JC,3

BOTANY DIVISION DSIR.

REPORT

TUSSOCK (CHIONOCHLOA R~IGIDA AND C. RUBRA) COMHJN IT .1 ES AT SIX SI TES ALONG AN ENV I RCNr£NT Al GRADIENT ON THE OTAGO UPLANDS w.G. LEE BOTANY DIVISION USIR ' JUNE 1981 TUSSOCK (CHIONOCHLOA.RIGIDA AND C. RUBRA) COMMUNITIES AT SIX SITES ALONG AN ENVIRONMENTAL.GRADIENT

ON THE OTAGO UPLANDS

W.G. Lee

Botany Division, DSIR, Dunedin

JUNE 1981

Sunnnary

The structure and composition of tall tussock connnunities at six MAF trial sites on the Otago Uplands are described. , _f. rigida and Festuca novae-zelandiae, in various proportions, form the major cover, and most of the botanical differences between sites reflect differences in altitude, soil moisture or past management.

A species list is appended.

Plant Communities

tall tussock grasslands (narrow-leaved snow tussock and blue tussock) TUSSOCY. ( AND C. RUBRA) COMMUNITIES AT SIX SITES ALONG AN ENVIRONMENTAL GRADIENT ON THE OTAGO UPLANDS

W.G. Lee Botany Division, DSIR, F.O. Box 5306, Dunedin ( June 1981)

SID™ARY The structure and composition of tall tussock communities at six MAF trial sites on the Otago Uplands are described. Chionochloa rubra, C. rigida and Festuca novae-zelandiae, in various proportions, form the major cover, and most of the botanical differences between sites reflect differences in altitude, soil moisture or past management. INTRODUCTION This report was compiled at the request of Dr Feter Mcintosh, Invermay Agricultural Research Centre (MAF), Mosgiel, and describes tussock grassland communities at six sites on the Otago Uplands. The results of a soil survey to determine regional soil patterns and properties that might limit agricultural production on the Otago Uplands showed that climate, particularly rainfall, was the major environmental f'actor responsible f'or variations in soil properties (Mcintosh and Backholm 1981). Altitude was poorly correlated with soil chemistry. Wetter soils, predominantly on southern sites, were more acidic, with higher Al, Fe and Mn values than drier sites further north and inland. Following on from this work, Dr Mclnt'osh established six trial sites along the main environmental gradient for more intensive study of the fertiliser (FSCa) requirements for the successful establishment of Trifolium repens, T. pratense and Lotus pedunculatus amongst the snow tussocks. The sites are all on north-facing, slightly convex slopes with inclinations of 3-6°. Environmental parameters and selected soil properties are presented in Table 1 and illustrate the general trends discussed above, especially for soil pH and acidity related properties, (exact location of sites can be obtained from Dr Mcintosh). METHODS An area of similar size, slope and soil features adjoining the fenced experimental sites was sampled using the Scott height frequency method (Scott 1965). At one hundred points located at 0.5 m intervals along a tape, the TABLE 1: Experimental Site Characteristics.

I II III IV Y. VI

Altitude (m) .1160 llOO 1040 855 101Q 760

Rainfall (mm) 1100 .lQOO_ 755 630 630 470

Soil: Olsen P 7 3 ll 10.- 16 8 P retention (%}_ 52 57 .51 SQ 40 34 pH 4.4 4.6 4.6 4.8 s.Q 5.2 (ppm} 10 5 6 6 9 3 so4 Al4 in 0.1 m CaC1 (ppm) 77 70 60 52 SQ 2 20 SITE I

0 •0 0 "D c .... 0 ..... fj ... 0 . .. 0 u .. ... u •. .... E 0 Ii 0 ~:a :> Ii t: .... ::i c :> .... c c.. ...-3 ~ "". "". "".

SITE 11 "D...... J:> ""., ...... , :> •... "D .J:> ~ :z: ., Ill "-. . "- .

SITE Ill

SITE IV

> 0 c. ., ....

