Populaciona ekologija močvarskog mravnika [Phengaris teleius (Bergsträsser, 1779)] u Srbiji

Abstract

Ekologija je prešla dugačak razvojni put, od primene u različitim granama privrede, do proučavanja sveukupnih odnosa u živom svetu. Korišćenje ekoloških, biogeografskih, genetičkih, taksonomskih i evoluciono-bioloških znanja u rešavanju problema izumiranja savremenih vrsta dovelo je, pre pedesetak godina, do formiranja zasebne biološke discipline nazvane konzervaciona biologija. Uz razvoj konzervacione biologije razvijalo se i shvatanje o potrebi za zaštitom insekata, a prva zapažanja i studije zasnovani su upravo na proučavanju dnevnih leptira. Umesto izlovljavanja, ubrzo je kao glavni faktor njihovog ugrožavanja istaknut loš kvalitet staništa. Dokazano je da i male promene u kvalitetu staništa ili mikroklimi mogu imati poguban efekat na preživljavanje populacija leptira. Drugo značajno zapažanje bilo je da održavanje staništa od strane ljudi može da koristi ovim insektima. Danas se brojne aktivnosti sprovode u cilju zaštite dnevnih leptira, od uključivanja stotine hiljada volontera u programe monitoringa, preko redovnih procena ugroženosti taksona, donošenja zakonskih regulativa, do izrade konkretnih planova za pravilno održavanje staništa. Važnost leptira mravnika (rod Phengaris) se posebno ističe kada se uporede sa ostalim zaštićenim i ugroženim vrstama u Evropi. Do pre 20 godina neobjašnjiva izumiranja, kompleksan životni ciklus (koji uključuje i razvoj gusenica unutar mravinjaka), status ugroženosti i atraktivan izgled leptira podstakli su brojna istraživanja. Ostvareni rezultati se sada koriste za pravilno gazdovanje staništima i zaštitu mravnika širom Evrope. Poznati areal močvarnog mravnika (vrsta Phengaris teleius) obuhvata umereni deo Evrope i Azije (od zapadne Nemačke do Japana) i uključuje nekoliko država koje se graniče sa Srbijom: Rumuniju, Mađarsku i Hrvatsku. U Srbiji je ovaj leptir zabeležen tek 2012. godine na krajnjem severu države, nakon čega se javila potreba za detaljnom studijom, kojom bi se dobio uvid u stanje populacija i status ugroženosti leptira. Stoga ova disertacija ima cilj da 1) utvrdi rasprostranjenost močvarnog mravnika i kvalitet njegovih staništa u Srbiji i da 2) sagleda populacionu dinamiku vrste uz uporedni prikaz dobijenih rezultata na lokalitetima u Srbiji i na ostalim lokalitetima u Evropi. To bi pomoglo da se precizno odredi konzervacioni status, postavi osnova za monitoring i predlože adekvatne mere za dugoročno očuvanje močvarnog mravnika u Srbiji, ali i u Evropi. Kako bi ostvarili navedene ciljeve, staništa močvarnog mravnika u široj okolini Subotice su kartirana i predstavljena u vidu mape upotrebom GIS alata. Ukupno analizirana površina od 2,27 km2 obuhvatila je sledeća zaštićena prirodna područja: Park izuzetnih odlika „Subotička peščara“, Specijalni rezervat prirode „Ludaško jezero“ i Specijalni rezervat prirode „Selevenjske pustare“. Uticaj različitih parametara staništa na prisustvo leptira je sagledan pomoću univarijantne statističke analize i generalizovanih linearnih modela. Uvid u populacionu ekologiju vrste je dobijen upotrebom podataka iz studija markiranja i ponovnog ulova (od 2012. do 2014. godine), koji su analizirani u programu MARK. Georeferencirani podaci o markiranim leptirima su korišćeni u za analizu pokretljivosti jedinki (premeštanje i disperzija) u programu R. Tokom ovog istraživanja, močvarni mravnik je zabeležen unutar šest novih MGRS kvadrata veličine 10×10 km, na području severne Srbije i južne Mađarske. Od analiziranih 97 livada sa biljkom hraniteljkom (Sanguisorba officinalis), leptir