scholarly journals Large herbivores maintain a two‐phase herbaceous vegetation mosaic in a semi‐arid savanna

2019 ◽  
Vol 9 (22) ◽  
pp. 12779-12788 ◽  
Author(s):  
David J. Augustine ◽  
Benjamin J. Wigley ◽  
Jayashree Ratnam ◽  
Staline Kibet ◽  
Moses Nyangito ◽  
...  
Keyword(s):  
Herbaceous Vegetation ◽  
Two Phase ◽  
Large Herbivores ◽  
Semi Arid ◽  
Vegetation Mosaic

Effects of grazing on patch structure in a semi‐arid two‐phase vegetation mosaic

2005 ◽  
Vol 16 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Pablo A. Cipriotti ◽  
Martin R. Aguiar
Keyword(s):  
Two Phase ◽  
Patch Structure ◽  
Semi Arid ◽  
Vegetation Mosaic

scholarly journals Large herbivores may alter vegetation structure of semi-arid savannas through soil nutrient mediation

Oecologia ◽  
2011 ◽  
Vol 165 (4) ◽  
pp. 1095-1107 ◽  
Author(s):  
Cornelis van der Waal ◽  
Ada Kool ◽  
Seline S. Meijer ◽  
Edward Kohi ◽  
Ignas M. A. Heitkönig ◽  
...  
Keyword(s):  
Vegetation Structure ◽  
Soil Nutrient ◽  
Large Herbivores ◽  
Semi Arid

scholarly journals Livestock redistribute runoff and sediments in semi-arid rangeland areas

Solid Earth ◽  
2015 ◽  
Vol 6 (2) ◽  
pp. 433-443 ◽  
Author(s):  
P. Sarah ◽  
M. Zonana
Keyword(s):  
Sediment Yield ◽  
Overland Flow ◽  
Arid Areas ◽  
Mosaic Pattern ◽  
Two Phase ◽  
Surface Patches ◽  
Sediment Deposits ◽  
Three Phase ◽  
Almost All ◽  
Semi Arid

Abstract. Semi-arid areas where grazing is the main land use exhibit a "three-phase-mosaic" pattern of dominant surface patches: shrubs, trampling routes, and intershrub areas. This pattern differs from the "two-phase mosaic" seen in grazing-free semi-arid areas. The patches might create a positive feedback process in which enhanced infiltration beneath shrubs minimizes overland flow from under their canopies, thereby strengthening the sink–source mechanism by which overland flow generated between shrubs rapidly infiltrates into the soil beneath them, where it deposits soil particles, litter, nutrients and organic matter, thereby enhancing infiltration by changing the local microtopography, and improving soil properties. To analyze sink–source relationships among the patches in grazed areas in rangelands of the semi-arid northern Negev region of Israel, we constructed small runoff plots, 0.25–1.0 m2 in area, of five types: shrub (Sarcopoterium spinosum), intershrub, route, route–shrub combination, and intershrub–shrub combination. The shrubs always occupied the downslope part of the plot. Overland flow and sediment deposits were measured in all plots during 2007/8 and 2008/9. The combined plots yielded much less overland flow and sediments than intershrub, routes and shrub ones, indicating that the shrubs absorbed almost all the yields of the upper part of their plots. The shrubs generated less runoff and sediments than routes and intershrubs; runoff flows from the routes and intershrubs were similar; sediment yield was highest in the intershrubs. Thus, runoff yield exhibited a two-phase mosaic pattern, and sediment yield, i.e., soil erosion, a three-phase mosaic pattern.

scholarly journals Interactions between large herbivores and litter removal by termites across a rainfall gradient in a South African savanna

