Dry Vegetation Research Articles

Evaluation of the nutritional values of dry season Fadama vegetables in Bida, Nigeria

The proximate and mineral analysis of the some vegetables: Telfaria occidentalisHook. F., Ocimum gratissimum L., Hyptis suaveolens Poit., Talinum triangulare(Jacq.) Willd, Amaranthus hybridus L., and Corchorus olitorius L., were carried out to evaluate their nutritional value. Results showed high mean moisture contents ranging from 45.47 to 84.00%, low ash content ranging from 1.10 to 10.10%, and protein content ranging from 3.20 to 21.95%. Elemental analysis in mg/100 g indicated that the leaves and stem of the vegetable crops showed that they are rich sources of sodium, calcium, and potassium. There was complete absence of iron and magnesium in the vegetable crops. This result revealed that these vegetables are rich sources of nutrients and minerals essential for human growth and development. Key words: Elemental analysis, vegetables, nutritional value.

Long term land cover and seagrass mapping using Landsat and object-based image analysis from 1972 to 2010 in the coastal environment of South East Queensland, Australia

Long term global archives of high-moderate spatial resolution, multi-spectral satellite imagery are now readily accessible, but are not being fully utilised by management agencies due to the lack of appropriate methods to consistently produce accurate and timely management ready information. This work developed an object-based remote sensing approach to map land cover and seagrass distribution in an Australian coastal environment for a 38year Landsat image time-series archive (1972–2010). Landsat Multi-Spectral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery were used without in situ field data input (but still using field knowledge) to produce land and seagrass cover maps every year data were available, resulting in over 60 map products over the 38year archive. Land cover was mapped annually using vegetation, bare ground, urban and agricultural classes. Seagrass distribution was also mapped annually, and in some years monthly, via horizontal projected foliage cover classes, sand and deep water. Land cover products were validated using aerial photography and seagrass maps were validated with field survey data, producing several measures of accuracy. An average overall accuracy of 65% and 80% was reported for seagrass and land cover products respectively, which is consistent with other studies in the area. This study is the first to show moderate spatial resolution, long term annual changes in land cover and seagrass in an Australian environment, created without the use of in situ data; and only one of a few similar studies globally. The land cover products identify several long term trends; such as significant increases in South East Queensland’s urban density and extent, vegetation clearing in rural and rural-residential areas, and inter-annual variation in dry vegetation types in western South East Queensland. The seagrass cover products show that there has been a minimal overall change in seagrass extent, but that seagrass cover level distribution is extremely dynamic; evidenced by large scale migrations of higher seagrass cover levels and several sudden and significant changes in cover level. These mapping products will allow management agencies to build a baseline assessment of their resources, understand past changes and help inform implementation and planning of management policy to address potential future changes.

Percepción de apicultores sobre la importancia apícola de las plantas melíferas del bosque seco de la Línea Noroeste (República Dominicana)

Se estudiaron la flora melífera y su floración en la zona del bosque seco subtropical de la Línea Noroeste, de República Dominicana. Se aplicó una encuesta a 30 apicultores locales, así como 4 entrevistas semiestructuradas, sobre plantas de importancia para la actividad apícola. Se calificaron las plantas según su importancia; mediante observación, se confirmaron en campo las visitas de las abejas a las especies observadas y se consultó información secundaria sobre fechas de floración y características melíferas, información secundaria, y se aplicó el índice de Jaccard para determinar el grado de similitud entre el conjunto de las plantas mencionadas por los apicultores y las observadas en el campo. La coincidencia, relativamente buena, entre las plantas identificadas por los apicultores y las plantas en las que se observaron visitas de abejas en el campo confirma la validez del método. La mayoría de las plantas identificadas como melíferas son silvestres y pertenecen a la vegetación del bosque seco. Hay un período de floración abundante de marzo a junio y un período de escasez de septiembre a diciembre. Se recomienda la conservación de áreas significativas de bosque seco y de manglares en las áreas costeras, así como el establecimiento de cercas vivas y otros sistemas agroforestales<br />en el paisaje agrícola, que tengan en cuenta especies arbóreas<br />relevantes para la apicultura, con floración complementaria.

