Predominant Vegetation Research Articles

Soil carbon isotope ratios in forest-grassland toposequences to identify vegetation changes in southern Brazilian grasslands

The Southern Grasslands or Pampa biome covers 176,496km2 (2.07%) of the Brazilian territory, concentrated in the southernmost state with 63% covered by this biome. When adding Uruguay and Argentina, the biome area reaches 750,000km2. Rangelands are being substituted by crops and commercial eucalyptus, with potential impacts on ecological and hydrological response of watersheds and river basins. Studies of isotopic natural abundance may be used to understand vegetation dynamics in the past. We evaluated the natural abundance of 13C in soil profiles (ten soil layers down to 1.40m) at different positions of the landscape, in order to associate it with the vegetation dynamics in the studied environment. Two grassland areas and a forest area in the Pampa region of southern Brazil were sampled. Isotopic signature δ13C in the soil profile of the two grassland areas was dissimilar: one area is in the range of C4 plant formation, and the other followed the same trend up to the first 1.00m but from this depth on δ13C is in an intermediate range, which could have occurred due to the influence of C3 and C4 plants. Forest vegetation presents a clear change of predominant vegetation in a more-recent past period. Characteristic values of soil formed by C3 photosynthetic cycle plants are predominant in surface layers, whereas those of C4 plants predominate in deeper soil layers. Our hypothesis that soil classes, texture, and position in landscape are related to the presence/absence of riparian forest, as evaluated by the 13C isotopic abundance in soils from these sites, is accepted. Quantification of isotopic natural abundance allowed verifying changes in vegetation based on photosynthetic types predominant in the environments of grassland and native forests of the Pampa biome, and may provide information to manage this ecosystem.

Pollen distribution in surface sediments of the northern Lower Medjerda valley (northeastern Tunisia)

Past Mediterranean vegetation dynamics are commonly reconstructed using fossil pollen records. However, the interpretation of pollen records in terms of vegetation, climate and land-use changes is often limited due to complex pollen–vegetation relationships. So far, such relationships have been poorly examined in the semi-arid regions of Northern Africa. This work aims to document the modern pollen assemblages that reflect the main vegetation types associated to different land-uses in the northeastern Tunisia. For that, we collected 29 modern terrestrial surface samples in the Lower Medjerda valley and compared the pollen spectra to remotely sensed vegetation data. This original approach, coupling pollen and remotely sensed land cover data, presents some limitations and errors affecting both datasets although it gives promising results. Multivariate analyses show that the composition of pollen samples collected within the Mediterranean maquis may be strongly influenced by adjacent land covers such as conifer woodland or open vegetation. In contrast, pollen spectra associated with land-uses corresponding to heterogeneous agricultural areas and open landscape, mainly irrigated lands, have a distinct signature. However, close to water bodies, pollen spectra reflect predominantly the characteristic halophytic vegetation whatever the surrounding land cover types. We also examined the pollen composition of sediment core-tops from the lagoon Sidi Ali Mekki, to evaluate the ability of pollen sequences to record past vegetation and land-use histories in the Ghar el Melh region. We found that core pollen signal is mainly imprinted by the predominant local vegetation of Sidi Ali Mekki shore although regional and extra-regional pollen inputs appear stronger than in modern surface samples.

Scaling of soil carbon, nitrogen, phosphorus and C:N:P ratio patterns in peatlands of China

Inspired by the importance of Redfield-type C:N:P ratios in global soils, we looked for analogous patterns in peatlands and aimed at deciphering the potential affecting factors. By analyzing a suite of peatlands soil data (n = 1031), mean soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) contents were 50.51%, 1.45% and 0.13%, respectively, while average C:N, C:P and N:P ratios were 26.72, 1186.00 and 46.58, respectively. C:N ratios showed smaller variations across different vegetation coverage and had less spatial heterogeneity than C:P and N:P ratios. No consistent C:N:P ratio, though with a general value of 1245:47:1, was found for entire peatland soils in China. The Northeast China, Tibet, Zoige Plateau and parts of Xinjiang had high soil SOC, TN, TP, and C:P ratio. Qinghai, parts of the lower reaches of the Yangtze River, and the coast zones have low TP and N:P ratio. Significant differences for SOC, TN, TP, C:N, C:P and N:P ratios were observed across groups categorized by predominant vegetation. Moisture, temperature and precipitation all closely related to SOC, TN, TP and their pairwise ratios. The hydrothermal coefficient (RH), defined as annual average precipitation divided by temperature, positively and significantly related to C:N, C:P and N:P ratios, implying that ongoing climate change may prejudice peatlands as carbon sinks during the past 50 years in China.

