Thomas Abeli

Some like it hot and some like it cold, but not too much: plant responses to climate extremes

Current climatic models predict increasing frequency and magnitude of extreme climatic events (ECEs). Ecological studies recognize the importance of these extremes as drivers of plant growth and mortality, as well as drivers of ecological and evolutionary processes. Here we review observational and experimental studies on ECEs on herbaceous plants and shrubs. Extreme events considered were heat waves, drought, advanced or delayed snowmelt, heavy rainfalls, frosts, pulsed watering and flooding. We analysed 39 studies dealing with direct response of plant to ECEs in different ecosystems, with a particular focus on cold ecosystems (alpine and arctic). Although the number of studies increases every year, the understanding of ecological consequences of ECEs is fragmentary. In general, ECEs affected negatively on physiological processes (efficiency of photosystem II, stomatal conductance and leaf water potential), productivity and reproduction, and had consequences on population demography and recruitment several years after ECE. Indeed, the plant responses to ECEs were species specific and depended on the plant life stage and the timing of ECE. In fact, the magnitude of the effect of ECEs decreased over the growing season. Drought had the most severe effect on plants, while heat waves had minor effect if water was available. The overlap of different ECEs had an additive effect (e.g. drought associated to heat-waves). In general, both neutral or positive plant responses were found and acclimation is possible. In some cases, ECEs exert a strong selective pressure on plant species.

Is legal protection sufficient to ensure plant conservation? The Italian Red List of policy species as a case study

The conservation of species listed in the Bern Convention and European Directive 1992/43/EEC (so-called policy species) is mandatory for European Union (EU) countries. We assessed the conservation status of Italian policy species, based on the IUCN categories and criteria, to evaluate the effectiveness of existing protection measures at the national level. Among the 203 vascular plants, bryophytes and lichens evaluated, 41.9% are categorized as threatened, and one is already extinct, indicating that the protection measures for policy species are inadequate. Our results for the Italian policy species are consistent with those of an assessment at the EU level. Conservation priorities should be established at both the national and regional scales. An effective conservation strategy is needed, and in situ and ex situ actions focused on threatened species should be promoted.

Are Red Lists really useful for plant conservation? The New Red List of the Italian Flora in the perspective of national conservation policies

“The New Red List of the Italian Flora” includes all the Italian policy species and other species of known conservation concerns for a total of 400 taxa, 65% of which are threatened with extinction. The Red List is based on a huge georeferenced data-set useful for conservation purposes.

Environmentally induced transgenerational changes in seed longevity: maternal and genetic influence

BACKGROUND AND AIMS Seed longevity, a fundamental plant trait for ex situ conservation and persistence in the soil of many species, varies across populations and generations that experience different climates. This study investigates the extent to which differences in seed longevity are due to genetic differences and/or modified by adaptive responses to environmental changes. METHODS Seeds of two wild populations of Silene vulgaris from alpine (wA) and lowland (wL) locations and seeds originating from their cultivation in a lowland common garden for two generations (cA1, cL1, cA2 and cL2) were exposed to controlled ageing at 45 °C, 60 % relative humidity and regularly sampled for germination and relative mRNA quantification (SvHSP17.4 and SvNRPD12). KEY RESULTS The parental plant growth environment affected the longevity of seeds with high plasticity. Seeds of wL were significantly longer lived than those of wA. However, when alpine plants were grown in the common garden, longevity doubled for the first generation of seeds produced (cA1). Conversely, longevity was similar in all lowland seed lots and did not increase in the second generation of seeds produced from alpine plants grown in the common garden (cA2). Analysis of parental effects on mRNA seed provisioning indicated that the accumulation of gene transcripts involved in tolerance to heat stress was highest in wL, cL1 and cL2, followed by cA1, cA2 and wA. CONCLUSIONS Seed longevity has a genetic basis, but may show strong adaptive responses, which are associated with differential accumulation of mRNA via parental effects. Adaptive adjustments of seed longevity due to transgenerational plasticity may play a fundamental role in the survival and persistence of the species in the face of future environmental challenges. The results suggest that regeneration location may have important implications for the conservation of alpine plants held in seed banks.

