The regional variation of aboveground live biomass in old-growth Amazonian forests

The biomass of tropical forests plays an important role in the global carbon cycle, both as a dynamic reservoir of carbon, and as a source of carbon dioxide to the atmosphere in areas undergoing deforestation. However, the absolute magnitude and environmental determinants of tropical forest biomass are still poorly understood. Here, we present a new synthesis and interpolation of the basal area and aboveground live biomass of old‐growth lowland tropical forests across South America, based on data from 227 forest plots, many previously unpublished. Forest biomass was analyzed in terms of two uncorrelated factors: basal area and mean wood density. Basal area is strongly affected by local landscape factors, but is relatively invariant at regional scale in moist tropical forests, and declines significantly at the dry periphery of the forest zone. Mean wood density is inversely correlated with forest dynamics, being lower in the dynamic forests of western Amazonia and high in the slow‐growing forests of eastern Amazonia. The combination of these two factors results in biomass being highest in the moderately seasonal, slow growing forests of central Amazonia and the Guyanas (up to 350 Mg dry weight ha^?1) and declining to 200–250 Mg dry weight ha^?1 at the western, southern and eastern margins. Overall, we estimate the total aboveground live biomass of intact Amazonian rainforests (area 5.76 × 10⁶ km² in 2000) to be 93±23 Pg C, taking into account lianas and small trees. Including dead biomass and belowground biomass would increase this value by approximately 10% and 21%, respectively, but the spatial variation of these additional terms still needs to be quantified.     

Experimental wood addition in streams: effects on organic matter storage and breakdown

1. Channel complexity affects the physical structure, biotic communities and functioning of stream ecosystems. Large wood (LW) is a key element in the creation and maintenance of physically complex stream channels in forested areas. 2. In an attempt to enhance stream habitat quality and ecosystem functioning and to reduce inputs of organic matter to a downstream reservoir, LW was experimentally introduced into four mountain streams in the Basque Country (northern Spain), ranging in channel width from 3 to 13 m. Following a before–after/control–impact (BACI) design, streams were monitored during 1 year prior to wood addition and during 2 years after addition in one control and one experimental reach per stream. 3. Areal cover of benthic organic matter in the entire channel was measured from regular transects and the mass of stored organic matter from random Surber samples. Breakdown of organic matter was assessed in litter bag experiments performed with black alder leaves. When 50% of the initial mass in the bags remained, invertebrates associated with leaf bags were collected. 4. Wood placement produced a 2‐ to 70‐fold increase in the storage of organic matter, especially in thick deposits upstream from wood jams, with values in excess of 2 kg AFDM per m² in the small streams. The accumulation of organic matter produced by wood introduction decreased with increasing stream size. 5. Despite the large increase in the availability of organic matter, litter breakdown rates were unaffected by the experimental reaches, suggesting large increases in the total amount of organic matter consumed at the reach scale. 6. Numbers of invertebrates and shredders per gram of leaf litter did not respond to wood addition. Average body mass of invertebrates associated with leaf litter showed a non‐significant decreasing trend, which might reflect increased recruitment. 7. Although the effects of wood addition can depend on wood stability and stream size, adding LW to restore channel complexity can improve environmental conditions for invertebrate communities and affect stream ecosystem functioning, enhancing the efficiency to use organic matter inputs on a reach scale.     

Chromosome counts in the genus Festuca L. section Festuca (Poaceae) in the Iberian Peninsula

Chromosome numbers have been counted in 102 populations belonging to 34 taxa of Festuca L. section Festuca from the Iberian Peninsula. Four of these taxa have been counted for the first time and another three for the first time from the Iberian Peninsula. Furthermore, the levels of ploidy for another three taxa have been obtained for new populations within their distribution area, and for another 18 taxa the ploidy levels have been confirmed. Five levels of ploidy have been established for this section: diploid, tetraploid, hexaploid, octoploid and decaploid. There are 17 diploid taxa, eight tetraploid, three octoploid, two octoploid and one decaploid. The three remaining taxa represent polyploid complexes (one tetra-hexa-octoploid and two hexa-octoploids).     

Comparative microsatellite typing of new world leishmania infantum reveals low heterogeneity among populations and its recent old world origin

Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe.     

Biogeographical analysis of two Polypodium species complexes (Polypodiaceae) in Mexico and Central America

We analyzed the geographical and elevational distributions of two Polypodium complexes from Mexico and Central America. Distribution data of nine species of the Polypodium colpodes complex and the Polypodium plesiosorum complex were obtained from almost 1500 herbarium specimens, field collections in Mexico and Costa Rica, and literature studies. The presence of each species was recorded for each Mesoamerican country, in 1° × 1° grid‐cells and biogeographical provinces. The rarity of species was also evaluated. Although the two complexes show extensive overlap, the P. colpodes complex is distributed mainly along the Pacific versant of Mexico and Central America, whereas the P. plesiosorum complex occurs mainly along the Atlantic versant. Those biogeographical provinces with maximum species diversity are Chiapas (seven species), Sierra Madre del Sur (six species), and the Trans‐Mexican Volcanic belt (six species). Grid‐cells with more species are located mainly in the mountains of central‐southern Mexico and northern Central America. Richness does not decrease or increase with latitude. Elevation distributions showed that most Polypodium species are concentrated in the montane interval and three species groups were recognized based on elevational preferences. Polypodium colpodes and P. plesiosorum are the most widely distributed species, whereas Polypodium castaneum and Polypodium flagellare are the only two species that possess the three attributes of rarity (narrow geographical distribution, high habitat specificity, and scarce local populations). Polypodium species of both complexes are present mainly in the montane regions of the study area and show some degree of geographical sympatry, especially in southern Mexico and northern Central America. This overlapping is explained by the elevation tolerance within montane systems and because most species inhabit three or more vegetation types. The distributional patterns of these complexes coincided with the three regional highlands of Mesoamerica, which are separated from each other by the Isthmus of Tehuantepec and by the lowlands of Nicaragua. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Natural Occurrence of Pepino mosaic virus in Lycopersicon Species in Central and Southern Peru

