Fourth National Report to the cbd – malta executive Summary




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1.0 Overview of Biodiversity Status, Trends and Threats

This chapter provides an overview of the status and trends of biodiversity in the Republic of Malta (or the Maltese Islands), with the main aim being to inform decision-makers. References used for building this chapter and other chapters of this report are listed in Appendix II unless otherwise indicated (as hyperlinks or sources for further information). These publications should be referred to for obtaining any further information on the subject of interest.

    1. Biodiversity of the Maltese Islands

The Maltese archipelago is located in the central Mediterranean and is approximately 93 km south of Sicily and 290 km north of the African Continent. The archipelago consists of a group of three islands aligned in a north west - south east direction: Malta and the two smaller islands of Gozo (Maltese: Għawdex) and Comino (Maltese: Kemmuna), together with a series of smaller uninhabited islets, which are found scattered around the 271 km coastline of the islands. Islets such as Filfla, St Paul’s Islands (Maltese: Il-Gżejjer ta’ San Pawl/Selmunett) and Fungus Rock (Maltese: Haġret il-Ġeneral) are of a very high conservation value in that each harbours endemic species as well as distinct plant communities that are solely restricted to these islets. For instance, a species of giant leek (Allium sp. nov. aff. commutatum) which may be endemic but remains to be studied, is essentially confined to the small islets. Filfla supports the largest breeding colony (between 5,000 to 8,000 pairs) of the European Storm-Petrel (Hydrobates pelagicus melitensis). The Maltese Islands are sloping towards the north east. This has created two types of Maltese coastlines – the sheer cliffs and screes bordering the south west and west of Malta and Gozo in contrast to the gently sloping shores to the north east of Malta.

The Maltese Islands form part of the semi-arid region of the Mediterranean and hence exhibit a bi-seasonal climate, which is typical of the region. The Maltese Islands are heavily influenced by the strength and frequency of winds namely the north-westerly and north-easterly winds. The geology of the Maltese Islands is mainly constituted by different types of limestone deposited during Oligo-Miocene era, with some marls and clays. Limestone is Malta’s principal non-renewable mineral resource, whereby Globigerina Limestone (softstone), is used for the manufacture of limestone blocks and other products for use in the construction industry, while Lower and Upper Coralline Limestone is mainly used for road construction and in the production of concrete. The topography of the islands is pretty much low-lying with only low hills and terraced slopes; there are no mountains, rivers or lakes present. The dearth of freshwater has contributed to the overall rarity of freshwater flora and fauna in the Maltese Islands, especially when considering those species that are dependent on a relatively constant supply of water.

A limited, yet diverse, array of ecosystems is found in the islands and its surrounding waters. One can appreciate an interesting variety of flora and fauna, especially when considering the relatively small land area (316km2), the limited number of habitat types and the intense human pressure. Indeed, when considering both the land area and the territorial waters, the islands are fairly rich in native plant and animal diversity, as well as habitat diversity. Such natural heritage is of particular importance for the well-being of the Maltese population. It is noteworthy that Malta’s isolated yet central position in the Mediterranean has led to some species exhibiting elements of Western Mediterranean, Eastern Mediterranean, and North African and Sicilian affinity (including circum-Sicilian islands). The historical interchange of species has particularly influenced the composition of plants and animals that currently inhabit the Maltese Islands. Indeed, the occurrence, geographic distribution and affinity of such species has been analysed by local ecologists in their study of the biogeography of the Maltese Islands. For instance, the family of the door-snails (Clausiliidae) (such as the Genera Lampedusa and Muticaria) have been used as the subject matter for investigating evolutionary processes and providing insight to the zoogeography on a Mediterranean level and especially in expounding the biogeography of the Maltese Islands (vide for instance Giusti et al.,1995).

The land use pattern of the Maltese Islands is illustrated by mapped CORINE land cover data (Figure 1 and Table 1 show 2006 data). Approximately 19% of land area that is naturally vegetated lies mostly in coastal locations. The land use pattern of the archipelago has remained largely constant between 2000 and 2006; development on the island of Malta is mainly concentrated in the north-eastern part of the mainland, while Gozo is characterised by pockets of development, mainly l
ocated in the southern and central part of the island (SOEI 2007 – Land Cover by Type).



1.1.1 Ecosystem and Habitat Diversity

Maltese ecosystems and habitats can be classified as shown in Table 2. Further details are provided in the following paragraphs.



