Plant species richness and composition in relation to landscape parameters in a traditional agricultural landscape of Goričko

V raziskavi obravnavamo spremembe v tradicionalni kulturni krajini SV Goričkega v zadnjih 230 letih ter vrstrno pestrost in floristično sestavo suhih in polsuhih polnaravnih travišč iz asociacij Hypochoerido-Festucetum rupicolae Steinbuch 1980 in Ranunculo bulbosi-Arrhenatheretum elatioris Ellmauer in Mucina s sod. 1993. Obravnavamo vrstno pestrost in floristično sestavo travišč v odnosu do izbranih krajinskih parametrov: površina fragmentov, oblika fragmentov (razmerje med obsegom in površino), raba tal (vzdrževana travišča in travišča v zaraščanju), naklon, ekspozicija, nadmorska višina, oddaljenost od naselij (hiš) in število različnih mejnih habitatnih tipov. Na območju raziskave smo locirali in floristično ovrednotili osemdeset polnaravnih, oligo- do mezotrofnih travišč. Travišča so predstavljala večji delež površine območja raziskave (61 %) ob koncu 18. stoletja. Do leta 2012 je bilo spremenjenih v druge kategorije rabe tal 50 % površine travišč s konca 18. stoletja. Glede floristične sestave in fiziognomije vegetacije smo fragmente suhih travišč razvrstili v štiri kategorije. Razlike v številu prisotnih vrst med obravnavanimi kategorijami suhih travišč so statistično značilne, enako velja za število habitatnih specialistov na fragmentih kot tudi za vrstno pestrost fragmentov, izraženo z vrednostmi indeksa Shannon-Weaver. Dokazali smo, da površina fragmentov ni v statistično značilni korelaciji s številom vrst na fragmentih (skupno število 180 vrst) pa tudi s številom tipičnih vrst (habitatni specialisti, skupno 45 vrst) ne. Vrstna pestrost (vrednosti indeksa Shannon-Weaver) fragmentov suhih travišč ni v statistično značilni zvezi s površino fragmentov, tudi z obliko fragmentov ne (razmerje med obsegom in površino). Današnje površine suhih travišč so le ostanki nekoč večjih površin, kar smo tudi dokazali s historičnim kartografskim materialom. Vrstno najbolj pesti so fragmenti v fazah zaraščanja in ne redno vzdrževani (košeni) fragmenti. Statistično značilna je korelacija med površino fragmentov in frekvenco pojavljanja štirih (od skupno 45) habitatnih specialistov suhih travišč. Specialiste srečamo predvsem na ohranjenih, manjših do srednje velike fragmentih s površino do 4147 m2. Dokazali smo, da se z večanjem pestrosti okolice (večanjem števila različnih mejnih habitatnih tipov) zmanjšuje vrstna pestrost vzdrževanih suhih travišč (redno košenih in motenih - ruderaliziranih) in povečuje vrstna pestrost travišč v fazah sukcesije (opuščena travišča). Zveza med nadmorsko višino in številom vrst na fragmentih suhih travišč je statistično značilna. Antropogeni dejavnik, ki pomembno vpliva na floristično sestavo fragmentov suhih travišč, je oddaljenost od naselij. Če upoštevamo le redno in občasno košena travišča, pa ta dejavnik poleg samega števila vrst statistično značilno pojasnjuje tudi število habitatnih specialistov na fragmentih suhih travišč. Analizirali smo pojavljanje (frekvenco in gostoto) navadne kukavice (Anacamptis morio) na fragmentih suhih travišč na območju raziskave. Skupno smo zabeležili 3812 primerkov omenjene vrste na traviščih z različno rabo tal. Ugotovili smo statistično značilno, pozitivno korelacijo med absolutno gostoto vrste Anacamptis morio in nadmorsko višino fragmentov suhih travišč ter statistično značilno, pozitivno korelacijo med maksimalno gostoto vrste ter nadmorsko višino fragmentov. Prav tako smo ugotovili tudi statistično značilno, negativno korelacijo med maksimalno gostoto vrste Anacamptis morio ter številom vrst na fragmentih suhih travišč. Dokazali smo statistično značilno, negativno korelacijo med maksimalno gostoto vrste ter vrstno pestrostjo fragmentov suhih travišč. Glavno gonilo, ki pojasnjuje današnje frekvence in gostote ter prostorsko razporeditev vrste Anacamptis morio na obravnavanem območju, je sedanja raba tal, režim upravljanja s suhimi travišči. Današnji obseg in vzorec prostorske razporeditve suhih travišč na območju raziskave predstavlja verjetno zadnji stadij ...We present the long term changes in the traditional agricultural landscape of NE Goričko Nature Park (NE Slovenia) and the species richness and composition of the remaining grassland fragments belonging to the associations Hypochoerido-Festucetum rupicolae Steinbuch 1980 and Ranunculo bulbosi-Arrhenatheretum elatioris Ellmauer and Mucina et al. 1993. Grasslands dominated in the landscape of the study area at the end of the 18th century. In 2012, 50% of the former grassland areas were lost and agricultural land dominated in the landscape. A systematic field survey of an area of 926 ha in the traditional Central-European agricultural landscape revealed 80 fragments of dry and semi dry, semi-natural grasslands. Plant species richness (number of species per grassland fragment) and diversity (measured as Shannon-Weaver diversity index) were studied in relation to selected landscape parameters: fragment area, fragment shape (perimeter/area ratio), land use treatment regime, number of different bordering habitat types, exposition, inclination, altitude and the distance to human settlements (houses). Based on species composition four groups of grassland were revealed: clustering was also explained with land use treatment. Fragment area and shape of the fragments did not affect the total number (180) of species per fragment significantlyneither did the number of habitat specialists (45) per fragment. The plant species diversity in the fragments was not found to be in significant relation with fragment area, neither with the shape of the fragments (perimeter/area ratios). However, the richest were those grassland fragments that had been abandoned and were in the early succession stage. Significant correlations between the fragment area and species frequency were found for four habitat specialists (out of 45 tested). They are found on smaller fragments with an area smaller than 4147 m2. We determined the increase in the total species number per grassland fragment along with increasing number of different bordering habitat types per fragment in case of abandoned fragments. In contrast to this is, on regularly mowed or ruderalized fragments, the relation just the opposite. We determined statistically significant, negative relation between the species richness (total number of species per fragment) of the analyzed grassland fragments and the altitude of the fragments. Anthropogenic factor that determines the total species number on the analyzed fragments is the distance to houses or infrastructure in general. If we consider the regularly mowed fragments only, the effect is evident also in relation to the number of habitat specialists per grassland fragment. The green winged orchid (Anacamptis morio) population was studied. We observed the number of specimens per grassland fragment and orchids density (number of specimens per m2) according to the land use treatment regime and the species diversity of the observed grassland fragments. In total, 3812 specimens of green winged orchid were detected. The density and the maximal density of the species are in a significant positive relation with the altitude of the analyzed grassland fragments. We report the significant negative relation between maximal density of the orchid and species richness of the analyzed grassland fragments, also significant negative relation between maximal density of the species and the total number of species per grassland fragment. The orchid prefers regularly mowed grasslands but is less frequent on grassland fragments with higher species diversity rates. Land use treatment regime of the dry grassland fragments (mowing and fertilization) and time since abandonment explain recent occurrence of Anacamptis morio, but also the altitude together with the distance to the human settlements. Past and present decision-making of local farmers, not the analyzed physical-geographic factors alone, generated the spatial pattern of distribution of dry grasslands in Goričko Nature..