Seasonal abundance of soil-surface arthropods in relation to some meteorological and edaphic variables of the grassland and tree-planted areas in a tropical semi-arid savanna

1990 ◽  
Vol 34 (1) ◽  
pp. 49-59 ◽  
Author(s):  
M. Vikram Reddy ◽  
B. Venkataiah
Keyword(s):  
Soil Surface ◽  
Seasonal Abundance ◽  
Edaphic Variables ◽  
Semi Arid

Soil erosion controlled by biota along a climate gradient in Chile

2020 ◽  
Author(s):  
Nicolás Riveras ◽  
Kristina Witzgall ◽  
Victoria Rodríguez ◽  
Peter Kühn ◽  
Carsten W. Mueller ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Biological Soil Crust ◽  
Environmental Filtering ◽  
Soil Surface ◽  
Climatic Conditions ◽  
Rainfall Simulation ◽  
Soil Erodibility ◽  
Rainfall Gradient ◽  
The Impact ◽  
Semi Arid

<p>Soil erosion is one of the main problems in soil degradation nowadays and is widely distributed in many landscapes worldwide. Particularly water erosion is widespread and determined by rain erosivity, soil erodibility, topographic factors and the management carried out to mitigate this phenomenon. Although this process is mostly known as a consequence of human management such as agriculture or forestry, it is a process that also occurs naturally, being one of the factors that regulate the shape of the landscape.</p><p>One of the main agents that stabilize the soil surface is biota and its activity, either in the form of plants, microorganisms or as an assemblage in the form of a biological soil crust (biocrusts). However, there are limited studies about how and what extent biota drives soil-stabilizing processes. With particular view on the impact of biocrusts on soil erosion, most studies have been carried out in arid and semi-arid regions, so its influence under other climates is largely unknown.</p><p>This study focuses on the influence of biota on soil erosion in a temperature and rainfall gradient, covering four climate zones (arid, semi-arid, mediterranean and humid) with very limited human intervention. Other variables such as the origin of the geological formation, geographical longitude and glacial influence were kept constant for all study sites. The effect of vegetation (biocrusts) and its abundance, microbiology and terrain parameters are investigated using rainfall simulation experiments under controlled conditions and by a physico-chemical evaluation of the soil, surface runoff, percolation and sediment discharge, in order to determine the different environmental filtering effects that the soil develops under different climatic conditions.</p><p>It is expected that as vegetation vigor and cover increase, soil erodibility will decrease. The biocrust is the protagonist of this stabilization in conditions of low pedological development and will become secondary as edaphoclimatic conditions favor the colonization of plants.</p><p>The results of this study will help to achieve a better understanding of the role of biota in soil erosion control and will clarify its influence on soil losses under different climate and slope conditions. Analyses are currently ongoing and first results of our work will be presented at the EGU 2020.</p>

Surface runoff, soil and nutrient losses from farming systems in the Australian semi-arid tropics

1996 ◽  
Vol 36 (8) ◽  
pp. 1003 ◽  
Author(s):  
M Dilshad ◽  
JA Motha ◽  
LJ Peel
Keyword(s):  
Surface Runoff ◽  
Soil Conservation ◽  
Soil Loss ◽  
Soil Surface ◽  
Farming Systems ◽  
Surface Characteristics ◽  
Control Surface ◽  
Arable Soils ◽  
North West ◽  
Semi Arid

Most soils suitable for dryland agriculture in north-west Australia occur in the Daly Basin. These are sesquioxidic soils which include red, yellow and grey earths, and soils related to yellow and red earths. The potential, for these arable soils to be degraded by highly erosive rainfalls, common to the region, is high. Farming practices strongly influence the soil surface characteristics (vegetation cover, roughness, soil strength), which in turn control surface runoff, and sediment detachment and transport. In studies conducted during 1984-89 in the Daly Basin, conventionally tilled catchments, produced 1.5-2 times more runoff and lost 1.5-6 times more soil than their no-tillage counterparts (all catchments were within soil conservation banks). In these conventionally tilled catchments, soil loss was <8.1 t/ha.year. Other studies in the region have shown that, without soil conservation banks, soil loss can be around 100/ha.year under conventional tillage. Little work, however, has been undertaken on farms in the Australian semi-arid tropics to study the movement of nutrients and herbicides (in ionic and adsorbed forms) and further research is warranted.