2011 ◽  
Vol 27 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Robert Buitenwerf ◽  
Nicola Stevens ◽  
Cleo M. Gosling ◽  
T. Michael Anderson ◽  
Han Olff
Keyword(s):  
Plant Biomass ◽  
Spatial Scales ◽  
Landscape Scale ◽  
Local Scale ◽  
Arid Ecosystems ◽  
Annual Rainfall ◽  
Large Herbivores ◽  
Mammalian Herbivores ◽  
Litter Removal ◽  
Semi Arid

Abstract:Litter-feeding termites influence key aspects of the structure and functioning of semi-arid ecosystems around the world by altering nutrient and material fluxes, affecting primary production, foodweb dynamics and modifying vegetation composition. Understanding these complex effects depends on quantifying spatial heterogeneity in termite foraging activities, yet such information is scarce for semi-arid savannas. Here, the amount of litter that was removed from 800 litterbags in eight plots (100 litterbags per plot) was measured in Hluhluwe–iMfolozi Park (HiP) South Africa. These data were used to quantify variation in litter removal at two spatial scales: the local scale (within 450-m2 plots) and the landscape scale (among sites separated by 8–25 km). Subsequently, we attempted to understand the possible determinants of termites’ foraging patterns by testing various ecological correlates, such as plant biomass and bare ground at small scales and rainfall and fences that excluded large mammalian herbivores at larger scales. No strong predictors for heterogeneity in termite foraging intensity were found at the local scale. At the landscape scale termite consumption depended on an interaction between rainfall and the presence of large mammalian herbivores: litter removal by termites was greater in the presence of large herbivores at the drier sites but lower in the presence of large herbivores at the wetter sites. The effect of herbivores on termite foraging intensity may indicate a switch between termites and large herbivore facilitation and competition across a productivity gradient. In general, litter removal decreased with increasing mean annual rainfall, which is in contrast to current understanding of termite consumption across rainfall and productivity gradients. These results generate novel insights into termite ecology and interactions among consumers of vastly different body sizes across spatial scales.

Soil seed bank dynamics under the influence of grazing as alternative explanation for herbaceous vegetation transitions in semi-arid rangelands

2016 ◽  
Vol 337 ◽  
pp. 253-261 ◽  
Author(s):  
Frank van Langevelde ◽  
Zewdu K. Tessema ◽  
Willem F. de Boer ◽  
Herbert H.T. Prins
Keyword(s):  
Seed Bank ◽  
Alternative Explanation ◽  
Soil Seed Bank ◽  
Herbaceous Vegetation ◽  
Seed Bank Dynamics ◽  
Arid Rangelands ◽  
Semi Arid

scholarly journals Palaeoenvironmental reconstruction based on the Early Holocene Haelen sequence, near Roermond (southeastern Netherlands)

2016 ◽  
Vol 96 (2) ◽  
pp. 115-130 ◽  
Author(s):  
Johanna A.A. Bos ◽  
Bas van Geel
Keyword(s):  
Open Water ◽  
Early Holocene ◽  
Oxbow Lake ◽  
High Temporal Resolution ◽  
Oxbow Lakes ◽  
Humid Climate ◽  
Herbaceous Vegetation ◽  
Large Herbivores ◽  
River Floodplains ◽  
Meuse River

