Erika Buscardo

Impact of wildfire return interval on the ectomycorrhizal resistant propagules communities of a Mediterranean open forest

Ectomycorrhizal (ECM) fungi, in particular their spores and other resistant propagules, play an important role in secondary succession processes that facilitate regeneration after disturbance events. In this study, the effects of high and low wildfire frequencies (respectively short and long fire return intervals) on the resistant propagules communities (RPCs) of a Mediterranean open pine forest were compared. Soil samples were collected in four mountain sites with different fire return intervals and used to test ectomycorrhiza development in two hosts, Pinus pinaster and Quercus suber. RPCs were characterized by direct sequencing of fungal internal transcribed spacer (ITS) regions from individual ECM root tips. Eighteen ECM species were detected in the bioassay. The most frequently found fungi were Cenococcum geophilum, Inocybe jacobi, Thelephora terrestris, Tomentella ellisii on both hosts and Rhizopogon luteolus and R. roseolus on maritime pine. A short fire return interval reduced the species richness of the ECM community found on Q. suber, promoted species like R. roseolus and reduced the abundance of other species (e.g. R. luteolus). The abundance of I. jacobi was positively affected by long fire return interval, but decreased significantly with recurrent fires. These results indicate that changes in fire frequency can alter the structure, composition and diversity of ECM communities, which could compromise the resilience of the ecosystem in highly disturbed areas.

Edible Invertebrates Among Amazonian Indians: A Critical Review of Disappearing Knowledge

For the indigenous populations of Amazonia, invertebrates constitute an important component of the diet. We have information on entomophagy for 39 ethnic groups, about 21,4 per cent of the 182 groups known in the Amazon Basin, but the use of this non conventional food resource is probably much more widespread. We present here a data-base of all the information available for each ethnic group regarding the species included in the diet, the scientific and the ethno name if known, the stage of life-cycle consumed, the manner of preparation and, when known, the host plant. This data-base lists 115 species scientifically identified and 131 ethno names. In addition, we have information about other 384 ethno names, with unsecure link to the Linnean taxonomy suggesting that local knowledge is very extensive. The data-base represents not only an easy to consult resource, but also a support for further research. The knowledge of the relations between indigenous populations and ecosystem is indeed the base for the natural and cultural biodiversity preservation.

Recovery Potential of Dune Ecosystems Invaded by an Exotic Acacia Species (Acacia longifolia)1

Abstract The effect of mechanical clearing and litter removal on control of Sydney golden wattle was studied in areas of Portugal that had been invaded for either long or short periods. The plant species that emerged and soil parameters were monitored to assess the recovery potential and the soil status of these areas after Sydney golden wattle control. More plant species emerged in the plots where mechanical control in combination with litter removal was applied than in nontreated plots or in plots where mechanical control alone was used. More plant species emerged in the recently invaded areas than in those that had been invaded for a long time. More Sydney golden wattle seedlings were found in the long-invaded area than in the recently invaded one. Total litter, nitrogen and carbon content, and β-glucosaminidase activity were higher in the soil of the long-invaded compared with the recently invaded areas. Regarding the efficacy of the methods used to remove Sydney golden wattle, sprouting was not observed 10 mo after cutting the trees in both areas, although this was not the case in other parallel studies. Nomenclature: Sydney golden wattle, Acacia longifolia (Andrews) Willd. Additional index words: Invasive plants, mechanical control, native species recovery, soil properties. Abbreviations: A, with Acacia longifolia; AR, Acacia longifolia removed; ALR, Acacia longifolia and litter removed; NAG, N-acetyl-β-d-glucosaminidase (NAGase EC 3.2.1.30); NRSJD, Natural Reserve of São Jacinto Dunes.

NUTRIENT CONTENT OF TERMITES (SYNTERMES SOLDIERS) CONSUMED BY MAKIRITARE AMERINDIANS OF THE ALTO ORINOCO OF VENEZUELA

Termites seri (especially Syntermes aculeosus soldiers) are collected extensively by Makiritare (or Ye Kuana Indians in the Alto Orinoco) and consumed raw or after soaking in hot water (60 -80 C). They are gathered be means of termite fishing technique and then transported into a package called kukuruciu made with Musacean (Phenakospermum sp.) leaves. The solders of Syntermes constitute a food source of great nutritional value: high in proteins and essential amino acids such as trytophan, which is generally limiting in the food insects. Abundant are minerals such as iron and calcium together with micronutrients. Essential fatty acids are well represented. In general, heads of seri are better nutritionally featured than thorax and abdomens (not eaten by the Makiritare but comsumed by the Piaroa Indians).

