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Aims We examined the importance of litter quality and microclimate on early-stage litter mass loss, analysed the importance of interactions among environmental factors in determining key decomposition parameters and compared the variation in decomposition rates in vegetation types and sites with similar climate. Methods Following the Tea-Bag Index approach, 464 tea-bags were incubated in the soil in 79 sites, distributed across Italy, which included six vegetation types and a broad range of microclimatic conditions. Results Litter type exerted a stronger control on mass loss compared to climatic factors. The effects of soil moisture were not the same for high and lower quality litter. In addition, the effects of temperature on the decomposition rate depended on soil moisture. The stabilization factor was strongly temperature-dependent, but the influence of temperature differed among vegetation types: those dominated by small-size plants showed a strong decrease in the potential amount of plant material entering into the soil stock under warmer temperatures. The lowest variation in decomposition rate was found in sites characterised by low temperatures, and, among the vegetation types, in alpine snowbeds. Conclusions The role of litter quality and of the interactions among environmental conditions can potentially determine significant shifts in the expected patterns of ecosystem carbon fluxes.

The use of wood distillate (WD) is emerging as a valuable strategy for protecting horticultural crops from the oxidizing effects of ozone (O3). To fully understand its effectiveness, extensive testing on different plant species is needed. As a viable interim measure, an assessment of WD efficacy in model plants can be made until species-specific results become available. The aim of this study is to evaluate the ability of WD to protect the ozone-sensitive tobacco plant (Nicotiana tabacum L.) BelW3 from the oxidizing effects of O3, using the ozone-resistant tobacco plant BelB as a benchmark. The protective effect was evaluated during treatment applications and three weeks after these were completed. Ten BelW3 and five BelB plants were grown just outside Parma from June to October 2023, a period when average maximum O3 concentrations were approximately 61 ppb. Starting from July, five BelW3 plants were sprayed weekly with WD at 0.2% for two months. Morphometric and photosynthetic measurements were then taken after six and 11 weeks from the beginning of treatments and three weeks after the end to assess protection persistence (if any). BelW3 showed a significant effect of O3 compared to BelB plants for both morphometric and photosynthetic measurements, exhibiting increased necrotic areas on the leaf blade, reduced number of viable leaves, reduced average plant height, together with reduced chlorophyll content and impaired photosynthetic system functionality. BelW3 plants also showed a significant decrease in the efficiency of parameters related to PSII and PSI when compared to BelB. Wood distillate application, however, successfully mitigated O3 effects on BelW3, as revealed by morphometric and photosynthetic values, which were in line with those observed in BelB. Notably, WD protective effect persisted 3 weeks after treatment cessation, highlighting the short-term protective capacity of the distillate against the oxidative action of O3.

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Alpine snowbed communities are among the habitats most threatened by climate change. The warmer temperature predicted, coupled with advanced snowmelt time, will influence flowering phenology, which is a key process in species adaptation to changing environmental conditions and plant population dynamics. However, we know little about the effects of changing micro-climate on flowering time in snowbeds and the mechanisms underlying such phenological responses. The flowering phenology of species inhabiting alpine snowbeds was assessed with weekly observations over five growing seasons. We analysed flowering time in relation to micro-climatic variation in snowmelt date, soil and air temperature, and experimental warming during the snow-free period. This approach allowed us to test hypotheses concerning the processes driving flowering phenology. The plants were finely tuned with inter-annual and intra-seasonal variations of their micro-climate, but species did not track the same micro-climatic feature to flower. At the growing-season time-scale, the air surrounding the plants was the most common trigger of the blooming period. However, at the annual time-scale, the snowmelt date was the main controlling factor for flowering time, even in warmer climate. Moreover, spatial patterns of the snowmelt influenced the developmental rate of the species because in later snowmelt sites the plants needed a lower level of heat accumulation to enter anthesis. Phenological responses to experimental warming differed among species, were proportional to the pre-flowering time-span of plants, and did not show consistent trends of change over time. Finally, warmer temperature produced an overall increase of flowering synchrony both within and among plant species.

In ecological theory, it is currently unclear if intraspecific trait responses to environmental variation are shared across plant species. We use one of the strongest environmental variations in alpine ecosystems, i.e., advanced snowmelt due to climate warming, to answer this question for alpine snowbed plants. Snowbeds are extreme habitats where long-lasting snow cover represents the key environmental factor affecting plant life. Intraspecific variation in plant functional traits is a key to understanding the performance and vulnerability of species in a rapidly changing environment. We sampled snowbed species after an above-average warm winter to assess their phenotypic adjustment to advanced snowmelt, based on differences in the natural snowmelt dynamics with magnitudes reflecting predicted future warming. We measured nine functional traits related to plant growth and reproduction in seven vascular species, comparing snowbeds of early and late snowmelt across four snowbed sites in the southern Alps in Italy. The early snowbeds provide a proxy for the advanced snowmelt caused by climatic warming. Seed production was reduced under advanced snowmelt in all seed-forming snowbed species. Higher specific leaf area (SLA) and lower leaf dry matter content (LDMC) were indicative of improved growth potential in most seed-forming species under advanced snowmelt. We conclude, first, that in the short term, advanced snowmelt can improve snowbed species' growth potential. However, in the long term, results from other studies hint at increasing competition in case of ongoing improvement of conditions for plant growth under continued future climate warming, representing a risk for snowbed species. Second, a lower seed production can negatively affect the seed rain. A reduction of propagule pressure can be crucial in a context of loss of the present snowbed sites and the formation of new ones at higher altitudes along with climate warming. Finally, our findings encourage using plant functional traits at the intraspecific level across species as a tool to understand the future ecological challenges of plants in changing environments.