Natural and Semi-natural Ecosystems

Main Habitats

Successional Ecosystems

Evergreen woodland

Maquis

Garigue

Steppe

Inland Water Ecosystems / Freshwater Wetlands

Valley watercourses

Permanent natural ponds

Permanent natural springs

Temporary rainwater ponds/Karstland pools

Coastal Ecosystems

Adlittoral Habitats

Coastal wetlands/Saline marshlands

Sand dunes

Sea cliffs / Boulder screes

Supralittoral Habitats

Gently sloping rocky shores

Soft substratum shores

Mediolittoral Habitats

Habitats on bioconstructions (Vermetid/ Coralline algal rim)

Marine Ecosystems

Infralittoral habitats

Habitats on hard substrata (Posidonia ‘barrier reefs’)

Habitats on soft substrata (Seagrass meadows: Cymodocea nodosa, Posidonia oceanica)

Habitats on biogenic concretions (Cystoseira communities, Dictyopteris belts, Corallina elongata belts, Cladocora caespitosa banks)

Circalittoral habitats

Habitats on hard substrata (Coralligene communities)

Habitats on soft substrata (Mäerl communities)

Agro-ecosystems

Habitats shaped by different farming practices

Dry farmed land

Irrigated land

Afforested Areas

Areas that have been planted by man. In the past afforestation led to the planting of alien trees. Nowadays indigenous trees are solely being planted with the purpose of not only creating areas of a recreational value but also to attract fauna to the area.

Table 2 – Types of ecosystems and habitats found in Malta

Malta’s most characteristic vegetation communities are those that pertain to the sclerophyll series. The four communities - woodland remnants, maquis, garigue and steppe - undergo vegetational succession in response to both natural and man-made disturbance/stress. More often than not, these habitats occur in a mosaic fashion. Moreover various sub-types of these communities exist – for instance with regards to garigue one can mention phrygana, labiate garigues and pre-desert scrub. The highest expression is the “evergreen wood”, which has practically disappeared from Malta since the first settlers colonised the islands 7000 years ago, due to the fact that they felled trees for procuring wood (for building and to make tools), and for clearing land for agriculture, apart from having introduced grazing animals that prevented regeneration of saplings. Moreover, trees were destroyed in great numbers during the Turkish invasion in the 16th century, namely, to make wood scarce for the defenders. Trees were also felled as a source of wood during both World Wars (see Lanfranco, 2000). What remains nowadays are pockets of evergreen wood remnants generally composed of large evergreen trees such as Holm Oak (Quercus ilex) and Aleppo Pine (Pinus halepensis). The various microclimates and shelter available to species inhabiting this habitat type, means that such species are unique to this habitat. Buskett qualifies as the only locality which can be said to represent “mature woodland” in the Maltese Islands.

The second stage is the “maquis”, dominated by a variety of small trees and large shrubs, including trees introduced in antiquity in view of their usefulness. A particularly interesting maquis community is that dominated by Malta’s national tree - Sandarac Gum Tree (Tetraclinis articulata). Although once a widespread species, Sandarac Gum Tree is now rather rare in the natural environment. Maquis also constitutes a rich undergrowth of large herbs and lianas. The structural complexity of this habitat supports a diverse biota and hence various niches are formed. The third stage is the “garigue”, a shrub community that typically forms on karstic substrate particularly on large expanses of limestone with shallow pockets of soil and rock fissures, in exposed areas. Garigue also constitutes a rich diversity of herbaceous plants, while serving as a home to around 500 species of flowering plants. This habitat also supports many rare species including orchids and irises. The fourth stage is the “steppe”, which supports a high diversity of herbaceous plants but lacks woody species. It is in fact represented by grasses, thistles, umbellifers and geophytes and is characterised by a uniform layer of soil which is low in nutrients. Steppe is the pioneering stage, but can also derive from maquis and garigue as a result of some form of degradation, such as due to fire and grazing. Grasslands are important for many invertebrates and also serve as nesting sites for certain bird species.

Apart from the sclerophyll series, other significant terrestrial ecosystems include freshwater and coastal ones, mostly being represented by minor yet more specialised habitat types, some of which have suffered extensive range contraction over the years. Such ecosystems are considered to be very crucial from a conservation and ecological point of view, supporting native communities that are of high conservation value, while playing important ecological roles.

Freshwater ecosystems are essentially vulnerable systems in Malta as in other parts of the world. They include valley watercourses, permanent ponds and springs, and temporary rainwater rockpools. Watercourses are the commonest type of freshwater habitat on the islands, albeit restricted in range. While being one of the most species-rich habitats, it is also one of the most intensively exploited. Some of the plants that colonise this habitat are rare on a national scale; the most well-known animal from this habitat is the only native amphibian found in Malta – the Painted Frog (Discoglossus pictus pictus). In general, the greater part of local flora and fauna reliant on water during some part of their lifecycle are found in valley watercourses, which are generally dry during certain months of the year whilst water flow is normally limited to the wet season. Certain valleys however drain springs originating from the perched aquifers and retain some surface water even during the dry season. The few remaining permanent springs support unique species, being very rare and with a restricted distribution, such as the endemic subspecies of the Mediterranean Freshwater Crab (Potamon fluviatile lanfrancoi). These pools are of great local interest since they represent the only natural standing water bodies in the islands. Rockpools, which are pools in karstic limestone depressions that originate as a result of flowing water, and, which collect freshwater in the wet season, support a number of rare species specialised to this habitat.