ANÁLISE GEOAMBIENTAL DE UMA MICROBACIA HIDROGRÁFICA NO MUNICÍPIO DE LENÇÓIS, CHAPADA DIAMANTINA (BAHIA), BRASIL

This study aimed at surveying the physiography and land use in the small watershed of Lençóis River, in order to constitute an instrument for the management of natural resources. This small watershed is located in the municipality of Lençóis, Chapada Diamantina, state of Bahia, Brazilian Northeast. The waters drained by this small watershed are destined to the water supply of the city. The methodology used they based on geosystemic theories and methods and on the use of geoprocessing and remote sensing. The results indicated that the small watershed of Lençóis River is elongated, with a low branched and sparse hydrography. The climatic typology is tropical at altitude, and lithology is predominantly metasedimentary, with a structural geology defined by transcurrent fault, which controls the main fluvial channel. Sierras, valleys and river terraces, with an average slope of 27.5%, compose the geomorphology. The predominant vegetation cover class is the rupestrian fields. The levels of preservation of the vegetation cover, detected in the mapping, provide ensure of protection to the fluvial system, thus protecting the good natural condition of the predominant geoenvironmental units. At the geosystemic interface, the small watershed Lençóis River presents physical-environmental characteristics that suggest a management that values conservation, in order to ensure the balanced use of natural resources that promote socio-economic resources.

DIVERSIDADE DO BANCO DE SEMENTES EM DIFERENTES ÁREAS DE CAATINGA MANEJADAS NO SEMIÁRIDO DA PARAÍBA, BRASIL

A Caatinga, vegetação predominante da região semiárida do nordeste do Brasil, é formada por plantas com mecanismos eficientes que garantem a sua permanência no ecossistema. Seus estratos herbáceo, arbustivo e arbóreo fornecem alimento para os animais e diversos produtos para o homem e mantêm o banco de sementes como reserva para a recomposição florística. O objetivo deste trabalho foi comparar a densidade, a composição e a diversidade do banco de sementes de três áreas de Caatinga manejadas: área com plantio de craibeiras (A1), área degradada (A2) e área com plantio de juremas+sabiá (A3), localizadas na Fazenda Nupeárido, pertencente à Universidade Federal de Campina Grande (UFCG), Patos – PB, Brasil. Cinco amostras de serapilheira + solo de cada área foram coletadas e levadas ao Viveiro Florestal da UFCG e mantidas sob sombrite de 50% de redução solar e um regime de irrigação manual diária, onde permaneceram por 90 dias para contagem e identificação dos indivíduos emergentes. A densidade de plântulas foi comparada entre as três áreas através do teste do χ2 com P<0,05. A diversidade florística e a riqueza de espécies foram avaliadas utilizando os índices de Shannon-Wiener (H’) e de uniformidade de Pielou (e’), respectivamente. O banco de sementes foi composto predominantemente de espécies herbáceas nas três áreas e o estoque de sementes de espécies arbóreas teve incremento significativo na área de craibeiras resultante da presença prolongada de animais atraídos pelo conforto térmico local, proporcionado pelas copas.

Ecological survey of two Calomyscidae species; Goodwin's brush-tailed mouse and Hotson's brush-tailed mouse (Rodentia) in the eastern parts of Iran

