Evaluating plant lineage losses and gains in temperate forest understories: a phylogenetic perspective on climate change and nitrogen deposition.

Global change has accelerated local species extinctions and colonizations, often resulting in losses and gains of evolutionary lineages with unique features. Do these losses and gains occur randomly across the phylogeny? We quantified: temporal changes in plant phylogenetic diversity (PD); and the phylogenetic relatedness (PR) of lost and gained species in 2672 semi-permanent vegetation plots in European temperate forest understories resurveyed over an average period of 40 yr. Controlling for differences in species richness, PD increased slightly over time and across plots. Moreover, lost species within plots exhibited a higher degree of PR than gained species. This implies that gained species originated from a more diverse set of evolutionary lineages than lost species. Certain lineages also lost and gained more species than expected by chance, with Ericaceae, Fabaceae, and Orchidaceae experiencing losses and Amaranthaceae, Cyperaceae, and Rosaceae showing gains. Species losses and gains displayed no significant phylogenetic signal in response to changes in macroclimatic conditions and nitrogen deposition. As anthropogenic global change intensifies, temperate forest understories experience losses and gains in specific phylogenetic branches and ecological strategies, while the overall mean PD remains relatively stable.

Les changements globaux accélèrent les processus de colonisation et d'extinction locales d'espèces, aboutissant à des gains ou à des pertes de lignées évolutives uniques. Ces gains et pertes se produisent-ils de manière aléatoire dans l'arbre phylogénétique ? Nous avons mesuré: les changements de diversité phylogénétique; et la parenté phylogénétique des espèces végétales gagnées ou perdues dans 2672 placettes semi-permanentes disposées dans le sous-bois de forêts tempérées d'Europe sur une période moyenne de 40 ans. Une fois corrigée par la richesse spécifique, la diversité phylogénétique a légèrement augmenté au cours du temps dans les différentes placettes. Les espèces perdues ont une plus grande parenté phylogénétique que les espèces gagnées. Les espèces gagnées sont donc issues d'un plus grand nombre de lignées évolutives que les espèces perdues. Certaines lignées ont gagné ou perdu davantage d'espèces que ce qui est prédit par le hasard : les Ericaceae, les Fabaceae et les Orchidaceae ayant davantage perdu, tandis que les Amaranthaceae, les Cyperaceae, et les Rosaceae ont plus gagné. Il n'y a pas de signal phylogénétique des gains ou pertes d'espèces en réponse aux changements de conditions macroclimatiques ou des dépôts atmosphériques d'azote. Alors que les changements globaux d'origine anthropique s'intensifient, les sous-bois des forêts tempérées connaissent des gains et des pertes de certaines lignées évolutives et de certaines stratégies écologiques, sans que la diversité phylogénétique moyenne ne s'en trouve véritablement affectée.

El cambio global ha acelerado las extinciones y colonizaciones a escala local, lo que a menudo ha supuesto pérdidas y ganancias de linajes evolutivos con características únicas. Ahora bien, ¿estas pérdidas y ganancias ocurren aleatoriamente a lo largo de la filogenia? Cuantificamos: los cambios temporales en la diversidad filogenética de las plantas; y la relación filogenética de las especies perdidas y ganadas en 2.672 parcelas de vegetación semipermanente en sotobosques templados europeos y re-muestreadas durante un período promedio de 40 años. Al controlar por las diferencias en la riqueza de especies, la diversidad filogenética aumentó ligeramente con el tiempo y entre parcelas. Además, las especies perdidas dentro de las parcelas exhibieron un mayor grado de relación filogenética que las especies ganadas. Esto implica que las especies ganadas se originaron en un conjunto de linajes evolutivos más diversos que las especies perdidas. Ciertos linajes también perdieron y ganaron más especies de las esperadas aleatoriamente: Ericaceae, Fabaceae y Orchidaceae experimentaron pérdidas y Amaranthaceae, Cyperaceae y Rosaceae mostraron ganancias. Las pérdidas y ganancias de especies no mostraron ninguna señal filogenética significativa en respuesta a los cambios en las condiciones macro-climáticas y la deposición de nitrógeno. A medida que se intensifica el cambio global antropogénico, los sotobosques temperados experimentan pérdidas y ganancias en ramas filogenéticas y estrategias ecológicas específicas, mientras que la diversidad filogenética media general permanece relativamente estable.

Scale dependency of taxonomic and functional diversity in pristine and recovered loess steppic grasslands.

