Distribution Of Grasses Research Articles

Study on the Method of Grass Yield Model in the Source Region of Three Rivers with Multivariate Data

This paper uses remote sensing and GIS technology to analyse the Source Region of Three Rivers (SRTR) to establish a grass yield estimation model during 2010 with remote sensing data, meteorological data, grassland type data and ground measured data. Analysis of the correlation between ground measured data, vegetation index based HJ-1A/B satellite data, meteorological data and grassland type data were used to establish the grass yield model. The grass yield model was studied by several statistical methods, such as multiple linear regression and Geographically Weighted Regression (GWR). The model's precision was validated. Finally, the best model to estimate the grass yield of Maduo County in SRTR was contrasted with the TM degraded grassland interpretation image of Maduo County from 2009. The result shows that: (1) Comparing with the multiple linear regression model, the GWR model gave a much better fitting result with the quality of fit increasing significantly from less than 0.3 to more than 0.8; (2) The most sensitive factors affecting the grass yield in SRTR were precipitation from May to August and drought index from May to August. From calculation of the five vegetation indices, MSAVI fitted the best; (3) The Maduo County grass yield estimated by the optimal model was consistent with the TM degraded grassland interpretation image, the spatial distribution of grass yield in Maduo County for 2010 showed a "high south and low north" pattern.

The potential distribution of yellow bristle grass (<i>Setaria pumila</i>) in New Zealand

Yellow bristle grass (Setaria pumila) an invasive annual grass weed in North America Africa Australia and New Zealand has become a problem on dairy farms in the upper North Island To define its potential distribution in New Zealand an ecoclimatic model was constructed using CLIMEX The model was parameterised using the known distribution of the species in its native range in Eurasia and validated against its invaded range in North America The model predicted all known occurrences in New Zealand and revealed extensive tracts of land in both the North and South Islands that are currently climatically suitable yet according to current records unoccupied by the weed Under climate change this potential distribution increases substantially These results imply that yellow bristle grass could become a much wider problem on dairy farms throughout New Zealand and that management to limit its spread is justified

Herbage intake, methane emissions and animal performance of steers grazing dwarf elephant grass with or without access to Arachis pintoi pastures

The inclusion of legumes in diets based on grass has nutritional benefits due to ingestive and digestive interactions (Niderkorn and Baumont 2009). Moreover, it is speculated that tropical legumes can contribute to reducing the emission of greenhouse gases (GHG) compared with diets exclusively composed of grasses (Archimede et al. 2011). However, under grazing conditions, these advantages are not always possible to obtain. This occurs when the spatial distribution of sward grasses limits access to legumes by grazing animals (Solomon et al. 2011). This can be the case, for example, when legumes are overlapped by the leaves of a tufted tall grass like dwarf elephant grass (Crestani et al. 2013). Considering that management strategies for increasing legume percentage in the diet of grazing animals should be investigated and data on enteric methane emitted by ruminants eating tropical forages are scarce, the aim of this work was to evaluate the effects on herbage intake, animal performance and enteric methane emissions of providing access to an exclusive area of forage peanut (Arachis pintoi cv. Amarillo) for cattle grazing dwarf elephant grass (Pennisetum purpureum cv. BRS Kurumi).

