ID45: Native and non-native species range expansions in mountains

Abstract ID 633 | Date: 2022-09-13 13:30 – 13:42 | Type: Oral Presentation | Place: SOWI – Aula |

Berthelsen, Susanne (1); Töpper, Joachim Paul (1,2); Gya, Ragnhild (1,3); Vandvik, Vigdis (1,3)

A long-standing quest in ecology, with ever-increasing relevance in the face of climate change, is to understand the effects of climate on sexual reproduction and the dynamics of natural populations. Genetic variation enables species to adapt to new environments. Hence, sexual reproduction and the genetic variation it introduces into a population, may be vital for the plants’ ability to persist under a changing climate.

According to climate projections, western Norway will be experiencing higher temperatures and more precipitation in the future. A warmer and wetter climate will lead to increased productivity for the vegetation, hence enabling species adapted to a warmer climate to spread up in the mountains. Range-expanding species could have dramatic impacts on alpine plant communities and populations, particularly if they introduce novel features into their newly attained neighborhood. Studying how warming and range-expanding species affect flowering performance is therefore important to understand potential impacts of climate change on plant population persistence and range dynamics.

To test this, we have established a field experiment along a natural precipitation gradient in the mountains of western Norway. In this climate change field experiment we manipulate both temperature and competitive conditions in alpine vegetation, by using open-top chambers and through transplant experiments respectively. To simulate novel species colonizing upland plant communities, we transplanted lowland species with functional traits that are novel to the alpine vegetation into our alpine study sites. This creates interactions between species that have not co-occurred previously, and allows us to investigate the indirect colonization effects of climate on flower production.

Our study shows that alpine plants produce more flowers when they interact with lowland species with novel traits. Warming effects were significantly different between alpine forbs and graminoids. Forbs had a marginally significant decrease in flower production, but we found no apparent effects of warming on flower production in graminoids. Our findings suggest that competitive lowland species may obscure or counteract the warming-effects on flower production, and that sexual reproduction is a priority for alpine plants under increasing pressures from range-expanding species.

Abstract ID 685 | Date: 2022-09-13 13:42 – 13:54 | Type: Oral Presentation | Place: SOWI – Aula |

Larson, Christian (1); Chichinsky, Daniel (1); Maggio, Melissa (2); Rew, Lisa (1); Seipel, Tim (1)

Cirsium arvense is a perennial plant species with a broad environmental tolerance and is often distributed from low elevations to high elevations. It is native to south-eastern Europe but is a cosmopolitan weed throughout global temperate ecosystems, especially Europe and North America. Cirsium arvense is a weed that causes crop yield loss, reduces forage quality, and, in its non-native range, is associated with a reduction of native plant abundance and decreased biodiversity. Management of C. arvense is difficult because of its deep root rhizomes and substantial seed production, and usually includes mechanical disturbance or herbicides. The obligate C. arvense fungal pathogen (Puccinia punctiformis) can affect C. arvense performance and has potential to be used as a management tool. The aim of our study was to assess the occurrence and potential impact of P. punctiformis on C. arvense across an elevation gradient. Using C. arvense records from multiple land management agencies between 2017 and 2022, spanning across the Pacific Northwest USA, we evaluated populations demographics across its range. The records estimated patch size, percent cover of C. arvense, cover of plant functional groups, bare ground, and litter. In 2021, we expanded the project to include the total number of C. arvense ramets demonstrating symptoms of P. punctiformis infection in each patch, as well as the number of symptomatic C. arvense ramets in 1 m2 frames within each patch. We found that that as elevation increased C. arvense patch size decreased, its cover decreased, while its density increased. In addition, we found that P. punctiformis probability of occurrence increased as C. arvense density increased and, subsequently, the density of symptomatic C. arvense ramets and the probability of occurrence of P. punctiformis increased with elevation gain. To further evaluate the effects of P. punctiformis on C. arvense’s population expansion and individual performance across the environmental gradient, C. arvense populations were inoculated with the pathogen beginning in 2017. Starting in 2022, the effects of these inoculations will be assessed by evaluating patch size, fungal disease severity (presence/absence of infection and density of P. punctiformis infected ramets), and any associated changes in C. arvense cover or density.

Abstract ID 229 | Date: 2022-09-13 13:54 – 14:06 | Type: Oral Presentation | Place: SOWI – Aula |

Gwate, Onalenna (1); Canavan, Kim (2); Martin, Grant (1,2,3); Richardson, David M. (4); Clark, Vincent R. (1)

The range of plant species change in response to environmental conditions such as climate. Mountain socio-ecological systems are particularly vulnerable to climate change. Hence, it is important to have insights into species that could be ‘winners’ or ‘losers’ in a context of climate change. In this regard, the study sought to evaluate current and future habitat suitability of woody (Acacia dealbata, Leucosidea sericea, Venonanthura phospherica and grass (Poa annua) species in African mountains under present conditions, atmospheric CO₂ representative concentration pathways (RCPs) 4.5 (intermediate) and 8.5 (maximum concentration) climate scenarios. We applied the machine learning Maximum Entropy (MaxEnt) ensemble modelling to understand present and future habitat suitability of the selected species. We found that temperature will decline in African mountains under climate change, although climate change models suggest an increasing trajectory in future temperatures. This suggests that climate change models may not be capturing dynamics in the climate of African mountains, possibly due to a paucity of observed climate data when calibrating climate change models and as such these models may not be able to track changes in high mountain ecosystems. Although, only climate variables were assessed, species distribution results were accurate as model evaluation metrics revealed and static factors believed to be modulating species distribution were either a function of climate or influenced climate at a point. Species investigated in this paper were more sensitive to temperature than precipitation related variables, an indication that understanding temperature dynamics under climate change could be critical if active management of these species was considered. Poa annua (48.2 – 49.7%) distribution was unlikely to be adversely affected by elevated CO₂, contrary to the well-established notion that increased atmospheric CO₂ concentration will undermine grass species by favouring woody vegetation. Habitat suitable for Leucosidea sericea will decline under climate, contrary to conventional belief in southern Africa that it was expanding its range under climate change. Elevated CO₂ was likely to benefit V. phosphorica and A. dealbata given that their suitable habitat will increase under climate change. Most of the investigated species were largely specialists as their suitable hbitats were mainly restricted to specific mountains under current and future climate. An improved understanding of climate change in mountain systems through better representation of mountain climates in climate change models will enhance the accuracy of species distribution models.

