Explore the vast range of titles available.

Saccharum spontaneum L. is a perennial tall grass and invades naturally abandoned and pastoral lands in many tropical countries. Although it is a potentially multiple-use and multifunctional species, it remains neglected and underutilized. It is commonly known as ‘Wild cane’ in English and ‘Kans’ in Hindi. In recent years, S. spontaneum has attracted serious attention for its potential in ecological restoration. The present paper deals with geographic distribution, ecology, morphological description, multiple uses, restoration potential, and propagation of this species. We also report the suitability of S. spontaneum for the restoration and stabilization of bare fly ash (FA) dumps. In this context, the highest importance value index, visual observations and practitioner insights reveal that S. spontaneum has great ability to grow on bare FA dumps and can be used as an ecological tool in restoration of vast tracts of fly ash dumps across the world. Besides grass vegetation study, we also report the change in physicochemical properties of abandoned site and compared with naturally colonized site with S. spontaneum of FA dumps to assess its ecological suitability for restoration of bare FA dump. Overall, the field results showed that S. spontaneum is a promising and potential tall grass for the restoration of FA dumps.

Background and aims Perennial tall-grasses have experienced a successful expansion in the last decades leading in some cases to extremely degraded communities, which remain in an alternate stable state. This research focuses on the mechanisms of persistence of the spreading native Brachypodium pinnatum in acidic soils. We hypothesize that plant-herbivory feedbacks and an adapted response to soil constraints, promote species cover stability. Methods Eight on-site populations of the species growing in two contrasted situations (high-diversity grazed and low-diversity ungrazed communities) were sampled during a growing season and analysed for nutrient (N, P and K), metal (Al) and C allocation, biomass production and tissue quality. Results The species showed a high capacity for belowground accumulation of Al and an efficient reallocation and resorption of nutrients, which may explain its success in acidic, poor soils. The lack of attractiveness to herbivores of the species-poor stands prevented biomass removal, which strengthened some effects and enhanced the build-up of a thick layer of recalcitrant tissues, an effective barrier (aboveground and belowground) for the establishment of sympatric species. Conclusions Density-dependent feedback mechanisms (herbivory attractiveness), and the particular attributes of B. pinnatum (i.e. powerful rhizomes with a selective performance for nutrients and aluminium) may lead to critical processes of community domination and degradation.

. In the mesic grasslands of the central United States, the shrub Cornus drummondii has undergone widespread expansion in the absence of recurrent fire. We quantified alterations in light, water and N caused by C. drummondii expansion in tall‐grass prairie and assessed the hypothesis that these alterations are consistent with models of resource enrichment by woody plants. Responses in graminoid species, particularly the dominant C4 grass Andropogon gerardii, were concurrently evaluated. We also removed established shrub islands to quantify their legacy effect on resource availability and assess the capability of this grassland to recover in sites formerly dominated by woody plants. The primary effect of shrub expansion on resource availability was an 87% reduction in light available to the herbaceous understorey. This reduced C uptake and N use efficiency in A. gerardii and lowered graminoid cover and ANPP at the grass‐shrub ecotone relative to undisturbed grassland. Shrub removal created a pulse in light and N availability, eliciting high C gain in A. gerardii in the first year after removal. By year two, light and N availability within shrub removal areas returned to levels typical of grassland, as had graminoid cover and ANPP were similar to those in open grassland. Recovery within central areas of shrub removal sites lagged behind that at the former grass‐shrub ecotone. These results indicate that the apparent alternative stable state of C. drummondii dominance in tall‐grass prairie is biotically maintained and driven by reductions in light, rather than resource enrichment. Within areas of shrub removal, the legacy effect of C. drummondii dominance is manifest primarily through the loss of rhizomes of the dominant grasses, rather than any long‐term changes in resource availability. C. drummondii removal facilitates grassland recovery, but the effort required to initiate this transition is a significant cost of woody plant expansion in mesic grasslands. Prevention of woody plant expansion in remnant tall‐grass prairies is, therefore, a preferred management option.

