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Native Shrubs (native + shrub)
Selected AbstractsRestoration of a Restinga Sandy Coastal Plain in Brazil: Survival and Growth of Planted Woody SpeciesRESTORATION ECOLOGY, Issue 1 2006Luiz R. Zamith Abstract In this article we report the results of an experiment introducing 17 native shrub and tree species into a Brazilian restinga (i.e., coastal sandy plain vegetation). Restingas have been affected by human impact for about 8,000 years, and human occupation for housing, tourism, and land speculation has recently increased in such a way that there is a need for conservation of remnant patches and restoration of degraded areas throughout the coast to protect biodiversity. Our study site is a remnant located in Rio de Janeiro, the second largest city in the country, and has been subjected in the past to deforestation, man-made fire, and sand extraction. Although trees and shrubs predominantly compose natural restinga vegetation, local vegetation after impact was replaced by an exotic grass cover, which meant a drastic reduction in species richness. Thus, in this experiment we removed the grass cover, introduced shrub and tree species, and monitored survival and growth of 20 plants per species for 2 years. Despite the adversities imposed by the nutrient-poor sandy soil, 70% of the species showed high survival percentage and considerable growth. This report on restoration initiatives in the restingas points out the viability of shrub and tree plantation following exotic grass removal as a strategy to restore Brazilian coastal vegetation. [source] Wide-area estimates of saltcedar (Tamarix spp.) evapotranspiration on the lower Colorado River measured by heat balance and remote sensing methods,,ECOHYDROLOGY, Issue 1 2009Pamela L. Nagler Abstract In many places along the lower Colorado River, saltcedar (Tamarix spp) has replaced the native shrubs and trees, including arrowweed, mesquite, cottonwood and willows. Some have advocated that by removing saltcedar, we could save water and create environments more favourable to these native species. To test these assumptions we compared sap flux measurements of water used by native species in contrast to saltcedar, and compared soil salinity, ground water depth and soil moisture across a gradient of 200,1500 m from the river's edge on a floodplain terrace at Cibola National Wildlife Refuge (CNWR). We found that the fraction of land covered (fc) with vegetation in 2005,2007 was similar to that occupied by native vegetation in 1938 using satellite-derived estimates and reprocessed aerial photographs scaled to comparable spatial resolutions (3,4 m). We converted fc to estimates of leaf area index (LAI) through point sampling and destructive analyses (r2 = 0·82). Saltcedar LAI averaged 2·54 with an fc of 0·80, and reached a maximum of 3·7 with an fc of 0·95. The ranges in fc and LAI are similar to those reported for native vegetation elsewhere and from the 1938 photographs over the study site. On-site measurements of water use and soil and aquifer properties confirmed that although saltcedar grows in areas where salinity has increased much better than native shrubs and trees, rates of transpiration are similar. Annual water use over CNWR was about 1·15 m year,1. Copyright © 2008 John Wiley & Sons, Ltd. [source] Changes in population biology of two succulent shrubs along a grazing gradientJOURNAL OF APPLIED ECOLOGY, Issue 4 2003Corinna Riginos Summary 1Heavy livestock grazing in Namaqualand, South Africa, is threatening the region's unique diversity of succulent shrubs. This is especially true in the communally managed lands, where grazing is centred around fixed enclosures (stockposts) in which animals stay overnight. In this study we set out to determine the effects of a semi-permanent stockpost on the composition of the surrounding vegetation and the mechanisms by which grazing limits the persistence of leaf-succulent shrub populations. 2We used the grazing gradient created by a stockpost to examine the impacts of grazing on vegetation composition and changes in mortality, reproductive output and seedling establishment for the leaf-succulent species Ruschia robusta and Cheiridopsis denticulata. 3Vegetation composition was found to change from a community dominated by the unpalatable shrub Galenia africana at high grazing intensities to a community dominated by the palatable leaf-succulent shrub R. robusta at lower grazing intensities. 4Mortality of the leaf-succulents R. robusta and C. denticulata was high at the sites closest to the stockpost, while fruit production and seedling germination were substantially reduced over distances of 800 m and 2 km for the two species, respectively. Seedling establishment was not limited by either grazing or microsite availability. Thus reduction in reproductive output is the greatest impact of heavy grazing on these two species. 