Náttúrufræðingurinn

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Náttúrufræðingurinn - 1995, Side 104

Náttúrufræðingurinn - 1995, Side 104
2. It could be snow cover as snowpatch plants such as Vaccinium myrtillus increase as we go up axis 2. Fig. 7 and Table 3 show the relation- ship between different plant species and the result of the ordination. The TWINSPAN program gave four groups (Fig. 8). Good agreement was between the TWINSPAN classification and the ordination (Fig. 9). The most common woody plants for groups A/B were Empetrum nigrum, Betula nana and Calluna vulgaris, but in groups C/D willows, especially Salix phylicifolia, were important. Ptarmigan numbers in sample points and the site ordination show that the greatest number of birds are in the lower left corner of the graph and numbers decrease as we go up both axes (Fig. 6 and Fig. 12). Similar picture emerges if we compare ptarmigan numbers and the TWINSPAN classification (Table 4). The study shows that there is a connection between type of vegetation and ptarmigan den- sity. Certain types of heathland vegetation (Betula nana heaths, Steindór Steindórsson 1981) are characterized by a low density of ptarmigan as compared with other types (heather heaths). This difference in density is maintained all through the 10-year ptarmigan cycle (Fig. 13). The author regards this as the first step to establish whether remote sensing can be used to determine breeding distribution and population size of Rock Ptarmigan over extensive areas in Iceland. The next logical step would be to study whether we can discern heathlands from the other main vegetation types by means of remote sensing and further classify the different types of heathlands and connect that classification with ptarmigan density (see Palmeirim 1988, Avery and Haines-Young 1990, Ferguson 1991, Pearce 1991, Wallin et al. 1992). PÓSTFANG HÖFUNDAR / AUTHOR'S ADDRESS Ólafur K. Nielsen Náttúrufræðistofnun Islands/ Icelandic Institute of Natural History Pósthólf/Box 5320 IS-125 Reykjavík Iceland Viðauki/Appendix Listi yfir jurtir sem komu fyrir í gróður- mœlingum í Suður-Þingeyjarsýslu í júní til ágúst 1993. Plöntulieiti eru skv. Herði Kristinssyni 1986. - List of plants re- corded. Jafni1 Elfting2 Beitieski Einir Brjóstagras Fjalldrapi Lambagras Kornsúra Súrur' Geldingahnappur Grávíðir Grasvíðir Loðvíðir Gulvíðir Krækilyng Sortulyng Beitilyng Sauðamergur Aðalbláberjalyng Bláberjalyng Holtasóley Maðra4 Blóðberg Smjörgras Vallhumall Undafífill Túnfífill Lycopodiaceae Equisetum sp. Equisetum variegatum Juniperus communis Thalictrum alpinum Betula nana Silene acaulis Bistorta vivipara Rumex sp. Armeria maritima Salix callicarpaea Salix herbacea Salix lanata Salix phylicifolia Empetrum nigrum Arctostaphylos uva-ursi Calluna vulgaris Loiseleuria procumbens Vaccinium myrtillus Vaccinium uliginosum Dryas octopetala Galium sp. Thymus praecox Bartsia alpina Achillea millefolium Hieracium spp. Taraxacum spp. 'Ekki var greint á ntilli litunarjafna Diphazium alpinum, lyngjafna Lycopodium ammotinum, mosajafna Selaginella selaginoides og skolla- fingurs Huperzia selago. - Lycopodiaceae re- fers to Diphazium alpinum, Lycopodium amm- otinum, Selaginella selaginoides and Huperzia selago. 2Ekki var greint á milli klóelftingar Equisetum arvense og vallelftingar E. pratense. - Equi- setum sp. refers to Equisetum arvense and E. pratense. 3Ekki var greint á milli túnsúru Rumex acetosa og hundasúru R. acetosella. - Rumex sp. refers to Rumex acetosa and R. acetosella. 4Ekki var greint á milli hvítmöðru Galium normanii og gulmöðru G. verum. - Galium sp. refers to Galium normanii and G. verum.
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