In rare plants that often occur in small or isolated populations the probability of selfing between close relatives is increased as a consequence of demographic stochasticity. The mode of pollination ...(selfing, outcrossing) may have considerable effects on seed traits and offspring performance and hence potential viability. Since current efforts aiming at the restoration of floodplain grasslands through the transfer of plant material from species-rich source stands may lead to the establishment of initially small populations consisting of founders from different populations, the present paper experimentally investigated the effects of pollen source and floral types (i.e. chasmogamous (CH) and cleistogamous (CL) flowers) on seed traits and offspring performance in three highly endangered violet species (
Viola elatior,
V. pumila,
V. stagnina) of these grasslands. We estimated inbreeding depression and tested the performance of selfed and outcrossed offspring in two microbial environments, i.e. in soil inoculated with (i) non-sterile substrate from the same species (‘home’-conditions) and (ii) sterilised substrate.
Plants produced more CL capsules than CH flowers. Pollinator exclusion had only small effects on CH seed production. CL seeds had a significantly lower mass per seed than CH seeds. This may be related to constraints in allocation or environmental conditions. Seedling growth was reduced in plants grown under ‘home’-conditions as compared to control soils. Under ‘home’-conditions, relative fitness of selfed seedlings of
V. stagnina was significantly higher than that of crossed progeny. Our results suggest that high genetic differentiation among populations as a consequence of isolation may result in outbreeding depression, e.g., through biochemical or physiological incompatibilities between genes or the breaking of coadapted gene complexes. In
V. stagnina, offspring fitness differed considerably between environments, but in general we found no indications for inbreeding depression in these rare species.
Bei seltenen Arten, die oft in kleinen oder isolierten Populationen vorkommen, ist die Wahrscheinlichkeit von Selbstbestäubung durch verwandte Individuen als Folge demographischer Stochastizität erhöht. Die Art der Blütenbestäubung kann erhebliche Auswirkungen auf Samenmerkmale und die Fitness der Nachkommen und daher auf die Lebensfähigkeit von Populationen haben. Zur Zeit durchgeführte Maßnahmen zur Wiederherstellung von Stromtalwiesen durch die Übertragung von Pflanzenmaterial aus artenreichen Spenderbeständen können zur Entstehung von anfangs kleinen, aus Individuen verschiedener Spenderbestände zusammengesetzten Populationen führen. Daher untersucht die vorliegende Arbeit die Effekte unterschiedlicher Pollenquellen und des Blütentyps (chasmogame (CH) und kleistogame (CL) Kapseln) auf Samenmerkmale und die Fitness der Nachkommen von drei stark gefährdeten Veilchenarten (
V. elatior,
V. pumila und
V. stagnina) dieser Habitate. Wir ermittelten den Grad der Inzuchtdepression und untersuchten das Keimlingswachstum von Nachkommen aus Selbst- und Fremdbestäubung unter Bedingungen, die sich in Hinblick auf die mikrobielle Umwelt unterschieden, d.h. in Boden, der mit (i) nicht-sterilem Substrat derselben Art (‘Heimat’-Bedingungen) und (ii) sterilisiertem Substrat beimpft war. Die Veilchen produzierten mehr CL Kapseln als CH Blüten. Der experimentelle Ausschluss von Bestäubern hatte nur geringe Auswirkungen auf die Produktion von CH Samen. CL Samen hatten im Mittel ein signifikant geringeres Gewicht als CH Samen. Dies kann mit unterschiedlicher Allokation von Ressourcen oder unterschiedlichen Umweltbedingungen bei der Samenbildung zusammenhängen. Das Keimlingswachstum war geringer unter ‘Heimat’-Bedingungen als unter Kontrollbedingungen. Unter ‘Heimat’-Bedingungen war bei
V. stagnina die relative Fitness von Keimlingen aus Selbstbestäubung signifikant höher als die von fremdbestäubten Nachkommen. Unsere Ergebnisse legen nahe, dass ein hoher Grad genetischer Differenzierung als Folge der Isolation der Populationen dieser Art zu Kreuzungsdepression, z. B. durch biochemische oder physiologische Inkompatibilität zwischen Genen oder den Bruch koadaptierter Genkomplexe, führen könnte. Die Fitness von Nachkommen von
V. stagnina variierte stark zwischen den Bodenbehandlungen, aber generell fanden wir keine Hinweise auf Inzuchtdepression bei den untersuchten seltenen Veilchenarten.
