Mediterranean Climate Regions Research Articles

Fire impacts on soil and post fire emergency stabilization treatments in Mediterranean-climate regions

Wildfires are non-controlled large-scale fires of various vegetation types that have long affected the Mediterranean- climate regions, but their increased frequency and severity has led to the degradation of the ecosystems. Particularly in Chile, 147 major wildfires in 2017, were responsible of burning 546 678 ha, which included 28 729 ha of traditional small-scale non irrigated agricultural systems, highlighting the vulnerability of these agricultural soils to wildfires. Soil biological properties are more sensitive to heating than physicochemical properties. Thus, a reduction of microbial communities and associated enzyme activities generally occur in low-intensity fires (< 200 °C). Most significant changes in physicochemical properties of soil occurring in moderately intense fires (250 to 450 °C) are increases of soil pH, nutrient availability, bulk density and soil water repellency, whereas soil aggregate stability and water holding capacity generally decrease. When vegetation cover is completely destroyed by fire, emergency stabilization treatments such as mulching and seeding provide an immediate ground cover to reduce soil erosion and preserve nutrients. Therefore, it is important to define the impacts of wildfire on soil properties of agricultural lands to establish a roadmap to implement an adequate and viable restoration.

RELATIONSHIPS BETWEEN VEGETATION INDICES AND RAINFALL AND PET AT DIFFERENT TIME-LAGS: A STUDY AT A MEDITERRANEAN TO ARID GRADIENT

Abstract. The climatic gradient between the Judean Lowland and the Negev Desert in Central Israel represents a transition zone between dense shrublands in the North, and desert fringe Batha and Irano-Turanian vegetation in the South, characterizing wide Mediterranean Type Climate regions around the world. Understanding the expected response of these water-limited ecosystems to climate change presents a significant challenge due to the high geodiversity of Mediterranean environments. Studying relationships between vegetation patterns and climatic parameters is fundamental for this purpose, and remote sensing provides a valuable tool for investigating these relationships over large regions. This study aims at examining the relationships between NDVI extracted from Sentinel2 and rainfall and PET accumulated over 1 to 6 months. The analysis was first conducted for 38 sites (100×100 meters) across the climatic gradient for three years representing high (2016), low (2017), and average (2018) rainfall. Results indicate that the highest correlation between NDVI and climatic parameters is achieved for accumulation interval of two months. Least-squares analysis was then utilized for calculating the per-pixel regression coefficients between NDVI and corresponding rainfall and PET. Classification of the multi-temporal NDVI (2016–2018) and of the linear regressions’ coefficients between NDVI and rainfall and PET at accumulation interval of 2 months yielded both high accuracies. Since these slope and intercept coefficients can be perceived as representing the water-use regime at each pixel, the similarity between the classification results suggests that multi-temporal NDVI typologies correspond water-use regime typologies across desert fringe ecosystems at the margins of Mediterranean regions.

