scholarly journals The dark side of facilitation: native shrubs facilitate exotic annuals more strongly than native annuals

NeoBiota ◽  
2019 ◽  
Vol 44 ◽  
pp. 75-93 ◽  
Author(s):  
Jacob E. Lucero ◽  
Taylor Noble ◽  
Stephanie Haas ◽  
Michael Westphal ◽  
H. Scott Butterfield ◽  
...  
Keyword(s):  
Biological Invasions ◽  
Exotic Species ◽  
Plant Community ◽  
Ecosystem Function ◽  
Foundation Species ◽  
Desert Ecosystem ◽  
Dark Side ◽  
Positive Interactions ◽  
Annual Plant ◽  
Exotic Invaders

Positive interactions enhance biodiversity and ecosystem function, but can also exacerbate biological invasions. Facilitation of exotic invaders by exotic foundation species (invasional meltdown) has been studied extensively, but facilitation of exotic invaders by native foundation species has attracted less attention. Specifically, very few studies have examined the extent that native foundation species facilitate native and exotic competitors. Understanding the processes that mediate interactions between native and exotic species can help explain, predict, and improve management of biological invasions. Here, we examined the effects of native foundation shrubs on the relative abundance of the annual plant community – including native and exotic taxa – from 2015–2018 in a desert ecosystem at Carrizo Plain National Monument, California, USA (elevation: 723 m). Shrub effects varied by year and by the identity of annual species, but shrubs consistently enhanced the abundance of the annual plant community and facilitated both native (n=17 species) and exotic (n=4 species) taxa. However, at the provenance level, exotic annuals were facilitated 2.75 times stronger in abundance than native annuals, and exotic annuals were always more abundant than natives both near and away from shrubs. Our study reaffirms facilitation as an important process in the organisation of plant communities and confirms that both native and exotic species can form positive associations with native foundation species. However, facilitation by native foundation species can exacerbate biological invasions by increasing the local abundance of exotic invaders. Thus, the force of facilitation can have a dark side relevant to ecosystem function and management.

scholarly journals Foundation species loss affects vegetation structure more than ecosystem function in a northeastern USA forest

PeerJ ◽  
2013 ◽  
Vol 1 ◽  
pp. e41 ◽  
Author(s):  
David A. Orwig ◽  
Audrey A. Barker Plotkin ◽  
Eric A. Davidson ◽  
Heidi Lux ◽  
Kathleen E. Savage ◽  
...  
Keyword(s):  
Ecosystem Function ◽  
Vegetation Structure ◽  
Foundation Species ◽  
Species Loss ◽  
Northeastern Usa

scholarly journals Acquisition of fungi from the environment modifies ambrosia beetle mycobiome during invasion

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8103 ◽  
Author(s):  
Davide Rassati ◽  
Lorenzo Marini ◽  
Antonino Malacrinò
Keyword(s):  
Biological Invasions ◽  
Exotic Species ◽  
Ecological Factors ◽  
Ambrosia Beetle ◽  
Fungal Communities ◽  
Bottleneck Effect ◽  
Factors Affecting ◽  
Microbial Symbionts ◽  
Insect Fungi ◽  
Native Fungi

Microbial symbionts can play critical roles when their host attempts to colonize a new habitat. The lack of symbiont adaptation can in fact hinder the invasion process of their host. This scenario could change if the exotic species are able to acquire microorganisms from the invaded environment. Understanding the ecological factors that influence the take-up of new microorganisms is thus essential to clarify the mechanisms behind biological invasions. In this study, we tested whether different forest habitats influence the structure of the fungal communities associated with ambrosia beetles. We collected individuals of the most widespread exotic (Xylosandrus germanus) and native (Xyleborinus saxesenii) ambrosia beetle species in Europe in several old-growth and restored forests. We characterized the fungal communities associated with both species via metabarcoding. We showed that forest habitat shaped the community of fungi associated with both species, but the effect was stronger for the exotic X. germanus. Our results support the hypothesis that the direct contact with the mycobiome of the invaded environment might lead an exotic species to acquire native fungi. This process is likely favored by the occurrence of a bottleneck effect at the mycobiome level and/or the disruption of the mechanisms sustaining co-evolved insect-fungi symbiosis. Our study contributes to the understanding of the factors affecting insect-microbes interactions, helping to clarify the mechanisms behind biological invasions.