Surface mining alters the water regime not only locally, but also regionally. The reduced brown coal mining in the south-east of the state Brandenburg (Germany) leads to decreasing river discharge ...and consequently to a shortage in the water supply. Land use change is one possible option to counteract this development. In this simulation study, we explored the impact of temporary and permanent set-aside of arable land on Brandenburg’s regional water balance. Temporary and permanent set-aside were considered as major measures towards deintensification of agriculture. Simulations were performed using the regional ecohydrological model SWIM, which integrates hydrological processes, vegetation growth, erosion and nutrient dynamics. The model was used to simulate the consequences of different land use change scenarios on main components of the regional water balance. Changes in the use of arable land altered clearly its water balance. The impact of these changes on the regional water balance for Brandenburg did not exceed ±10% for its single components. Opposite tendencies were established in the simulations by contrasting effects of temporary and permanent set-aside of arable cropland. While temporary set-aside increased runoff from the whole area up to 6.7% due to lower evapotranspiration and higher soil moisture in arable land, the conversion of agricultural land within river corridors to meadows had an opposite effect on regional runoff (6.9% decrease) due to higher water retention coefficients and higher evapotranspiration losses. Therefore, only temporary set-aside may compensate to some extent for the anticipated decrease in river discharge.
In view of the state of hydromorphological preservation of river corridors in the Slovenian hydrographic network and because of demands imposed by domestic and European legislature concerning water ...resource management and environmental protection, certain sections of rivers and streams that were for various reasons regulated in the past, will have to be rehabilitated. Permanent solutions to such issues demand careful planning of rehabilitation on suitable sections of rivers and streams, adequate positioning within physical planning acts, as well as streamlined administrative procedures and devised maintenance of rehabilitation areas. Because the process demands the return of formerly taken water surfaces into the domain of water ecosystems and dynamics of hydromorphological processes, and consequentially maintenance of regained surfaces, the public becomes an important factor, which is a position, granted by domestic and European laws. Last, but not least, successful execution of rehabilitation of water corridors, besides planning, administration and consistent public participation, demands knowledge about good practices of project management, as well as technical execution of such projects.
Principles and guidelines are outlined for the development and implementation of integrated design approaches to achieve sustainable levels of environmental enhancement in urban floodways and ...corridors. In-channel bioengineenng combined with out-of-channel landscaping offers a range of opportunities for conservation, recreation and amenity as well as providing basic flood and pollution control. In addition, integrated local-scale restoration and remediation is compatible with holistic concepts of wider catchment management as well as supporting local community objectives of land enhancement. Approaches to watercourse design are described and key functional relationships identified for the achievement of integrated landscape design.
Researchers have debated the effect of the Trans-Alaska Pipeline (TAP) and associated developments to caribou (Rangifer tarandus) of the central Arctic herd (CAH) since the 1970s. Several studies ...have demonstrated that cows and calves of the CAH avoided the TAP corridor because of disturbance associated with the pipeline, whereas others have indicated that female caribou of the CAH avoided riparian habitats closely associated with the pipeline. This avoidance was explained as a predator-avoidance strategy. We investigated the relation between female caribou and grizzly bear (Ursus arctos) use of river corridors on the yet undisturbed calving grounds of the Porcupine caribou herd (PCH) in northeastern Alaska. On the coastal plain, caribou were closer to river corridors than expected (P = 0.038), but bear use of river corridors did not differ from expected (P = 0.740). In the foothills, caribou use of river corridors did not differ from expected (P = 0.520), but bears were farther from rivers than expected (P = 0.001). Our results did not suggest an avoidance of river corridors by calving caribou or a propensity for bears to be associated with riparian habitats, presumably for stalking or ambush cover. We propose that PCH caribou reduce the risks of predation to neonates by migrating to a common calving grounds, where predator swamping is the operational antipredator strategy. Consequently, we hypothesize that nutritional demands, not predator avoidance strategies, ultimately regulate habitat use patterns (e.g., use of river corridors) of calving PCH caribou.
Lemur Biogeography Ganzhorn, Jörg U.; Goodman, Steven M.; Nash, Stephen ...
Primate Biogeography
Book Chapter
Madagascar is the fourth largest island in the world and is inhabited by a rich fauna of endemic lemuriform primates. Recent morphological and molecular, studies indicate that the biogeography of ...Malagasy lemurs is far more complex than previously thought. Small scale patterns of vegetation and river barriers seem to have been more important than large present-day barriers. Rivers can act as both barriers and corridors. Most significantly, there is increasing evidence that the major phylogenetic distinctions are between northern and southern taxa rather than between eastern and western forms. Lemur systematics is still in a state of ongoing revision, and additional surveys of poorly-known regions are needed to understand the complex biogeography of Malagasy primates.
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