Mediterranean-type Climate Research Articles

Short-term soil fungal community dynamics following fire in mediterranean climate-type banksia woodlands

Fire is a dominant ecosystem process in many Mediterranean climate type ecosystems, and is predicted to increase in severity and frequency, shifting away from previous regimes in many regions. Responses of flora and fauna to fire are relatively well studied, but less is known about the responses of belowground microbiota. We quantified soil fungal dynamics over the first 12–15 months after fire, focusing on attributes of the fire regime (season, interval, severity). Soil samples were collected from three sites in a threatened woodland ecosystem in southwestern Australia, a Mediterranean-type climate region. Fungal taxa were identified via high throughput sequencing of the ITS subregion and taxonomy assigned using reference databases. Richness, diversity, abundance, community composition, and functional groups were quantified. Over the post-fire sampling period, richness and diversity declined and soil fungal community composition changed significantly throughout the sampling period, with family level taxa and functional groupings experiencing the most change. Through the sampling period, an increase in saprotrophic and endophytic fungi was observed, along with a decrease in all pathogenic fungi. We found that the post-fire fungal community is quite dynamic in the first 12–15 months after fire. We found little effect of fire interval or fire season, though our inference was limited. Our work contributes to putting belowground biota into the same conceptual frameworks as aboveground taxa and serves to inform fire managers in fire-prone Mediterranean climate type regions.

Early Growth and Physiological Acclimation to Shade and Water Restriction of Seven Sclerophyllous Species of the Mediterranean Forests of Central Chile.

The success of using active restoration in Mediterranean-type climate zones mostly depends on an appropriate matching of plant species and specific management prescriptions upon establishment. In this study, we assessed the early growth and short-term physiological acclimation of seven common species found in the sclerophyllous forests in central Chile to water restriction and shading. We established a nursery experiment that included three treatments (T0: sun-exposed and water-restricted, T1: sun-exposed and fully irrigated, and T2: shaded and fully irrigated) and seven tree species differing in their shade and drought tolerance (Quillaja saponaria Molina, Aristotelia chilensis (Mol.) Stuntz, Peumus boldus Molina, Lithraea caustica (Mol.) Hook. and Arn, Luma apiculata (DC.) Burret, Colliguaja odorifera Molina, and Escallonia pulverulenta (Ruiz and Prav.) Pers). We measured the increment in seedling height and different leaf morpho-physiological traits during two months in the dry season. Based on the measured traits, none of the species took advantage of the higher water availability in T1 relative to T0, but most of the species responded to the shade in T2, regardless of their shade or drought tolerance. Height increments due to shade varied from 0% in P. boldus to 203% in L. apiculata. Overall, all the species responded similarly to the treatments in specific leaf area, chlorophyll content index, photosynthetic rate, stomatal conductance, and intrinsic water use efficiency. This suggests that the species exhibited similar acclimation patterns of these parameters to shade and drought, even regarding the variation in midday xylem water potential found in the water-restricted treatment T0 (from -1.5 MPa in P. boldus to -3.1 MPa in E. pulverulenta). In this study, shading had a higher positive effect on the seedling performance of sclerophyllous species than watering, which at operational level highlights the need for investing in tree shelters when using these species in restoration programs.

Unveiling the Opportunities of Unexplored Use of Cover Crop in Mediterranean Agriculture through Systematic Review and Meta-Analysis

Cover crops are multifunctional, and contribute to improving soil properties and reducing environmental impact compared to no-cover crops, thus could provide multiple soil, agricultural, and environmental benefits, and they are recognized as a valid strategy for the achievement of sustainable agriculture. However, cover crops’ impacts on subsequent cash crops and soil characteristics are dependent on several factors, such as pedoclimatic conditions, cover crop species, agricultural practices, method of termination, and irrigation management. The fact that cover crops are never applied as a single practice in the real agricultural sector, but are instead combined with other factors or agricultural practices, deeply affects their performance, but the scientific literature nevertheless keeps considering the use of cover crops alone. Moreover, the potential outcomes of cover crops that encompass other factors or agricultural practices affecting soil quality, weed control, and cash crops are still unclear. Additionally, cover crops are still poorly use in the Mediterranean type of climate. Therefore, this study reviewed the scientific literature to identify the most relevant factors or agricultural practices driving cover crops’ performance, and to outline future fields of investigation looking towards promising sustainable agriculture in Mediterranean areas with a view to minimizing the competition for soil water with the cropping systems and to reduce soil degradation. Furthermore, the investigation includes multiple factors or agricultural practices that better represent the real farming system, contributing to a comprehensive understanding of their interactions with cover crops, and suggests alternative strategies for reducing yield gap while seeking to achieve agricultural sustainability.