Response of two riparian woody plants to Phytophthora species and drought

Disease combined with drought poses an important threat to plant survival, often compromising success in the restoration of riparian forests. Thus, understanding how biotic and abiotic stressors may affect plant survival and growth performance can greatly increase the success of ecosystem management strategies. The purpose of this study was to understand how two plant species, often used together in restoration of riparian ecosystems but with different ecological preferences, would respond to infection by each of two Phytophthora species in Mediterranean-climate regions, in the absence or presence of a simulated drought. Saplings of the drought resistant species Frangula californica, and of the riparian species Alnus rhombifolia were each inoculated in a greenhouse experiment with one of two Phytophthora species and exposed to two watering regimes. Saplings were allocated to six treatments, combining three levels of pathogen inoculation (no inoculation, inoculation with Phytophthora cactorum and inoculation with Phytophthora crassamura), and two watering regimes (well-watered and drought). The response of A. rhombifolia and F. californica saplings was assessed through the observation of health metrics and morphological parameters. Results showed that both P. cactorum and P. crassamura are important pathogens of A. rhombifolia and F. californica. As expected, drought conditions were the main cause of decline and mortality in A. rhombifolia saplings, while water availability was a facilitator of P. cactorum infection in F. californica saplings. We observed two seemingly contrasting results in A. rhombifolia saplings: infection by Phytophthora spp. decreased survival in well-watered plants, while the opposite was recorded for saplings under drought conditions whose survival increased in Phytophthora-inoculated treatments. Saplings of F. californica were able to cope with drought conditions, even when infected by Phytophthora species and water availability increased root infection and decreased sapling survival. We conclude that the continued use of F. californica and A. rhombifolia in sites infested by Phytophthora species can be beneficial in restoration, if appropriate management actions are adopted. Such actions include avoiding the planting of F. californica saplings in areas subjected to water accumulation, and ensuring that A. rhombifolia is planted in areas where drought stress is minimal and where Phytophthora species are possibly absent. We also emphasize the importance of ensuring that plant stock used in revegetation projects is not infected by Phytophthora species, and that biotic and abiotic risks are assessed prior to restoration actions.

Installation Season May Significantly Impact Time Required for Subterranean Termites to Find and Feed on In-Ground Baits.

Simple SummaryInsecticide baits for use against subterranean termites have been shown to be highly effective, but the time required for termites to find and feed on baits may be a barrier to adoption in some areas. One explanation for this “time-to-attack” problem is that termite foraging near the soil surface may be limited during inhospitable periods. In California, characterized by a hot-summer Mediterranean climate, western subterranean termites have mostly been observed near the surface during the wet season, suggesting that baits installed in summer may sit uninvestigated for many months. To test this hypothesis, we established research plots in areas of known termite incidence, installing baits on four different dates over a one-year period and then recording termite activity every 60 days for two years. As expected, most foraging in these stations was observed in winter and spring. Time-to-attack for stations installed at the beginning of winter was significantly less than for stations installed at the beginning of summer (194 d vs. 296 d). These findings may help pest control operators in regions with pronounced dry periods to optimize their use of bait station systems by targeting specific installation seasons.Rhinotermitid termites, serious pests of wooden structures throughout the world, are commonly controlled with chitin synthesis inhibitor bait systems. Seasonal termite foraging patterns in some regions may prolong bait interception time, however, significantly decreasing colony elimination speed. We hypothesized that installing baits immediately prior to the season of highest foraging activity will minimize interception time when baiting for Reticulitermes spp. in California, a region characterized by a hot-summer Mediterranean climate. To test this theory, we installed three different bait systems on four dates corresponding to the major seasons (spring, summer, autumn, winter) at five field locations known to harbor the target species. We then recorded initial termite discovery events every 60 days for two years, considering effects of installation season, bait system, site, and distance from previously observed termite incidence on bait interception time. Observed foraging activity in bait stations was highest during late winter and spring. Baits installed during winter exhibited interception times more than 100 days shorter than those of baits installed during summer. From these findings, we conclude that colony elimination speed and perceived CSI bait utility may be increased in Mediterranean climate regions when baits are installed immediately prior to the wet season.

Hardening Blueberry Plants to Face Drought and Cold Events by the Application of Fungal Endophytes

