegetation expansion and converting rainforest carbon pools into a carbon source.

Biogeochemical Characteristics of Lacustrine Sediments Reflecting a Changing Alpine Neotropical Ecosystem during the Pleistocene

2002 ◽  
Vol 58 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Germán Mora ◽  
Lisa M. Pratt ◽  
Arnoud Boom ◽  
Henry Hooghiemstra
Keyword(s):  
Algal Blooms ◽  
Lacustrine Sediments ◽  
Organosulfur Compounds ◽  
Alpine Ecosystems ◽  
Tropical Andes ◽  
Isotopic Signatures ◽  
Climatic Variations ◽  
Lacustrine Deposits ◽  
Reducing Conditions ◽  
Vegetation Expansion

AbstractContinuous lacustrine deposits of the Funza-II core from the Bogotá basin, Colombia (5°N74°W) record late Pleistocene climatic variations, providing an opportunity to assess the influence of glacial–interglacial climate changes on alpine ecosystems in equatorial South America. Biogeochemical response of this tropical alpine system to climate change was inferred from changes in elemental concentrations and ratios and isotopic signatures in the upper 120 m of the lacustrine Funza core.Values of δ13Corg exhibit eight abrupt, positive shifts that are thought to reflect rapid expansions of C4 grasses in the tropical Andes and algal blooms. One of these excursions, interpreted to correspond to C4 vegetation expansion, occurred in sediments accumulated during the last glaciation (∼30,000–50,000 yr B.P.) and implies a downslope shift of the upper Andean treeline, regardless of prevailing temperatures.Sedimentary carbon/sulfur ratios are low and indicate significant sequestering of sulfur. Monosulfides are the dominant constituent of sedimentary sulfur during relatively humid intervals, when increased supply of iron caused by enhanced weathering favored the formation of monosulfide minerals under strongly reducing conditions. In contrast, organosulfur compounds dominate the sedimentary sulfur-species in relatively drier intervals when mildly reducing conditions and limited iron input promoted the diagenetic incorporation of sulfur in organic matter. Dry events inferred from the sulfur record typically correlate with glacial maxima, whereas glacial terminations are usually associated with wet periods.

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