Actinobacteria diversity associated with marine sediments and a wetland system, Agulhas-South Africa

BackgroundSouth Africa is known for its great biodiversity. The Agulhas Plain represents one such unique environment where low-gradient topography has resulted in extensive wetland formation. It is fed by two major river systems, bringing in brackish, alkaline water. It has been exposed to major marine transgression and regression events, and harbours great Fynbos diversity as well as a Mediterranean-type climate, thereby creating unique ecosystems. It is therefore surprising that little is known about the bacterial diversity associated with the Agulhas Plain and associated marine ecosystems.MethodsIn this study, we focused on the actinobacterial diversity (Phylum Actinomycetota) associated with an emerging peatland on the Agulhas Plain (SF; Areas 1–3) and a marine site (ANP; Ocean, Rocky, Dry) located 10 km away from SF. A combined metataxanomics and isolation approach was taken to evaluate the actinobacterial diversity of the sampling sites and to determine the effect of environmental physicochemical parameters on these populations. Various genome analyses were performed on an Sva0096 marine bin to gain insight into its ecological role.ResultsMetataxanomics showed that the two sites shared defined major taxa, including Blastococcus, Geodermatophilus, Microbacterium, Mycobacterium, Nocardioides, Streptomyces, and the Sva0996 marine group. Analysis of the biosynthetic potential of an Sva0996 marine bin134 (obtained from GenBank) provided insights into the potential ecological role of this group of bacteria in both the marine and terrestrial environments. Higher actinobacterial diversity (Shannon index > 5) was observed for Areas 2 and 3 (SF), as well as the ANP Dry samples. The actinobacterial population composition was found to be driven by salinity, pH, Mn, and Ca, with certain areas of SF exhibiting similar (and even higher) salinity (SF: 70–100 Ω vs. ANP: 100–160 Ω) and lower pH levels (SF: 6.3-8.0 vs. ANP: 8.6–8.9) to that of the marine environment.ConclusionThis snapshot study has provided some insights into the actinobacterial diversity of the two sites studied. Analysis of an Sva0096 marine bin134 provided further insights into the potential ability of the Sva0096 marine group to survive in a unique terrestrial environment that is periodically exposed to environmental pressures that mimic the marine environment.

Early development of Acacia longifolia is more severely impacted by water and nutrient stress in invasive than native seedlings

Acacia longifolia (Andrews) Willd. is a legume native to southeast mainland Australia and Tasmania and has two described subspecies: A. l. subsp. longifolia and A. l. subsp. sophorae. The species has been introduced around the world and is considered invasive in several Mediterranean-type climate regions, including in South America, South Africa, and southern Europe. Previous studies comparing native and invasive populations of A. longifolia have focused on its reproductive ecology and population genetics, and little information exists on the species’ early life development and how abiotic factors influence it. Here, we performed a glasshouse experiment to compare the phenotypic responses of native and invasive (in Portugal) A. longifolia seedlings to different levels of water and nutrient availability. We found that seedlings of both subspecies responded similarly to different water and nutrient availability conditions in terms of biomass accumulation, root length, the number of phyllodes produced, phyllode water content, and root-to-shoot ratio. However, compared to native seedlings, invasive seedlings had limited capacity for stress responses. We found that invasive seedlings had lower drought tolerance than native seedlings, and thus the speed of invasion by A. longifolia into drier parts of Portugal may be hindered. Our results also hint of a possible role of seed “imprinting” in this species’ early growth responses, resulting in different resource allocation strategies such as favouring early growth and development over drought resistance in the invaded range. Further studies are required to better understand the species’ abiotic stress responses at the intraspecific level and their relation to its invasiveness.

