Réunion, the island of volcanos

We visited Réunion island during and after the Island Biology Conference, here comes our trip report.

Réunion is a member of the Mascarene islands, together with Mauritius and Rodrigues. The island is situated in the Indian Ocean, 800 km east from Madagascar and slightly north to the Tropic of Capricorn. According to the estimations the volcanic island is 2-3 million-year-old, so it is a relatively young one. Its area is only 2511 km2 but it has a very diverse relief and climate. Climatologists distinguish approximately 200 types of microclimates on Réunion! The western coast is the leeward coast with a milder climate, while the eastern, windward coast and the central mountain regions receive far more precipitation. A yearly rainfall of 6,000-12,000 mm is typical, and there were some years with 18,000 mm of total precipitation. The Guinness Record of the maximum amount of precipitation within 24 hours was registered in Cilaos, Réunion: the record is 1,870 mm!!!  (This amount of rain falls within three years in Hungary.) In July, there is the mild Austral winter with 20-27 C temperatures and not so much rain, so it is a perfect destination for those who want to escape from the hot European summer.

The location of Réunion in the Indian-ocean.

The first permanent settlers of the island arrived from Madagascar in the early 1500s. The first Europeans were the Portuguese who arrived in 1507. The French started to rule the island from the early 1600s. Colonisation was intensified from 1665, when the French East India Company sent settlers to Réunion. The wealth and economical development of the island was mainly due to two flagship products: the Bourbon vanilla and the sugar cane. Today, Réunion is an overseas department of France. For a European traveler it is very casual: the currency is Euro, the whole island is absolutely safe and can be best explored by car.

The Bourbon vanilla is one of the flagship delicacy products of the island. Vanilla is an orchid species native in Mexico, which was introduced to Réunion in the 19th century. First, its cultivation was very challenging, as there were no proper pollinators in the island. The invention of Edmond Albius, a 12-year-old slave was the solution to the problem: he figured out how to pollinate vanilla by hand. This invention gave the wealth for the French Bourbon vanilla barons. The name Bourbon is included in the scientific name of many endemic plant and animal species, in the form of 'borbonicus'. Nowadays there is a trend for growing vanilla inside the rainforests - this is a very good initiative as this way the forest habitats can be maintained.

The other world-class product of the island is the sugarcane, and the famous rum made of it. Unfortunately sugar cane plantations occupy large areas in the lowlands and mid-elevated places; thus, many of the original habitats disappeared there. However, there are still more natural habitats here than in Mauritius.

The local pineapple is great - it is very sweet and soft.

Saint Pierre has one of the oldest harbour in the island. This small city has a great atmosphere, full with life.

The island has multicultural influences which can be sensed also in its great cuisine: Creol, French, Asian and African flavours inspire the great dishes. Streetfood is really delicious, here you can see a large selection of samosas.

Réunion has two major volcanic massifs: the extinct volcano, Piton de Neiges and the active volcano, Piton de Fournaise. The last eruption of Piton de Neiges ('Snowy Peak') occurred approximately 10,000 years ago; today, this is the highest peak on the island and also on the Indian Ocean, with its height of 3071 m. Very rarely it occurs that there is snow on the 'Snowy Peak' - a few times in the recent decades the cold winds from Antarctica brought snow here. The nesting colonies of two endemic petrel species can be found only on the high-altitude rocks of the Piton de Neiges.

The spectacular extinct volcano, Piton des Neiges.

Cilaos settlement is situated inside a caldera. There is only one road which goes there - it has 400 hairpin curves. From Cilaos there is a spectacular view on the largest extinct volcanoes of the island.

The Piton de Fournaise, is one of the most active volcano in the world. This is a 2632 m tall shield volcano. In some years there are two or three eruptions (you can see a video here). Its age is estimated as 530,000 years. The south-eastern third of the island has been shaped by this spectacular volcano.

The road to the Volcano leads through a martian landscape called the Plaine de las Sables.

The deepest crater (called Commerson crater), is the result of an explosive eruption. It is approximately 300m deep and 250m wide.

Martian landscape of the Plaine de las Sables.

For reaching the summit of the Piton de Fournaise, first we have to descend to the caldera and climb up the 180m high staircase after the trip. :)

Rainbow in the caldera.

One of the most spectacular volcanic formation is the Formica Leo. It got its name from its special shape, which resembles to the trap of the ant-lion. The last eruption of this small crater occurred in the 1700s.

Old lava flow in the foreground, young lava flow in the background.

There are very special lava formations in the caldera.

