Mediterranean Woodlands Research Articles

Fire enhances changes in phosphorus (P) dynamics determining potential post-fire soil recovery in Mediterranean woodlands

Soil phosphorus (P), which is essential for ecosystem functioning, undergoes notable changes after fire. However, the extent to which fire characteristics affect P dynamics remains largely unknown. This study investigated the impact of type of fire (prescribed burning and natural wildfires) of different levels of severity on P dynamics in Mediterranean soils. Soil P concentrations in the organic layers were strongly affected by fire severity but not fire type. Low severity fire did not have any observable effect, while moderate fire increased soil P levels by 62% and high severity decreased soil P concentration by 19%. After one year, the soil P concentration remained unchanged in the low severity fires, while rather complex recovery was observed after moderate and high severity fires. In the mineral layers, P concentration was reduced (by 25%) immediately after the fires and maintained for one year (at 42%). 31P-NMR spectroscopy revealed almost complete post-fire mineralization of organic P forms (mono- and diesters), large increases in inorganic orthophosphate and a decrease in the organic:inorganic P ratio (Po:Pi). After one year, di-esters and orthophosphate recovered to pre-fire levels at all sites, except those where parent material composition (high pH and Fe concentration) had an enduring effect on orthophosphate retention, and thus, on the total soil P. We showed that fire severity and soil pH (and hence, soil mineralogy) played an essential role in soil P dynamics. These findings are important for reliable assessment of the effects of fire on soil P conservation and for improving the understanding the impact of prescribed burning.

Sensitivity of sub-annual grey pine (Pinus sabiniana) stem growth to water supply and demand in central California

Pinus sabiniana (grey pine) is a common associate of Quercus douglasii (blue oak) in the iconic, ecologically-rich, and economically-relevant Mediterranean woodland savannah of California, USA. While there are dozens of Q. douglasii sites in the International Tree-Ring Data Bank, P. sabiniana was conspicuously absent, and little is known about its growth patterns or water relations. Here, we introduce a new tree-ring chronology of P. sabiniana collected in central California and assess climatic drivers of annual and sub-annual growth. Specifically, we examine earlywood, latewood, and total annual ring widths and analyse their relationships with variables related to water supply (precipitation, soil moisture) and water demand (air temperature, potential evaporation rate). Annual and earlywood widths had nearly identical responses to climate, likely because annual widths mostly consisted of earlywood (mean: 88 %). In both cases, growth was strongly and positively associated with water supply and negatively associated with water demand. Soil moisture was, by far, the strongest and most temporally-consistent correlate of P. sabiniana growth: correlations between soil moisture and annual growth were >0.8 for five contiguous 3-month seasons. Other variables were significant, in part, because of their influence on soil moisture. The association between latewood growth and climate was qualitatively similar but weaker and, with the exception of soil moisture, more seasonally localised (precipitation was relevant in winter and early spring and water demand variables were relevant in summer, somewhat later in the season than for total ring width and earlywood). Further, P. sabiniana growth was nearly always more sensitive to soil moisture than growth of either co-located Q. douglasii or P. ponderosa (ponderosa pine) at a neighbouring site, suggesting that it may act as a particularly sensitive harbinger of drought stress in this ecosystem.

Fine-scale genetic structure and phenotypic divergence of a passerine bird population inhabiting a continuous Mediterranean woodland.