Abstract ID 558 | Date: 2022-09-13 14:06 – 14:18 | Type: Oral Presentation | Place: SOWI – Aula |

Cavieres, Lohengrin; Valencia, Graciela; Mihoc, Maritza

Over a thousand non-native species have become naturalized in alpine habitats worldwide, and their spread may pose a threat to these vital ecosystems. However, little is known about the impacts of the presence of these invasive species on the native biota, particularly on aspect directly related with ecosystem functioning. In this study we assessed if the presence of non-native species affects the functional spectrum of plant communities at different elevations in the central Chilean Andes. We sampled vegetation patches dominated by the non-natives and patches dominated by native species at different elevations between 2000 and 3600 m a.s.l. We measured a series of functional traits related to reproduction (seed size, flower color) and growth (size, SLA, N leaf content, C/N leaf ratio) as well indicators of nutrient cycling in soils.

In general, functional diversity indices indicated that patches dominated by the non-natives did not differ from patches dominated by natives, although at lower elevations there was a trend for decreased functional diversity in the non-natives patches. In contrast, assessments of total functional volume indicated that, regardless elevation, patches dominated by non-natives had a bigger functional volume than native patches. Thus, non-native species contain different functional traits compared to natives. However, indicators of ecosystem functioning showed no effects of the presence of non-native species. Thus, a complex network of site-specific responses and effects were observed, opening questions about the real impact of non-native species on the native vegetation and how this can vary in the future.

Fondecyt-1171005, 1211197 & FB 210006.

Abstract ID 736 | Date: 2022-09-13 14:18 – 14:30 | Type: Oral Presentation | Place: SOWI – Aula |

Payne, Stephanie Louise (1); Alison, Jamie (2); Høye, Toke Thomas (2); Steenhuisen, Sandy-Lynn (1)

Climate change is a significant driver of the range-expansion of plant and invertebrate species. However, effects of climate are often mediated by plant-animal interactions. For example, as flowering plants expand their ranges to higher elevations, they may be limited by an absence of compatible pollinators. Similarly, effects of plant species’ range expansion on invertebrates, including pollinators and herbivores, are also likely. However, in montane regions, baseline data to measure the impacts of climate change on ecosystems are often lacking. As a result, we are unable to accurately predict and mitigate the effects of range-expanding species on wider biodiversity.

We begin to address this issue in the South African component of the globally collaborative RangeX project. Twenty-five time-lapse cameras were deployed in the Maloti-Drakensberg Transfrontier Park, South Africa, at two sites spanning a large elevational gradient. Within the high elevation site, focal plants were transplanted to elevations beyond their native range and allocated one of two treatments: within open-top chambers, which create a warming effect, or an open control. These cameras recorded animal abundance, plant-animal interactions, and phenological changes of plants across the 2021/2022 summer and autumn seasons, both in terms of indigenous biodiversity and introduced plants. We report on baseline results of the summer and autumn seasonal invertebrate abundance and diversity, as well as the changes in greenness and phenology of focal plants, across elevations and between treatments. Specifically, we report effects of elevation and warming on the abundance and phenology of insects of the Orders Lepidoptera, Orthoptera, Coleoptera, Hymenoptera and Diptera. These data provide valuable information pertaining to the colonisation potential of range-expanding species, indicating (1) whether interactions with animal species may limit or facilitate their expansion and (2) how plant species, in turn, may influence the abundance of wild pollinators and herbivores.

Abstract ID 299 | Date: 2022-09-13 14:30 – 14:42 | Type: Oral Presentation | Place: SOWI – Aula |

Geppert, Costanza (1); Bertolli, Alessio (2); Prosser, Filippo (2); Marini, Lorenzo (1)

In mountain ecosystems, on-going environmental changes are imposing multiple threats to plant populations. Despite a growing body of empirical research on plant redistribution dynamics in mountains, there has been no attempt to test simultaneously the effect of climate and land-use change on the response of threatened, common and alien species along complete elevational gradients. Using a high-resolution distribution dataset of native and alien plants throughout the Trento Province, NE Italy, we could reconstruct the response to global change of c. half of the plant species of the European Alps over the last 30 years (1990 – 2019). We found that most threatened natives have not been able to track climate warming and have experienced a strong erosion of rear margins. As a result, over the last 30 years, the overall range of threatened natives has contracted. By contrast, alien species have expanded their range by moving upwards at the leading edge at climate change speed. Contrary to previous results and climate change expectations, we showed that the current level of threat was higher for warm- than cold-adapted native species. In addition, the level of threat decreased with increasing species competitive ability to thrive under high-resource environments. These patterns suggest that intensive land-uses might be more important drivers of local extinction than temperature warming, at least in the short-term. Finally, we found that hotspots of occurrence of threatened native plants overlapped with hotspots of alien species, and were strongly associated with low elevations, stressing the urgent need of protecting low elevation areas. Opposite to the conclusions of similar studies, the comprehensive sampling in this dataset including threatened species showed that native plants at low elevations are those more at risk of local extinction, probably due to the compounded effect of climate warming and land use change.

