P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height ... more P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height and over 1.2 m or more in dbh in its native range in the eastern USA, though south-western varieties are much smaller. However, where introduced in Central Europe, P. serotina is mostly a shrub, only rarely a tree up to 20 m in height. Black cherry was among the first American trees to be cultivated as an ornamental in European gardens, introduced to England in 1629. In many places it has become naturalized and appears to be highly invasive. The invasive behaviour of this species in several northern and central European countries should be taken into account when considering future introductions to moist, temperate climates.
Plants are connected to habitats by functional traits which are filtered by environmental gradien... more Plants are connected to habitats by functional traits which are filtered by environmental gradients. Since tree species composition in the forest canopy can influence ecosystem processes by changing resource availability, litter accumulation, and soil nutrient content, we hypothesised that non-native invasive trees can establish new environmental filters on the understorey communities. In the hardwood floodplain forests in Northern Italy, the invasive trees Robinia pseudoacacia L. and Prunus serotina Ehrh. are the dominant canopy species. We used trait data assembled from databases and iterative RLQ analysis to identify a parsimonious set of functional traits responding to environmental variables (soil, light availability, disturbance, and stand structure) and the dominant native and invasive canopy species. Then, RLQ and fourth-corner analysis was conducted to investigate the joint structure between macro-environmental variables and species traits and functional groups were identified. The trait composition of the herb-layer was significantly related to the main environmental gradients and the presence of the invaders in the canopy showed significant relationships with several traits. In particular, the presence of P. serotina may mitigate or even erase the effect of disturbances, maintaining a stable forest microclimate and thus favouring ‘true’ forest species, while R. pseudoacacia may slow down forest succession and regeneration by establishing new stable associations with a graminoid-dominated understorey. The impact of the two invasive trees on herb layer composition appears to differ, indicating that different management and control strategies may be needed.
In hardwood floodplain forests of the North Italian Po Plain the non-native and light-demanding t... more In hardwood floodplain forests of the North Italian Po Plain the non-native and light-demanding tree species Prunus serotina Ehrh. and Robinia pseudoacacia L. coexist with the native tree species Carpinus betulus L., Quercus robur L., and Ulmus minor Mill. In order to identify the factors controlling the establishment of seedlings of these species, we focused on the scale of micro-plots, which provide safe sites for tree species regeneration. We used seedling and sapling counts as the response variable. For modelling the seedling regeneration in relation to a multivariate set of 15 measured soil and stand characteristics, a hurdle negative binomial model was applied and then compared with a non-metric multidimensional scaling ordination, visualising the relationships between the regenerating species and the environmental parameters. In general, it could be shown that there are species-specific differences in the requirements for seedling regeneration between the five target species, and that the most important parameters affecting seedling establishment were the availability of potential seed sources, soil humidity, and light availability. Q. robur and C. betulus showed a wide ecological range regarding soil humidity, whereas U. minor was restricted to moister soils, and the two non-native species only occurred on dry soils. In addition, R. pseudoacacia and Q. robur regenerated very scarcely under the closed canopy inside the stands and were highly dependent on large scale disturbance events. After a disturbance, the presence of R. pseudoacacia in the canopy promoted the seedling regeneration of Q. robur. P. serotina was found to regenerate frequently in the closed forest and to persist for a long time under shade, but also needs forest gaps to establish in the canopy. We believe that P. serotina was wrongly classified as a shade-intolerant species in the past. We suggest that it is a competitive invader in a broad range of resource availability. In conclusion, with regard to the further forest development, it could be assumed that the absence of disturbance events resulting in large openings leads to a reduction in the number of P. serotina, R. pseudoacacia, and Q. robur individuals during succession. Nevertheless, disturbances on wetter soils, e.g. related to the natural river dynamics, will clearly favour the seedling regeneration of Q. robur compared to the non-native species, which are generally limited to the drier sites of the floodplain forests.
P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height ... more P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height and over 1.2 m or more in dbh in its native range in the eastern USA, though south-western varieties are much smaller. However, where introduced in Central Europe, P. serotina is mostly a shrub, only rarely a tree up to 20 m in height. Black cherry was among the first American trees to be cultivated as an ornamental in European gardens, introduced to England in 1629. In many places it has become naturalized and appears to be highly invasive. The invasive behaviour of this species in several northern and central European countries should be taken into account when considering future introductions to moist, temperate climates.
AimTo determine biotic and abiotic controls on pine invasion globally within six ecoregions that ... more AimTo determine biotic and abiotic controls on pine invasion globally within six ecoregions that include both introduced and native ranges.LocationsRío Negro province, Argentina; Aysén and Araucanía regions, Chile; South Island (two ecoregions), New Zealand; Greater Yellowstone ecosystem, USA.MethodsWe quantified tree abundance and size across invasion fronts of the widespread invasive tree species Pinus contorta at each of the nine sites, encompassing both the native and introduced range. We also determined the relative importance of propagule pressure, abiotic characteristics and biotic factors for invasion success. Finally, key plant population metrics such as individual tree growth rates and reproductive effort were compared between native and introduced ranges.ResultsPinus contorta density decreased with increasing distance from source population in all cases, but the importance and shape of this relationship differed among sites due, primarily to biotic factors. For example, a...
