Leit a­ hentugum grastegundum til uppgrŠ­slu ß hßlendi

H÷fundur┌tgefandi┌tgßfußr┌tgßfusta­ur
┴slaug HelgadˇttirB˙na­arfÚlag ═slands, BŠndaskˇlinn ß Hvanneyri, Rannsˇknastofnun landb˙na­arins, Rannsˇknast÷­ SkˇgrŠktar rÝkisins, Tilraunast÷­ hßskˇlans Ý meinafrŠ­i, Vei­imßlastofnun1988ReykjavÝk
Rit┴rgangurT÷lubla­Bls.
B˙vÝsindi111-33

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Frß vefstjˇra: Greinina Ý heild sinni er a­ finna Ý pdf-skjalinu hÚr a­ ofan

YFIRLIT

Fjalla­ er um ni­urst÷­ur ˙r grasstofnatilraunum ■ar sem meginmarkmi­i­ var a­ leita a­ hentugum grasstofnum til uppgrŠ­slu. TvŠr tilraunara­ir eru teknar til uppgj÷rs. Vi­ Gunnarsholt, B˙rfell og Hrauneyjafoss var sß­ 47 grasstofnum vÝ­s vegar a­ sumari­ 1980 (tilraunar÷­ I) en ß Au­k˙lu- og Eyvindarsta­ahei­i var sß­ 10 stofnum sumari­ 1981 ß ■remur uppgrŠ­slusvŠ­um vegna Bl÷nduvirkjunar vi­ Sey­isß, Sandß og ß ÍfuguggavatnshŠ­um (tilraunar÷­ II). ═ fyrri tilraunar÷­inni voru tilraunareitir ß fri­u­u landi en Ý ■eirri seinni var helmingur hvers reits girtur af.

A­eins ÷rfßir stofnar reyndust nŠgilega vetrar■olnir til ■ess a­ unnt sÚ a­ mŠla me­ sßningu ß ■eim. ┴ fri­u­u landi bar beringspuntur frß Alaska af ÷llum ÷­rum stofnum. Fast ß hŠla honum komu Ýslensk snarrˇt og t˙nvingulsstofnarnir Leik og Sturla. Snarrˇt ■oldi hins vegar beit best allra stofna.

K÷nnu­ voru ßhrif ßbur­arsveltis ß endingu stofnanna. ═ ljˇs kom a­ vallarsveifgras ■oldi ßbur­arskort a­ jafna­i betur en t˙nvingull. Snarrˇt bar af ÷­rum stofnum ß Au­k˙lu- og Eyvindarsta­ahei­i, einkum ß beitta hluta tilraunanna, en h˙n var aftur ß mˇti lÚleg Ý tilraunar÷­ I.

Gengi stofnanna var nokku­ misjafnt eftir tilraunast÷­um. RŠ­ur ■ar ugglaust mestu misjafnt ve­urfar og ˇlÝkir jar­vegs■Šttir. ŮvÝ er mŠlt me­ ■vÝ a­ sß­ ver­i bl÷ndu af vel a­hŠf­um stofnum og nßtt˙ru÷flunum sÚ lßti­ eftir a­ vinsa ˙r ■ß stofna sem best henta ß hverjum sta­.

SUMMARY

In search of suitable grass varieties for reclamation purposes in Iceland

This paper describes results from two experimental series of variety trials for reclamation purposes at high elevations in Iceland. The first series was laid out in 1980 at Gunnarsholt, B˙rfell and Hrauneyjafoss (experiment I) where 46 grass varieties of contrasting geographic origin were compared. All the plots were protected from grazing. The other series was sown a year later at Audk˙lu- and Eyvindarstadaheidi (experiment II) and only the 10 best adapted varieties that were available were included. One half of each experimental plot was fenced off, whereas the other half was subjected to heavy grazing by sheep.

All experimental plots received the equivalent of 70 to 100 kg N/ha in a compound fertilizer (26N,26P205 or 23N,14P205 or 17N,17P205,17K20). Starting in 1984 one half of each plot received no fertilizer until 1986. It was thus possible to estimate the effects of fertilizer shortage on the persistence of the varieties.

The results revealed that only very few grass varieties are winter hardy enough to survive the harsh conditions that prevail at the experimental sites. These varieties are all of northern origin. The superior varie ties were: Deschampsia beringensis, IAS 19 from Alaska, Deschampsia caespitosa, a wild population from Iceland, Festuca rubra, Leik from Norway, and Sturla from Iceland. Varieties of Poa pratensis were in general inferior, but of these, Fylking from Sweden gave the best results. On the grazed plots in experiment II the Icelandic population of D. caespitosa surpassed all other varieties, whereas D. beringensis suffered from the heavy grazing and had virtually disappeared at the end of the experimental period.

It appeared that P. pratensis was generally more resistant to a shortage of fertilizer than F. rubra. In experiment II D. caespitosa was superior to all other varieties on plots that had received no fertilizer, especially under grazing, but this was not the case in experiment I.

The performance of the grass varieties depended on the test locations. In experiment I differences can largely be attributed to varying climatic conditions at the test sites, whereas in experiment II differences resulted more from varying snow cover and soil conditions. It is suggested that it is an advantage to sow a mixture of adapted grass varieties for reclamation and let nature select the most suitable combination at each location.


INNGANGUR

┴ undanf÷rnum ßrum og ßratugum hefur LandgrŠ­sla rÝkisins lagt mikla ßherslu ß a­ grŠ­a upp grˇ­urvana land me­ dreifingu ßbur­ar og grasfrŠs. ┴ ßrinu 1985 var t.d. sß­ Ý um 1100 ha lands fyrir framkvŠmdafÚ LandgrŠ­slu rÝkisins (AndrÚs Arnalds, 1986). UppgrŠ­sla af ■essu tagi er dřr og ■vÝ er mj÷g mikilvŠgt a­ vanda vel vali­ ß ■eim grasstofnum sem sß­ er.