Urban rights-of-way may be potential reservoirs of tall-grass prairie plants and butterflies. To determine if this is true, in 2007–2008, we conducted vegetation surveys of species richness and cover, and butterfly surveys of species richness and abundance, along 52 transmission lines and four remnant prairies in Winnipeg, Manitoba. We detected many prairie plants and butterflies within transmission lines. Some unmowed and infrequently managed transmission lines had native plant species richness and total percent cover of native plants comparable to that of similar-sized remnant tall-grass prairies in the region. Although we did not find significant differences in overall native butterfly numbers or species richness between rights-of-way and remnant prairies, we found lower numbers of some prairie butterflies along frequently mowed rights-of-way than within remnant tall-grass prairies. We also observed higher butterfly species richness along sites with more native plant species. By reducing mowing and spraying and reintroducing tall-grass prairie plants, urban rights-of-way could serve as extensive reservoirs for tall-grass prairie plants and butterflies in urban landscapes. Eventually, managing urban rights-of-way as reservoirs for tall-grass prairie plants and animals could contribute to the restoration of tall-grass prairie in the North American Midwest.

Vegetation analysis reveals that the Themeda quadrivalvis tall-grass savannah in Oman, southern Arabia, forms a clearly defined belt with strong edaphic and geomorphological characteristics. The newly described association Desmodio gangetico-Themedetum quadrivalvis ass. nov. is interpreted as an impoverished easternmost outlier of the East African savannah.

Regional differences in Caragana microphylla density in the Mongolian steppes were explained by considering multiple abiotic and biotic factors collectively, including aridity gradients, grazing regimes, fire disturbance, and interspecific interactions. In the central and eastern Mongolian steppes, we collected vegetation data from 127 sites. Along 250-m line transects, the hit frequencies of C. microphylla and tall-grass species were recorded. Ancillary data included weather information, livestock populations, fire occurrence maps, and herder camp locations. Based on the steppe types and disturbance regimes, the sites were classified into 12 sub-groups. The data were statistically analyzed at the site, county, and sub-group levels. The natural C. microphylla density decreased with climatic aridity from forb-steppes to semi-desert steppes, but this pattern was not observed at grazed and burned sites. Livestock grazing decreased C. microphylla density, but this effect was considerably confounded by aridity effects, especially in the central steppes, making the relationship between C. microphylla and livestock densities complex. Although fire appeared to be an important factor in the eastern steppes, the mechanism of its effect on C. microphylla density was unclear, because the fire–shrub interaction is influenced by the tall-grass recovery process after fire. Based on our results, we propose that two different confounding effects, namely aridity versus grazing and fire versus interspecific interactions, play important roles in determining the spatial distribution of C. microphylla density in the central and eastern Mongolian steppes, respectively.

Nonlethal (trait-mediated) effects of predators on prey populations, particularly with regard to prey dispersal, scarcely have been considered in spatial ecological studies. In this study, we report on the effects of spider predators on the mortality, dispersal, and spatial population dynamics of Prokelisia crocea planthoppers (Hemiptera: Delphacidae) in a prairie landscape. Based on a three-generation survey of host-plant patches (Spartina pectinata; Poaceae), the density of cursorial and web-building spiders declined significantly with increasing patch size (a pattern the opposite of that for the planthopper). Independent of patch size effects, an increase in the density of web-building and cursorial spiders had a negative effect on planthopper density in one of three generations each. Finally, the likelihood of extinction of local (patch) populations of planthoppers increased significantly with an increase in the density of web-building spiders. Planthoppers in small host-plant patches with high densities of web-building spiders were especially at risk of extinction. To evaluate whether spider effects on planthopper spatial dynamics were mediated by predation and/or spider-induced dispersal, we performed a field experiment in which host-plant patches were either caged or left open and received one of three spider density treatments (removal, ambient levels, or high = triple ambient levels). For the caged patches, there was a nonsignificant decline in planthopper recaptures with increasing spider density, suggesting that mortality effects of spiders on planthoppers were weak. In contrast, planthopper recaptures in open patches declined by 85% between the removal and high spider treatments. This significant decline was mostly attributed to spider-induced emigration. We conclude that, at high spider densities, spiders are likely to have a greater impact on planthopper densities through induced emigration than consumption. Because small cordgrass patches support high spider densities and favor high planthopper emigration rates, the nonlethal effects of spiders may play a very important role in determining critical patch size, source-sink properties of cordgrass patches, and the spatial distribution and spread of planthoppers.

