Pampa Research Articles

Small-mammal consumption by sympatric canids in southern Brazil: niche overlap and prey selection

The crab-eating fox, Cerdocyon thous, and the pampas fox, Lycalopex gymnocercus, are two endemic canids from the neotropics that are sympatric in the Rio Grande do Sul State, southern Brazil. Previous studies indicated that both species feed mainly on small mammals, without marked differences between their diets, at least when small-mammal genera are not determined. In the present study, our objective was to evaluate the similarity in diet composition of those foxes, identifying the genera of small mammal consumed. Besides that, we also investigated potential patterns of prey selection by the canids. We analyzed 222 samples of fox feces from the National Park of Aparados da Serra (NPAS) in southern Brazil (29°10’S, 50°05’W) collected from 2000 to 2005. Fox species were determined by identification of hairs found in scats. We also conducted, between 2000 and 2002, a survey of small mammals using capture-mark-recapture techniques. Our results indicated that the species studied do not differ significantly in relation to the small mammals they consume. We also detected that both canids seem to prefer feeding on rodents of the genus Akodon. On the other hand, rodents of the genus Oligoryzomys were consumed less than would be expected. Our results indicated that prey similarity is very high for the studied canids, even under a more refined analysis of small-mammal preys. This pattern supports the suggestion that niche differentiation between C. thous and L. gymnocercus probably occurs through other mechanisms than diet (e.g. habitat or activity time). Key words: araucaria forest, cerdocyon thous, rodents, feeding habits, niche overlap, lycalopex gymnocercus.

ペルー，ナスカ台地とその周辺の耕地と水

ペルー，ナスカ台地とその周辺の耕地と水

Building large-scale spatially explicit models to predict the distribution of suitable habitat patches for the Greater rhea ( Rhea americana), a near-threatened species

We developed large-scale spatially explicit models to predict the distribution of suitable habitat patches for the Greater rhea ( Rhea americana), a near-threatened species, in two areas of central Argentina with different land use: a grassland area (ca. 4943 km 2) mainly devoted to cattle grazing and an agro-ecosystem area (ca. 4006 km 2) mostly used for crop production. The models were developed using logistic regression and were based on current records of Greater rhea occurrence coupled with remote sensing data, including land cover and human presence variables. The habitat suitability maps generated were used to predict the suitable habitat patch structure for wild rhea populations in each area. Fifty-one percent of the total grassland area was suitable for the species, being represented by a single large patch that included 62% of the individual locations. In the agro-ecosystem, only 28% of the total area was suitable, which was distributed among four patches. Seventy percent of rhea observations were in suitable habitat, with all rheas grouped in the largest patch. Conservation efforts for preserving wild rhea populations should be focused on maintaining habitats similar to grasslands, which are less profitable for landowners at present. Consequently, the protection of the pampas grasslands, a key habitat for this species as well as for others with similar habitat requirements, will demand strong conservation actions through the reconciliation of interests between producers and conservationists, since the proportion of croplands is increasing.

Procrustes analysis as a tool for land management

Fil: Matteucci, Silvia Diana. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Grupo de Ecologia del Paisaje y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Landscape associations of globally threatened grassland birds in the Aguapey river Important Bird Area, Corrientes, Argentina

