Artemisia sieberishrubs have contrasting specific effects on understory species in Iranian steppes

Abstract

Questions (a) Are there contrasting short‐ and long‐term effects of shrubs on understorey species that may balance at the community level? (b) Are these effects due to the responses of different understorey species groups? (c) Are these effects contributing to community composition? Location An Artemisia steppe community in Golestan National Park (North‐East Iran). Methods We used both the removal and observational methods to separate short‐ from long‐term effects of Artemisia sieberi Besser on the cover of 18 subordinate species and the relative interaction index (RII) to calculate species’ responses. We conducted a principal components analysis (PCA) on species RII and grouped species with a cluster analysis depending on their responses to the shrubs. Another PCA on understorey composition plots was conducted to assess the consequences of shrub effects for community composition. Results Artemisia had negative short‐term and positive long‐term community‐level effects that balanced each other to produce neutral net effects. Short‐ and long‐term effects were due to the responses of different species groups, dominantly annuals and perennial grasses, respectively. Although balancing at the community level, the different shrub effects significantly contributed to explain community composition. Conclusions Our study highlights that a dominant foundation shrub may have contrasting short‐ and long‐term effects on different groups of understorey species that contribute to explain community composition, although balancing at the community level.

Plant–plant interactions determine natural restoration of plant biodiversity over time, in a degraded mined land

“…It seems that an increased taxonomic diversity in Artemisia patches and functional and phylogenetic diversity in Stipa patches are influenced by the presence of a wide range of plant species or by some specific plant species with different functional identities and distant evolutionary relatedness. However, some recent studies have shown negative or neutral effects of Artemisia patches on plant biodiversity structure, especially on taxonomic diversity (Bahalkeh et al, 2021 ; Rahmanian et al, 2021 ). These contrasting results are likely to be contingent on different environmental conditions.…”

Artemisia sieberi dominated landscapes of Northeastern Iran host great diversity in lichen and annual plant species

“…Thus, the combination of species-specific effects of Artemisia on neighbors may result in the differences in lichen and annual species composition found from site to site. Bahalkeh et al (2021) found contrasting effects of A. sieberi on neighbor plants, and Jankju (2013) found facilitative to neutral effects of A. kopetdaghensis depending on climatic conditions. These different interactions of Artemisia could be explained by several factors.…”

“…Percentage cover of the Artemisia shrub ranged on average from 17.6%±3.0 (Alagol) to 25.5%± 8.8 (Bagh valley). Almeh valley is alluvial and contain the upstream deposits of stones, pebbles, clay with slopes below 5%, but Bagh valley contain the upstream tiny sediments with slopes below 2% (Bahalkeh et al, 2021), Alikhani consists of a gentle hilly landscape. Alagol includes small loess hills around the Alagol wetlands (Kakeh et al, 2018).…”

“…Although the effect of Artemisia plants on understory species, development is debatable, some studies have demonstrated that the allelopathic effects of Artemisia may limit the successful establishment of understory species in laboratory and field conditions (Escudero et al, 2000;Jessing et al, 2014;Pueyo et al, 2016;Arroyo et al, 2017Arroyo et al, , 2018. However, Artemisia shrubs have been shown to have moderate nursing effects on perennial grasses in stressful conditions in Northeast Iran (Jankju, 2013;Bahalkeh et al, 2021), probably because Artemisia shrubs can mitigate unfavorable conditions by creating fertility islands and protecting plants from grazing (Callaway and Pugnaire, 1999;Ahmadian et al, 2018c;Ahmadian et al, 2019).Biological soil crusts (BSCs) are assemblages of organisms composed mainly of cyanobacteria, bryophytes, and lichens which are found throughout the world's drylands (Belnap and Lange, 2003). BSCs are critical drivers of ecosystem function, such as carbon, nitrogen, and water cycling, limiting soil evapotranspiration, and enhancing resource availability beneath them (Delgado-Baquerizo et al, 2013;Berdugo et al, 2014).…”

Species‐group responses improve our understanding of the effects of community dominants on subordinate species along a grazing gradient

“…For the Tibet Plateau, Michalet et al (2015) evidenced the occurrence of contrasting direct and indirect responses of forb species to the influence of dominant shrubs and grasses. However, because in their study the contrasting species-group level responses balanced each other, community-level responses in terms of forb biomass and richness were null or very weak (see also Wang et al, 2017Wang et al, , 2019Bahalkeh et al, 2021). Researchers argued that this should occur in species-rich communities from intermediate environmental conditions because these are known to include different functional strategies (Grime, 1973;Michalet et al, 2006).…”