scholarly journals Seasonal Abundance and Control of the Rhododendron Gall Midge, Clinodiplosis rhododendri (Felt), in Container Grown Rhododendron catawbiense Michaux

1991 ◽  
Vol 9 (2) ◽  
pp. 68-71
Author(s):  
James L. Hanula
Keyword(s):  
Emerging Adults ◽  
Gall Midge ◽  
Growth Period ◽  
Adult Emergence ◽  
Soil Surface ◽  
Early Growth ◽  
Seasonal Abundance ◽  
Bud Break ◽  
Affect Control ◽  
And Control

Abstract The seasonal abundance and control of the rhododendron gall midge, Clinodiplosis rhododendri (Felt), were investigated on container grown Rhododendron catawbiense Michaux. Most of the midge population studied completed 3 generations, and at least some completed 4–5 generations during the growing season (May–October 1989). Adults that developed from overwintered larvae began emerging on May 14, 1989. Three of the peaks in adult emergence coincided with bud break during the three growth flushes observed in the nursery. Only 20% of the buds were infested during the first growth flush, while 95% were infested during the second and third growth flushes. The low level of infestation during the early growth period provides an opportunity to detect an infestation before extensive damage occurs. Five insecticides were tested as soil drenches to control overwintering larvae. All five were equally effective and reduced the number of emerging adults by 95–100%. Further tests with Dursban 2E (chlorpyrifos) showed that soil surface applications were also effective, and that the timing of irrigation did not affect control. Soil drenches with two additional materials, Safer's insecticidal soap and Pratt horticultural oil, were not effective.

scholarly journals The impact of soil uptake on the global distribution of molecular hydrogen: chemical transport model simulation

2011 ◽  
Vol 11 (2) ◽  
pp. 4059-4103 ◽  
Author(s):  
H. Yashiro ◽  
K. Sudo ◽  
S. Yonemura ◽  
M. Takigawa
Keyword(s):  
Biological Activity ◽  
Seasonal Variation ◽  
Biomass Burning ◽  
Arid Region ◽  
Molecular Hydrogen ◽  
Deposition Velocity ◽  
Soil Surface ◽  
Soil Uptake ◽  
Semi Arid Region ◽  
Semi Arid

Abstract. The molecular hydrogen (H2) in the troposphere is highly influenced by the strength of H2 uptake by the terrestrial soil surface. The global distribution of H2 and its uptake by the soil are simulated by using a model called CHemical AGCM for Study of Environment and Radiative forcing (CHASER), which incorporates a 2-layered soil diffusion/uptake process component. The simulated distribution of deposition velocity over land reflects regional climate and has a global average of 3.3 × 10−2 cm s−1. In the region north of 30° N, the amount of soil uptake increases, particularly in the summer. However, the increase in the uptake becomes smaller in the winter season due to snow cover and a reduction in the biological activity at low temperatures. In the temperate and humid regions in the mid- and low-latitudes, the uptake is mostly influenced by the soil air ratio, which controls the gas diffusivity in the soil. In the semi-arid region, water stress and high temperature contribute to the reduction of biological activity, as well as to the seasonal variation in the deposition velocity. The comparison with the observations shows that the model reproduces both the distribution and seasonal variation of H2 relatively well. The global burden and tropospheric lifetime are 150 Tg and 2.0 yr, respectively. The seasonal variation of H2 in the northern high latitude is mainly controlled by the large seasonal change in soil uptake. In the Southern Hemisphere, the seasonal change in the net chemical production and inter-hemispheric transport are the dominant cause of the seasonal cycle. Large biomass burning impacts the magnitude of seasonal variation mainly in the tropics and subtropics. Both observation and model show large inter-annual variation, especially for the period 1997–1998, associated with the large biomass burning in tropics and northern high-latitudes. The soil uptake shows relatively small inter-annual variability compared to the signal from biomass burning. We note that the thickness of biologically inactive layer near the soil surface and the uptake flux in semi-arid region is important for the current and future budget of atmospheric H2.