je pronađen na 62 i to skoro uvek u zaštićenim područjima. Sva pronađena staništa se redovno kose, a veličina i brojnost biljke hraniteljke imaju najveći uticaj na prisustvo i brojnost leptira. Tokom studije markiranja i ponovnog ulova leptiri su prelazili mala rastojanja između dva uzastopna hvatanja unutar svojih livada (oko 40 metara), pri čemu su ženke bile mobilnije. Zabeležene su i znatno duže migracije između livada (do 1,9 kilometara), a procenjeno je da tokom jedne godine šest jedinki može da pređe rastojanje od pet kilometra. Ukupna veličina svih populacija močvarnog mravnika u Srbiji je procenjena na 15.000 jedinki. Gustina lokalnih populacija leptira se kretala od 82 do 419 jedinki po hektaru, pri čemu su najgušće lokalne populacije zabeležene u Selevenju i u okolini Ludaškog jezera, dok je najmanje jedinki po hektaru staništa bilo u Subotičkoj peščari. Dužina života se kretala od 2,3 do 4,5 dana i bila je kraća na staništima koja su gusto naseljena leptirima. Odnos polova je bio blizu uravnoteženom odnosu mužjaka i ženki (1:1). Populacije močvarnog mravnika koje su pronađene ovim istraživanjem u Srbiji i Mađarskoj proširile su poznato rasprostranjenje vrste za oko 40 kilometara. Za opstanak biljke hraniteljke, mrava domaćina, a posledično i močvarnog mravnika, bile su zaslužne mere očuvanja preostalih fragmenata poluprirodnih staništa unutar zaštićenih prirodnih dobara. Iz prikupljenih podataka o razmenama jedinki, pretpostavili smo postojanje jedne velike populacione strukture u istraženoj oblasti. Broj jedinki unutar ove populacije bi bio među najvećim poznatim u Evropi. Velika brojnost jedinki i relativna stabilnost izračunatih parametara nije očekivana za populacije na rubu areala i verovatno se može objasniti biološkim interakcijama. Korelacija između dužine života i gustine jedinki unutar populacije predstavlja potvrdu poznatog ekološkog zakona regulacije brojnosti populacije u zavisnosti od gustine. Zanimljivo je istaći životni vek močvarnog mravnika u Subotičkoj peščari od blizu 4,5 dana u proseku (najviše 18 dana), koji je do sada najduži zabeleženi na svetu. Pored toga, period aktivnosti ovih leptira u Srbiji je različit u odnosu na sve poznate populacije i pomeren je za oko 15 dana kasnije u toku sezone (od druge polovine jula do septembra). Podaci dobijeni ovom studijom uvrstili su močvarnog mravnika među ugrožene taksone na nacionalnom nivou (EN). Zbog toga postoji potreba da se obezbedi njegova zakonska zaštita, osigura dugoročan monitoring preostalih populacija i osmisle konzervacione mere za njegovo očuvanje. Ove mere treba zasnivati na dobroj praksi, koja se već sprovodi na području zaštićenih dobara. To obuhvata aktivnosti kao što su: mozaično i neistovremeno košenje bliskih parcela, ostavljanje nekošenih delova livada, izdavanje delova parcela koje su u državnom vlasništvu većem broju zemljoradnika, sprečavanje ukrupnjavanja parcela i intenzifikacije poljoprivrede. Osnovno je da košenje treba vršiti van perioda aktivnosti odraslih leptira i njihovih mladih gusenica, što obuhvata vreme pre početka jula i nakon polovine septembra. Pored toga, značajno bi bilo prikupiti još podataka o mikroklimatskim parametrima, vegetaciji, mravima domaćinima, obezbediti očuvanje velikih i zdravih populacija močvarnog mravnika, raditi na povezivanju izolovanih staništa močvarnog mravnika i pratiti rekolonizacije njegovih potencijalnih staništa koja još uvek nisu naseljena. Nadam se da će podaci izneti u okviru ove disertacije podstaći detaljne ekološke studije na dnevnim leptirima u Srbiji i pomoći zaštiti močvarnog mravnika i drugih vrsta.