Conserving plant diversity in Europe: outcomes, criticisms and perspectives of the Habitats Directive application in Italy

Habitat Directive is the core strategy of nature conservation in Europe aiming at halting biodiversity loss. In this study the results of the third Italian assessment regarding the conservation status (CS) of plants listed in the Habitat Directive (Flora of community interest—FCI) was presented. Data was collected from several sources related to plant distribution, population data, habitats and pressures. Following the official European procedure, all parameters were evaluated and combined to give the CS of each taxon in each biogeographical region of presence. A comparison between the recent Italian IUCN and Reporting assessments was performed in order to evaluate the consistency between these two assessments. The official EU checklist comprises 113 Italian plant taxa, 107 of which were examined in this study. Our results showed a critical situation with only 34% of favourable CS, while 50% were unfavourable (40% inadequate plus 10% bad) and 16% unknown, in particular in the Mediterranean bioregion, where the unfavourable assessments reach the 65%. The results of the Report were consistent with those of the IUCN assessment, in which 41.9% of plants were threatened with extinction. This report highlighted some benefits and criticisms at national level, but it may have a wider significance. Although a general advance of knowledge, a great effort is needed to reach the Habitats Directive goals. Despite the limited resources, monitoring activities needs to be improved in order to close information gaps for several plants. A positive outcome was the development of a specific national project funded by the Italian Ministry of Environment, with the ambitious target to set future monitoring activities for FCI and optimize monitoring efforts.

From cold to warm-stage refugia for boreo-alpine plants in southern European and Mediterranean mountains: the last chance to survive or an opportunity for speciation?

During glacial phases of the Quaternary, Southern European and Mediterranean mountains (SEMms: Pyrenees, Apennines, Balkan Mountains, Maritime Alps, etc.) provided suitable habitats for numerous cold-adapted (boreo-alpine) plant species migrating from northern regions, which have been described as cold-stage refugia. Speciation events occurred in these refugia through adaptation and evolution by genetic differentiation; other species still survive as peripheral populations. In the current phase of climate change, SEMms are (macro-)refugia of great interest because they still host important populations of glacial relicts and alpine flora, often in isolated occurrences. Such species can be found in topographic niches generally linked to peculiar landforms such as fossil glacial cirques, scree slopes and gorges that may perform as warm-stage (micro-)refugia. We present a review on the boreo-alpine species living across SEMms with the aim to describe their genetic patterns evolved during Quaternary climatic oscillations as well to highlight the role of microtopographic/microgeomorphologic niches as microrefugium areas under the current scenario of climate change.

Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants

Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence suggest that there may be major implications for future plant population size and structure.

Translocation ecology: the role of ecological sciences in plant translocation

Translocations (sensu IUCN 2013) can be effective conservation tools only if they are undertaken with underpinning science to support the actions and outcomes. Translocations are rarely the simple exercise of moving species and/or populations for conservation purposes, the so-called ‘gardening approach’, rather, behind each translocation there should be a level of pragmatic and focused science to support the actions and to interpret the long-term viability of the action. Godefroid et al. (2011) for example, showed that the success of reintroductions can be at risk with even minor gaps in the knowledge of species biology, habitat requirements, threats, etc., leading to failure. In the past decade, guidelines have been developed to improve the success of translocations (e.g. Maschinski et al. 2012; IUCN 2013; Rossi et al. 2013) on the basis of experiential evidence, but much more effort is required as the increase in the number of threatened taxa outstrips translocation knowledge and technical capacity. Reasons for failure are manifold, but a lack of knowledge of the species ecological requirements and the selection of ecologically suitable translocation sites loom large as constraints. A key to reduce this uncertainty is through a more active dialogue on the successes and failures of rare plant translocation and through greater integration of ecology into conservation matters. This special issue highlights ‘‘The role of ecological sciences in plant translocation’’, assembling 10 articles on different ecological issues relevant to successful translocation. Ecological studies are essential in different phases of a translocation and not just to understand the ecological requirements of a target species. Rare species are often rare because they have life history stages that act as bottlenecks to population growth, they may produce few propagules or propagules may be low in viability or have very narrow conditions for recruitment. All these ecological aspects are relevant in translocation as relevant is the selection of suitable sites for translocations (Bontranger et al. 2014), the identification of inter-specific interactions between a target species and the recipient community (i.e. hybridization, pollinator availability, T. Abeli (&) Department of Earth and Environmental Sciences, University of Pavia, Via S. Epifanio 14, 27100 Pavia, Italy e-mail: thomas.abeli@unipv.it

