Interspecific association of sika deer in terrestrial animal communities of Liancheng National Nature Reserve, China

The prevention and control of invasive of alien species is an important work for nature reserves.This study analyzes the development trend of the alien species sika deer in Liancheng National Nature Reserve.From October 2019 to June 2020,3523 valid photos and videos of terrestrial animals were acquired from 130 camera traps,and sika deer were recorded in 21 photos from 13 traps.The survival of the sika deer population was investigated by means of morphological identification,population structure analysis,species relative abundance indices,and species spatial association analysis.A total of 13 sika deer individuals were identified by camera trapping,including two kids and three subadults representing the reproductive capacity of the population.Spatially,sika deer is not associated with any local species and was outside the spatial association network of terrestrial animals in Liancheng National Nature Reserve,indicating that the sika deer population has not been integrated into the local community and has failed to perform its ecological function.It is worth noting that the reserve provides habitat suitable for sika deer and that the population has adequate reproductive capacity.Due to the lack of large apex predators in the reserve,the population size of ungulates such as sika deer,red deer,and Siberian roe deer may expand and lead to population outbreaks and the associated problems for the ecosystem.To restore large-and medium-sized carnivores and avoid the population outbreak of the species,the present challenges require immediate attention in Liancheng National Nature Reserve.

Multiple Spatial Scale Analysis of the Niche Characteristics of the Rhododendron dauricum Plant Communities in Northeast China

This study aims to verify the concept of niches at multiple spatial scales in plant communities.To this end,we analyzed the niche characteristic of Rhododendron dauricum plant communities in Northeast China at three spatial scales.At the local scale,we calculated the Importance Value(IV)of species in five communities in the north of the Da Hinggan Mountains.At the intermediate scale,we examined five communities in their entirety,calculated the niche breadth of the species,and integrated niche overlap and interspecific association to analyze interspecific relationships.Further,the generalized additive model(GAM)was used to analyze the impact of topography and soil factors on niche characteristics.At the regional scale,we analyzed the geographical distribution of dominant species of R.dauricum plant communities in Northeast China and used principal component analysis(PCA)to analyze the impact of geographical and climate factors on species distribution.The results show that at the local scale,the IV of the species in each community varies widely.At the intermediate scale,species with a wide niche breadth tend to have a high value for IV.Larix gmelinii,Betula platyphylla,R.dauricum,Ledum palustre,and Vaccinium vitis-idaea had a relatively wide niche breadth and a high niche overlap,and the interspecific associations were almost all positive.Elevation and soil nutrients were the most dominant environmental factors.At the regional scale,species with a wide niche breadth tend to have a wide range of distribution,and temperature and precipitation were the most dominant environmental factors.This study suggests that the niche characteristics at three scales are both related and different.Niche characteristics at the local scale were various and labile,and niche characteristics at the intermediate and regional scales were relatively regular.These results show some degree of consistency with previous studies from an evolutionary perspective.The action mechanisms of these communities are related to differences in the dominant environmental factors.In addition,the integration of niche overlap and interspecific association determine interspecific relationships more accurately.

Species diversity and interspecific association in development sequence of Hippophae rhamnoides plantations in the Loess Hilly Region, China

Based on our field investigation,we analyzed the characteristics of species diversity and interspecific association at different development stages of Hippohae rhamnoides plantations.The results show that the species diversities of the shrub layer,grass layer and the whole community of the H.rhamnoides plantations all fluctuated in an“S”shape pattern.At different development stages,the species richness and diversity were higher in the grass layer than in the shrub layer.The shrub species diversity was lower on bare land,but increased gradually with development of the community.The shrub evenness index was higher in 13-year forest stand,while the grass diversity index was higher in the 3-year and 25-year plantations and lower in the 8-year plantation.The positive and negative absolute values of interspecific association between H.rhamonides and other principal species changed in a parabolic pattern.The significance level and intensity of interspecific association were lower or weaker in the13-year plantation,indicating that the species substitution rate slowed down,competition became less intense and community composition and its structure reached a relatively stable state.Therefore,to improve the ecological environment,priority should be given to the protection of the H.rhamnoides plantations younger than 13 years,while for those of 25 year plantations,moderate thinning should be made to promote their regeneration.

Species composition and correlation of understory woody plants in Chinese fir plantation in the lower subtropical area

There are 71 species in the shrub layer of the Cunninghamia lanceolata plantation after natural succession.The species richness and diversity have increased with slight anthropogenic disturbance.The status and function of understory woody species were judged by the analysis of the important value(IV).χ2 statistics and r test were used for testing the significance of interspecific association and correlation among 25 main understory woody plants selected from the woody population.The results clearly showed their interspecific relationships and their differences in resource utilization.Species-pairs of positive association were in the majority.Most species were accommodated in the shady habitat.There was a positive correlation between the IV of the species and the interspecific association.The higher the IV of the species,the closer and more significant was the interspecific association.Based on analytical results of interspecific association and correlation,25 woody plants in the shrub layer could be divided into four ecological species groups:I.Ficus hispida+Antidesma bunius+Mallotus barbatus+Ficus cunia+Saurauia tristyla+Mallotus philippinensis+Maesa japonica+Ficus hirta+Alchornea rugosa+Ficus fulva+Mallotus apelta;II.Cudrania tricuspidata+Schefflera octophylla;III.Cunninghamia lanceolata+Clerodendron cytophyllum+Millettia semicastrata+Randia spinosa+Litsea cubeba+Litsea pungens;IV.Ardisia japonica+Psychotria rubra+Vitex quinata+Cephalanthus occidentalis+Pithecellobium lucidum+Mycetia sinensis.If species group III or II is the advantaged species in the shrub layer,the community would change from a coniferous forest to a sparse evergreen broad-leaved forest.For group IV,the community would be relatively stable.For group I,the coniferous forest would be mixed with coniferous-broad leaved forest.The classification of ecological species groups would provide a theoretical basis on judging its ecological function,adjusting the stand structure of the plantation and directing the suitable natural vegetation type through the close-natural restoration process.

An uneasy alliance:a nesting association between aggressive ants and equally fierce social wasps

Although the Neotropical territorially dominant arboreal ant Azteca chartifex Forel is very aggressive towards any intruder,its populous colonies tolerate the close presence of the fierce polistine wasp Polybia rejecta(F.).In French Guiana,83.33%of the 48 P.rejecta nests recorded were found side by side with those of A.chartifex.This nesting association results in mutual protection from predators(i.e.,the wasps protected from army ants;the ants protected from birds).We conducted field studies,laboratorybased behavioral experiments and chemical analyses to elucidate the mechanisms allowing the persistence of this association.Due to differences in the cuticular profiles of the two species,we eliminated the possibility of chemical mimicry.Also,analyses of the carton nests did not reveal traces of marking on the envelopes.Because ant forager flows were not perturbed by extracts from the wasps’Dufour’s and venom glands,we rejected any hypothetical action of repulsive chemicals.Nevertheless,we noted that the wasps"scraped"the surface of the upper part of their nest envelope using their mandibles,likely removing the ants'scent trails,and an experiment showed that ant foragers were perturbed by the removal of their scent trails.This leads us to use the term"erasure hypothesis."Thus,this nesting association persists thanks to a relative tolerance by the ants towards wasp presence and the behavior of the wasps that allows them to"contain"their associated ants through the elimination of their scent trails,direct attacks,"wing-buzzing"behavior and ejecting the ants.