SITE V

SITE VI

Fig. 1 Diagrammatic representation of height frequency values . for species with a total height frequency above 10. Species are listed alphabetically and only named (i.e. first three letters of the binomial) at the first'f~t which they occur. They can be identified at subsequent sites by the shading. Width of the vertical scale indicat~s a frequency of 10% along the horiz­ ontal axis. TABLE 2: Cumulative Height Frequency Values for Individual Species at each site. + denotes species present but not recorded in any quadrat.

Site 1 II III IV v VI

Acaena anserinifolia + + A. caesiiglauca + + + Aciphylla aurea 2 71 + 2 tenuis 3 33 16 4 Anisotome aromatics 47 61 13 1 + 29 A. flexuosa + Anthoranthum odoratum 2 234 328 144 116 162 Astelia linearis 26 Bulbinella angustifolia 1 Carex breviculmis 1 3 C. colensoi 99 14 Carpha alpina 13 Cassinia vauvilliersii + Celmisia gracilenta 12 5 10 31 10 c. lyallii + c. prorepens 1 15 + c. sessiliflora 7 Cerastium holosteoides 2 Chionochloa rigida 746 9-63 326 572 261 + c. rubra 128 535 c. rigida .x rubra + + + Colobanthus strictus + 2 Coprosma cheesemanii 31 c. pumila 41 + 33 Craspedia uniflora + + 3 Crepis capillaris 1 Cyathodes colensoi 15 c. empetrifolia c. f raseri 17 84 J.O 32 39 Deyeuxia avenoides 6 + + D. setifolia + Donatia novae-zelandiae 1 Dracophyllum longifolium D. politum 62 Drapetes dieff enbachii 9 Epilobium alsinoides subsp alsinoides 6 4 3 8 E. hectori + 8 I II III IV v VI

Erythanthera pumila 6 Euphraeia zelandica 1 1 Festuca novae-zelandiae 37 130 42 Feetuca sp. + + Forstera sedifolia 1 Galium perpusillum 1 Gaultheria depressa var. depress a 20 14 1 6 Gentiana bellidifolia 1 Geranium microphyllum 17 11 10 1 6 Geum leiospermum 2 4 4 1 1 2 Haloragis depressa 1 Hebe odora 55 H. propinqua 18 + Helichrysum bellidioides 58 9 H. filicaule 19 3 10 Herpolirion novae-zelandiae 1 Hieracium pilosella 4 15 2 1 5 Hierochloe novae-zelandiae 32 Holcus lanatus + Hypericum j aponicum 3 + 1 H..ypochoeris radicata 57 84 56 19 107 Koeleria novo-zelandica + Lachnagrostis 'humili r' 15 Lagenifera pumila 22 + Leontodon autumnalis 2 1 1 Luzula ruf a 7 4 3 6 8 6 Lycopodium fastigiatum 17 15 50 Microtis unifolia 3 Mentha cunninghamii 2 Myr,sine nUI1DD.ularia 26 Nertera ciliata l Oreobolus pectinatus Oreomyrrhis colensoi + 2 Pentachondra pumila 31 2 + 19 Pernettya alpina 7 P. macrostigma 5 + 7 Pimelea oreophila 36 2 l 2 5 Plantago novae-zelandiae 2 Poa colensoi 161 123 158 61 166 37 Prasophyllum colensoi + + + I 11 Ill IV v VI

Pratia angulata 1 1 Ranunculus lappaceus 1 3 3 1 11 R. hirtus + 1 Raoulia glabra + + R. subsericea 17 33 4 33 14 Rumex acetosella 1 + 10 2 setifolia 6 76 R. thomsonii 7 Schoenus pauciflorus + + Scleranthus brockiei + l Senecio bellidioides 4 20 3 Stackhousia minima + Trifolium hybridum 4 T. pratense + 3 T. repens 3 l Uncinia filiformis + + U. rupestris + 9 Viola cunninghamii + 21 1 12 Wahlenbergia albomarginata 2 39 9 15 .12

Litter 118 139 78 94 90 70 Bryophyte 27 ·1 8 Rock .1 l Bare soil 5 12 9. 10 18 2.