基于植被覆盖度的藏羚羊栖息地时空变化研究

The distribution and dynamics of vegetation can reflect the distribution and changes of wildlife habitat to some extent. Tibetan Antelope,well-known as‘the numen of plateau',is an endemic animal on the Qinghai-Tibetan Plateau.However,the survival and distribution of Tibetan Antelope have been threatened by environmental deterioration and illegal poaching. This animal has been listed as an Class I species by the Convention on International Trade in Endangered Species( CITES) and as Category I by the Key Protected Wildlife List of China. This situation has attracted a great deal of attentions from government and conservation professionals. The population distribution of Tibetan Antelope remains unkown in Altun National Nature Reserve. The Altun National Nature Reserve,the largest inland nature reserve of China established in May of 1983,is one of the four "no man' s-lands"in China. Due to its unique natural conditions,this reserve is preserving the rich natural resources,rare wild animals and plants.In this study,we analyzed the dynamics of vegetation in Altun National Nature Reserve based on remote sensing image data and GIS tool. The Normalized Difference Vegetation Index( NDVI) data were collected in 2000,2005 and 2010. We merged the regions,which were covered by vegetation in the study years and the suitable habitats were identified through interpreting vegetation types,which can be used by Tibetan Antelopes as grazing pastures. Based on NDVI datasetscollected in different years,we calculated the vegetation coverage and analyzed the spatial and temporal variations of vegetation coverage. Moreover,the changes of habitat were analyzed on the basis of vegetation coverage variations. The results showed that the vegetation coverage of the reserve was at a low level,and grids with low vegetation coverage took up about 50% of the regions that were covered by vegetation. The grids with high vegetation coverage were mainly distributed in the southwest of Kardun inspection station. The vegetation coverage in the regions where Tibetan Antelopes mainly lived was relatively higher,and that in the regions where the animal lambed was lower. The upward trends of vegetation coverage over time reflected the increase of the reserve's carrying capacity for animals,and it may also imply that the area of suitable habitat of this animal increased. The vegetation coverage of alpine steppe dominated by feather grass experienced a significant upward trend,also suggesting that carrying capacity of the reserve for Tibetan Antelope increased. The change of spatial distribution of feather grass steppe coverage indicated that habitat of Tibetan Antelopes might spread from east to southwest. The relationship between the altitude and vegetation coverage was not significant correlated. The study of habitat variations based on vegetation coverage is meaningful and can be used for better protecting this wildlife. Furthermore,we suggested that more factors could be integrated with vegetation coverage to precisely identify suitable habitat for animals,and more field surveys and monitoring should be conducted in the future.

Landscape Disturbances Impact Affect the Distribution and Abundance of Exotic Grasses in Northern Fescue Prairies

AbstractThe presence of landscape disturbances increases the establishment of exotic plants inside natural areas. Here, we examine the effect of human disturbances to prairie landscapes on the distribution and abundance of Kentucky bluegrass and smooth brome, exotic grasses that threaten the integrity of prairie ecosystems throughout the northern Great Plains. Using plant inventory data from Riding Mountain National Park in Manitoba, Canada, we investigated how roads, trails, and the intensity of historic livestock grazing affect the distribution and abundance of exotic grasses. On the basis of our results, both Kentucky bluegrass and smooth brome were more abundant in areas closer to roads. Kentucky bluegrass was also more abundant in areas farther from trails and those historically grazed by cattle. Our research demonstrates that the effect of landscape disturbances on exotic grasses varies between species and suggests that patterns of invasion may reflect different introduction histories. Given our findings, conserving the integrity of northern fescue prairies should account for human disturbances of landscapes and their effects on the proliferation of exotic plants into areas of native prairie.

Improved alpine grassland mapping in the Tibetan Plateau with MODIS time series: a phenology perspective

The Tibetan Plateau is primarily composed of alpine grasslands. Spatial distributions of alpine grasses, however, are not well documented in this remote, highly uninhabited region. Taking advantage of the frequently observed moderate resolution imaging spectroradiometer (MODIS) images (500-m, 8-day) in 2010, this study extracted the phenological metrics of alpine grasses from the normalized difference vegetation index time series. With the Support Vector Machine, a multistep classification approach was developed to delineate alpine meadows, steppes, and desert grasses. The lakes, permanent snow, and barren/desert lands were also classified with a MODIS scene acquired in the peak growing season. With ground data collected in the field and aerial experiments in 2011, the overall accuracy reached 93% when alpine desert grasses and barren lands were not examined. In comparison with the recently published national vegetation map, the alpine grassland map in this study revealed smoother transition between alpine meadows and steppes, less alpine meadows in the southwest, and more barren/deserts in the high-cold Kunlun Mountain in the northeast. These variations better reflected climate control (e.g. precipitation) of different climatic divisions on alpine grasslands. The improved alpine grassland map could provide important base information about this cold region under the pressure of rapidly changing climate.