Ůeir grasstofnar, sem lengstum hafa veri­ nota­ir til uppgrŠ­slu, hafa yfirleitt enst illa ß uppgrŠ­slusvŠ­unum. Gilti ■a­ einkum um danska t˙nvingulsstofna sem
nota­ir voru fyrr ß ßrum. Upp ß sÝ­kasti­ hafa ■ˇ ■olnari stofnar veri­ nota­ir Ý rÝkari mŠli. UppgrŠ­sla lands me­ frŠi og ßbur­i gengur misvel og eru ■a­ einkum ßhrif umhverfisins sem rß­a ■ar mestu um (Sveinn Runˇlfsson, 1987).

Jar­vegur ß uppgrŠ­slusvŠ­unum er grˇfur og snau­ur af lÝfrŠnum efnum (Ëlafur Arnalds o. fl., 1987). Hann er lÝtt vatnsheldinn og ■urrkur hrjßir ■vÝ oft ■ann grˇ­ur sem ■ar vex. Til vi­bˇtar kemur a­ ve­urfar er oft ˇhagstŠtt, sÚrstaklega ß svŠ­um inni Ý landi. Sumur eru stutt og k÷ld og frosth÷rkur oft miklar ß vetrum. Skortur ß fullnŠgjandi vetrar■oli er sennilega algengasta ors÷k ■ess a­ sß­gresi endist stutt Ý uppgrŠ­slum, sÚrstaklega ß hßlendi. Margir ■Šttir geta leitt til dau­a plantnanna yfir veturinn. Ef su­lŠgir stofnar eru nota­ir er vel ■ekkt a­ ■eir vetra sig ekki nˇgu snemma ß haustin og hafa ■vÝ ekki safna­ nŠgum nŠringarfor­a fyrir veturinn (t.d. Klebesadel, 1985). Pl÷ntur geta sÝ­an misfarist af řmsum ors÷kum, t.d. beinum frostska­a, frostlyftingu ß jar­vegi, ■urrki, Ýshulu og svelti (Larsen og Arsvoll, 1984). Oft lifa pl÷ntur sŠmilega af veturinn, en eru veiklulegar og gefa litla sem enga uppskeru. Er ■ar um a­ kenna lÚlegri a­hŠfingu sem getur orsakast af ˇfullnŠgjandi vetrar■oli og/e­a ˇnˇgum vexti og for­as÷fnun vi­ lßgt hitastig yfir sumari­.

Leit a­ hentugum grasstofnum til uppgrŠ­slu hˇfst snemma. ┴ ßrunum milli 1945 og 1960 var sß­ řmsum grastegundum og stofnum vi­ Gunnarsholt. A­eins ÷rfßir stofnar lif­u lengur en tv÷ ßr (Sturla Fri­riksson, 1952; Runˇlfur Sveinsson, 1953; AndrÚs Arnalds o. fl., 1978). ┴ hßlendinu voru einnig lag­ir ˙t uppgrŠ­slureitir, ■ar sem sß­ var řmsum grastegundum og stofnum (Sturla Fri­riksson,1960, 1969a, 1969b, 1971.).Er enn fylgst me­ sumum ■essara sßninga og eru Ýslenskur t˙nvingull og snarrˇtarpuntur lang■olnastir ■eirra grasa sem sß­ var (Tryggvi Gunnarsson, munnlegar heimildir). ┴ri­ 1975 var sÝ­an gert nřtt ßtak Ý a­ leita hentugra grasstofna til uppgrŠ­slu, bŠ­i ß lßglendi og hßlendi. Sß­ var 403 stofnum Ý smßreiti, en eftir tvo vetur reyndust einungis tŠpur fjˇr­ungur ■eirra ■rÝfast enn sŠmilega (AndrÚs Arnalds o.fl., 1978). ┴ grundvelli ni­ursta­na ˙r athugun ■essari var bestu stofnunum sß­ Ý nřja tilraunar÷­ vi­ Gunnarsholt ß Rangßrv÷llum, vi­ B˙rfell Ý Gn˙pverjahreppi og vi­ Hrauneyjafoss ß LandmannaafrÚtti sumari­ 1980 (tilraunar÷­ I). Voru ■ar bornir saman 46 stofnar af řmsum uppruna. Sumari­ eftir voru einnig lag­ir ˙t tilraunareitir ß Au­k˙lu- og Eyvindarsta­ahei­i Ý tengslum vi­ uppgrŠ­slu vegna Bl÷nduvirkjunar (tilraunar÷­ II), en ■ar voru stofnarnir ekki nema 10 talsins. ┴rlegar ni­urst÷­ur Ý ■essari tilraunar÷­ hafa birst Ý ßfangaskřrslum Rannsˇknastofnunar landb˙na­arins til Landsvirkjunar (┴slaug Helgadˇttir o.fl., 1983; ┴slaug Helgadˇttir og Ůorsteinn Tˇmasson, 1984a,1985; ┴slaug Helgadˇttir, 1986; ┴slaug Helgadˇttir og Snorri Baldursson, 1987). Einnig var ger­ grein fyrir ni­urst÷­um ˙r bß­um tilraunar÷­um ß Rß­unautafundi 1984 (┴slaug Helgadˇttir og Ůorsteinn Tˇmasson, 1984b), Ý ■essari grein ver­a dregnar saman ni­urst÷­ur ˙r ÷llum ■essum athugunum fram til ßrsins 1986.