Pahoahoe type lava surface, which is characterised by fine wrinkles and smooth surface.

The fog comes every afternoon, even on the sunniest day.

Mountains above the clouds.

During the Island Biology Conference, we had a mid-conference excursion to the lava flows of the east coast to explore the primary succession of these special surfaces. There is a couple of kilometres long Lava Route on the east coast, where we could observe a nice chronosequence of the lava flows of the largest recent eruptions. The eruption in 2007 was among the largests, and the lava flew into the ocean. Generally the flow of the lava takes 15-20 years. The first colonizers are lichens and pioneer ferns. There are some pioneer woody species, such as Agarista salicifolia which can colonise the 10-year-old lava surface. Unfortunately there are several alien woody species, especially the Casuarina trees that can quickly colonise the lava. The special 'lava-vegetation' is very sensitive to fire, so there is a need for fire suppression in these habitats.

The first colonizers of the lava are lichens and ferns, such as Nephrolepis abrupta.

A few years later, vegetation cover increases and there are several woody species that can establish. At the left background you can see a dense patch of  the common ironwood (Casuarina equisetifolia) which is among the most competitive alien species on lava flows.

After the largest eruptions, the lava flows 20 km to the Indian-ocean.

The eruption in 1986 increased the area of Réunion with 25 hectares.

Like a miracle: the Notre Dame des Laves church in Sainte Rose remained intact during a large lava flow.

The paper of Strasberg et al. (2005) gives a comprehensive and interesting overview on the original and current habitats of Réunion island. After the conference, we had the possibility to visit and explore most of the habitat types of the island. We give some impressions on the habitats starting in the coast towards the high mountains. In Réunion, like in many other places the coastal and lowland areas have always been subjected to the largest human pressure (agriculture, urbanisation, infrastructural development); therefore, the original habitats of these lowland areas (e.g. savanna, lowland rainforest, inland wetlands) suffered the highest rate of habitat conversion, degradation and invasion of alien species. In the high mountains, there are several undisturbed, natural habitats. However, the population growth, increasing tourism and climatic changes might threaten these habitats in the future.

The coastal lowland areas were originally covered by grassy savanna with scattered palm trees - according to the descriptions of travelers in the 1500s.

The savanna in Réunion in the dry austral winter.

The border of the burnt and unburnt savanna.

Unfortunately, the few remaining stands of the savanna suffered severe degradation due to the encroachment of woody species. Goat pasturing might be a solution that could still help in restoring the original state.

The enemy of the savanna, the white leadtree (Leucaena leucocephala) is a mimosoid species originating from Mexico. It is included in the IUCN list of the 100 most dangerous global invasive species.

The southern coast receives large waves and Antarctic winds.

In the very windy and cool southern coast the 'vacoa', i.e. the screwpine (Pandanus utilis) groves are typical.

The 'utilis' is a very adequate species name: the fruit is a delicacy after cooking, the leaves are perfect material for making baskets and other handcraft items (most of these in the local markets are made from vacoa), and they also use the leaves as roofing material.

We found this panther chameleon (Furcifer pardalis) near the southern coast.

This species is usually much more colorful and decorative. But if chameleons feel cold, they often get black in order to absorb a larger amount of sunlight.

From 2011 there were many serious shark attacks in Réunion. That is why it is not possible to swim in many parts of the coastline except for a few protected lagoons.

The hawksbill turtle (Eretmochelys imbricata) is the most widespread sea turtle here.

Mudskipper on the coastal rocks.

The beach morning glory (Ipomoea pes-caprae) is the most typical plant forming dense mat-systems on the sandy coasts.

Due to the constantly high moisture there are always rainbows everywhere :)

Unfortunately most of the lowland rain forests were converted to sugar cane plantations. During the mid-conference excursion, we went to the wonderful Mare Longue lowland rainforest - where we had a huge rainfall, so this is our only picture from that site :) On the picture, our group is listening to an interesting story about the role of giant turtles in seed dispersal. Several tree species require turtles as seed dispersers - they digest the fruits for a long time, which is important for the induction of germination and can disperse the seeds over long distances. To support this important function, there are several turtle rewilding projects in Réunion.

The most lush tropical vegetation can be found on the wet eastern side of the island.

Mountain forests near Cilaos.

Beard lichen.

Endemic mountain tamarind trees (Acacia heterophylla).

Luxuriant tropical vegetation with fern trees.

The trail in the Bebour-Belouve cloud forest.

That is why it is called cloud forest :)

The South-African calla lily (Zantedeschia aethiopica) is typical in the mountain rain forests.