SummaryThe Aguapey river basin in the Pampas grasslands of Argentina is the last refuge for a complete assemblage of globally threatened and Near Threatened birds. We evaluated the influence of landscape characteristics on the occurrence and abundance of six globally threatened and Near Threatened passerines. We used point counts to census birds and vegetation and quantified landscape characteristics 1,000 m from the count centres using remote sensing tools. Strange-tailed Tyrants Alectrurus risora were associated with higher percentages of tall-grass Andropogon lateralis in lowland areas. Saffron-cowled Blackbirds Xanthopsar flavus and Black-and-white Monjitas Heteroxolmis dominicana were associated with rolling landscape with wet lowland grasslands and marshes linked with dry upland grasslands. Marsh Seedeater Sporophila palustris and Chestnut Seedeater S. cinnamomea were associated with tall grasslands and marshes. Rufous-throated Seedeater S. ruficollis was not clearly associated with any type of habitat. The Aguapey grasslands are used mainly for livestock grazing and afforestation. Since 1995, approximately 50% of the original grassland habitat has been planted with exotic trees. If this trend continues, Saffron-cowled Blackbirds are likely to become extinct in the Aguapey river basin which currently supports the largest population of this species in Argentina. We recommend guidelines for establishing future reserves and wildlife management actions based on the landscape responses detected in this study. Future action should consider: maintaining connectivity between the Aguapey grasslands and the Ibera Nature Reserve, creating a protected area, designing a land use plan for the basin, avoiding afforestation in large blocks, removal of government incentives for large afforestation projects, and studying the viability of threatened bird populations in extensive cattle ranching areas.

Genetic structure of Greater Rhea (Rhea americana) populations in two regions with different land-uses in central Argentina

The distribution of populations of Greater Rhea (Rhea americana) are fragmented, probably owing to the conversion of grasslands to croplands. This study analyses the genetic structure of populations of Greater Rhea in areas with different degrees of anthropogenic alteration. Molecular variation was evaluated using Inter Simple Sequence Repeats (ISSR) markers in five wild populations that inhabit an agroecosystem and an area of semi-natural grassland. The populations were polymorphic for 23.33% of loci, with an average genetic diversity of 0.0822, and the populations of the two regions showed similar levels of variability. This low level of polymorphism may have be a result of historical bottlenecks and the long generation time of this species. The analysis of molecular variance showed highly significant differences among populations and non-significant differences between regions. The effects of habitat changes might not be the most important factor determining the genetic differentiation among populations currently. However, as modification of landscape structure of the Pampas grasslands could be more severe in the future, conservation of the Greater Rhea requires careful land-use planning.

Woody vegetation structure and composition of the last relicts of Espinal vegetation in subtropical Argentina

Until the beginning of the twentieth century there were extensive subtropical seasonal thorny forests surrounding the Pampas grasslands of Argentina, known as the ‘Espinal’. In central Argentina there still exist relicts of the Espinal, belonging to the ‘Entrerrianense District’. These forests were never described or analyzed in detail. In 2004 we studied 10 randomly located plots of 50 × 2 m. All individuals and stems of woody species were counted and their diameters at breast height (DBH) were measured; individuals with <1 cm DBH were considered juveniles. We recorded 2,300 woody individuals/ha corresponding to 12 species. The more constant species are the palm Trithrinax campestris (100%), Celtis tala (90%), Prosopis alba and Celtis pallida (both 50%). The plots are relatively homogeneous, but once classified with cluster analysis two groups are formed according to the relative abundance of C. tala and T. campestris; the latter species is more frequent in more open or fire-disturbed habitats. The results of Canonical Analysis of Principal coordinates are in agreement with the classification. We postulate that the differences between both groups are caused by a differential degree of disturbance (probably caused by fires). Both dominant species show abundant juveniles, and the invasion by exotic woody species is limited. These forest relicts are among the last remnants of the massive expansions of forests in central Argentina. Besides their historical value, an urgent call is made for their preservation, sustainable use and defence from biological invasions.

Late Summer Management Can Improve Forage Yield Distribution and Nutritive Value in Temperate Grassland