Harsh environmental conditions derived from current climate change trends are among the main challenges for agricultural production worldwide. In the Mediterranean climatic region of central Chile, sudden occurrence of spring cold temperatures in combination with water shortage for irrigation (drought) constitutes a major limitation to highbush blueberry (Vaccinium corymbosum) plantations, as flowering and fruiting stages are highly sensitive. Hardening crops may be achievable by boosting beneficial interactions of plants with microorganisms. Inoculation with symbiotic fungi isolated from plants adapted to extreme environments could be a good strategy, if they are able to maintain functional roles with non-original hosts. Here, we evaluated the effect of two Antarctic fungal endophytes (AFE), Penicillium rubens and P. bialowienzense, on the tolerance of V. corymbosum plants to cold events in combination with drought under controlled conditions. Inoculated and uninoculated plants were exposed for a month to one event of a cold temperature (2 °C/8 h) per week with or without drought and were evaluated in physiological, biochemical, and molecular variables. A complementary set of plants was kept under the same environmental conditions for two additional months to evaluate survival as well as fruit weight and size. There was an overall positive effect of AFE on plant performance in both environmental conditions. Endophyte-inoculated plants exhibited higher gene expression of the Late Embryogenesis Abundant protein (LEA1), higher photochemical efficiency (Fv/Fm), and low oxidative stress (TBARS) than uninoculated counterparts. On the other hand, plant survival was positively affected by the presence of fungal endophytes. Similarly, fruit diameter and fruit fresh weight were improved by fungal inoculation, being this difference higher under well-watered condition. Inoculating plants with fungal endophytes isolated from extreme environments represents a promising alternative for hardening crops. This is especially relevant nowadays since agriculture is confronting great environmental uncertainties and difficulties which could became worse in the near future due to climate change.

Spatial and temporal patterns of Holocene precipitation change in the Iberian Peninsula

Precipitation is a key climate parameter of vegetation and ecosystems in the Iberian Peninsula. Here, we use a regional pollen–climate calibration model and fossil pollen data from eight sites from the Atlantic coast to southern Spain to provide quantitative reconstructions of annual precipitation trends and excursions and their regional patterns for the last 11 700 years. The Early Holocene (11 700 to 11 000 cal. a BP) was characterized by high precipitation values followed by a slowly declining trend until about 9000 cal. a BP in the south and about 8000 cal. a BP in the north. From 8000 to 6000 cal. a BP the reconstructed precipitation values are the highest in most records, especially in those located in the Mediterranean climatic region in the southern part of the peninsula, with maximum values nearly 100% higher than the modern reconstructed values. The results suggest a declining precipitation during the Late Holocene in the south, with a positive excursion at around 2500 cal. a BP, while in the north precipitation remained high until 500 cal. a BP. However, the Late Holocene climate reconstructions in the Iberian Peninsula are biased by intensifying human impact on vegetation. The statistical time series analyses using SiZer technique do not indicate any statistically significant high‐frequency drought events in the region. In general, our results suggest regional differences in the precipitation patterns between the northern and southern parts of the peninsula, with a more distinct Middle Holocene period of high humidity in the south.

Ovine footrot in Southern Portugal: Detection of Dichelobacter nodosus and Fusobacterium necrophorum in sheep with different lesion scores

The Mediterranean climate region of Alentejo in the Southern of Portugal is an important sheep production centre but little is known about the presence and characteristics of Dichelobacter nodosus in association with Fusobacterium necrophorum in the different footrot lesion scores. DNA from 261 interdigital biopsy samples, taken from 14 footrot affected flocks and from three non-affected flocks, were analysed for the presence of D. nodosus and F. necrophorum by real-time PCR. Both virulence and serogroup were determined for 132 and 53 D. nodosus positive biopsy samples, respectively. The co-infection with both bacteria was the commonest epidemiological finding associated with a greater disease severity. There was a statistically significant association (p = 0.002) between footrot-affected flocks and the presence of D. nodosus. Most D. nodosus positive samples were virulent (96.2 %) and belonged to serogroup B (90 %).

Genetic Yield Gains and Changes in Morphophysiological-Related Traits of Winter Wheat in Southern Chilean High-Yielding Environments.

