My Masters is looking at different features of the Natterjack toads' breeding habitat (including ponds and their surroundings) in order to compare them in terms of land use and breeding success. Since breeding ponds are found on land which undergo more or less important human impacts, it important to understand the actual influences of diverse human activities on the state and quality of the ponds. I am trying to assess how landscape features and environmental quality correlate with the reproductive success of the Natterjack toad.
The features I will try to study are the followings:
- diversity of plants and insects species,
- vegetation and insect biomass,
- vegetation structure (number of layers forming by the various plant individuals),
- flowers quantity,
- soil profil and composition in nutrients,
- water chemistry,
- permanency of the pond,
- margin topography.
These features will be compared, using multivariate analyses, between farmlands, golf courses and Nature reserve locations where the Natterjacks are found breeding. Such activities are wide spread in Ireland, and my results could well be used to look at other possible impacts on different species or natural ecosystems. Indeed, out of the 6.9 million hectares of land forming Ireland, 4.4 million hectares is under agricultural management (Department of Agriculture and Food Production, Teagasc) with an average farm size of 31.4 hectares. 80% of this agricultural land is devoted to grass (silage, hay, pasture) and 11% to grazing (the 9% left to crop production);6.5 million cattle are counted.
Golfing is an important leisure activity in Ireland, and Ireland is renowned worldwide for hosting some of the "greatest", "finest", "genuine" golf courses available. Ireland possesses one quarter of the 160 links courses of the world. The Golfing Union of Ireland counts 408 affiliated clubs (many more non affiliated must be added to have an idea of the overall number of courses) and 250 000 members. Ireland hosts many world famous tournaments and receive many visitors every year for golfing holidays.
The sites that I am studying so far are the Maharees dune system, used for cattle grazing (1 semi-permanent pond, present almost for the whole length of the breeding season), the Stradbally and Dooks golf courses (6 and 3 ponds), and Caherdaniel dune system (2 ponds). I chose these sites amongst the other Natterjacks' breeding sites as they are all based on a sand dune system which facilitates comparisons. These sites represent a good example of the different ways humans have been using the land, and undergo pressures at various scales. During the last field season (April to July 2005) I was able to study plant diversity and vegetation stucture of two ponds on Stradbally golf course, and at the end of the last breeding season I collected invertebrates, using pitfall traps, on all the ponds of the Stradbally and Dooks golf course (to assess secondary production on the sites and assess food availability for adult toads). I have carried out similar measures within the Maharees dune system, and the two ponds in the Caherdaniel dune system reserve.
My aim for the next field season is to extend my work on the vegetation to all the sites cited above, eventually considering two more ponds on the Maharees dune system and three pond areas in Roscullen Island, which is a farmland located on a reclaimed salt marsh.