Asymmetric Variation in Soil Carbon Emission in Sub-Tropics

Carbon dioxide emission from soil, known as soil respiration, is one of the major sources of the atmospheric carbon. Understanding the relationship between emission rate and the factors associated with the emission process is important in global carbon emission management. The present study investigated soil respiration at three ecologically diverse locations in northern India. CO2 emission was measured in-situ by modified alkali absorption method at three different depths, top-soil (0 cm - 2 cm depth), mid-soil (20 cm depth) and deep-soil (40 cm depth) at each location. Rate of carbon emission from soil varied with location and time. The rate was higher at Riverine Zone (RZ) which had high soil moisture content and profuse ground vegetation compared to Hilly Zone (HZ) containing dry soil and scarce vegetation. The emission rate was also greater in grassland than the plantation area. Rate of carbon emission from soil was heterogeneous along different depths below the ground. Diel variation in emission rate was greater at HZ compared to RZ. Higher microbial population in soil was detected in RZ than HZ. However, the bacterial count out-numbered the fungal count in soils at most places. The study indicates a positive relationship between soil respiration rate and microbial abundance. The fungal population was strongly correlated with CO2 emission rate.

Techno-commercial aspects of food irradiation in India

Research and development work has been carried out at Food Technology Division of Bhabha Atomic Research Center for more than past fifty years. After establishing potential commercial applications, a lot of time and efforts were spent on proving the wholesomeness and nutritional adequacy of irradiated foods. The first approval from health authorities came in 1994 for processing potato, onion and spices. Additional commodities were approved in 1998 and 2001, bringing the list of commodities to more than 20. Two technology demonstration plants were set up by the government, one for high dose applications like microbial decontamination of spices and dry vegetables in 2000, and another for low dose applications, like sprout inhibition and insect disinfestation, in 2003. In 2004, irradiation was approved as a quarantine measure. This enabled export of mango to USA after a gap of 18 years in 2007. More than a dozen plants have now been set up by private entrepreneurs in the country.

The role of management on the rate of secondary succession in Mediterranean shrubland after fire

Ephemeral grasslands follow fire in Mediterranean batha communities on phosphorus-deficient terra-rossa soils, but successional processes rapidly restore shrub dominance. In an experiment aimed at reducing the rate of successional change and extending the period of grassland dominance, phosphorus was applied to a shrub community dominated by Sarcopoterium spinosum. This was done once in 1988, immediately after a fire. Two years later, the regenerating shrubs were treated with herbicide. Subsequently, the vegetation in the treatments was monitored for 20 consecutive years. The vegetation was undisturbed during the winter/spring growing season but was grazed during the dry summer of each year by beef cattle, which were given ad libitum access to poultry litter to supplement the nitrogen deficiency of the dry herbaceous vegetation. In control plots, the shrubs returned to pre-fire dominance within 5 years. With phosphorus and herbicide, shrub dominance was delayed by the vigorous herbaceous vegetation for more than 20 years. The practical feasibility of this management option depends on the relation between costs and benefits. A preliminary economic analysis based on the long-term experiment and a case study allowed us to define the conditions under which control of successional shrub encroachment can be economically feasible.

Response of dry grassland vegetation to fluctuations in weather conditions: a 9-year case study in Prague (Czech Republic)

AbstractThe extreme habitats of dry grasslands are suitable for investigations of the response of vegetation to local climate changes. The impact of weather variability on the dynamics of a plant community in a dry grassland was studied. Correlations were found between different functional groups of species and individual species and weather variability. During a 9-year study in five nature reserves in Prague (Czech Republic), the following responses of dry grassland vegetation to weather conditions were observed: (i) wetter conditions, especially in the winter, affected the dominance and species richness of perennial grass species and the decline of rosette plants; (ii) the year-to-year higher temperatures in the winter produced a decline in the dominance of short graminoids and creeping forbs; (iii) spring drought adversely impacted the overall abundance, especially the abundance of dicotyledonous species, and the species richness. However, these relationships may be manifested in different ways in different locations, and in some cases the vegetation of different locations may respond to weather conditions in opposite manners.