Abstract ID 530 | Date: 2022-09-13 14:42 – 14:54 | Type: Oral Presentation | Place: SOWI – Aula |

Geange, Sonya Rita (1,2); Donnellan Barraclough, Alicia (1); Wedegärtner, Ronja (3); Urbach, Davnah (4); Cavieres, Lohengrin (5); Chisholm, Chelsea (6); Lembrechts, Jonas (7); Mcdougall, Keith (8); Pauchard, Aníbal (5); Pizaro, Cristóbal (5); Rashid, Irfran (9); Seipel, Tim (10); Snethlage, Mark (4); Vandvik, Vigdis (1,2)

Invasive species are a major driver of change in global biodiversity and ecosystems. However, knowledge on the impact of invasive species’ on biodiversity, nature’s contributions to people, and human well-being in mountains is currently lacking. Are there differences in perceived impacts on ecosystem functions and nature’s contributions to people between IPBES regions and stakeholder groups? And how is this different between plants, animals, and microorganisms? – We conducted a global survey across IPBES regions and a broad range of stakeholders, including managers, land-owners, farmers, policy makers, conservation, and scientists. Over 600 respondents from all IPBES regions answered the MIREN survey on alien invasive species impacts in mountain regions. Our work provides perspectives on the impacts of invasive species on water, soil, biodiversity, pollination and disturbance processes along with their role in resource provisioning, human safety, human health, recreation and culture across regions and stakeholder groups. Across all stakeholder groups and regions, biodiversity was generally seen to be overwhelmingly negatively affected by invasive alien species, whereas ecosystem services such as resource provisioning were also positively impacted. Regional differences in perception of impacts are larger than those between stakeholder groups. Respondents from the Americas, and government officials rated impacts as most negative, while respondents from Asia and the Pacific tended to be more positive, particularly for ecosystem services.Overall, there is concordance between invasive alien species’ impacts on ecosystem functions and services, suggesting that management to safeguard biodiversity will benefit people, and vice versa. Additionally, we assessed what sources of information guide invasive species management, who is involved, and how such activities are funded. Local management plans are the main source of guidance for management across regions. We hope the insights from our survey will serve to inform policy and foster collaborative action towards sustainable management practices for invasive species in mountain regions.

Abstract ID 753 | Date: 2022-09-13 16:00 – 16:12 | Type: Oral Presentation | Place: SOWI – Aula |

Cortegoso Galmán, Andrea (1,2); Alexander, Jake M. (3); Daehler, Curtis C. (4); Winter, Marten (2); Seipel, Tim (5); Cavieres, Lohengrin A. (6,7); Haider, Sylvia (1,2)

Darwin’s Naturalization Conundrum (DNC) states that non-native taxa closely related to the native community are either more likely to succeed because shared adaptations help them to overcome environmental filtering, or less likely to establish due to strong competition with their native relatives. However, studies conducted so far failed to find general patterns. One reason behind the inconsistencies might be that biotic competition and environmental filtering have been considered mutually exclusive forces, but these mechanisms can operate alternately depending on the environmental conditions. Elevational gradients are powerful tools to evaluate the relative role of both mechanisms for community assembly. At low-elevation environments characterized by stronger biotic interactions, competition should be the dominant structuring force, leading to patterns of phylogenetic overdispersion and favouring the establishment of phylogenetically distinct non-native species. Alternatively, in high-elevation environments with low productivity, community assembly should be mainly driven by environmental filtering leading to patterns of phylogenetic underdispersion and favouring the establishment of closely related species. Community assembly is also affected by human disturbances. Disturbance reduces competition favouring the establishment of closely related species. Along elevational gradients, reduced competition in disturbed habitats should have a stronger impact on community assembly at low elevations. To test these predictions, we performed a global evaluation of DNC studying phylogenetic relatedness of non-native plant species to the native community along elevation gradients comparing natural and disturbed (roadside) habitats. We recorded data for 4000 native and non-native species in plant communities across 17 regions worldwide. We constructed a phylogenetic tree for all species and measured phylogenetic distances from non-native to native species in each plant community. We found a global effect of elevation on the phylogenetic distance of non-native species to the native community: with increasing elevation, non-native species were more closely related to native species. In addition, we found an effect of disturbance on the phylogenetic relatedness, where non-native species were less similar to the native community in disturbed roadside plots. The elevational pattern in phylogenetic distance was stronger at the roadside habitats. Overall, we show that role of environmental filtering and competition for the establishment of non-native species depend on the environment and it is influenced by human disturbances. Our study provides new insights into the mechanisms driving the successful establishment of non-native species in plant communities, something paramount to counteract the negative effects of new invasions under global change.

Abstract ID 275 | Date: 2022-09-13 16:12 – 16:24 | Type: Oral Presentation | Place: SOWI – Aula |

Buhaly, Meike Liv (1); Ratier-Backes, Amanda (1,2); Arévalo, José Ramón (3); Haider, Sylvia (1,2)

Under the influence of a rapidly warming climate, plant species are able to expand their native or introduced ranges to environments which are now more suited to their niche. The rate at which species are expanding and their impact on community diversity, specifically in highly vulnerable mountainous regions, is currently not well documented. Moreover, increasing anthropogenic influence and disturbance are likely to further support such range expansions.