Mechanisms driving an unusual latitudinal diversity gradient for grasses

AbstractAimFor most higher‐order taxa, species diversity peaks sharply in the moist tropics and declines rapidly at higher latitudes. However, the mechanisms driving this latitudinal gradient are numerous, remain uncertain and are even undocumented in some important major clades such as the grasses. Grasses are a cosmopolitan, important plant family with more than 11,000 species world‐wide. Our aims were: to investigate the latitudinal distributions of species richness for different grass lineages, and the grass family as a whole; and to test hypotheses proposed in general for the latitudinal diversity gradient or specifically as determinants of grass species richness patterns at the global scale.LocationGlobal.MethodsWe used the most comprehensive global database of grass distributions currently available to calculate species richness for 340 political regions of the world. Using generalized additive models we used these data to model the latitudinal gradients of species richness for different grass lineages and for the grass family as a whole. We constructed multiple regression models to include climatic, productivity, topographic, habitat and geographic variables.ResultsAn unusual, shallow latitudinal diversity gradient arises because different grass lineages exhibit contrasting latitudinal patterns. This reflects differential specialization of grass lineages to arid and cool environments, the legacy of historical effects, most notably the Gondwanan origin of the grasses, and a strong association between grasses and topographically heterogeneous, mountainous regions.Main conclusionsThe grasses are one of the relatively few higher‐order lineages that exhibits an atypical latitudinal gradient; this has arisen because of climatic specialization of particular grass lineages to cold and arid environments. Key additional roles have been inferred for historical biogeography and topographical heterogeneity in determining global patterns of grass species richness. These mechanisms have generally been under‐appreciated and are probably important for many other lineages.

Factors affecting the Luangwa (Zambia) hippo population dynamics within its carrying capacity band Insights for better management

This study assessed factors regulating the Luangwa (Zambia) hippo population within the carrying capacity band along the 165 km stretch of the Luangwa River, Eastern Zambia. Objectives of the study were to 1) establish whether the hippo population had reached and remained within the carrying capacity band in the last 32 years, and 2) determine the influence on population size and density distribution of grass biomass produced, mortality, non food resources (geomorphologic features) and levels of protection. Total river bank counts were made and global positioning system (GPS) locations of hippo schools recorded. Measurements from culled hippo carcasses were taken to determine sex and age classes. Kidney fat index (KFI) was used to determine body condition. Herbaceous growth was clipped and weighed to assess biomass. River geomorphologic features were taken by flying over the area in a light aircraft. Carrying capacity (K) was found to be 6,000 individuals at a density of 35 per km,oscillating within a carrying capacity band of 2,000 individuals in eight irregular cycles. At K,recruitment declined; calves and juveniles were 15% of the population and KFI was low at 40% by October. Grass biomass was high at 7, 850 kg/ha in 2008. Mortality did not disrupt population density. It was concluded that food was the main factor regulating hippo population size and density while geomorphologic features influenced the pattern of hippo population density distribution. Further research is required to establish primary production in ‘lean’ and ‘fat’ years and to monitor range trend condition as well as the impact of anthropogenic factors on the hippo population. Key words: Carrying capacity, primary production, body condition, geomorphologic features.

Upward expansion of fire‐adapted grasses along a warming tropical elevation gradient

High mountain regions in the tropics have thus far been impacted relatively little by anthropogenic activity or plant invasions, however, they are unlikely to be immune to impacts of global change, including climate change and other anthropogenic disturbances. Changes in fire regimes are known to accelerate the spread of invasive C4 grasses and interactions between changes in fire and climate can alter species distributions. The aim of this study was to compare grass distributions along an elevational gradient in Hawai‘i between 1966–1967 and 2008 to determine whether C4 and C3 grass distributions are shifting upward in response to alterations in fire and climate patterns. Field plots at Hawai‘i Volcanoes National Park were surveyed for grass species and cover at ˜150 m elevation intervals and compared to previous surveys done in 1966–1967. We found that the transition elevation, marking a shift in dominance between C4 and C3 grasses based on relative cover, shifted upward over 40 yr (95% confidence interval = 1476 m ± 130 m in 2008 versus 1200 m ± 106 m in 1966–1967). On the other hand, maximum elevations of all C4 or C3 grasses as a group were not significantly greater than 1966–1967 elevations; however, a subset of C4 (and fewer C3) grasses moved to substantially higher elevations, and these were the species adapted to fire. 100% of fire‐adapted grasses moved up in elevation compared to 29% of non‐fire adapted species, and the change in elevation of those species (=+454 m) was significantly greater than the change in elevation of non‐fire adapted species (p = 0.003). Our study documents an upward expansion of fire‐adapted grasses at high elevations in the tropics as an important threat that seems to be compounded by warming trends.