Cattle pasture in the high mountains, near Nez de Beouf.

Two endemic shrubs: the yellow one is Erica reunionensis and the grey one is Stoebe passerinoides.

The "Hypericum shrub" (Hypericum lanceolatum) is a typical species of the mountain shrublands.

There are nine endemic bird species in Réunion. Most of them are widespread and we can meet them easily, but there are three endemic birds (two petrel species and the Réunion cuckooshrike) which are very rare and endangered.

The 'tectec', i.e. the Réunion Stonechat (Saxicola tectes) is a very kind and absolutely not shy bird.

The endemic Réunion olive white-eye (Zosterops olivaceus).

In Réunion there are very few pollinator insects. Therefore, birds often play their role: here the Réunion olive white-eye on the 'Hypericum shrub' (Hypericum lanceolataum).

A widespread endemic 'pollinator', the Réunion grey white-eye (Zosterops borbonicus).

The endemic Réunion bulbul (Hypsipetes borbonicus).

And the endemic Réunion paradise-flycatcher (Terpshiphone bourbonnensis).

The colonies of the village weavers (Ploceus cucullatus) are widespread in urban and rural areas.

Tropicbirds (Phaethon lepturus) are beautiful and extremely annoying birds, as they are constantly mowing and it is hard to take photos of them :)

Moorhen (Gallinula chloropus) on water lettuce (Pistia stratiotes). Moorhens build their nests on the aquatic vegetation. Wetlands are dominated by alien plants.

Like in many islands, rabbits and rats are the most dangerous invasive animal species. But unfortunately there are many other invasive and alien animal species.

This African snail species was introduced as a promising protein source for animal husbandry - unfortunately, it turned to be not so useful but became widespread throughout the island.

The red-whiskered bulbul (Pycnonotus jocosus) is a widespread invasive species.

Goodbye sunset over the Indian-ocean.

The harbour of Saint Gilles.

Island Biology conference in Réunion island

The 3rd Conference on Island Biology was organised at the University of Saint Denis, La Réunion. Islands are very unique, special and fragile ecosystems, including classical oceanic islands or continental habitat islands with various age and size. Their common point is the uniqueness, isolation and vulnerability which features were discussed in many sections of the meeting. The aim of the conference was to provide a forum for the researchers dealing with various aspects of islands, from dispersal ecology and invasion biology to evolutionary biology. Videos about some lectures can be found in this link - we highly recommend the brilliant plenary lecture of Vojtech Novotny about tropical ecology in Papua New Guinea.

The presentations highlighted that islands harbour several endemic species and are often considered as biodiversity hotspots. However due to their isolation, several functional groups are missing (e.g. pollinators, seed dispersers, carnivores). Their small area, isolation and the functional disharmony makes the biota of islands especially vulnerable to the anthropogenic habitat transformation activities and especially to the human-mediated dispersal and establishment of non-native species, which can later become invasive.

The conference venue: The campus of the University of La Réunion, Saint Denis - like a tropical paradise.

We the Hungarian participants presented our results about the ecology of terrestrial habitat islands. Our poster about the threats of human-mediated seed dispersal on the flora of islands was awarded with the second prize in the poster competition :)

These are the titles of our presentations:

Deák, B., Valkó, O., Török, P., Kelemen, A., Tóthmérész, B.: Diversity of grassland habitat islands: habitat and landscape filters of plant establishment in agricultural landscapes. (oral presentation)

Tóthmérész, B., Hüse, B., Valkó, O., Katona, É., Deák, B.: Grassland habitat islands in urban areas: testing ecological theories. (oral presentation)

Valkó, O., Lukács, K., Deák, B., Kiss, R., Miglécz, T., Tóth, K., Godó, L., Sonkoly, J., Radócz, S., Kelemen, A., Tóthmérész, B.: Alien species on tourists' cloths as novel threats for island floras: Human-dispersed seeds survive and can disperse after laundry washing. (poster)

During the mid-coference excursion and during our holiday after the conference we had the possibility to explore some of the natural beauties of this very interesting island. In the next blog post, we will share some of these experiences :)

The conference village was a very nice place where we could interact with local nature conservationists.

The conference dinner took place in a wonderful villa in Saint Denis.

Colonial atmosphere near the city centre of Saint Denis.

Monument of the first World War.

The Botanical Garden of Saint Denis has a tropical and French character at the same time.

Rue de Paris is one of the most beautiful streets in Saint Denis, with many villas and palaces.

Sunset on the Barachois, the coastal promenade.

The Common Myna (Acridotheres tristis) is among the most common bird species.

