scholarly journals Performance of Conservation Techniques for Semiarid Environments: Field Observations with Caatinga, Mulch, and Cactus Forage Palma

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 792 ◽  
Author(s):  
Iug Lopes ◽  
Abelardo A. A. Montenegro ◽  
João L. M. P. de Lima
Keyword(s):  
Vegetation Cover ◽  
Soil Conservation ◽  
Bare Soil ◽  
Natural Vegetation ◽  
Soil Reclamation ◽  
Soil Conditions ◽  
Small Scale ◽  
The Impact ◽  
Semi Arid ◽  
Soil Losses

Understanding small-scale hydrologic processes and the impact of soil conservation techniques are crucial in reducing runoff and sediment losses in semi-arid regions. This study was conducted in the Alto Ipanema River Basin, in Pernambuco State (Brazil). Soil and water dynamics were intensely monitored in twelve experimental plots with different coverage conditions (plot with bare soil—Bare; plot with natural vegetation—Natur; plot with mulch—Mulch; plot with Cactus Palma—Palma). By far, bare soil conditions produced higher runoff and soil losses. Mulch cover was close to natural vegetation cover, but still presented higher runoff and sediment losses. Palma, which is a very popular spineless cactus for animal feed in the Brazilian semi-arid region, presented an intermediate hydrologic impact in controlling runoff, enhancing soil moisture, and also reducing soil losses. Experiments were conducted in one hydrologic year (2016/2017) at three different sites. They were intensely monitored and had the same number of plots. This enabled us to carry out a robust performance assessment of the two soil conservation practices adopted (Mulch and Palma), compared to natural vegetation cover and bare soil conditions. Such low-cost alternatives could be easily adopted by local farms in the region, and, hence, improve soil reclamation and regional resiliency in a water-scarce environment.

scholarly journals Green Vegetation Cover Dynamics in a Heterogeneous Grassland: Spectral Unmixing of Landsat Time Series from 1999 to 2014

2020 ◽  
Vol 12 (22) ◽  
pp. 3826 ◽  
Author(s):  
Yuhong He ◽  
Jian Yang ◽  
Xulin Guo
Keyword(s):  
Time Series ◽  
Vegetation Cover ◽  
Driving Forces ◽  
Spectral Unmixing ◽  
Landsat Images ◽  
Green Vegetation ◽  
Arid Grasslands ◽  
Spectral Mixture ◽  
The Impact ◽  
Semi Arid

The ability to quantify green vegetation across space and over time is useful for studying grassland health and function and improving our understanding of the impact of land use and climate change on grasslands. Directly measuring the fraction of green vegetation cover is labor-intensive and thus only practical on relatively smaller experimental sites. Remote sensing vegetation indices, as a commonly-used method for large-area vegetation mapping, were found to produce inconsistent accuracies when mapping green vegetation in semi-arid grasslands, largely due to mixed pixels including both photosynthetic and non-photosynthetic material. The spectral mixture approach has the potential to map the fraction of green vegetation cover in a heterogeneous landscape, thanks to its ability to decompose a spectral signal from a mixed pixel into a set of fractional abundances. In this study, a time series of fractional green vegetation cover (FGVC) from 1999 to 2014 is estimated using the spectral mixture approach for a semi-arid mixed grassland, which represents a typical threatened, species-rich habitat in Central Canada. The shape of pixel clouds in each of the Landsat images is used to identify three major image endmembers (green vegetation, bare soil/litter, and water/shadow) for automated image spectral unmixing. The FGVC derived through the spectral mixture approach correlates highly with field observations (R2 = 0.86). Change in the FGVC over the study period was also mapped, and green vegetation in badlands and uplands is found to experience a slight increase, while vegetation in riparian zone shows a decrease. Only a small portion of the study area is undergoing significant changes, which is likely attributable to climate variability, bison reintroduction, and wildfire. The results of this study suggest that the automated spectral unmixing approach is promising, and the time series of medium-resolution images is capable of identifying changes in green vegetation cover in semi-arid grasslands. Further research should investigate driving forces for areas undergoing significant changes.