Ecosystem-scale spatial heterogeneity of stable isotopes of soil nitrogen in African savannas

Soil 15N is a natural tracer of nitrogen (N) cycling. Its spatial distribution is a good indicator of processes that are critical to N cycling and of their controlling factors integrated both in time and space. The spatial distribution of soil δ15N and its underlying drivers at sub-kilometer scales are rarely investigated. This study utilizes two sites (dry vs. wet) from a megatransect in southern Africa encompassing locations with similar soil substrate but different rainfall and vegetation, to explore the effects of soil moisture and vegetation distribution on ecosystem-scale patterns of soil δ15N. A 300-m long transect was set up at each site and surface soil samples were randomly collected for analyses of δ15N, %N and nitrate content. At each soil sampling location the presence of grasses, woody plants, Acacia species (potential N fixer) as well as soil moisture levels were recorded. A spatial pattern of soil δ15N existed at the dry site, but not at the wet site. Woody cover distribution determined the soil δ15N spatial pattern at ecosystem-scale; however, the two Acacia species did not contribute to the spatial pattern of soil δ15N. Grass cover was negatively correlated with soil δ15N at both sites owing to the lower foliar δ15N values of grasses. Soil moisture did not play a role in the spatial pattern of soil δ15N at either site. These results suggest that vegetation distribution, directly, and water availability, indirectly, affect the spatial patterns of soil δ15N through their effects on woody plant and grass distributions.

Determinants of perennial and annual grass distribution in Mediterranean-climate California

In California prairies, native perennial grasses have been almost entirely replaced by Eurasian winter-annual grasses. Landscape-scale descriptions of perennial versus annual grass distribution are lacking. To quantify perennial persistence in California grasslands, 50 randomly selected grassland meadows were sampled within three latitudinal belts of central California, from the Pacific coast inland to the Central Valley. Native perennial grasses were present at all but four of the sampling sites, although usually at low density. Proximity to the Pacific coast was positively correlated to perennial grass cover at all latitudes. Annual degree days above 18 °C and increasing slope were significantly negatively correlated to perennial grass dominance, and average warm season precipitation was significantly positively correlated to perennial dominance. Cover of non-native annual grasses was significantly lower in prairies <2 km from the coast than in all other sites. Non-native perennial grasses were occasionally important grassland community components at sites near the coast, but relatively uncommon inland. These results suggest that environmental conditions near the California coast tend to increase the success of perennial grasses, including exotic perennials. Intensity and duration of seasonal water stress likely play a central role in determining perennial grass distribution in California.

Monitoring the distribution of C3 and C4 grasses in a temperate grassland in northern China using moderate resolution imaging spectroradiometer normalized difference vegetation index trajectories

Using remote-sensing technologies, this study sought to provide an up-to-date map of C3/C4 distribution representative of temperate grassland in northern China. Several studies focused on the central grasslands of North America have demonstrated that C4 species coverage can be discriminated from C3 species by using time-series vegetation index data based on their phenological differences. Considering that the hydrothermal patterns and C4 percentage of grass flora in the study area and North America are different, we first examined temporal features of C3/C4 communities by using multitemporal moderate resolution imaging spectroradiometer nor- malized difference vegetation index data throughout the 2010 growing season. It was found that the asynchronous seasonality exhibited by communities with varied C3/C4 compositions also existed in our study region. Based on this asynchrony and separation rate, a hierarchical decision tree was developed to classify four grassland types with varied C3/C4 compositions. As a result, a classification map of the mixed C3/C4 grassland was generated with an overall accuracy of 87.3% and a kappa coefficient of 0.83. The geographic distribution of C3 and C4 species showed that the study area was dominated by C3 grasses, but C4-dominated grasslands accounted for 39% of the land cover. Thus C4 species also made an important contribution to grassland biomass, especially in dry and low-lying saline-alkaline habitats. The results also indicated that the trajectory-based methods for C3/C4 mapping rooted in asynchronous seasonality worked effectively in the climate regimes of both northern China and North America. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1.JRS.6.063535)