Plants are connected to habitats by functional traits which are filtered by environmental gradien... more Plants are connected to habitats by functional traits which are filtered by environmental gradients. Since tree species composition in the forest canopy can influence ecosystem processes by changing resource availability, litter accumulation, and soil nutrient content, we hypothesised that non-native invasive trees can establish new environmental filters on the understorey communities. In the hardwood floodplain forests in Northern Italy, the invasive trees Robinia pseudoacacia L. and Prunus serotina Ehrh. are the dominant canopy species. We used trait data assembled from databases and iterative RLQ analysis to identify a parsimonious set of functional traits responding to environmental variables (soil, light availability, disturbance, and stand structure) and the dominant native and invasive canopy species. Then, RLQ and fourth-corner analysis was conducted to investigate the joint structure between macro-environmental variables and species traits and functional groups were identified. The trait composition of the herb-layer was significantly related to the main environmental gradients and the presence of the invaders in the canopy showed significant relationships with several traits. In particular, the presence of P. serotina may mitigate or even erase the effect of disturbances, maintaining a stable forest microclimate and thus favouring ‘true’ forest species, while R. pseudoacacia may slow down forest succession and regeneration by establishing new stable associations with a graminoid-dominated understorey. The impact of the two invasive trees on herb layer composition appears to differ, indicating that different management and control strategies may be needed.
Species pool hypothesis is broadly known and frequently tested in various regions and vegetation ... more Species pool hypothesis is broadly known and frequently tested in various regions and vegetation types. However it has not been tested in the arid Xinjiang region of China due to lack of data. Here with systematic data from references and field survey, we comprehensively examined species pool hypothesis in this region. Took species richness in 0.1° × 0.1° grid cells as regional species richness (RSR) which were obtained from the distribution maps of vascular plant species, and took species diversity of 190 and 103 plots in forest and grassland biomes across Xinjiang as local species richness (LSR), together with the digitalized soil pH and climate data, we tested the species pool hypothesis in this region. We found that: (1) the average RSR was higher in mountains than that in basins and it was negatively correlated with soil pH in mountains while positively correlated with soil pH in basins in Xinjiang; (2) RSR showed a positive correlation with mean annual precipitation (MAP) whil...
P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height ... more P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height and over 1.2 m or more in dbh in its native range in the eastern USA, though south-western varieties are much smaller. However, where introduced in Central Europe, P. serotina is mostly a shrub, only rarely a tree up to 20 m in height. Black cherry was among the first American trees to be cultivated as an ornamental in European gardens, introduced to England in 1629. In many places it has become naturalized and appears to be highly invasive. The invasive behaviour of this species in several northern and central European countries should be taken into account when considering future introductions to moist, temperate climates.
Plants are connected to habitats by functional traits which are filtered by environmental gradien... more Plants are connected to habitats by functional traits which are filtered by environmental gradients. Since tree species composition in the forest canopy can influence ecosystem processes by changing resource availability, litter accumulation, and soil nutrient content, we hypothesised that non-native invasive trees can establish new environmental filters on the understorey communities. In the hardwood floodplain forests in Northern Italy, the invasive trees Robinia pseudoacacia L. and Prunus serotina Ehrh. are the dominant canopy species. We used trait data assembled from databases and iterative RLQ analysis to identify a parsimonious set of functional traits responding to environmental variables (soil, light availability, disturbance, and stand structure) and the dominant native and invasive canopy species. Then, RLQ and fourth-corner analysis was conducted to investigate the joint structure between macro-environmental variables and species traits and functional groups were identified. The trait composition of the herb-layer was significantly related to the main environmental gradients and the presence of the invaders in the canopy showed significant relationships with several traits. In particular, the presence of P. serotina may mitigate or even erase the effect of disturbances, maintaining a stable forest microclimate and thus favouring ‘true’ forest species, while R. pseudoacacia may slow down forest succession and regeneration by establishing new stable associations with a graminoid-dominated understorey. The impact of the two invasive trees on herb layer composition appears to differ, indicating that different management and control strategies may be needed.