The impact of recent land-use change in the Araucaria araucana forest in northern Patagonia

The Holocene ◽  
2020 ◽  
Vol 30 (8) ◽  
pp. 1101-1114 ◽  
Author(s):  
Ricardo Moreno-Gonzalez ◽  
Thomas Giesecke ◽  
Sonia L Fontana
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Vegetation Cover ◽  
Natural Vegetation ◽  
Northern Patagonia ◽  
Rumex Acetosella ◽  
Araucaria Araucana ◽  
The 1950S ◽  
The Impact ◽  
Nothofagus Dombeyi

Land-use change in the form of extensive Pinus plantations is currently altering the natural vegetation cover at the forest–steppe ecotone in northern Patagonia. Providing recommendations for conservation efforts, with respect to this recent and earlier land-use changes, requires a longer time perspective. Using pollen analysis, we investigated to what degree the colonization of the area by Euro-American settlers changed the forest composition and the vegetation cover, and to explore the spread of the European weed Rumex acetosella. This study is based on short sediment cores from six lakes in the Araucaria araucana forest region, across the vegetation gradient from the forest to the steppe. Results document that although Araucaria araucana has been extensively logged elsewhere, near the investigated sites, populations were rather stable and other elements of the vegetation changed little with the initiation of Euro-American settlements. A reduction of Nothofagus dombeyi-type pollen occurred at some sites presumably due to logging Nothofagus dombeyi trees, while toward the steppe, Nothofagus antarctica shrubs may have been removed for pasture. The appearance of Rumex acetosella pollen is consistent with the initiation of land use by Euro-American settlers in all cores, probably indicating the onset of animal farming. The rise of the Rumex acetosella pollen curve during the 1950s marks more recent land-use change. These observations indicate that the spread and local expansion of the weed requires disturbance. Overall, the study shows that the initial colonization of the area by Euro-American settlers had little effect on the natural vegetation structure, while developments since the 1950s are strongly altering the natural vegetation cover.

The Effect of Microsite Variation on Seed-Germination and Seedling Survival of Eucalyptus delegatensis

1993 ◽  
Vol 41 (2) ◽  
pp. 169 ◽  
Author(s):  
M Battaglia ◽  
JB Reid
Keyword(s):  
Seed Germination ◽  
Seedling Survival ◽  
Soil Conditions ◽  
Small Scale ◽  
Root Penetration ◽  
Mean Survival Time ◽  
The Mean ◽  
Developmental Characteristics ◽  
The Impact ◽  
Eucalyptus Delegatensis

The correlation between microsite and seedling numbers was determined in field sowings, and the impact of microsites on germination and seedling survival tested in artificial seedbeds in the glasshouse. Small scale variation in soil conditions, at the scale of tens of centimetres, markedly affected the germination and establishment of Eucalyptus delegatensis R.T.Baker seeds and seedlings. Under conditions of limiting soil moisture, microsites that afforded protection, and probably resulted in increased humidity, caused a marked increase in germination number and rate. The mean survival time was significantly higher on these protected microsites than on less protected microsites, or on microsites that restricted root penetration. The importance of this variability in microtopography was strongly influenced by season and the level of environmental stress, and was diminished as seedlings aged. Due to the different requirements for seed germination and seedling growth, a favourable microsite for germination was not necessarily a favourable site for seedling survival. A comparison of seed and seedling responses to water stress indicated that for E. delegatensis, at least, selection due to microsite differences at the time of germination may not have an impact on the developmental characteristics of the seedlings.

scholarly journals Modelling the impact of small-scale heterogeneities on tree-grass coexistence in semi-arid savannas

1998 ◽  
Vol 86 (5) ◽  
pp. 780-793 ◽  
Author(s):  
F. Jeltsch ◽  
S.J. Milton ◽  
W.R.J. Dean ◽  
N. Rooyen ◽  
K.A. Moloney
Keyword(s):  
Small Scale ◽  
The Impact ◽  
Semi Arid

scholarly journals Quantifying the impact of environmental factors on the spatiotemporal structure of insect communities in a semi-arid Sabkha ecosystem

2015 ◽  
Author(s):  
Haroun Chenchouni ◽  
Taha Menasria ◽  
Souad Neffar ◽  
Smail Chafaa ◽  
Liès Bradai ◽  
...  
Keyword(s):  
Species Richness ◽  
Vegetation Cover ◽  
Shannon Index ◽  
Trophic Groups ◽  
Insect Community ◽  
Insect Communities ◽  
Vegetation Parameters ◽  
Two Parameters ◽  
The Impact ◽  
Semi Arid

The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, where Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different site stations and seasons.