This study aims to investigate how non-native plant species impact taxonomic, phylogenetic, and functional beta-diversity along a steep elevational gradient on the island of Tenerife, covering almost 2500m in elevation. Additionally, we evaluate the role of non-native species in temporal shifts in community diversity over 14 years. Using species composition and abundance data collected by MIREN (Mountain Invasion Research Network) along three mountainous roads in Tenerife, we can further compare whether spatial and temporal changes differ between easily disturbed roadside sites and more natural interior sites away from roads.

First results of this study suggest that an increase in non-native species leads to an increase in taxonomic beta-diversity on both spatial and temporal scales. The addition of non-native species elicits an increase in the dissimilarity between neighboring sites, more significantly in interior sites than roadside sites. In contrast, across years, roadside sites have become more dissimilar than interior sites. Overall, the effect of species turnover was stronger than the nestedness effect.

These findings are in contrast to previous observations which reported biotic homogenization as a consequence of species invasions. However, we assume that our findings reflect a transitional stage with non-native species not having yet reached stable populations. This is evident by the high rate of turnover between years, specifically in low elevation disturbed roadsides. Hence, as non-native species see expansions in their ranges, our preliminary findings may not hold true into the future and sites may become more similar across elevational ranges and over time.

Abstract ID 601 | Date: 2022-09-13 16:24 – 16:36 | Type: Oral Presentation | Place: SOWI – Aula |

Clavel, Jan

• The mutualistic association between mycorrhizal fungi and plants shapes plant communities. However, in the context of increasing human pressure on natural ecosystems, much remains to be learned about the impact of anthropogenic disturbances on the biogeography of mycorrhizal types.
• Making use of a unique database of plant community surveys from 1980 plots along mountain roads in 11 mountain regions across the globe we investigated the impact of anthropogenic disturbance on the distribution of mycorrhizal types across ecosystems.
• We found that roadside disturbance significantly increased the proportion of arbuscular mycorrhizal (AM) associated plant cover compared to adjacent undisturbed vegetation, and especially so in locations dominated by ectomycorrhizal (EM) and ericoid-mycorrhizal (ErM) plant communities.
• Furthermore, non-native plant species, themselves often AM-associated, were more successful in both natural and disturbed environments dominated by AM associations.
• We conclude that changes in mycorrhizal association types caused by anthropogenic disturbance play an important role in mediating the impact of human activity on mountain ecosystems, promoting AM-dominated systems and consequently weakening biotic resistance against non-native species invasion. These results have important implications for vegetation restoration worldwide, as they suggest that roadside disturbance changes the fundamental make-up of EM- and ErM-dominated plant communities.

Abstract ID 185 | Date: 2022-09-13 16:36 – 16:48 | Type: Oral Presentation | Place: SOWI – Aula |

Broadbent, Arthur (1); Bahn, Michael (2); Prtichard, William (1); Newbold, Lindsay (3); Goodall, Tim (3); Guinta, Andrew (2); Snell, Helen (1); Cordero, Irene (1); Michas, Antonios (4); Grant, Helen (3); Soto, David (3); Kaufmann, Ruediger (2); Schloter, Michael (4); Griffiths, Robert (3); Bardgett, Richard David (1)

Native plant range expansions are a widespread consequence of climate change, particularly in mountain ecosystems where shrublines are rapidly advancing into alpine grassland and tundra. At same time, alpine grasslands are experiencing large reductions in winter snow cover and earlier spring snowmelt. Yet, the combined effects of shrub expansion and changing snow conditions on abiotic and biotic soil properties remains poorly understood. We used complementary field experiments to show that reduced snow cover and earlier snowmelt have effects on soil microbial communities and functioning that persist into summer. However, ericaceous shrub expansion modulates a number of these impacts and has stronger belowground effects than changing snow conditions. Ericaceous shrub expansion did not alter snow depth or snowmelt timing, but did increase the abundance of ericoid mycorrhizal fungi and oligotrophic bacteria, which was linked to decreased soil respiration and nitrogen availability. Moreover, by combining molecular sequencing, enzyme assays, greenhouse gas flux measurements, soil biogeochemical analyses, and ¹⁵N labelling, we show that reduced winter snow cover and shrub expansion alter the seasonal dynamics of plant resource acquisition, which is associated with shifts in the temporal dynamics of soil microbial community composition, functioning, and biogeochemical cycling. Our findings suggest that changing winter snow conditions have cross-seasonal impacts on biotic and abiotic soil properties, but shifts in vegetation will modulate belowground effects of future alpine climate change.

Abstract ID 471 | Date: 2022-09-13 16:48 – 17:00 | Type: Oral Presentation | Place: SOWI – Aula |

Forero, Leslie Ellen (1); Jämtgård, Sandra (1); Alexander, Jake (2); Kardol, Paul (1)

As climate change accelerates, plant species must either experience population reductions or shift their ranges to stay within their species’ range of tolerance to climatic variables. However, plant species vary in their ability to shift ranges, depending on dispersal traits, their relationship with chemical and physical soil properties but also the way in which they interact with soil organisms. For example, plant interactions with soil enemies or soil mutualists at the invasion front can either promote or hinder range expansion.

Herein we test soil processes associated with plant range expansion at two mountain sites using elevation as a proxy for the invasion front of range-expanding species. For each of two regions (Norway, Switzerland), we selected range-expanding plant species from within three functional groups (graminoid, forb, and legume). We compared plant growth on sterilized soils to growth on soil inoculated with biota sourced from 1) within the range of the species or 2) beyond the range of the species. This design allows us to test whether release from soil enemies or enhanced interactions with soil mutualists were responsible for plant range expansions. In addition, we replicated the experiment with 5 degrees of warming to project how climate change might impact plant-soil feedbacks and future range expansions. Results are paired with field observations of the same species’ growths in community contexts under ambient and warmed conditions.

