Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a ...unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.
Chronic decline and Sudden death are two syndromes of cork oak (
Quercus suber
) dieback. Mortality is associated with water stress, but underlying physiological mechanisms are poorly understood. ...Here, we investigated the physiological performance of declining trees during the summer drought. Leaf water potential, gas-exchange, fluorescence of photosystem II and leaf and root starch concentration were compared in healthy (asymptomatic) and declining trees. Low annual cork increment in declining trees indicated tree decline for several years. All trees showed similar water status in spring. In summer, declining trees showed lower predawn leaf water potential (−2.0 vs. −0.8 MPa), but unexpectedly higher midday leaf water potential than healthy trees (−2.8 vs. −3.3 MPa). The higher midday water potential was linked to by means of strongly reduced stomatal conductance and, consequently, transpiration. This study is pioneer showing that declining trees had high midday water potential. A tendency for lower sap flow driving force (the difference between predawn and midday water potential) in declining trees was also associated with reduced photosynthesis, suggesting that chronic dieback may be associated with low carbon uptake. However, starch in roots and leaves was very low and not correlated to the health status of trees. Declining trees showed lower water-use efficiency and non-photochemical quenching in summer, indicating less resistance to drought. Contrarily to chronic decline, one tree that underwent sudden death presented predawn leaf water potential below the cavitation threshold.
Mortality events in cork and holm oaks have occurred in the Mediterranean basin since the beginning of the XX century, but severity of decline increased during the 1980s. By that time, the exotic ...soil borne pathogen
Phytophthora cinnamomi
was often recovered from declining stands and since then it has been considered the main factor associated with decline. This work analyses data concerning
P. cinnamomi
surveys in cork and holm oaks trees, pathogenicity tests carried out in controlled experiments, studies about the influence of site characteristics in tree decline and approaches to control the disease. Results of field surveys showed that the pathogen is widespread and pathogenicity tests suggested that host susceptibility to the pathogen is moderate when seedlings are in appropriate watering conditions, particularly cork oaks. Occurrence of decline is also associated with soil characteristics that interfere with root expansion and water retention. We assessed the relative importance of each factor involved in decline and revised the role of
P. cinnamomi
in cork and holm oak decline.
Widespread events of cork oak mortality are disturbing the system and jeopardizing cork production. This research combined techniques to analyze in detail these events on a small scale. To understand ...the dynamics of cork oak mortality and the factors associated with it, a diachronic study was performed in two farms located in Évora, Portugal. The case studies were two nearby farms suffering from tree dieback since 2000. Aerial images of the area, taken in 2004 and 2012, were processed with GIS in order to detect dead trees and to calculate tree crown cover. Slope and aspect were obtained through cartographic and topographic maps. The intersection of those maps resulted in polygons with unique values for those characteristics. Mortality index and tree crown cover were calculated for each one of them. Maps of the kernel density of tree mortality were generated to select key spots for pests and diseases field survey. Detection of soil pathogens was performed using baiting method and molecular analyses. The analysis showed that both farms had the same predisposing and inciting factors associated with tree decline, such as the soilborne Phytophthora cinnamomi, sunlight exposure or soil disking. However, the relative importance of each factor varied among farms. As a result, the dieback processes also differed, despite their similarity regarding mortality intensity. The diachronic approach associated with field survey resulted in a better comprehension of the tree dieback on a small scale and proved its usefulness in future decision-making regarding tree mortality mitigation.
The bark of cork oak (Quercus suber L.) is mostly used for cork stopper production; when bark undergoes a series of industrial procedures, boiling usually leads to changes in the characteristics of ...its tissue. Trees are traditionally grown under natural conditions; however, irrigation is now being used in plantations. This permanent water availability affects cork oak development, while its effects on industrial procedures are unknown. This study provides the first insight into the behaviour of the cell walls of cork during the process of swelling and boiling when trees have been grown under irrigation, that is, subject to a specific water regime. Cork tissue is analysed using environmental and scanning electron microscopy under three regimes: raw conditions, following immersion in water, and after boiling. Additionally, the radial expansion of samples is determined. The results show greater cell wall expansion in cork from the irrigated site than in cork from the traditional rainfed plot when hydrated for 24 h. After boiling, the cell walls of the cork from the rainfed site are thinner than in the raw stage, which is in contrast to the irrigated cork. This study suggests that irrigation during cork oak growth produces a higher capacity for adsorption, increasing cell wall thickness from the raw stage to the boiling stage.
The sustainability of forest species is directly related to the success of stand regeneration. Assuring success is particularly critical in stands where perpetuity relies on natural regeneration, as ...is often the case with cork oak forests. However, 59% of the stand in Portugal have no natural regeneration, and climate change could further worsen the sustainability of the system. The study summarizes the factors that affect the natural regeneration of cork oak ( Quercus suber L.) based on current knowledge and presents a case study on a forest in Northeast Portugal, where the natural regeneration of Quercus suber under the effect of climate change have been monitored and analyzed. The present work focuses on the effect of stand density, i.e., tree cover, on the production of acorns, the establishment and survival of seedlings, and the impact of the summer season on seedling mortality. The monitoring was carried out in February, June, September 2022, and January 2023 in two stands with distinct stand canopy cover, when the region was under extreme drought. Data analysis was performed using the analysis of variance for repeated measures and the Mann–Whitney-Wilcoxon test. The study showed that cork oak regeneration is influenced by stand density, which promoted the establishment success and survival of natural regeneration in a period of reduced precipitation, despite possible competition for water resources. The mean number of seedlings differed significantly between the two stands. However, there were no significant differences in the mean number of seedlings throughout the field measurements. Additionally, the percentage of dead seedlings was low even after the summer season (9.5% of the total seedlings) in the denser stand. These results indicate that high canopy cover can have a protective effect for extreme climatic events and should be considered in forestry management to promote regeneration of the cork oak forests.
