Florális diverzitás mintázatok: egy komparativ funkcionális megközelités = Fine-scale neighborhoods in plant communities: a comparative functional approach

Munkánk alapgondolata, hogy a növényfajok együttélésének értelmezéséhez a térbeli függőség mellett a fajok találkozási valószínűségeit leíró finom térléptékű diverzitási relációk ismerete is szükséges. Standard mintavételi módszereket fejlesztettük és számos hazai gyeptársulásban végeztünk összehasonlító mikrocönológiai vizsgálatot. Null-modellekkel kimutattuk, hogy a fajok találkozási valószínűségei az átlagtér közelítéssel becsült értéktől az egyensúlytól távoli társulásokban térnek el jobban. A diverzitásmintázatok funkcionális értelmezéséhez növényi tulajdonságokat használtunk, amelyek egy részét terepen mértük. Leírtuk ezek szukcessziós trendjeit és segítségükkel társulási szabályokat állapítottunk meg. A florális diverzitást, mint a béta diverzitás egy új mérőszámát értelmeztük és leírtuk a homoki gyepek klímaváltozás hatására várható differenciálódási trendjét. Löszgyepek és homoki gyepek összehasonlító elemzésével kimutattuk, hogy a diverzebb állományok rezíliensebbek és a florális diverzitás időbeli fluktuációja az átlagos florális diverzitással forditottan arányos. Terepi és szimulációs vizsgálatok összekapcsolásával bizonyítottuk, hogy a domináns faj az egymáshoz hasonló szubordinált fajokat térben elszigetelheti és ezzel hozzájárul a közösség diverzitásának a fennmaradásához. Eredményeink szerint a gyepállományon belüli szerkezeti komplexitást a domináns, ill. a gyakori fajok alakítják ki, míg a többiek ehhez az alapszerkezethez asszociálódnak. | Plant neighborhood diversity (PnD) relationships provide important complementary information for assembly rules. Fine-scale diversity patterns and assembly rules were assessed in various Hungarian grasslands using a standard sampling protocol. Null-models showed that deviance from the mean field approximation was stronger in non-equilibrium communities. Several plant traits were measured in the field and used for interpreting community structure. The relative importance of different plant traits were estimated in contrasting grassland habitats and in different stages of forest succession. Expected differentiation of sand grasslands due to climate changes were described by a new PnD based beta diversity index. By analyzing long-term data sets, the average PnD we found to be in inverse ratio to the CV% of PnD. We used spatially explicit individual based simulation models for demonstrating that similar subordinate species can coexist within the matrix of dominant species under specific conditions. Using information theory models for analyzing fine-scale patterns in various grasslands we showed that fine-scale structural complexity was created mainly by the dominant species and subordinates were associated to this matrix structure

High resolution vegetation assessment with beta-diversity - a moving window approach

Monitoring designs are often suffering from the inherent non-stationarity of the monitored systems. To overcome this limition, we propose a sampling designs based on high resolution mapping and spatial analyses with double spatial scaling process. Applying for vegetation, we record the presence of plant species along 26 m or 52 m long belt transects of 520 (or 1040) units of 0.5 cm x 0.5 cm contiguous microquadrats. Beta diversity (represented as the diversity of species combinations) is estimated by subsequent computerised samplings from the baseline transect data sets. Beta diversity is scaled with changing resolutions across a range of scales from 5 cm x 5 cm to 5 cm x 500 cm. Second, it is also scaled using moving window. Local maximum of beta diversity is repeatedly calculated in 5 m extent observational windows shifted along the transect with 1 m lag, and the spatial variability of vegetation is visualized by the related beta-diversity profile. Using field example, we demonstrate that beta diversity, when applied with our methodology, is a sensitive indicator, and it can reveal more information than alpha or gamma diversity.</jats:p

Fűvetés hatása a parlagfű (Ambrosia artemisiifolia L.) tömegességére egy tiszaalpári fiatal parlagon

A felhagyott szántóföldek regenerációjának elősegítésére egyre növekvő területen alkalmaznak valamilyen gyeprekonstrukciós technikát. Ez gyakran alacsony diverzitású fűmagkeverék vetését jelenti. A vetett füvek között általában kompetitív fajok is vannak, ezek vetése hatékony eszköz lehet a gyomnövények megfékezésére. Vizsgálatainkat egy Tiszaalpárhoz közeli fiatal parlagon végeztük, melyet másodlagos szikes rétek illetve homoki- és lösz- sztyeprétek vesznek körül. A kísérlet során veresnadrág-csenkesz (Festuca pseudovina Hack.), - mely az adott társulásban természetes társulásalkotó lehet - és társulásidegen angolperje (Lolium perenne L.) magokat vetettünk. Megvizsgáltuk, hogy a fűvetés milyen hatással van a szántók felhagyását követően gyakran nagy tömegben megjelenő parlagfű borítására, és összehasonlítottuk a különböző vetések diverzitását. Az eredmények szerint a fűvetés az első két évben visszaszorította parlagfüvet, az angolperje jobban, mint a veresnadrág-csenkesz. Három év után a parlagfű borítása a teljes területen elenyésző volt. A csenkeszes-vetés diverzitása magasabb volt, és szerkezete nem volt erősen hierarchikus, mint az angolperjés kezelésé. Ezért restaurációs célokra inkább a természetes társulásalkotó faj vetését javasoljuk a hagyományos extenzív művelési módok fenntartása mellett