Role of irrigation and wastewater reuse: comparison of subsurface irrigation and furrow irrigation

2004 ◽  
Vol 50 (2) ◽  
pp. 61-68 ◽  
Author(s):  
C. Choi ◽  
I. Song ◽  
S. Stine ◽  
J. Pimentel ◽  
C. Gerba
Keyword(s):  
Drip Irrigation ◽  
Arid Regions ◽  
Irrigation System ◽  
Soil Surface ◽  
Furrow Irrigation ◽  
Subsurface Drip Irrigation ◽  
Vegetable Crops ◽  
Viral Contamination ◽  
Subsurface Drip ◽  
Semi Arid

Two different irrigation systems, subsurface drip irrigation and furrow irrigation, are tested to investigate the level of viral contamination and survival when tertiary effluent is used in arid and semi-arid regions. The effluent was injected with bacteriophages of PRD1 and MS2. A greater number of PRD1 and MS2 were recovered from the lettuce in the subsurface drip-irrigated plots as compared to those in the furrow-irrigated plots. Shallow drip tape installation and preferential water paths through cracks on the soil surface appeared to be the main causes of high viral contamination in subsurface drip irrigation plots, which led to the direct contact of the lettuce stems with the irrigation water which penetrated the soil surface. The water use efficiency of the subsurface drip irrigation system was higher than that of the furrow irrigation system. Thus, subsurface drip irrigation is an efficient irrigation method for vegetable crops in arid and semi-arid regions if viral contamination can be reduced. Deeper installation of drip tapes, frequent irrigations, and timely harvests based on cumulative heat units may further reduce health risks by ensuring viral die-off under various field conditions.

Reliability of the Artemisia/Chenopodiaceae pollen ratio in differentiating vegetation and reflecting moisture in arid and semi-arid China

The Holocene ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 858-864 ◽  
Author(s):  
Yuan Wang ◽  
Wei Wang ◽  
Lina Liu ◽  
Yajuan Jiang ◽  
Zhimei Niu ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Surface Sediments ◽  
Qaidam Basin ◽  
Source Area ◽  
Soil Surface ◽  
Mean Annual Precipitation ◽  
Climate Reconstructions ◽  
Moisture Conditions ◽  
Semi Arid ◽  
Inner Mongolia Plateau

The reliability of the ratio between Artemisia and Chenopodiaceae pollen percentage (i.e. A/ C) in differentiating vegetation and reflecting moisture conditions in arid and semi-arid regions has been disputed and this hindered its potential application in palaeoclimate reconstructions. In this paper, we investigated the A/ C ratios of lake-centre surface sediment from 45 lakes in the Inner Mongolia Plateau and the Qaidam Basin in arid and semi-arid China, and numerically studied the relationships of A/ C ratios with vegetation and moisture. We found that the A/ C ratio of lake-centre surface sediments can be used as an effective index to differentiate desert and steppe and also can be used as a valid indicator to infer mean annual precipitation (MAP) in the Inner Mongolia Plateau and the Qaidam Basin in arid and semi-arid China. Moreover, the A/ C ratio from lake-centre surface sediments is more reliable and robust than that of soil-surface samples in differentiating vegetation and reflecting moisture conditions, and this might be attributed to its larger pollen source area and regional representation. In addition, the ( A − C)/( A + C) index helps to overcome the inherent weakness of non-linearity of the A/ C ratio and may be useful in paleo-vegetation reconstruction. These findings provide useful references for pollen-based vegetation and climate reconstructions of lake cores in arid and semi-arid China.

The Influence of Recent Grazing Pressure and Landscape Position on Grass Recruitment in a Semi-Arid Woodland of Eastern Australia.

1996 ◽  
Vol 18 (1) ◽  
pp. 3 ◽  
Author(s):  
VJ Anderson ◽  
KC Hodgkinson ◽  
AC Grice
Keyword(s):  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Run Off ◽  
Eastern Australia ◽  
Annual Grasses ◽  
History Of ◽  
Semi Arid

This study examined the effects of previous grazing pressure, position in the landscape and apparent seed trapping capability of soil surface micro-sites on recruitment of the perennial grass Monachather paradoxa (mulga oats) in a semi-arid woodland. Seedling emergence was counted on small plots which had been kept moist for one month. The plots were on bare ground, or at grass tussocks, or at log mounds, sited in the run-off, interception and run-on zones of paddocks that had been grazed for six years at 0.3 and 0.8 sheep equivalent/ha. Few naturally occurring perennial grass seedlings emerged on any of the sites. The level of previous grazing pressure influenced the recruitment of grasses from natural sources as well as from seed of M. paradoxa broadcast on the soil surface; significantly more grass seedlings recruited in paddocks stocked at 0.3 than at 0.8 sheep/ha. Emergence of the sown grass did not differ significantly between the three zones in the landscape, but trends in the data suggest the interception zone may have been the most favourable. Recruitment from in situ grass seed was highest in the mulga grove (run-on) zone. Most seedlings of the sown grass emerged around the bases of existing perennial grass tussocks, but recruitment of volunteer perennial and annual grasses was more evenly distributed between the mulga log-mounds and perennial grass tussocks. It is concluded that very low levels of readily germinable seed of perennial grasses remained in the soil at the end of the drought and that areas with a history of high grazing pressure have less probability of grass recruitment when suitable rain occurs.

