Ilkka Hanski, who had been interested in butterflies already from a young age, chose the Glanville fritillary (Melitaea cinxia) as his research subject. In Finland, the species only occurs in the Åland Islands. This butterfly was found to live on the islands in a network of dry meadows whose size, shape, quality, and distance from one another varied from area to area. The Glanville fritillary proved to be a good choice for several reasons. The species is a relatively weak flier, which means that the Åland Islands function as a closed research laboratory, with no influx of migrants of the same species from outside. In addition, in Finland the butterfly has only one generation per year, which overwinters as groups of larvae in web-like winter nests that are fairly easy to spot in the field. In late summer, the caterpillars of the same brood build a nest either on ribwort plantain (Plantago lanceolata) or on spiked speedwell (Veronica spicata), which are the only plants in Finland that the species uses as food during the larval stage. By mapping the meadows where these host plants occur, it was also possible to identify the potential habitats of the Glanville fritillary.
The mapping of dry meadows containing the host plants of the Glanville fritillary was begun in the Åland Islands in 1991 by a small group of Ilkka Hanski’s doctoral students. The survey expanded into an island-wide project in 1993, from which point onward the fluctuations in the butterfly’s population size have been surveyed annually. Over time, the total number of mapped meadows has stabilized at around 4,000. The meadow network is not static: each year a small number of meadows disappear due to overgrowth or changes in land use. At the same time, even today some new meadows are still being formed.
The annual survey of the Glanville fritillary population size is conducted in early September. At that time, the winter nests are complete and are relatively easy to detect in the field. Since the beginning, the meadows occupied by the butterfly have also been visited the following spring, to estimate winter mortality of the nests. Since 2007, larval samples have also been collected in the Åland Islands, which provide further information on the effects of habitat structure and climate on the population genetics of the Glanville fritillary.
During the spring survey, data are also collected on the Cotesia parasitoid of the Glanville fritillary caterpillars, which may be found in certain areas of the Åland Islands. The Cotesia parasitoid parasitizes and kills the caterpillars. It occurs only in a few areas of Åland, but its effect on the butterfly’s population size may be locally significant. This parasitoid is easiest to detect in early spring, when its small, rice-grain-like cocoons can be found near the larval nests.
At the turn of the millennium, the then student Anna-Liisa Laine approached Ilkka Hanski with the idea that the network of ribwort plantain populations in the Åland Islands mapped by Hanski’s group would be well suited for studying the annual population dynamics of plant diseases. In 2001, Laine began her doctoral studies under Hanski’s supervision, and the survey of powdery mildew on ribwort plantain was initiated alongside the autumn survey of the Glanville fritillary. Laine defended her dissertation in 2005, but the disease community of ribwort plantain and the annual autumn survey of powdery mildew have remained an important part of her research to this day. The prevalence of the disease in populations has always been examined during the mildew surveys. In addition, during the years 2010–2016, samples were collected from infected populations for population genetic analyses and for gaining more detailed information on the epidemic.
In the summers 2012 – 2015, a separate ten-day survey was conducted on powdery mildew to determine its overwintering success. The study was conducted in July because the disease is visible by then but has not yet spread to new ribwort plantain populations. The mildew survives the winter in only some of the populations, and the distribution of the disease observed in autumn is explained partly by overwintering and partly by dispersal in late summer.
In the early years of the research, the target meadows in the Åland Islands were navigated to using paper maps with hand-drawn boundaries of the survey areas. All variables were recorded in the field on paper forms and later transferred to computers. In the early 2000s, handheld computers were introduced, allowing the annual data to be recorded directly in digital form. Since 2010, the EarthCape database (
Over the years, the data produced by the Åland surveying programme have been used in hundreds of scientific publications, Master’s theses, and doctoral dissertations. The collected data have been applied in mathematical modelling and have also served as inspiration for nature conservation projects and applications. Thus, the Glanville fritillary has become a globally known model species in metapopulation biology and it is being used as an example in biology teaching at universities around the world.
The autumn survey of powdery mildew in ribwort plantain populations has created the world’s largest long-term dataset on the occurrence of a plant disease in nature. The obtained information makes it possible to understand the interactions between diseases and their host organisms in changing environments.
The annual mapping of the meadows is possible only thanks to the many students who take part in the work. Therefore, for many students, the autumn surveys in the Åland Islands have been a part of their studies and one of their first experiences of practical research work.
Over the years, over 600 students and researchers have taken part in the Åland meadow monitoring.