This study is the beginning of the first long-term study on cork oak irrigation under field conditions, with a structural-functional approach. Cork oaks are currently facing disturbances affecting ...cork quality and quantity, jeopardizing the future of the economic sector. There is a need for new production techniques that maximize cork oak growth and vitality. In this study, irrigation was implemented in a new intensive cork oak plantations to test the best irrigation volume. The long-term goal is to improve tree growth with minimum water requirements. A 6 ha intensive plantation was installed in Coruche, Portugal. The experimental plot consisted of a subsurface drip fertigation system, buried 40 cm deep; with five independent irrigation treatments. It was tested four irrigation volumes during the dry period—21 weeks in the summer of 2016—ranging from 1.88 mm to 5.62 mm a week. Information on meteorological conditions, soil moisture profile and leaf stomatal conductance were gathered periodically and dendrometric measurements were performed before and after the treatments. Cork oaks’ structural and functional parameters were associated with irrigation volume Response to irrigation showed an inflection point in treatment 2, corresponding to a water supply of 3.12 mm per week: below the inflection point, stomatal conductance was reduced by 15% and relative diameter growth at the base was reduced by 10%. Stomatal conductance also showed a positive relationship with soil moisture below the irrigation tubes and with plants’ stem diameter. In conclusion, irrigation supply during the period of water stress improved function and structure of cork oaks seedlings under field conditions. These results suggest that irrigation can be a viable alternative to improve cork oak growth in afforestation and reforestation.
The goal of this study was to ascertain why the production of variable seediness is advantageous for Attalea phalerata palms. Our hypothesis was that variation reduces seed predation by the spiny ...rats Thrichomys pachyurus and Clyomys laticeps. Although there is a positive correlation between endocarp size and number of seeds, endocarps sometimes contain more or fewer seeds than expected; palms bluff about the number of seed per endocarp. Therefore, rats do not know how many seeds an endocarp contains. To model rats' predating behavior, we applied Charnov's Marginal Value Theorem. The model shows that rats attack endocarps only when the energy gain is higher than the energy available in the habitat. Hence, it is not advantageous to eat all the seeds inside an endocarp. This explains why 45 percent of forest endocarps and 35 percent of savanna endocarps were still viable after predation. We then applied the model to two simulated endocarp populations with less variability in the number of seeds per endocarp size and determined that viable diaspores after predation were reduced to 15 percent. With less variability, palms cannot bluff about the number of seeds inside endocarps and predators can predict accurately how many seeds they should try to eat. Uncertainty about the number of seeds diminished predation but gave selective advantage to multiseeded fruits. Therefore, the bluffing strategy would be evolutionarily stable only if it were counterbalanced by other forces. Otherwise, predators would win the bluffing game. Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp.
This study reports the effect of daily mean ambient temperature on daily activity and habitat use by the giant anteater (Myrmecophaga tridactyla) in the Pantanal wetlands of Brazil. We equipped 11 ...giant anteaters with a global position system collar programmed to acquire a location every 10 min for 15 d. A temperature data logger left in the meteorological station at the study site registered data on ambient temperature. Giant anteaters were mainly active in open fields except during the coldest days, when they sought protection inside forests. Giant anteaters also used open habitats for resting but during the hottest or chilliest days they sheltered in forests. In the Pantanal, where temperatures are usually high, giant anteaters were active all night long, but as daily average ambient temperature decreased anteaters began and finished activity progressively earlier and reduced total activity. As a consequence, time spent active at daylight increased progressively and time spent active during the night decreased progressively, probably to allow the anteaters to expose themselves to solar radiation and to avoid heat loss during the night. /// O objetivo deste trabalho foi relacionar a actividade e uso do habitat do tamanduá-bandeira (Myrmecophaga tridactyla) com as temperaturas médias diárias do Pantanal Brasileiro. Equipamos 11 tamanduás-bandeira com um sistema de posicionamento global (GPS) previamente programado para registrar uma localização cada 10 minutos durante 15 dias. Colocamos um registrador de temperatura na estação meteorológica da área de campo para registrar a temperatura ambiente a cada 10 minutos. A atividade dos tamanduás-bandeira ocorreu essencialmente em habitat descobertos, excepto durante os dias mais frios, onde também estiveram ativos em florestas. Para repouso, usaram também habitat descobertos, mas nos extremos de temperatura optaram por abrigo em áreas mais cobertas. Os tamanduás têm apenas um período de atividade por dia, cuja duração é reduzida com a diminuição da temperatura média diárias do ambiente. No Pantanal, geralmente com clima quente, os tamanduás-bandeira são noturnos mas, à medida que a temperatura média diária diminui, a sua atividade inicia-se e termina progressivamente mais cedo. Como conseqüência, à medida que os dias vão esfriando, os tamanduás-bandeira vão se tornando cada vez mais ativos durante o dia e menos ativos durante a noite, aumentando assim a sua exposição à radiação solar e evitando que emanem muito calor corporal durante a noite.
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