5Synthesis and applications. This study demonstrates that marked zonation in vegetation composition and population biology can develop around a fixed stockpost and that the greatest impact of grazing on the two leaf-succulent species studied is the suppression of flower and fruit production. Consistent suppression of reproductive output could have long-term consequences for the persistence of succulent shrub populations in the heavily grazed communal lands of Namaqualand. We recommend that (i) herders should be encouraged to relocate their stockposts regularly to prevent the development of centres of degradation, and (ii) areas should be relieved periodically of all grazing pressure to allow for successful seed set of native shrubs. [source] Nests, vocalizations, and conservation status of endangered Cochabamba Mountain-Finches (Compsospiza garleppi)JOURNAL OF FIELD ORNITHOLOGY, Issue 3 2009Noemí Esther Huanca ABSTRACT Cochabamba Mountain-Finches (Compsospiza garleppi) are endangered residents of semihumid shrublands in the high Andes, with a range restricted to a few high valleys surrounding the city of Cochabamba, Bolivia. We examined the breeding behavior, feeding ecology, habitat requirements, vocalizations, and conservation status of Cochabamba Mountain-Finches from November 2006 to April 2007. We observed 10 nests of eight pairs, with nests found in a variety of small woody shrubs as well as bunchgrass and a ground bromeliad. Clutches (N= 2) consisted of one or two eggs, and all broods (N= 4) included one or two young. Our observations suggest that Cochabamba Mountain-Finches are not Polylepis specialists as previously thought, and use a diversity of native shrubs often associated with Polylepis woodlands for foraging and nesting. Pairs inhabited modified habitats where native vegetation and woodland edge persisted, but were not observed in closed canopy woodlands. Cochabamba Mountain-Finches frequently foraged on the edges of potato fields in a rural community and, at least occasionally, consumed parts of unearthed tubers. We recorded two previously unknown song types and three types of calls, and one song type was found to be useful for playback surveys. We recommend that future research and conservation actions include thorough surveys using playback to determine population sizes, and that habitat restoration projects focus on maintaining a diversity of native shrubs rather than only Polylepis trees. SINOPSIS Compsospiza garleppi es una especie residente en peligro de las tierras arbustivas semihúmedas de los altos Andes, con un rango restringido a unos pocos valles en los alrededores de la ciudad de Cochabamba, Bolivia. Nosotros examinamos el comportamiento reproductivo, la ecología alimentaria, los requerimientos de hábitat, vocalizaciones y estado de conservación de Compsospiza garleppi desde Noviembre 2006 hasta Abril 2007. Observamos 10 nidos de ocho parejas, los nidos fueron encontrados en una variedad de pequeños arbustos al igual que en montones de pastos y bromelias de suelo. La nidadas (N= 2) consistieron de uno o dos huevos y uno o dos polluelos (N= 4). Nuestras observaciones sugieren que Compsospiza garleppi no es un especialista de Polylepis como se había pensado anteriormente, y usa una diversidad de arbustos nativos asociados con bosques de Polylepis para buscar alimento y anidar. Se encontraron parejas en hábitat modificado en donde la vegetación nativa y los bordes de bosque persistieron, pero no fueron observadas en bosques con un dosel cerrado. Compsospiza garlepp busco alimento frecuentemente en los bordes de plantaciones de papa en una comunidad rural y, ocasionalmente, consumió partes de tubérculos desenterrados. Nosotros grabamos dos cantos no descritos anteriormente y tres tipos de llamados, un tipo de los cantos fue beneficioso para estudios de playback. Nosotros recomendamos que futuros estudios y acciones de conservación usen playback como herramienta para realizar censos minuciosos para determinar tamaños poblacionales, y que proyectos de restauración de hábitat se enfoquen en el mantenimiento de la diversidad de arbustos nativos en vez de únicamente mantener árboles de Polylepis. [source] Shrubs as ecosystem engineers in a coastal dune: influences on plant populations, communities and ecosystemsJOURNAL OF VEGETATION SCIENCE, Issue 5 2010J. Hall Cushman Abstract Question: How do two shrubs with contrasting life-history characteristics influence abundance of dominant plant taxa, species richness and aboveground biomass of grasses and forbs, litter accumulation, nitrogen pools and mineralization rates? How are these shrubs , and thus their effects on populations, communities and ecosystems , distributed spatially across the landscape? Location: Coastal hind-dune system, Bodega Head, northern California. Methods: In each of 4 years, we compared vegetation, leaf litter and soil nitrogen under canopies of two native shrubs ,Ericameria ericoides and the nitrogen-fixing Lupinus chamissonis, with those in adjacent open dunes. Results: At the population level, density and cover of the native forb Claytonia perfoliata and the exotic grass Bromus diandrus were higher under shrubs than in shrub-free areas, whereas