The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource uti...The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource utilization, including partitioning, in degraded wetlands has become a hot issue in ecological studies of wintering waterbirds. In order to have an insight into the habitat utilization and resource partitioning between a Hooded Crane(Grus monacha) population and the guild of three goose species, i.e., Anser fabalis, A. albifrons and A. erythropus wintering in lake wetlands, we carried out a study at Shengjin Lake National Nature Reserve from November 2011 to April 2012. We surveyed the Hooded Cranes and goose guild foraging in various habitats during the wintering periods with a combined method of fixed route searching and fixed site observations. Resource partitioning was studied by means of calculating habitat utilization rates and the width and overlap of spatial niches. The results showed that the habitat utilization rate and the width of spatial niches of the Hooded Crane population and goose guild shifted with the season. The habitat utilization rates of the cranes in grasslands were high at all three wintering stages. The habitat utilization rates were 0.454, 0.435 and 0.959 respectively for the Hooded Cranes and 0.627, 0.491 and 0.616 for the goose guild. This suggests that the overlap in grasslands was higher between cranes and goose guild. Most habitats were accessible at the middle stage, so the width of the spatial niche of the cranes(1.099) and goose guild(1.133) both reached their peak at this stage. The greatest niche overlap was 0.914 for these two groups at the late stage, followed by 0.906 at the middle stage and the smallest was 0.854 at the early stage. Ecological response to the changes in habitats of wintering waterbirds was clearly shown in the dynamic variations of the niche of both the Hooded Cranes and the three goose species. Coexistence among waterbirds was achieved by regulation of niche width to reduce niche overlap and relieve interspecific resource partitioning.展开更多
[Objective] This study aimed to explore the biological habits of Scirothrips dorsalis Hood and methods for controlling this pest. [Method] From 2009 to 2011, the biological habits of Scirothrips dorsalis Hood and the ...[Objective] This study aimed to explore the biological habits of Scirothrips dorsalis Hood and methods for controlling this pest. [Method] From 2009 to 2011, the biological habits of Scirothrips dorsalis Hood and the regularity of its occurrence on mangoes were investigated at the experimental base of the Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences and Shuanghongqiao Mango Orchard in Baoshan, Yunnan Province. In addition, a field trial on the effects of four medicaments on controlling this pest was also conducted. [Result] The result showed that Scirothrips dorsalis Hood completed 10-12 genera- tions per year in Baoshan area, and the peak period of its incidence was from February to April. The results of the pest control testing showed that at 0.05 level, there were significant differences of effect on pest controlling among the treatments I, II and IV, and the treatment III showed significant differences of controlling effect with the treatment IV, while no significant differences with either the treatment I or the treatment II; at 0.01 level, there was no significant difference among the treat- ments I, II and III, while all the three treatments showed significant differences with treatment IV. [Conclusion] This study revealed that the occurrence and the severity of Scirothrips dorsalis Hood on mangoes in Baoshan, Yunnan Province. In addition, pesticides with certain efficacy on controlling Scirothrips dorsalis Hood were screened, which provides more options for fruit growers to control this pest on mangoes.展开更多
波达方向(Direction of Arrival,DOA)估计是阵列观测数据研究领域的一个基本问题.对于观测数据服从复椭球对称分布的应用场景,现有的方法多采用l1-范数惩罚项来实现信号波达方向的稀疏估计,其中的l1-范数惩罚项仅考虑信号的稀疏性而没...波达方向(Direction of Arrival,DOA)估计是阵列观测数据研究领域的一个基本问题.对于观测数据服从复椭球对称分布的应用场景,现有的方法多采用l1-范数惩罚项来实现信号波达方向的稀疏估计,其中的l1-范数惩罚项仅考虑信号的稀疏性而没有考虑信号的多样性,从而造成这些估计方法一般将弱信号(具有较低功率的信号)略去,可能无法准确地估计弱信号的波达方向.为解决这个问题,本文通过引入一个组合范数惩罚项构建了一个新的估计(模型)方法,其中的组合范数惩罚项是l1-范数惩罚项与l2-范数平方惩罚项的线性组合,其组合系数(惩罚参数)互不相关,l2-范数平方惩罚项则可以保留弱信号的多样性.然后,本文基于Majorization-Minimization(MM)算法设计了模型的求解算法,并证明该方法是收敛的.数值实验表明,相较于那些基于l1-惩罚项的估计方法,本方法具有更高的精度.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.31172117)the Graduate Student Innovation Research Projects of Anhui University(Grant No.yqh100118)the Anhui Academic and Technical Leader Fund