Genetic differentiation between populations inhabiting ecologically different habitats might appear because of limited dispersal and gene flow, which may lead to patterns of phenotypic divergence and local adaptation. In this study, we use dispersal, genotypic (24 microsatellite loci) and phenotypic (body size and clutch size) data to analyse patterns of genetic structuring and phenotypic divergence in a blue tit (Cyanistes caeruleus) population inhabiting a continuous and heterogeneous woodland along a valley. The two slopes of the valley differ in their forest formations and environmental conditions. Findings showed that most blue tits reproduced within their natal slope. Accordingly, microsatellite analyses revealed that populations of blue tits established in the two slopes show subtle genetic differentiation. The two genetic populations diverged in clutch size, exceeding the level of differentiation expected based on genetic drift, hence suggesting divergent selection (or other processes promoting divergence) on this life-history trait. Our findings reveal that restricted dispersal and spatial heterogeneity may lead to genetic differentiation among bird populations at a surprisingly small scale. In this respect, it is worth highlighting that such differentiation occurs for an organism with high dispersal capacity and within a continuous woodland. Moreover, we show that small-scale ecological differences, together with limited gene flow, can result in selection favouring different phenotypes even within the same continuum population.

Prey dynamics and breeding performance in a generalist predator: The differential role of prey density, biomass, and effective consumption rates

The breeding performance of predators is influenced by the differential consequences of prey density, prey biomass and effective consumption rates. Using camera traps at nests, we investigated whether changes in prey abundances caused functional and/or numerical responses of the common buzzard (Buteo) in a Mediterranean woodland region. After determining 1150 prey delivered to the nests by adults, we found that the biomass of prey caught was not a good indicator of its influence on individual life history traits such as productivity. Indeed, the consumption of small mammal prey, despite representing only 11% of the biomass delivered, had a much greater influence on buzzards' productivity than the consumption of snakes, which made up 47% of the biomass delivered. Live trapping evidenced that small mammals were roughly preyed according to its availability in the field, and their abundance in spring was directly related to buzzards' productivity and inversely related to hatching dates. Small mammals – mostly mice – can be considered as very suitable prey, owing quick handling times, profitability, and high energy intake. Our results pointed out the relevance of mice on buzzards' breeding performance, and altogether with the outstanding role of open-land small mammals on buzzards' demography during autumn-winter, suggested a key role of small mammals on buzzards’ ecology throughout the year cycle in the Mediterranean area studied. These findings have important implications for our understanding of the foraging strategies of generalist species and the role that habitat and environmental factors play in shaping them.

Transpiration Dynamics of Esparto Grass (Macrochloa tenacissima (L.) Kunth) in a Semi-Arid Mediterranean Climate: Unraveling the Impacts of Pine Competition.

Macrochloa tenacissima (M. tenacissima), or esparto, is a perennial tussock grass that coexists with Pinus halepensis (P. halepensis) in semi-arid Mediterranean woodlands. This research was carried out to explore diurnal transpiration at leaf level in esparto grass under different levels of pine-esparto competition and in contrasting environmental soil water conditions. The measurement period spanned from the summer of 2020 to the spring of 2021. The relationship between transpiration and competition was conducted in open and closed P. halepensis stands, and the type of leaf (green, senescent) and the maturity of the esparto grass were taken into account. We observed a higher control of transpiration in green leaves, and the correlations between the transpiration and pine competition were noted exclusively in this type of leaf. Our results demonstrated a significant impact of pine competitors (closed stands) on the transpiration of esparto grass, particularly during seasons characterized by scenarios of high water demand: the summer drought period and the commencement of the growing and flowering period (spring). Furthermore, our findings revealed a greater response to transpiration in mature bushes compared to young ones under severe water stress, indicating a higher adaptation to drought by esparto as it ages. Although our results confirmed that PAR increased transpiration in all seasons and in both stands, which is attributable to the heliophilia of esparto grass, the site effects on transpiration could also be attributable to competition for water, especially during periods of drought. These results may have important implications for the dynamics and management of these semi-arid mixed woodlands, as well as the planning of reforestation programs aimed at restoring esparto grass formations.

