The spatial distribution of plant species reveals how members of a population are horizontally organized in the environment. Individuals at different development stages can be influenced differently by abiotic and bio...The spatial distribution of plant species reveals how members of a population are horizontally organized in the environment. Individuals at different development stages can be influenced differently by abiotic and biotic factors because they are temporally separated. This may cause changes in spatial patterns in ontogenetic stages. The objectives of this study were to verify the pattern of spatial distribution of saplings and adults in Dalbergia cearensis Ducke and relate it to the pattern of seed dispersal. In two areas of 4.0 ha each, located in a Private Natural Heritage Reserve (RPPN) “Não Me Deixes”, there were counted all saplings and adults. This data were applied to the spatial analysis by distance indices, using the software Sadie Shell, version 8.0. The aggregation index (Ia) of adults was significant for both areas and showed aggregated distribution. D. cearensis saplings showed an aggregated distribution in the area I and area II. The dispersion distance was proportional for both areas, and the highest proportion of seeds was 10 - 20 m away from the center of the aggregation. Spatial analysis by distance indices showed an aggregated spatial distribution pattern for saplings and adults of D. cearensis.展开更多
Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns o...Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre-harvest corn fields, we further examined both spatial and temporal patterns of cob- and kernel- feeding insect damage, and aflatoxin level with two samplings at pre-harvest in 2008 and 2009. The feeding damage by each of the ear/kernel-feeding insects （i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs） and maize weevil population were assessed at each grid point with five ears. Sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevils tended toward an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil number were more closely associated with aflatoxin level than was corn earworm damage. In addition, the indices of spatial-temporal association （χ） demonstrated that the number of maize weevils was associated between the first （4 weeks pre-harvest） and second （1 week pre-harvest） samplings in both years on all fields. In contrast, corn earworm damage between the first and second samplings from the field on the Belflower Farm, and aflatoxin level and corn earworm damage from the field on the Lang Farm were dissociated in 2009.展开更多
Soil invertebrates and heavy metal concentrations are heterogeneously distributed in the soil of steppe plots surrounding an iron mining enterprise in southern Russia. This study assesses whether patches of high soil ...Soil invertebrates and heavy metal concentrations are heterogeneously distributed in the soil of steppe plots surrounding an iron mining enterprise in southern Russia. This study assesses whether patches of high soil invertebrate abundance coincide with patches of low concentrations of pollutants. For this aim, spatial analysis by distance indices （SADIE） was applied. Three valleys in Belogorye Nature Reserve were chosen. One valley faced the tailing pond to the north and the other two faced south-east or south-west. Two sampling plots were chosen in each valley, 60 m apart from each other. On every plot 16 soil cores were collected from a grid of 4 × 4 units with a 5-m distance between each sample unit. Each soil core had an area of 76 cm2 and was 12-15 cm deep. All macroinvertebrates were hand-sorted and identified to family. Abundance of soil invertebrates was not controlled by patches of metal concentration in the soil. Epigaeic groups, like insects and other invertebrates inhabiting the litter layer, were not directly associated with local parameters of the soil. On the contrary, belowground invertebrate abundance （elaterid larvae and earthworms） showed significant dissociation with some heavy metal （Fe, Pb, Zn） concentrations in the soil. The patchiness of soil pollution may act as a leading factor ofbelowground soil invertebrate distribution. The spatial structure of animal populations in industrially transformed soils needs further research.展开更多
文摘The spatial distribution of plant species reveals how members of a population are horizontally organized in the environment. Individuals at different development stages can be influenced differently by abiotic and biotic factors because they are temporally separated. This may cause changes in spatial patterns in ontogenetic stages. The objectives of this study were to verify the pattern of spatial distribution of saplings and adults in Dalbergia cearensis Ducke and relate it to the pattern of seed dispersal. In two areas of 4.0 ha each, located in a Private Natural Heritage Reserve (RPPN) “Não Me Deixes”, there were counted all saplings and adults. This data were applied to the spatial analysis by distance indices, using the software Sadie Shell, version 8.0. The aggregation index (Ia) of adults was significant for both areas and showed aggregated distribution. D. cearensis saplings showed an aggregated distribution in the area I and area II. The dispersion distance was proportional for both areas, and the highest proportion of seeds was 10 - 20 m away from the center of the aggregation. Spatial analysis by distance indices showed an aggregated spatial distribution pattern for saplings and adults of D. cearensis.
文摘Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre-harvest corn fields, we further examined both spatial and temporal patterns of cob- and kernel- feeding insect damage, and aflatoxin level with two samplings at pre-harvest in 2008 and 2009. The feeding damage by each of the ear/kernel-feeding insects （i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs） and maize weevil population were assessed at each grid point with five ears. Sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevils tended toward an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil number were more closely associated with aflatoxin level than was corn earworm damage. In addition, the indices of spatial-temporal association （χ） demonstrated that the number of maize weevils was associated between the first （4 weeks pre-harvest） and second （1 week pre-harvest） samplings in both years on all fields. In contrast, corn earworm damage between the first and second samplings from the field on the Belflower Farm, and aflatoxin level and corn earworm damage from the field on the Lang Farm were dissociated in 2009.
文摘Soil invertebrates and heavy metal concentrations are heterogeneously distributed in the soil of steppe plots surrounding an iron mining enterprise in southern Russia. This study assesses whether patches of high soil invertebrate abundance coincide with patches of low concentrations of pollutants. For this aim, spatial analysis by distance indices （SADIE） was applied. Three valleys in Belogorye Nature Reserve were chosen. One valley faced the tailing pond to the north and the other two faced south-east or south-west. Two sampling plots were chosen in each valley, 60 m apart from each other. On every plot 16 soil cores were collected from a grid of 4 × 4 units with a 5-m distance between each sample unit. Each soil core had an area of 76 cm2 and was 12-15 cm deep. All macroinvertebrates were hand-sorted and identified to family. Abundance of soil invertebrates was not controlled by patches of metal concentration in the soil. Epigaeic groups, like insects and other invertebrates inhabiting the litter layer, were not directly associated with local parameters of the soil. On the contrary, belowground invertebrate abundance （elaterid larvae and earthworms） showed significant dissociation with some heavy metal （Fe, Pb, Zn） concentrations in the soil. The patchiness of soil pollution may act as a leading factor ofbelowground soil invertebrate distribution. The spatial structure of animal populations in industrially transformed soils needs further research.