scholarly journals Weed Suppression in Pumpkin by Mulches Composed of Organic Municipal Waste Materials

HortScience ◽  
2016 ◽  
Vol 51 (6) ◽  
pp. 720-726 ◽  
Author(s):  
Caitlin E. Splawski ◽  
Emilie E. Regnier ◽  
S. Kent Harrison ◽  
Mark A. Bennett ◽  
James D. Metzger
Keyword(s):  
Soil Temperature ◽  
Bare Soil ◽  
Weed Suppression ◽  
Control Measures ◽  
Soil Conditions ◽  
Small Scale ◽  
Plastic Mulch ◽  
Weed Biomass ◽  
Squash Bug ◽  
Black Plastic

Field studies were conducted in 2011 and 2012 to compare mulch treatments of shredded newspaper, a combination of shredded newspaper plus turfgrass clippings (NP + grass), hardwood bark chips, black polyethylene plastic, and bare soil on weeds, insects, soil moisture, and soil temperature in pumpkins. Newspaper mulch or black plastic reduced total weed biomass ≥90%, and woodchip or NP + grass mulch each reduced total weed biomass 78% compared with bare soil under high rainfall conditions in 2011. In 2012, under low rainfall, all mulches reduced weed biomass 97% or more compared with bare soil. In both years, all mulches resulted in higher squash bug infestations than bare soil. The woodchip, newspaper, and NP + grass mulches retained higher soil moistures than bare soil or black plastic over the course of each growing season, and the woodchip and NP + grass mulches caused greatest fluctuations in soil temperature. Pumpkin yields were abnormally low in 2011 and did not differ among treatments. In 2012, all mulches produced greater total marketable pumpkin fruit weights compared with bare soil, but only black plastic, newspaper, and NP + grass mulches resulted in greater total numbers of marketable pumpkins. Overall results indicate that shredded newspaper or NP + grass mulches may be useful for organic and/or small-scale urban crop producers as sustainable alternatives to black plastic mulch; however, their weed suppression efficacy may require higher application rates with increasing moisture conditions, and they may require greater squash bug control measures than under bare soil conditions.

Area-wide detection and spatial modeling of signs of bioturbation activity along a climate and elevation gradient in Chile using UAV and their dependence on vegetation and soil characteristics

2020 ◽  
Author(s):  
Paulina Grigusova ◽  
Diana Kraus ◽  
Annegret Larsen ◽  
Alexander Klug ◽  
Robin Fischer ◽  
...  
Keyword(s):  
Land Use ◽  
Surface Roughness ◽  
Vegetation Cover ◽  
Point Cloud ◽  
Elevation Gradient ◽  
Soil Characteristics ◽  
Soil Conditions ◽  
Vegetation Density ◽  
Climate Zones ◽  
Semi Arid

<p>The impact of soil dwelling animals on the terrain shaping is assumed to be largely coupled with vegetation and soil characteristics, particularly in arid and semi-arid regions. The vegetation determines the habitat availability by providing necessary resources such as food and shelter while the burrowing activities of soil dwelling animals impacts at the same time soil properties and nutrient fluxes needed for plant growth. This important relationship and feedbacks between bioturbators, vegetation, climate, soil conditions and landscape shaping is to date completely understudied, particularly the dependencies between soil animals and the vegetation cover. Thus, comprehensive studies to gain a detailed understanding are urgently required. Here, we modeled the presence of all signs of bioturbation (burrows, holes and mounds) within a study area of 1 km<sup>2</sup> with an elevation gradient of 100m height difference in a semi-arid (Santa Gracia, Chile) and Mediterranean (NP La Campana, Chile) zone of coastal Chile using UAV (unmanned aerial vehicle) images. We then compared their relationship between the two climate zones in regard to the vegetation, elevation and soil characteristics. <span>The images were obtained at a flight altitude of 15-60 meters above one study area per each climate zone by means of a Solo quadropter drone equipped with a RGB GoPro camera. Ancillary </span><em><span>in-situ</span></em> <span>data were measured within 10 plots per study area with a size of 10m x 10m. Within the plots, the amount and size of the burrows and mounds as well as the vegetation cover was quantified. In addition, the GPS coordinates of several holes and mounds with a diameter of 10cm and above were measured. Twenty representative soil samples in regard to the land cover, vegetation type and presence of bioturbation activity were taken along the elevation gradient and analyzed for skeleton fraction, soil texture, bulk density and water content. </span>The RGB images obtained by the drone system were firstly used for a supervised land-use classification and to calculate the vegetation density across the study area. The surface roughness was estimated by creating the point cloud of the area and calculating the standard deviation of the point cloud and original images using moving window of 5x5 pixels/points. The presence of soil animal activity was modeled using random forest where drone images, digital elevation model, surface roughness and land cover characteristics (land use, vegetation density and type) were used as predictors. The results showed modeled spatial distribution of burrows and mounds within the study areas, and a dependence of the predicted bioturbation activity on vegetation density and type as well as on elevation and soil conditions along the elevation gradient at both sites. The dependencies are finally compared between the two climate zones.</p>