Abstract ID 211 | Date: 2022-09-13 17:00 – 17:12 | Type: Oral Presentation | Place: SOWI – Aula |

Iseli, Evelin (1); Phinney, Nathan Harris (2); Gwate, Onalenna (3); Alexander, Jake (1)

Plant species around the world are shifting their geographical distributions along elevational and latitudinal gradients in response to climate change. The resulting reassembly of plant communities has the potential to modify the effects of climate change on biodiversity and ecosystem functioning. However, range shifts generally lag behind predictions made based on the current pace of climate warming, suggesting limiting factors other than just climate. Possible factors affecting species’ ability to successfully disperse and establish in a new environment include (i) their intrinsic dispersal ability, (ii) novel biotic interactions, and (iii) novel abiotic conditions. To determine the contributions of these drivers to dispersal and establishment success of native range expanding plants, we established a large in-situ warming and environmental manipulation experiment in South Africa, Norway, China and Switzerland in 2021. We simulate the introduction of native range-expanding species into high elevation plant communities by transplanting seedlings and seeds above the species’ current range edge, using various experimental treatments to test the effects of both biotic interactions and artificial warming. Population growth and establishment success will be estimated by collecting demographic data across two growing seasons. Here, I will present early results of the first year of the experiment, focusing on dispersal limitation of range expanding species.

Abstract ID 676 | Date: 2022-09-13 17:45 – 17:47 | Type: Poster Presentation | Place: SOWI – Garden |

Guerrero, Lynda Cárdenas (1); Inomoto, Mario Massayuki (2); Buscardo, Erika (3,4); Nagy, Laszlo (1)

The success of plant introductions has partly been explained by their presumed escape in their new environment from their natural enemies (e.g., herbivores and pathogens) that occur in their natural range (enemy release hypothesis – ERH). Improved growth and reproductive potential may lead to a rapid spread from the site of introduction and species may become invasive, such in the case of several species of Pinus introduced in the southern hemisphere. This may have been facilitated by their association with ectomycorrhizal fungi (as opposed to the prevalent arbuscular mycorrhizal (AM) symbiosis in the southern hemisphere) that may have afforded better protection from soil-borne pests and pathogens, such as nematodes. To test the ERH, we quantified nematode loads in P. elliottii plantation, under pine individuals growing in open grassy-shrubby vegetation (locally called ‘campo’), under herbaceous and shrubby species of the campo and in the native rain forest AM conifer Araucaria angustifolia.

Morphological identification was made, and the nematodes were assigned to trophic groups. We found that overall, nematodes were less abundant in the Pinus stand and under Pinus trees in ‘campo’ than under Araucaria and ‘campo’ species. Root-feeding nematodes were the most abundant trophic group overall; they were least abundant in the Pinus stand and under Pinus trees in ‘campo’. Fungal feeders were not different between vegetations with or without Pinus. We suggest that the ERH appears to support the success of establishment and invasiveness of P. elliottii, characterised by a reduced root-feeding nematode load in comparison with species in native vegetation. Nevertheless, to conclusively assess the existence and magnitude of enemy release, additional biogeographical comparisons between natural enemies in the native and exotic habitats of P. elliottii are necessary.

Abstract ID 553 | Date: 2022-09-13 17:47 – 17:49 | Type: Poster Presentation | Place: SOWI – Garden |

Pauchard, Aníbal (1,2); Eduardo, Fuentes-Lillo (1,2); Alejandra, Jiménez (1,2); Rafael, García (1,2); Lohen, Cavieres (1,2); Ramiro, Bustamante (3,2); Sylvia, Haider (4,5)

Human-driven species movement and species local losses are causing the homogenization of global biota is occurring at an unprecedented rate, with uncertain consequences for biodiversity and ecosystems at global, but also at local or regional scales. Biotic homogenization not only encompasses a change in species composition, but species additions and extinctions can modify not only the taxonomic diversity but also the phylogenetic structure of the community and the overall function of the ecosystem. Our project has aimed to understand current patterns of mountain biodiversity and how human-driven factors have affected these patterns, specifically we have studied the taxonomic, phylogenetic and functional homogenization of plant communities in the Chilean Andes from 32 to 53 degrees south latitude, from near sea level to 3,500 m.a.s.l. We used a standardized-systematic method of field data collection across two environmental gradients (elevation, latitude) to better understand how biological invasions are causing taxonomic homogenization and what are the current distribution patterns of non-native plants in the Andes. We based our approach on the Mountain Invasions Research Network (MIREN) T-survey protocol and constructed a comprehensive plant community dataset to address these questions. We hypothesized that, non-native plant richness and abundance decreases with elevation and latitude, with roads being the primary driver to explain the presence of non-native species in the Andes. Additionally, we hypothesized that along elevational and latitudinal gradients in mountain ecosystems, non-native species homogenize plant communities along taxonomic dimensions and that this process is driving disturbance and non-native lowland plant groups. The results showed that the richness and abundance of non-native species decreased with elevation and latitude, while when comparing disturbed and undisturbed sites, no significant differences were observed in the richness and abundance of non-native plants. While beta diversity (β) increases with elevation but decreases when comparing disturbed and non-disturbed areas. These results show that disturbance (mainly the presence of the road) explains the distribution patterns of non-native plants in the Andes, in addition to favoring the homogenization of ecosystems. In terms of phylogenetic diversity, we have found a simplification of community structure caused by Eurasian non-native species. Functionally, non-native species add novel traits to native communities but in highly disturbed areas there is a decrease in functional diversity. Our results highlight the need for global studies that account for the multidimensional aspects of biotic homogenization in mountains. Funded by Fondecyt 1180205 and ANID/BASAL FB210006.