Calomyscus elburzensis and C. hotsoni are two species of the rodents family Calomyscidae which are distributed mainly in Iran. Herein, we evaluated the habitat and ecological differences of these two brush-tailed mice in order to test the credibility of a hypothesis stating that species from habitats with different climates and vegetation show greater intraspecific differentiation than those from areas with more similar climates and vegetation. This study was carried out in four rocky regions in Iran between 2013 and 2015. Totally 52 brush-tailed mice were captured from Kopet-Dag, Khaje-Morad, Ark, and Shadan and Olang during the field studies. Maximum parsimony analysis inferred from mitochondrial DNA sequences (Cytb) was used for species identification, and also comparison of mean Kimura 2-paramater distances was performed. According to the molecular studies, specimens from the first two regions were assigned to C. elburzensis and samples from Ark, and Shadan and Olang belonged to C. hotsoni. The mean distances within all examined Iranian samples of both C. elburzensis and C. hotsoni were 2.3% and 0.9%, respectively. Based on our field studies, C. elburzensis were captured either from “cold mountainous” climate zone with Juniperus excelsa as main vegetation cover or from “Mediterranean” in which Pistacia atlantica is predominant vegetation. C. hotsoni were found in “hot dry desert” and “cold semi-desert” regions both characterized by Ephedra sp. and Avena sativa vegetation cover. Dog rose seeds were the main food of C. elburzensis in Kopet-Dag, whereas brush-tailed mice in the other three regions fed mainly on Mount Atlas pistache fruits. C. elburzensis inhabited concealed rock crevices, but C. hotsoni were found living in burrows which were digged in the soft soils. Individuals of C. hotsoni showed more calm behavior as compared with C. elburzensis. Meriones persicus and Cricetulus migratorius (Rodentia) as well as Ochotona rufescence (Lagomorpha) were the most abundant small mammals encountered with C. elburzensis, while M. persicus was the most successful rodent with sympatric colonies with C. hotsoni. In conclusion, in accordance with the greater genetic distances observed in C. elburzensis populations as compared with C. hotsoni, more significant differences in the habitat structure were also found for the first species in different parts of its distribution range.

Trophic pathways supporting Arctic grayling in a small stream on the Arctic Coastal Plain, Alaska

AbstractBeaded streams are prominent across the Arctic Coastal Plain (ACP) of Alaska, yet prey flow and food web dynamics supporting fish inhabiting these streams are poorly understood. Arctic grayling (Thymallus arcticus) are a widely distributed upper‐level consumer on the ACP and migrate into beaded streams to forage during the short 3‐month open‐water season. We investigated energy pathways and key prey resources that support grayling in a representative beaded stream, Crea Creek. We measured terrestrial invertebrates entering the stream from predominant riparian vegetation types, prey types supporting a range of fish size classes, and how riparian plants and fish size influenced foraging habits. We found that riparian plants influenced the quantity of terrestrial invertebrates entering Crea Creek; however, these differences were not reflected in fish diets. Prey type and size ingested varied with grayling size and season. Small grayling (<15 cm fork length (FL)) consumed mostly aquatic invertebrates early in the summer, and terrestrial invertebrates later in summer, while larger fish (>15 cm FL) foraged most heavily on ninespine stickleback (Pungitius pungitius) throughout the summer, indicating that grayling can be insectivorous and piscivorous, depending on size. These findings underscore the potential importance of small streams in Arctic ecosystems as key summer foraging habitats for fish. Understanding trophic pathways supporting stream fishes in these systems will help interpret whether and how petroleum development and climate change may affect energy flow and stream productivity, terrestrial–aquatic linkages and fishes in Arctic ecosystems.

Diversity and Impacts of Mining on the Non-Volant Small Mammal Communities of Two Vegetation Types in the Brazilian Amazon.

The Carajás National Forest contains some of the largest iron ore deposits in the world. The majority of the minerals are found below a plant community known as Savana Metalófila, or “Canga”, which represents only 3% of the landscape within the Carajás National Forest (CNF). The aim of our study was to understand the diversity of community of non-volant small mammals in the two predominant vegetation types: Ombrophilous Forest and Canga, and to examine how mining impacts these communities. Sampling was conducted from January 2010 to August 2011 in 11 sampling sites divided by the total area of Canga and 12 sampling sites in the forest, totalizing 23 sites. Of these, 12 sites (Canga and Forest) were considered impacted areas located close to the mine (<< 900 meters) and 11 sites (Canga and Forest), serving as controls, which were at least 7,000 meters from the mine. We recorded 28 species, 11 from the Order Didelphimorphia and 17 from the Order Rodentia. The two forest types shared 68.42% of the species found in the CNF. A gradient analysis (Non-metric multidimensional scaling) revealed that the first axis clearly separated the non-flying small mammal communities by vegetation type. Occupancy models showed that the detectability of species was affected by the distance from the mining activities. Of all the small mammals analyzed, 10 species were positively affected by the distance from mining in areas impacted (e.g. more likely to be detected farther from mining areas) and detectability was lower in impacted areas. However, three species were negatively affected by the distance from mining, with higher detectability in the impacted areas, and seven species showed no effect of their proximity to mining operations. To date, there are no studies in Brazil about the impact of mining on mammals or other vertebrates. This study reveals that the effect of mining may go beyond the forest destruction caused by the opening of the mining pits, but also may negatively affect sensitive wildlife species.

