Anthropogenic disturbances are widespread in tropical forests and influence the species composition in the overstory.However,the impacts of historical disturbance on tropical forest overstory recovery are unclear due ...Anthropogenic disturbances are widespread in tropical forests and influence the species composition in the overstory.However,the impacts of historical disturbance on tropical forest overstory recovery are unclear due to a lack of disturbance data,and previous studies have focused on understory species.In this study,the purpose was to deter-mine the influence of historical disturbance on the diver-sity,composition and regeneration of overstory species in present forests.In the 20-ha Xishuangbanna tropical sea-sonal rainforest dynamics plot in southwestern China,the historical disturbance boundaries were delineated based on panchromatic photographs from 1965.Factors that drove species clustering in the overstory layer(DBH≥40 cm)were analyzed and the abundance,richness and composition of these species were compared among different tree groups based on multiple regression tree analysis.The coefficient of variation of the brightness value in historical panchro-matic photographs from 1965 was the primary driver of spe-cies clustering in the overstory layer.The abundance and richness of overstory species throughout the regeneration process were similar,but species composition was always different.Although the proportion of large-seeded and vigorous-sprouting species showed no significant differ-ence between disturbed and undisturbed forests in the tree-let layer(DBH<20 cm),the difference became significant when DBH increased.The findings highlight that historical disturbances have strong legacy effects on functional group composition in the overstory and the recovery of overstory species was multidimensional.Functional group composi-tion can better indicate the dynamics of overstory species replacement during secondary succession.展开更多
Neighborhood effects on seed predation and dispersal processes are usually seed-characteristic-dependent;however,how seeds with certain characteristics affect the foraging behavior of rodents in relation to other seed...Neighborhood effects on seed predation and dispersal processes are usually seed-characteristic-dependent;however,how seeds with certain characteristics affect the foraging behavior of rodents in relation to other seeds nearby is unclear.Because large differences in seed characteristics between neighboring seeds may lead to significant differences in rodent foraging preferences,we hypothesized that neighborhood effects were more likely to be detected when paired seeds differed in seed characteristics.We investigated the foraging decisions of two rodent species,the red spiny rat Maxomys surifer and the Chinese white-bellied rat Niviventer confucianus,in semi-natural enclosures by presenting them with artificial seeds containing different levels of tannin(0,3%,and 6%tannin).Both rodents showed similar preferences and preferentially consumed high-tannin seeds(6%tannin)and scatter hoarded low-tannin seeds(0 tannin).The scatter hoarding of low-tannin(0 tannin)and high-tannin(6%tannin)seeds was significantly higher when these seeds were neighboring higher-tannin seeds than when they neighbored lowertannin seeds,whereas the scatter hoarding of intermediate-tannin seeds(3%tannin)varied little when they had different neighbors.High-tannin-seed(6%tannin)scatter hoarding was lowest when they neighbored low-tannin seeds(0 tannin),while low-tannin-seed(0 tannin)scatter hoarding was highest when they neighbored high-tannin seeds(6%tannin).Therefore,the seeds that the rodents scatter hoarded were next to(neighbored)seeds that they preferred to eat immediately,and vice versa.Our findings suggest that seed neighborhood effects affect rodent foraging behavior and the relationship between plants and rodents,and may have a profound effect on the regeneration and spatial structure of plant communities.展开更多
基金supported by the Natural Science Foundation of Yunnan Province(Grant No:202301AT070356)the Open Fund of the Key Laboratory of Tropical Forest Ecology,Chinese Academy of Sciences,National Science Foundation of China(Grant No.32061123003)+1 种基金the Joint Fund of the National Natural Science Foundation of China-Yunnan Province(Grant No.U1902203)the Field Station Foundation of the Chinese Academy of Sciences.
文摘Anthropogenic disturbances are widespread in tropical forests and influence the species composition in the overstory.However,the impacts of historical disturbance on tropical forest overstory recovery are unclear due to a lack of disturbance data,and previous studies have focused on understory species.In this study,the purpose was to deter-mine the influence of historical disturbance on the diver-sity,composition and regeneration of overstory species in present forests.In the 20-ha Xishuangbanna tropical sea-sonal rainforest dynamics plot in southwestern China,the historical disturbance boundaries were delineated based on panchromatic photographs from 1965.Factors that drove species clustering in the overstory layer(DBH≥40 cm)were analyzed and the abundance,richness and composition of these species were compared among different tree groups based on multiple regression tree analysis.The coefficient of variation of the brightness value in historical panchro-matic photographs from 1965 was the primary driver of spe-cies clustering in the overstory layer.The abundance and richness of overstory species throughout the regeneration process were similar,but species composition was always different.Although the proportion of large-seeded and vigorous-sprouting species showed no significant differ-ence between disturbed and undisturbed forests in the tree-let layer(DBH<20 cm),the difference became significant when DBH increased.The findings highlight that historical disturbances have strong legacy effects on functional group composition in the overstory and the recovery of overstory species was multidimensional.Functional group composi-tion can better indicate the dynamics of overstory species replacement during secondary succession.
基金the project of the National Natural Science Foundation of China(31872236)the Science and Technology Planning Project of Yunnan Science and Technology Department(2018FB038)the Opening Fund of Key Laboratory of Poyang Lake Wetland and Watershed Research(Jiangxi Normal University),Ministry of Education(grant no.PK2018005).
文摘Neighborhood effects on seed predation and dispersal processes are usually seed-characteristic-dependent;however,how seeds with certain characteristics affect the foraging behavior of rodents in relation to other seeds nearby is unclear.Because large differences in seed characteristics between neighboring seeds may lead to significant differences in rodent foraging preferences,we hypothesized that neighborhood effects were more likely to be detected when paired seeds differed in seed characteristics.We investigated the foraging decisions of two rodent species,the red spiny rat Maxomys surifer and the Chinese white-bellied rat Niviventer confucianus,in semi-natural enclosures by presenting them with artificial seeds containing different levels of tannin(0,3%,and 6%tannin).Both rodents showed similar preferences and preferentially consumed high-tannin seeds(6%tannin)and scatter hoarded low-tannin seeds(0 tannin).The scatter hoarding of low-tannin(0 tannin)and high-tannin(6%tannin)seeds was significantly higher when these seeds were neighboring higher-tannin seeds than when they neighbored lowertannin seeds,whereas the scatter hoarding of intermediate-tannin seeds(3%tannin)varied little when they had different neighbors.High-tannin-seed(6%tannin)scatter hoarding was lowest when they neighbored low-tannin seeds(0 tannin),while low-tannin-seed(0 tannin)scatter hoarding was highest when they neighbored high-tannin seeds(6%tannin).Therefore,the seeds that the rodents scatter hoarded were next to(neighbored)seeds that they preferred to eat immediately,and vice versa.Our findings suggest that seed neighborhood effects affect rodent foraging behavior and the relationship between plants and rodents,and may have a profound effect on the regeneration and spatial structure of plant communities.