Aapo Kahilainen, Aapo Salmela, Adrián Colino Barea, Aina Rossinyol Fernàndez, Aino Ahvo, Aino Hosia, Aino Tyyskä, Aki Aintila, Aki Saarela, Aki Suzuki, Aki-Tapio Saarela, Akseli Laukkanen, Aleksi Lehikoinen, Aleksi Mäntylä, Alex Pihl, Aliisa Harjuniemi, Aliisa Hartus, Alisa Roselius, Alma Oksanen, Amin Tarique, Ana Salgado, Anastasia Labudina, Andrea Maier, Anita Etholén, Ann-Marie Antaon, Ann-Sofie Åstrand, Anna Backholm, Anna Hahtola, Anna Haukka, Anna Hietala, Anna Isotalo, Anna Lehtonen, Anna Norberg, Anna Talvitie, Anna Toikkanen, Anna Välkki, Anna Weckman, Anna-Kaisa Kähkölä, Anna-Kristiina Hietala, Anna-Leena Mäkelä, Anna-Pauliina Iivonen, Anna-Riina Mustonen, Anne Halmepuro, Anne Hirvonen, Anne Holma, Anne Kiirikki, Anne Koivunen, Anne Luoma, Anne Lyytinen, Annemarie Hietala, Anni Arponen, Anni Honkanen, Anni Joensuu, Anni Nousiainen, Anni-Elina Aittamäki, Anni-Mari Pulkkinen, Anniina Mikkonen, Annika Kantokari, Annika Koskinen, Annika Vartio, Annina Rokka, Annu Tertsonen, Anou Londesborough, Anttu Lipponen, Anu Hjelt, Ari Turula, Arttu Soukainen, Atte Lahti, Audrey Bras, Auli Relve, Aura Raulo, Aurelia Ruohonen, Auri Koskenmäki, Belinda Mäki, Camilla Ilmoni, Carina Järvinen, Carly Lynsdale, Catherine Henricson, Christa Vilkki, Christina Church, Coong Lo, Eeva Huitu, Eeva Punju, Eeva Putro, Eeva Saarinen, Eeva Tiihonen, Eevi Rissanen, Eija-Leena Laiho, Eiko Höglund , Elena Rosa, Elias Liimatainen, Elina Bertell, Elina Karhu, Elina Karimaa, Elina Laurén, Elina Numminen, Elina Nystedt, Elina Pallaspuro, Elina Rautanen, Elina Siirilä, Elina Uotila, Elisa Metsovuori, Elisa Nygård, Elisa Päiviö, Ella Hemming, Ella Kaskikallio, Ella Lintunen, Elli Lappalainen, Elli Mattila, Ellinoora Leivo, Elsa Virolainen, Emma Hakanen, Emma Marjamäki, Emma Tolonen, Emmi Kytölä, Emmi Vähä, Erika Haakana, Essi Ahopelto, Essi Kaila, Eva Ehrnsten, Eva Jansson, Eveliina Stignell, Eveliina Kallioniemi, Eveliina Turpeinen, Eveliina Tuurnas, Frank Hering, Greta Kyrö, Guangchun Lei, Hanna Aho, Hanna Jauhiainen, Hanna Kauko, Hanna Koivula, Hanna Koskinen, Hanna Laakkonen, Hanna Parkkonen, Hanna Parri, Hanna Paulomäki, Hanna Seitapuro, Hanna Susi, Hanna Taavitsainen, Hanna Uusimaa, Hanna Wahlberg, Hanna-Leena Henttinen, Hanna-Leena Simola, Hanne Rajanen, Hanne Rapeli, Hanne Vihervaara, Hannele Penson, Hannele Pihlajamäki, Hasse Hyvärinen, Heidi Björklund, Heidi Blom, Heidi Hautala, Heidi Karbin, Heidi Kohtala, Heidi Viljanen, Heikki Ajosenpää, Heikki Koponen, Heikki Savolainen, Heikki Torkkeli, Heini Karvinen, Heini Lankia, Helena Antikainen, Helena Koivulehto, Helena Rosenlew, Heli Routti, Helmi Carlson, Helmi Nevalainen, Helmi Pett, Henna Makkonen, Henri Järvisalo, Henriikka Hallamaa, Henriikka Malkamäki, Henrik Talsi, Henrik Talsi, Hermanni Henriksson, Heta Rousi, Ida-Lotta Niinisaari, Iida Autio, Iina Ollikainen, Iiris Tattari, Ilari Falck, Ilik Saccheri, Ilkka Kivistö, Ilmari Kohonen, Ilona Merikanto, Ilona Oksanen, Ilona Peltoniemi, Ina Naukkarinen, Ina-Maria Naukkarinen, Inka Järvelä, Inkeri Sole, Irina Sytcheva, Jaakko Kuurne, Jaana Komonen-Kauramäki, Jaana Tervonen, Jan