Spatial heterogeneity of subsurface soil texture drives landscape-scale patterns of woody patches in a subtropical savanna

2017 ◽  
Vol 32 (4) ◽  
pp. 915-929 ◽  
Author(s):  
Yong Zhou ◽  
Thomas W. Boutton ◽  
X. Ben Wu ◽  
Chenghai Yang
2010 ◽  
Vol 100 (11) ◽  
pp. 1146-1161 ◽  
Author(s):  
Peter Skelsey ◽  
Walter A. H. Rossing ◽  
Geert J. T. Kessel ◽  
Wopke van der Werf

Strategic spatial patterning of crop species and cultivars could make agricultural landscapes less vulnerable to plant disease epidemics, but experimentation to explore effective disease-suppressive landscape designs is problematic. Here, we present a realistic, multiscale, spatiotemporal, integrodifference equation model of potato late blight epidemics to determine the relationship between spatial heterogeneity and disease spread, and determine the effectiveness of mixing resistant and susceptible cultivars at different spatial scales under the influence of weather. The model framework comprised a landscape generator, a potato late blight model that includes host and pathogen life cycles and fungicide management at the field scale, and an atmospheric dispersion model that calculates spore dispersal at the landscape scale. Landscapes consisted of one or two distinct potato-growing regions (6.4-by-6.4-km) embedded within a nonhost matrix. The characteristics of fields and growing regions and the separation distance between two growing regions were investigated for their effects on disease incidence, measured as the proportion of fields with ≥1% severity, after inoculation of a single potato grid cell with a low initial level of disease. The most effective spatial strategies for suppressing disease spread in a region were those that reduced the acreage of potato or increased the proportion of a resistant potato cultivar. Clustering potato cultivation in some parts of a region, either by planting in large fields or clustering small fields, enhanced the spread within such a cluster while it delayed spread from one cluster to another; however, the net effect of clustering was an increase in disease at the landscape scale. The planting of mixtures of a resistant and susceptible cultivar was a consistently effective option for creating potato-growing regions that suppressed disease spread. It was more effective to mix susceptible and resistant cultivars within fields than plant some fields entirely with a susceptible cultivar and other fields with a resistant cultivar, at the same ratio of susceptible to resistant potato plants at the landscape level. Separation distances of at least 16 km were needed to completely prevent epidemic spread from one potato-growing region to another. Effects of spatial placement of resistant and susceptible potato cultivars depended strongly on meteorological conditions, indicating that landscape connectivity for the spread of plant disease depends on the particular coincidence between direction of spread, location of fields, distance between the fields, and survival of the spores depending on the weather. Therefore, in the simulation of (airborne) pathogen invasions, it is important to consider the large variability of atmospheric dispersion conditions.


1992 ◽  
Vol 23 (3-4) ◽  
pp. 345-362 ◽  
Author(s):  
D.A. Shannon ◽  
E.A. Kueneman ◽  
M.J. Wright ◽  
C.W. Wood

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Kirsty J. Morris ◽  
Brian J. Bett ◽  
Jennifer M. Durden ◽  
Noelie M. A. Benoist ◽  
Veerle A. I. Huvenne ◽  
...  

Ecosphere ◽  
2016 ◽  
Vol 7 (3) ◽  
Author(s):  
Alexander W. Latzka ◽  
Gretchen J.A. Hansen ◽  
Matthew Kornis ◽  
M. Jake Vander Zanden

Oecologia ◽  
2018 ◽  
Vol 186 (4) ◽  
pp. 1127-1135 ◽  
Author(s):  
Yong Zhou ◽  
Thomas W. Boutton ◽  
X. Ben Wu ◽  
Cynthia L. Wright ◽  
Anais L. Dion

2020 ◽  
Author(s):  
Nikolai Lozbenev ◽  
Daniil Kozlov

<p>The modern Russian agroecological landscape evaluation is based on identification of areas with specific hydrology, soil and terrain constraints to crop, that are named as agroecological groups of lands. Soil quality of the lands is characterized by a combination of conditions ensuring sustainable crop yields and determining the ecological functions and stability of agrolandscapes. The main differences in soil quality in the forest-steppe of the East European Plain are due to soil erosion and precipitation redistribution by the topography elements. If the erosion processes are comprehensively studied by the world scientific community, then the influence of differences in soil moisture reserves, its spatial heterogeneity and potential impact on the crops productivity is not sufficiently considered by Russian specialists. In this regard, large-scale studies were carried out at two key areas: the Central Russian Upland (Kursk region) and the Oka-Don Lowland (Tambov region). The studies included conventional mapping with identification of agroecological groups of lands and their quality assessment using GIS and statistical analysis. To determine the spatial heterogeneity of the moisture conditions, the SIMWE simulation model was applied. This model calculates the precipitation redistribution by the topography elements using digital elevation model and several input parameters. It was find, that the territory of the Central Russian Upland is characterized by normal moisture conditions, leaching water regime, silty-loamy soil texture. Redistribution of precipitation occurs without delay, as a result of which most of the territory does not experience overmoistening and the soils are highly productive with moisture reserves in the top meter layer up to 150 mm. The spatial structure of soil water capacity in a meter soil layer was determined by the regression analysis method of the measured soil moisture and calculated runoff using the SIMWE model. It was determined that the intra-landscape variation of moisture capacity as an indicator of soil quality for agriculture is associated with the topography of the interfluves and the erosion. The second key area, the Oka-Don Lowland, is characterized by a lowland topography and clay soil texture, and excess of moisture in soils in almost all years. Several agroecological groups of lands with significantly different in soil water capacity. To determine the spatial structure of soil water capacity, the SIMWE model was also used, that showed a high intra-landscape soils diversity, that is due to a flat topography of interfluve with lots of depressions. The soils of drained interfluves with a short-term overmoistening and a groundwater level below 6 meters are of the highest quality. In addition, hydromorphic lands with groundwater above 6 meters and average annual moisture reserves in top meter soil layer up to 300 mm are distinguished. They occupy about 72% of the total area of ​​the key site. Such lands are suitable for cultivation of perennial grasses, winter wheat, soybeans, sunflowers and others.</p><p>This study is supported by Russian Foundation for Basic Research, grant №19-29-05277.</p>


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