presence of all species was recorded in 5 cm diameter cylindrical quadrats at 5 cm vertical increments above the ground. From the data height intercept histograms can be constructed giving a representative vertical cross section through the community. Summed frequencies for each species indirectly measure above ground biomass, although the precise relationship is probably different for every species and to date this has only been determined for Chionochloa rigida at one site in Canterbury using a modified height frequency procedure (Williams 1977). The Scott height frequency method was used by Bulloch (1973) to describe snow tussock communities in Black Rock Scientific Reserve on the Lammerlaw Range, and in several studies outside Otago (Williams 1975, 1977a, Scott 1977). RESULTS

The results are presented in two forms: major species are shown diagrammatically in Fig 1 • and a complete species list with cumulative height frequency values at each site, in Table 2. A brief description of the vegetation is given below: Site I: Narrow-leaved snow tussock (Chionochloa rigida) and blue tussock (Poa colensoi) are the physiognomic dominants, but apart from the small herb Anisotome aromatica, interstitial are mainly low growing shrubs (e.g. Dracophyllum politum, Hebe propingua, Pimelea oreophila, Cyathodes colensoi). Elsewhere in the catchment at a similar elevation, shrubland communities exist and the presence of Hebe odora seedlings at the site suggests a weakening of the resident tussock species. However, the amount of litter, tall tussock stature, completeness of intertussock cover and paucity of exotic species, taken together suggest that previous fire and grazing disturbances have not been great. The presence of the small bog Astelia (A. linearis) and occasional thick bryophyte mats reflect the hTgher rainfall at this site. Site II: This site has the greatest tussock cover with plants of Chionochloa rigida reaching ·1 .0 m tall. Shrub species are rare and it is therefore likely that the area has not been burnt for 5-10 years. Introduced species, particularly sweet vernal (Anthoxanthum odoratum) and catsear (Hypochaeris radicata) are well established in the tussock community and, combined, provide a greater cover than the indigenous inter­ tussock flora, the most abundant of which are Helichrysum bellidioides, Anisotome aromatica and Lycopodium fastigiatum. Remaining sites show more evidence of regular burning, oversowing and heavier grazing. The native component of total ~lant cover gradually diminishes, except for hard tussock {Festuca novae-zelandiae) and Raoulia subsericea, two species that are extremely tolerant of disturbance. Site III: Snow tussocks, only one third of the size of plants at the previous sites, blue tussock and sweet vernal co

and Raoulia subsericea. The small sub-shrub Cyathodes fraseri is also widespread, as is another short tussock grass, Rytidosperma setifolia. Site IV: This site occurs within a fire induced belt of Aciphylla aurea, which is rapidly increasing in abundance. The area has been burnt within the last three years, as the tussocks retain large amounts of dead leaf material. Brown­ top (Agrostis tenuis) and Lycopodium fastigiatum reach maximum abundance at this site, while sweet vernal and blue tussock are less common than at earlier sites. Sites IV, v and VI B.11 have red tussock (Chionochloa rubra) present, but at site IV, (although many tussocks have some of the sheath and leaf features of C. rubra), most leaf bases showing the multiple fracture-patterns characteristic of snow tussock. More pronounced red tussock with intact leaf sheaths is found at sites V and VI. Site V: Hard tussock is an important species here and shares dominance with blue tussock and sweet vernal, the Chionochloa spp being extremely sparse. Clovers (Trifolium repens, T. pratense, T. hybridum) are most successful at this site, inaicating that the area has probably been topdressed. Site VI: Red tussock, the only tall-tussock species at this site, is usually erect and appears to be less susceptible to grazing than snow tussock. Soil moisture is perhaps higher than the last two sites, as Coprosrna pumila, a typical of subalpine flush and bog communities, is quite common. Sweet vernal and catsear are again the major intertussock species with Pentachondra pumila and Cvathodes fraseri locally abundant.