Chemical defoliation (glyphosate spraying) at the end of summer and fertilization are practices proposed to improve winter forage availability in native grasslands of the Flooding Pampa of Argentina. However, there is no preceding work comparing the effect of either practice on the yield and botanical composition of these grasslands. In 2002 and 2003, three defoliation treatments were applied in mid‐February: control (C) without summer defoliation; severe summer defoliation (D) to 2‐ to 3‐cm stubble height and glyphosate, isopropylamine salt of N‐[phosphonomethyl] glycine, G, applied at 2.2 kg a.i. ha−1. Additionally, the effect of three rates of N, 0, 35, and 70 kg N ha−1and P, 0, 11, and 22 kg P ha−1 applied in combination with the three late summer defoliation treatments were researched. Early changes during fall in the biomass components ryegrass (Lolium multiflorum Lam.), warm‐season grasses (WSG), dead matter, and litter were evaluated after defoliation treatments. The effect of defoliation treatments along with N and P fertilization was followed on seasonal and annual forage yield, botanical composition, in vitro dry matter digestibility (IVDMD), and crude protein (CP). Glyphosate application increased annual ryegrass contribution while reducing WSG and legumes, mostly narrow leaf trefoil (Lotus tenuis Waldst &amp; Kit.) and annually yielded 29% less forage dry matter (DM) than the intense mechanical defoliation. Forage IVDMD and CP were increased by D and G in fall the first year. In the second year CP was low in G in winter and spring. Changes in botanical composition can explain the differences observed in quality DM traits. Fertilizer increased forage yield 2 to 10 kg DM per kg N and 8 to 24 kg DM per kg P applied. Severe defoliation applied in late summer increased fall and winter forage availability and quality without the negative effect on legumes observed with glyphosate that had a negative impact on DM accumulation and quality in spring.

Flooding and grazing promote germination and seedling establishment in the perennial grass Paspalum dilatatum

AbstractSeed germination and seedling emergence are key processes for population recruitment. Flooding and grazing are disturbances forming gaps that may strongly influence recruitment patterns in space and time, but their combined effects and action mechanisms have rarely been addressed. In this study we analysed the effects of microhabitat conditions associated with winter flooding and spring‐summer defoliation on seed germination and seedling establishment of Paspalum dilatatum, a dominant perennial C4 grass in native grasslands of the Flooding Pampa, Argentina. The dynamics of seedling emergence from natural seed banks and buried seeds was studied in a factorial experiment with flooding and defoliation treatments applied to soil monoliths (mesocosms) collected from natural grassland. Additional laboratory experiments were applied to investigate seed germination under different combinations of temperature, light quality and simulated flooding. Seed germination and seedling emergence of P. dilatatum were promoted by flooding and high intensity defoliation. Gaps generated by flooding were maintained by high intensity defoliation exercising a synergistic effect on survival seedlings. Flooding resulted in the breaking of seed dormancy and higher germination rates associated with alternating temperature and the activation of the phytochrome system. Our results indicate that microhabitat conditions associated with the disturbances forming gaps, such as flooding and heavy grazing, synergistically promote the recruitment process of this dominant grass species.

Do seed and microsite limitation interact with seed size in determining invasion patterns in flooding Pampa grasslands?

Additive influences of the invasion ability of species (invasiveness) and the characteristics of the habitat which make it invasible (invasibility) cannot fully explain grassland invasion patterns. We tested the hypothesis that different species assemblages of grassland communities may partly result from interactive influences between the relative invasiveness of available species and community invasibility. During 10 months, we evaluated seed and microsite limitation of seedling emergence, survival, and recruitment of plants belonging to species with different seed size (large-seeded species vs. small-seeded species), with in a two-phase community mosaic typical of semi-natural grasslands in the southern flooding Pampa of Argentina. Seeds of large versus small-seeded species were sown either in species-poor patches dominated by a tall tussock grass (“pajonal”) or in species-rich patches dominated by short grasses (“matrix”), subjected to different levels of canopy disturbance (cut vs. uncut). Seed addition promoted seedling emergence for 7 out of the 10 species sown, and this effect was higher for large than for small-seeded species. After seed limitations were removed, interactive effects among seed size, community state and canopy disturbance reflected a strong positive influence of seed size on plant recruitment only in cut pajonal patches. Therefore, according to the stage of invasion process, relative species success may depend on non-interactive (seed-size effect on seed limitation to seedling emergence) or interactive influences among species invasibility and community invasiveness (from seedling emergence to plant recruitment). As a general conclusion, different assemblages of species are expected to successfully colonize spatially close grassland patches, according to both the available invasible species (seed size) and the community state and stage (species composition and canopy disturbance).