Effects of shrub species dominance and diversity on oak seedling survival in Mediterranean woodlands: The interplay of abiotic conditions and plant traits

Understanding plant species interactions, including facilitation and competition, is fundamental to improve the success of woody seedling establishment. This is particularly important for the restoration of sclerophyllous oak forests, one of the main forest types in Mediterranean Europe currently facing a severe lack of oak natural regeneration. However, the effects of shrub communities dominated by different species and diverse shrub communities on the establishment of Mediterranean oaks remains poorly understood. We conducted a 3-year experimental study in cork oak (Quercus suber L.) woodlands in Portugal to assess the effects of species dominance and diversity of the shrub community and associated abiotic resources on cork oak seedling emergence and survival. We hypothesized that the emergence and survival vary with the identity of the dominant shrub, due to distinct shrub functional traits affecting understory abiotic conditions. Additionally, we predict that the survival of seedlings increases with shrub diversity, driven by net facilitation processes. We sowed 960 cork oak acorns across five replicated microhabitats: four with distinct shrub species dominance and diversity and one without shrub cover. We used Bayesian statistics to model cork oak seedling emergence and survival as a function of microhabitat type and abiotic variables (soil water and temperature, soil characteristics and leaf area index). Seedling emergence and survival varied with species dominance and diversity of the shrub microhabitat. The highest survival was observed in microhabitats characterized by higher shrub diversity, and the lowest survival in microhabitats dominated by Cistus ladanifer. Maximum soil temperature was associated with higher emergence but lower survival in open conditions or areas with sparser shrub cover. Water logging constrained emergence and survival, but higher soil potassium was associated with higher survival, for all microhabitats. Our study shows that interactions between cork oak seedlings and their shrub neighbors are species and community dependent, and that a more diverse shrub composition improves cork oak seedling survival, likely due to distinct shrub traits that ameliorate the physical environment and promote facilitation. Management and restoration of Mediterranean sclerophyllous oak forests need to consider the specificity and diversity of the understory plant community, as well as the different stages of oak early life-cycle, to identify the most favorable conditions for oak establishment. This becomes particularly important under more frequent climatic extremes predicted for Mediterranean Europe.

The Role of Almond-Leaved Pear Pyrus spinosa Forssk. in Mediterranean Pasturelands Carbon Storage and Woodlands Restoration

A large portion of the Mediterranean basin suffers from a lack of organic carbon in the soil and low woody cover percentages, resulting in a very high risk of desertification. In such conditions, knowing the effects on below and above ground carbon sequestration of pioneer woody species is of great importance, although barely assessed at the individual level. In this study, we first investigated whether almond-leaved pear (Pyrus spinosa) individuals influence soil organic carbon (SOC) concentration and stock in comparison with surrounding pasturelands inside a natural reserve in Sicily, Italy. Second, we evaluated inter individual variability on such storage, testing the effects of plant height, basal diameter, canopy cover and tree structure (single or multiple stems). Soils under pear presented, on average, a significantly higher SOC than pasturelands (3.86% and 3.16%, respectively) as well as a lower bulk density (1.09 and 1.28 g cm−3, respectively). Due to a lower soil compaction, SOC stocks (130.3 and 113.9 Mg ha−1, respectively) did not differ significantly. Below and aboveground biomass carbon accounted for a small fraction of carbon stock, while neither pear structure, age nor tree structure significantly influenced SOC concentration and SOC stock. Despite the need of further investigations, our results indicate that pear may represent an excellent tree species to improve carbon storage, both while triggering the restoration of Mediterranean woodlands or increasing biodiversity in pasturelands and agroforestry systems, that, indeed, can hold high SOC if well managed.

Variable influence of photosynthetic thermal acclimation on future carbon uptake in Australian wooded ecosystems under climate change.