Where to Combat Shrub Encroachment in Alpine Timberline Ecosystems: Combining Remotely-Sensed Vegetation Information with Species Habitat Modelling.

In many cultural landscapes, the abandonment of traditional grazing leads to encroachment of pastures by woody plants, which reduces habitat heterogeneity and impacts biodiversity typical of semi-open habitats. We developed a framework of mutually interacting spatial models to locate areas where shrub encroachment in Alpine treeline ecosystems deteriorates vulnerable species’ habitat, using black grouse Tetrao tetrix (L.) in the Swiss Alps as a study model. Combining field observations and remote-sensing information we 1) identified and located the six predominant treeline vegetation types; 2) modelled current black grouse breeding habitat as a function thereof so as to derive optimal habitat profiles; 3) simulated from these profiles the theoretical spatial extension of breeding habitat when assuming optimal vegetation conditions throughout; and used the discrepancy between (2) and (3) to 4) locate major aggregations of homogeneous shrub vegetation in otherwise suitable breeding habitat as priority sites for habitat restoration. All six vegetation types (alpine pasture, coniferous forest, Alnus viridis (Chaix), Rhododendron-dominated, Juniperus-dominated and mixed heathland) were predicted with high accuracy (AUC >0.9). Breeding black grouse preferred a heterogeneous mosaic of vegetation types, with none exceeding 50% cover. While 15% of the timberline belt currently offered suitable breeding habitat, twice that fraction (29%) would potentially be suitable when assuming optimal shrub and ground vegetation conditions throughout the study area. Yet, only 10% of this difference was attributed to habitat deterioration by shrub-encroachment of dense heathland (all types 5.2%) and Alnus viridis (4.8%). The presented method provides both a general, large-scale assessment of areas covered by dense shrub vegetation as well as specific target values and priority areas for habitat restoration related to a selected target organism. This facilitates optimizing the spatial allocation of management resources in geographic regions where shrub encroachment represents a major biodiversity conservation issue.

Timely monitoring of Asian Migratory locust habitats in the Amudarya delta, Uzbekistan using time series of satellite remote sensing vegetation index

The Asian Migratory locust (Locusta migratoria migratoria L.) is a pest that continuously threatens crops in the Amudarya River delta near the Aral Sea in Uzbekistan, Central Asia. Its development coincides with the growing period of its main food plant, a tall reed grass (Phragmites australis), which represents the predominant vegetation in the delta and which cover vast areas of the former Aral Sea, which is desiccating since the 1960s. Current locust survey methods and control practices would tremendously benefit from accurate and timely spatially explicit information on the potential locust habitat distribution. To that aim, satellite observation from the MODIS Terra/Aqua satellites and in-situ observations were combined to monitor potential locust habitats according to their corresponding risk of infestations along the growing season. A Random Forest (RF) algorithm was applied for classifying time series of MODIS enhanced vegetation index (EVI) from 2003 to 2014 at an 8-day interval. Based on an independent ground truth data set, classification accuracies of reeds posing a medium or high risk of locust infestation exceeded 89% on average. For the 12-year period covered in this study, an average of 7504 km2 (28% of the observed area) was flagged as potential locust habitat and 5% represents a permanent high risk of locust infestation. Results are instrumental for predicting potential locust outbreaks and developing well-targeted management plans. The method offers positive perspectives for locust management and treatment of infested sites because it is able to deliver risk maps in near real time, with an accuracy of 80% in April-May which coincides with both locust hatching and the first control surveys. Such maps could help in rapid decision-making regarding control interventions against the initial locust congregations, and thus the efficiency of survey teams and the chemical treatments could be increased, thus potentially reducing environmental pollution while avoiding areas where treatments are most likely to cause environmental degradation.