Few empirical data exist to examine the influence of regional scale environmental gradients on productivity patterns of plant species. In this paper we analyzed the productivity of several dominant grass species along two climatic gradients, mean annual precipitation (MAP) and mean annual temperature (MAT), in the Great Plains of the United States. We used climatic data from 296 weather stations, species production data from Natural Resource Conservation Service rangeland surveys and a geographic information system to spatially integrate the data. Both MAP and MAT were significantly related to annual above-ground net primary production (ANPP). MAP explained 54 % to 89 % of the variation in ANPP of two C4 short-grasses, Bouteloua gracilis and Buchloë dactyloides, and two C4 tall-grasses, Andropogon gerardii and Schizachyrium scoparium (= Andropogon scoparius). MAT explained 19 % to 41 % of the variation in ANPP of two C4 grasses, B. gracilis and B. dactyloides, and 41 % to 66 % of the variation in ANPP of two C3 grasses, Agropyron smithii and Stipa comata. ANPP patterns for species along both gradients were described by either linear, negative exponential, logistic, normal or skewed curves. Patterns of absolute ANPP (g/m2) for species differed from those of relative ANPP (%) along the MAP gradient. Responses were similar for species with common functional characteristics (e.g. short-grasses, tall-grasses, C3, C4). Our empirical results support asymmetric responses of species to environmental gradients. Results demonstrate the importance of species attributes, type of environmental gradient and measure of species importance (relative or absolute productivity) in evaluating ecological response patterns.

The patches of Paspalum quadrifarium-dominated grasslands found atpresent could be remnants of the vegetation that defined the Pampas landscape inthe past. The mere presence of such physical structures should lead to systemsin which many other species are dependent upon both the autogenic creation ofsurface area for living space and the autogenic and allogenic modulation ofresources controlled by these structures. We carried out amensurative-comparative study in naturally occurring sites dominated byP. quadrifarium that occupy different positions within thelandscape in the Flooding Pampa. We found different species assemblages in thesestructurally homogeneous stands, related to the edaphic and topographicgradients. The comparison with sites from similar positions in the landscapewhere this native tussock-grass was absent showed that the dominance ofP. quadrifarium is a minor determinant of floristicdifferences, which are mainly controlled by abiotic factors. We assigned thesedominated grassland stands to previously delimited vegetation units for theFlooding Pampa grasslands and we compared them with the vegetation unitsassigned, in terms of composite properties of the community that may beindicators of ecosystem processes, such as biological invasions andproductivity. Our results show that this native tussock grass is associated withhigher floristic richness, higher representation of perennials and grasses andlower presence of alien plants. This homogeneous pattern of variation across thevegetation units would suggest that, despite the absence of dramatic changes incommunity composition, the dominance of this tussock grass plays an importantrole in structuring species diversity patterns.[PUBLICATION ABSTRACT]

Because the mat of dead grass stems and leaves, or litter, is a conspicuous feature of grasslands and has been shown to affect various plant processes, I performed a growth chamber experiment on the effect of both grass litter mass (density) and type (species mixes) on emergence of three common prairie grass species. I found that (1) switchgrass (Panicum virgatum) emergence decreased significantly at the highest litter density, but different types of litter had no effect; (2) little bluestem (Schizachyrium scoparium) emergence decreased significantly at the highest litter density and with those litter types that included switchgrass litter; and (3) indiangrass (Sorghastrum nutans) emergence increased significantly at medium density and decreased significantly under its own litter. The results show that the smallest-seeded species had reduced emergence through the litter mat and that amount of litter was more important than type of litter. In conclusion, the full range of litter effects occurred: (1) two species were inhibited by density while the other species was facilitated, and (2) one species was inhibited by litter from another species, one species was inhibited only by its own litter, and one species was unaffected by the species composition of the litter. Finally, the results indicate a potential for grass litter of different species to differentially influence regeneration of tall grass prairie species.