Climate and landscape composition explain agronomic practices, pesticide use and grape yield in vineyards across Italy

Context Worldwide, organic farming is being promoted as one of the main alternatives to intensive conventional farming. However, the benefits of organic agriculture are still controversial and need to be tested across wide environmental gradients. Objective Here, we carried out an observational study to test how agronomic practices, pest management, environmental impact and yield of conventional and organic vineyards changed along wide climatic and landscape gradients across Italy. Methods We used a block design with 38 pairs of conventional and organic vineyards across Italy. Results and conclusions Most agronomic practices did not differ between conventional and organic vineyards. By contrast, landscape composition and climate were strong predictors of management in both systems. First, increasing semi-natural areas around the vineyards reduced pesticide pressure and related environmental impacts, but was also associated with lower yield. Second, irrespective of the farming system, a warm and dry climate was associated with reduced fungicide pressure. Conventional farming had a yield gain of 40% in cold and wet climate compared to organic but the yield gap disappeared in the warmest regions. Significance In both farming systems, we observed a large variability in management practices that was mainly explained by climate and landscape composition. This large variability should be considered when evaluating the benefits and drawbacks of different farming systems under contrasting environmental contexts

Cambiamento globale e dinamica di distribuzione delle piante in ambienti montani: il ruolo dei fattori biotici e abiotici

Nella mia tesi di dottorato ho cercato di comprendere come il cambiamento globale stia modificando la distribuzione delle piante vascolari studiando contemporaneamente il ruolo del surriscaldamento delle temperature e dei cambiamenti di uso del suolo. Oltre agli effetti diretti di questi fattori abiotici ho indagato il ruolo degli insetti fitofagi nel modificare le dinamiche di popolazione e comunità di piante native e esotiche. Nella prima parte della tesi di dottorato, riporto tre studi a breve termine sull'effetto di cambiamento climatico, disturbo antropico e interazioni biotiche sulle dinamiche di insediamento delle piante a scala locale. Nel primo studio, abbiamo condotto un esperimento in semi-campo, disturbando il suolo e manipolando la disponibilità di acqua, di azoto e la pressione degli insetti fitofagi. L'insediamento delle piante è stato modulato dall'azione combinata di fattori biotici e abiotici solitamente poco considerati, come la tempistica della perturbazione del suolo e la fitofagia. Nel secondo studio, ho investigato le stesse tematiche replicando l'esperimento in condizioni naturali nelle Alpi Europee lungo ripidi gradienti altimetrici. I risultati hanno nuovamente sottolineato l’importanza del ruolo degli insetti fitofagi, la cui pressione naturale è in grado di amplificare gli effetti negativi del disturbo del suolo sulle piante native, favorendo così quelle esotiche. Nel terzo studio, ho indagato lungo gli stessi gradienti altimetrici l'abbondanza e la diversità di due gruppi chiave di insetti fitofagi con tratti funzionali contrastanti, cavallette (Orthoptera) e cicaline (Rynchota, Auchenorrhyncha). È stato dimostrato che specie termofile, come le cavallette, saranno probabilmente favorite dal riscaldamento climatico, mentre gruppi più specializzati, come le cicaline, potrebbero essere minacciati dal disturbo antropico. Nella seconda parte della tesi di dottorato, riporto due studi a lungo termine su scala regionale, con i quali sono stati esplorati gli effetti del cambiamento climatico e dell'uso del suolo sulle dinamiche di popolazione e sulla ridistribuzione di specie vegetali native ed esotiche. Nel quarto studio, ho confrontato le risposte al cambiamento globale di piante localmente estinte, a rischio ed esotiche. È emerso che le piante esotiche si stanno diffondendo rapidamente dalle valli, mentre le specie a rischio stanno contraendo la loro distribuzione. La più alta concentrazione di piante estinte, a rischio ed esotiche si trova per tutti e tre i gruppi nelle valli, dove la pressione umana è più forte. Inoltre, nelle valli le specie esotiche possono sostituire facilmente specie native meno competitive. Nel quinto studio, ho analizzato le tendenze demografiche e la distribuzione di circa due terzi delle specie di orchidee alpine. La numerosità della maggior parte delle popolazioni è diminuita e molte specie sono state incapaci di rispondere al riscaldamento climatico poiché si trovavano in habitat degradati e/o frammentati. Questi risultati hanno suggerito che l'interazione tra il cambiamento climatico e il cambiamento dell'uso del suolo provoca il declino delle orchidee. Da questa tesi sono emersi tre messaggi principali. In primo luogo, risulta cruciale adottare un approccio multifattoriale per indagare gli impatti del cambiamento globale sulla distribuzione delle specie. In secondo luogo, è emersa l’importanza delle interazioni biotiche nel modificare le dinamiche di insediamento vegetale. Infine, abbiamo visto come i tratti funzionali delle specie possano migliorare la nostra capacità di prevederne le risposte al cambiamento globale.Understanding the drivers of species redistribution dynamics and determining the role of climate change, human disturbance and biotic interactions are fundamental challenges of ecology and conservation biology. In my PhD thesis, I addressed these issues in the European Alps, a highly biodiverse region among the most vulnerable to global change. In the first part of the PhD thesis, I investigated the short-term effects of climate change, human disturbance and biotic interactions on plant establishment dynamics at the local scale. In the first study, we performed a semi-field experiment, where we disturbed the soil and manipulated drought, nitrogen fertilization and arthropod herbivory. Plant establishment was modulated by the combined action of biotic and abiotic factors such as timing of soil disturbance and herbivory that are usually overlooked drivers. Results from this experiment stressed the need to incorporate herbivory effects and to adopt a multiple factor approach in global change studies. In the second study, I addressed similar questions by replicating the experiment under natural conditions in the European Alps along elevational gradients. Results from this field experiment highlighted the important role of arthropod herbivores, showing that natural herbivory might amplify soil disturbance negative effects on resident native species and favour exotics. Along the same elevational gradients, in the third study, I investigated what drives abundance and diversity of two key guilds of herbivorous insects with contrasting life-history traits. Thermophilic species such as grasshoppers will likely benefit from climate warming, while more specialised species such as leafhoppers are under threat by land-use change. With this study, I stressed that species will respond differently to global change based on their ecological strategy. In the second part of the PhD thesis, I explored the long-term effects of climate change and land-use on population and range dynamics of native and exotic species at the regional scale. In the fourth study, I compared the response to global change of extinct, threatened and exotic plants. Exotic plants are spreading quickly from anthropized valleys to alpine areas, while threatened species are contracting their range. The highest concentration of extinct, threatened and exotic plants was found in the lowlands, where human pressure is at its highest and protection at its minimum. In the lowlands, exotic species might displace threatened plants with low competition ability. In conclusion, I stressed the urgent need to mitigate habitat deterioration and loss in the lowlands, thereby enabling the survival of threatened populations. Finally, in the fifth study, I analysed demographic trends and range dynamics over 28 years for about two thirds of alpine orchid species. Abundance of most populations has declined and orchids were often unable to respond to climate warming and did not move from degraded and fragmented habitats. Results suggest that climate change was not the only factor threatening orchid persistence, but that the interaction between climate change and land use change drove orchid declines. In conclusion, three main messages emerged from these five studies. First, we should adopt a multiple factor approach when investigating global change impacts on species distribution. Most current research focuses on climate change impact, while a scenario where climate change is the only driver is highly unrealistic. Second, a better integration of multiple drivers should also incorporate the effects of biotic interactions. Here, I could stress the important role played by arthropod herbivores, but I could not integrate biotic interactions in long-term studies and many questions remain open. Finally, I advocate that considering species life-history traits should improve predictions of global change responses

