نتایج جستجو برای: shrub invasion

تعداد نتایج: 77759  

Journal: :Journal of environmental management 2012
Kurt H Riitters James D Wickham Timothy G Wade Peter Vogt

The conservation value of natural vegetation is degraded by proximity to anthropogenic land uses. Previous global assessments focused primarily on the amount of land protected or converted to anthropogenic uses, and on forest vegetation. Comparative assessments of extant vegetation in terms of proximity to anthropogenic land uses are needed to better inform conservation planning. We conducted a...

2016
C Guillermo Bueno Scott N Williamson Isabel C Barrio Ágústa Helgadóttir David S HiK

In tundra ecosystems, bryophytes influence soil processes directly and indirectly through interactions with overstory shrub species. We experimentally manipulated moss cover and measured seasonal soil properties and processes under two species of deciduous shrubs with contrasting canopy structures, Salix planifolia pulchra and Betula glandulosa-nana complex. Soil properties (seasonal temperatur...

2009

Question: Does the proximity of shrubs affect seasonal water stress of young Austrocedrus chilensis trees (a native conifer of the Austral Temperate Forest of South America) in xeric sites? Location: A. chilensis xeric forest in northwest Patagonia, Argentina. Methods: We examined the dependence of predawn twig water potential on tree development (seedling to adult) and proximity to nurse shrub...

2017
Saixiyala Ding Yang Shudong Zhang Guofang Liu Xuejun Yang Zhenying Huang Xuehua Ye

The formation of fertility islands by shrubs increases soil resources heterogeneity in thicketization-grasslands. Clonal plants, especially rhizomatous or stoloniferous clonal plants, can form large clonal networks and use heterogeneously distributed resources effectively. In addition, shrubs, especially spiny shrubs, may also provide herbaceous plants with protection from herbivores, acting as...

2015
Adam T Naito David M Cairns

Recent increases in deciduous shrub cover are a primary focus of terrestrial Arctic research. This study examined the historic spatial patterns of shrub expansion on the North Slope of Alaska to determine the potential for a phase transition from tundra to shrubland. We examined the historic variability of landscape-scale tall shrub expansion patterns on nine sites within river valleys in the B...

2015
James L. Hanula Scott Horn Joseph J. O’Brien

Two conservation goals of the early 20th century, extensive reforestation and reduced wildfire through fire exclusion, may have contributed to declining pollinator abundance as forests became denser and shrub covered. To examine how forest structure affects bees we selected 5 stands in each of 7 forest types including: cleared forest; dense young pines; thinned young pines; mature open pine wit...

2011
Suzanne M. Owen Carolyn Hull Sieg Catherine A. Gehring

Rehabilitation of downy brome–infested shrublands is challenging once this invasive grass dominates native communities. The effectiveness of imazapic herbicide in reducing downy brome cover has been variable, and there is uncertainty about the impacts of imazapic on native species. We used a before-after-control-impact (BACI) field experiment and greenhouse studies to (1) determine if imazapic ...

2016
Veronika Braunisch Patrick Patthey Raphaël Arlettaz

In many cultural landscapes, the abandonment of traditional grazing leads to encroachment of pastures by woody plants, which reduces habitat heterogeneity and impacts biodiversity typical of semi-open habitats. We developed a framework of mutually interacting spatial models to locate areas where shrub encroachment in Alpine treeline ecosystems deteriorates vulnerable species' habitat, using bla...

2004
G. M. ROGERS

Relationships between composition of secondary vegetation and environment were studied in central North Island, New Zealand. A classification procedure was used to identify broad compositional groups which included forest, broadleaved scrub, shrub-fernland, sclerophyllous scrub and shrubland, and tussock-shrubland. Generalised additive models (GAMs) were used to examine relationships between sp...

Journal: :گوارش 0
homeyra ommati mitra ahadi hasan vosoghinia elham mokhtari amirmajdi nema mohammadian roshan mohammadreza farzanehfar

there is still been no report of splenic involvement in the wake of colon cancer. in this case, air was seen in the spleen and liver following the penetration of colon cancer to the continuous spleen. colon cancers always do not present with clear and common symptoms. some times with a non-specific and uncommon symptoms and signs present that would be amazed physicians and researchers. it is ve...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید