Concepts of keystone species and species importance in ecology

This paper discussed the keystone species concept and introduced the typical characteristics of keystone species and their identification in communities or ecosystems. Based on the research of the keystone species, the concept of species importance (SI) was first advanced in this paper. The species importance can be simply understood as the important value of species in the ecosystem, which consists of three indexes: species structural important value (SIV), functional important value (FIV) and dynamical important value (DIV). With the indexes, the evaluation was also made on species importance of arbor trees in the Three-Hardwood forests (Fraxinus mandshurica, Juglans mandshurica, and Phellodendron amurense) ecosystem.

The Concept, Connotation and Significance of Cultural Keystone Species in Agricultural Heritage Systems

As a new type of heritage, Agricultural Heritage Systems(AHS), represented by Globally Important Agricultural Heritage Systems(GIAHS) designated by Food and Agriculture Organization of the United Nations(FAO)and Nationally Important Agricultural Heritage Systems(NIAHS) designated by some countries’ Ministry of Agriculture, are typical Social-Ecological Systems(SES), which usually are rich in biodiversity, traditional knowledge,resource utilization technology and outstanding cultural landscapes. Cultural Keystone Species(CKS) are defined as the culturally salient species that shape the cultural identity of a people in a major way. CKS can be used as a prominent tool for the synergistic conservation of SES biology and culture, and to promote the overall enhancement of system functions. This paper summarizes a review of the definition of the CKS and its application in SES conservation. According to the characteristics and protection needs of AHS, this paper defined the CKS in AHS as:“Composites of biological resources and cultural practices, which have a significant impact on the stability of local society and culture systems, contribute to the achievement of AHS’ conservation goals.” Based on this definition,we analyzed the significance of the identification of CKS in AHS. First of all, CKS help to quickly identify the key elements of AHS. Secondly, CKS can promote community participation in the conservation and development of AHS. In addition, the identification of CKS has a significant role in food and livelihood security, biodiversity conservation, traditional knowledge and technology transmission, social organization maintenance, and cultural landscape maintenance in AHS, which helps to achieve the conservation goals of GIAHS and/or NIAHS.

Salinity-oriented environmental flows for keystone species in the Modaomen Estuary, China

Rapid development and urbanization in recent years have contributed to a reduction in freshwater discharge and intensified saltwater intrusion in the Pearl River Delta. This comprises a significant threat to potable water supplies and overall estuary ecosystem health. In this study, the environmental flows of the Modaomen Estuary, one of the estuaries of the Pear/River Delta in China, were determined based on the salinity demand of keystone species and the linear relationship between river discharge and estuarine salinity. The estimated minimum and optimal annual environmental flows in the Modaomen Estuary were 116.8 ~ I09m3 and 273.8 ~ 109m3, respectively, representing 59.3% and 139.0% of the natural runoff. Water quality assessments in recent years indicate that the environmental flows have not been satisfied most of the time, particularly the optimal environmental flow, despite implementation of various water regulations since 2005. Therefore, water regulations and wetland network recov- eries based on rational environmental flows should be implemented to alleviate saltwater intrusion and for the creation of an ideal estuarine habitat.

Aviary measurements of dominance and affiliation between members of mixed-species birds flocks in southern China

In mutualistic interactions,all parties are usually considered to benefit;yet there may be asymmetries in mutualisms where some partners/individuals benefit more than others.Such is thought to be the case in mixedspecies flocks of birds,where following species are thought to benefit more than leading species,and leading species may not be able to escape the association if they are subordinate to other species.We measured dominance and affiliation patterns of a mixed-species flock system of southern China in an aviary where these variables could be measured in a standardized way.In eight wild-caught flocks,the leading species,David’s Fulvetta(Alcippe davidi),was usually among the more subordinate flock members(ranking 9 of 13 species,with the the most dominant species ranked number one,and dominance measured by normalized David’s scores).Dominance was strongly influenced by body mass,and not by bill length or the number of individuals.Female fulvettas in particular tended to be among the most subordinate individuals in the flock.There was evidence of a negative relationship between a species pair’s affiliation,measured as the percentage of all observations in which these two species were found perching together,and their difference in ranking in the dominance hierarchy,particularly when some ground species,which are not likely to remain in flocks long term,were removed from the analysis.Species pairs that had more pronounced differences in their dominance rankings were less likely to be affiliated,which is consistent with the idea that subordinate species may avoid dominants.David’s Fulvetta is a strong information provider,so other species are likely benefitted in this relationship.Our data suggest one reason that fulvettas stay in flocks is that they may be subordinate and therefore have little control over who associates with them.

The composition of mixed-species flocks of birds in and around Chitwan National Park,Nepal

Background:Mixed-species flocks(MSFs)have been well sampled in the South Asia,but there has been as yet surprisingly little work on MSFs of Nepal,despite a diverse and well-studied avifauna.We surveyed MSFs in two forest types in and around the Important Bird Area of Chitwan National Park in Nepal,between 150 and 800 m a.s.l.,to provide a first description of the composition of MSFs in this area.We also aimed to understand which species should be considered‘nuclear species',important to forming MSFs or leading them forward.Results:In total,we collected records on 222 MSFs that included 100 species,and 6097 individuals.The MSFs were similar to worldwide patterns in being dominated by leaf-gleaning,non-terrestrial insectivores.However,the MSFs were more dominated by canopy species than usual,and did not have a clear gregarious,understory leading species.Rather drongos(Family Dicruridae)and minivets(Family Campephagidae,Genus Pericrocotus)acted as leaders,and a cluster analysis of composition showed one group of large body size MSFs particularly characterized by the presence of the Greater Racket-tailed Drongo(Dicrurus paradiseus).Conclusions:Drongos are known to provide both costs and benefits to other flock participants:they are aggressive birds that can steal food,and manipulate other species with their vocalizations,but at the same time they are‘sentinel species'that produce information about predation risk other species can use.This study demonstrates that drongos can be considered nuclear species for some types of MSFs,despite the potential costs of their presence.MSFs led by sentinel species thus may form in Asia,as well as in the Neotropics.