Temperature and not landscape composition shapes wild bee communities in an urban environment

More than half of the world's population lives in urban areas, a proportion that is expected to increase. Even if urbanisation is widely regarded as a major threat to global biodiversity, recent research highlighted the potential ecological importance of cities for pollinators. Key determinants of cities' ability to sustain pollinators are the presence of green areas and the connectivity between them. However, also temperature is expected to be of primary importance for pollinator activities. Here, we aimed at disentangling the effects of temperature, open habitat cover, and distance from the city centre on wild bee communities in the city of Rome (Italy). We selected 36 sites along two statistically independent gradients of temperature and open habitat cover, and we sampled wild bee communities using pan-traps for 4 months. Then, we measured functional traits of wild bee species, that is, body size, social behaviour, nesting strategy, and diet breadth. Temperature emerged as the main driver of wild bee communities, with communities richer in species and individuals at warmer temperatures. We found little species replacement between cold and warm sites. In addition, with increasing temperatures, bee communities were dominated by polylectic and small-bodied species. Here, we showed that in a highly urbanised environment, temperature shapes pollinator communities irrespective of other landscape metrics. Even if warming seemed beneficial for urban pollinator abundance and richness, it might strongly homogenise bee communities by selecting for those traits that make species more easily adaptable

Consistent population declines but idiosyncratic range shifts in Alpine orchids under global change