In view of the relatively small size of the Maltese archipelago, the entire State can be considered to be essentially coastal. Indeed, all habitat types are under some degree of maritime influence. Coastal ecosystems per se, include transitional coastal wetlands, saline marshlands, sand dunes, rupestral habitats and rocky shores, amongst others. Saline marshlands are very scarce in Malta, with only a few extant noteworthy marshes, and another few sites which are highly degraded. Biota that inhabit marshlands have become specialised to withstanding harsh environmental conditions that predominate. They have done this through changes in behaviour and physiology and hence are considered as habitat specialists restricted to this type of habitat. For instance, a number of invertebrates are only known from this habitat type. Species found in local marshlands include for instance Sharp Rush (Juncus acutus), Sea Rush (Juncus maritimus), Sea Clubrush (Bolboschoenus maritimus) and Common Reed (Phragmites australis), amongst others. Each marshland is also typified by its own characteristic habitat features and assemblage of species. Different species assemblages colonise transitional coastal wetlands during different periods of the year. For instance, during the dry period, conditions favour brackish water species since water reaching these depressions is seawater carried by wind and wave action. Coastal wetlands in Malta are important as stop-over sites for migratory avifauna. At present, there are very few extant marshes that are noteworthy in terms of conservation value, the largest being L-Għadira (Malta). Transitional coastal wetlands are then represented by only a few, minor examples. Over the years many sand dunes have been lost and, nowadays, this habitat type is extremely restricted in the Maltese Islands. Presently there are only few that still persist and are amongst the rarest and most threatened of local ecosystems. The dune system at Ir-Ramla (Gozo) is the largest and most representative in the Maltese Islands and has suffered the least alteration by man. The dune system is characterised by the embryo dune, i.e. the most seaward zone of the dune where perennial plants are first encountered, followed by the mobile dune. The latter is characterised by the following sequence of sub-zones: a low dune (sparsely vegetated by plants such as Sand Couch Grass - Elytrigia juncea and, Sea Holly - Eryngium maritimum); a semi-consolidated dune (characterised by Carnation Spurge - Euphorbia terracina, Sea Daffodil - Pancratium maritimum and, Spiny Echinophore - Echinophora spinosa), and a fixed dune (vegetated with a dense thicket of salt tolerant shrubs such as Sand Restharrow (Ononis natrix subsp. ramosissima). Maltese sand dunes also have characteristic invertebrate fauna namely nematodes, annelids, several insects, amphipods, and isopods.

Rupestral communities are both of national and international importance. Maltese sheer seaside cliffs and screes vary from 0m up to 250m in altitude and are composed of coralline limestone, with calcareous soils. They extend along the south-west coast of the main islands and are an important natural habitat since they harbour a variety of interesting species, including endemic plants, with Maltese Everlasting (Helichrysum melitense) being solely restricted to the western cliffs of Gozo, and found nowhere else in the world. Cliffs also support interesting fauna, including one of the rarest animals found in Malta – the endemic Maltese Door-Snail (Lampedusa melitensis), which is restricted to crevices and cavities in boulders that have detached from cliff edges. Coastal cliffs are also noteworthy since they provide shelter and a breeding habitat for many bird species, including seabirds, such as Cory’s Shearwater (Calonectris diomedea); Yelkouan Shearwater (Puffinus yelkouan) and European Storm-Petrel (Hydrobates pelagicus melitensis). When compared to other terrestrial habitats, cliff communities have suffered moderate anthropogenic effects, and various areas have been relatively untouched by man and these serve as particularly important refugia for endangered and rare species including endemic ones. Indeed, coastal cliffs immensely contribute to the natural heritage of the Maltese Islands, and are deemed of high priority for protection, conservation and management.

Low-lying rocky coasts are colonised by halophytic vegetation, which grows in isolated patches in shallow saline soil which accumulates in rock pockets, with the species mainly forming the vegetational community referred to as Crithmo-Limonietea, which also include a number of endemic species.

As regards the marine environment, different macrobenthic assemblages are found in marine waters around the Maltese Islands and include communities of photophilic algae on hard substrata; meadows of Neptune Grass (Posidonia oceanica); meadows of Lesser Neptune Grass (Cymodocea nodosa), photophilic and sciaphilic communities; communities of bare, well-sorted sand, and mäerl communities. Seagrass meadows, and communities based on Cystoseira species, are possibly the most important natural habitat in Maltese waters in terms of productivity since they provide shelter and a place for breeding and feeding for numerous marine species.

