The impact of chestnut blight, caused by the fungal pathogen Cryphonectria parasitica, has diminished in Europe due to a natural biological control caused by hypovirus infection. Hypovirulence-mediated biological cont...The impact of chestnut blight, caused by the fungal pathogen Cryphonectria parasitica, has diminished in Europe due to a natural biological control caused by hypovirus infection. Hypovirulence-mediated biological control has been far less successful in North America meriting further evaluation of field isolates that have the ability to produce non-lethal cankers, generate hypovirulent inoculum, and exhibit a greater ecological fitness in forest systems. In this study, Cryphonectria hypoviruses (CHV) CHV3-County Line, CHV1-Euro7, and CHV1-Ep713 were evaluated in five different isolates of C. parasitica. One hundred and eighty cankers representing each treatment combination were initiated on American chestnut sprouts in the Monongahela National Forest, West Virginia, USA. The size of cankers, the persistence of hypovirulent (HV) isolates, stroma production, and hypovirus transmission to conidia were assessed four and 12 months after canker expansion. CHV3-County Line infected isolates produced significantly smaller cankers than the isolates infected with either CHV1-type. With regard to CHV1-Euro7 isolates, the fungal genome appeared to contribute to the differences in canker size. After four months, HV isolates harboring either CHV1-type (30%) were retrieved at a significantly higher rate than isolates containing CHV3-County Line (14%). After 12 months, the HV recovery was similar among the three hypoviruses indicating smaller cankers will maintain their HV status after one year. Very few stroma were produced after one year in the field from HV isolates. In vitro, CHV3-County Line (49%) had a significantly lower rate of hypovirus transmission to conidia when compared to CHV1-Euro7 (87%) and CHV1-Ep713 (80%). Significant differences existed among the five different isolates indicating HV transmission is dependent on the fungal genome. This research provided additional evidence that each hypovirus interacts with its host differently and certain isolate/hypovirus combinations have better biological control potential than others.展开更多
Vegetation and soil within estuarine ecosystems play an integral role in ecological processes within pocket estuaries. However, physical barriers, caused by culverts diminish hydrological inputs, sediment exchange, an...Vegetation and soil within estuarine ecosystems play an integral role in ecological processes within pocket estuaries. However, physical barriers, caused by culverts diminish hydrological inputs, sediment exchange, and habitat connectivity. The restoration of estuaries by bridge replacement reconnects <span>the aquatic corridor, however, the recovery of plant communities and soil s</span>ubstrate is not well understood. This observational study monitored four estuary restoration sites of variable ages (0 - 12 years) in Western Washington, USA. Plant community composition, soil organic carbon, organic matter, and soil nutrients were assessed. Percent soil carbon was different among the pre-restoration and youngest (3-year) post-restoration site (<i>P</i> = 0.03), suggesting an initial decrease in carbon and organic matter during restoration. Both N and P were deficient at the newest, lower restoration site, presumably linked to the lack of organic matter required for adequate cation exchange capacity and nutrient/plant exchange (<i>P</i> < 0.05). Plant species diversity was higher at the intermediate (9-year) and oldest post-restoration sites (12-year;<i>P</i> = 0.02). Vegetation composition was primarily native species with few invasive plants present. The results of this study illustrate that tidal marsh plant communities are influenced by the development of salinity and vertical gradients with older sites having an increase in species diversity. Future surveys are ongoing to <span>better understand how these sites recover organic matter and tidal marsh co</span>mmunities to form adequate estuarine habitat over time.展开更多
Empirical Orthogonal Function (EOF) analysis and the related Principal Components (PC) analysis are used to extract valuable vegetation cover derived information from the National Oceanic and Atmos- pheric Administrat...Empirical Orthogonal Function (EOF) analysis and the related Principal Components (PC) analysis are used to extract valuable vegetation cover derived information from the National Oceanic and Atmos- pheric Administration (NOAA-AVHRR)'s Leaf Area Index (LAI) satellite images. Results suggest that from 1982 to 2000 global climate change has contributed to an increase in vegetation cover in the Qinghai-Tibet Plateau. The correlation between rainfall and LAI EOF PC1 and PC2 indicates that rainfall is the major climatic factor influencing interannual variations of average vegetation cover throughout the entire Plateau. However, annual mean vegetation cover trends in the Qinghai-Tibet Plateau are mainly out of phase with air temperature increasing, which is primarily responsible for nonsynchro- nous changes of vegetation cover. In the southern ridge of the Qinghai-Tibet Plateau, recent warming trends contribute to humid weather and favorable conditions for vegetation growth. By contrast, higher temperatures have led to arid conditions and insufficient rainfall in the northern part of the Plateau, leading to drought and other climatic conditions which are not conducive to increased vegetation cover.展开更多
基金jointly supported by the Key Project of Chinese Academy of Sciences(Grant No.KZCX3-SW-221)the National Natural Science Foundation of China(Grant Nos.40675047 and 40233027).