Mating Disruption for Control of &lt;I&gt;Melanotus okinawensis&lt;/I&gt; (Coleoptera: Elateridae) with Synthetic Sex Pheromone

A mating disruption experiment to control Melanotus okinawensis Ohira (Coleoptera: Elateridae) was conducted at a sugarcane (Saccharum spp.) field and a wild Japanese pampas, Miscanthus sinensis Anderss, grassland on Minami-Daito Island (3,057 ha) from 2001 to 2007. The sugarcane field and the pampas grassland were treated with synthetic sex pheromone that evaporated from a polyethylene tube dispenser. The mean total catches obtained by monitoring traps in the sugarcane fields decreased by 96.1% in 2001 from the previous year on Minami-Daito Island. The mean total trap catches in the treated area further decreased by 74.0% from 2001 until 2007 as cumulative effects. Simultaneously, the number of adults captured by hand decreased from 4.7 per sugarcane field in 2001 to 0.5 in 2007 (89.3% reduction), whereas those captured in the untreated area (Miyagi Island) did not show such a decrease. The mating rates were significantly lower in the females captured in the treated area (14.3-71.4%) than those in the untreated area (96.9-100%). However, the amount of the decrease in the trap catches was relatively small at first (39.6% reduction) in the Japanese pampas grassland on the periphery of the Island. This was probably due to the loss of pheromone substance caused by the strong seasonal wind in the periphery. However, mean total trap catches at the periphery also decreased within several years; significant decreases were detected until 2003, 2006, and 2007. These results indicated that the mating disruption effectively reduced an isolated population of M. okinawensis.

Mating Disruption for Control of Melanotus okinawensis (Coleoptera: Elateridae) with Synthetic Sex Pheromone

A mating disruption experiment to control Melanotus okinawensis Ohira (Coleoptera: Elateridae) was conducted at a sugarcane (Saccharum spp.) field and a wild Japanese pampas, Miscanthus sinensis Anderss, grassland on Minami-Daito Island (3,057 ha) from 2001 to 2007. The sugarcane field and the pampas grassland were treated with synthetic sex pheromone that evaporated from a polyethylene tube dispenser. The mean total catches obtained by monitoring traps in the sugarcane fields decreased by 96.1% in 2001 from the previous year on Minami-Daito Island. The mean total trap catches in the treated area further decreased by 74.0% from 2001 until 2007 as cumulative effects. Simultaneously, the number of adults captured by hand decreased from 4.7 per sugarcane field in 2001 to 0.5 in 2007 (89.3% reduction), whereas those captured in the untreated area (Miyagi Island) did not show such a decrease. The mating rates were significantly lower in the females captured in the treated area (14.3–71.4%) than those in the untreated area (96.9–100%). However, the amount of the decrease in the trap catches was relatively small at first (39.6% reduction) in the Japanese pampas grassland on the periphery of the Island. This was probably due to the loss of pheromone substance caused by the strong seasonal wind in the periphery. However, mean total trap catches at the periphery also decreased within several years; significant decreases were detected until 2003, 2006, and 2007. These results indicated that the mating disruption effectively reduced an isolated population of M. okinawensis.

Seasonal Diet of the Pampas Fox (Lycalopex gymnocercus) in the Chaco Dry Woodland, Northwestern Argentina

The seasonal diet of Pampas foxes (Lycalopex gymnocercus) was examined from 431 scat samples collected during 1 year in the dry Chaco woodland of Salta Province, northwestern Argentina. Fleshy fruits dominated the diet during the dry and wet seasons, representing 69% of the total frequency and comprising 91% of the total volume. Most of the fruit diet was contributed by 5 woody plant species. Mistol (Ziziphus mistol, Rhamnaceae), was the most important fruit resource throughout the year. Arthropods (particularly beetles and scorpions) and small mammals (mainly rodents and marmosets) were the most frequently consumed animal prey. Seasonal shifts in the frequency of the main food items in the diet were not significant, but there was considerable seasonal variation in the frequency of fruit species. Diversity of prey in the diet was highest in the wet season. The Pampas fox is a generalist feeder that can alter its diet to changes in food availability. However, its diet in the Chaco, which is dominated by fruit, differs from its diet in Pampas grassland habitat, where it consumes mostly meat.