Both the temperate-humid zone and the southern part of the Mediterranean climate region of Chile are characterized by high wheat productivity. Study objectives were to analyze the yield potential, yield progress, and genetic progress of the winter bread wheat (Triticum aestivum L.) cultivars and changes in agronomic and morphophysiological traits during the past 60 years. Thus, two field experiments: (a) yield potential and (b) yield genetic progress trials were conducted in high-yielding environments of central-southern Chile during the 2018/2019 and 2019/2020 seasons. In addition, yield progress was analyzed using yield historical data of a high-yielding environment from 1957 to 2017. Potential yield trials showed that, at the most favorable sites, grain yield reached ∼20.46 Mg ha–1. The prolonged growing and grain filling period, mild temperatures in December-January, ample water availability, and favorable soil conditions explain this high-potential yield. Yield progress analysis indicated that average grain yield increased from 2.70 Mg ha–1 in 1959 to 12.90 Mg ha–1 in 2017, with a 128.8 kg ha–1 per-year increase due to favorable soil and climatic conditions. For genetic progress trials, genetic gain in grain yield from 1965 to 2019 was 70.20 kg ha–1 (0.49%) per year, representing around 55% of the yield progress. Results revealed that the genetic gains in grain yield were related to increases in biomass partitioning toward reproductive organs, without significant increases in Shoot DW production. In addition, reducing trends in the NDVI, the fraction of intercepted PAR, the intercepted PAR (form emergence to heading), and the RGB-derived vegetation indices with the year of cultivar release were detected. These decreases could be due to the erectophile leaf habit, which enhanced photosynthetic activity, and thus grain yield increased. Also, senescence of bottom canopy leaves (starting from booting) could be involved by decreasing the ability of spectral and RGB-derived vegetation indices to capture the characteristics of green biomass after the booting stage. Contrary, a positive correlation was detected for intercepted PAR from heading to maturity, which could be due to a stay-green mechanism, supported by the trend of positive correlations of Chlorophyll content with the year of cultivar release.

Enhancing agriculture recovery of

Context The rhizosphere is an environment created by interactions between root exudates and microorganisms. Interactions are beneficial due to certain components having a plant growth promoting rhizobacteria (PGPR) effect. Aims This study consists of the isolation, screening of PGPR from the rhizosphere of Olea europaea L. of a Mediterranean climatic region in Algeria and the study of their effects on growth of two agronomic vegetables Phaseolus vulgaris L. and Cucurbita pepo L. Methods Based on their ability to produce the PGPR molecules indole-3-acetic acid (IAA), phosphatase and siderophores, three rhizobacteria (S25, S75, and S79) were chosen for in vivo tests and capacity to produce the cell wall degrading enzymes chitinase, lipase, protease, glucanase, cellulase, and and phospholipase. They were also examined using scanning electron microscopy (SEM) and analysed using matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF MS) for identification. Key results Bacterial strains identified as Bacillus cereus and Bacillus thuringiensis were able to enhance significantly germination of the two vegetables at P &lt; 0.001. Vegetative parameters of C. pepo were significantly affected by the bacterial inoculation. We noted increases in stem length (P &lt; 0.05), number of flowers (P &lt; 0.01), and root length (P &lt; 0.001). Conclusion The bacterial isolates of this study provide biological options in treatments originating from alternate hosts. Implications They provide hope for companion/intercrop planting schemes, leading to optimisation of agricultural yields in agroecological blends.

Techno-economic assessment of hybrid energy flexibility systems for islands’ decarbonization: A case study in Italy

Geographical Islands have been considered a challenging environment to test renewable energy integration strategies as well as cutting-edge technologies due to the alternation between actual grid-connected and island mode. Energy system flexibility is foreseen as a strategy to integrate higher renewable share and reduce adverse events to the Power Grid. At the same time, the storage options for supporting high Renewable Energy Systems (RES) share remain still just an option in many countries, especially for Europe. In this research, the Catania city is considered for the case study in the Mediterranean climate region from Sicily Island in Italy. HOMER software is used to simulate the economic and technical use of photovoltaic panels/wind turbines/fuel cell/electrolyzer and hydrogen tank to meet the demand for 2 MW energy. It is pointed that photovoltaic panels and wind turbines can complement each other in some months of the year for production power. Photovoltaic panels provided 72% of the total energy and have higher efficiency than wind turbines and fuel cells. The results show that to meet the needs of 2 MW of the region, a capital cost of 4.85 million euros should be spent, which return of investment (ROI) is 2.59 million euros in the estimated 25-year life of the project.