Ecological research has come a long way from the first applications in different branches of economy to the comprehensive studies on wildlife interactions. Using the knowledge from ecology, biogeography, genetics, taxonomy and evolutionary biology to solve problems of extinction of contemporary species resulted, about fifty years ago, in the rise of a new biological discipline named conservation biology. The need to conserve insects was increasing together with the development of conservation biology, and the first conservation oriented studies were those on butterflies. Soon, the low quality of habitats instead of butterfly over-collecting was recognised as the main threat factor. It has bean proven that even the small changes in microclimate or the habitat quality could have fatal effects on the survival of butterfly populations. Another observation suggested that habitats sustained by humans could also bring benefits to these insects. Today, numerous activities are implemented in order to conserve butterflies and moths and some measures include involving hundreds of thousands volunteers in monitoring programs, regular assessing of species threat status, voting for new legislation and developing specific plans for sustaining the appropriate habitat conditions. The Large Blue butterflies (genus Phengaris) are of special value when compared to other protected and endangered species in Europe. Until 20 years ago unexplained extinctions, complex life cycle (which includes development of caterpillars inside the ant nests), high threatening status and attractive appearance encouraged numerous studies on these butterflies. Achieved results are now being used for correct management of habitats and protection of the Large Blues across Europe. Known areal of the Scarce Large Blue (species Phengaris teleius) includes temperate parts of Europe and Asia (from western Germany to Japan) and is recorded in several countries bordering Serbia: Romania, Hungary and Croatia. This species was recorded only in the far North of Serbia in 2012, when the urgent need for detailed studies aiming to collect data on the condition and the threat status of its populations was recognised. Therefore, this thesis aims to 1) acquire the Scarce Large Blue distribution data and habitat quality parameters from Serbia and to 2) give an overview on its population dynamics with a comparison of obtained results from different localities in Serbia and among other localities in Europe. It could help to precisely define species conservation status, set the basis for regular monitoring and suggest proper measures for long term conservation of the Scarce Large Blue in Serbia, but also in Europe. In order to achieve the mentioned aims, habitats of the Scarce Large Blue in the wider area of Subotica were mapped in the field and shown on a map using GIS tools. Total analysed area of 2,27 km2 included the following protected areas: Landscapes of exceptional features “Subotička peščara”, Special nature reserve “Ludaš lake” and Special nature reserve “Selevenjske pustare”. The effect of habitat characteristics on butterfly presence was evaluated using univariate statistical methods and generalised linear models. The insight into population ecology of the species was enabled using the data from the mark-release-recapture studies (in the period 2012-2014), that were analysed in MARK software. Georeferenced data about marked individuals were used for the analysis of their movements (displacement and dispersal) in R software. During this research, the Scarce Large Blue was recorded inside of six new MGRS squares of 10×10 km, in the area of northern Serbia and southern Hungary. From 97 analysed meadows containing butterfly host plant (Sanguisorba officinalis), the butterfly was found on 62, almost always inside the protected areas. All the habitats have been regularly mown and the size and number of the host plants seemed to have a crucial effect on the presence and the number of butterflies. During the mark-release-recapture study the butterflies travelled short displacement distances between subsequent captures (about 40 meters), with females being more mobile sex. Dispersal distances between habitat patches were longer (up to 1.9 kilometres) and it was estimated that six individuals per year could travel up to the distance of five kilometres. The size of all Scarce Large Blue populations in Serbia was estimated to 15,000 individuals. Density of butterfly populations ranged from 82 to 419 individuals per hectare, with the most densely populations being located in Selevenj and the vicinity of Ludaš Lake, and the least densely populations in Subotica Sands. The life span was between 2.3 and 4.5 days and was shorter in habitats that were densely populated by butterflies. The sex ratio was close to a balanced ratio of males and females (1:1). New populations of the Scarce Large Blue in Serbia and Hungary expanded the known range of the species about 40 kilometres. Measures for conserving the remaining semi-natural habitat fragments inside protected areas were crucial for preserving the host plant, the host ants and consequentially the Scarce Large Blue. From the collected data on the exchange of individuals, we assumed an existence of one large population structure in the studied area. The number of individuals inside of this population is among the highest known for Europe. Large number of individuals and a relative stability of the estimated parameters were not expected for populations at the edge of the species range, and could be explained by biological interactions. The negative correlation between the life span and the density of individuals represents a confirmation of the well known ecological rule about density dependant regulation of populations. It is interesting to note that the life span of the Scarce Large Blue reaching 4.5 days on average (maximum 18 days) in Subotica Sands is the longest recorded so far. Besides this, the period of activity for these butterflies in Serbia differs from all other known populations in Europe and is shifted some 15 days later in the season (from second half of July to September). The data gathered in this study placed the Scarce Large Blue among endangered taxa on the national level (EN). For this reason, there is a need to acquire its legal protection, ensure long term monitoring of the remaining populations and develop conservation measures for its preservation. Measures should be based on the good practice that was already conducted in the protected areas. This includes activities such as: mosaic and time-independent mowing of the neighbouring plots, leaving unmown parts of the meadows, laying out state owned land to as many farmers possible, preventing land plots to be enlarged and agriculture to be intensified. Crucially, mowing should not be conducted during the activity of adult butterflies and young caterpillars, which includes the period from beginning of July to the middle of September. Also, it would be important to gather more data about the microclimatic parameters, the vegetation and the host ants, ensure the preservation of large and healthy populations of the Scarce Large Blue, work on the connection of its isolated habitats and track the recolonisation of potentially suitable habitat patches that were not inhabited by the butterflies. I hope that the data presented in this thesis will initiate more detailed studies on population ecology of the butterflies in Serbia and help to protect the Scarce Large Blue and other species.