they were lower under shrubs for the exotic grass Vulpia bromoides. In contrast, cover of three native moss species was highest under Ericameria and equally low under Lupinus and shrub-free areas. At community level, species richness and aboveground biomass of herbaceous dicots was lower beneath shrubs, whereas no pattern emerged for grasses. At ecosystem level, areas beneath shrubs accumulated more leaf litter and had larger pools of soil ammonium and nitrate. Rates of nitrate mineralization were higher under Lupinus, followed by Ericameria and then open dune. At landscape level, the two shrubs , and their distinctive vegetation and soils , frequently had uniform spatial distributions, and the distance separating neighbouring shrubs increased as their combined sizes increased. Conclusions: Collectively, these data suggest that both shrubs serve as ecosystem engineers in this coastal dune, having influences at multiple levels of biological organization. Our data also suggest that intraspecific competition influenced the spatial distributions of these shrubs and thus altered the distribution of their effects throughout the landscape. [source] Love of Nurse Plants is Not Enough for Restoring Oak Forests in a Seasonally Dry Tropical EnvironmentRESTORATION ECOLOGY, Issue 5 2009Ernesto I. Badano Abstract The highest concentration of oak species in the world occurs in Mexico, but human activities have strongly degraded these oak forests. Mexican oaks have high economic, social, and cultural value, and restoring these forests is of paramount importance for the people of Mexico. Here, we propose a method for restoring oak forests using native shrubs that colonize degraded areas as nurse plants for oak seedlings. To test the viability of this proposal, seedling transplant experiments were performed in a degraded area near a protected oak forest relict. Two pioneer shrubs were identified as potential nurse species: Mimosa luisana and Senecio sp. The target oak species was Quercus castanea. Oak seedlings were located beneath the canopies of both shrubs and in the surrounding area without shrub cover. Water is a limiting resource for oak establishment in seasonally dry environments; therefore, we included irrigation systems in our experimental design to determine whether the combination of nurse plants plus watering led to higher rate of survival than the presence of nurse species alone. Seedling survival without watering was less than 20% both beneath nurse species and in the surrounding habitat. When water was supplied, survival rate beneath nurse species increased up to 58% while survival in the surrounding habitat did not differ from that observed in treatments without watering. Our results indicate that survival rate of oak seedlings is increased by the presence of nurse plants only when water is supplied. This suggests that restoration of oak forests in these degraded areas requires both nurse plants and watering. [source] Fire frequency influences composition and structure of the shrub layer in an Australian subcoastal temperate grassy woodlandAUSTRAL ECOLOGY, Issue 2 2009PENNY J. WATSON Abstract Little is known about the relationship between fire regimes and plant diversity in Australia's temperate grassy woodlands. The effect of fire frequency on shrubs in grassy woodland remnants across Western Sydney's Cumberland Plain was examined. Shrub species richness and composition were compared in sites that had experienced a high, moderate or low frequency of fire over the previous 20 years. Nine sites were surveyed, three in each fire frequency category; most sites, including all low-fire-frequency sites, had burnt 9,36 months prior to sampling. Fire frequency had a profound effect on the composition and structure of the shrub layer. Per cent frequency and density of the prickly shrub Bursaria spinosa (Pittosporaceae) was considerably higher in low-fire-frequency sites than where fires had occurred at least once a decade. In sites where fire had been absent for decades prior to a recent fire, this species dominated the landscape, while elsewhere it occurred as clumps in a grassy matrix. Per cent frequency of other native shrubs, particularly obligate seeders, was greatest at moderate fire frequencies. Exotic shrubs were recorded most often where fire had been rare. While ordination clearly separated out the low-fire-frequency sites, complete separation between high- and moderate-fire-frequency blocks was not achieved. The increase in Bursaria in the absence of fire mirrors the encroachment of woody plants into a range of grassy ecosystems around the world. The sensitivity of obligate seeder species, many of them short-lived legumes with fire-cued seeds, to both very frequent and very infrequent fire shows the vulnerability of these species to extreme fire regimes, despite the safeguards conferred by hard-seededness. Competition from Bursaria, as well as loss of viable seed in the soil, may have contributed to the low frequency of these species after a long inter-fire interval. [source] | |||||||||||||