Projections of climate change impacts on central America tropical rainforest

Tropical rainforest plays an important role in the global carbon cycle, accounting for a large part of global net primary productivity and contributing to CO2 sequestration. The objective of this work is to simulate potential changes in the rainforest biome in Central America subject to anthropogenic climate change under two emissions scenarios, RCP4.5 and RCP8.5. The use of a dynamic vegetation model and climate change scenarios is an approach to investigate, assess or anticipate how biomes respond to climate change. In this work, the Inland dynamic vegetation model was driven by the Eta regional climate model simulations. These simulations accept boundary conditions from HadGEM2-ES runs in the two emissions scenarios. The possible consequences of regional climate change on vegetation properties, such as biomass, net primary production and changes in forest extent and distribution, were investigated. The Inland model projections show reductions in tropical forest cover in both scenarios. The reduction of tropical forest cover is greater in RCP8.5. The Inland model projects biomass increases where tropical forest remains due to the CO2 fertilization effect. The future distribution of predominant vegetation shows that some areas of tropical rainforest in Central America are replaced by savannah and grassland in RCP4.5. Inland projections under both RCP4.5 and RCP8.5 show a net primary productivity reduction trend due to significant tropical forest reduction, temperature increase, precipitation reduction and dry spell increments, despite the biomass increases in some areas of Costa Rica and Panama. This study may provide guidance to adaptation studies of climate change impacts on the tropical rainforests in Central America.

Environmental Income of Livestock Grazing on Privately‐owned Silvopastoral Farms in Andalusia, Spain

AbstractIn Mediterranean silvopastoral ecosystems, grazing continues to be a key economic practice that shapes forest, woodland, shrubland and grassland and remains a primary feed source for livestock breeding. However, conventional national accounting statistics do not provide information on livestock grazing leases and environmental income. The main goals of this study were to apply the residual value method for measuring livestock grazing forage consumption and its private environmental price according to the predominant vegetation at the farm scale. We use data from a random survey of private landowners of indicated silvopastoral farms and a group of farm case studies with bookkeeping. Results indicate that livestock grazing average forage consumption per hectare in western and eastern Andalusia provinces are, respectively, 544 and 623 FU ha−1 for grasslands, 491 and 381 for Mediterranean hardwoods, 452 and 229 for shrublands and 268 and 548 for pine trees. The environmental price for livestock grazing forage unit in western and eastern provinces groups attains €0.05 FU−1 and €0.06 FU−1, respectively. This study is a novel contribution to the livestock grazing economics of private silvopastoral farms in Andalusia, Spain. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Quality of organic and upper mineral horizons of mature mountain beech stands with respect to herb layer species

The study analyses the chemical properties of the soil in open-canopy beech stands in relation to the predominant species of ground vegetation. A hypothesis is examined whether the predominant ground vegetation species can represent in chemical terms different site conditions. Four localities were used for testing reed grass, myrtle blueberry, wavy hair grass and vegetation-free patches. Samples were taken from three organic horizons (litter (OL), fragmented (OF) and humus (OH)) and from the humic first mineral horizon. Significant differences between the variants were found only in the OL horizon, in which the vegetation species explained 65% of the variability in data. The OL horizon in the vegetation-free variant showed the significantly lowest pH/KCl and the lowest potassium content. The most distinct particular differences were observed between the blueberry variant and the grass variants. Although the studied variants of vegetation growing under the beech stand represented significant differences in the litter horizon chemistry, the effects on the other humus horizons and on the upper mineral horizon were marginal.