Common environmental factors explain both ectomycorrhizal species diversity and pine regeneration variability in a post-fire Mediterranean forest

Natural seedling regeneration and establishment after stand replacing wildfires is influenced by a series of environmental and biological constraints. In this study, we characterized the diversity and structure of the ectomycorrhizal (ECM) fungal community associated with post-fire naturally regenerated maritime pine saplings, and individuate the environmental factors responsible for fungal species distribution. We also identify the main environmental factors responsible for maritime pine regeneration variability and assessed the relation between saplings performance and ECM fungal diversity indices. Fungal species were identified by direct sequencing of internal transcribed spacer regions. Five years after the disturbance event, a total of 30 taxa colonized the pine saplings. The ECM fungal community was dominated by ruderal species of the genus Rhizopogon (present in almost half of the samples). Almost one third of the identified ECM fungal species belonged to the family Thelephoraceae. Typical k-selected species like Amanita pantherina, Boletus aestivalis, Lactarius chrysorrheus, and Russula densifolia were found on pine saplings collected in proximity of unburnt pine trees, in correspondence with low erosion extents. Pine regeneration varied throughout the study areas and was enhanced at higher elevations, in correspondence with moderate slopes, shallower soils, and a reduced cover of ericaceous shrubs and bare ground. These conditions were found in close proximity to patches of pine trees that survived the disturbance event and were previously characterized by a higher pre-fire pine biomass. Even though no correlations were found between saplings performance and ECM fungal diversity indices, common environmental factors (i.e., ericaceous shrub cover, extent of erosion, slope, and soil depth) were responsible for shaping the ECM fungal distribution and for describing most of the explained regeneration variability.

Effect of root age on the allocation of metals, amino acids and sugars in different cell fractions of the perennial grass Paspalum notatum (bahiagrass)

This work aimed to compare the allocation of Al, Fe, Cu, Ni, amino acids and sugars in different fractions of root cells of Paspalum notatum with 21 and 120 days old grown in quartz sand. In general younger roots showed a higher content of Al, Fe, Cu Ni, amino acids and sugars, compared to older roots. This can be due to a higher metabolic activity of younger roots and/or to structural changes that can occur with cell ageing. Al and Fe were mainly allocated to fractions with pectin, hemicellulose and cellulose, both in younger and older roots. However, older roots also showed a significant fraction of Al allocated to the intracellular fraction. It seems that older roots were less able to prevent the entry of Al in the cytoplasm. The proportion of Cu was higher in intracellular components, both in younger and older roots, as expected from an essential nutrient. Ni content was very low in older roots and in younger roots it was mainly allocated to the intracellular fraction and to the cell wall polysaccharides fraction. The amino acids were mainly allocated to the cytoplasm and polysaccharide fraction. Although younger roots showed a higher total amount of amino acids compared to older roots, the amino acids profile and allocation, mainly in the cytoplasm polysaccharides, was quite similar. Arabinose, a major component of structural glycoproteins of the primary cell wall matrix, was only detected in younger roots. Thus, it seems that root cells of P. notatum suffered changes in the composition of the cell wall components with ageing. To further understand the structural changes of root cells with ageing and its effect on metal allocation, it is important to quantify several components of the cell wall matrix, namely pectins and glycoproteins.

The Biogeochemistry of the Main Forest Vegetation Types in Amazonia

The structure and functioning of natural ecosystems reflect spatial and temporal characteristics of the atmosphere, physiography (geology, topo-hydro-pedo sequences), and biodiversity (vegetation type and associated fauna). Exchanges of gases, water, and organic and inorganic compounds between atmosphere and biosphere (vegetation, soil) strongly contribute to biogeochemical phenomena in Amazonia and to atmospheric phenomena within and outside of Amazonia. Some of these exchanges have importance for cloud formation and rainfall, while others (carbonic and trace gases) contribute to carbon sequestration/greenhouse effects. The Amazon basin encompasses diverse combinations of climate, soil, and hydrology that result in a variety of vegetation types. The current state of knowledge on Amazonian regional biochemistry is mainly based on studies carried out in terra firme type ‘lowland evergreen rainforest’, with a focus on the carbon cycle. For a better understanding of the biogeochemical functioning of the Amazon basin, attention to physiography and its relationship, including feedback mechanism, with vegetation diversity at the landscape scale is needed. This chapter synthesises patterns in biogeochemistry of the main vegetation formations of the Amazon basin. The objective is to demonstrate differences in elemental cycles (stock and fluxes) among the main vegetation formations. The patterns of fixation, storage, and use of nutrients for biomass production, the patterns of internal (re)cycling (leaching of crown nutrients, litterfall, root growth and death) within the main forest types, and the patterns of litter decomposition and soil processes (nutrient availability, nitrogen mineralisation vs. immobilisation) and gas emissions from soil are discussed.