Seasonal energy and water balance of a Phragmites australis-dominated wetland in the Republican River basin of south-central Nebraska (USA)

Summary Climate and vegetation strongly influence the water cycle on local to regional scales. A change in the surface energy and water balance, especially in dry climatic regions, can have a significant impact on local water availability and, therefore, water resource management. The purpose of this study is to quantify the energy and water balance of a riparian wetland in a subhumid region of the central US, as well as the role of seasonal climate variability and vegetation phenology. The site is located in the Republican River basin in south-central Nebraska, where decreases in streamflow have been observed in recent decades. In an effort to reduce consumptive water use from evapotranspiration (ET), and thereby reclaim surface water, invasive species such as Phragmites australis have been removed throughout the riparian corridor of the river basin. In this study, we used energy/water balance monitoring stations, a Large Aperture Scintillometer (LAS), and numerous water and soil temperature probes to determine the energy and water balance during the 2009 growing season (April 11−October 3). Sensible heat flux was measured using the LAS, while ET was calculated as a residual of the energy balance (i.e., net radiation minus sensible heat flux and heat storage rates in the canopy, water, and soil). Rigorous quality control and uncertainty analyses were performed, and comparisons were also made with ET rates calculated via the simpler Priestley–Taylor method. Results of the energy budget analysis indicate that the average ET rate for the wetland during the growing season was 4.4 mm day −1 , with a maximum daily rate of 8.2 mm day −1 (occurring on June 29). Precipitation during the same 176-day period averaged 2.7 mm day −1 . Net radiation and vegetation phenology were found to be the two largest drivers of seasonal variability in ET. Sensible heat flux was significantly larger than latent heat flux early in the season, when standing vegetation in the wetland was still dry and brown. By late May and early June, however, Bowen ratios had declined well below 0.5 in response to greener and more abundant vegetation, higher transpiration rates, and reduced sensible heat flux. Heat storage rates in the wetland were dominated by changes in water temperature (as compared to soil or canopy heat storage) and comprised a significant portion of the hourly energy balance. On daily mean timescales, changes in the rate of heat storage corresponded to ∼13% of the variability in net radiation, while for the season-long average, the heat storage term was found to be essentially negligible. The Priestley–Taylor equation provided a reasonable estimate of ET during the height of the growing season but significantly overestimated ET during the beginning of the season (since it could not account for large sensible heat fluxes from the dry vegetation). Analysis of the wetland water balance showed seasonal variations in water level that were similar to changes in cumulative water inputs (i.e., precipitation minus ET). Portions of the season when the two curves had differing rates of change indicated periods of net water influx or outflux from other sources (primarily groundwater).

Pennsylvanian coniferopsid forests in sabkha facies reveal the nature of seasonal tropical biome