Abstract ID 551 | Date: 2022-09-13 17:49 – 17:51 | Type: Poster Presentation | Place: SOWI – Garden |

Meul, Andreas (1); Praeg, Nadine (1); Dainese, Matteo (2); Lembo, Silvia (2); Niedrist, Georg (2); Illmer, Paul (1)

Climate change is affecting the composition and functioning of ecosystems across the globe. In alpine ecosystems, species will have to face new conditions, either by adapting their life to warming or by migrating upwards into a new environment to track their thermal niche. Upwards migrating species will experience no change in temperature but lower atmospheric pressure due to higher elevation. Reduced air pressure affects biologically relevant physical parameters such as vapor pressure deficit, gas diffusivity, and CO₂ partial pressure with possible consequences mostly on plants. Many studies have revealed the effects of changing climate on plant species and their migrations in this context are well described. In contrast, less is known about the ability of associated soil microorganisms to shift their ranges and in particular, the many possible new combinations of shifting and persistent plants and microorganisms and the resulting new interactions. Generally, the impact of moderate pressure reduction on soil microorganisms associated with plants still needs to be investigated.
Thus, main goals of the international UPSHIFT project are i) to assess how soil microorganisms react to lower air pressure in terms of diversity, functional traits, and biomass production and ii) to investigate new and altered interactions with upwards migrating plants. For that purpose, we will set up a gradient design by lowering the air pressure to simulate four elevational levels (200, 1500, 2500, and 4000 m a.s.l.) in hypobaric chambers (terraXcube) while temperature, humidity, and solar radiation are kept constant according to ambient conditions of 1500 m. For each scenario, the reaction of common microbial test strains as well as some typical soil microorganisms will be investigated, both in pure and mixed cultures. Additionally, the impact of decreased air pressure on soil microbial diversity will be determined along with studies on the interactions between plants and soil microorganisms from both the bulk and rhizosphere fraction.

The UPSHIFT project is the first attempt that we know of to assess the effects of atmospheric pressure on (soil) microorganisms and plant-microbe interactions in the context of climate change. This is essential due to the upward migration of plants and the profound consequences for the functioning of alpine ecosystems.

Abstract ID 825 | Date: 2022-09-13 17:51 – 17:53 | Type: Poster Presentation | Place: SOWI – Garden |

Zernichow, Camilla (1); Gya, Ragnhild (1,2); Töpper, Joachim Paul (1,4); Olsen, Siri Lie (3,4); Östman, Silje Andrea Hjortland (1); Egelkraut, Dagmar (1); Klanderud, Kari (3); Vandvik, Vigdis (1,2)

Anthropogenic climate change is a threat to biodiversity with alpine plant communities being especially vulnerable. Warming gives lowland species, the opportunity to colonise the alpine and create no-analog plant communities. Importantly, the functional identity of the lowland species may be novel to alpine communities and thus introduce novel biotic interactions. Most lowland species are more competitive than alpine species indicating that alpine species could potentially be outcompeted under future climate conditions. Climate scenarios predict regional changes in precipitation in addition to warming, which raises the additional question how warming effects interact with different precipitation regimes. In our study, we focus on the diversity of alpine plant communities and how different aspects of diversity change under climate warming. For instance, species richness decreases with elevation due to adverse environmental conditions in the alpine compared to lower altitudes. Under climate warming, richness has been shown to increase in alpine systems due to colonization by species from lower altitudes. However, what effects these colonizers may have on the diversity of the original alpine communities in addition to warming is poorly understood and studied. Previous findings, however, indicate a possible response lag for the community compositions richness.

I order to shed light on this knowledge gap, our study uses an innovative experimental approach to simulate the predicted climate warming combined with novel biotic interactions in the field. The experiment is conducted at the four alpine sites in the Vestland climate grid in Norway. Our sites are located along a precipitation gradient ranging from 1000-3500 mm/year. We use open top chambers (OTCs) for warming. To test for functional rather than species identity novelty in the alpine community, we transplanted three lowland species with functional traits new to the alpine vegetation (novel trait species), and three lowland species with functional traits similar to the new alpine vegetation (extant trait species). We collected plant community data in a full-factorial design of these experimental treatments including control plots without warming and/or transplants in 2018, 2020. We will collect these data once more this summer and analyse them test the following hypothesis:

1. We expect warming to reduce diversity in the alpine communities.
2. New neighbours will have a general negative impact on the diversity due to enhanced competition.
3. Novel trait species will reduce diversity more than extant trait species.
4. Along the precipitation gradient we expect that the warming effects decrease and competition effects increase.

Abstract ID 234 | Date: 2022-09-13 17:53 – 17:55 | Type: Poster Presentation | Place: SOWI – Garden |

Achermann, Marc Alexander (1); Gwate, Onalenna (2); Clark, Vincent Ralph (2); Chiarucci, Alessandro (1)