Climate change will impact gross primary productivity (GPP), net primary productivity (NPP), and carbon storage in wooded ecosystems. The extent of change will be influenced by thermal acclimation of photosynthesis-the ability of plants to adjust net photosynthetic rates in response to growth temperatures-yet regional differences in acclimation effects among wooded ecosystems is currently unknown. We examined the effects of changing climate on 17 Australian wooded ecosystems with and without the effects of thermal acclimation of C3 photosynthesis. Ecosystems were drawn from five ecoregions (tropical savanna, tropical forest, Mediterranean woodlands, temperate woodlands, and temperate forests) that span Australia's climatic range. We used the CABLE-POP land surface model adapted with thermal acclimation functions and forced with HadGEM2-ES climate projections from RCP8.5. For each site and ecoregion we examined (a) effects of climate change on GPP, NPP, and live tree carbon storage; and (b) impacts of thermal acclimation of photosynthesis on simulated changes. Between the end of the historical (1976-2005) and projected (2070-2099) periods simulated annual carbon uptake increased in the majority of ecosystems by 26.1%-63.3% for GPP and 15%-61.5% for NPP. Thermal acclimation of photosynthesis further increased GPP and NPP in tropical savannas by 27.2% and 22.4% and by 11% and 10.1% in tropical forests with positive effects concentrated in the wet season (tropical savannas) and the warmer months (tropical forests). We predicted minimal effects of thermal acclimation of photosynthesis on GPP, NPP, and carbon storage in Mediterranean woodlands, temperate woodlands, and temperate forests. Overall, positive effects were strongly enhanced by increasing CO2 concentrations under RCP8.5. We conclude that the direct effects of climate change will enhance carbon uptake and storage in Australian wooded ecosystems (likely due to CO2 enrichment) and that benefits of thermal acclimation of photosynthesis will be restricted to tropical ecoregions.

Species-specific growth responses to local and regional climate variability indicate the presence of a diversity portfolio effect in mediterranean tree assemblages

Understanding the role of tree biodiversity in stabilizing ecosystem processes is of paramount importance in forest ecology, especially because of increasing temperatures and droughts. The portfolio effect is one of the main hypotheses explaining the biodiversity-stability relationship that has been defined as a variance reduction effect of biodiversity in an ecosystem process, so that fluctuations over time in highly diverse communities become significantly smaller in low-diversity communities. In this work, two main objectives were established: to analyze a potential portfolio effect in a tree assemblage through functional mechanisms of compensation, and to identify the local climatic factors and teleconnections responsible for the interannual variations in the growth of tree species. The study was carried out in a region of the Iberian Peninsula with transitional climatic characteristics that allow the coexistence of needleleaf and broadleaf tree species with a wide variety of strategies and functional traits allowing them to respond differentially to climatic conditions. A dendrochronological approach was followed to analyze tree growth in relation to climate factors. We found that the magnitude and sensitivity of the response to both local climatic elements and teleconnections were species-dependent and that during climatically extreme years, the species exhibited marked differences in tree growth and compensatory responses that contributed to an increase in temporal stability. These results point to the existence of a portfolio effect in Mediterranean woodlands that supports tree diversity as an effective driver of ecosystem stability. Although the combination of dry and hot years always has a negative effect on tree growth, the association of coniferous and broadleaved (evergreen and marcescent) species at our study site could have a significantly positive influence by increasing temporal stability at landscape level through complementary functional responses.

Distance from human settlements favors wild‐type appearance of feral cats (Felis catus) in Mediterranean woodland

AbstractCamouflage is a common trait enabling animals to avoid detection by predators and prey. Patterns such as spots and stripes are convergent across carnivore families, including felids, and are hypothesized to have adaptive value through camouflage. House cats (Felis catus) were domesticated thousands of years ago, but despite artificial selection for a wide variety of coat colors, the wild‐type pattern of tabby cats is very common. We aimed to determine whether this pattern grants an advantage over other morphs in natural environments. We collected cat images taken with camera traps in natural areas near and far from 38 rural settlements in Israel, to compare the habitat use by feral cats of different colors. We tested the effect of proximity to villages and habitat vegetation (normalized difference vegetation index, NDVI) on the probability of space use by the tabby morph compared to the others. NDVI had a positive effect on site use in both morphs, but non‐tabby cats had a 2.1 higher probability of using the near sites than the far sites, independent of NDVI. The wild‐type tabby cats' probability of site use were equally likely to be unaffected by proximity, or have an interaction of proximity with NDVI whereby the far transects are used with increasing probability in sites of denser vegetation. We hypothesize that the camouflage of tabby cats, more than other colors and patterns, confers an advantage in roaming the woodland habitats for which this pattern evolved. This has both theoretical implications as rare empirical evidence of the adaptive value of fur coloration, and practical implications on managing the ecological impact of feral cats worldwide.

