Thanks to its location, the Lastovo Archipelago has a mild Mediterranean climate, the climate of olives.
Lastovo is one of the sunniest islands in the Adriatic – it has an average of 2700 hours of sunshine per year. The average air temperature is 8.3ºC in January and 24.9ºC in August. Mild summer temperatures last long into autumn, so that autumns on Lastovo are warmer than springs. The most frequent form of precipitation is rain. There is some occasional hail, while snow is extremely rare. An important factor for vegetation is humidity, which makes up for the lack of rain in dry periods. The average annual air humidity is 68%.
The scirocco (SE) and mistral (NW) are the dominant winds, but the bora (NE), libeccio (SW), ponente (strong W wind), tramontana (N), and levanter (E) are also quite frequent.
Lastovo and its archipelago are made up of Jurassic and Cretaceous sedimentary rocks consisting of mainly dolomite, dolomitic limestone and pure limestone.
Hum (417m), Lastovo’s highest hilltop, offers the most beautiful view of Lastovo’s intricate landscape with rounded hills, fields, and bays and coves cutting deeply into the coastline on the one hand, and of the archipelago and endless sea on the other. The second- and third-highest hilltops are Mali Hum (415 m), and Pleševo Brdo (400 m).
Morphologically significant is the interplay of numerous wooded hills and karst valleys – fields (the largest of them being Vinopolje, Lokavje and Prgovo), formed in the impermeable dolomite beds or semipermeable dolomitic limestone beds.
Lastovo’s karst structure was also beneficial to the formation of caves. The most famous of them is Rača Cave in the southeastern part of the island. It was protected as a geomorphological natural monument and archaeological site in 1965. Another famous one, Medjedina Cave, used to be the habitat of the Mediterranean monk seal. Today, it houses large colonies of bats.
The Lastovo archipelago is divided into several groups of islands:
- Škoj od Mrčare
- Bratin otok
- Škoj od Kopišta
- Karlovića tovari
Lastovnjaci (Donji škoji):
- Mladine (Saplun)
- Arženjak Mali i Veliki
- Veliki Golubinjak
- Tajan Mali i Veliki
- hridi: Crna i Bijela
- podvodni greben: Buškanje
Vrhovnjaci (Gornji škoji):
- Gornji i Srednji Vlašnik
- Mrkjenta pod Glavat
- Mrkjenta pod Smokvicu
- Sestrice (Veja, Mala)
- podvodni grebeni:
Biology – land
The Lastovo Archipelago is one of the richest and best preserved botanical areas in the Mediterranean.
The flora on Lastovo is determined by the isolation of the open sea, plenty of sunlight and night humidity, as well as the special and deep Lastovo soil. There are 810 species recorded so far, including endangered species, species extinct elsewhere, endemic and steno-endemic species.
Besides Aurinia leucadea, an interesting and rare plant, one must point out Ampelodesmos mauretanica, a plant only found on Lastovo, as well as the steno-endemic and strictly protected species Biserrula pelecinus ssp. dalmatica.
The flora on the island of Sušac has been affected by the lack of water on scarce soil and constant exposure to strong southerly winds. This specific flora includes 278 plant species; among the eight endemic ones, one must point out Brassica cazzaem, which grows in the cracks of rocks along and near the shore.
Around 70% of the islands’ surface is covered with forest; besides Mljet, Lastovo has the most forest cover among Croatia’s islands. It is mostly covered with maquis – the most beautiful tree is strawberry tree (Arbutus unedo), but it is significantly covered with holm oak (Quercus ilex) and aleppo pine (Pinus halepensis). Mushrooms can also be found under the forest cover.
Houses on Lastovo are adorned with Mediterranean plants growing around them: almond, lemon, orange, palm and carob trees. This environment also suits medicinal plants such as sage, mint, milfoil, rosemary, lavender, fennel and camomile. Grapevines and olive trees predominate among cultivated plants.
There is also an abundance of animal life. 175 vertebrate species have been recorded so far; 71 of them are endangered at the national and 37 at the European level.
Lastovo’s caves host bats that use them either as dens or breeding sites; Medjedina Cave provides shelter for 3 endangered bat species – the Mediterranean Horseshoe Bat (Rhinolopus euryale), Geoffroy’s Bat (Myotis emarginatus) and Greater Horseshoe Bat (Rhinolophus ferrumequinum).
The Lastovo Archipelago is an important resting site for numerous migrant birds and also the nesting site for the rare Mediterranean shearwater and Cory’s shearwater (Calonectris diomedea). About 70% of Croatia’s population of the globally endangered Audouin’s Gull (Larus audouinii) nests on the island groups of Lastovnjaci and Vrhovnjaci. The rare Eleonora’s Falcon (Falco eleonorae) also nests on the cliffs of Struga (the large rock).
It is interesting that there are no venomous snakes on the Archipelago; the only snake is the Caspian whipsnake (Dolichophis caspius). The Lastovo Archipelago is also the habitat of steno-endemic lizards – the Dalmatian ruin lizard (Podarcis sicula adriatica) and the Lastovo wall lizard (Podarcis melisellensis n. ssp.).
The area has an abundance of micro-fauna, especially insects, spiders and snails.
Biology – sea
248 sea species demonstrate the richness of the marine world in the Lastovo Archipelago. This small area hosts as many species as a wide area of the Central and Southern Adriatic. There is a seasonal inflow of nutrients from deep waters, which fosters the proliferation of marine life.
Rocky seabed regions are covered with abundant colonies of photophilic algae, while shallow nearshore seabeds are covered with endangered and protected Neptune Grass (Posidonia oceanica). This species provides a very important spawning habitat and shelter to various sea species. Skrivena Luka is an exceptionally rare habitat of the green alga Caulerpa prolifera, the only autochthonous Caulerpa in the Adriatic.
Thanks to the abundance and wide variety of zooplankton, the Park’s sea world is rich with corals, sponges, molluscs, bryozoans, Echinoidea, crustaceans and numerous other species, so that the links in the chain of marine life are very strong. 330 species of invertebrates have been noted so far, of which 20 are on the list of endangered species.
Outstandingly beautiful are colonies of the Gerardia (Gerardia savaglia), precious coral (Corallium rubrum) and endemic hidden orange coral (Madracis pharensis)
The foreshore is habitat to various marine gastropods – topshells and limpets. There are also sea urchins, octopuses and cuttlefish. Trademarks of the rocky seabed around Lastovo are colonies of the European spiny lobster, European lobster, Mediterranean slipper lobster and European spider crab. Rare species of sea snails – Triton’s trumpet (Charonia tritonis sequenza), zoned mitre (Mitra zonata) and giant tun (Tonna galea) – also live here.
Fish species characteristic of this area are the black scorpionfish, red scorpionfish, dusky grouper, common dentex, black seabream, surmullet, forkbeard, peacock wrasse, Mediterranean moray eel, European conger eel and other. Tuna, greater amberjack and swordfish can also be found here.
Several dolphin species, such as the short-beaked common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops truncatus) and Risso’s dolphin (Grampus griseus) can often be seen in the open waters of this area, as well as the loggerhead sea turtle (Caretta caretta) and green turtle (Chelonia mydas).
The solitary rocks of Medjedina Cave used to be the home to the Mediterranean monk seal (Monachus monachus); random encounters of Lastovo’s inhabitants with the former tenant keep the hope of its return alive.