Research Article| April 01, 2011 Pennsylvanian coniferopsid forests in sabkha facies reveal the nature of seasonal tropical biome Howard J. Falcon-Lang; Howard J. Falcon-Lang * 1Department of Earth Sciences, Royal Holloway, University of London, Surrey TW20 0EX, UK *E-mail: h.falcon-lang@es.rhul.ac.uk. Search for other works by this author on: GSW Google Scholar Nathan A. Jud; Nathan A. Jud 2University of Maryland College Park, College Park, Maryland 20742, USA Search for other works by this author on: GSW Google Scholar W. John Nelson; W. John Nelson 3Illinois State Geological Survey, Champaign, Illinois 61820, USA Search for other works by this author on: GSW Google Scholar William A. DiMichele; William A. DiMichele 4Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Search for other works by this author on: GSW Google Scholar Dan S. Chaney; Dan S. Chaney 4Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Search for other works by this author on: GSW Google Scholar Spencer G. Lucas Spencer G. Lucas 5New Mexico Museum of Natural History and Science, 1801 Mountain Road, N.W., Albuquerque, New Mexico 87104, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Howard J. Falcon-Lang * 1Department of Earth Sciences, Royal Holloway, University of London, Surrey TW20 0EX, UK Nathan A. Jud 2University of Maryland College Park, College Park, Maryland 20742, USA W. John Nelson 3Illinois State Geological Survey, Champaign, Illinois 61820, USA William A. DiMichele 4Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Dan S. Chaney 4Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Spencer G. Lucas 5New Mexico Museum of Natural History and Science, 1801 Mountain Road, N.W., Albuquerque, New Mexico 87104, USA *E-mail: h.falcon-lang@es.rhul.ac.uk. Publisher: Geological Society of America Received: 17 Sep 2010 Revision Received: 15 Nov 2010 Accepted: 16 Nov 2010 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2011 Geological Society of America Geology (2011) 39 (4): 371–374. https://doi.org/10.1130/G31764.1 Article history Received: 17 Sep 2010 Revision Received: 15 Nov 2010 Accepted: 16 Nov 2010 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Howard J. Falcon-Lang, Nathan A. Jud, W. John Nelson, William A. DiMichele, Dan S. Chaney, Spencer G. Lucas; Pennsylvanian coniferopsid forests in sabkha facies reveal the nature of seasonal tropical biome. Geology 2011;; 39 (4): 371–374. doi: https://doi.org/10.1130/G31764.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Pennsylvanian fossil forests are known from hundreds of sites across tropical Pangea, but nearly all comprise remains of humid Coal Forests. Here we report a unique occurrence of seasonally dry vegetation, preserved in growth position along >5 km of strike, in the Pennsylvanian (early Kasimovian, Missourian) of New Mexico (United States). Analyses of stump anatomy, diameter, and spatial density, coupled with observations of vascular traces and associated megaflora, show that this was a deciduous, mixed-age, coniferopsid woodland (∼100 trees per hectare) with an open canopy. The coniferopsids colonized coastal sabkha facies and show tree rings, confirming growth under seasonally dry conditions. Such woodlands probably served as the source of coniferopsids that replaced Coal Forests farther east in central Pangea during drier climate phases. Thus, the newly discovered woodland helps unravel biome-scale vegetation dynamics and allows calibration of climate models. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Poissonia eriantha (Leguminosae) From Cuzco, Peru: An Overlooked Species Underscores a Pattern of Narrow Endemism Common to Seasonally Dry Neotropical Vegetation

The Peruvian Poissonia eriantha is segregated from peripatric Poissonia orbicularis and reinstated as the third unifoliolate species of Poissonia and the second from the Apurimac River basin in Peru. Poissonia eriantha is distinguished phenotypically and by DNA sequences from the ITS and cpDNA trnD-T region and morphology. This overlooked species is known from the type specimen and a recent collection from north of the Apurimac River in westcentral Cuzco where seasonally dry tropical forest vegetation predominates that is rich in succulent taxa (e.g. Cactaceae). Poissonia orbicularis is known from downstream along the Apurimac River and is disjunct further north along the Mantaro River, all within the same kind of seasonally dry vegetation. This seemingly small geographic distinction belies large genetic and phenotypic differences, a finding that may be most common to species groups confined to seasonally dry Neotropical forest vegetation. The case of Poissonia eriantha exemplifies the potentially high degree of niche conservatism and dispersal limitation that seasonally dry succulent-rich woodlands can impose on its constituent lineages.

