Changes in land cover and vegetation carbon stocks in Andalusia, Southern Spain (1956-2007)

Land use has significantly changed during the recent decades at global and local scale, while the importance of ecosystems as sources/sinks of C has been highlighted, emphasizing the global impact of land use changes. Land use changes can increase C loss rates which are extremely difficult to reverse, in the short term, opposite to organic carbon (OC) which accumulates in soil in the long-term. The aim of this research is to improve and test methodologies to assess land cover change (LCC) dynamics and temporal and spatial variability in C stored in vegetation at a wide scale. LCCs between 1956 and 2007 in Andalusia (Southern Spain) were selected for this pilot study, assessed by comparison of spatial data from 1956 to 2007 and were reclassified following land cover flows (LCFs) reported in major areas in Europe. Carbon vegetation densities were related to land cover, and C vegetation stocks for 1956 and 2007 were calculated by multiplying C density for each land cover class with land cover areas. The study area has supported important changes during the studied period with significant consequences for vegetation C stocks, mainly due to afforestation and intensification of agriculture, resulting in a total vegetation C stock of 156.08 Tg in 2007, with an increase of 17.24 Tg since 1956. This study demonstrates the importance of LCC for C sequestration in vegetation from Mediterranean areas, highlighting possible directions for management policies in order to mitigate climate change as well as promoting land conservation. The methodologies and information generated in this project will be a useful basis for designing land management strategies helpful for decision makers.     

Drivers of floristic change in large cities - A case study of Frankfurt/Main (Germany)

The main aim of the study is to reconstruct diversity of established vascular plants between 1800 and 2000 in today's area of Frankfurt/Main (Germany, Hesse) - using historical literature, herbarium vouchers, and a recent landscape survey - and to interpret changes (extinctions and gains) in the light of land use changes (drivers). Species numbers declined from 1800 (1232 species; 926 indigenous-228 archaeophytes-78 neophytes) to 1900 (1200 species; 871-219-110), and 2000 (1107 species; 698-166-252). The most important drivers for the loss of species (319 spp.) are use of fertilizers and herbicides, abandonment of wood pastures, abandonment and melioration of wet grassland. Most species gained (193 spp.) were intentionally introduced as ornamentals. Among the neophytes naturalized after 1800, short-living plants adapted to dry open habitats dominate. Plants using the C4 carbon fixation pathway (C4-plants) are predominantly neophytes. Drivers for the loss of species are general changes in land use. Nature conservation slackened the loss of species in the last decades; today about 3% of the vascular plants are conservation dependent. Comparatively high rates of short-living plants adapted to dry open habitats and C4-plants among neophytes indicate a warming of the climate. We expect a rising number of garden escapes. Furthermore, the flora will become more dependent on conservation measures. Remnants of now obsolete forms of land use like low nutrient grassland shall be integrated into parks and urban open spaces.     

Spatio-temporal trend analysis of long-term development patterns (1900-2030) in a Southern Appalachian County

Many mountainous areas in the U.S. have experienced significant changes in residential development patterns over the past century, in large part due to changing economies and in-migration from outsiders seeking the scenic resources of these areas. To evaluate changes in the Southern Appalachian mountain region, we reconstructed building and road locations in Macon County, North Carolina, since 1906 from historic maps, aerial photographs, county parcel records and emergency response program data. We used these data to analyze growth trends using spatio-temporal classification and quantile regression analysis. We also forecast future development patterns through 2030 using a multi-step model incorporating population growth projections, extrapolations of recent development density trends, and spatial logistic regression models. We characterize new development in the county as primarily rural from 1906 to 1960, exurban from 1960 to 1975 and increasingly suburban since 1975. While the rate of population growth and new building construction peaked in the 1980s, the total road length and rate of development in forested areas continued to increase from 1990 to 2009. We forecast that through 2030 approximately 75% of new buildings will be constructed at urban and suburban densities and that 67% of all new buildings will be constructed in forested areas. In addition to establishing the utility of using spatial analysis to draw together disparate data sources to understand urbanization over long time scales, this analysis identifies trends that have important implications for land-use planning, hydrology, forest management, and wildlife conservation.     

Design and application of a stratified sampling strategy to study the regional distribution of cyanobacteria (Ile-de-France, France)

This study describes the design and application of a stratified sampling strategy of waterbodies to assess and analyze the distribution of cyanobacteria at a regional scale (Ile-de-France, IDF). Ten groups of hydrographical zones were defined within the IDF on the basis of their anthropogenic and geomorphologic characteristics. Sampling effort (n = 50) was then randomly allocated according to the number of waterbodies in each group. This sampling strategy was tested in August 2006, using a field probe to estimate total phytoplankton as well as cyanobacteria biomasses. The sampled waterbodies exhibited a wide range of phytoplankton (<1-375 μg equiv. Chla L⁻¹) and cyanobacteria biomasses (<1-278 μg equiv. Chla L⁻¹). 72% of the waterbodies in the IDF were classified as eutrophic (42% hypereutrophic), and 24% of the sites studied were dominated by cyanobacteria. Waterbodies connected to hydrographical networks (n = 26) showed significantly higher total (p < 0.0001; 3.5 times greater) and cyanobacterial (p < 0.001, 3.2 times greater) biomasses than the isolated ones (n = 24). No significant overall relationship was found through contingency analysis between waterbody trophic status and global land use categories (urban, periurban, and rural) within their hydrographical zones. However, concerning the waterbodies linked to hydrographical networks, the percentage of land covered by forest appeared as a good indicator of phytoplankton and cyanobacterial biomasses. This observation may be a consequence of lower amounts of nutrients being discharged into waterbodies from highly forested hydrological zone than from urban and/or agricultural areas. Our results illustrate a successful means of selecting representative waterbodies to conduct a regional assessment of cyanobacteria distribution using accessible GIS analyses.