Effects of drought and slope aspect on canopy facilitation in a mountainous rangeland

Farzam, Mohammad; Ejtehadi, Hamid

doi:10.1093/jpe/rtw070

Cited by 17 publications

(22 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results are in contrast, however, to the common finding that drought reduces the species richness in various grasslands (Copeland et al., ; Farzam & Ejtehadi, ; Liu, Estiarte, Ogaya, Yang, & Peñuelas, ). These differences may involve competitive mechanisms, with the competitive interaction between overstorey and grass increased under stress (Scholes & Archer, ; Weltzin & McPherson, ).…”

Section: Discussioncontrasting

confidence: 99%

Precipitation reduction alters herbaceous community structure and composition in a savanna

Jin

Liu

et al. 2019

J Vegetation Science

View full text Add to dashboard Cite

Questions In the changing climate scenario, the decline in precipitation is expected to alter water availability for plants, which in turn affects plant community structure and composition. The responses of community composition and structure to declines in precipitation are well documented in other biomes but remain understudied in water‐limited savannas. Location A savanna ecosystem in southwest China. Methods We used a four‐year (2014–2017) precipitation manipulation experiment to examine changes in herbaceous community composition and structure across the species, functional group and community levels under precipitation reduction. Results Precipitation reduction significantly decreased the average height and percentage cover of the herbaceous community, while increasing species richness and the Pielou evenness index. Precipitation reduction significantly decreased average height, percentage cover and relative abundance of graminoids and perennials, but increased those of forbs and annuals. Precipitation reduction prompted a shift in the dominant species of the herbaceous community towards Fimbristylis monostachya. Conclusions The results show that precipitation reduction changed the composition and structure of the herbaceous community of this savanna. Furthermore, they provide strong evidence that changes in herbaceous community structure and composition in response to the intensity and duration of precipitation reduction in this savanna exhibited relatively low thresholds, which suggests that the herbaceous community's response to a decline in precipitation was essentially nonlinear. These findings imply that even relatively small declines in precipitation may stimulate shifts in plant community structure and composition and affect the function and stability of savanna ecosystems.

show abstract

Section: Discussioncontrasting

confidence: 99%

Precipitation reduction alters herbaceous community structure and composition in a savanna

Jin

Liu

et al. 2019

J Vegetation Science

View full text Add to dashboard Cite

show abstract

“…Thus, at the mountain belt of the continental semi‐arid climate of northeast Iran, we sampled understorey species composition and cover at two positions, within the canopy of the cushion shrub Onobrychis cornuta and in the open, at both wet north and dry south exposures and in burned and unburned conditions. Although studies assessing the diversity and species composition of cushion‐dominated communities in Iran have been made (Kürschner, 1986; Akhani, 1998; Noroozi et al, 2008; Memariani et al, 2016; Farzam & Ejtehadi, 2017), none of them have assessed variation in effects of cushion shrubs on understorey species along gradients of stress and disturbance. However, Al Hayek et al, (2015a) and Michalet et al, (2017) have shown that two phenotypes of Onobrychis cornuta with contrasting competitive and facilitative abilities occur in different microhabitats of the subalpine belt of the mediterranean climate of Mount Lebanon (Lebanon).…”

Section: Introductionmentioning

confidence: 99%

Fire slightly decreases the competitive effects of a thorny cushion shrub in a semi‐arid mountain steppe in the short term