Evolutionary biogeography of Manihot (Euphorbiaceae), a rapidly radiating Neotropical genus restricted to dry environments

Aim The aims of this study were to reconstruct the phylogeny of Manihot, a Neotropical genus restricted to seasonally dry areas, to yield insight into its biogeographic history, and to identify the closest wild relatives of a widely grown, yet poorly known, crop: cassava (Manihot esculenta). Location Dry and seasonally dry regions of Meso- and South America. Methods We collected 101 samples of Manihot, representing 52 species, mostly from herbaria, and two outgroups (Jatropha gossypiifolia and Cnidoscolus urens). More than half of the currently accepted Manihot species were included in our study; our sampling covered the whole native range of the genus, and most of its phenotypic and ecological variation. We reconstructed phylogenetic relationships among Manihot species using sequences for two nuclear genes and a non-coding chloroplast region. We then reconstructed the history of traits related to growth form, dispersal ecology and regeneration ability. Results Manihot species from Mesoamerica form a grade basal to South American species. The latter species show a strong biogeographic clustering: species from the cerrado form well defined clades, species from the caatinga of north-eastern Brazil form another, and so do species restricted to forest gaps along the rim of the Amazon basin. Vine and tree growth habits evolved repeatedly in the genus, as did fruit indehiscence and loss of ant-mediated seed dispersal. Main conclusions The genus Manihot probably originated in Mesoamerica, where it diversified prior to colonizing South America. Within South America, several groups then radiated southwards and eastwards within all kinds of seasonally dry lowland habitats. Some species also adapted to more humid environments, such as forest gaps, around the rim of the Amazon basin. Given the limited dispersal abilities of Manihot species, we propose that this radiation is most likely to have occurred only after, or shortly before, the completion of the Isthmus of Panama, around 3.5 Ma. Our results are in agreement with the past existence of a corridor of dry vegetation through Amazonia or along the eastern South American coast. In addition, our phylogeny allows identification of cassava’s closest wild relatives.

CONTENTS OF CADMIUM (Cd), CHROMIUM (Cr) AND LEAD (Pb) IN THE AGRICULTURAL LAND IN THE DRY MASS ALFALFA FROM VARIOUS LOCALITIES

This paper presents the results of the chemical analysis of the content of heavy metals (cadmium, chromium and lead) in the soils from the agricultural plots in four sites of the individual sector sown with the variety alfalfa Banat ZMS II. The test sites v. Jegunovce – Tetovo, v. Radusha – Skopje, and v. Kochilari – Veles are in the vicinity of certain pollutants (factory Jugochrom – Jegunovce, an abandoned mine for chromium and iron in Radusha, the smeltery of lead and zinc – Veles), while the v. Saraj – Skopje site is located in the middle of the noncontaminated environment and is taken for results comparation. The content of heavy metals (Cd, Cr and Pb) in the dry vegetation mass of the experimental alfalfa from the same sites was also researched in two phases of development where the following values were found such as 100 mg/kg soil).

WHAT HAPPENED TO THE COAL FORESTS DURING PENNSYLVANIAN GLACIAL PHASES?

Sequence stratigraphic analysis of Pennsylvanian coal-bearing strata suggests that glacial-interglacial fluctuations at high latitudes drove cyclic changes in tropical biomes. A literature review of plant assemblages in this paleoclimatic context suggests that coal forests dominated during humid interglacial phases, but were replaced by seasonally dry vegetation during glacial phases. After each glacial event, coal forests reassembled with largely the same species composition. This remarkable stasis implies that coal-forest refugia existed across the equatorial landscape during glacial phases, expanding to repopulate lowlands during and following deglaciation. One possibility is that refugia comprised small pockets of wetland forest strung out along valleys at some sites, but data are currently insufficient to test this hypothesis. The model presented here, if accepted, dramatically alters our understanding of the coal forests and helps explain aspects of their dynamics.