Salonen, Jan-Peter Bäckman, Janette Baarman, Jani Järvi, Janina Pykäri, Janna Hemming, Janna Uusitalo, Janne Granroth, Janne Hakanen, Janne Heliölä, Jari Ilmonen, Jari Julkunen, Jarno Tuimala, Jasmina Uusitalo, Jenni Hämäläinen, Jenni Jäänheimo, Jenni Korhonen, Jenni Lehtimäki, Jenni Leppänen, Jenni Punttila, Jere Salminen, Johan Ekroos, Johanna Ehrnsten, Johanna Eklund, Johanna Pelkonen, Johanna Vainikainen, Joni Uusitalo, Jonna Katajisto, Jonne Linna-Alho, Jouko Pokela, Juha Lumme, Juha Pöyry, Juha-Matti Pitkänen, Juhani Sirkiä, Jukka Alasaari, Jukka Hari, Jukka Ikonen, Jukka Rintala, Jukka T. Lehtonen, Julia Kilpiniemi, Julia Palorinne, Julian Schach, Jussi Ikävalko, Jussi Mäkinen, Jussi Nygren, Juulia Lehtinen, Juuso Björkroth, Jyrki Holopainen, Kaisa Kantanen, Kaisa Kontas, Kaisa Luodekari, Kaisa Rämö, Kaisa Torppa, Kaisa Torri, Kaisu Mankinen, Kalevi Trontti, Kalle Huttunen, Kalle Kröger, Kalle Meller, Kalle Saramo, Karin Niemi, Karolina Stenfors, Kasimir Tulenmaa, Kata-Riina Valosaari, Katarina Meramo, Kati Yläranta, Katja Bargum, Katja Bonnevier, Katja Enberg, Katja Fedrowitz, Katja Ojala, Katja Rönkä, Katri Korpela, Katri Luukkonen, Kiira Nordqvist, Kim Jaatinen, Kirsi Järvinen, Kirsi Reponen, Krista Raveala, Krista Viren, Kristian Lindqvist, Kristiina Hildén, Kristiina Visakorpi, Kristjan Niitepõld, Kukka Kyrö, Lasse Lindqvist, Laura Hiisivuori, Laura Jäättelä, Laura Kares, Laura Mattila, Laura Nummelin, Laura Nurmi, Laura Soininen, Lauri Ahlberg, Lauri Kajander, Lauri Partanen, Lauri Rosenius, Lauri Sillantie, Lauri Tuomiranta, Lea Ala-Ilomäki, Lea Fewer, Lea Heikkinen, Leea Ojala, Leena Jyrinki, Leena Laitala, Leevi Korpikoski, Lehtinen Oskari, Leila Kovasin, Leila Uusirantanen, Lena Huovinen, Liisa Maanavilja, Liisi Matilainen, Lina Munsterhjelm, Linda Knapp, Linda Peltola, Linda Rosqvist, Linda Uusihakala, Lindholm Tanja, Lola Fernández Multigner, Luisa Woestmann, Maarit Nurminen, Maija Ihantola, Maiju Lanki, Malin Aulanko, Malin Ek, Malla Kirjokangas, Mar Cabeza-Jaimejuan, Mari Kekkonen, Mari Koskela, Mari Paakkinen, Mari Pihlajaniemi, Maria Degerlund, Maria Hällfors, Maria Reiman, Maria Tuomi, Marianne Kovasin, Marika Aihio, Marika Tikka, Marja Kosme, Marjo Kuronen, Marjo Mansikkamäki, Marjo Saastamoinen, Mark Camara, Markku Lahtinen, Markku Ojanen, Marko Nieminen, Marko Pesu, Markus Hiukka, Markus Haveri, Markus Lauha, Markus Seppälä, Markus Tietäväinen, Martti Rajamäki, Martti Ylätupa, Mats Ittonen, Matti Koivula, Matti Puljujärvi, Mebin George Vargehse, Meena Lindroos, Meeri Mäki, Meri Ensiö, Mervi Laitinen, Mia Kraft, Mia Vaittinen, Miina Fagerlund, Miisa Virta, Mika Kalliovirta, Mika Saarenpää, Mika Siljander, Mikko Heini, Mikko Immonen, Mikko Jalo, Mikko Kivikoski, Mikko Kolkkala, Mikko Kuussaari, Mikko Pelto-Arvo, Mikko Putkonen, Mikko Sonninen, Mikko Tiira, Mikko Tiusanen, Milja Aitolehti, Milla Kallio, Milla Vahtila, Minea Andersson, Minna Brunfeldt, Minna Kohonen, Minna Lyytikäinen, Minna Pekkonen, Minttu Hannonen, Mira Korpi, Mirjami Smalén, Nadja Verspagen, Netta Lempiäinen, Niclas Fritzén, Nietos Hietanen, Niklas Kumlin, Niklas