Longer summer seasons after fire induce permanent drought legacy effects on Mediterranean plant communities dominated by obligate seeders.

The ecological stability of Mediterranean ecosystems is being threatened by climate change. One of the impacts that is expected to be aggravated is the effect of summer drought prolongation toward previous or subsequent seasons by becoming more frequent. This, along with wildfires, could trigger synergistic negative effects on ecosystem regeneration capacity. Here we assessed how extending summer drought in two different ways (to autumn, AutExcl treatment, or bringing it forward to the following spring, SprExcl treatment) would affect plant recovery after an experimental fire carried out in summer in a Mediterranean seeder community. By installing rainout shelters, we assessed differences in seedling emergence, survival and establishment in the main families (Cistaceae, Labiatae, Leguminosae), and the effect on species richness and community composition. We observed that these post-fire dry season extensions reduced the total number of established seedlings and species richness. The most impacting drought treatment was AutExcl. However, the regeneration response was variable depending on the studied family. SprExcl was also determinant for Labiate survival rates. These results suggest that drought events which prolong the usual summer season may have a permanent drought legacy effect on seeder communities as practically all the seeder species populations were established in the first post-fire year. This fact is relevant for Mediterranean ecosystems dominated by seeder species as severer and longer droughts are increasingly recorded and are expected to become more frequent in forthcoming decades.

Adaptive flammability syndromes in thermo-Mediterranean vegetation, captured by alternative resource-use strategies.

Fire affects and is affected by leaf functional traits indicative of resource allocation trade-offs. Global change drivers constrain both the resource-use strategies and flammability of coexisting species. However, small attention has been given in identifying links among flammability and plant economics. Ambiguity comes from the fact that flammability is a multidimensional trait. Different flammability attributes (i.e. ignitibility, sustainability, combustibility and consumability) have been used to classify species, but no widely-accepted relationships exist between attributes. We hypothesised that flammability is a spectrum (defined by its four attributes) and the alternative flammability syndromes of coexisting species can be captured by their resource-use strategies. Furthermore, we argue that flammability syndromes are adaptive strategies that ensure persistence in the post-fire community. We conducted a large-scale study to estimate all flammability attributes on leaves from nine, dominant, thermo-Mediterranean species with alternative resource-use and fire-response strategies across a wide environmental and geographic gradient. We assessed the interdependence among attributes, and their variation across ecological scales (genus, species, individual, site and region). Furthermore, we collected 10 leaf functional traits, conducted a soil study and extracted long-term climatological data to quantify their effect on flammability attributes. We found that leaf flammability in thermo-Mediterranean vegetation is a continuous two-dimensional spectrum. The first dimension, driven by leaf shape and size, represents heat release rate (combustibility vs. sustainability), while the second, controlled by leaf economics, presents ignition delay and total heat release (i.e. consumability). Alternative flammability syndromes can increase fitness in fire-prone communities by offering qualitative differences in survival or reproduction. Trade-offs and constraints that control the distribution of resource-use strategies across environmental gradients appeared to drive leaf flammability syndromes as well. Tying the flammability spectrum with resource allocation trade-offs on a global scale can help us predict future ecosystem properties and fire regimes and illustrate evolutionary constraints on flammability.

Increased aridity drives post-fire recovery of Mediterranean forests towards open shrublands.

Recent observations suggest that repeated fires could drive Mediterranean forests to shrublands, hosting flammable vegetation that regrows quickly after fire. This feedback supposedly favours shrubland persistence and may be strengthened in the future by predicted increased aridity. An assessment was made of how fires and aridity in combination modulated the dynamics of Mediterranean ecosystems and whether the feedback could be strong enough to maintain shrubland as an alternative stable state to forest. A model was developed for vegetation dynamics, including stochastic fires and different plant fire-responses. Parameters were calibrated using observational data from a period up to 100 yr ago, from 77 sites with and without fires in Southeast Spain and Southern France. The forest state was resilient to the separate impact of fires and increased aridity. However, water stress could convert forests into open shrublands by hampering post-fire recovery, with a possible tipping point at intermediate aridity. Projected increases in aridity may reduce the resilience of Mediterranean forests against fires and drive post-fire ecosystem dynamics toward open shrubland. The main effect of increased aridity is the limitation of post-fire recovery. Including plant fire-responses is thus fundamental when modelling the fate of Mediterranean-type vegetation under climate-change scenarios.

Filtration system performance cleaning exhaust air of pneumatic maize seed drills.

