Egy inváziós faj, a Solidago gigantea Aiton által kolonizált mocsárrétek diverzitása és fajkompozíciós koordináltsága

Számos vizsgálat történt korábban a Solidago gigantea Aiton elterjedtségével, ökológiai és növényélettani tulajdonságaival kapcsolatban, azonban a faj inváziójának cönológiai következményei kevéssé ismertek. Mocsárréti társulások diverzitását és belső koordináltságát hasonlítottuk össze, magas aranyvesszővel különböző mértékben fertőzött területeken. Hat, eltérő mértékben kolonizált gyepterületet vizsgáltunk, melyek közül kettő referenciaterületként is szolgált. Állományonként 8‒8 db 5 m hosszú transzszektet mintavételeztünk. Ezek mentén 100 db egymást érő 5 cm × 5 cm-es mikrokvadrátban rögzítettük a fajok jelenlétét. Az állományok belső szervezettségét és koordináltságát a diverzitás és az egyenletesség állományon belüli szóródásával (CV%) és a mintavételi egységek állományon belüli átlagos cönológiai hasonlóságával jellemeztük. A S. gigantea gyakorisága jelentősen különbözött a mintaterületeken, és mennyiségének növekedésével összefüggésben változtak az állományok cönológiai jellemzői: csökkent a diverzitás és a koordináltság. Különböző cönológiai jellemzőket összehasonlítva megállapítható, hogy az átlagos viselkedést kifejező alfa diverzitás és egyenletesség kevésbé érzékenyen mutatják az inváziós faj okozta degradációt, mint e jellemzők béta diverzitást is jelentő relatív szórása (CV%). Eredményeink szerint a cönológiai koordináltság állományon belüli változása (jelen esetben csökkenése) egyszerűen mérhető és jó indikátora az inváziós faj okozta cönológiai változásoknak

Evaluating alternative mowing regimes for conservation management of Central European mesic hay meadows: A field experiment

<p>Conservation status of hay meadows highly depends on their management. The main goal of this study was to assess the efficiency of different mowing regimes in maintenance of plant species richness and diversity of mesic hay meadows. The field experiment was carried out on a species rich, mesic hay meadow in Western Hungary. We evaluated the effects of four alternative types of management on the plant community after 7 years of continuous treatment: (1) mowing twice a year, typical traditional management, (2) mowing once a year in May, most practised currently by local farmers, (3) mowing once a year in September, often proposed for conservation management and (4) abandonment of mowing. Traditional mowing resulted in significantly higher number and higher diversity of vascular plant species than other mowing regimes. Mowing twice a year was the only efficient way to control the spread of the invasive <i>Solidago gigantea,</i> and mowing in September was more successful in it than mowing in May. We conclude that the traditional mowing regime is the most suitable to maintain botanical diversity of mesic hay meadows; however, other regimes should also be considered if certain priority species are targeted by conservation.</p

Solving the conflict between intensive and extensive approaches: transect based sampling design for comparative studies on fine scale plant community organization

Background and Aims: Non-equilibrium ecological paradigm considers plant community as a complex dissipative system, which calls for a methodology with explicit representation of spatiotemporal patterns. However, recording vegetation patterns at this fine scale is time consuming and labour intensive. In contrast, understanding general rules of community organization and vegetation structure would require large number of comparative case studies. There is a clear trade-off between these intensive and extensive aspects in ecological applications. Here, we explore how field sampling techniques can be optimized compromizing between high resolution and large extent data collections. The coordinated distributed experiments and surveys based on these optimized sampling techniques might open new perspectives in comparative community ecology and macroecology. Materiai & Methods We used simulated data and field patterns recorded in form of spatial coordinates of plant individuals or presence of species in high resolution grids. Applying computerized resampling techniques we tested how coenostate variables will change by changing the sampling parameters (resolution, extent and the shape of sampled area). We used information theory models for analyses which represent complex community patterns (beta diversity of species combinations and species associations) as a function of spatial resolution. (Campetella et al. 2004). Main Results & Interpretations Results did not differ between high resolution grid data and spatial coordinate data. The absolute values of diversity and spatial dependence were similar between grids and transects, while the related characteristic scales slightly changed. Although scales were slightly biased when measured by transects, all ordering relations (i.e. differences between the compared vegetation types) remained invariant. Decreasing the spatial extent of samples resulted in strong increase of stochastic variance and produced artefacts. These problems were less pronounced when transects were used or the shape of grids become elongated. Comparing the effects of different sampling parameters, sample extent was the most critical. Using the same extent, transects give more representative data. Transect sampling was also much faster than other sampling methods. We concluded that resolution and extent could be optimized if long (50 m) transects of contagious 5 cm x 5 cm sampling units were used. This protocol was tested and proved to be applicable in a wide range of vegetation types including forest herb layer communities, grasslands in old fields, tall- and shortgrass steppes, mountain grasslands and semi-desert communities (Gosz et al. 2000, Virágh et al. 2008). We propose using this sampling design in future coordinated distributed experiments and surveys for studying non-equilibrium dynamics and assembly rules of vegetation in a more operative way and improving the predictability of vegetation processes