scholarly journals Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Emmanuel Mavhura ◽  
Desmond Manatsa ◽  
Terence Mushore
Keyword(s):  
Crop Production ◽  
Smallholder Farmers ◽  
Meteorological Data ◽  
Rainfall Variability ◽  
Small Scale ◽  
Arid Environments ◽  
Water Shortages ◽  
The Impact ◽  
Semi Arid ◽  
Zambezi Valley

Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to examine the rainfall variability in the study area and the drought-coping mechanisms employed by smallholder famers respectively. The results show that there are various strategies used by smallholder farmers to cope with the impact of drought. These strategies include drought-tolerant crop production, crop variety diversification, purchasing cereals through asset sales, non-governmental organisations’ food aid and gathering wild fruit. However, consecutive droughts have resulted in high food insecurity and depletion of household assets during droughts. Smallholder farmers in the valley have also resorted to a number of measures taken before, during and after the drought. Still, these strategies are not robust enough to cope with this uncertainty

scholarly journals Modelling Small-Scale Storage Interventions in Semi-Arid India at the Basin Scale

2021 ◽  
Vol 13 (11) ◽  
pp. 6129
Author(s):  
Robyn Horan ◽  
Pawan S. Wable ◽  
Veena Srinivasan ◽  
Helen E. Baron ◽  
Virginie J. D. Keller ◽  
...  
Keyword(s):  
Water Resource Management ◽  
Large Scale ◽  
Data Availability ◽  
Small Scale ◽  
Catchment Scale ◽  
Check Dams ◽  
Basin Scale ◽  
The Impact ◽  
Availability Assessment ◽  
Semi Arid

There has been renewed interest in the performance, functionality, and sustainability of traditional small-scale storage interventions (check dams, farm bunds and tanks) used within semi-arid regions for the improvement of local water security and landscape preservation. The Central Groundwater Board of India is encouraging the construction of such interventions for the alleviation of water scarcity and to improve groundwater recharge. It is important for water resource management to understand the hydrological effect of these interventions at the basin scale. The quantification of small-scale interventions in hydrological modelling is often neglected, especially in large-scale modelling activities, as data availability is low and their hydrological functioning is uncertain. A version of the Global Water Availability Assessment (GWAVA) water resources model was developed to assess the impact of interventions on the water balance of the Cauvery Basin and two smaller sub-catchments. Model results demonstrate that farm bunds appear to have a negligible effect on the average annual simulated streamflow at the outlets of the two sub-catchments and the basin, whereas tanks and check dams have a more significant and time varying effect. The open water surface of the interventions contributed to an increase in evaporation losses across the catchment. The change in simulated groundwater storage with the inclusion of interventions was not as significant as catchment-scale literature and field studies suggest. The model adaption used in this study provides a step-change in the conceptualisation and quantification of the consequences of small-scale storage interventions in large- or basin-scale hydrological models.

scholarly journals Quantifying the impact of environmental factors on the spatiotemporal structure of insect communities in a semi-arid Sabkha ecosystem

2015 ◽  
Author(s):  
Haroun Chenchouni ◽  
Taha Menasria ◽  
Souad Neffar ◽  
Smail Chafaa ◽  
Liès Bradai ◽  
...  
Keyword(s):  
Species Richness ◽  
Vegetation Cover ◽  
Shannon Index ◽  
Trophic Groups ◽  
Insect Community ◽  
Insect Communities ◽  
Vegetation Parameters ◽  
Two Parameters ◽  
The Impact ◽  
Semi Arid

The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, where Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different site stations and seasons.

Sign in / Sign up

Export Citation Format

Share Document