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21.
Carlos Ovalle Alejandro Del Pozo Miguel A. Casado Belén Acosta José M. de Miguel 《Landscape Ecology》2006,21(4):585-594
The current land use system in the anthropogenic savannas (Espinales) of the Mediterranean climate region of Chile, has resulted in considerable heterogeneity at the landscape level which is
associated with different covers of the legume tree, Acacia caven. The effects of landscape heterogeneity on the diversity and productivity of herbaceous plant communities were studied in
29 plots of 1000 m2, with a wide range of woody cover. A detrended correspondence analysis of the species × plots matrix explained 73% of the
total variation and revealed the existence of two trends of variation in floristic composition: one associated with physiographic
position (hillsides and flatlands) and the other related to the number of years since the last cutting, or coppicing, of A. caven. Despite the great majority of the original herbaceous species having disappeared as a result of the prevailing land use
system, some native species have been able to survive especially on hillside areas with low grazing intensity. Woody cover
was a good indicator of spatial heterogeneity and land use history. It was also correlated with stocking rate, above-ground
biomass of herbaceous vegetation, and soil fertility (organic matter, nitrogen and phosphorus concentration), both on hillsides
and flatlands. The relationship between woody cover and herbaceous plant species richness was significant and unimodal in
flat land areas, and linear, and marginally significant, on hillsides. The consequences of land use changes on the conservation
of the ecological and productive values of grasslands are analyzed. 相似文献
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Samara N. C. Vicentini Priscila S. Casado Giselle de Carvalho Silvino I. Moreira Adriano F. Dorigan Tatiane C. Silva Abimael G. Silva Adriano A. P. Custódio Ana Carolina S. Gomes João L. Nunes Maciel Nichola Hawkins Bruce A. McDonald Bart A. Fraaije Paulo C. Ceresini 《Plant pathology》2022,71(2):304-321
Wheat blast is one of the most important and devastating fungal diseases of wheat in South America, South-east Asia, and now in southern Africa. The disease can reduce grain yield by up to 70% and is best controlled using integrated disease management strategies. The difficulty in disease management is compounded by the lack of durable host resistance and the ineffectiveness of fungicide sprays. New succinate dehydrogenase inhibitor (SDHI) fungicides were recently introduced for the management of wheat diseases. Brazilian field populations of the wheat blast pathogen Pyricularia oryzae Triticum lineage (PoTl) sampled from different geographical regions in 2012 and 2018 were shown to be resistant to both QoI (strobilurin) and DMI (azole) fungicides. The main objective of the current study was to determine the SDHI baseline sensitivity in these populations. Moderate levels of SDHI resistance were detected in five out of the six field populations sampled in 2012 and in most of the strains isolated in 2018. No association was found between target site mutations in the sdhB, sdhC, and sdhD genes and the levels of SDHI resistance, indicating that a pre-existing resistance mechanism not associated with target site mutations is probably present in Brazilian wheat blast populations. 相似文献
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