AbstractHigh-resolution Early Holocene palynological records from the middle Meuse River valley were missing until recently. In order to investigate environmental and inferred climate changes during the Preboreal, sediments from a former residual channel of the Meuse River near Haelen were studied. Detailed multi-proxy analyses, including microfossils, macroremains and loss-on-ignition measurements, were carried out at a high temporal resolution. An accurate chronology of the >1000-year-long record was provided by accelerator mass spectrometry (AMS)14C wiggle-match dating.The channel was abandoned during the late Younger Dryas, when accumulation started with gyttja. This period was characterised by an open landscape with herbaceous vegetation and dwarf shrubs. Patches of birch were present on the floodplains around depressions and (oxbow) lakes. Some pines survived the cold in sheltered locations. In the residual channel the water was flowing temporarily and aquatic plant communities developed with predominantly submerged taxa and algae. The shores were fringed by willows and sedges and were probably used as a watering place by large herbivores.Following the Late-glacial/Holocene climate warming, dated in the Haelen record around 11,520 cal BP, birch woodlands expanded on the river floodplains and slopes of terraces during the Friesland Phase. Open vegetation with herbs and juniper remained present on the nearby terraces. An increase in the water level of the oxbow lake and seepage of groundwater occurred. Along the shores herbaceous vegetation was present. Around 11,420 cal BP, birch expansion was interrupted by the dry continental Rammelbeek Phase. On the river floodplain and terrace slopes, open grassland vegetation developed and on the terraces, grasslands and open grounds were abundant. In the residual channel the water became stagnant and floating-leaved vegetation developed. At the start of the Late Preboreal, around 11,270 cal BP, a sudden shift to a more humid climate took place and birch forests expanded again on the river floodplains and terrace slopes. Poplar became more abundant in these forests, and birch and poplar swamp forests were present near the site. Pine expanded atc. 11,160 cal BP on the higher sandy and gravelly terraces. During the Late Preboreal a reed swamp developed on the shores of the residual channel.At the onset of the Boreal, around 10,710 cal BP, woodlands, initially with hazel, but later also with oak, elm and lime, started to develop, while pine forest remained present on the higher terraces. Hazel shrubs were growing on the terrace slopes. Birch and poplar forests occurred on moist parts of the floodplains. Around the residual channel they formed a zone behind the reed swamps surrounding the oxbow lake. Vegetation with water lilies was present in open water.The Haelen record shows, despite a lack of archaeological evidence, indications for the presence of Mesolithic people in the area during the Preboreal. These include the occurrence of (natural or man-made) fires, in combination with the presence of trampled areas and disturbed grounds and possibly consumption of Nymphaeaceae seeds and tubers.

Effects of grazing by large herbivores on plant diversity and productivity of semi-arid alpine steppe on the Qinghai-Tibetan Plateau

2015 ◽  
Vol 37 (4) ◽  
pp. 389 ◽  
Author(s):  
Hasbagan Ganjurjav ◽  
Min-jie Duan ◽  
Yun-fan Wan ◽  
Wei-na Zhang ◽  
Qing-zhu Gao ◽  
...  
Keyword(s):  
Species Diversity ◽  
Tibetan Plateau ◽  
Plant Community ◽  
Plant Diversity ◽  
Net Primary Productivity ◽  
Strong Impact ◽  
Aboveground Net Primary Productivity ◽  
Large Herbivores ◽  
Alpine Steppe ◽  
Semi Arid

Grazing by large herbivores may have a strong impact on plant diversity and productivity, but the effects are expected to vary with grazing pressure. The changes in productivity and species diversity of Stipa purpurea-dominated semi-arid alpine steppe grassland were measured under four different stocking rates of Tibetan sheep [no grazing, light (2.4 sheep units ha–1), moderate (3.6 sheep units ha–1), and heavy (6.0 sheep units ha–1) grazing] in a 5-year (2006–2010) grazing experiment on the Qinghai-Tibetan Plateau, China. Herbage mass and aboveground net primary productivity of alpine steppe declined significantly with increasing stocking rate (P < 0.05). Over the 5 years of the experiment, the proportion of forbs and sedges increased significantly under light and moderate grazing; the proportion of grasses decreased significantly, whereas the proportion of S. purpurea did not change compared with the no grazing treatment. Species diversity was highest under moderate grazing and was significantly higher than the no grazing treatment in 2 years (2008 and 2010). Moderate grazing enhanced the species diversity of the plant community due to an increase in the proportion of forbs. There were significant positive linear correlations between herbage mass and species diversity under no and light grazing. Species diversity was not related to productivity under moderate and heavy grazing. In conclusion, grazing by sheep reduced plant productivity; plant diversity increased under low and moderate grazing, and was as a result of changes in the composition of the plant community of a semi-arid alpine steppe.