Biomimetic Architecture Towards Bio Inspired Adaptive Envelopes: In Case of Plant Inspired Concept Generation

In recent decades, the value of architecture become more due to its importance for reducing detrimental effects on the environment and natural capital. To minimize the building's impact on the environment, architectural designs should be highly incorporated into the environment rather than behaving as a separate element focused on a single issue. To address this problem, different methods and design approaches have been introduced. However, exploring the natural solutions for survival can provide invaluable data which can address the human-caused problems. Throughout decades, nature has been survived and evolved. Biological solutions due to their adaptability and multi-functionality are great source of inspiration. This article with help of content analysis method aims to review the concept of biomimetic design in architecture. And proposes plant-inspired solutions for envelope design which can play significant role on buildings’ energy efficiency. Thus, the plant-inspired concepts to be integrated on adaptive envelopes were studied. And a framework for concept generation introduced. Furthermore, a case study on an existing building envelope in the Mediterranean climate region presented and two plant-inspired techniques proposed and conceptually applied.

The environmental framework of temporary ponds: A tropical-mediterranean comparison

Temporary ponds are distributed worldwide, providing significant ecological services. Their limnological features are influenced by a set of regional (mainly climate) and local (natural or anthropogenic) factors. To evaluate the differences in their ecological functioning in distant geographic regions, we analysed the main features of 90 temporary ponds located in three distinct areas: two mediterranean-climate regions (Eastern Iberian Peninsula and Central Chile) and a tropical setting in Costa Rica. Each pond was surveyed thrice during the hydrological cycle of 2017–2018, and five sets of parameters were obtained: limnological, hydrogeomorphological, biotic, landscape and climatic variables. Through multivariate analyses, we determined the environmental heterogeneity of each region and the main environmental differences among them. As expected, hydrogeomorphological factors did not differ between regions, but climate variables showed marked differences between the tropical and the two mediterranean regions. We also detected clear differences between mediterranean and tropical ponds in terms of their mineralization patterns (mainly conductivity and alkalinity), natural vegetation cover and land use. Despite the regional similarities between mediterranean regions, some strong differences were found concerning vegetation cover, nutrient concentration and trophic state, probably associated to human activities (agriculture and extensive stockbreeding).

Evapotranspiration Trends and Interactions in Light of the Anthropogenic Footprint and the Climate Crisis: A Review

Evapotranspiration (ET) is a parameter of major importance participating in both hydrological cycle and surface energy balance. Trends of ET are discussed along with the dependence of evaporation to key environmental variables. The evaporation paradox can be approached via natural phenomena aggravated by anthropogenic impact. ET appears as one of the most affected parameters by human activities. Complex hydrological processes are governed by local environmental conditions thus generalizations are difficult. However, in some settings, common hydrological interactions could be detected. Mediterranean climate regions (MCRs) appear vulnerability to the foreseen increase in ET, aggravated by precipitation shifting and air temperature warming, whereas in tropical forests its role is rather beneficial. ET determines groundwater level and quality. Groundwater level appeared to be a robust predictor of annual ET for peatlands in Southeast Asia. In semi-arid to arid areas, increases in ET have implications on water availability and soil salinization. ET-changes after a wildfire can be substantial for groundwater recharge if a canopy-loss threshold is surpassed. Those consequences are site-specific. Post-fire ET rebound seems climate and fire-severity-dependent. Overall, this qualitative structured review sets the foundations for interdisciplinary researchers and water managers to deploy ET as a means to address challenging environmental issues such as water availability.

