The common fig(Ficus carica L.),Moraceae family,is a commonly grown fruit tree in the Mediterranean region.Fig mosaic disease(FMD)poses a substantial threat to Saudi Arabia’s fig-producing economy.A survey was conduc...The common fig(Ficus carica L.),Moraceae family,is a commonly grown fruit tree in the Mediterranean region.Fig mosaic disease(FMD)poses a substantial threat to Saudi Arabia’s fig-producing economy.A survey was conducted during the two seasons of 2021 and 2022 on fig trees,displaying various fig mosaic disease symptoms.A total of 200 fig leaves and fruit samples were collected from various governorates in several Regions of Saudi Arabia including Riyadh,Tabuk,Hail,Qassim,Al-Jouf,Makkah,Jazan,Al-Madinah,Asir,and Northern Borders.These samples were tested by reverse transcription polymerase chain reaction(RT-PCR)with specific pairs of primers to assess the existence of Fig mosaic virus(FMV),Fig leaf mottle-associated virus 1(FLMaV-1),Fig leaf mottle-associated virus 2(FLMaV-2),Fig mild mottle-associated virus(FMMaV)and Fig fleck-associated virus(FFkaV).The results indicate that four viruses were found in mixed infections and tested positive.FMV was detected with a high infection rate of 46%followed by FLMaV-2 with an infection rate of 20%,FMMaV with an infection rate of 16%,and FLMaV-1 with an infection rate of 7%,respectively,while FFkaV was negative in all tested samples.Sequencing and phylogenetic analysis results showed that the FMV isolates shared 90.3%similarity with other FMV isolates,particularly those from Bosnia and Herzegovina(KU198368).While FLMaV-1 showed 92.5%similarity with the reference isolate FLMaV-1(KX397035),the isolates of FLMaV-2 exhibited 94.7%similarity with reference FLMaV-2 isolate(FN687742),and the isolate of FMMaV showed 94%similarity with reference FMMaV isolate(MG242131)based on sequence comparison.According to the RT-PCR results,FMV was effectively identified in all five fig varieties(Al Faiz Yellow,Asali,Brown Turkey,Iraqi,and Kaab Al-Ghazal).Contrarily,none of these varieties had FLMaV-1,FLMaV-2,or FMMaV.This study investigates the occurrence and economic impact of the viruses that infect fig trees in Saudi Arabia.This suggests that FMV is the primary virus infecting these fig varieties and there is no co-infection with the other tested viruses.These findings underscore the urgent need for implementing region-specific management strategies,such as breeding resistant cultivars,enforcing phytosanitary measures to limit virus spread,and prioritizing vector control to mitigate the economic impact of FMD on Saudi Arabia’s fig industry.展开更多
Forest carbon monitoring and reporting are critical for informing global climate change assessment. The regional estimates of forest carbon attached greater attention, to assess the role of forest in carbon mitigation...Forest carbon monitoring and reporting are critical for informing global climate change assessment. The regional estimates of forest carbon attached greater attention, to assess the role of forest in carbon mitigation. Here using field inventory, we examined the carbon sink and mitigation potential of monospecific Deodar forest in the Kumrat valley, of Hindu Kush Himalaya, Region of Pakistan, at a different elevation. The elevation of monospecific Deodar forest ranges from 2300 to 2700 m (a.s.l). We divided the forest into three elevation classes (that is 2300 - 2400 m (EI) 2400 - 2500 m (EII) and 2500 - 2700 m (EIII) a.s.l respectively). In each elevation class, we laid out 09 sample plots (33*33 m2) for measuring carbon values in living tree biomass (LT), soil (SC), litter, dead wood, cone (LDWC) and understory vegetation (USV). Our results showed that the carbon density at EI was 432.37 ± 277.96 Mg·C-1, while the carbon density at EII and EIII was 668.35 ± 323.94 and 1016.79 ± 542.99 Mg·C-1 respectively. Our finding revealed that the carbon mitigation potential of the forest increases with increasing elevation. Among the different elevation classes, EIII stored significantly higher carbon due to the dominance of mature, old age, larger trees, and the minimum anthropogenic disturbance, whereas EI stored statistically lower carbon because of maximum anthropogenic disturbance, which resulted in the removal of mature and over-mature trees. Furthermore, our correlation analysis between tree height and carbon stock and basal area and LT carbon, underlines that the basal area is the stronger predictor of LT carbon estimation than height. Overall our results highlight that deodar forest stored 716.94 ± 462.06 Mg?C·ha-1. However, the rehabilitation, preservation and sustainable management of disturb forest located at a lower elevation could considerably improve carbon mitigation potential.展开更多