Soil microbial community composition and functions are disrupted by fire and land use in a Mediterranean woodland

The intersection of fire, land use transformations, and climate change is putting Mediterranean climate-type ecosystems at risk of soil degradation and loss of ecosystem services. Ondik et al. (2022b) showed that in a Mediterranean dry sclerophyll woodland of South Australia, high severity fire and clearing and grazing practices impacted both physicochemical and biological soil quality indicators. Building upon the work of Ondik et al. (2022b) this study aims to 1) identify soil physicochemical properties impacted by fire and land management that are indirect drivers of changes to soil microbial community composition and 2) determine whether the observed changes to soil microbial community composition affect soil microbial functions. Via a redundancy analysis, we identified fire and management-induced changes to pH, soil water repellency, nutrient stoichiometry, and total nutrient content as significant drivers of the composition of soil microbial communities. We then measured basal respiration, substrate induced respiration, and the carbon mineralisation quotient, and calculated functional trait distributions among microbial communities by linking 16S and 18S rRNA sequences to respiration modes and functional guilds, respectively. We found that fire reduced soil microbial respiration and the relative abundance (RA) of microbial symbionts, anaerobic bacteria, and microaerophilic bacteria, while increasing the RA of aerobic bacteria. Furthermore, management increased the RA of post-fire ectomycorrhizal fungi and may have reduced pathogenic load, microbial efficiency, and wood saprotrophs, while increasing litter, soil, and other saprotrophic species that are adapted to grasslands. This study shows that, through changes to microbial community composition, high severity wildfire and land management affected soil respiration rates, bacterial modes of respiration, prevalence of symbiotic bacteria and fungi, and microbial substrate preference. Having identified the main physicochemical drivers of changes to microbial community composition, we provide valuable insights into how fire and land management can impact soils in Mediterranean woodland.

Detection of goat herding impact on vegetation cover change using multi-season, multi-herd tracking and satellite imagery

The frequency and severity of Mediterranean forest fires are expected to worsen as climate change progresses, heightening the need to evaluate understory fuel management strategies as rigorously as possible. Prescribed small-ruminant foraging is considered a sustainable, cost-effective strategy, but demonstrating a link between animal presence and vegetation change is challenging. This study tested whether the effect of small-ruminant herd presence in Mediterranean woodlands can be detected by integrating remote sensing and herd tracking at the landscape scale. The daily foraging routes of seven shepherded goat herds that exploited a 100-km2 forested area of the Judean Hills, Israel, were tracked over six years using GPS (Global Positioning System) collars. Herd locations were converted to stocking rates, with units of animal-presence-days per unit area per defined time period, and mapped at a spatial resolution of 10 m. We estimated pixel-level vegetation cover change based on a time series of 63 monthly Landsat-8 images expressed as the normalized soil-adjusted vegetation index (SAVI). Spatiotemporal trend analysis assessed the magnitude and direction of change, and a random forest machine-learning algorithm estimated the relative impact on vegetation cover change of environmental factors as well as the herd-related factors of stocking rate that accrued over six years and distance to the closest corral. The last two factors were among the most influential factors determining vegetation cover change in the regional and individual-herd analyses. In some respects, the permanent herds differed in their spatial pattern of stocking rate from the mobile herds that periodically relocated their night corral throughout the year, but stocking rate scaled logarithmically for all herds individually and combined. The combination of multi-season GPS tracking, remote sensing, and machine-learning techniques, applied at a regional scale, detected herd impacts on vegetation cover trends, consistent with livestock foraging being an effective tool for fuel reduction in Mediterranean woodlands.

