The Experts below are selected from a list of 5052 Experts worldwide ranked by ideXlab platform
Julie E Korb - One of the best experts on this subject based on the ideXlab platform.
-
soil seed banks in pinus ponderosa forests in arizona clues to site history and restoration potential
Applied Vegetation Science, 2005Co-Authors: Julie E Korb, Judith D Springer, Stephanie R Powers, Margaret M MooreAbstract:Question: How does the relationship between the viable soil seed bank Species composition and the above-ground vegetation in northern Arizona Pinus ponderosa forests differ under varying historical land use disturbances (low, intermediate, high)? Is above-ground vegetation correlated to the viable soil seed bank immediately following soil disturbance from restoration thinning treatments? Location: Northern Arizona, USA. Methods: Soil seed bank samples were taken along replicated transects and collected with a 5-cm diameter bulk density hammer. Samples included a 5 -cm diameter O-horizon sample (at varying depths) plus the underlying mineral soil to a depth of 5 c m . The seedling emergent method was used to quantify seed bank Species composition and density. The herbaceous and shrub plant community was quantified along the same transects using the point intercept method. Results: Early-successional or Ruderal Species were common in the soil seed bank at all three disturbance sites. Non-native Species, notably Verbascum thapsus, were more numerous (up to 940 seeds/m2) under high disturbance with overgrazing and logging, and less common or absent under low disturbance. Most viable seeds were found in the O-horizon and the upper 5 cm of mineral soil; there was little correlation between Species in the soil seed bank and the above-ground vegetation. Conclusions: We recommend that restoration plans be geared toward minimizing activities, such as severe soil disturbance, that may promote the spread of non-native invasive Species, and that manual seeding be explored as an option to restore plant Species diversity and abundance.
-
slash pile burning effects on soil biotic and chemical properties and plant establishment recommendations for amelioration
Restoration Ecology, 2004Co-Authors: Julie E Korb, Nancy Collins Johnson, Wallace W CovingtonAbstract:Ponderosa pine forest restoration consists of thinning trees and reintroducing prescribed fire to reduce unnaturally high tree densities and fuel loads to restore ecosystem structure and function. A current issue in ponderosa pine restoration is what to do with the large quantity of slash that is created from thinning dense forest stands. Slash piling burning is currently the preferred method of slash removal because it allows land managers to burn large quantities of slash in a more controlled environment in comparison with broadcast burning slash. However burning slash piles is known to have adverse effects such as soil sterilization and exotic Species establishment. This study investigated the effects of slash pile burning on soil biotic and chemical variables and early herbaceous succession on burned slash pile areas. Slash piles were created following tree thinning in two adjacent approximately 20-ha ponderosa pine (Pinus ponderosa) restoration treatments in the Coconino National Forest near Flagstaff, Arizona. We selected 30 burned slash pile areas and sampled across a gradient of the burned piles for arbuscular mycorrhizal (AM) propagule densities, the soil seed bank, and soil chemical properties. In addition, we established five 1-m 2 plots in each burned pile to quantify the effect of living soil (AM inoculum) and seeding amendments on early herbaceous succession in burned slash pile areas. The five treatments consisted of a control (no treatment), living soil (AM inoculum) amendment, sterilized soil (no AM inoculum) amendment, seed amendment, and a seed/soil (AM inoculum) amendment. Slash pile burning nearly eliminated populations of viable seeds and AM propagules and altered soil chemical properties. Amending scars with native seeds increased the cover of native forbs and grasses. Furthermore adding both seed and living soil more than doubled total native plant cover and decreased Ruderal and exotic plant cover. These results indicate that seed/soil amendments that increase native forbs and grasses may enhance the rate of succession in burned slash pile areas by allowing these Species to outcompete exotic and Ruderal Species also establishing at the site through natural regeneration.
Petr Pysek - One of the best experts on this subject based on the ideXlab platform.
-
constraints to native plant Species establishment in coastal dune communities invaded by carpobrotus edulis implications for restoration
Biological Conservation, 2013Co-Authors: Ana Novoa, Luis Gonzalez, Lenka Moravcova, Petr PysekAbstract:Carpobrotus edulis, an alien chamaephyte Species from South Africa, severely invades and represents one of the greatest threats to coastal plant biodiversity in regions with Mediterranean climate worldwide. Although actions have been promoted to eliminate it, these efforts have failed to restore dunes to the natural, preinvasion stage. We tested, by means of field and laboratory experiments, how C. edulis alters soil chemistry by causing residual effects on soil, and examined whether these effects decrease germination, survival and growth of a common native chamaephyte dune Species Malcolmia littorea. We also recorded Species diversity to find out which Species can establish after the removal of the invasive C. edulis. To link both measures, we monitored changes in soil characteristics over 1 year after the removal of the invader, by analyzing both soil chemical properties and extracellular enzymes. C. edulis lowers soil pH, Ca and Na content and increases organic content, salinity and nitrogen and phosphorus concentration. The effects of the invader on the growth of M. littorea during the first growing season were very weak, despite strong negative effects in the early stages of this Species’ population development that decreased total germination and survival. Overall, the soil characteristics and activity of the microbial community tend to recover back to preinvasion conditions in plots from which C. edulis is removed. In contrast, the establishment of native dune vegetation is constrained, as indicated by lower Species diversity in restored compared to non-invaded areas. This is because regenerating dunes are occupied by opportunistic Ruderal Species that compete with native dune plants of conservation value and restrict their establishment.