Surface urban heat island analysis based on local climate zones using ECOSTRESS and Landsat data: A case study of Valencia city (Spain)

Extreme heat events in cities are becoming more intense, frequent and prolonged. The spatiotemporal dynamics of surface temperature are closely related to land cover and atmospheric conditions, especially for urban areas with extensive surface heterogeneity. Two high spatial resolution satellites, ECOSTRESS and Landsat, provide land surface temperature (LST) for a typical Mediterranean climate city, Valencia, Spain. In total of 17 images throughout two heatwaves in the period of July and August from 2022 to 2023 were selected to monitor LST and surface urban heat island (SUHI). The Local Climate Zone (LCZ) scheme and hotspot analysis were applied to analyze the patterns of LST and SUHI during and after the heatwaves. Daytime images show LCZ 2/3/6/8 and LCZ C/E/F exhibit elevated SUHI intensity, meanwhile the LCZ 4, A/B and G have lower SUHI. The SUHI intensity of compact buildings (LCZ 1/2/3), LCZ 8/E/G are significantly higher at night, especially on heatwave days, the SUHI of all types increased by 0.1–0.9 °C. Furthermore, the meteorological parameters were introduced trying to explain the obvious diurnal difference of SUHI during heatwaves. This research serves as a proxy for understanding the spatiotemporal dynamics of SUHI during heatwave events, offering valuable insights for city planners and policymakers to enhance thermal comfortable level and effectively cope with extreme weather.

Experimental and numerical approach for the evaluation of PV-system performance on energy and environmental behavior of nearly zero energy buildings: Case study in Mediterranean climate

Nowadays, the performance of photovoltaic (PV) systems has strategic role for satisfying the standard of net or nearly zero energy building with in-situ production. In this frame, the novelty of the paper is the proposal of a combined experimental and numerical approach for evaluating the mismatch between PV production and consumptions during design, operational and future performance under expected emissions scenarios. First of all, it proposes a comparison of production estimation by means of several tools for the evaluation of the energy balance in the design phase; then the expected and real behavior is compared with also the evaluation of the performance ratio (PR) evolution as function of cell temperature. Finally, a sensitivity analysis is proposed in the short and medium scenarios by varying the size of installed system and considering the degradation rate under future weather conditions. The approach is applied to a case study in a typical Mediterranean climate, starting from the monitoring data available for the building energy request and the renewable production (2016–2022). The results of the case study indicate that the PR greatly influences the performance, mainly under expected climate changes, since the operational emissions could increase of more than 15 % compared to actual performance also if the zero energy balance is satisfied. Furthermore, through a sensitivity analysis on the PV-system size, the study demonstrates that with a maximum linear degradation rate of 1.51 %/year, the building could be configured as nearly zero energy in the medium term (20 years) also with lower peak power. The analysis also suggests that the maximization of installed power is a prerequisite to follow the implementation of positive energy goal because, under all considered climatic evolutions it can balance the penalties both due to technical aspects that to modification of consumption and production profiles.

Using remote sensing models to determine evapotranspiration of a pomegranate orchard in a Mediterranean-type climate

Using remote sensing models to determine evapotranspiration of a pomegranate orchard in a Mediterranean-type climate

Floristic diversity of vascular plants in the Mimouna Forest (north-western Algeria)

In arid and semi-arid areas, wild vegetation is a very important natural resource and provides various ecosystem services, such as environmental adjustment functions. It is therefore important to manage and protect plant diversity in these areas. We investigated the Mimouna Forest in the Algerian Saida Province, characterized by a Mediterranean-type climate with maximum average monthly temperature of 27.1°C, minimum of 8.3°C and annual rainfall of 345 mm. We described and analysed the species diversity of vascular plants in this area. The floristic inventory was carried out using a subjective sampling method. This allowed us to identify 93 species belonging to 80 genera and 33 botanical families. The major families were the Asteraceae (16%) and Poaceae (14%). The analysis of plant life-forms showed the dominance of therophytes (36%) and hemicryptophytes (28%). On the phytogeographic level, the prevailing chorological elements were of Mediterranean affinity (54% in total). Endemic taxa accounted for 9% of the flora. The Shannon index was moderately high (3.62) and 13% of the recorded species were rare, including 5 protected by Algerian law.

Multiscale analysis of a seasonal latent thermal energy storage with solar collectors for a single-family building

This paper presents a comprehensive system-to-CFD multiscale analysis of a seasonal thermal energy storage (STES) system based on phase change materials (PCMs) for efficient energy storage and release for space heating. The study investigates the impact of various factors, including the geometry of the individual storage tank and the thermo-fluid dynamic parameters of the heat transfer fluid on the system performance. The work focuses on STES integration with space heating system to meet the thermal energy demands of a typical single-family building located in Naples – South Italy, typical coastline Mediterranean climate. The primary goal is to assess the behaviour of the system-integrated PCM tank and its characteristic parameters, leading to the proposal of sustainable approaches that include renewable energy sources and partially fulfil the building thermal loads. Among the Scenarios, one stands out as it achieves a better operation, allowing storage and solar collectors to cover around 69.2 % of the winter heating demand, i.e., 3.06 MWh. The study also discusses the benefits of modular system operation, as evidenced by Scenario 3, which allows for the parallel discharge of multiple LHTES tanks, leading to an enhancement in efficiency compared to other Scenarios. Results indicate that the total energy discharged by a single STES is 56.30 kWh, with a latent heat fraction released over a time of 111 h and an average temperature difference of 5.65 °C. The tank efficiency reaches a value of 90.4 %, demonstrating the effectiveness of the STES system in meeting heating demands.

Seasonal impact of acid mine drainage on water quality and potential ecological risk in an old sulfide exploitation

Sulfides are usually associated with deposits of metals and coal. The reactive wastes from their exploitation, typically stored in piles and tailings dams, are often the mining sector’s primary source of environmental problems. The surrounding river waters can present signs of acid mine drainage, responsible for aquatic ecosystem degradation. So, the main target of the present study is to investigate the impact of this process on the water’s environmental quality and potential ecological risk. The study area is located at the Iberian Pyrite Belt, in an old sulfide exploitation, closed without environmental rehabilitation measures. The results exhibit high sulfate concentrations (410,601 mg/L) and potentially toxic elements, with prominence of Fe (134,000 mg/L), overcoming many other extreme cases of AMD pollution. The Ficklin diagram exposes that most samples are classified as “high-acid, high-metal.” Two of them have extreme classifications (high-acid, extreme-metal). The pH value is well below the acceptable range for the environmental quality of superficial waters (5–7), measuring at a minimum of 0.84. Regarding seasonal variability, the study showed a higher degree of contamination in dry conditions (e.g., 4,420 mg/L of Cu), while the rainy month had lower concentrations of PTE (186.8 mg/L of Cu for the same sampling point). In addition, the water does not accomplish the environmental objectives established by the EU Water Framework Directive. According to the new approach developed based on a scale adjustment, the potential ecological risk index studied indicates that most sampled sites present strong, very strong, and even extremely potential ecological risk. With a typical Mediterranean climate, the region suffers from water scarcity, predicting increasingly in the future more degrading scenarios for water environmental quality. Consequently, urgent mitigation and remediation measures are necessary to improve and preserve water quality and fulfill the objectives of the United Nations Sustainability Development Goals.

Adapting American Hop (Humulus lupulus L.) Varieties to Mediterranean Sustainable Agriculture: A Trellis Height Exploration

In recent years, Italy’s craft beer industry has seen remarkable growth, fostering the local production of key ingredients, notably hops. However, a research gap exists in exploring open-field hop productivity in typical Mediterranean climates using low-trellis systems. This study addressed this gap by evaluating the productive performances of “Cascade” and “Chinook” hop varieties on “V” trellis systems at different heights (2.60, 3.60, and 4.60 m above ground) in inner Sicily’s Mediterranean climate and soil conditions. The results highlighted the significant impact of trellis height on various parameters, with Cascade displaying exceptional adaptability to low-trellis farming. Key factors like stem and leaf weight emerged as crucial drivers of cone yield, emphasizing their significance in hop cultivation. The distinct responses of Cascade and Chinook varieties to varying trellis heights underscored the need for tailored approaches, offering valuable insights for optimizing hop cultivation practices in semi-arid climates.

Streptomyces spp. Strains as Potential Biological Control Agents against Verticillium Wilt of Olive.