Alternaria as an Inducer of Allergic Sensitization.

Alternaria alternata is a saprophytic mold whose spores are disseminated in warm dry air, the typical weather of the Mediterranean climate region (from 30° to 45°), with a peak during the late summer and early autumn. Alternaria spores are known to be biological contaminants and a potent source of aeroallergens. One consequence of human exposure to Alternaria is an increased risk of developing asthma, with Alt a 1 as its main elicitor and a marker of primary sensitization. Although the action mechanism needs further investigation, a key role of the epithelium in cytokine production, TLR-activated alveolar macrophages and innate lymphoid cells in the adaptive response was demonstrated. Furthermore, sensitization to A. alternata seems to be a trigger for the development of co-sensitization to other allergen sources and may act as an exacerbator of symptoms and an elicitor of food allergies. The prevalence of A. alternata allergy is increasing and has led to expanding research on the role of this fungal species in the induction of IgE-mediated respiratory diseases. Indeed, recent research has allowed new perspectives to be considered in the assessment of exposure and diagnosis of fungi-induced allergies, although more studies are needed for the standardization of immunotherapy formulations.

The composition, geography, biology and assembly of the coastal flora of the Cape Floristic Region.

The Cape Floristic Region (CFR) is globally recognized as a hotspot of plant diversity and endemism. Much of this diversity stems from radiations associated with infertile acid sands derived from sandstones of the geologically ancient Cape Fold Belt. These ancient montane floras acted as the source for most subsequent radiations on the Cape lowlands during the Oligocene (on silcretes) and Mio–Pliocene (on shales). The geomorphic evolution of the CFR during the Plio–Pleistocene led to the first large-scale occurrence of calcareous substrata (coastal dunes and calcarenites) along the Cape coast, providing novel habitats for plant colonization and ensuing evolution of the Cape coastal flora—the most recent diversification event in the Cape. Few studies have investigated the CFR’s dune and calcarenite floras, and fewer still have done so in an evolutionary context. Here, we present a unified flora of these coastal calcareous habitats of the CFR and analyze the taxonomic, biological and geographical traits of its component species to gain insights into its assembly. The Cape coastal flora, comprising 1,365 species, is taxonomically dominated by the Asteraceae, Fabaceae and Iridaceae, with Erica, Aspalathus and Agathosma being the most speciose genera. In terms of growth-form mix, there is a roughly equal split between herbaceous and woody species, the former dominated by geophytes and forbs, the latter by dwarf and low shrubs. Species associated with the Fynbos biome constitute the bulk of the flora, while the Subtropical Thicket and Wetland biomes also house a substantial number of species. The Cape coastal flora is a distinctly southern African assemblage, with 61% of species belonging to southern African lineages (including 35% of species with Cape affinity) and 59% being endemic to the CFR. Unique among floras from the Cape and coastal Mediterranean-climate regions is the relatively high proportion of species associated with tropical lineages, several of which are restricted to calcareous substrata of the CFR. The endemic, calcicolous component of the flora, constituting 40% of species, represents 6% of the Cape’s regional plant diversity—high tallies compared to other biodiversity hotspots. Most coastal-flora endemics emerged during the Plio–Pleistocene as a product of ecological speciation upon the colonization of calcareous substrata, with the calcifugous fynbos floras of montane acid substrata being the most significant source of this diversification, especially on the typically shallow soils of calcarenite landscapes. On the other hand, renosterveld floras, associated with edaphically benign soils that are widespread on the CFR lowlands, have not been a major source of lineages to the coastal flora. Our findings suggest that, over and above the strong pH gradient that exists on calcareous substrata, soil depth and texture may act as important edaphic filters to incorporating lineages from floras on juxtaposed substrata in the CFR.