The Bowen ratio(β) is used to quantify heat transfer from the land surface into the air, which is becoming a hot topic in research on the biogeophysical effects of land use and cover changes. The Three-River Headwate...The Bowen ratio(β) is used to quantify heat transfer from the land surface into the air, which is becoming a hot topic in research on the biogeophysical effects of land use and cover changes. The Three-River Headwaters(TRH), as a sensitive and fragile region, was selected as the study area. The β for 2001–2018 was estimated from the evapotranspiration product(ETMOD16) of MODIS and the net radiation of the land surface through the albedo from GLASS. The ETMOD16 data were evaluated against the observation data(ETOBS) at two alpine grassland flux towers obtained from ChinaFLUX. The interannual trend of the β was analyzed by multiple linear regression(MLR) and structure model(SEM) with the multiple factors of precipitation, temperature, humidity, albedo, and normalized difference vegetation index(NDVI, MOD09 Q1). The results show that the ETMOD16 values were significantly correlated with ETOBS, with a correlation coefficient above 0.70(P < 0.01) for the two sites. In 2001–2018, the regional mean β was 2.52 ± 0.77 for the whole grassland, and its spatial distribution gradually increased from the eastern to western region. The interannual β showed a downward trend with a slope of-0.025 and a multiple regression coefficient(R^(2)) of 0.21(P = 0.056). Most of the variability(51%) in the interannual β can be explained by the linear regression of the above multiple factors, and the temperature plays a dominant role for the whole region. The SEM analysis further shows that an increasing NDVI results in a decreasing albedo with a path coefficient of-0.57, because the albedo was negatively correlated with NDVI(R^(2) = 0.52, P < 0.01), which indicates a negative and indirect effect on β from vegetation restoration. An obvious warming climate was found to prompt more evapotranspiration, and restoring vegetation makes the land surface receive more radiation, which both resulted in a decreasing trend in the annual β. This study revealed the biogeophysical mechanisms of vegetation restoration under a changing climate, and demonstrated the Bowen ratio can be applied as an indicator of climate-regulating functions in ecosystem assessments.展开更多
文摘The common fig(Ficus carica L.),Moraceae family,is a commonly grown fruit tree in the Mediterranean region.Fig mosaic disease(FMD)poses a substantial threat to Saudi Arabia’s fig-producing economy.A survey was conducted during the two seasons of 2021 and 2022 on fig trees,displaying various fig mosaic disease symptoms.A total of 200 fig leaves and fruit samples were collected from various governorates in several Regions of Saudi Arabia including Riyadh,Tabuk,Hail,Qassim,Al-Jouf,Makkah,Jazan,Al-Madinah,Asir,and Northern Borders.These samples were tested by reverse transcription polymerase chain reaction(RT-PCR)with specific pairs of primers to assess the existence of Fig mosaic virus(FMV),Fig leaf mottle-associated virus 1(FLMaV-1),Fig leaf mottle-associated virus 2(FLMaV-2),Fig mild mottle-associated virus(FMMaV)and Fig fleck-associated virus(FFkaV).The results indicate that four viruses were found in mixed infections and tested positive.FMV was detected with a high infection rate of 46%followed by FLMaV-2 with an infection rate of 20%,FMMaV with an infection rate of 16%,and FLMaV-1 with an infection rate of 7%,respectively,while FFkaV was negative in all tested samples.Sequencing and phylogenetic analysis results showed that the FMV isolates shared 90.3%similarity with other FMV isolates,particularly those from Bosnia and Herzegovina(KU198368).While FLMaV-1 showed 92.5%similarity with the reference isolate FLMaV-1(KX397035),the isolates of FLMaV-2 exhibited 94.7%similarity with reference FLMaV-2 isolate(FN687742),and the isolate of FMMaV showed 94%similarity with reference FMMaV isolate(MG242131)based on sequence comparison.According to the RT-PCR results,FMV was effectively identified in all five fig varieties(Al Faiz Yellow,Asali,Brown Turkey,Iraqi,and Kaab Al-Ghazal).Contrarily,none of these varieties had FLMaV-1,FLMaV-2,or FMMaV.This study investigates the occurrence and economic impact of the viruses that infect fig trees in Saudi Arabia.This suggests that FMV is the primary virus infecting these fig varieties and there is no co-infection with the other tested viruses.These findings underscore the urgent need for implementing region-specific management strategies,such as breeding resistant cultivars,enforcing phytosanitary measures to limit virus spread,and prioritizing vector control to mitigate the economic impact of FMD on Saudi Arabia’s fig industry.