Verticillium wilt of olive (VWO) caused by Verticillium dahliae is considered a major olive (Olea europaea) disease in Mediterranean-type climate regions. The lack of effective chemical products against VWO makes it necessary to search for alternatives such as biological control. The main goal of this study was to evaluate the effect of six Streptomyces spp. strains as biological control agents (BCAs) against VWO. All of them were molecularly characterized by sequencing 16S or 23S rRNA genes and via phylogenetic analysis. Their effect was evaluated in vitro on the mycelial growth of V. dahliae (isolates V004 and V323) and on microsclerotia (MS) viability using naturally infested soils. Bioassays in olive plants inoculated with V. dahliae were also conducted to evaluate their effect against disease progress. In all the experiments, the reference BCAs Fusarium oxysporum FO12 and Aureobasidium pullulans AP08 were included for comparative purposes. The six strains were identified as Streptomyces spp., and they were considered as potential new species. All the BCAs, including Streptomyces strains, showed a significant effect on mycelial growth inhibition for both V. dahliae isolates compared to the positive control, with FO12 being the most effective, followed by AP08, while the Streptomyces spp. strains showed an intermediate effect. All the BCAs tested also showed a significant effect on the inhibition of germination of V. dahliae MS compared to the untreated control, with FO12 being the most effective treatment. Irrigation treatments with Streptomyces strain CBQ-EBa-21 or FO12 were significantly more effective in reducing disease severity and disease progress in olive plants inoculated with V. dahliae compared to the remaining treatments. This study represents the first approach to elucidating the potential effect of Streptomyces strains against VWO.

Yield improvement with antitranspirant application in droughted wheat associated with both reduced transpiration and reduced abscisic acid

AbstractIn Mediterranean-type climates, terminal drought induces grain yield losses in wheat. Antitranspirants can reduce the impacts of terminal drought and improve yield, but the mechanisms involved are not fully understood. Among other impacts, drought elevates endogenous abscisic acid (ABA) concentration. Here, the effectiveness of a film antitranspirant (di-1-p-menthene) was studied in relation to plant water status and spike ABA. The objective was to determine whether drought amelioration with di-1-p-menthene was solely mediated through a reduction in ABA by comparing its effects to that of fluridone (an ABA inhibitor). The treatments were assessed in a randomized complete block design in two field experiments in spring and summer of 2020, with six and eight replicate blocks, respectively, at Harper Adams University, UK, to compare their effects on spike ABA, gas exchange and agronomic traits under progressive drought conditions. Di-1-p-menthene was applied at 1 l/ha; and fluridone at 10, 20 and 50 μM concentrations, at flag leaf emergence, growth stage 37 (GS37). Drought increased spike ABA and downregulated photosynthesis. Di-1-p-menthene and fluridone at some concentrations, reduced spike ABA and photosynthesis. Di-1-p-menthene suppressed transpiration and spike ABA, each by 21% but increased grain yield by 27%. In contrast, although fluridone (at 10 and 50 μM) also reduced spike ABA (by 16%), overall, it did not alter transpiration or grain yield. The results suggest that yield improvement with di-1-p-methene is mediated through mechanisms that involve conservation of plant water linked to reduced transpiration, with inhibition of spike ABA playing a secondary role.

Prescribed burning mitigates the severity of subsequent wildfires in Mediterranean shrublands

BackgroundPrescribed burning (PB) is becoming relevant in fuel reduction and thus fire hazard abatement in fire-prone ecosystems of southern Europe. Yet, empirical evidence on the effectiveness of this practice to mitigate wildfire severity in Mediterranean shrublands is non-existent, despite being the focus of PB efforts in this region. Here, we intended to quantify the protective effect of PB treatment units (2005–2021) to subsequent wildfire severity in shrublands across mainland Portugal, as well as the relative contribution and complex interactions between drivers of wildfire severity in PB-treated areas and untreated neighboring counterparts through Random Forest regression. We leveraged cloud-computing remote sensing data processing in Google Earth Engine to estimate fire severity (PB and wildfire) as the Relativized Burn Ratio (RBR) using Landsat data catalog.ResultsPB treatment was particularly effective at mitigating wildfire severity at the first PB-wildfire encounter in shrublands, with a mean reduction of around 24% in RBR units. Fuel age (i.e., time since prescribed burning) in PB-wildfire intersection areas overwhelmed to a large extent the effect of fire weather, burning probability, and PB severity. The mitigating effect of PB on wildfire severity persisted for a fuel age of around 5 years. However, this effect decreased with increasingly adverse fire weather conditions, such that variation in wildfire severity was somewhat insensitive to fuel age under extreme fire weather. Similarly, the lowest wildfire severity experienced in sites with high burning probability, along with the interaction effect observed between burning probability and fuel age, suggest that repeated PB treatments may be useful in controlling fuel accumulation and mitigating wildfire severity. The relative contribution of fire weather in explaining wildfire severity was exceedingly high in untreated areas, doubling that of the other variables in the model in the absence of PB treatment variables.ConclusionsOur results suggest that the implementation of PB treatments at intervals of less than 5 years is of paramount importance to control fuel build-up and fire hazard under extreme fire weather in productive Mediterranean shrublands. Further research on this topic is warranted in other shrublands worldwide, namely in Mediterranean-type climate regions.