Predicting the current distribution and potential spread of the exotic grass Eragrostis plana Nees in South America and identifying a bioclimatic niche shift during invasion

AbstractEragrostis plana (Poaceae) is a perennial grass introduced from South Africa to the state of Rio Grande do Sul in southern Brazil. Currently, it is considered an invasive grass in several regions of the world, including South America, where it has caused negative ecological and socio‐economic impacts. Ecological niche models, using bioclimatic variables, are often used to predict the potential distribution of invasive species. In this study we prepared two bioclimatic models for E. plana using the Genetic Algorithm for Rule‐set Production, the first based on data from its native region (South Africa) and the second on data from both the native and invaded (South America) regions. We then projected each model onto South America to identify regions vulnerable to invasion by the species, and compared our results with available records of the species in South America. Finally, we explored the model's predictions for the existence of a bioclimatic niche shift during the invasion process of E. plana in South America, using multivariate statistical analysis. The model created with native distribution data was only able to predict (with highly suitable habitat) the region of introduction of E. plana in South America. However, the current distribution, as well as the region of introduction of the species, was reliably predicted by the model created with data from both native and invaded regions. Our multivariate analysis supports a hypothesis of bioclimatic niche shift during the invasion process of E. plana in South America.

Neotropical C3/C4 grass distributions – present, past and future

AbstractChanges in C4 grass distribution and abundance are frequently observed in Quaternary, Holocene and future environmental‐change scenarios. However, the factors driving these dynamics are not fully understood, and conflicting theories have been reported. In this paper, we present a very large dataset of modern altitudinal distribution profiles of C3 and C4 grasses covering the entire Neotropical Andes, which was compared with actual climate data. The results of multivariate analysis demonstrate that, in the Neotropical Andes, mean annual temperature is the main factor governing the modern altitudinal distribution of C3 and C4 grass species. The C3 and C4 grass distributions were compared with simulations based on the Lund‐Potsdam‐Jena dynamic global vegetation model (LPJ‐DGVM), which allowed the present grass distribution to be estimated. Finally, the DGVM was employed to simulate past and future scenarios, using the IPCC's climate projections for 2100 and PMIP2 models for the Holocene Optimum (HO, 6000 years bp) and the Last Glacial Maximum (LGM, 21 000 years bp). The results were found to be significantly different from those obtained using a simple photosynthetic model. According to LPJ forced with the PMIP2 models for the LGM, during the LGM, the C4 grasses would not have reached higher altitudes than found in the present day.

Geographical distribution and chorology of grasses in the Arabian Peninsula

Arid regions of Saudi Arabia occupy most of the area of the Arabian Peninsula. These areas are at the meeting position of plants from Mediterranean, Irano-Turanian, Saharo-Arabian, and Sudanian phytogegraphical regions. Geomorphology of the area reveals a wide diversity of landforms including coastal lines, desert plains, and high mountains. Grasses are well represented in the flora of Saudi Arabia and form an appropriate group for studying the relation of grass distribution, chorology, and photosynthetic pathways. In this paper, geographical distribution of C3 and C4 grasses was studied in an area extending between latitude 17°N and latitude 31°N. Two regions were recognized in the study area, namely; a (relatively) cold region north of latitude 24°N with ample winter rainfall, and a hot region south of latitude 24°N with scarce summer rainfall. Work involved field observations and collection of grass species in the study area. Work also depended on published carbon discrimination values of grasses and biochemical analysis of C4 species subtypes. Climatic conditions in the study area vary considerably, and the distribution of grass species was found to follow patterns that reveal adaptive advantages of different photosynthetic pathways. Grass species in the cold northern region with ample winter rainfall are generally C3 grasses belonging mainly to Mediterranean/Irano-Turanean chorotypes. C3 grass species found in the southern hot region were recorded at high altitudes of southern mountains characterized by low temperatures. Grass species recorded at low altitudes in the south hot region with scarce summer rainfall were mainly C4 grasses belonging to Tropical and Saharo-Arabian-Sudanean chorotypes. Pronounced spatial variations of temperature profoundly control the geographical distribution of C3 and C4 grasses. Low temperatures in the northern cold region and at high altitudes of the southern hot region limit the occurrence of C4 grasses and shift the ecological balance in favor of C3 grasses. Results are discussed in terms of heat sensitivity of the CO2 carboxylating enzyme of C3 grasses and high temperature optima for CO2 assimilation of C4 grasses. Results are also discussed in comparison with geographical distribution of grasses in other parts of the world.