文摘Forest carbon monitoring and reporting are critical for informing global climate change assessment. The regional estimates of forest carbon attached greater attention, to assess the role of forest in carbon mitigation. Here using field inventory, we examined the carbon sink and mitigation potential of monospecific Deodar forest in the Kumrat valley, of Hindu Kush Himalaya, Region of Pakistan, at a different elevation. The elevation of monospecific Deodar forest ranges from 2300 to 2700 m (a.s.l). We divided the forest into three elevation classes (that is 2300 - 2400 m (EI) 2400 - 2500 m (EII) and 2500 - 2700 m (EIII) a.s.l respectively). In each elevation class, we laid out 09 sample plots (33*33 m2) for measuring carbon values in living tree biomass (LT), soil (SC), litter, dead wood, cone (LDWC) and understory vegetation (USV). Our results showed that the carbon density at EI was 432.37 ± 277.96 Mg·C-1, while the carbon density at EII and EIII was 668.35 ± 323.94 and 1016.79 ± 542.99 Mg·C-1 respectively. Our finding revealed that the carbon mitigation potential of the forest increases with increasing elevation. Among the different elevation classes, EIII stored significantly higher carbon due to the dominance of mature, old age, larger trees, and the minimum anthropogenic disturbance, whereas EI stored statistically lower carbon because of maximum anthropogenic disturbance, which resulted in the removal of mature and over-mature trees. Furthermore, our correlation analysis between tree height and carbon stock and basal area and LT carbon, underlines that the basal area is the stronger predictor of LT carbon estimation than height. Overall our results highlight that deodar forest stored 716.94 ± 462.06 Mg?C·ha-1. However, the rehabilitation, preservation and sustainable management of disturb forest located at a lower elevation could considerably improve carbon mitigation potential.
基金The National Key Basic Research and Development Program (2017YFC0503803)The National Natural Science Foundation of China (31971507)+1 种基金Qinghai Province Science and Technology Program (2018-ZJ-T09)CAS-Qinghai Province Joint Program on Three-River Headwaters National Park (YHZX-2020-07)。
文摘The Bowen ratio(β) is used to quantify heat transfer from the land surface into the air, which is becoming a hot topic in research on the biogeophysical effects of land use and cover changes. The Three-River Headwaters(TRH), as a sensitive and fragile region, was selected as the study area. The β for 2001–2018 was estimated from the evapotranspiration product(ETMOD16) of MODIS and the net radiation of the land surface through the albedo from GLASS. The ETMOD16 data were evaluated against the observation data(ETOBS) at two alpine grassland flux towers obtained from ChinaFLUX. The interannual trend of the β was analyzed by multiple linear regression(MLR) and structure model(SEM) with the multiple factors of precipitation, temperature, humidity, albedo, and normalized difference vegetation index(NDVI, MOD09 Q1). The results show that the ETMOD16 values were significantly correlated with ETOBS, with a correlation coefficient above 0.70(P < 0.01) for the two sites. In 2001–2018, the regional mean β was 2.52 ± 0.77 for the whole grassland, and its spatial distribution gradually increased from the eastern to western region. The interannual β showed a downward trend with a slope of-0.025 and a multiple regression coefficient(R^(2)) of 0.21(P = 0.056). Most of the variability(51%) in the interannual β can be explained by the linear regression of the above multiple factors, and the temperature plays a dominant role for the whole region. The SEM analysis further shows that an increasing NDVI results in a decreasing albedo with a path coefficient of-0.57, because the albedo was negatively correlated with NDVI(R^(2) = 0.52, P < 0.01), which indicates a negative and indirect effect on β from vegetation restoration. An obvious warming climate was found to prompt more evapotranspiration, and restoring vegetation makes the land surface receive more radiation, which both resulted in a decreasing trend in the annual β. This study revealed the biogeophysical mechanisms of vegetation restoration under a changing climate, and demonstrated the Bowen ratio can be applied as an indicator of climate-regulating functions in ecosystem assessments.