Ana Novoa - One of the best experts on this subject based on the ideXlab platform.
-
constraints to native plant Species establishment in coastal dune communities invaded by carpobrotus edulis implications for restoration
Biological Conservation, 2013Co-Authors: Ana Novoa, Luis Gonzalez, Lenka Moravcova, Petr PysekAbstract:Carpobrotus edulis, an alien chamaephyte Species from South Africa, severely invades and represents one of the greatest threats to coastal plant biodiversity in regions with Mediterranean climate worldwide. Although actions have been promoted to eliminate it, these efforts have failed to restore dunes to the natural, preinvasion stage. We tested, by means of field and laboratory experiments, how C. edulis alters soil chemistry by causing residual effects on soil, and examined whether these effects decrease germination, survival and growth of a common native chamaephyte dune Species Malcolmia littorea. We also recorded Species diversity to find out which Species can establish after the removal of the invasive C. edulis. To link both measures, we monitored changes in soil characteristics over 1 year after the removal of the invader, by analyzing both soil chemical properties and extracellular enzymes. C. edulis lowers soil pH, Ca and Na content and increases organic content, salinity and nitrogen and phosphorus concentration. The effects of the invader on the growth of M. littorea during the first growing season were very weak, despite strong negative effects in the early stages of this Species’ population development that decreased total germination and survival. Overall, the soil characteristics and activity of the microbial community tend to recover back to preinvasion conditions in plots from which C. edulis is removed. In contrast, the establishment of native dune vegetation is constrained, as indicated by lower Species diversity in restored compared to non-invaded areas. This is because regenerating dunes are occupied by opportunistic Ruderal Species that compete with native dune plants of conservation value and restrict their establishment.
Xiaoli Liu - One of the best experts on this subject based on the ideXlab platform.
-
dynamics of Ruderal Species diversity under the rapid urbanization over the past half century in harbin northeast china
Urban Ecosystems, 2014Co-Authors: Xiaoshuang Chen, Weibo Wang, Hong Liang, Xiaoli LiuAbstract:Urbanization has resulted in obvious changes in plant Species diversity. We analyzed the dynamics of Ruderal Species diversity in Harbin over the past half century using historical data collected in 1955 and data of the present spatial distribution in 2010–2011. The results show that, the number of Ruderal Species decreased from 611 to 175 with remarkable tendency of decreasing in perennial Species and increasing in winter annual Species in the past half century, which caused the shift of life form spectrum from perennial mono-dominant type to summer annual and perennial co-dominant type. Meanwhile, the proportion of tropical originated Species increased and the proportion of temperate originated Species decreased which were considered to relate with the increase of temperature in urban area during the past half century. Moreover, there was a distinct decrease of the proportion of aquatic and hygrophytic Ruderal Species while an increase of mesic and xeric Ruderal Species which suggested a drought trend in urban habitats that consistent with the change of land use characterized as decrease of natural water bodies and wetlands and increase of urban land. Comparison of Ruderal Species along urbanization gradient also got the similar results with the above results from analysis on temporal scales and confirmed the effect of urbanization on decreasing plant richness. Our results suggested that land use change combined with its effect on temperature and disturbance regimes in urban habitats preferred Species with short life span, high drought tolerance, fast growth rates and high seed yields.
Laura M Carranza - One of the best experts on this subject based on the ideXlab platform.
-
the impact of human pressure on landscape patterns and plant Species richness in mediterranean coastal dunes
Plant Biosystems, 2016Co-Authors: Marco Malavasi, Riccardo Santoro, Maurizio Cutini, Alicia Teresa Rosario Acosta, Laura M CarranzaAbstract:We analyze the spatial patterns of natural dune cover patches and their plant richness, comparing coastal sites with different levels of human pressure in central Italy. We created a detailed land cover map of dune sites. The spatial pattern of natural dune cover types was characterized by computing a set of patch-based metrics. To quantify patch plant richness, we used 16 m2 vegetation plots, randomly distributed on coastal dune cover types. For each patch, the richness of the entire pool of Species and of three guilds (i.e., typical dune, Ruderal, and alien Species) was considered. We compared different levels of human pressure on coastal dunes focusing on pattern metrics and floristic information by using the nonparametric Kruskal–Wallis test. In sites with high human pressure, we have observed a general simplification in the natural dune spatial pattern and a decline of plant richness but with a specific response for each cover type. Alien and Ruderal Species presented low richness in all patches. In ...