In hardwood floodplain forests of the North Italian Po Plain the non-native and light-demanding t... more In hardwood floodplain forests of the North Italian Po Plain the non-native and light-demanding tree species Prunus serotina Ehrh. and Robinia pseudoacacia L. coexist with the native tree species Carpinus betulus L., Quercus robur L., and Ulmus minor Mill. In order to identify the factors controlling the establishment of seedlings of these species, we focused on the scale of micro-plots, which provide safe sites for tree species regeneration. We used seedling and sapling counts as the response variable. For modelling the seedling regeneration in relation to a multivariate set of 15 measured soil and stand characteristics, a hurdle negative binomial model was applied and then compared with a non-metric multidimensional scaling ordination, visualising the relationships between the regenerating species and the environmental parameters. In general, it could be shown that there are species-specific differences in the requirements for seedling regeneration between the five target species, and that the most important parameters affecting seedling establishment were the availability of potential seed sources, soil humidity, and light availability. Q. robur and C. betulus showed a wide ecological range regarding soil humidity, whereas U. minor was restricted to moister soils, and the two non-native species only occurred on dry soils. In addition, R. pseudoacacia and Q. robur regenerated very scarcely under the closed canopy inside the stands and were highly dependent on large scale disturbance events. After a disturbance, the presence of R. pseudoacacia in the canopy promoted the seedling regeneration of Q. robur. P. serotina was found to regenerate frequently in the closed forest and to persist for a long time under shade, but also needs forest gaps to establish in the canopy. We believe that P. serotina was wrongly classified as a shade-intolerant species in the past. We suggest that it is a competitive invader in a broad range of resource availability. In conclusion, with regard to the further forest development, it could be assumed that the absence of disturbance events resulting in large openings leads to a reduction in the number of P. serotina, R. pseudoacacia, and Q. robur individuals during succession. Nevertheless, disturbances on wetter soils, e.g. related to the natural river dynamics, will clearly favour the seedling regeneration of Q. robur compared to the non-native species, which are generally limited to the drier sites of the floodplain forests.
P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height ... more P. serotina is a deciduous, single-stemmed tree, often medium- to large-sized, up 38 m in height and over 1.2 m or more in dbh in its native range in the eastern USA, though south-western varieties are much smaller. However, where introduced in Central Europe, P. serotina is mostly a shrub, only rarely a tree up to 20 m in height. Black cherry was among the first American trees to be cultivated as an ornamental in European gardens, introduced to England in 1629. In many places it has become naturalized and appears to be highly invasive. The invasive behaviour of this species in several northern and central European countries should be taken into account when considering future introductions to moist, temperate climates.
AimTo determine biotic and abiotic controls on pine invasion globally within six ecoregions that ... more AimTo determine biotic and abiotic controls on pine invasion globally within six ecoregions that include both introduced and native ranges.LocationsRío Negro province, Argentina; Aysén and Araucanía regions, Chile; South Island (two ecoregions), New Zealand; Greater Yellowstone ecosystem, USA.MethodsWe quantified tree abundance and size across invasion fronts of the widespread invasive tree species Pinus contorta at each of the nine sites, encompassing both the native and introduced range. We also determined the relative importance of propagule pressure, abiotic characteristics and biotic factors for invasion success. Finally, key plant population metrics such as individual tree growth rates and reproductive effort were compared between native and introduced ranges.ResultsPinus contorta density decreased with increasing distance from source population in all cases, but the importance and shape of this relationship differed among sites due, primarily to biotic factors. For example, a...
Plants are connected to habitats by functional traits which are filtered by environmental gradien... more Plants are connected to habitats by functional traits which are filtered by environmental gradients. Since tree species composition in the forest canopy can influence ecosystem processes by changing resource availability, litter accumulation, and soil nutrient content, we hypothesised that non-native invasive trees can establish new environmental filters on the understorey communities. In the hardwood floodplain forests in Northern Italy, the invasive trees Robinia pseudoacacia L. and Prunus serotina Ehrh. are the dominant canopy species. We used trait data assembled from databases and iterative RLQ analysis to identify a parsimonious set of functional traits responding to environmental variables (soil, light availability, disturbance, and stand structure) and the dominant native and invasive canopy species. Then, RLQ and fourth-corner analysis was conducted to investigate the joint structure between macro-environmental variables and species traits and functional groups were identified. The trait composition of the herb-layer was significantly related to the main environmental gradients and the presence of the invaders in the canopy showed significant relationships with several traits. In particular, the presence of P. serotina may mitigate or even erase the effect of disturbances, maintaining a stable forest microclimate and thus favouring ‘true’ forest species, while R. pseudoacacia may slow down forest succession and regeneration by establishing new stable associations with a graminoid-dominated understorey. The impact of the two invasive trees on herb layer composition appears to differ, indicating that different management and control strategies may be needed.
Species pool hypothesis is broadly known and frequently tested in various regions and vegetation ... more Species pool hypothesis is broadly known and frequently tested in various regions and vegetation types. However it has not been tested in the arid Xinjiang region of China due to lack of data. Here with systematic data from references and field survey, we comprehensively examined species pool hypothesis in this region. Took species richness in 0.1° × 0.1° grid cells as regional species richness (RSR) which were obtained from the distribution maps of vascular plant species, and took species diversity of 190 and 103 plots in forest and grassland biomes across Xinjiang as local species richness (LSR), together with the digitalized soil pH and climate data, we tested the species pool hypothesis in this region. We found that: (1) the average RSR was higher in mountains than that in basins and it was negatively correlated with soil pH in mountains while positively correlated with soil pH in basins in Xinjiang; (2) RSR showed a positive correlation with mean annual precipitation (MAP) whil...
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