Feral horses dung piles as potential invasion windows for alien plant species in natural grasslands

Small scale disturbances could act as patches that provide sites for the colonization of competitively inferior species, promoting the establishment of non-native species in some cases. We analyzed the vegetation associated with feral horse dung piles in montane pampas grasslands in Mid-East Argentina and described the changes following their abandonment, evaluating whether dung piles act as invasion windows, allowing the entrance of alien plant species. We estimated the portion of the study area directly covered by horse manure and dung height was used to estimate the time elapsed after the abandonment of each pile. Vegetation replacement on dung piles of different ages was assessed and compared with grassland controls using discriminant analysis. We used regression analysis to look for changes in vegetation cover, species richness, species diversity and evenness in response to height (age) of the dung piles, and principal component analyses (PCA) to identify groups of plants associated with different successional stages. We compared cover of alien plant species on dung piles with grassland controls using one-way ANOVA. On average, 2.5% of the study area was covered by horse dung. Total vegetation cover, species richness, diversity and evenness increased after the piles were abandoned. Characteristic plant groups were associated with initial, middle and last phases of the studied succession. Vegetation on the dung piles significantly differed from that in grassland controls and two species were consistently associated with dung piles: the invasive Red Star Thistle, Centaurea calcitrapa, and a native grazing-intolerant grass, Nassella clarazii. Non-native species cover was also higher in dung piles than in control plots. Dung piles cover a significant portion of grassland area in our study site, produce significant changes in the vegetation and are associated with some invasive alien plants that could eventually colonize more pristine areas in the vicinity. On the other hand, they might represent refuges for palatable species, since horses seem to avoid them for grazing.

Flooding tolerance of Paspalum dilatatum (Poaceae: Paniceae) from upland and lowland positions in a natural grassland

The grass Paspalum dilatatum Poir. subsp. dilatatum inhabits periodically flooded lowlands as well as non-flooded uplands of the flooding Pampa grasslands (Argentina), while P. dilatatum Poir. subsp. flavescens Roseng., B.R. Arrill. & Izag. inhabits only the upland sites. An experiment was designed to determine if there is local adaptation to flooding in physiological, anatomical and leaf morphological traits. To this end, plants of these populations were subjected to flooding (6 cm water depth) and control conditions (watered daily) for 60 days in an experimental garden. Flooded plants of the subsp. dilatatum from the lowland had 35% higher photosynthesis compared to controls without affecting their stomatal conductance, transpiration rate and leaf water potential. By contrast, both subsp. dilatatum and subsp. flavescens from the upland did not increase their photosynthesis, and had reduced their stomatal conductance and leaf transpiration rate by 35% and 45% when growing in flooded conditions. Upland populations had higher leaf water potential with respect to controls. All populations had high constitutive root aerenchyma (28–42%), and leaf sheath porosity increased by 75% in flooded conditions (from 22–28% to 35–48%). Leaf lengthening differed among populations according to their habitat: subsp. dilatatum from the lowland was the only one that had longer leaf sheaths and blade lengths when flooded. In contrast, flooded plants of subsp. dilatatum from the upland only increased leaf sheath length while subsp. flavescens neither increased leaf blade nor leaf sheath. In conclusion, both the physiological performance and the leaf length plasticity differed among populations. The results agree with those expected based on the species’ habitat, and indicate the better adaptation to the flood-prone habitat of P. dilatatum subsp. dilatatum taken from a lowland area.