Hyperspectral analysis in areas of Caatinga degraded in the municipality of Sertânia - PE

The brazilian region semiarid has as predominant vegetation the caatinga. The Caatinga Forest has one of its striking features its excellent adaptation to arid conditions. This exclusively brazilian ecosystem has a great biodiversity, but promote their preservation is a major obstacle to be overcome, one is the best knowledge of their chemical and physical processes. Thus the hyperspectral remote sensing can help enough in the characterization and monitoring of this ecosystem, where the hyperspectral data collected by these sensors can be transformed into different information biophysical aspects of vegetable toppings. In this work was used images hyperspectral of the Hyperion Satellite Earth Observing1 sensor (EO-1). The software utilized for analysis and the pre-processing of the image was the ENVI 4.4 software, where we generated the NDVI - vegetation index (Normalized Difference Vegetation Index) and the indexes of leaf pigments PRI (Photochemical Reflectance Index), SIPI (Structure Insensitive pigment Index) and CRI (1 Carotenoid Reflectance Index).The indices generated answered well to the structure of the cover and characteristics vegetation. Allowing this way, get more accurate data of vegetation indices and leaf pigments such, as chlorophyll and carotenoids.

A novel approach for the characterization of tundra wetland regions with C-band SAR satellite data

A circumpolar representative and consistent wetland map is required for a range of applications ranging from upscaling of carbon fluxes and pools to climate modelling and wildlife habitat assessment. Currently available data sets lack sufficient accuracy and/or thematic detail in many regions of the Arctic. Synthetic aperture radar (SAR) data from satellites have already been shown to be suitable for wetland mapping. Envisat Advanced SAR (ASAR) provides global medium-resolution data which are examined with particular focus on spatial wetness patterns in this study. It was found that winter minimum backscatter values as well as their differences to summer minimum values reflect vegetation physiognomy units of certain wetness regimes. Low winter backscatter values are mostly found in areas vegetated by plant communities typically for wet regions in the tundra biome, due to low roughness and low volume scattering caused by the predominant vegetation. Summer to winter difference backscatter values, which in contrast to the winter values depend almost solely on soil moisture content, show expected higher values for wet regions. While the approach using difference values would seem more reasonable in order to delineate wetness patterns considering its direct link to soil moisture, it was found that a classification of winter minimum backscatter values is more applicable in tundra regions due to its better separability into wetness classes. Previous approaches for wetland detection have investigated the impact of liquid water in the soil on backscatter conditions. In this study the absence of liquid water is utilized.Owing to a lack of comparable regional to circumpolar data with respect to thematic detail, a potential wetland map cannot directly be validated; however, one might claim the validity of such a product by comparison with vegetation maps, which hold some information on the wetness status of certain classes. It was shown that the Envisat ASAR-derived classes are related to wetland classes of conventional vegetation maps, indicating its applicability; 30% of the land area north of the treeline was identified as wetland while conventional maps recorded 1–7%.

Assessment of the Immediate Impacts of the 2013–2014 Drought on Ecosystems of the California Central Coast

Abstract. A methodology was developed to assess the impacts of the historic 2013–2014 drought on ecosystems of California's Central Coast region, using a combination of satellite image analysis and in situ measurements of soil moisture in predominant vegetation types of the region. According to differences in Landsat drought indices for plant water stress and vegetation green cover (NDWI and NDVI, respectively), the geographic areas within the study region that were most severely impacted by the 2013 drought were the inland Carmel Valley in northern Monterey County and the coastal zones around San Simeon Point and Cambria in northern San Luis Obispo County. An expanded area of severe vegetation moisture stress, generally indicated by relative-differenced NDWI values of >400, was detected by May 2014 in both of these same geographic areas. For more detailed examination of drought impacts, the entire study region was separated into the 3 predominant vegetation types (grasslands, shrublands, and forests) to ...

Soil and vegetation seasonal changes in the grazing Andean Mountain grasslands

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna (Vicugna vicugna) and alpaca (Lama pacos). The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined: total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. The good soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.