Interaction Networks Help to Infer the Vulnerability of the Saproxylic Beetle Communities That Inhabit Tree Hollows in Mediterranean Forests

Insect communities are facing contrasting responses due to global change. However, knowledge on impacts of communities' reorganizations is scarce. Network approaches could help to envision community changes in different environmental scenarios. Saproxylic beetles were selected to examine long-term variations in insect interaction/diversity patterns and their vulnerability to global change. We evaluated interannual differences in network patterns in the tree hollow-saproxylic beetle interaction using absolute samplings over an 11-year interval in three Mediterranean woodland types. We explored saproxylic communities' vulnerability to microhabitat loss via simulated extinctions and by recreating threat scenarios based on decreasing microhabitat suitability. Although temporal diversity patterns varied between woodland types, network descriptors showed an interaction decline. The temporal beta-diversity of interactions depended more on interaction than on species turnover. Interaction and diversity temporal shifts promoted less specialized and more vulnerable networks, which is particularly worrisome in the riparian woodland. Network procedures evidenced that saproxylic communities are more vulnerable today than 11 years ago irrespective of whether species richness increased or decreased, and the situation could worsen in the future depending on tree hollow suitability. Network approaches were useful for predicting saproxylic communities' vulnerability across temporal scenarios and, thus, for providing valuable information for management and conservation programs.

The effect of tree decline over soil water content largely controls soil respiration dynamics in a Mediterranean woodland

The effect of tree decline over soil water content largely controls soil respiration dynamics in a Mediterranean woodland

Tree-size heterogeneity modulates the forest age-dependent carbon density in biomass and top soil stocks on Mediterranean woodlands

AimsCarbon accumulation in terrestrial ecosystems is inherent to the vegetation development and ageing process. Primary productivity synthetize biomass which is constantly incorporated to soil. Vegetation community composition, and other ecological drivers, are known to mediate biomass production. However, links between forest developmental stage and ecological drivers of carbon stocks are unexplored. We address this topic under the prediction that species-rich and uneven-sized forests can improve carbon storage potential in biomass and topsoil fraction across its development.MethodsThe study was carried in forest stands growing under Mediterranean conditions in Central Spain. Carbon content in both above- and below-ground tree biomass and in topsoil organic matter (0–40 cm) was measured in 30 sampling plots of variable size (900–3000 m2). We also assessed Shannon species diversity index, Gini tree-size inequality index and forest developmental stage using dendrochronological procedures to derive the mean age of the oldest trees. First-order interaction terms between diversity factors and forest age were regressed against carbon density in compartment-independent regressions.ResultsForest-age and tree-size heterogeneity coupling was the main factor driving carbon density of both compartments. The interaction showed that woodlands maximize density in aged forests composed by uneven-sized trees. Models gave not support to consider species diversity as a mediator of carbon stocks.ConclusionOur results shed light on how tree-size heterogeneity can regulate the temporal dimension of forest ageing to rise the carbon storage potential. Mature forests in semi-arid environments cannot store carbon due to their intrinsic ontogeny, they need to grow structurally diverse.

Habitat-dependent breeding biology of the Blue Tit (Cyanistes caeruleus) across a continuous and heterogeneous Mediterranean woodland