Contour bench terrace (shich/shikim) forestry systems in the semi-arid Israeli Negev: Effects on soil quality, geodiversity, and herbaceous vegetation

Geomorphology ◽  
2015 ◽  
Vol 231 ◽  
pp. 376-382 ◽  
Author(s):  
I. Stavi ◽  
E. Fizik ◽  
E. Argaman
Keyword(s):  
Soil Quality ◽  
Herbaceous Vegetation ◽  
Semi Arid

scholarly journals Effect of tree canopy on species composition, diversity and biomass of herbaceous vegetation and soil characteristics in semi-arid forests of the Aravalli hills

2020 ◽  
Author(s):  
Shriya Garg ◽  
Rajendra Kr. Joshi ◽  
Satish Chandra Garkoti
Keyword(s):  
Species Composition ◽  
Physicochemical Properties ◽  
Chemical Properties ◽  
Canopy Gaps ◽  
Herbaceous Species ◽  
Soil Physicochemical Properties ◽  
Herbaceous Vegetation ◽  
Positive Effects ◽  
Physico Chemical ◽  
Semi Arid

Abstract Background: Herbaceous vegetation is of great ecological importance and responds quickly to environmental changes. Present study was aimed to understand the variation in herbaceous species composition, diversity, biomass and soil physicochemical properties in canopy gaps and under the canopy of semi-arid forests in the Aravalli hills. Methods: Four permanent plots consisting of canopy gaps and under canopy were established. To study herbs phytosociological attributes and biomass, 10 quadrats of 0.5 x 0.5 m size were laid in each plot. For soil physico-chemical properties, 5 soil samples were collected randomly at 0-10 cm depth from each plot. Relationship between biodiversity indices, herbs biomass and soil physicochemical properties was determined using Redundancy Analysis (RDA) and correlation analyses. Results: The sites differed in terms of herbaceous species composition, diversity, biomass and soil physico-chemical properties. Canopy gaps were dominated by grasses while forbs were higher under the canopy. Across the sites, poaceae was the dominant family. All species showed contagious distribution pattern. Oplismenus burmannii reported highest IVI (138.0; 230.5) under the canopy while Achyranthes aspera (56.15) and Eragrostis ciliaris (53.1) had highest IVI in canopy gaps. Diversity indices were higher in canopy gaps. Herbaceous community biomass in canopy gaps ranged from 700-900 gm-2 while under the canopy it ranged from 30-70 gm-2. Cenchrus ciliaris (597.97 gm-2) and Chrysopogon sp. (391.2 gm-2) constituted major proportion of biomass in canopy gaps. The soil of under canopy regions had lower pH and bulk density, but higher soil moisture (%), electrical conductivity, soil organic carbon (SOC), soil total nitrogen (TN), SOC stock and soil TN stock than the canopy gaps. Linear positive relationship between species diversity and biomass; negative relationship between soil chemical properties and herbaceous biomass was found in study area. Even though canopy had positive effects on soil physico-chemical properties, overall negative effect on herbaceous diversity and biomass was seen. Conclusions: Reduced light for photosynthesis and tree root competition for soil resources may be the major factors negatively affecting herbaceous diversity and biomass. Canopy had a significant impact and herbs species composition, diversity, biomass and soil physico-chemical properties showed distinct differences in relation to it.

Herbaceous vegetation response to grazing exclusion in patches and inter-patches in semi-arid pasture and woody encroachment

2013 ◽  
Vol 179 ◽  
pp. 125-132 ◽  
Author(s):  
M.K. Good ◽  
N.L. Schultz ◽  
M. Tighe ◽  
N. Reid ◽  
S.V. Briggs
Keyword(s):  
Woody Encroachment ◽  
Vegetation Response ◽  
Herbaceous Vegetation ◽  
Grazing Exclusion ◽  
Semi Arid
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