Site factors are more important than salvage logging for tree regeneration after wind disturbance in Central European forests

Wind disturbance is the main natural driver of forest dynamics in Central and Northern Europe, but little is known regarding the general patterns of tree regeneration following windthrow in this region. On the basis of 89 windthrow gaps, we quantified natural tree regeneration 10 and 20years after wind disturbance, and identified the factors influencing tree regeneration dynamics, with a special emphasis on the post-storm management practices “salvage logging” and “no intervention”. The sample encompasses gaps of ⩾3ha and total overstory mortality caused by wind disturbance. The gaps date back to the two catastrophic storm events Vivian in 1990 and Lothar in 1999. Gaps covered an ecologically diverse region extending over 20,000km2 and ranging from 370 to 1780ma.s.l. on the Central Plateau and in the Alps of Switzerland (Central Europe). Regeneration status was assessed on six circular sample plots per windthrow gap in 2010/2011. We recorded soil pH, organic layer, post-windthrow treatment, elevation, aspect, slope, browsing damage, and presence of predominant vegetation cover. We compared regeneration density and composition in gaps with and without salvage logging and elucidated the most important environmental factors influencing tree regeneration after wind disturbance using generalized linear models (GLMs). Ten and twenty years after wind disturbance, late-successional tree species such as beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) frequently dominated, independent of the post-storm treatment. Salvage logging did not negatively affect pre-storm regeneration and even positively influenced post-storm tree regeneration. GLMs revealed soil pH (+) and ground vegetation cover (−) to be the most important predictors of sapling density. The findings demonstrate that site factors have a stronger effect than post-storm treatment.

Gênese de solos coesos do leste maranhense: relação solo-paisagem

A ocorrência dos solos coesos no Brasil está relacionada dominantemente com os sedimentos argiloarenosos da Formação Barreiras, os quais estão geologicamente relacionados com os depósitos sedimentares do período Terciário, que constituem a unidade geomorfológica dos Tabuleiros Costeiros. Os objetivos deste trabalho foram identificar a ocorrência de solos coesos e estudar suas relações com a paisagem na região leste do Estado do Maranhão. A área do estudo localiza-se na Fazenda Typuana, região leste maranhense, no município de Brejo, MA, nas coordenadas geográficas de 03º 36' S e 42º 52' W. A vegetação predominante da área de estudo é do tipo Cerrado, com uma composição florística diversificada. Foram abertas três trincheiras, uma em cada área do estudo, com distintas formações vegetais para as caracterizações morfológica, física, química, mineralógica e a classificação taxonômica dos solos. A caulinita foi o mineral predominante nos horizontes coesos, porém seu grau de cristalinidade não influenciou na variação da densidade do solo (1,40 a 1,56 kg dm-3) e na resistência à penetração (1,24 a 2,18 MPa). Constatou-se que a posição da paisagem foi determinante para a distinção dos solos coesos, de modo que os desenvolvidos em pedoforma côncava apresentaram a maior expressão do caráter coeso e com maior status de fertilidade e matéria orgânica, refletindo na vegetação mais exuberante, caracterizada pelo Cerradão.

Exploring the Feasibility of Sclerotium rolfsii VrNY as a Potential Bioherbicide for Control of Swallowworts (Vincetoxicum spp.)

AbstractPale swallowwort (PSW) and black swallowwort (BSW) are two viney milkweeds native to Europe that have increasingly become problematic and noxious weeds in eastern North America. An indigenous fungal isolate, Sclerotium rolfsii VrNY, was discovered causing significant mortality in a dense stand of PSW in a park in upstate New York. Although this fungus is a known pathogen with a broad host range, we evaluated the host potential of S. rolfsii VrNY on a limited range of related and nonrelated U.S. species as a critical first step to assess its suitability as a mycoherbicide for PSW and BSW. In addition, PSW and BSW produce the specific stereoisomer (−)-antofine, a compound with antimicrobial and phytotoxic activity that could inhibit the pathogen. Tests revealed this compound had no effect on S. rolfsii VrNY. This isolate caused significant mortality on all broadleaf plants tested (Asclepias syriaca, Asclepias curassavica, Apocynum cannabinum, Monarda fistulosa, Rudbeckia hirta, PSW, BSW) with the exception of Glycine max, and had no effect on the monocots Schizachyrium scoparium and Zea mays. Although these laboratory studies indicate that most broadleaf vegetation may be susceptible to the pathogen, S. rolfsii might have potential as a mycoherbicide in natural eco-niche environments where invasive PSW and BSW have already become the predominant vegetation. Further laboratory testing of S. rolfsii and limited field testing at the initial discovery site are needed in order to prevent premature rejection of this isolate as a potential management tool against these highly invasive weeds.