Widespread campaigns on forest restoration and various tree planting actions lower the awareness of the importance of grasslands for carbon sequestration and biodiversity conservation. Even lower attention is given to the conservation of biodiversity and ecosystem functioning in remnants of ancient, so-called pristine grasslands. Pristine grasslands generally harbour high biodiversity, and even small patches can act as important refuges for many plant and animal species in urbanised or agricultural landscapes. Spontaneous succession of grassland is frequently viewed as a cost-effective tool for grassland restoration, but its applicability is strongly dependent on many local to landscape-scale factors, and the recovery is often slow. It is therefore essential to monitor the success of grassland restoration projects that rely on spontaneous succession. We compared the species diversity and functional attributes of pristine and recovered grasslands by studying the taxonomic and functional diversity in thirteen (8 pristine and 5 recovered) loess steppic grasslands using differently sized sampling plots from 0.01 to 100 m2. Our results indicate that there are remarkable differences in taxonomic and functional diversity between pristine and recovered grasslands. We also found that during secondary succession there is a likely functional saturation of the species assembly in the first few decades of recovery, and while patterns and structure of recovered grasslands became quite similar to those of pristine grasslands, species richness and diversity still remained much lower. Pristine grasslands support considerable plant diversity, and species composition is slow to recover if destroyed by agricultural land use. This underlines the importance of preserving existing pristine grassland remnants, which might serve as sources of species for future restoration measures.

Long-term nitrogen deposition reduces the diversity of nitrogen-fixing plants.

Biological nitrogen fixation is a fundamental part of ecosystem functioning. Anthropogenic nitrogen deposition and climate change may, however, limit the competitive advantage of nitrogen-fixing plants, leading to reduced relative diversity of nitrogen-fixing plants. Yet, assessments of changes of nitrogen-fixing plant long-term community diversity are rare. Here, we examine temporal trends in the diversity of nitrogen-fixing plants and their relationships with anthropogenic nitrogen deposition while accounting for changes in temperature and aridity. We used forest-floor vegetation resurveys of temperate forests in Europe and the United States spanning multiple decades. Nitrogen-fixer richness declined as nitrogen deposition increased over time but did not respond to changes in climate. Phylogenetic diversity also declined, as distinct lineages of N-fixers were lost between surveys, but the "winners" and "losers" among nitrogen-fixing lineages varied among study sites, suggesting that losses are context dependent. Anthropogenic nitrogen deposition reduces nitrogen-fixing plant diversity in ways that may strongly affect natural nitrogen fixation.

Unexpected westward range shifts in European forest plants link to nitrogen deposition.

Climate change is commonly assumed to induce species' range shifts toward the poles. Yet, other environmental changes may affect the geographical distribution of species in unexpected ways. Here, we quantify multidecadal shifts in the distribution of European forest plants and link these shifts to key drivers of forest biodiversity change: climate change, atmospheric deposition (nitrogen and sulfur), and forest canopy dynamics. Surprisingly, westward distribution shifts were 2.6 times more likely than northward ones. Not climate change, but nitrogen-mediated colonization events, possibly facilitated by the recovery from past acidifying deposition, best explain westward movements. Biodiversity redistribution patterns appear complex and are more likely driven by the interplay among several environmental changes than due to the exclusive effects of climate change alone.

New thousand-seed weight dataset for plant species of Central Europe.

One of the most important and most easily measurable physical characteristics of plant seeds is their weight, which influences and indicates crucial ecological processes. Seed weight affects spatial and temporal dispersibility, and can also influence seed predation and the germination, growth and survival of seedlings. Providing trait data for species missing from international databases is key to promote studies that advance our understanding of the functioning of plant communities and ecosystems, which is an essential issue in the face of the global climate change and biodiversity loss. Compared to species from Western and Northwestern Europe, those with an Eastern or Central European centre of distribution are underrepresented in most international trait databases. Therefore, the creation of specific trait databases is key to help regional studies. In this respect, it is important not only to collect fresh seeds for weight measurements, but also to measure and process data of seeds preserved in collections and make them available to the broader scientific community. In this data paper we provide seed weight data to fill in missing trait data of plant species of Central and Eastern Europe. Our dataset includes weight measurement for 281 taxa of the Central European flora including also some cultivated and exotic species. The seeds were collected between 1971 and 2021 mostly in Central Europe. One part of the measured seeds was collected in the last decade, the other part is from an older seed collection, but all seeds were measured recently. For each species, we collected a minimum of 3 × 100 intact seeds, if possible. The seeds were air-dried at room temperature (approximately 21 °C and 50% relative humidity) for at least two weeks and measured with an accuracy of 0.001 g using an analytical balance. The thousand-seed weights reported here were calculated based on the measured values. Our goal for the future is to incorporate the seed weight data reported here in a regional database (Pannonian Database of Plant Traits - PADAPT) that gathers plant traits and other plant characteristics for the Pannonian flora. The data presented here will facilitate trait-based analyses of the flora and vegetation of Central Europe.

New data of plant leaf traits from Central Europe.

Trait-based ecology is gaining ground nowadays on species-based ecology: the number of research and publication focusing on the ecological role of taxa instead of the species themselves increased significantly in the last two decades. One great advantage of this approach is that communities with different species composition due to great geographical distances (e.g., different continents) or different environmental conditions (e.g., loess, sand, and alkaline grasslands) become comparable. Obtaining trait values is, however, labour and time consuming even in the case of so-called soft traits. It is therefore reasonable and desirable for scientists to share their data as widely as possible. Demand for such data induced the publication of data papers and the establishment of databases, which support both theoretical ecological research and practical restoration ecological projects. Although several international databases (e.g., TRY, LEDA, CLO-PLA, BiolFLOR) are available nowadays, Central and Eastern European species are either missing or underrepresented in them. Consequently, measurement and publication of the traits of species typical in the above region is necessary. This paper presents leaf trait (leaf fresh and dry weight, leaf area, specific leaf area and leaf dry matter content) data for more than 1100 species of the Central European flora.