DISCUSSION The sites encompass three grassland communities - Chionochloa rigida grassland (I-III), Chionochloa rigida - Festuca novae­ zelandiae grassland (IV & V), Chionochloa rubra grassland (VI). All communities show some deterioration as a result of grazing, burning, and oversowing. The tall tussock comD1unities are however remarkably resilient and the only exotics able to enter undisturbed vegetation ·are sweet vernal and catsear. Both clover and brown.top appear to require fertiliser assistance, at least on these soils. Pastural management on the eastern Otago uplands frequently results in scrub and fescue tussock replacing the depleted snow tussock cover (Mark 1955, Bulloch 1973). There is no evidence at these sites, apart from site I, of a widespread invasion of shrub species into burnt or grazed grasslands. Mark (1955) found that on warm aspects, and areas subjected to low stock numbers and irregular burning, shrub dominance was reduced, which would explain the predominance of a tall-tussock cover here. Replacement of tall-tussocks by fescue is well known but fescue is unlikely to become widespread above its present upper limit at these sites (1010 m). 4.

Red tussock reaches greatest abundance 1n lowland, swampy situations though it can occupy gleyed, poorly drained soils up to 1200 m in Otago. On the Otago Uplands red tussock is most common in small depressions and valley basins, but at site IV and V it is growing on non-gleyed, relatively free draining soils .. Connor and Macrae (1969) noticed that in Canterbury red tussock appears to cope with a variety of soil conditions and O'Connor et al. (1966) have demonstrated experimentally that this species-rias perhaps a wider edaphic tolerance than any of the other Chionochloa spp in eastern South Island areas. Using complex statistical procedures, Scott (1977) showed that on Mt Ruapehu, red tussock is most abundant on soils with high potassium levels. The concentration and yields of most major nutrients are lower in red tussock foliage than other tall tussock species on the same soils in eastern South Island (Williams et al. 1978). However more detailed information on red tusso"CK-snow tussock distribution on the eastern Otago Uplands is necessary before these studies can be usefully applied. Ecologically worthwhile inforniation would be gained from recording the tussock vegetation at the 71 sites for which soil chemical information is now available (Mcintosh and Backholm 1981), before agriculture completely alters the original grassland composition. ·Montane tussock grassland communities are under­ represented in the Otago reserve system and the eastern Otago Uplands provide perhaps the last opportunity to obtain adequate reserves of these threatened tall-tussock communities. It is therefore important that some consideration of reserves should be given prior to commitment of the total area to agriculture.

REFERENCES

Bulloch, B.T. 1973: A low altitude snow tussock reserve at Black Rock, Eastern Otago. Proceedings of the N.Z. Ecological Society 20: 41-47. Connor, H.E.: Macrae, A.H. 1969: Montane and subalpine tussock grasslands in Canterbury·. In Knox, S .A. (Ed.) "The Natural History of Canterbury". A.H. and A.W. Reed, Wellington, pp 167-204. Mark, A.F. 1955: Grassland and shrubland on Maungatua, Otago. N.Z. Journal of Science and Technology A37: 349-66. Mcintosh, P.D.: Backholm, G. 1981: A Reconnaissance Soil Survey of the Otago Uplands. MAF Technical Report No • 10. 4 9 pp • -

O'Connor, K.F.: Connor, H.E.: Molloy, B.P.J~ 1972: Response of four Chionochloa and two introduced grasses to soil amendment. N.Z. Journal of Botany 10: 205-24. 1965: A height frequency method for sampling tussock and shrub vegetation. N.Z. Journal of Botany 3: 252-60. 5.

Scott, D. 1977: Plant ecology above timber line on Mt Ruapehu, North Island, . I. Site factors and plant frequency. N.Z. Journal of Botany 15: 255-94. Williams, F.A. 1975: Studies of the tall-tussock (Chionochloa) vegetation soil systems of the southern Tararua Range, New Zealand. 2. The vegetation/soil relationships. _ N.Z. Journal of Botany 13: 269-303. 1977: Growth, biomass and net productivity of tall-tussock (Chionochloa) grasslands, Canterbury, New Zealand. N.Z. Journal of Botany 15: 399-442. Williams, P.A.: Mugambi, S.: Nes, P.: O'Connor, X.F.1978 Macro-element composition of tall-tussocks (Chionochloa) in the South Island, New Zealand, and their relationship with soil chemical properties. N.Z. Journal of Botany 16: 479-98.