BACKGROUND: In the agricultural sector, toxic substances can be released into the atmosphere. In recent years, Europe has encountered a significant environmental issue related to the dispersion of pesticides during maize seeding, especially when performed with pneumatic seed drills. This phenomenon can be very dangerous for insects, as the dispersed dust contains pesticides (insecticides, fungicides, etc.) used to dress maize seeds. On the basis of these considerations, experimental tests have been carried out using a filtration system to clean the airflow that exits from the fan of pneumatic maize seed drills. RESULTS: The tested filtration system does not interfere with the seeding quality because the vacuum level observed within the filtration system assembled on the seeder (5.7 kPa) is 27% higher than the correct vacuum level to guarantee good seeding quality (4.2 kPa). In addition, it enables a reduction in the risk of environmental contamination, as no dust deposits were found at different distances from the machine. CONCLUSION: The use of a filtration system shows advantages in terms of environmental and operator safety because dangerous materials are contained in the filter case, thus avoiding contamination of neighbouring areas and the machinery used (tractor and seed drill). © 2015 Society of Chemical Industry.

Fire management, managed relocation, and land conservation options for long-lived obligate seeding plants under global changes in climate, urbanization, and fire regime.

Most species face multiple anthropogenic disruptions. Few studies have quantified the cumulative influence of multiple threats on species of conservation concern, and far fewer have quantified the potential relative value of multiple conservation interventions in light of these threats. We linked spatial distribution and population viability models to explore conservation interventions under projected climate change, urbanization, and changes in fire regime on a long-lived obligate seeding plant species sensitive to high fire frequencies, a dominant plant functional type in many fire-prone ecosystems, including the biodiversity hotspots of Mediterranean-type ecosystems. First, we investigated the relative risk of population decline for plant populations in landscapes with and without land protection under an existing habitat conservation plan. Second, we modeled the effectiveness of relocating both seedlings and seeds from a large patch with predicted declines in habitat area to 2 unoccupied recipient patches with increasing habitat area under 2 projected climate change scenarios. Finally, we modeled 8 fire return intervals (FRIs) approximating the outcomes of different management strategies that effectively control fire frequency. Invariably, long-lived obligate seeding populations remained viable only when FRIs were maintained at or above a minimum level. Land conservation and seedling relocation efforts lessened the impact of climate change and land-use change on obligate seeding populations to differing degrees depending on the climate change scenario, but neither of these efforts was as generally effective as frequent translocation of seeds. While none of the modeled strategies fully compensated for the effects of land-use and climate change, an integrative approach managing multiple threats may diminish population declines for species in complex landscapes. Conservation plans designed to mitigate the impacts of a single threat are likely to fail if additional threats are ignored.

Análise tridimensional de esforços em elementos rompedores de semeadoras de plantio direto / Tridimentional efforts analyses of furrow opening in no tillage seeder

As informações da avaliação de mecanismos de abertura de sulco de semeadoras de plantio direto auxiliam as empresas no dimensionamento de ferramentas rompedoras do solo, que buscam menor requerimento energético. Este trabalho foi realizado num solo classificado como Latossolo Vermelho com o objetivo de avaliar tridimensionalmente os esforços dos mecanismos de abertura de sulco de semeadoras adubadoras de plantio direto. O delineamento experimental utilizado foi o de blocos ao acaso com cinco tratamentos, sendo cinco mecanismos de abertura de sulco (disco liso - DL, disco corrugado - DC, disco ondulado - DO, disco duplo - DD e haste sulcadora - H). Para mensurar os esforços dos mecanismos de abertura de sulco, foi utilizado um dinamômetro com sensibilidade nas direções horizontal, transversal e vertical e no momento fletor e torsor. A avaliação mostrou que a interação entre mecanismos de abertura de sulco e carga vertical não foi significativa, entretanto os fatores foram significativos quando analisados individualmente. O resultado individual dos mecanismos de abertura de sulco mostrou que o disco ondulado proporcionou maior área de mobilização do solo, a haste sulcadora apresentou o menor valor de força vertical e o disco duplo e a haste sulcadora obtiveram o menor esforço horizontal.

Information from evaluation mechanisms of opening furrows seedlings in no-tillage systems helps companies todesign tools soil, seeking for lower energy requirement. This work was achieved in a Red Latosol soil in order to evaluate dimensional efforts of mechanisms opening furrows. The experimental design used was a complete randomized block with 5 projects and five mechanisms of furrow opening (even disk - DL, corrugated disk - DC, ondulated disk - DO, double disk - DD and furrow rod - H). To measure forces, a dynamometer with sensitivity in draught, transverse and vertical directions and torsor e fletor moment were used. The strength need to be consider in individual results of opening mechanisms furrows in tools designed for seeders The rod needs little effort to penetrate the vertical soil due to the suction. The ondulated disk provides greater mobilization of soil due to the project design of the tool.