A Heliotropium tree - Heliotropium foertherianum.

EDGG Special Issue in Hacquetia

A special issue dedicated to the biodiversity and conservation of Eurasian grasslands has been published on behalf of the Eurasian Dry Grassland Group (EDGG) in the journal Hacquetia. Hacquetia is an international journal of the Slovenian Academy of Sciences, which regularly publishes special issues in cooperation with the EDGG. I have been serving as editor-in-chief in these special issues since 2016.

The papers in this special issue cover a wide range of grassland ecosystems from mountain dry grasslands to lowland loess grasslands, feathergrass steppes and wet grasslands, and focus on the biodiversity values and conservation issues of Palaearctic grasslands. We believe that this compilation will contribute to a better understanding of the ecology of grasslands and support their more effective conservation.

Two papers of the special issue focus on the conservation values of ancient steppic burial mounds (kurgans). The paper of Balázs Deák introduces the Eurasian Kurgan Database which is a new citizen science tool for collecting and sharing data on these important sites (Deák et al. 2019). The paper of Csaba Tóth provides a complex analysis of the geomorphology, soil, flora and fauna of representative mounds in Hungary (Tóth et al. 2019). Anyway, the mounds play a central role in the special issue and they appear also on the cover page :) 

You can read interesting papers about dry grasslands of the Upper Rhone Valley (Dengler et al. 2019a), grazing preferences of water buffaloes in wet grasslands (Tsiobani et al. 2019) and about the effect of wildfires on the steppic arthropod assemblages (Polchaninova et al. 2019). The special issue also includes a report on the activities of the Eurasian Dry Grassland Group (Dengler et al. 2019b) and an editorial paper (Valkó et al. 2019).

The cover photo of the special issue showing that in the intensively used agricultural landscapes, kurgans harbour the last remnants of the steppes. The kurgan on the picture is situated in the Plovdiv region of Bulgaria, and we found several interesting steppic plant on it, such as Goniolimon sp., Elymus elongatus and Ranunculus illyricus (photo by Balázs Deák).

Hacquetia is an international journal indexed on Scopus. It is an attractive publication platform as it has an increasing Cite Score and all articles and colour illustrations are published free and open access. In the EDGG-edited special features we welcome submissions of both botanical and zoological papers related to the biodiversity values or conservation issues of Palaearctic grasslands. The next special issue is planned to be published in December 2020. The call for papers will be published soon.

The papers of the current special issue can be downloaded from the journal homepage.

Please find below the citations of the papers in the current special issue.

Valkó, O., Labadessa, R., Palpurina, S., Burrascano, S., Ushimaru, A. & Venn, S. (2019): Conservation and diversity of Palaearctic grasslands – Editorial to the 5th EDGG special issue in Hacquetia. Hacquetia 18(2): 149-152.

Dengler, J., Widmer, S., Staubli, E., Babbi, M., Gehler, J., Hepenstrick, D., Bergamini, A., Billeter, R., Boch, S., Rohrer, S. & Dembicz, I. (2019a): Dry grasslands of the central valleys of the Alps from a European perspective: the example of Ausserberg (Valais, Switzerland). Hacquetia 18 (2): 161–183.

Dengler, J., Aleksanyan, A., Ambarlı, D., Biurrun, I., Dembicz, I., Kuzemko, A., Török, P., Venn, S. & Vrahnakis, M. (2019b): The Eurasian Dry Grassland Group (EDGG) in 2018–2019. Hacquetia 18(2): 153-160.

Deák, B., Tóth, C., Bede, Á., Apostolova, I., Bragina, T.M., Báthori, F. & Bán, M. 2019: Eurasian Kurgan Database – a citizen science tool for conserving grasslands on historical sites. Hacquetia 18 (2): 185–193.

Tóth, Cs. A., Deák, B., Nyilas, I., Bertalan, L., Valkó, O. & Novák, T. 2019: Iron age burial mounds as refugia for steppe specialist plants and invertebrates – case study from the Zsolca mounds (NE Hungary). Hacquetia 18 (2): 195–206.

Tsiobani, E. T., Yiakoulaki, M. D. & Menexes, G. 2019: Seasonal variation in water buffaloes’ diet grazing in wet grasslands in Northern Greece. Hacquetia 18 (2): 207–218.

Polchaninova, N., Savchenko, G., Ronkin, V., Drogvalenko, A. & Putchkov, A. 2019: Summer fire in steppe habitats: long-term effects on vegetation and autumnal assemblages of cursorial arthropods. Hacquetia 18 (2): 219–237.