Dragonfly Conservation in the Increasingly Stressed African Mediterranean-Type Ecosystems

Freshwater habitats worldwide are experiencing many threats from environmental and anthropogenic sources, affecting biodiversity and ecosystem functioning. In Africa, particularly in Mediterranean climate zones, rapid human population growth is predicted to have great impact on natural habitats besides naturally occurring events such as unpredictable drought frequency and severity. Here, we analyze the potential correlation between odonate assemblage conservation priority (measured with the Dragonfly Biotic Index: DBI) and the magnitude of climate change and human perturbation in African regions with a dominant Mediterranean climate, namely Northern (NAR: Morocco, Algeria and Tunisia) and Southern African region (SAR: South Africa). Using a compilation of studies assessing odonate assemblages in lotic and lentic habitats of both regions (295 sites in NAR and 151 sites in SAR), we estimated DBI, temporal change in average annual temperature (T), annual precipitation (P), and human footprint index (HFI) in each site, then we tested whether sites with different levels of DBI were associated with different magnitudes of climatic and anthropogenic change. We estimated past (between 1980–1999 and 2000–2018) and future changes (between 1980–1999 and 2081–2100) in T and P based on three CMIP6 scenarios representing low (SSP126), moderate (SSP245), and high emission (SSP585), as well as the change in HFI from 1993 to 2009. We found that assemblages with higher DBI (i.e. higher conservation priority) encountered lower increase in T and slightly greater decrease in P than assemblages with lower DBI (i.e. lower conservation priority) in NAR during 1980–2018, but are projected to experience higher increase in T and lower decrease in P in future projections for 2081–2100. In SAR, the increase in T was mostly similar across assemblages but the decline in P was higher for assemblages with higher DBI during 1980–2018 and 2081–2100, suggesting that assemblages of higher conservation priority in SAR are threatened by drought. While HFI showed an overall increase in NAR but not in SAR, its temporal change showed only minor differences across assemblages with different DBI levels. We discuss the importance of management plans to mitigate the effects of climatic and anthropogenic threats, so improving conservation of odonate assemblages in these regions.

Edge effects on the realised soil seed bank along microclimatic gradients in temperate European forests

Despite the crucial role of the seed bank in forest conservation and dynamics, the effects of forest edge microclimate and climate warming on germination responses from the forest seed bank are still almost unknown. Here, we investigated edge effects on the realised seed bank and seedling community in two types of European temperate deciduous forest, one in the Oceanic and one in the Mediterranean climatic region. Responses in terms of seedling density, diversity, species composition and functional type of the seed bank at the forest edge and interior were examined along latitudinal, elevational and stand structural gradients by means of soil translocation experiments. Moreover, we translocated soil samples from high to low elevation forests in the two regions, thus performing a warming simulation. Density, species diversity and mortality of the seedlings varied with region and elevation. Seedling density also differed between forest edge and interior position, while seedling cover mainly depended on forest structure. Both the edge and interior forest seed bank contained a high proportion of generalist species. In Belgium, a more homogeneous seed bank was found at the forest edge and interior, while in Italy compositional and ecological differences were larger: at the forest edge, more light and less moisture demanding seedling communities developed, with a higher proportion of generalists compared to the interior. In both regions, the upland-to-lowland translocation experiment revealed effects of warming on forest seed banks with thermophilization of the realised communities. Moreover, edge conditions shifted the seedling composition towards more light-demanding communities. The establishment of more light and warm-adapted species from the seed bank could in the long term alter the aboveground vegetation composition, with communities becoming progressively richer in light-demanding generalists and poorer in forest specialists.