Pepino mosaic virus (PepMV), a potexvirus first described in 1980 from pepino ( Solanum muricatum ) plants cultivated in Peru, was isolated from diseased tomato plants in the Netherlands in 1999, and is now the cause of an emerging tomato disease in Europe. In a survey of central and southern Peru, 65 wild and four cultivated populations of Lycopersicon , as well as six populations of other species of Solanaceae , were tested for the presence of PepMV and six other viruses. Of the Lycopersicon population sampled, 23 (35.4%) reacted positively in double antibody sandwich (DAS)-enzyme-linked immunosorbent assay (ELISA) with antisera to PepMV. DAS-ELISA tests for PepMV of other solanaceous species were negative, except for one sample of pepino ( Solanum muricatum ). Mechanical inoculation of susceptible Lycopersicon esculentum cv. NE-1 plants with crude sap extracts of 20 of these samples confirmed that 15 of them (from the Departments of Apurimac, Arequipa and Moquegua) were infected with PepMV; these inoculated plants were also DAS-ELISA positive and, in most cases, developed symptoms. Thirteen of the infective extracts were obtained from plants of wild Lycopersicon species (three L. chilense , three L. chmielewskii , two L. parviflorum and five L. peruvianum ) and one each from the cultivated species L. esculentum and S. muricatum . The wild Lycopersicon species are newly reported natural hosts of PepMV. Tests for the other six viruses were negative, except that two samples contained Tomato mosaic virus . Thus, PepMV occurs in Lycopersicon species in central and southern Peru, even in isolated wild populations. These results indicate that the virus is not new to the region and has an efficient mechanism of natural transmission.     

Taphonomy and compositional fidelity of Quaternary fossil assemblages of terrestrial gastropods from carbonate-rich environments of the Canary Islands

Quaternary aeolian deposits of the Canary Islands contain well‐preserved terrestrial gastropods, providing a suitable setting for assessing the taphonomy and compositional fidelity of their fossil record over ~13 kyr. Nine beds (12, 513 shells) have been analysed in terms of multivariate taphonomic and palaeoecological variables, taxonomic composition, and the stratigraphic and palaeontological context. Shells are affected by carbonate coatings, colour loss and fragmentation. Shell preservation is size‐specific: juveniles are less fragmented and show colour preservation more commonly than adults. In palaeosols, the adult shell density correlates negatively with the proportion of fragmented adults, negatively with the proportion of juveniles, and positively with the proportion of adults with coatings. High bioturbation intensity in palaeosols is associated with low shell fragmentation and high proportion of shells with coatings. These relationships imply that high adult density in palaeosols was driven by an increase in shell production rate (related to a decrease in predation rates on adults and a decrease in juvenile mortality) and a decrease in shell destruction rate (related to an increase in durability enhanced by carbonate precipitation). In dunes, the relationships between taphonomic alteration, shell density and bioturbation are insignificant. However, dune assemblages are characterized by a lower frequency of shells with coatings and higher rates of colour loss, indicating lower shell durability in dunes than in palaeosols. Additionally, non‐random differences in the coating proportion among palaeosols imply substantial temporal variation in the rate of carbonate crust formation, reflecting long‐term changes in bioturbation intensity that covaries positively with shell preservation. Dunes and palaeosols do not differ in species abundances despite differences in the degree of shell alteration, suggesting that both weakly and strongly altered assemblages offer data with a high compositional fidelity. Carbonate‐rich terrestrial deposits originating in arid conditions can enhance the preservation of gastropods and result in fossil assemblages that are suitable for palaeoecological and palaeoenvironmental studies of terrestrial ecosystems.     

Typification of three taxa of the genus Festuca L. (Poaceae)

Lectotypifications of Festuca infesta Hack. ex Trab., Festuca maroccana Trab. and Festuca rubra L. subsp. scabrescens Hack. ex Trab. are designated here. The principal diagnostic characters and chorology are also presented for each taxon. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 342–343.     

The taxonomy of Galium crespianum J.J. Rodr. (Rubiaceae), a Balearic Islands endemic revisited

Galium crespianum J.J. Rodr. is a perennial plant inhabiting cliffs and crevices on the Balearic Islands. Although it was described from the mountains of Mallorca, several populations from the islands of Eivissa and Formentera have been traditionally considered as belonging to the same species. A careful comparison of specimens from the western and eastern Balearics revealed several discriminant features in gross morphology (robustness and habit of the stems, presence or absence of hairs at the internodes and leaves, waxiness of stems and leaves, shape of the inflorescence, flower colour and scent) and stem anatomy. In addition, several mutations in the ribosomal ITS sequences distinguished western and eastern plants. It is proposed that the plants from Eivissa and Formentera previously subsumed under G. crespianum be recognized at the specific level as G. friedrichii N. Torres, L. Saez, Mus & Rossello nom. nov. The new species is tetraploid (2n = 44) and shares morphological features with G. crespianum or with several taxa in the G. glaucum complex from the south east Iberian peninsula, to which it is most probably related.