Divergent roles of herbivory in eutrophying forests.

Ungulate populations are increasing across Europe with important implications for forest plant communities. Concurrently, atmospheric nitrogen (N) deposition continues to eutrophicate forests, threatening many rare, often more nutrient-efficient, plant species. These pressures may critically interact to shape biodiversity as in grassland and tundra systems, yet any potential interactions in forests remain poorly understood. Here, we combined vegetation resurveys from 52 sites across 13 European countries to test how changes in ungulate herbivory and eutrophication drive long-term changes in forest understorey communities. Increases in herbivory were associated with elevated temporal species turnover, however, identities of winner and loser species depended on N levels. Under low levels of N-deposition, herbivory favored threatened and small-ranged species while reducing the proportion of non-native and nutrient-demanding species. Yet all these trends were reversed under high levels of N-deposition. Herbivores also reduced shrub cover, likely exacerbating N effects by increasing light levels in the understorey. Eutrophication levels may therefore determine whether herbivory acts as a catalyst for the "N time bomb" or as a conservation tool in temperate forests.

Response to Comment on "Forest microclimate dynamics drive plant responses to warming".

Bertrand et al question our interpretation about warming effects on the thermophilization in forest plant communities and propose an alternative way to analyze climatic debt. We show that microclimate warming is a better predictor than macroclimate warming for studying forest plant community responses to warming. Their additional analyses do not affect or change our interpretations and conclusions.

Response to Comment on "Forest microclimate dynamics drive plant responses to warming".

Schall and Heinrichs question our interpretation that the climatic debt in understory plant communities is locally modulated by canopy buffering. However, our results clearly show that the discrepancy between microclimate warming rates and thermophilization rates is highest in forests where canopy cover was reduced, which suggests that the need for communities to respond to warming is highest in those forests.

Forest microclimate dynamics drive plant responses to warming.

Climate warming is causing a shift in biological communities in favor of warm-affinity species (i.e., thermophilization). Species responses often lag behind climate warming, but the reasons for such lags remain largely unknown. Here, we analyzed multidecadal understory microclimate dynamics in European forests and show that thermophilization and the climatic lag in forest plant communities are primarily controlled by microclimate. Increasing tree canopy cover reduces warming rates inside forests, but loss of canopy cover leads to increased local heat that exacerbates the disequilibrium between community responses and climate change. Reciprocal effects between plants and microclimates are key to understanding the response of forest biodiversity and functioning to climate and land-use changes.

Replacements of small- by large-ranged species scale up to diversity loss in Europe's temperate forest biome.

Biodiversity time series reveal global losses and accelerated redistributions of species, but no net loss in local species richness. To better understand how these patterns are linked, we quantify how individual species trajectories scale up to diversity changes using data from 68 vegetation resurvey studies of seminatural forests in Europe. Herb-layer species with small geographic ranges are being replaced by more widely distributed species, and our results suggest that this is due less to species abundances than to species nitrogen niches. Nitrogen deposition accelerates the extinctions of small-ranged, nitrogen-efficient plants and colonization by broadly distributed, nitrogen-demanding plants (including non-natives). Despite no net change in species richness at the spatial scale of a study site, the losses of small-ranged species reduce biome-scale (gamma) diversity. These results provide one mechanism to explain the directional replacement of small-ranged species within sites and thus explain patterns of biodiversity change across spatial scales.

[Limb salvage by excision of calcaneus in diabetic atherosclerotic gangrene]. / Végtagmegtartás diabeteszes, arterioscleroticus gangrénában a sarokcsont kiirtásával.

We treated a 49-year-old female patient, who developed diabetic, arteriosclerotic gangrene. Only after the extensive wet gangrene extended to the proximal half sole, she was finally consenting to surgery, and a femoropopliteal Dacron bypass graft was performed. The area of the osteomyelitic calcaneus was removed by necrectomy (slough cutting) but the calcaneus fractured spontaneously after two weeks. Therefore the calcaneus was excised and the half-sole defect was covered by the available skin of the posterior heel and forefoot region. The wound required meticulous local treatment for two months. She has been able to walk without a frame using an orthopedic shoe fitted with a total contact insole with proper lifting of the heel region. Our aim was limb saving and recovery favourable to crural amputation, which could have been justified in such extensive gangrene. We would like to highlight to the possibility of the excision of the calcaneus, as no data has been found about it in the Hungarian literature. Walking after the excision of the calcaneus is possible with the help of a specially developed orthopaedic shoe, properly fitted with a total contact insole.