In mountain areas globally, both native and non-native plants are expanding their ranges along elevational gradients in response to global change. The Maloti-Drakensberg (MD) is one of southern African’s centres of endemism and is part of a regional biodiversity hotspot, but one in which there is limited data on species’ range expansions. The aim of this study is to increase our knowledge of range-expanding species in the MD by establishing two new long-term Mountain Invasion Research Network (MIREN) road transects, using the MIREN protocol (https://www.mountaininvasions.org/) for roads and trails where relevant. The Mont-aux-Sources road transect ranges from the urban edge of Phuthaditjhaba (1,900 m) to near the summit of the Amphitheatre on Beacon Buttress (3,150 m) (South Africa) via the Witsieshoek road to the Sentinel Car Park and along the Sentinel Trail to via the Chain Ladders. The second road transect at Holomo Pass is entirely a path transect (Maqeleng) in Tsê’hlanyane National Park (Lesotho), with elevation range from 1,990 m to 2,670 m. In summary, the Miren protocol involves 20 sampling sites per road transect, placed on equal elevational bands (Mout-aux-Sources = 60 m and Holomo = 33 m bands) from the bottom to the summit. Each site consisting of three plots (for roads 50 x 2 m dimensions; for paths = 10 x 2 m dimensions). The first plot is orientated adjacent to the road; the two other plots are orientated perpendicular to the first one, forming a T-shape. The plots will be re-sampled every five years, to determine any evidence of non-native and key native species moving upslope. The Mont-aux-Sources transect is important due to the large numbers of domestic and foreign tourists accessing the high MD, and provides the opportunity for early-detection of non-native species; in addition, plans to resurface the Witsieshoek road may bring in propagules of non-native species – a long-term monitoring plan such as MIREN will assist with due diligence and rapid response. Currently, non-native species richness was higher (p < 0.05) at elevations < 2,500 m compared to > 2,500 m; the highest-elevation non-native known so far is the grass Poa annua, located at 2,800 m in the Chain Ladder gully. The statistical analysis is performed with Rstudio. At present, various factors could be “keeping” non-native species out of the higher elevations: a non-saturated habitat envelope from expansion lag, an inhospitable austro-alpine climate >2,800 m, or simply a lack of detailed assessments.

Abstract ID 435 | Date: 2022-09-13 17:55 – 17:57 | Type: Poster Presentation | Place: SOWI – Garden |

Santoianni, Lucia Antonietta; Innangi, Michele; Carranza, Maria Laura; Stanisci, Angela

The Mediterranean region is characterized by high levels of plant diversity along with a relevant endemism rate and it has been designated as one of “biodiversity hotspot” of the world. Across the Mediterranean region, several mountain ranges represent a “hotspot within the hotspot” due to their geological and climatic history. Yet, these mountains are experiencing significant changes in biodiversity for their sensitivity to land-use changes and are threatened by the on-going climate change.

On a world-wide scale, invasive alien plants (IAPs) are a growing threat to biodiversity, causing significant ecological and economic losses. Although there is a great number of published researches dealing with invasive alien plants across different ecosystems, a systematic review of IAPs occurrence and invasiveness on Mediterranean-climate mountain region is still lacking.

In this work, we provide an overview of the published ecological studies dealing with invasive alien plants across the Mediterranean mountain ecosystems of the last 10 years. This review sets out a checklist of invasive alien plants recorded in these mountain areas, analyzing taxonomic families and life-forms composition, geographic distribution and habitat preference. Our work contributes to increasing knowledge on this topic, creating a database which could be used to develop further research and appropriate management and conservation strategies across Mediterranean mountain ecosystems.

Abstract ID 331 | Date: 2022-09-13 17:57 – 17:59 | Type: Poster Presentation | Place: SOWI – Garden |

Lembo, Silvia (1); Illmer, Paul (2); Niedrist, Georg (1); Praeg, Nadine (2); Meul, Andreas (2); Matteo, Dainese (1)

Climate change is altering the elevation range limits of many organisms, often driving upward range shifts. This can have direct eco-physiological effects on species, but also indirect effects that are caused by alterations in the way species interact with one another. Organisms that migrate upwards to track their thermal niche will experience no change in temperature but decreasing air pressure the higher they migrate. This will affect biologically relevant physical parameters such as vapour pressure deficit (VPD), CO2 partial pressure, and gas diffusivity involved in fundamental ecological processes, including evapotranspiration, photosynthetic activity or respiration. Consequently, reduced air pressure poses a potentially novel environmental problem for upwards migrating organisms to solve if they are to persist at high elevation as climate change continues. In this context, the impact of lower atmospheric pressure on upwards migrating plants and their novel associations, are largely unknown. Here, we introduce a new project UPSHIFT that will address this knowledge gap by applying novel experimental approaches to uncover the mechanisms underlying species, community and ecosystem responses to lower air pressure in alpine grasslands. The present contribution focuses on an overview of the experiments that will be carried out. These aim at (i) understanding how upwards migrating plant species react to lower air pressure (ii) assessing how upwards migrating plants perform with novel plant competitors and novel soil organisms, and (iii) evaluating the effect of lower air pressure on the ecosystem water balance. Our experimental approach will integrate a next generation controlled environmental facility to simulate different alpine climate conditions, pot and mesocosm (lysimeter) experiments to disentangle the effects, and field observations to validate the reliability of the obtained results. In particular, UPSHIFT is based on a unique environment simulator (terraXcube https://terraxcube.eurac.edu/) that is able to control different parameters such as barometric pressure, temperature, humidity, concentration of several gases (CO2 and O3) and solar radiation. For all the experiments, a gradient design will be set up at the terraXcube, in which four elevation will be simulated (200- 1,500-2,500-4,000 m). During the experiments different ecophysiological, chemical and microbial indicators will be measured to gain insights into fundamental ecological processes. In summary, UPSHIFT is the first attempt to include reduced air pressure to comprehensively anticipate the ecological impacts of climate change in alpine ecosystems.