Living with extremes: the dark side of global climate change

We are pleased to announce a new special issue ofPlant Ecology on extreme weather events.The new report of IPCC (2013) predicts remarkableincrease in global mean air temperatures. Dependingon the scenarios, the best estimates of temperatureincrease range from 1.8 and 4.0 C by 2100. Climatechange may generally act in two ways: gradualwarming will affect plants and vegetation over short(decades), medium (centuries), and long (millenniaand over) timescales, with some effects alreadyevident, including upward altitudinal plant migrationsin mountain regions, species turnover, range shifts andchanges in vegetation patterns (Dullinger et al. 2012).In many cases, increased mean temperature corre-sponds to increased variability, leading to moreextreme temperatures, and increased heat energy inthe atmosphere, which promotes the development andintensity of extreme weather (Easterling et al. 2000).Consequently, climate change is characterized also byunpredictable extreme weather events (EWEs) such asheat waves, extreme droughts, heavy rains, storms andtheir associated effects like increased frequency offires, floods, etc. The occurrence of EWEs has beenmore common in the last 20 years, as a direct effect ofincreased temperatures (Easterling et al. 2000). EWEsmay adversely affect natural ecosystems, crop pro-ductivity and human health, and facilitate biologicalinvasions (Ciais et al. 2005). The recent examples ofEWEs include: the extremely hot summer in SouthernEurope in 2003, when the thermometer marked 40 Cfor several consecutive days, and the exceptionalfloodingofLake Eyre South (South Australia) in2011.However, our understanding of EWEs effects on plantlife and vegetation remains poor. While gradual risingof temperature allows species to adapt or at least toacclimate to the changing environment, extremeweather works like a stochastic event, with rapid andunpredictable effect on plant fitness and survival (Niuet al. 2014).The study of EWEs is in its infancy in the scientificliterature, and it is a promising and pertinent researchfield for the future. To date, most studies of the effectsof EWEs have been published in special issues of plantscience journals, demonstrating that special issuesplay the special role in promoting research in this fieldand summarizing the current state of knowledge.This special issue of Plant Ecology will advanceour ecological understanding of direct and indirecteffects of EWEs on plants, with attention to a broad

Planning for assisted colonization of plants in a warming world

Assisted colonization is one way of facilitating range shifts for species that are restricted in their ability to move in response to climate change. Here we conceptualize and apply a new decision framework for modelling assisted colonization of plant species prior to in situ realization. Three questions were examined: a) Is species translocation useful in a certain area? b) where, and c) how long will it be successful in the future? Applying our framework to Carex foetida in Italy at the core of its distribution and its southern edge revealed that assisted colonization could be successful in short-term (2010–2039) climate conditions, partially in medium (2040–2069) but not in long-term (2070–2099) scenarios. We show that, for some species, it is likely that assisted colonization would be successful in some portions of the recipient site under current and short-term climate conditions, but over the mid- and long-term, climate changes will make species translocation unsuccessful. The proposed decision framework can help identify species that will need different conservation actions (seed banks and/or botanical gardens) when assisted colonization is unlikely to be successful. Furthermore it has broad applicability, as it can support planning of assisted migration in mountainous areas in the face of climate change.