Simulation of Long-Term Water Erosion in Rainfed Croplands of Eastern Washington

Highlights Water erosion in the inland Pacific Northwest was modeled with WEPP for the past (1940–1982) and present (1983–2020). Water erosion decreased from past to present in the study watersheds. Major factors are increased adoption of conservation practices and decrease in large precipitation events. Abstract. Water erosion is an ongoing problem in eastern Washington due to its hilly terrain, highly erodible silt loam soils, rain on thawing soil, and the prevalence of conventional tillage. The region is characterized by a Mediterranean-type climate with warm, dry summers and cool, wet winters. Three distinct precipitation zones, with annual totals low (<380 mm), intermediate (380–460 mm), and high (>460 mm), dictate the area’s crop rotations. A unique 43-year (1940–1982) dataset of winter erosion measured on multiple agricultural fields in Whitman County, eastern Washington, by Verle Kaiser, a USDA Soil Conservation Service agronomist, showed annual erosion rates averaging 53.8 Mg ha-1, far exceeding the current Natural Resources Conservation Service tolerable limit of 11 Mg ha-1 yr–1 for the soils in the area. Kaiser’s field data allowed us to compare the historical field-measured erosion rates with those simulated by the WEPP (Water Erosion Prediction Project) model. Anthropogenic factors, such as tillage and crop rotation, change with time. Conservation tillage, including reduced- and no-till, has been increasingly adopted in eastern Washington since the mid-1980s. The specific objectives of this study were to (1) apply the WEPP model to simulate soil erosion in eastern Washington and evaluate the interactive effects of climate and management, in addition to topography and soil, on water erosion in the study area, and (2) compare the simulation results with Kaiser’s historical field dataset and elucidate the long-term soil erosion trend. The WEPPcloud interface was used to delineate a watershed within each precipitation zone of the study area. Climate inputs were divided into two periods: the past (1939–1982) and the present (1983–2020). Erosion has noticeably decreased from the past to the present, with WEPP simulated annual erosion averaging 13.5, 34.5, and 52.6 Mg ha-1 for the past, and 9.5, 14.1, and 15.5 Mg ha-1 for the present, in the selected watersheds in the low-, intermediate-, and high-precipitation zones, respectively. The decreasing trend was primarily due to the increased adoption of conservation tillage and crop rotation, as well as a decrease in the number of high-intensity precipitation events in the present climate. Keywords: Inland Pacific Northwest, Soil erosion by water, Temporal trend, WEPP.

SoCal EcoServe: an online mapping tool to estimate wildfire impacts in southern California

Background Wildfires in Mediterranean-type climate regions have numerous impacts on the ecosystem services provided by native shrublands, however, quantifying these impacts is challenging. Aims We developed a reproducible method to quantify fire impacts on ecosystem services and created a tool for resource managers in southern California. Methods The SoCal EcoServe tool consists of two components: a desktop tool and an online mapping tool. We used the Alisal Fire of 2021 as a case study and quantified: aboveground live carbon storage using pre- and post-fire biomass data; water runoff, groundwater recharge and sediment erosion retention by integrating data on burn severity into hydrological and sediment erosion models; and estimated recreation services and biodiversity using pre-fire data. Key results We estimated the Alisal Fire resulted in an immediate post-fire reduction in carbon storage of 25%, of which 20% was estimated to be permanently lost. Water runoff increased by 21%, groundwater recharge 7-fold, and sediment erosion increased 24-fold. Conclusions The EcoServe tool provides an initial approximation of wildfire impacts that can support damage assessments post-fire, track carbon storage and help identify priorities for post-fire restoration. Implications We intend the tool to be used by USDA Forest Service resource managers of shurblands in southern California. However, it can provide the framework for future work in shrublands throughout the western USA.