文摘The impact of chestnut blight, caused by the fungal pathogen Cryphonectria parasitica, has diminished in Europe due to a natural biological control caused by hypovirus infection. Hypovirulence-mediated biological control has been far less successful in North America meriting further evaluation of field isolates that have the ability to produce non-lethal cankers, generate hypovirulent inoculum, and exhibit a greater ecological fitness in forest systems. In this study, Cryphonectria hypoviruses (CHV) CHV3-County Line, CHV1-Euro7, and CHV1-Ep713 were evaluated in five different isolates of C. parasitica. One hundred and eighty cankers representing each treatment combination were initiated on American chestnut sprouts in the Monongahela National Forest, West Virginia, USA. The size of cankers, the persistence of hypovirulent (HV) isolates, stroma production, and hypovirus transmission to conidia were assessed four and 12 months after canker expansion. CHV3-County Line infected isolates produced significantly smaller cankers than the isolates infected with either CHV1-type. With regard to CHV1-Euro7 isolates, the fungal genome appeared to contribute to the differences in canker size. After four months, HV isolates harboring either CHV1-type (30%) were retrieved at a significantly higher rate than isolates containing CHV3-County Line (14%). After 12 months, the HV recovery was similar among the three hypoviruses indicating smaller cankers will maintain their HV status after one year. Very few stroma were produced after one year in the field from HV isolates. In vitro, CHV3-County Line (49%) had a significantly lower rate of hypovirus transmission to conidia when compared to CHV1-Euro7 (87%) and CHV1-Ep713 (80%). Significant differences existed among the five different isolates indicating HV transmission is dependent on the fungal genome. This research provided additional evidence that each hypovirus interacts with its host differently and certain isolate/hypovirus combinations have better biological control potential than others.
文摘Vegetation and soil within estuarine ecosystems play an integral role in ecological processes within pocket estuaries. However, physical barriers, caused by culverts diminish hydrological inputs, sediment exchange, and habitat connectivity. The restoration of estuaries by bridge replacement reconnects <span>the aquatic corridor, however, the recovery of plant communities and soil s</span>ubstrate is not well understood. This observational study monitored four estuary restoration sites of variable ages (0 - 12 years) in Western Washington, USA. Plant community composition, soil organic carbon, organic matter, and soil nutrients were assessed. Percent soil carbon was different among the pre-restoration and youngest (3-year) post-restoration site (<i>P</i> = 0.03), suggesting an initial decrease in carbon and organic matter during restoration. Both N and P were deficient at the newest, lower restoration site, presumably linked to the lack of organic matter required for adequate cation exchange capacity and nutrient/plant exchange (<i>P</i> < 0.05). Plant species diversity was higher at the intermediate (9-year) and oldest post-restoration sites (12-year;<i>P</i> = 0.02). Vegetation composition was primarily native species with few invasive plants present. The results of this study illustrate that tidal marsh plant communities are influenced by the development of salinity and vertical gradients with older sites having an increase in species diversity. Future surveys are ongoing to <span>better understand how these sites recover organic matter and tidal marsh co</span>mmunities to form adequate estuarine habitat over time.
基金the National Basic Research Program of China (Grant No. 2006CB403607)the National Natural Science Foundation of China (Grant Nos. 40675047 and 40605023)+1 种基金the Key Project of the Chinese Academy of Sciences (Grant No. KZCX2-YW-219)a Western Washington University summer research grant
文摘Empirical Orthogonal Function (EOF) analysis and the related Principal Components (PC) analysis are used to extract valuable vegetation cover derived information from the National Oceanic and Atmos- pheric Administration (NOAA-AVHRR)'s Leaf Area Index (LAI) satellite images. Results suggest that from 1982 to 2000 global climate change has contributed to an increase in vegetation cover in the Qinghai-Tibet Plateau. The correlation between rainfall and LAI EOF PC1 and PC2 indicates that rainfall is the major climatic factor influencing interannual variations of average vegetation cover throughout the entire Plateau. However, annual mean vegetation cover trends in the Qinghai-Tibet Plateau are mainly out of phase with air temperature increasing, which is primarily responsible for nonsynchro- nous changes of vegetation cover. In the southern ridge of the Qinghai-Tibet Plateau, recent warming trends contribute to humid weather and favorable conditions for vegetation growth. By contrast, higher temperatures have led to arid conditions and insufficient rainfall in the northern part of the Plateau, leading to drought and other climatic conditions which are not conducive to increased vegetation cover.
基金国家重点基础研究发展计划(批准号:2006CB403607)国家自然科学基金(批准号:40675047,40605023)+1 种基金中国科学院创新项目(批准号:KZCX2-YW-219)A Western Washington University Summer Research Grant联合资助