This study aimed to assess the impact of different biochar (BCH) applications (0%, 10%, 20%, and 50%, v/v) on soil respiration in a European beech (Fagus sylvatica L.) forest located in the Tuscan-Emilian Apennines. The experiment was conducted over four months during summer 2023. Results revealed that BCH applications did not significantly affect overall soil respiration. On the other hand, soil respiration was positively influenced by soil temperature and soil moisture, the latter only for the 10% and 20% BCH amendments. At higher BCH concentrations (50%), soil respiration was not enhanced by moisture, probably due to soil water saturation and reduced oxygen availability. In conclusion, it appears that BCH does not directly stimulate soil respiration in field conditions, although specific concentrations may improve soil carbon sequestration. These findings highlight the potential for BCH amendments to be employed as a climate-smart forestry strategy in support of carbon sequestration and ecosystem stability in temperate forest ecosystems.

The International Tundra Experiment (ITEX) was founded in 1990 as a network of scientists studying responses of tundra ecosystems to ambient and experimental climate change at Arctic and alpine sites across the globe. Common measurement and experimental design protocols have facilitated synthesis of results across sites to gain biome-wide insights of climate change impacts on tundra. This special issue presents results from more than 30 years of ITEX research. The importance of snow regimes, bryophytes, and herbivory are highlighted, with new protocols and studies proposed. The increasing frequency and magnitude of extreme climate events is shown to have strong effects on plant reproduction. The most consistent plant trait response across sites is an increase in vegetation height, especially for shrubs. This will affect surface energy balance, carbon and nutrient dynamics and trophic level interactions. Common garden studies show adaptation responses in tundra species to climate change but they are species and regionally specific. Recommendations are made including establishing sites near northern communities to increase reciprocal engagement with local knowledge holders and establishing multi-factor experiments. The success of ITEX is based on collegial cooperation among researchers and the network remains focused on documenting and understanding impacts of environmental change on tundra ecosystems.

In snowbed habitats, characterized by a long-lasting snow cover, the timing of snowmelt can be included among the major factors controlling plant phenology. Nevertheless, only a few ecological studies have tested the responses of flowering phenology of species growing in very late snow-free habitats to an advanced snowmelt (AS) date. The aim of this study was to determine the impacts of an extremely earlier melt-out of snow on flowering phenology of vascular plant species inhabiting an alpine snowbed. The study was conducted in the high Gavia Valley (Italy, 2,700 m a.s.l.). On 30th May 2012, we removed manually the snow cover and set up an experiment with 5 AS and 5 control plots. Phenological observations of the most abundant vascular species were conducted every 4–6 days. Moreover, we calculated cumulative soil temperature and recorded the mortality of reproductive structures of three species. For several species flowering occurred earlier, and the prefloration period was extended in the AS treatment in comparison with the control. For the majority of species, cumulative soil temperatures in the AS treatment and the control were comparable, confirming that temperature exerts the main control on the flowering of the species inhabiting snowbeds. Earlier flowering species resulted more affected by an AS date in comparison with later flowering species. The mortality of reproductive structures did not increase in the AS treatments in comparison with the control suggesting that few and weak frost events in late spring do not affect the survival of reproductive structures of the species studied.

Biochar (BC) boasts diverse environmental applications. However, its potential for environmental biomonitoring has, surprisingly, remained largely unexplored. This study presents a preliminary analysis of BC’s potential as a biomonitor for the environmental availability of ionic Cd, utilizing the lichen Evernia prunastri (L.) Ach. as a reference organism. For this purpose, the lichen E. prunastri and two types of wood-derived biochar, biochar 1 (BC1) and biochar 2 (BC2), obtained from two anonymous producers, were investigated for their ability to accumulate, or sequester and subsequently release, Cd when exposed to Cd-depleted conditions. Samples of lichen and biochar (fractions between 2 and 4 mm) were soaked for 1 h in a solution containing deionized water (control), 10 µM, and 100 µM Cd2+ (accumulation phase). Then, 50% of the treated samples were soaked for 24 h in deionized water (depuration phase). The lichen showed a very good ability to adsorb ionic Cd, higher than the two biochar samples (more than 46.5%), and a weak ability to release the metal (ca. 6%). As compared to the lichen, BC2 showed a lower capacity for Cd accumulation (−48%) and release (ca. 3%). BC1, on the other hand, showed a slightly higher Cd accumulation capacity than BC2 (+3.6%), but a release capacity similar to that of the lichen (ca. 5%). The surface area and the cation exchange capacity of the organism and the tested materials seem to play a key role in their ability to accumulate and sequester Cd, respectively. This study suggests the potential use of BC as a (bio)monitor for the presence of PTEs in atmospheric depositions and, perhaps, water bodies.

Biochar (BC) soil amendments could partially counteract soil carbon (C) stock decrease in broad-leaved forests in Italy; however, its effects on the growth of representative tree species—Fagus sylvatica L. and Quercus cerris L.—has not yet been addressed. We examine whether seed germination and growth of these species are affected by addition of BC obtained from deciduous broadleaf trees. Seeds were left to germinate in greenhouse conditions under three different BC amendments: 0% (control), 10% and 20% (v/v). Seedlings were then subjected to controlled conditions under the same BC percentage. Biochar effects on seed germination were assessed measuring germination time and percentage, while effects on photosynthesis were assessed using leaf chlorophyll content (mg/m2) and photosynthetic efficiency (FV/FM). Plant growth was estimated by recording leaf number, longest leaf length and plant height. Biochar treatments had no negative effects on germination and early growth stage of the two species. Positive effects were found on the chlorophyll content of both species (ca. +8%) regardless of the treatment and on the leaf number (+30%), leaf length (+14%) and plant height (+48%) of Q. cerris (only with 10% BC). Biochar applications seem, therefore, a suitable method for increasing broad-leaved forest C stock in Italy.