文摘The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource utilization, including partitioning, in degraded wetlands has become a hot issue in ecological studies of wintering waterbirds. In order to have an insight into the habitat utilization and resource partitioning between a Hooded Crane(Grus monacha) population and the guild of three goose species, i.e., Anser fabalis, A. albifrons and A. erythropus wintering in lake wetlands, we carried out a study at Shengjin Lake National Nature Reserve from November 2011 to April 2012. We surveyed the Hooded Cranes and goose guild foraging in various habitats during the wintering periods with a combined method of fixed route searching and fixed site observations. Resource partitioning was studied by means of calculating habitat utilization rates and the width and overlap of spatial niches. The results showed that the habitat utilization rate and the width of spatial niches of the Hooded Crane population and goose guild shifted with the season. The habitat utilization rates of the cranes in grasslands were high at all three wintering stages. The habitat utilization rates were 0.454, 0.435 and 0.959 respectively for the Hooded Cranes and 0.627, 0.491 and 0.616 for the goose guild. This suggests that the overlap in grasslands was higher between cranes and goose guild. Most habitats were accessible at the middle stage, so the width of the spatial niche of the cranes(1.099) and goose guild(1.133) both reached their peak at this stage. The greatest niche overlap was 0.914 for these two groups at the late stage, followed by 0.906 at the middle stage and the smallest was 0.854 at the early stage. Ecological response to the changes in habitats of wintering waterbirds was clearly shown in the dynamic variations of the niche of both the Hooded Cranes and the three goose species. Coexistence among waterbirds was achieved by regulation of niche width to reduce niche overlap and relieve interspecific resource partitioning.
基金Supported by the Special Fund for the Industrial Science and Technology Construction of Department of Agriculture(201202092-6)~~
文摘[Objective] This study aimed to explore the biological habits of Scirothrips dorsalis Hood and methods for controlling this pest. [Method] From 2009 to 2011, the biological habits of Scirothrips dorsalis Hood and the regularity of its occurrence on mangoes were investigated at the experimental base of the Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences and Shuanghongqiao Mango Orchard in Baoshan, Yunnan Province. In addition, a field trial on the effects of four medicaments on controlling this pest was also conducted. [Result] The result showed that Scirothrips dorsalis Hood completed 10-12 genera- tions per year in Baoshan area, and the peak period of its incidence was from February to April. The results of the pest control testing showed that at 0.05 level, there were significant differences of effect on pest controlling among the treatments I, II and IV, and the treatment III showed significant differences of controlling effect with the treatment IV, while no significant differences with either the treatment I or the treatment II; at 0.01 level, there was no significant difference among the treat- ments I, II and III, while all the three treatments showed significant differences with treatment IV. [Conclusion] This study revealed that the occurrence and the severity of Scirothrips dorsalis Hood on mangoes in Baoshan, Yunnan Province. In addition, pesticides with certain efficacy on controlling Scirothrips dorsalis Hood were screened, which provides more options for fruit growers to control this pest on mangoes.
文摘波达方向(Direction of Arrival,DOA)估计是阵列观测数据研究领域的一个基本问题.对于观测数据服从复椭球对称分布的应用场景,现有的方法多采用l1-范数惩罚项来实现信号波达方向的稀疏估计,其中的l1-范数惩罚项仅考虑信号的稀疏性而没有考虑信号的多样性,从而造成这些估计方法一般将弱信号(具有较低功率的信号)略去,可能无法准确地估计弱信号的波达方向.为解决这个问题,本文通过引入一个组合范数惩罚项构建了一个新的估计(模型)方法,其中的组合范数惩罚项是l1-范数惩罚项与l2-范数平方惩罚项的线性组合,其组合系数(惩罚参数)互不相关,l2-范数平方惩罚项则可以保留弱信号的多样性.然后,本文基于Majorization-Minimization(MM)算法设计了模型的求解算法,并证明该方法是收敛的.数值实验表明,相较于那些基于l1-惩罚项的估计方法,本方法具有更高的精度.