Numbers, foraging and refuelling of passerine migrants at a stopover site in the western Sahara: diverse strategies to cross a desert

Twice a year, songbirds breeding in the Western Palaearctic cross the largest desert of the world, the Sahara, to reach their African winter quarters. Recently, a radar study quantified this migration and demonstrated that almost all passerines cross the western Sahara with an intermittent strategy, i.e. they fly during the night and rest during the day. Before crossing the desert, most passerines accumulate fat stores because they will not find appropriate resting sites for feeding in the Sahara. However, it has also been reported that birds use the vegetation around oases for refuelling. Since birds resting at oases had smaller fat deposits than birds resting in the open desert, it was hypothesised that mainly lean birds or fall-outs use the oases for feeding. In this study, we investigated which species or individuals use oases in the western Sahara during spring migration and how they use them. We demonstrate that a minority of species adapted to dry vegetation may cross the Sahara with low energy stores and intermittent refuelling in vegetation patches. These birds avoid the costs of transporting large energy stores, in contrast to most other passerine migrants which fuel up before crossing the Sahara and adopt an intermittent strategy without refuelling. The birds which rely on refuelling at oases probably often have a slow refuelling rate and may even run the risk of not finding appropriate habitats. The available studies reveal that birds use a wide variety of strategies to cross the Sahara. The particular strategy adopted depends on the species, and is modulated according to weather conditions aloft at the time, existing energy stores, the availability of stopover sites, and the suitability (food availability, competitors) of stopover sites.

Separation and measurement of thorium, plutonium, americium, uranium and strontium in environmental matrices

A technique for the isolation of thorium (Th), plutonium (Pu), americium (Am), uranium (U) and strontium (Sr) isotopes from various environmental matrices has been adapted from a previously published method specific to water samples ( Maxwell, 2006). Separation and isolation of the various elemental fractions from a single sub-sample is possible, thereby eliminating the need for multiple analyses. The technique involves sample dissolution, concentration via calcium phosphate co-precipitation, rapid column extraction using TEVA™, TRU™ and Sr-Spec™ resin cartridges, alpha spectrometry for Th, Pu, U and Am and Cerenkov counting for Sr. Various standard reference materials were analysed and chemical yields are in the range of 70–80% for Th, Am, U and Sr and 50–60% for Pu. Sample sizes of up to 10 L for water, 5 g for dry soil and sediment and 10 g for dry vegetation and seaweed can be processed using this technique.

Systematics of Bolivian frogs of the genus Telmatobius (Anura, Ceratophryidae) based on mtDNA sequences

The aim of this work was to clarify the taxonomic status and phylogenetic relationships of the Bolivian frogs of the genus Telmatobius, which inhabit different kinds of habitats in the Andes. Sequences of the mitochondrial 16S and cytochrome b (cob) genes were analysed for representatives of most species and morphotypes of Telmatobius in the region; the morphologically diverse species of the T. marmoratus Complex were emphasized. Phylogenetic reconstructions (ML, MP, Bayesian) reveal three clades of Bolivian Telmatobius. A well-supported clade includes members of the T. verrucosus Group–T. sanborni, T. verrucosus and T. espadai, but relationships among them are not resolved. All the remaining taxa form a monophyletic group, the T. marmoratus–T. bolivianus Clade. Within this lineage, the well-defined T. marmoratus Clade includes all samples from the high-elevation Puna-Altiplano system (i.e. T. hintoni, T. huayra, T. marmoratus, T. culeus and T. gigas), whereas the poorly supported T. bolivianus Clade includes T. bolivianus, T. yuracare, T. sibiricus and T. simonsi. The only known population of T. gigas is deeply nested within T. marmoratus, indicating that there has not been enough time for mitochondrial lineages to achieve reciprocal monophyly. Telmatobius culeus, the Lake Titicaca frog, is sister to the T. marmoratus–T. gigas assemblage. Under different nucleotide substitution rate models for the cob gene, the analyses indicate that the divergence of the two clades from the common ancestor of all Bolivian Telmatobius occurred no more recently than 9 million years (My) ago (2%) and no earlier than 20 My ago (1%). During this time interval, the central Andes had not reached sufficient altitude to support Puna vegetation (assuming climatic conditions to have been similar to those today). A plausible rate of 2% implies that the appearance of highland species took place in the Pliocene, less than 5 My ago, which is consistent with the idea of an increased uplift rate for the Altiplano and eastern Cordillera of the central Andes since the late Miocene. This rapid uplift gave place to the Puna and highland dry vegetation types to which members of the T. hintoni and T. marmoratus groups are adapted. Under this model, the split of these two groups took place less than 2 My ago, and that of T. marmoratus (including T. gigas) and the ancestral lacustrine species T. culeus only c. 1.5 My ago.