Microbial Diversity in Zostera Sp. Beds in South-Western Black Sea Region Analyzed by Amplified Ribosomal DNA Restriction Enzyme Analysis (ARDRA)

ABSTRACTRecent declines in sea grass distribution in south-western Black sea coast arise the need of understanding microbial community relationships in sea grass beds that might affect the viability of these plants. Several factors and their impact on bacterial community were investigated, including the presence or absence of vegetation, depth into sediment, and a gradient of eutrophication formed from pollution point-source. Amplified Ribosomal DNA Restriction enzyme Analysis (ARDRA) showed similar community profiles, thus demonstrating no difference in dominant bacterial members in connection with vegetation. Although highly diverse, sediment community showed also stable annual tendency. This suggested no effect of anthropogenic impact on the main characteristics of bottom sediments in the Zostera endangered meadows.

Spatial patterns of grasses and shrubs in an arid grassland environment

In the Chihuahuan Desert of Mexico and New Mexico, shrub invasion is a common problem, and once-abundant grassland ecosystems are being replaced by shrub-dominated habitat. The spatial arrangement of grasses and shrubs in these arid grasslands can provide better insight into community dynamics and can provide information on grass shrub interactions. To better understand the dynamics of the Chihuahuan Desert ecosystem and to provide information regarding the interactions between grasses and shrubs, we examined the spatial patterns of grasses and shrubs in remaining grass-dominated areas, interspersed with some shrubs. We developed 18, 10 × 20 m vegetation distribution plots by mapping the location of all grasses and shrubs on each and repeating the measurements three years later. Spatial patterns were then assessed for each plot using a second-order spatial statistic, Ripley's K-function, as well as any observed changes in the spatial patterns over a three-year period. We observed clumped grass distributions, indicating a lack of competition among grasses; random shrub distributions; and even grass distribution with respect to shrub locations, indicating competition between grasses and shrubs. We also observed a tendency for grass distributions to become more even over time, and grasses to become less even with respect to shrub locations over time. These changes occurred during a period of greater than average rainfall, indicating that greater water availability may lead to increased competition among grasses and decreased competition between grasses and shrubs.

Native herbivores and plant facilitation mediate the performance and distribution of an invasive exotic grass

Summary1. Exotic plant species have become increasingly prominent features of ecological landscapes throughout the world, and their interactions with native and exotic taxa in these novel environments may play critical roles in mediating the dynamics of such invasions.2. Here, we summarize results from comparative and experimental studies that explore the effects of two factors – herbivory and facilitation – on the performance and distribution of an invasive South African grass,Ehrharta calycina, in a coastal foredune system in northern California, USA.3. Using a 2‐year exclosure experiment, we show that a native herbivore, black‐tailed jackrabbits (Lepus californicus), significantly reduced the height, shoot production, fecundity and above‐ground biomass of this exotic grass.4. Data from two comparative studies and a neighbour‐removal experiment revealed thatEhrhartafrequently escaped herbivores by associating with three neighbouring plant species – an exotic perennial grass,Ammophila arenaria, an exotic perennial succulent,Carpobrotus edulis, and a native perennial shrub,Baccharis pilularis.Ehrhartagrowing in association with neighbours was taller, had fewer grazed shoots, produced greater numbers of spikelets and had greater above‐ground biomass than unassociated individuals. Furthermore, removing neighbours generally eliminated these benefits in 7 months, although effects differed among neighbour species.5. An additional neighbour‐removal experiment conducted in the absence of jackrabbits indicated that neighbour removals did not have significant impacts onEhrhartaheight, shoot production, spikelet production or above‐ground dry biomass. These results suggest that the primary means by whichEhrhartabenefits from neighbouring plants is protection from herbivores – either because they are less apparent to herbivores or less accessible – and thatEhrhartalikely incurred minimal costs from associating with neighbours.6. Ehrhartawas more frequently associated with neighbours than expected due to chance, and less frequently found in open dune habitat. These results are consistent with the hypothesis that the effects of herbivory and facilitation have been sufficiently strong to shape the local distribution of this invader in the landscape.7. Synthesis. Our research has demonstrated that herbivory and facilitation have jointly influenced the dynamics of a biological invasion, and highlights the importance of evaluating the effects of multiple interactions on invasions in a single system.