Mountains are plant biodiversity hotspots considered particularly vulnerable to multiple environmental changes. Here, we quantify population changes and range-shift dynamics along elevational gradients over the last three decades for c. two-thirds of the orchid species of the European Alps. Local extinctions were more likely for small populations, after habitat alteration, and predominated at the rear edge of species’ ranges. Except for the most thermophilic species and wetland specialists, population density decreased over time. Declines were more pronounced for rear-edge populations, possibly due to multiple pressures such as climate warming, habitat alteration, and mismatched ecological interactions. Besides these demographic trends, different species exhibited idiosyncratic range shifts with more than 50% of the species lagging behind climate warming. Our study highlights the importance of long-term monitoring of populations and range distributions at fine spatial resolution to be able to fully understand the consequences of global change for orchids.The research was supported by the University of Padua STARS Consolidator Grant (STARS‐CoG–2017) to L.M. (BICE project)

Contrasting response of native and non‐native plants to disturbance and herbivory in mountain environments

Aim: Climate warming and increasing human disturbance are expected to promote non-native plant invasions in mountain ecosystems. Although biological invasions are also expected to be modulated by biotic interactions, it is still not clear how invertebrate herbivores can affect plant invasion dynamics. Using a large manipulative experiment, we aimed at testing: 1) the effect of soil disturbance and elevation on native and non-native plant communities, and 2) the effect of plant-herbivore interactions, nitrogen deposition, and elevation in driving plant establishment after soil disturbance. Location: European Alps, NE Italy Taxon: Vascular plants Methods: We selected remote, uninvaded dry semi-natural grasslands along the core elevational range of non-native plants in the European Alps (0-1330 m) and manipulated soil disturbance, nitrogen deposition, and invertebrate herbivory. Then, we followed the natural establishment under real field conditions of both native and non-native plants over one growing season. We used generalized mixed-effects models to test the effects of the experimental treatments. Results: Native and non-native species showed contrasting responses to soil disturbance and elevation. Low elevations and disturbance promoted non-native success, while affecting native species diversity negatively. Two-thirds of the experimental sites acquired novel non-natives after disturbance. Most of the observed non-natives were not present in the surrounding vegetation as mature plants, indicating that propagules were able to reach even remote natural areas. While current N deposition levels did not affect plant establishment, we found that after disturbance invertebrate herbivory might play an important role in facilitating non-native invasions by reducing native cover. Main conclusions: Our findings show that highly resistant ecosystems such as continuous grasslands can be easily invaded once the resident vegetation has been removed, and that natural herbivory pressure from invertebrates might amplify the negative effects of disturbance on resident native species irrespective of elevation. Together, these results indicate increasing risks of future plant invasions on mountains under global change

Both organic farming and flower strips support biodiversity, but organic farming is more profitable at field scale

Agri-environment schemes (AES) have been introduced to counteract the negative environmental effects caused by increased agricultural intensification in Europe (1). AES approaches can be also classified according to whether they prescribe management in non-productive areas, such as field boundaries and wildflower strips, or in productive areas, such as arable crops or grasslands. Here we test the ecological and economic effectiveness of the two most popular AESs in Lower Saxony, Germany: wildflower strips next to winter wheat fields as off-field practice and organic farming on winter wheat fields as on-field practice. For doing this we selected ten landscapes along a field size gradient with three wheat fields, one conventional field with flower strip, one organic field and one conventional field without flower strip as a common control (the two conventional fields were owned by the same farmer per landscape). During two consecutive years we surveyed plants in field margins, field edges and field interiors; we sampled carabids, spiders and rove beetle by pitfall traps in field edges and field interiors; we sampled bees and hoverflies by transect walks and sweepnetting in field margins. Additionally, we performed detailed economic interviews with our organic and conventional farmers to get revenue, cost and profit data per study field. Plants benefitted far the most from organic farming, whereas flowering strips had only a positive effect on plant richness in field margins, but no effect in the fields compared to the control. As expected due to the high flower cover, flower strips supported three times more bee species and only about 25% more hoverfly species than organic farming, with both AESs being more effective than the control. Finally, both AESs supported equally well carabids and spiders with about 20-30% higher species numbers than the control with exception of rove beetles, which rather avoided fields with flower strips in contrast to control and organic fields. Field size showed only a slight negative trend on the biodiversity of study taxa probably owning to the relatively short gradient in the small-scale agroecosystem of the study area (see also 2). Economic analyses showed the highest costs in control conventional fields and the highest revenues in organic fields leading to more than two times higher profit in the latter one, whereas fields with flower strips compromised a bit lower profit than the control. Wheat yield was about 90% higher in both types of conventional fields than in organic fields. In summary, both AES support farmland biodiversity depending on the taxonomic group at the field scale. The next question is how the effectiveness changes, when scaling up to farm scale or higher scale, or correcting for yield loss between the two AES. References (1) Batáry et al. 2015. Conserv. Biol. 29: 1006‒1016. (2) Batáry et al. 2017. Nature Ecol. Evol. 1: 1279‒1284.peerReviewe