The impact of the lesser blind mole rat [Nannospalax (superspecies leucodon)] on the species composition and diversity of a loess steppe in Hungary

Our aim was to investigate the species richness and diversity of a loess grassland influenced by the digging of the lesser blind mole rat [Nannospalax (superspecies leucodon)] and to study the effect of this disturbance to diversity. The study was conducted in the Külső-gulya loess grassland (Körös-Maros National Park), which is unique in Hungary due to its excellent soil quality and the large spatial extent of natural loess meadow steppe. We recorded the cover of species in 50x50 cm plots. Altogether 12 plots were sampled on mounds of mole rat and 12 plots as a control in the area with no mounds. Differences in species richness, Shannondiversity, evenness and total cover between disturbed and control plots were tested by One-Way ANOVA. There were no significant difference neither in the number of species, nor in the Shannondiversity and evenness. There were differences in the species composition detected by PCO ordination. We can conclude that the presence and disturbance of the mole rat influence the composition of the grassland significantly but it does not cause a difference in the species richness, diversity and total cover. Our results suggest that this grassland has adapted to these natural disturbances

Meta-analysis of field scale spatial variability of grassland soil CO2_{2} efflux: Interaction of biotic and abiotic drivers

In this study eight temperate grassland sites were monitored for soil CO2 efflux (Rs) and the spatial covariate soilwater content (SWC) and soil temperature (Ts) at fine scale in over 77 measurement campaigns. The goals of thismultisite study were to explore the correlations between environmental gradients and spatial patterns of Rs, SWCand Ts, which are not site-specific and to quantify the relevance of biotic and abiotic controls over spatial patternsalong increasing vegetation structural complexity. These patterns in water-limited ecosystems in East-CentralEurope are likely to be influenced by summer droughts caused by the changing climate.A consistent experimental setupwas applied at the study sites including 75 sampling locations along 15m circulartransects. Spatial data processing was mainly based on variography. Two proxy variables were introduced torelate the site characteristics in terms of soils, water status and vegetation. Normalised SWC (SWCn) reconciledsite-specific soil water regimes while normalised day of year integrated temperature and vegetation phenology.A principal component analysis revealed that the progressing closure of vegetation in combination with large Rsand SWCn values, as well as low Ts and Rs variability support the detectability of spatial patterns found in both theabiotic and biotic variables. Our results showed that apart from SWC the pattern of soil temperature also had aneffect on spatial structures.We detected that when the spatially structured variability of Ts was low, a strong negativecorrelation existed between SWCn and the spatial autocorrelation length of Rs with r = 0.66 (p b 0.001).However, for high spatially structured variability of Ts, occurring presumably at low Ts in spring and autumn,the correlation did not exist and itwas difficult to quantify the spatial autocorrelation of Rs. Our results are indicativeof a potential shift from homogeneity and dominance of biotic processes to an increased heterogeneity andabiotic regulation in drought prone ecosystems under conditions of decreasing soil moisture

Trait-based assembly rules across climatic gradients of European grasslands are affected little by extreme drought

Changes in climate such as extreme drought events might interfere with grassland ecosystem processes. European grasslands support a rich flora with high small-scale species density, mirroring complex mechanisms of coexistence in different habitat templates. Do these mechanisms differ in relation to climate, soil and land use history? Are they affected by extreme drought? We investigated fine-scale patterns of trait-based community assembly in European grasslands across continental and experimental climatic gradients within the framework of the BiodivERsA project SIGNAL. The gradient extends from mesic (FR, GE) to intermediate (IT, BG) and to xeric grasslands (TR, HU). The sites also differ in management, disturbance history, geology and edaphic factors and represent common grassland-types of the respective country. We sampled fine-scale patterns of species combinations (rooting individuals) in six 1.20 m X 0.40 m blocks, subdivided into micro-quadrats of 100 cm2, for each treatment (control, drought) at each site in two years (2013, 2014). Based on the key plant-traits specific leaf area (SLA), height and seed mass we calculated Rao’s functional diversity (FD) and further diversity indices for each micro-quadrat and compared them to a null model using the randomization method of Schamp et al. (2008; Journal of Ecology 96: 204–212); deviation of FD from random expectation was interpreted as trait divergence or convergence. Strong seed-mass divergence in the dry Turkish grassland pointed towards complex disturbance history, while the other countries showed convergence. Plant-height convergence most likely indicated the importance to have similar best traits in productive grasslands (FR, GE) or trait-similarity due to environmental filters (HU, IT) as does the strong SLA-convergence in Italy. We conclude that assembly rules can be contrasting and context dependent at different grassland sites and climatic differences are often masked by local factors such as disturbance regime or soil heterogeneity. Experimental extreme drought led to a tendency towards trait-convergence in seed mass in Italy probably constraining the regeneration niche. The tendency of SLA-divergence in France could indicate a tempering of competitive situations. Apart from that, assembly rules were remarkably stable under drought as we found neither significant changes in trait divergence or convergence nor switches between them across countries