Beckmannia Eruciformis (L.) Host in Slovakia - Distribution, Ecology and Coenotic Affinity: Dedicated to the memory of Ján Bogoly (1951 - 2011)

Beckmannia Eruciformis (L.) Host in Slovakia - Distribution, Ecology and Coenotic Affinity: Dedicated to the memory of Ján Bogoly (1951 - 2011)The historical and recent distribution, ecology and phytosociology of perennial grass Beckmannia eruciformis was studied in Slovakia between 2002 and 2010. Altogether 22 natural and two secondary sites with presence of the species were found from published sources, herbaria and field research. Localities of its native occurrence have been concentrated in Eastern Slovakia (Východoslovenská nížina Lowland from the settlement of Streda nad Bodrogom to the villages of Pribeník and Biel). Secondary sites were found in Western Slovakia (Podunajská nížina Lowland; the surroundings of Sládkovičovo town and Jaslovské Bohunice village). The relatively massive reduction of Beckmannia eruciformis localities was recorded in the seventies and eighties of the last century; it was related to massive land reclamation and alterations in the water regime of river alluvia. Recently only seven localities were found. Permanent occurrence was confirmed only in two localities (Malý Horeš, Strážne). In those cases Beckmannia eruciformis has created relatively large populations including some thousands of individuals. All other recent occurrences were temporary (Streda nad Bodrogom, Keresztúr farmstead, Horešské lúky Nature Reserve, Veľký Horeš, Pribeník). Moreover, they were relatively poor

The influences of climate, habitat and fire on the distribution of cockatoo grass (Alloteropsis semialata) (Poaceae) in the Wet Tropics of northern Australia

Cockatoo grass [Alloteropsis semialata (R.Br.) A. Hitchc.] is considered a keystone species in northern Australian ecosystems as it provides a food resource for many species, including several endangered vertebrates. This study examined both local and regional environmental factors influencing cockatoo grass distribution and abundance in the Wet Tropics of north Queensland, Australia. Local distribution and abundance were investigated in the sclerophyll ecotone between open woodland and tall open forest, because little is known about cockatoo grass distribution within this habitat; also, the endangered northern bettong (Bettongia tropica) is restricted to this habitat and depends on cockatoo grass for its survival. Regional-scale modelling of distribution was undertaken to examine the climatic tolerances of cockatoo grass in Queensland. Density of cockatoo grass was negatively related to litter cover, soil moisture, and the presence of two dominant grass species, Themeda triandra [Forssk.(R.Br.) Stapf] and Cleistochloa subjuncea (C.E.Hubb.). Soil nutrients (N, C, S, and C : N ratio) were positively related to density of cockatoo grass. A late dry season experimental burn demonstrated that cockatoo grass had high survival to fire, with increased density and flowering in response to fire. Regional-scale modelling using climate variables indicated that cockatoo grass is more suited to the drier end of the sclerophyll habitat range. Cockatoo grass in the woodland-forest ecotone in the Wet Tropics appears to be influenced by several environmental features associated with the ground layer. The species benefits from the reduction in litter cover and competing grass species that result from management actions such as prescribed burning. Understanding of the factors limiting this species, both at a local and regional scale, can be used to guide management of this ecotone habitat for both cockatoo grass and the survival of other species that depend on it.