Bahalkeh

Abedi

Tilaki

et al. 2021

Applied Vegetation Science

View full text Add to dashboard Cite

Questions Studies in alpine environments have highlighted dominant facilitative effects of cushion species for diversity. Many fewer studies have assessed the effects of cushion shrubs in drier and less cold mountain habitats and how these effects vary within the shrub canopy and with increasing drought stress with exposure and disturbance by fire. Location A mountain steppe of the Golestan National Park in the semi‐arid climate of northeast Iran. Methods We quantified the cover of understorey species at the center and edge of the canopy of the thorny cushion shrub Onobrychis cornuta and in paired open areas, in north and south exposures and unburned and burned plots, two years after a fire. Soil chemical variables and moisture were measured in treatments. We quantified cushions’ center and edge effects on understorey species cover with the Relative Interaction Index (RII). Treatment effects on RII cover were analyzed with generalized linear mixed‐effects models (GLMM) and species composition with Correspondence Analysis. Results In unburned plots, competition for cover was very high at cushion centers and strongly decreased at cushion edges. Exposure stress did not affect competition in unburned plots. Fire slightly decreased competition but only at center cushion shrub position and at south exposure. Species composition was mostly affected by exposure and fire treatments, although there was subtle variation in species composition among patches due to fire. Cushion position, fire and exposure treatments affected soil moisture and chemical variables, but soil changes did not explain cushion effects on understorey cover and their variations along treatments. Conclusions The effects of the cushion shrub were highly negative and in particular at cushion center, likely due to interference and competition for light in a dry and not too cold environment. Fire only slightly decreased competition in the short term, likely due to the delayed response of understorey species to disturbance induced by fire.

show abstract

“…As nurses modify microhabitat temperature (Breshears et al 1998, Drezner 2006, Cavieres et al 2007), moisture (Maher et al 2005, Cavieres et al 2007) and nutrients (Pugnaire et al 1996, Zabinski et al 2002, Gómez‐Aparicio et al 2005), most studies have focused on comparing the species richness beneath the canopy of nurses versus that of adjacent open sites. Studies using this approach have found that species richness beneath nurses is higher (Raffaele and Veblen 1998, Badano et al 2005, Koorem and Moora 2010), similar or lower (Gutiérrez et al 1993, Pugnaire et al 1996, Madrigal‐González et al 2016) or results dependent on species‐specific relationships (Soliveres et al 2012a, Pistón et al 2016, Farzam and Ejtehadi 2017). However, as both microhabitats (within or beneath nurse and open areas) belong to the same community, it is important to evaluate whether there are species added to the community due to the presence of nurses (Cavieres and Badano 2009, Cavieres et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Plant–plant facilitation increases with reduced phylogenetic relatedness along an elevation gradient

Duarte

Verdú

Cavieres

et al. 2020

Oikos

View full text Add to dashboard Cite

Environmental conditions can modify the intensity and sign of ecological interactions. The stress gradient hypothesis (SGH) predicts that facilitation becomes more important than competition under stressful conditions. To properly test this hypothesis, it is necessary to account for all (not a subset of) interactions occurring in the communities and consider that species do not interact at random but following a specific pattern. We aim to assess elevational changes in facilitation, in terms of species richness, frequency and intensity of the interaction as a function of the evolutionary relatedness between nurses and their associated species. We sampled nurse and their facilitated plant species in two 1000–2000 m. elevation gradients in Mediterranean Chile where low temperature imposes a mortality filter on seedlings. We first estimated the relative importance of facilitation as a mechanism adding new species to communities distributed along these gradients. We then tested whether the frequency and intensity of facilitation increases with elevation, taking into account the evolutionary relatedness of the nurse species and the facilitated species. We found that nurses increase the species richness of the community by up to 35%. Facilitative interactions are more frequent than competitive interactions (56% versus 44%) and facilitation intensity increased with elevation for interactions involving distantly related lineages. Our results highlight the importance of including an evolutionary dimension in the study of facilitation to have a clearer picture of the mechanisms enabling species to coexist and survive under stressful conditions. This knowledge is especially relevant to conserve vulnerable and threatened communities facing new climate scenarios, such as those located in Mediterranean‐type ecosystems.

show abstract

Effects of drought and slope aspect on canopy facilitation in a mountainous rangeland

Cited by 17 publications

References 37 publications

Precipitation reduction alters herbaceous community structure and composition in a savanna

Precipitation reduction alters herbaceous community structure and composition in a savanna

Fire slightly decreases the competitive effects of a thorny cushion shrub in a semi‐arid mountain steppe in the short term

Plant–plant facilitation increases with reduced phylogenetic relatedness along an elevation gradient

Contact Info

Product

Resources

About