Abstract ID 477 | Date: 2022-09-13 17:59 – 18:01 | Type: Poster Presentation | Place: SOWI – Garden |

Gya, Ragnhild (1,2); Töpper, Joachim Paul (1,3); Olsen, Siri Lie (4,5); Lieungh, Eva (6); Östman, Silje Andrea Hjortman (1); Egelkraut, Dagmar Dorothea (1); Vandvik, Vigdis (1,2)

Climate change will alter alpine plant communities both directly and indirectly. Directly through the physiological responses to increased temperature, and indirectly through both changes in interactions within extant plant communities, and novel species interactions by range-expanding species. Such indirect effects have been found to be of overriding impact, to the extent that they can modify or even reverse the direct response of plants to climate changes. For example, alpine species interactions switch from facilitative to competitive as climate becomes more benign. Additionally, climate change is already causing accelerating range-expansions of species into alpine communities. These shifts are happening faster than the alpine species are able to adapt by moving which creates novel species interactions with species which have not coexisted previously. A lot is known of the direct effects of climate change on alpine plants, while the indirect effects have been less studied.

The extent and severity of an alpine species population decline in response to climate change depend on the different underlying vital rates of the population. The specific changes in survival, reproduction, or growth have different implications for e.g., genetic variability in the population. A mechanistic understanding of these changes is therefore important to understand the long-term consequences for alpine plants to different climate change effects.

In this study we present the population dynamics of the alpine species Veronica alpina and Sibbaldia procumbens in a field experiment testing the relative effects of warming, changes in interactions within alpine communities, and colonization by lowland plant species. We followed the fates of all individuals in the experiment over four years and built Integral Project Models (IPM) for every experimental treatment. By combining i) warming experiments with open top chambers, ii) removal experiments with removal of all above ground biomass except the two study species, and iii) transplant experiments of lowland plant individuals, we test the direct and indirect effects of climate change on these two alpine species. To separate the direct effect of warming from the indirect effect of changes in plant interactions we compare the removal experiment to the controls, with and without warming. By comparing the transplant treatments with controls, with and without warming, we test the effect of novel colonizing species in the extant climate and a warmer climate. We expect to see the largest population decline in the combined treatment with warming plus introduction of novel plants.

Abstract ID 403 | Date: 2022-09-13 18:01 – 18:03 | Type: Poster Presentation | Place: SOWI – Garden |

Hiltbrunner, Erika; Von Büren, Raphael S.

Explaining why a species does exist where it does, is the number one issue in ecology. However, the actual range limits of alpine plant species are still largely unexplored and unexplained. We aim at identifying the low temperature range limits of two highly abundant graminoid species that intermingle in mosaics of high-elevation habitats across the European Alps: the sedge Carex curvula and the grass Nardus stricta. We assessed the year-round temperature 3 cm below ground, close to the plant meristems as well as snow cover duration, soil chemistry and vegetation characteristics (composition, Landolt indicator values) in 115 well-characterized microsites, and combined the field data with freezing resistance using different approaches such as electrolyte leakage for leaves, tetrazolium vital staining for shoots, and regrowth capability for entire tussocks.Carex and Nardus clearly segregated across different microsites. Season length, growing degree hours and soil chemistry (pH, C/N-ratio, phosphorus) did not demarcate the two species’ ranges, while their distribution was strongly affected by soil temperature minima in winter. Carex occurred at sites with and without protecting snow cover and resisted low soil temperatures (-13 °C). Nardus was absent at microsites with short snow cover duration (less than 5 months) and soil minimum temperatures below -5 °C. During the growing season, leaves of Carex had a higher freezing resistance with LT50 of -16.1 °C than those of Nardus with LT50 of -13.3 °C (LT50: lethal temperature for 50% of the tissue). Tetrazolium vital staining in young shoots also revealed a higher freezing resistance in Carex compared to Nardus, and shoot apices tolerated lowest temperatures in both species: Carex -30 °C, Nardus -24 °C. However, a vital shoot apex alone did not ensure regrowth after winter. Regrowth after severe frost events requires intact vessels and roots, all less freezing tolerant than apical meristems and young leaves.

The cold range limits of widespread alpine graminoid species are evidently set by thermal extremes in winter and not by gradual thermal constraints in growth and development. Microtopography, thus snow distribution pattern, combined with the species’ freezing resistance explains the cold edge of the fundamental niche of these two prominent species. To our knowledge, this is the first mechanistic explanation of species range limits in cold environments. Previous attempts have mainly employed mapping approaches and correlative analysis.

Abstract ID 409 | Date: 2022-09-13 18:03 – 18:05 | Type: Poster Presentation | Place: SOWI – Garden |

Fuentes, Eduardo (1,2,4); Pauchard, Anibal (1,2,4); Lembechts, Jonas (3)

Plant invasions have become increasingly common in mountains worldwide, therefore, understanding which factors determine the invasion and at what scale they operate are fundamental for decision-making in the conservation of mountain ecosystems. Although patterns of non-native species in mountain ecosystems have been widely described, little is known about what specific abiotic, biotic, or anthropogenic factors are driven such patterns. Here, we assessed the relative importance of anthropogenic, biotic, and abiotic factors at two spatial scales as drivers of plant invasions along three roads in the Andes of south-central Chile. We sampled non-native plant richness and abundance, and each of these explanatory factors, in-situ in 60 transects in disturbed areas and adjacent undisturbed vegetation. Low elevation areas were the most invaded, with patterns of richness and abundance driven mainly by anthropogenic factors, explaining between 20 and 50% of the variance for the three roads. Only for the abundance of non-native species along the road in the Malalcahuello National Reserve, biotic factors were more important (45% of the variance). At the regional scale, the abundance of non-native species was again explained best by anthropogenic factors (24% of the variance), yet non-native richness was driven most strongly by abiotic factors such as soil nitrogen content and pH (15% of the variance). Our results confirm the conclusions from experimental studies that anthropogenic factors override abiotic factors and are important drivers of non-native species at local and regional scales and that non-native plant invasion in mountains is currently not strongly limited by climate.

EFL and AP Funded by Fondecyt 1180205 and ANID/BASAL FB210006