Tree biomass estimation in regenerating areas of tropical dry vegetation in northeast Brazil

Allometric equations have been developed for various different vegetation types but have rarely been validated in the field and never for dry tropical forest such as caatinga. In three areas of semi-arid Brazil, with regenerating caatinga vegetation, we measured and weighed twelve hundred individuals of four tree species and used the data to validate equations previously determined in mature caatinga. They and several other equations developed for tropical vegetations overestimate the biomass ( B) of trees from the regeneration areas by more than 20%, possibly because these trees have reduced crowns, with lower branch masses. We then determined new allometric equations for them, validating equations for one site against data of the others and pooling the data if they were cross-validated. The best equations were power ones, based on diameter at breast height ( D), with little improvement by including height, crown area and/or wood density ( Caesalpinia pyramidalis, B = 0.3129D 1.8838; Croton sonderianus, B = 0.4171D 1.5601; Mimosa ophthalmocentra, B = 0.4369D 1.8493; and Mimosa tenuiflora, B = 0.3344D 1.9648 and 0.4138D 1.7718).

Cambios en la vegetación durante el Holoceno en la región Norte del Iberá, Corrientes, Argentina

Vegetation changes during the Holocene in the North Iberá, Corrientes, Argentina. Wetlands are very important sites for palynological studies, since they represent one of the most suitable environments for fossil pollen preservation. The aim of this work was to determine, by palynological analysis of lacustrine sediments, the vegetal communities and the predominant environment during the Holocene in NW of Iberá. Two lagoons were studied: San Sebastián and San Juan Poriahú. Sediment samples were obtained with witness using a "Levingstone square-rod sampler", processed with Faegri e Iversen techniques and dated with C14. The palynological graphs were divided in zones using the Tilia program. The palynological analysis allowed visualizing diverse changes in the vegetation: from 6 140 +/- 50 to 5 170 +/- 100 a. C., the NW of Iberá was characterized by marsh-herbaceous vegetation and arboreal vegetation typical of dry vegetation. From 5 170 +/- 100 to 3 460 +/- 60 a. C., a decrease in the species frequency, typical of wet environments, is produced, and the clogging of the waterbody, from 3460 +/- 60 a. C. onwards, while continuing the dominance of herbaceous vegetation typical of these environments, the arboreal pollen, indicates the beginning of a hygrophilous forest development.

Phylogeography of the cactophilic species Drosophila gouveai: demographic events and divergence timing in dry vegetation enclaves in eastern Brazil

AbstractAim The aim of this study was to assess the causal mechanisms underlying populational subdivision in Drosophila gouveai, a cactophilic species associated with xeric vegetation enclaves in eastern Brazil. A secondary aim was to investigate the genetic effects of Pleistocene climatic fluctuations on these environments.Location Dry vegetation enclaves within the limits of the Cerrado domain in eastern Brazil.Methods We determined the mitochondrial DNA haplotypes of 55 individuals (representing 12 populations) based on sequence data of a 483‐bp fragment from the cytochrome c oxidase subunit II (COII) gene. Phylogenetic and coalescent analyses were used to test for the occurrence of demographic events and to infer the time of divergence amongst genetically independent groups.Results Our analyses revealed the existence of two divergent subclades (G1 and G2) plus an introgressed clade restricted to the southernmost range of D. gouveai. Subclades G1 and G2 displayed genetic footprints of range expansion and segregated geographical distributions in south‐eastern and some central highland regions, east and west of the Paraná River valley. Molecular dating indicated that the main demographic and diversification events occurred in the late to middle Pleistocene.Main conclusions The phylogeographical and genetic patterns observed for D. gouveai in this study are consistent with changes in the distribution of dry vegetation in eastern Brazil. All of the estimates obtained by molecular dating indicate that range expansion and isolation pre‐dated the Last Glacial Maximum, occurring during the late to middle Pleistocene, and were probably triggered by climatic changes during the Pleistocene. The current patchy geographical distribution and population subdivision in D. gouveai is apparently closely linked to these past events.

Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands

Research Article| October 01, 2009 Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands Howard J. Falcon-Lang; Howard J. Falcon-Lang * 1Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK *E-mail: h.falcon-lang@es.rhul.ac.uk. Search for other works by this author on: GSW Google Scholar W. John Nelson; W. John Nelson 2Illinois State Geological Survey, Champaign, Illinois 61820, USA Search for other works by this author on: GSW Google Scholar Scott Elrick; Scott Elrick 2Illinois State Geological Survey, Champaign, Illinois 61820, USA Search for other works by this author on: GSW Google Scholar Cindy V. Looy; Cindy V. Looy 3Department of Integrative Biology, University of California–Berkeley, 3060 Valley Life Science Building, Berkeley, California 94720-3140, USA Search for other works by this author on: GSW Google Scholar Philip R. Ames; Philip R. Ames 4Peabody Energy, Evansville, Indiana 47715, USA Search for other works by this author on: GSW Google Scholar William A. DiMichele William A. DiMichele 5Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington D.C. 20560, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Howard J. Falcon-Lang * 1Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK W. John Nelson 2Illinois State Geological Survey, Champaign, Illinois 61820, USA Scott Elrick 2Illinois State Geological Survey, Champaign, Illinois 61820, USA Cindy V. Looy 3Department of Integrative Biology, University of California–Berkeley, 3060 Valley Life Science Building, Berkeley, California 94720-3140, USA Philip R. Ames 4Peabody Energy, Evansville, Indiana 47715, USA William A. DiMichele 5Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington D.C. 20560, USA *E-mail: h.falcon-lang@es.rhul.ac.uk. Publisher: Geological Society of America Received: 09 Feb 2009 Revision Received: 12 May 2009 Accepted: 26 May 2009 First Online: 03 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2009 Geological Society of America Geology (2009) 37 (10): 923–926. https://doi.org/10.1130/G30117A.1 Article history Received: 09 Feb 2009 Revision Received: 12 May 2009 Accepted: 26 May 2009 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Howard J. Falcon-Lang, W. John Nelson, Scott Elrick, Cindy V. Looy, Philip R. Ames, William A. DiMichele; Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands. Geology 2009;; 37 (10): 923–926. doi: https://doi.org/10.1130/G30117A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The idea that the Pennsylvanian tropical lowlands were temporally dominated by rainforest (i.e., the Coal Forest) is deeply ingrained in the literature. Here we challenge two centuries of research by suggesting that this concept is based on a taphonomic artifact, and that seasonally dry vegetation dominated instead. This controversial finding arises from the discovery of a new middle Pennsylvanian (Moscovian) fossil plant assemblage in southeast Illinois, United States. The assemblage, which contains xerophytic walchian conifers, occurs in channels incised into a calcic Vertisol below the Baker Coal. These plants grew on seasonally dry tropical lowlands inferred to have developed during a glacial phase. This xerophytic flora differs markedly from that of the typical clubmoss-dominated Coal Forest developed during deglaciation events. Although preserved only very rarely, we argue that such xerophytic floras were temporally as dominant, and perhaps more dominant, than the iconic Coal Forests, which are overrepresented in the fossil record due to taphonomic megabias. These findings require the iconography of Pennsylvanian tropical lowlands to be redrawn. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.