Abundance and spatial distribution of Greater Rhea Rhea americana in two sites on the pampas grasslands with different land use

SummaryIn Argentina the original landscape structure of the pampas grasslands has changed rapidly due to intensified and specialized agricultural practices. The conversion of grasslands into croplands has been suggested as a threat to Greater Rhea Rhea americana populations. The main goals of this study were to estimate the abundance of Greater Rheas and to analyse the species' spatial distribution at two sites of the pampas region with different land use: agro-ecosystem and grassland. The former was mainly devoted to crop production whereas the latter was mostly used for livestock grazing. Data were collected through 14 aerial surveys from 1998 to 2001, and in 2004. Each survey consisted of six strip-transects per site, spaced at regular intervals. The total area surveyed represented 4% of each study site (113 km2 in the grassland and 95 km2 in the agro-ecosystem). Greater Rhea density (±SE) was significantly higher in the grassland (from 0.22 ±0.11 to 0.86 ± 0.24 ind. km−2) than in the agro-ecosystem (from 0.05 ± 0.05 to 0.12 ± 0.08 ind. km−2). Greater Rheas occupied 51% of the study area in the grassland but less than 5% in the agro-ecosystem. They showed a wide and uniform spatial distribution in the former area, whereas in the latter individuals occurred in small and isolated clusters. These results raise concern about the future of the species because, over recent years, land has been increasingly used for crop production. Hence, if the current rate of change in land use continues, the conservation status of this species will be seriously affected.ResumenEn Argentina, la estructura original de los pastizales pampeanos ha sufrido profundos cambios debido a la intensificación y especialización de las prácticas agrícolas. El reemplazo de pastizales por cultivos ha sido sugerido como una amenaza para las poblaciones silvestres de ãandú común Rhea americana. Los objetivos principales de este estudio fueron estimar la abundancia del ãandú común y analizar la distribución espacial de la especie en dos sitios de la región pampeana con diferente uso de la tierra: un agroecosistema y un pastizal. El primer sitio se caracteriza principalmente por la producción de cultivos mientras que la actividad predominante del segundo es la cría de ganado. Los datos fueron recolectados mediante 14 recuentos aéreos entre 1998 y 2001, y en 2004. Cada muestreo consistió en seis transectas de faja por sitio, colocadas a espacios regulares. El área muestreada representó el 4% del área total en cada sitio de estudio (113 km2 en el pastizal y 95 km2 en el agroecosistema). La densidad de los ãandúes (±ES) fue significativamente mayor en el pastizal (entre 0.22 ± 0.11 y 0.86 ± 0.24 ind. km−2) que en el agroecosistema (entre 0.05 ± 0.05 y 0.12 ± 0.08 ind. km−2). Los ãandúes ocuparon el 51% del área de estudio en el pastizal aunque menos del 5% en el agroecosistema. Los individuos presentaron una distribución espacial amplia y uniforme en el pastizal mientras que en el agroecosistema los ãandúes se encontraron en grupos pequeãos y aislados entre sí. Estos resultados resultan preocupantes para el fururo de la especie porque durante los últimos aãos, la tierra ha sido utilizada de manera creciente para la producción de cultivos. En consecuencia, si la tasa actual de cambio en el uso de la tierra continúa, el estado de conservación de esta ratite se verá seriamente afectado.

Modern vegetation–pollen–climate relationships for the Pampa grasslands of Argentina

AbstractAim To analyse the relationships between potential natural vegetation, pollen and climate in order to improve the interpretation of fossil pollen records and provide the background for future quantitative palaeoclimatic reconstructions.Location Pampa grasslands of Argentina, between 33–41° S and 56–67° W.Methods Modern pollen data were obtained from a pollen data base developed by the Grupo de Investigación de Paleoecología y Palinología, Universidad Nacional de Mar del Plata, Argentina (143 surface samples and 17 pollen types). Analysis of pollen and climate data involved multivariate statistics (cluster analysis and principal components analysis), scatter diagrams, Pearson’s correlation and isopoll mapping.Results Vegetation patterns at regional scales (grasslands and xerophytic woodlands) and local scales (edaphic communities) were identified by cluster analysis of pollen surface samples. The main climatic variables that appear to constrain the vegetation distribution and abundance of taxa are mean annual precipitation, annual effective precipitation and summer temperature. Individual pollen types such as Chenopodiaceae, Apiaceae, Cyperaceae, Prosopis, Schinus, Condalia microphylla and other xerophytic taxa are good indicators of moisture regime. Many pollen types are significantly correlated with summer temperature. The modern vegetation–pollen–climate relationships vary in a broadly predictable manner, supporting the contention that fossil pollen assemblages can be related to particular climatic characteristics.Main conclusions An expanded suite of modern analogues facilitated new insights into vegetation–pollen–climate relationships at the regional scale in Pampa grasslands. Relationships between individual pollen types and climate are appraised at a regional scale and new modern analogues are presented. The results provide the basis for improved vegetation and climate reconstruction from fossil records of the study area.