Man-made habitats shaped by various actions and activities brought about by man since the time the first settlers set foot on the islands also characterise the physiognomy of the islands. Agricultural land in the Maltese Islands accounts for just over half (51%) of total land area. Agroecosystems are shaped by the different farming practices employed: dry farmed land (Maltese: Raba' bagħli) or irrigated land (Maltese: Raba' saqwi). Agroecosystems are supported by organisms that are important in nutrient cycling, pest and disease regulation, pollination, soil and water conservation, and maintenance of soil fertility. In turn, agriculture has played an important role in moulding the rural landscape via a patchwork of terraced cultivated and fallow fields. The traditionally built stone rubble walls which delineate land parcels, serve as important ecological corridors for instance for native reptiles, such as Moorish Gecko (Tarentola mauritanica), Maltese Wall Lizard (Podarcis filfolensis), Ocellated Skink (Chalcides ocellatus), Western Whip Snake (Coluber viridiflavus), and Leopard Snake (Elaphe situla), together with species such as shrews. They also serve as a refuge for insects and molluscs, amongst others. Rubble walls, as stabilising structures, are important in soil conservation. Agricultural land provides a food supply for insectivorous birds that breed in the Maltese Islands, like Sardinian Warbler (Sylvia melanocephala), Spectacled Warbler (Sylvia conspicillata), Corn Bunting (Emberiza calandra), and Short-Toed Lark (Calandrella brachydactyla). Very rare plant species are also found in fallow fields such as Wild Tulip (Tulipa sylvestris).

The urban fabric, which covers approximately 22.3% of land area, is also important for certain species that have managed to adapt to living alongside man and use man-made structures as refuges. Such species include various birds (e.g. Spanish Sparrow - Passer hispaniolensis), various invertebrates (e.g. House Centipede - Scutigera coleoptrata), and various reptiles (e.g. Turkish Gecko - Hemidactylus turcicus, Leopard Snake - Elaphe situla and Maltese Wall Lizard - Podarcis filfolensis). Other species that are encountered within urban environments include House Mouse (Mus musculus), shrews, and bats, with the latter roosting in old and abandoned dwellings and bastions.

1.1.2 Species Diversity

Various in-depth accounts of Maltese biodiversity have been undertaken over the years and can be traced all the way back to the 1800s. Such research, both published and unpublished, has considerably advanced the local knowledge of Malta’s natural heritage. Isolation and long-term evolution have led to some species being strictly endemic to the Maltese Islands. Sub-endemic species also occur, and include Siculo-Maltese, Hybleo-Maltese and Pelago-Maltese endemics. An estimate of the number of endemics and sub-endemics for some taxonomic groups is given in Table 3 (overleaf). However, many species are still under study. Apart from the intrinsic importance of endemic species, such species contribute a great deal to the uniqueness of Malta’s natural heritage.

Considering the flora, vascular plants are the most taxonomically diverse and are also the most studied group. Malta’s indigenous flora amounts to some 1,200 species of flowering plants with around 25 strict endemics (2%). The Maltese plant endemics: Maltese Rock Centaury (Palaeocyanus crassifolius), Maltese Cliff-Orache (Cremnophyton lanfrancoi) and Maltese Everlasting (Helichrysum melitense) are included amongst the top 50 Mediterranean Island Plants at the brink of extinction, since they are critically endangered. They are in fact strictly protected in Malta, and are also included as species of European Community Importance. The least diverse group of flora is that of the gymnosperms whereby only two conifer species are native. Considering marine plant diversity, this is mainly represented by micro-algae and macro-algae (seaweeds), including a variety of taxonomic groups, such as blue-green, brown, red and green algae. Five species of seagrasses are recorded – with two species possibly extinct (Source: Lanfranco, 1989 in the Red Data Book). Posidonia oceanic, which is endemic to the Mediterranean, forms one of the most important marine habitats types in Maltese territorial waters, as it serves as a feeding and nursing ground for various fauna that seek shelter amongst the blades of its dense foliage.

FAUNA

Invertebrates (excluding insects)2

ca. 27 endemic species

ca. 14 sub-endemic species



Insecta3

ca. 51 endemic species

ca. 36 sub-endemics

Many species are still under study


Vertebrates4

1 endemic subspecies of shrew (Crocidula sicula calypso)

5 endemic subspecies of Maltese Wall Lizard (Podarcis filfolensis)



FLORA

Fungi (macro and microfungi)5

ca. 134 possibly endemic species – further research is required Some groups such as the microfungi are understudied.

Lower Plants (12 Lichens and 2 Bryophyta)

ca. 14 endemic species

Many species are still under study



Higher Plants (Angiosperms)

ca. 25 endemic species

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