Mediterranean woodland environments are characterised by high spatial and temporal heterogeneity, which means the inhabiting species face a wide variety of selective pressures. Species may respond differently to habitat heterogeneity and so distinct eco-evolutionary scenarios may be responsible for the inter-habitat variability in reproductive strategies observed in certain species. The inter-forest variability of some reproductive traits in passerines has been examined by comparing forest patches or separated fragments. However, there is still little information regarding how such highly mobile animals adjust their breeding performance across continuous and heterogeneous woodlands. Here we studied the reproductive performance of a population of Blue Tits (Cyanistes caeruleus) in an area of continuous Mediterranean woodland that included two mountain slopes and four different types of forest, ranging from deciduous oak forests to perennial non-oak forests. We studied the habitat heterogeneity and inter-forest phenotypic variation in terms of reproductive performance and adult and nestling biometry, besides also exploring the effects of ectoparasites on Blue Tit reproduction. Eggs were laid earliest in deciduous Pyrenean Oak (Quercus pyrenaica) forests, while clutch size and the number of fledglings were highest in the humid Pyrenean Oak forest, which had the greatest tree coverage and most humid climate, and lowest in the coniferous Scots Pine (Pinus sylvestris) forest. There were no inter-forest differences in hatching (percentage of nests with at least one egg hatched) and fledging (percentage of nests in which at least one nestling fledged) success. Similarly, there were no inter-forest differences in adult and nestling biometry, but adults that raised more fledglings had a lower body mass, while males whose females laid larger clutches had smaller tarsi. Most ectoparasites did not affect Blue Tit reproduction, although Culicoides had a negative impact on nestling body mass. These results suggest that Blue Tits can adjust their reproductive effort to the forest where they breed even across a very small spatial scale. Different eco-evolutionary scenarios, such as phenotypic plasticity or genetic structuring and local adaptation, might explain the phenotypic differentiation in the reproductive strategies observed over small areas in woodlands.

Vegetation strategies for nitrogen and potassium acquisition along a climate and vegetation gradient: From semi-desert to temperate rainforest

Nutrient acquisition strategies of plants regulate water flow and mass transport within ecosystems, shaping earth surface processes. Understanding plant strategies under current conditions is important to assess and predict responses of natural ecosystems to future climate and environmental changes. Nitrogen (N) and potassium (K) (re-)utilization from topsoil and their acquisition from subsoil and saprolite were evaluated in a continental transect, encompassing three study sites – an arid shrubland, a mediterranean woodland, and a temperate rainforest – on similar granitoid parent material in the Chilean Coastal Cordillera. The short-term (<1 year) plant N and K acquisition was traced with 15N and the K analogs rubidium and cesium. To do so, the tracers were either injected into topsoil, subsoil, or saprolite, in the immediate vicinity of eight individual plants per study site and injection depth. The long-term (>decades) K uplift by plants was investigated by the vertical distribution of exchangeable K+ and Na+. Recoveries of 15N and K analogs by arid shrubland plants were similar from topsoil, subsoil, and saprolite. Mediterranean woodland shrubs recovered the tracers primarily from topsoil (i.e., 89 % of recovered 15N and 84 % of recovered K analogs). Forest plants recovered the tracers from topsoil (15N = 49 %, K analogs = 57 %) and partially from greater depth: 38 % of recovered 15N and 43 % of recovered K analogs were acquired from subsoil and saprolite, respectively. Low nutrient accessibility in the topsoil (e.g., because of frequent droughts) drives shrubland plants to expand their N and K uptake to deeper and moister soil and saprolite. Woodland and forest plants dominantly recycled nutrients from topsoil. In the forest, this strategy was complemented by short-term uplift of N and K from depth. The vertical distribution of exchangeable K indicated long-term uplift of K by roots in all three sites. This highlighted that long-term K uplift from depth complements the nutrient budget across the continental transect.

Estimation of Grazing Activity of Dairy Goats Using Accelerometers and Global Positioning System.

