After the outbreak of Dendrolimus superans Buter in 2002, many insect borers quickly invaded larch （Larix gmelinii Rupr.） forests in the Aershan of Inner Mongolia. Methods involved included setting sample plots, col...After the outbreak of Dendrolimus superans Buter in 2002, many insect borers quickly invaded larch （Larix gmelinii Rupr.） forests in the Aershan of Inner Mongolia. Methods involved included setting sample plots, collecting adults in iron traps and measuring areas of galleries to study the invasive sequence, their ecological niche and the extent of the different effects by the main insect borers to their hosts. The results showed that the damage of D. superans weakened L. gmelinii, first Ips subelongatus Motschulsky invaded, followed by Acanthocinus carinulatus Gebler, Monochamus urussovi Fisher and M. sutor L. After the outbreak of D. superans, the average density of longhorn beetles per L. gmelinii tree increased. The ecological niche of Ips subelongatus stretches almost from the base to the top of the trunk. The number of insects in older stands of L. gmelinii is larger than those in middle aged stands. They do not damage healthy trees of L. gmelinii. The ecological niche of A. carinulatus is higher in dead L. gmelinii trees than in weak ones. The degree of damage is directly proportional with age and depth of bark. M. urussovi mainly damages trunks below 4 m in weak trees; in dead trees they can do damage up to 6 m in height. M. sutor mainly damages trunks below 5 m in weak L. gmelinii trees; in dead trees they cause damage up to 7 m. Again, the degree of damage is directly proportional with age. None of the three species of longhorn beetles damage healthy L. gmelinii and younger trees. Among the main insect borers, the degree of damage caused by I. subelongatus is more serious than that of other insects.展开更多
The role of regional species diversity in large-scale species invasions has been largely controversial.On the one hand,it has been proposed that diversity may facilitate invasion(“diversity begets diversity”)because...The role of regional species diversity in large-scale species invasions has been largely controversial.On the one hand,it has been proposed that diversity may facilitate invasion(“diversity begets diversity”)because regions with higher diversity may indicate favorable conditions for many more species.On the other hand,high diversity may indicate high levels of niche occupation,thus making it more difficult for new species to invade.In the past,invasion biologists have evaluated how regional native and exotic richness are related.Here,we test whether the range size of exotic species may be constrained by regional native richness using plant data from three continental regions in the Northern Hemisphere,i.e.,Europe,Eastern Asia,and North America.We found that regional native plant diversity is inversely related to the range size of exotic species.This result may be due to stronger species interactions such as competition in species-rich habitats that limit the establishment and spread of exotic species.展开更多
Agriculture intensification,marked by the generalization of crop monoculture,by the increase in plot size and by the reduction of plant diversity,has led to huge decline in wildlife in European farmlands.In such habit...Agriculture intensification,marked by the generalization of crop monoculture,by the increase in plot size and by the reduction of plant diversity,has led to huge decline in wildlife in European farmlands.In such habitat,re-search has long been biased towards birds and invertebrates,while very few studies have investigated the ef-fect on small mammals.Considering the European hamster,Cricetus cricetus,we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals.We suggest that only a multidisciplinary approach will allow exploration of these effects,combining experimental laboratory work on captive-bred animals with the monitoring of wild individuals.In particular,individual energy balance has to be investigated and measured as accurately as possi-ble,through either biochemical or bio-logging techniques.It is,indeed,the most affected physiological trait in a changing environment,as it determines both the reproductive output and the survival of the individual.We also discuss the inconvenience of capture-release approaches for such an endangered species and emphasize the dis-turbance that experimental protocols could impose on the hamster.展开更多
文摘After the outbreak of Dendrolimus superans Buter in 2002, many insect borers quickly invaded larch （Larix gmelinii Rupr.） forests in the Aershan of Inner Mongolia. Methods involved included setting sample plots, collecting adults in iron traps and measuring areas of galleries to study the invasive sequence, their ecological niche and the extent of the different effects by the main insect borers to their hosts. The results showed that the damage of D. superans weakened L. gmelinii, first Ips subelongatus Motschulsky invaded, followed by Acanthocinus carinulatus Gebler, Monochamus urussovi Fisher and M. sutor L. After the outbreak of D. superans, the average density of longhorn beetles per L. gmelinii tree increased. The ecological niche of Ips subelongatus stretches almost from the base to the top of the trunk. The number of insects in older stands of L. gmelinii is larger than those in middle aged stands. They do not damage healthy trees of L. gmelinii. The ecological niche of A. carinulatus is higher in dead L. gmelinii trees than in weak ones. The degree of damage is directly proportional with age and depth of bark. M. urussovi mainly damages trunks below 4 m in weak trees; in dead trees they can do damage up to 6 m in height. M. sutor mainly damages trunks below 5 m in weak L. gmelinii trees; in dead trees they cause damage up to 7 m. Again, the degree of damage is directly proportional with age. None of the three species of longhorn beetles damage healthy L. gmelinii and younger trees. Among the main insect borers, the degree of damage caused by I. subelongatus is more serious than that of other insects.
文摘The role of regional species diversity in large-scale species invasions has been largely controversial.On the one hand,it has been proposed that diversity may facilitate invasion(“diversity begets diversity”)because regions with higher diversity may indicate favorable conditions for many more species.On the other hand,high diversity may indicate high levels of niche occupation,thus making it more difficult for new species to invade.In the past,invasion biologists have evaluated how regional native and exotic richness are related.Here,we test whether the range size of exotic species may be constrained by regional native richness using plant data from three continental regions in the Northern Hemisphere,i.e.,Europe,Eastern Asia,and North America.We found that regional native plant diversity is inversely related to the range size of exotic species.This result may be due to stronger species interactions such as competition in species-rich habitats that limit the establishment and spread of exotic species.
文摘Agriculture intensification,marked by the generalization of crop monoculture,by the increase in plot size and by the reduction of plant diversity,has led to huge decline in wildlife in European farmlands.In such habitat,re-search has long been biased towards birds and invertebrates,while very few studies have investigated the ef-fect on small mammals.Considering the European hamster,Cricetus cricetus,we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals.We suggest that only a multidisciplinary approach will allow exploration of these effects,combining experimental laboratory work on captive-bred animals with the monitoring of wild individuals.In particular,individual energy balance has to be investigated and measured as accurately as possi-ble,through either biochemical or bio-logging techniques.It is,indeed,the most affected physiological trait in a changing environment,as it determines both the reproductive output and the survival of the individual.We also discuss the inconvenience of capture-release approaches for such an endangered species and emphasize the dis-turbance that experimental protocols could impose on the hamster.