The influence of the weather conditions on the flowering time of crocuses from the collection of the Subtropical Scientific Center of the Russian Academy of Sciences

Iridaceae is a large family of herbaceous plants with numerous species and cultivars, diverse in the habitus and structure of aboveground and underground organs, colour and shape of the flower, as well as in terms and duration of phenological phases. The earliest flowering is specific for representatives of the genus Crocus. The purposeful formation and study of genetic collections of ornamental crops, including Crocus, was started by Federal Research Centre the Subtropical Scientific Centre of the Russian Academy of Sciences in the 1960s. A large number of cultivars have been introduced and studied. The aim of the work is to study the influence of the weather conditions on the flowering terms of crocuses in the humid Russian subtropics on the Black Sea coast of Krasnodar Territory. This unique region belongs to a Mediterranean-type climate with relatively warm winters. The work was carried out in 2021-2023 according to the methods generally accepted in the introduction, as well as those being finalized by the Centre. Mathematical processing was performed in the Microsoft Office Excel 2007 program. The objects of research are 19 crocus cultivars from the bioresource collection (FRC SSC of RAS), including Crocus vernus - 7; C. chrysanthus - 4; C. tommasinianus - 4, 1 each C. flavus, C. biflorus, C. sublimis, C. olivieri. In the course of the work carried out, it has been found that climatic conditions of the humid Russian subtropics make it possible to successfully implement introduction studies on Crocus cultivars.

Development and validation of phenological models for eight varieties of sweet cherry (Prunus avium L.) growing under Mediterranean climate condition

The projected increase in temperatures caused by climate change will modify the phenological stages of sweet cherry in Mediterranean-type climate regions. This study aimed to develop and validate phenology models for eight sweet cherry varieties (Sam, Lapins, Rainier, Royal D, Santina, Regina, Kordia, Sweet Heart) in the Maule Region, Chile. The models were based on growing degree days (GDD), and the stochastic monomolecular model was employed to account for the randomness caused by measurement errors affecting the prediction of phenological states. A dataset of phenological stages was compiled over four growing seasons: 2017-2018, 2018-2019, 2019-2020, and 2020-2021. The results revealed a significant correlation (with R2 values between 0.96 and 0.98) the modified phenological (PS) scale of Biologische Bundesanstalt, Bundessortenamt, and Chemical Industry (BBCH) and GDD for all eight varieties. The validation of the model demonstrated root mean square error (RMSE), mean absolute error (MAE), and model efficiency (FE) values ranging from 1 to 1.3, 0.79 to 1.1, and 0.82 to 0.92, respectively. Finally, monomolecular model estimated the modified scale of BBCH with errors less than 2 %.

The admixture of Quercus sp. in Pinus sylvestris stands influences wood anatomical trait responses to climatic variability and drought events.

Forests are threatened by increasingly severe and more frequent drought events worldwide. Mono-specific forests, developed as a consequence of widespread management practices established early last century, seem particularly susceptible to global warming and drought compared with mixed-species forests. Although, in several contexts, mixed-species forests display higher species diversity, higher productivity, and higher resilience, previous studies highlighted contrasting findings, with not only many positive but also neutral or negative effects on tree performance that could be related to tree species diversity. Processes underlying this relationship need to be investigated. Wood anatomical traits are informative proxies of tree functioning, and they can potentially provide novel long-term insights in this regard. However, wood anatomical traits are critically understudied in such a context. Here, we assess the role of tree admixture on Pinus sylvestris L. xylem traits such as mean hydraulic diameter, cell wall thickness, and anatomical wood density, and we test the variability of these traits in response to climatic parameters such as temperature, precipitation, and drought event frequency and intensity. Three monocultural plots of P. sylvestris and three mixed-stand plots of P. sylvestris and Quercus sp. were identified in Poland and Spain, representing Continental and Mediterranean climate types, respectively. In each plot, we analyzed xylem traits from three P. sylvestris trees, for a total of nine trees in monocultures and nine in mixed stands per study location. The results highlighted that anatomical wood density was one of the most sensitive traits to detect tree responses to climatic conditions and drought under different climate and forest types. Inter-specific facilitation mechanisms were detected in the admixture between P. sylvestris and Quercus sp., especially during the early growing season and during stressful events such as spring droughts, although they had negligible effects in the late growing season. Our findings suggest that the admixture between P. sylvestris and Quercus sp. increases the resilience of P. sylvestris to extreme droughts. In a global warming scenario, this admixture could represent a useful adaptive management option.