Wahlberg, Niko Björkell, Niko Felt, Nina Hyvärinen, Nina Rautjärvi, Nina Siitonen, Ninni Mikkonen, Noora Hildén, Noora Parkkonen, Nora Arnkil, Nora Bergman, Norio Hirai, Nuutti Kangas, Olli Lilja, Olli Ojala, Onerva Aula, Onni Purhonen, Oona Uhlgren, Otso Häärä, Outi Lerssi, Outi Pihlajamäki, Outi Pulliainen, Outi Viinikka, Paavo Hellstedt, Panu Hälvä, Pasi Ala-Opas, Pasi Partanen, Patrik Karell, Paula Peitola, Paula Rantanen, Paula Salonen, Paula Uotila, Pauliina Hyttinen, Peetri Pihko, Pekka Saarinen, Peter Kullberg, Petra Lattunen, Petteri Mönkkönen, Pezhman Safdari, Pia Välitalo, Pilvi Eronen, Pirta Palola, Rebecca Nygrén, Rebekka Kukowski, Reena Karvonen, Reetta Hallikainen, Reetta Ljungberg, Riikka Kaartinen, Riina Myllymäki, Riitta Nironen, Riitta Ovaska, Riitta Toivonen, Riku Kangasniemi, Rosemary Setchfield, Saana Kemppi, Saana Keskinen, Saana Liimatainen, Saana Railo, Saara Hartikainen, Saara Jussila, Saara Karjalainen, Saara Kilpinen, Saara Tähtinen, Saara Vauramo, Saija Papunen, Saila Kuokkanen, Sakari Nousiainen, Salla Heiman, Salla Rantala, Salla Sacklen, Salla Suomensaari, Salla-Maarit Härkönen, Sami Lindgren, Sami Ojanen, Sampsa Vilhunen, Samu Piha, Sanja Hakala, Sanna Eronen, Sanna Kokkonen, Sanna Korhonen, Sanna Korkonen, Sanna Leppänen, Sanna Mäkeläinen, Sanna Pekuri, Sanna Saarinen, Sanna Suikkanen, Sanna-Riikka Remes, Sanni Kouhia, Sanni Monto, Sanni Turunen, Santtu Nissilä, Sara Neggazi, Sara Ollila, Sari Haikola, Sari Suhonen, Saskya van Nouhuys, Satu Laitinen, Satu Viitasalo, Senja Piiroinen, Shridhar Halali, Siina Lönni, Siiri Fuchs, Siiri-Anna Fuchs, Silja Kiuru, Silva Lehtonen, Sini Mursinoff, Sini Penttilä, Sini Salko, Sini Wallin, Sirke Piirainen, Sofia Gripenberg, Sofia Virtanen, Soili Huttunen, Sonja Blom, Sonja Kirla, Steve Matter, Susanna Airaksinen, Susanna Halttunen, Susanna Heiman, Susanna Kukkola , Susanna Rokkanen, Susanna Tarkiainen, Susu Rytteri, Suvi Hakulinen, Suvi Ikonen, Suvi Sallinen, Tapio Gustafsson, Tarja Kainlauri, Taru Tornikoski, Terhi Hilli, Terhi Lahtinen, Terhimarja Malkavaara, Tero Kirjosalo, Tero Lukkari, Tiia Reinikainen, Tiina Aalto, Tiina Laakkonen, Tiina Pasanen, Tiina Riikonen, Tiina Salminen, Timo Pakkala, Timo Pihlajamäki, Timo Tuuri, Timothee Poupart, Tinja Hyvönen, Tinto Aaltonen, Tobias Tamelander, Toby Fountain, Tom Tamlander, Tommi Tolvanen, Toni Cases, Tonje Lindeman, Topi Lehtonen, Torsti Schulz, Tove Panelius, Tuomas Kankaanpää, Tuomas Uola, Tuomo Pihlaja, Tuukka Virtanen, Tuulikki Seppälä, Tuure Houni, Ulla Riihimäki, Ulla Tuomainen, Ulpu Rista, Unni Pulliainen, Usko Szeto, Valeria Valanne, Varpu Pärssinen, Vaula Lukkarinen, Veera Kuparinen, Veera Lyytikäinen, Veera Salminen, Veera Tuovinen, Veli-Pekka Antti-Poika, Venla Kontiokari, Venla Lindell, Venla Luttinen, Veronika Westergård, Vesa Hyyryläinen, Vesa Selonen, Viia Forsblom, Viivi Lidholm, Ville Junttila, Ville Vepsäläinen, Vilma Metsärinne, Vilma Palomäki, Vilma Rajasuu, Vilppu Välimäki, Virpi Immonen, Virpi Karén, Virpi Lintunen, Virve Koivuranta, Wee Tek Tay, Xinyue Muurimäki, Yunus Vilkkavaara Cankocak, Zdravko Kolev, Zeren Gürkan