Linking vegetation heterogeneity and functional attributes of temperate grasslands through remote sensing

AbstractQuestion: How are plant communities of the Flooding Pampa grasslands spatially distributed? How do canopy dynamics of the different communities vary among seasons and years?Location: Buenos Aires province, Argentina.Methods: We characterized the distribution of communities through a supervised classification based on four Landsat 5TM images. We sampled species composition of 200 sites, with 130 of them corresponding to natural communities. Of the sampling areas 60% were used to classify, and the remaining areas to assess classification accuracy. We characterized the seasonal and interannual variability of canopy dynamics using NDVI (Normalized Difference Vegetation Index) data provided by MODIS /Terra images.Results: Overall accuracy of the classification was satisfactory. The resulting maps showed a landscape formed by a matrix of extended lowlands with small patches of mesophytic and humid mesophytic meadows. The October scene (near the peak of productivity) was particularly important in discriminating among communities. The seasonal pattern of NDVI differed among communities and years. Mesophytic meadows had the highest NDVI mean and the lowest interannual coefficient of variation, halophytic steppes had the lowest mean, and vegetated ponds were the most variable.Conclusions: These grasslands have a fine‐grained heterogeneity at the landscape scale. Each plant community has distinct seasonal and interannual canopy dynamics. These two features of grassland structure and functioning represent key information for rangeland management that may be obtained through a combination of minor field sampling and remote sensing.

Diversity and Distribution of Algae in Wetlands of the Rio Grande do Sul, Brazil

Surveys of algae diversity and distribution involving the Rio Grande do Sul State was completely unknown. The main goals of this study were to analyze the richness and distribution of the algae genera in wetlands of Rio Grande do Sul and to compare the algal composition among five geomorphologic provinces and between different wetland classes and types. A total of 146 wetlands were sampled within the five geomorphologic provinces of Rio Grande do Sul: Coastal Plain, Central Depression, Cristaline Shield, Highlands and Pampas. One single visit took place in each wetland from March to October 2002. A total of 107 genera of algae were found, distributed along five divisions: Cyanophyta, Heterokontophyta, Dinophyta, Euglenophyta, and Chlorophyta. The highest number of genera was found in Chlorophyta (52). Most of the observed genera presented a sporadic and occasional distribution in the wetlands of Rio Grande do Sul. The wetland algal composition of Cristaline Shield, Central Depression and Pampas was similar. While the planktonic algae were more associated with the aquatic bed vegetation (Gymnodinium, Scenedesmus and Ankistrodemus), and permanent wetlands (Dictyosphaerium and Ankistrodesmus), the periphytic algae were more associated with the emergent vegetation (Oscillatoria and Encyonema), and intermittent wetlands (Nostoc). The results showed a high richness and wide geographic distribution of the algae in wetlands of Rio Grande do Sul.

Lycalopex Gymnocercus (Carnivora: Canidae)

Lycalopex gymnocercus (Fischer, 1814) is a canid commonly called the Pampas fox. A sexually dimorphic fox-like carnivore of medium size with reddish coloration on sides and white on the ventral surface, it is 1 of 6 species in the genus Lycalopex. It occurs in eastern Bolivia, western and central Paraguay, Uruguay, north and central Argentina, and southeastern Brazil. It prefers open habitats but also occurs in areas of Pampas grassland modified by extensive ranching and agriculture activities. It has been assigned to the “Least Concern” category of the International Union for Conservation of Nature and Natural Resources.