Effect of temporal rainfall distribution and soil type on soil moisture and runoff generation in semi-arid Zimbabwe

2007 ◽  
Vol 38 (3) ◽  
pp. 249-263 ◽  
Author(s):  
F.T. Mugabe ◽  
M.G. Hodnett ◽  
A. Senzanje
Keyword(s):  
Soil Moisture ◽  
Overland Flow ◽  
Daily Rainfall ◽  
Soil Surface ◽  
Runoff Generation ◽  
Stream Channels ◽  
Wet Season ◽  
Sodic Soils ◽  
Rainfall Distribution ◽  
Semi Arid

This paper examines the effect of temporal rainfall distribution on soil moisture and runoff generation in the 5.9 km2 Mutangi catchment in semi-arid Zimbabwe. Rainfall, soil moisture and runoff were measured during the 1999/00 and 2000/01 rainy seasons during which periods 755 mm and 615 mm of rainfall were received, respectively. The percentage of rainfall totals in these periods were 58% and 69%, respectively, in February. The total catchment runoff was 102 mm and 63 mm, of which 52% and 49% were recorded over 6 and 4 d in 2000 and 2001, respectively. Baseflow was negligible. Rainfall intensities were generally low. In the 1999/00 season there were 2 and 8 h with intensities &gt;20 mm h−1 and 10 mm h−1, respectively. Some runoff appears to be generated by Hortonian overland flow (HOF), mainly in the early wet season before ploughing creates a rougher soil surface. The dominant process of runoff in this catchment was saturated overland flow (SOF), which occurs when the soils become saturated from below. The sodic soils along the stream channels appear to generate most of the runoff because of their small capacity to store water before saturation. The ridge soils are coarse sands, with a large capacity to store rainfall. The transitional (slope) soils have an intermediate capacity to store water. If there is a sequence of daily events that completely fills the storage available in both the sodic and transitional soils, and which begins to saturate the ridge soils, there could be very large amounts of runoff (&gt;50% of the daily rainfall). The occurrence of such runoff events depends very heavily on the distribution of rainfall. Dry spells between rain events create storage, thereby reducing the risk of runoff from the next events.

Small-scale spatial patterns of two soil lichens in semi-arid Mediterranean steppe

2003 ◽  
Vol 35 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Fernando T. Maestre
Keyword(s):  
Spatial Distribution ◽  
Correlation Analysis ◽  
Spatial Pattern ◽  
Soil Surface ◽  
Arid Ecosystems ◽  
Small Scale ◽  
Significant Relationships ◽  
Arid Steppe ◽  
The Individual ◽  
Semi Arid

AbstractBiological crusts are a common feature of the soil surface in arid and semi-arid ecosystems, where they play a major role in ecosystem functioning. In recent years, there has been an increasing interest in the ecophysiology, floristics, and dynamics of crust-forming lichens but little is known about the effect of vascular plants on their small-scale spatial distribution. To increase our understanding about the interactions between crust-forming lichens and vegetation in semi-arid areas, the spatial pattern and interaction of two soil lichens, Cladonia convoluta and Squamarina cartilaginea, at two microsites in semi-arid Stipa tenacissima steppe of south-eastern Spain are evaluated. The aim of this study was to determine if the microsite provided by Stipa tussocks promoted changes in the individual patterns and in the spatial covariation of these soil lichens. Spatial analysis by distance index (SADIE) coupled with correlation analysis was used to explore the individual patterns and the spatial relationships between the two species. SADIE detected a significant clumped pattern in the spatial distribution of both species, but Stipa tussocks promoted changes only in the spatial pattern of Cladonia. Correlation analysis revealed the presence of significant relationships between the two species, particularly close to Stipa tussocks. The results show that the microenvironment provided by Stipa is able to modify the small-scale spatial pattern of soil lichens in semi-arid steppe, and suggest the presence of facilitation between Stipa and Cladonia.

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