Interaction network between frugivorous birds and zoochorous plants in cloud forest riparian strips immersed in anthropic landscapes

Worldwide,tropical montane cloud forest is one of the most important and biodiverse ecosystems;however,it is also one of those most threatened by anthropic activities.These activities lead to a fragmented,deforested landscape with narrow riparian forest strips immersed in an agricultural matrix dominated by pastures.Here,we characterize the interaction network between frugivorous birds and zoochorous plants in riparian strips of cloud forest in deforested landscapes of Central Veracruz,Mexico.To characterize the network of this mutualistic interaction,we estimated network-and species-level metrics using the Bipartite R package.Nestedness,modularity and robustness were used to describe network structure.Centrality measures of degree,closeness,betweenness centrality and their relative contribution to nestedness were used to determine the importance of each bird/plant species to the network’s structure.This interaction network has 24 species of birds and 30 species of plants,with low connectance(0.11),low nestedness(11.53),and intermediate but not significant modularity(0.49).The bird species most important to network stability were Chlorospingus flavopectus,Myadestes occidentalis,and Catharus mexicanus.The most important plants were Conostegia xalapensis,C.arborea,and Rubus ulmifolius.Network robustness varied from 0.36 to 0.86 and its stability is compromised when species of birds or plants with the highest values of centrality are removed,with plant removal more detrimental.Riparian strips of cloud forest crossing deforested areas maintain a relatively rich set of birds that disperse the seeds of many forest plants,thus they are crucial to the preservation of this mutualistic network in anthropic landscapes.Network stability is severely undermined by the loss of any of the few species—whether birds or plants—with high centrality values.The most important plants for this stability are pioneer tree and shrub species that provide food for several bird species,and they are also crucial to cloud forest regeneration.A worrisome finding is that some of the bird species most important to network stability are also among the most sought-after as ornamental birds by illegal collectors in the region.

Functional-trait ecology of the plateau pika Ochotona curzoniae in the Qinghai-Tibetan Plateau ecosystem

Understanding a species’functional traits allows for a directed and productive perspective on the role a species plays in nature,and thus its relative importance to conservation planning.The functionaltrait ecology of the plateau pika Ochotona curzoniae is examined to better understand the resilience and sustainability of the high alpine grasslands of the Qinghai-Tibetan Plateau(QTP).The key functional traits of plateau pikas are their abundance and behavior of digging extensive burrow systems.Plateau pikas have been poisoned over a significant part of their original geographic distribution across the QTP,allowing comparison of ecological communities with and without pikas.Nearly all mammalian and avian carnivores,most of which are obligate predators on pikas,have been lost in regions where pikas have been poisoned.Most endemic birds on the QTP nest in pika burrows;when pikas are poisoned,burrows collapse,and these birds are greatly reduced in number.Due to the biopedturbation resulting from their burrows,regional plant species richness is higher in areas with pikas than without.The presence of pika burrows allows higher rates of infiltration during heavy monsoon rains compared to poisoned areas,possibly mitigating runoff and the potential for serious downslope erosion and flooding.Thus,the functional traits of plateau pikas enhance native biodiversity and other important ecosystem functions;these traits are irreplaceable.As plateau pikas are not natural colonizers,active reintroduction programs are needed to restore pikas to areas from which they have been poisoned to restore the important functional ecological traits of pikas.

Rodent burrow network dynamics under human-induced landscape transformation from desert to steppe in Kalmykian rangelands

Rodents play an important role in rangelands through the engineering of extensive burrow systems,which pro­vides key habitats for many animal and plant species.We have analyzed the long-term variation in the abun­dance and distribution of rodent burrows in grazing ecosystems of southern Russia(Kalmykia)under the land­scape change from desert to steppe caused by the drastic reduction of livestock after the collapse of the USSR in the early 1990s.We conducted burrow surveys in the“desert”(1980)and“steppe”(2017)periods on 193-km transects.We found considerable changes in burrow abundance and distribution,as well as evidence of desert habitat fragmentation and isolation caused by the expansion of tall-grass communities.Burrows of the open-dwelling diurnal ground squirrel(Spermophilus pygmaeus),the dominant and the keystone species during the“desert”period,almost completely disappeared from the rodent burrow network by 2017,indicating signifi­cant habitat loss.In contrast,the burrows of the folivorous social vole(Microtus socialis)which was rare in the 1980s,became abundant and ubiquitously distributed.The burrow density of the desert-dwelling psammophi­lous midday gerbil(Meriones meridianus)decreased,while the distances between occupied patches increased,indicating desert habitat fragmentation and loss of population connectivity.Burrows of the folivorous tamarisk gerbils(M.tamariscinus)were recorded only sporadically in both 1980 and 2017.The observed changes in the rodent burrow network,the key component of grazing ecosystems,correlate with rodent species ecology and can have long-term and important consequences for ecosystem functioning.