scholarly journals Regional climate and local-scale biotic acceptance explain native–exotic richness relationships in Australian annual plant communities

2018 ◽  
Vol 285 (1886) ◽  
pp. 20181328 ◽  
Author(s):  
Isaac. R. Towers ◽  
John. M. Dwyer
Keyword(s):  
Exotic Species ◽  
Structural Equation ◽  
Spatial Scales ◽  
Regional Climate ◽  
Soil Surface ◽  
Equation Model ◽  
Annual Plant ◽  
Regional Temperature ◽  
Neighbourhood Scale ◽  
Biotic Acceptance

Native and exotic species richness is expected to be negatively related at small spatial scales where individuals interact, and positive at larger spatial scales as a greater variety of habitats are sampled. However, a range of native–exotic richness relationships (NERRs) have been reported, including positive at small scales and negative at larger scales. We present a hierarchical metacommunity framework to explain how contrasting NERRs may emerge across scales and study systems, and then apply this framework to NERRs in an invaded winter annual plant system in southwest Western Australia. We analysed NERRs at increasing spatial scales from neighbourhoods (0.09 m 2 ) to communities (225 m 2 ) to metacommunities (greater than 10 ha) within a multilevel structural equation model. In contrast to many previous studies, native and exotic richness were positively related at the neighbourhood scale and were not significantly associated at larger scales. Heterogeneity in soil surface properties was weakly, but positively, associated with native and exotic richness at the community scale. Metacommunity exotic richness increased strongly with regional temperature and moisture availability, but relationships for native richness were negative and much weaker. Thus, we show that neutral NERRs can emerge at larger scales owing to differential climatic filtering of native and exotic species pools.

Nurse plants promote taxonomic and functional diversity in an arid Mediterranean annual plant community

2020 ◽  
Vol 31 (4) ◽  
pp. 658-666 ◽  
Author(s):  
Jaime Madrigal‐González ◽  
Carlos Cano‐Barbacil ◽  
Jaime Kigel ◽  
Pablo Ferrandis ◽  
Arantzazu L. Luzuriaga
Keyword(s):  
Plant Community ◽  
Functional Diversity ◽  
Annual Plant ◽  
Nurse Plants

The upland hardwood component of Prince Edward Island's remnant Acadian forest: determination of depth of edge and patterns of exotic plant invasion

2003 ◽  
Vol 81 (11) ◽  
pp. 1113-1128 ◽  
Author(s):  
Kate MacQuarrie ◽  
Christian Lacroix
Keyword(s):  
Exotic Species ◽  
Plant Community ◽  
Plant Invasion ◽  
Vascular Plants ◽  
Canopy Cover ◽  
Percent Cover ◽  
Exotic Plant ◽  
Exotic Plant Invasion ◽  
Acadian Forest ◽  
Study Sites

The upland hardwood component of Prince Edward Island's Acadian forest is among the best remaining examples of the precolonial landscape, but it has been severely fragmented during the past 300 years of human use and settlement. Despite the ecological importance of this remnant habitat and its level of fragmentation, there has been no assessment of depth of edge or exotic plant invasion in these areas. Three 300 m long edge–interior transects were established in each of six study sites. Nine 100-m2 circular plots were sampled along each transect at distances from 5.7 to 300 m; one external plot was established at each transect to sample species in adjacent habitats. In each plot, all vascular plants were identified, a visual estimate of percent cover was made, and soil temperature, canopy cover, and tree diameters were measured. An edge–interior plant community gradient was found within these forests; a plant community characteristic of interior conditions was not reached until a distance of more than 120 m from an edge. This suggests that upland hardwood protected areas smaller than 240 m on a side (5.75 ha) are unlikely to include interior habitat, and sites should be greater than 320 m on all sides (10.24 ha) to ensure at least some interior habitat for vascular plants. Invasion by exotic species was found to be more extensive than that reported from other jurisdictions, and innermost (300 m) plots were not free from exotics. Fifteen exotic species were found within the study sites, with Veronica officinalis (common speedwell) and Hieracium lachenalii (hawkweed) being the most invasive, both in terms of distance penetrated and area covered.Key words: Acadian forest, fragmentation, depth of edge, protected area, Veronica, Hieracium.

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