Flow regime change alters shredder identity but not leaf litter decomposition in headwater streams affected by severe, permanent drying

Abstract Climate change is altering hydrologic regimes globally. In the Mediterranean climate region of south‐western Australia (SWA), climate drying has caused many perennial streams to switch to intermittent flow regimes. Shifts in flow regime are expected to alter physical and biological processes in streams, including litter decomposition, which is the basis of detrital food webs. Decomposition of jarrah (Eucalyptus marginata) leaves and associated macroinvertebrates, were measured over 320 days in 2018–19 using leaf bags in four headwater streams in SWA. Two streams retained perennial reaches and two were formerly perennial streams that are now intermittent. Pre‐planned comparisons that formed a partial multiple before–after, control–impact design were used to compare the results to an experiment conducted in 1982–83 in some of the same streams when all were perennially flowing. Both experiments used coarse and fine‐mesh bags containing 10 g of dry leaves. In one perennial stream, coarse bags lost more weight than fine bags at the last sampling time only, when shredding caddisflies arrived on the leaf bags. In the other perennial stream, leaf‐mining chironomids entered fine‐mesh bags and accelerated decomposition so that they lost more weight than the coarse‐mesh bags. There was no difference in weight loss between fine and coarse‐mesh leaf bags in the two intermittent streams. In 2018–19, decomposition was slower in dry reaches of intermittent streams than in perennial reaches. Leaf weight loss increased with the resumption of flow in intermittent streams, so that by the end of the experiment, similar amounts of leaf weight had been lost in intermittent and perennial reaches. Thus, although the temporal pattern of decomposition differed between intermittent and perennial reaches, after 320 days, they had reached a similar endpoint. Over similar experimental duration, mean leaf weight remaining in perennial reaches at the end of the experiment did not differ between the 1982–83 study and 2018–19, showing that leaf decomposition had not changed in reaches that retained perennial flow. As mean leaf weight remaining also did not differ between intermittent and perennial streams in 2018–19, leaf decomposition was robust to flow regime change. However, since 1982–83, these streams have lost populations of shredding caddisflies and stoneflies, which were replaced by other shredders (e.g. leaf mining chironomids Stenochironomus sp.), showing that there was some redundancy amongst shredder species. As climate change progresses, drying flow regimes will become commonplace in Mediterranean (and other) climate regions globally. This study indicates that litter decomposition may be maintained as streams transition to intermittency although shredder species may change. However, the impact of shredding species on leaf decomposition varies amongst studies, so effects of the loss of shredder species sensitive to drying may also vary, and in some cases their loss may substantially alter ecosystem processes.

Leaf Thermal and Chemical Properties as Natural Drivers of Plant Flammability of Native and Exotic Tree Species of the Valparaíso Region, Chile.

Forest fires are one of the main environmental threats in Chile. Fires in this Mediterranean climate region frequently affect native forests and exotic plantations, including in several cases urban and rural settlements. Considering the scarcity of information regarding the fire response dynamics of tree species that are frequently affected by fires, this study aims to establish a flammability classification according to the evolution of the fire initiation risk presented by the most affected forest species in the Valparaíso region. Three exotic species, Eucalyptus globulus, Pinus radiata, and Acacia dealbata, and two native species, Cryptocarya alba and Quillaja saponaria, were studied. Flammability assays indicate that E. globulus, A. dealbata, and C. alba are extremely flammable, whereas P. radiata and Q. saponaria are flammable. Furthermore, E. globulus and A. dealbata have the highest heating values while Q. saponaria has the lowest values. The extreme flammability of E. globulus, A. dealbata, and C. alba indicates a high susceptibility to ignite. Furthermore, the high heat of combustion of E. globulus and A. dealbata can be associated with a high energy release, increasing the risk of fires spreading. In contrast, Q. saponaria has the lowest predisposition to ignite and capacity to release heat. Accordingly, this work shows that all studied tree species contain organic metabolites that are potentially flammable (sesquiterpenes, aliphatic hydrocarbons, alcohol esters, ketones, diterpenes, and triterpenes) and can be considered as drivers of flammability in vegetation. Finally, these preliminary results will aid in the construction of more resilient landscapes in the near future.

Recent changes in the rain regime over the Mediterranean climate region of Israel

Recent changes in the rain regime over the Mediterranean climate region of Israel