The recent development of advanced electronic sensors to monitor and record animal grazing activity provides a real opportunity to facilitate understanding of their behavioral responses. This study aimed to characterize the grazing activity and protein–energy requirements of grazing dairy goats in a Mediterranean woodland in northern Morocco by combining two sensors, the Global Positioning System (GPS) and three axis accelerometers. An experiment was conducted in a representative woodland with eight dairy goats. Measurements were undertaken during the three main grazing seasons (spring, summer, and autumn) for two consecutive and contrasting years. Grazing activity parameters were assessed using GPS collars and leg position sensors. The results showed that grazing time was higher in spring (57% and 59%) than in summer (39% and 36%) and autumn (41% and 45%), respectively, for the dry and wet years (p < 0.001). During the two studied years, the daily horizontal distance traveled by the goats increased from spring (about 4.5 km) to summer (about 6.5 km) and autumn (about 7.4 km), while greater daily vertical distances were recorded over similar distances during summer–autumn. Several protein–energy intakes that were insufficient to cover the requirements of the grazing goats were recorded, especially in summer. The combination of GPS collars and accelerometers contributed to a better understanding of the grazing activities of dairy goats in the studied Mediterranean woodland. These findings provide useful data on the protein–energy balances of dairy goats and offer additional information that could be useful for herders and managers to enhance goat-feeding strategies and guarantee high-performance in the semi-extensive traditional goat farming system.

Palynological investigations in the Orce Archaeological Zone, Early Pleistocene of Southern Spain

Palynological investigations in the Orce Archaeological Zone (OAZ) (Guadix-Baza Basin, Granada, Spain), Venta Micena 1 (VM1), Barranco León (BL) and Fuente Nueva 3 (FN3) are presented. This archaeological region is connected with the first Homo populations in Western Eurasia during the Early Pleistocene. The VM1 pollen record is characterized by Ephedra, and to a lesser extent, Pinus, Juniperus and evergreen Quercus, occassionally accompanied by Olea, Genisteae, Erica, deciduous Quercus, Alnus, Castanea, Fraxinus, Salix and Phillyrea. BL is dominated by Juniperus, Olea, Pinus, Poaceae, and evergreen Quercus. FN3 is characterized by an open Mediterranean woodland dominated by evergreen Quercus, Pinus, Juniperus and Olea, accompanied by deciduous Quercus, Castanea, Populus, Salix, Ulmus, Fraxinus, Pistacia, Phillyrea, Genisteae, Erica, Cistus, and Ephedra fragilis. Relic Tertiary taxa in OAZ include Carya, Pterocarya, Eucommia, Zelkova, and Juglans. The Early Pleistocene OAZ vegetation is a mosaic of different landscapes embracing mesophytes, thermophytes, xerophytes, xerothermophytes, and Mediterranean elements. These finds are compared with former pollen analyses in the region and beyond within the Iberian Peninsula.

Soil VOC emissions of a Mediterranean woodland are sensitive to shrub invasion.

Many belowground processes, such as soil respiration and soil-atmosphere VOC (volatile organic compounds) exchange, are closely linked to soil microbiological processes. However, little is known about how changes in plant species cover, i.e. after plant invasion, alter these soil processes. In particular, the response of soil VOC emissions to plant invasion is not well understood. We analysed soil VOC emissions and soil respiration of a Mediterranean cork oak (Quercus suber) ecosystem, comparing soil VOC emissions from a non-invaded Q. suber woodland to one invaded by the shrub Cistus ladanifer. Soil VOC emissions were determined under controlled conditions using online proton-transfer time-of-flight mass spectrometry. Net soil VOC emissions were measured by exposing soils with or without litter to different temperature and soil moisture conditions. Soil VOC emissions were sensitive to C. ladanifer invasion. Highest net emission rates were determined for oxygenated VOC (acetaldehyde, acetone, methanol, acetic acid), and high temperatures enhanced total VOC emissions. Invasion affected the relative contribution of various VOC. Methanol and acetaldehyde were emitted exclusively from litter and were associated with the non-invaded sites. In contrast, acetone emissions increased in response to shrub presence. Interestingly, low soil moisture enhanced the effect of shrub invasion on VOC emissions. Our results indicate that shrub invasion substantially influences important belowground processes in cork oak ecosystems, in particular soil VOC emissions. High soil moisture is suggested to diminish the invasion effect through a moisture-induced increase in microbial decomposition rates of soil VOC.