NOKTH CAPE QUADRATS by W. J. Rae* SUMMARY

Transcription

1 Tone (19/0) 16: NOKTH CAPE QUADRATS 1969 by W. J. Rae* SUMMARY Vegetation maps of quadrats established by ravatt (1966) at Kerr Pt. in the North Cape Scenic Reserve are presented. Percentage cover of plants present in the quadrats was estimated and is provided in tables and figures. Changes which have occurred since previous surveys are discussed. INTRODUCTION In December 1965 ravatt set up quadrats in the North Cape Scenic Reserve near Kerr Pt. to assess any changes occurring in the vegetation. Cleared quadrats were established to determine the recolonization pattern of bared areas in the Plateau Scrub. (Area at Xj). A quadrat was set up in a rush association on a ridge which had been recently burnt. (Area at X 2). At this time the vegetation in the uncleared quadrats at Xj was mapped and the numbers and dominance of each species present at X 2 estimated (ravatt 1966). In January 1967 Johnstone mapped the vegetation in the cleared quadrats at Xj and reestimated the vegetation in the quadrat at X 2. In August 1969, during an Auckland University Field Club scientific camp, the area was revisited and the quadrats inspected. The present paper deals with observations made and data compiled from these quadrats. METHOD Mapping of the vegetation was carried out after the method of ravatt (1966) and Johnstone (1967). In addition, percentage cover was estimated by dropping a needle at points taken at regular intervals along lines running across the quadrats, and recording the first hit at each point. The number of hits per species expressed as a percentage of the total number of points taken is an estimate of the cover contributed by each particular species. Other species present but not hit were also recorded. Department of Botany, University of Auckland.

2 54 RESULTS AND DISCUSSION Hie Quadrat at \\ (ravatt,1966) Sited in the Plateau Scrub Results Figures 1 and 2 are the vegetation maps of the uncleared quadrats which measured 6 ft. x. 6 ft. Figures 3 and 4 are the vegetation maps of the cleared quadrats which measure 4 ft. x. 4 ft. These maps can be compared directly with those of ravatt (1966) and Johnstone (1967). Percentage cover and species present for these quadrats are given in Table 1. Points for the analysis were taken every six inches along lines which were six inches apart for the cleared quadrats, giving 81 points, and twelve inches apart for the uncleared quadrats, giving 91 points. KEY FOR FIS. 1, 2, 3 & 4 Cassinia amoena Ca Cyathodes parviflora Cp C. fraseri Cy Phormium tenax F naphalium luteo-album Hypochaeris radicata H Haloragis cartilaginca He Hebe ligustrifolia He Haloragis procumbens Lepidosperma laterale L Lobelia anceps La Leptospermum scoparium melia prostratu Poa annua Po Pomaderris prunifoliii var. edgerleyi P. phylicifolia Pp var. ericifolia Pteridium aquilinum Pt var. esculcntum Tkelymitra longi/olia T

3 Unfenced Fenced FIS I and 2: Vegetation maps of the uncleared quadrats which can be compared directly to those of ravatt (1966). Each quadrat measures 6 ft by 6 ft.

4 Po Po Unfenced Pt > Pt U p, Po * Ho ft HP i r,. s * * jy Figure 3 P. H, L * L * ^Pt T P l Pt TT Pt " Po r p Ca LS H P P. u H r HPPI Cy H ( Pt T Cy ' PI U n R T PI P m P t p r PL p P t p rm Km ' Pt I pi Br.,11*. Pt Pp r "> L Co p Po Fen ced Co Ca * * P+ P > CyCv * Ur H, ' Figure LS Po ft Pb * P~ P L S P. p, * P - ii ^. p m T _ P» Cj ft, r Po P " P UP«H P ft Pt P m ' H Mf P oho H P i P l P o FIS 3 and 4: Vegetation maps of the cleared quadrats Johnstone (1967). Each quadrat measures 4 ft by 4 ft. which can be compared directly to those of

5 57 TABLE I: Percentage cover of species and species present in quadrats located in the plateau scrub. Bare ground Pteridium var. aquilinum csculentum UNCLEARED PERCENTAE COVER CLEARED Unfenced Fenced Unfenced Fenced Haloragis procumbens Poa annua Pomadcrris var. edgerleyi prunifolia Lepidosperma laterale Hebe ligustrifolia Cassinia amoena Leptospermum scoparium Cyathodes fraseri Cyathodes parviflora 1.00 melia prostrata naphalium lutco-album Thelymitra longifolia Cassytha paniculata Hypochaeris radicata + + Haloragis cartilaginea + Phormium tenax + Lobelia anceps + Pomaderris phylicifolia var. ericifolia + + Species present but not hit. Discussion The plateau scrub in this area seems to have changed little from that described by ravatt (1966). The differences in the uncleared quadrats are mainly fluctuations in size of Hebe ligustrifolia and Cassinia amoena bushes and the increase in size of some clumps of Lepidosperma laterale. Plants labelled Cladium junceum in figures 2 and 3 by ravatt (1966) are in identical positions to those now occupied by clumps of Lepidosperma laterale, no Cladium junceum being observed in these quadrats by the present author. The fenced quadrat now contains a young plant of Phormium tenax with leaves approximately 18 inches high. In the cleared quadrats notable and important entries since the survey by Johnstone (1967) are: Haloragis procumbens, Cassinia amoena,

6 58 Cassytha paniculata in both quadrats, Haloragis cartilaginea, Lepidosperma laterale in the fenced quadrat, and Leptospermum scoparium in the unfenced quadrat. Any differences in percentage cover of the species between fenced and unfenced quadrats is probably no greater than the variation which could be expected using the point analysis technique. Other features shown by data in Table I are as follows: The cleared quadrats still have about 80 per cent bare ground after three and a half years. Pteridium aquilinum var. esculentum provides a similar amount of cover in both the cleared and uncleared quadrats probably indicating that the rhizomes were not removed on clearing and that there has been little difference in their subsequent growth. The vegetation in the area of these quadrats is a low scrub less than 18 inches high dominated by Cassinia amoena and Hebe ligustrifolia with a background mat of Leptospermum scoparium 6 to 12 inches high. The extent of this mat cannot be shown adequately with vegetation maps, but with the point analysis technique used, it was found to provide 60 to 65 percent of the ground cover. Plants with prostrate habits such as Haloragis procumbens and Pomaderris prunifolia var. edgerleyi are among the first colonists in the cleared quadrats, forming the major proportion of the total plant cover. Species forming a major part of the cover in the uncleared quadrats are now present in measurable numbers in the cleared quadrats. By comparing the present survey with those by ravatt (1966) and Johnstone (1967) it is evident that there are minor seasonal differences. In this survey Anagalis arvensis, Erichtites atkinsonii, Odontites viscosa and Dichondra repens were not recorded. A few stunted plants of Hypochaeris radicata were found, and most plants of Poa annua were very stunted. This seasonal difference is not considered to be a complicating one as recording establishment of perennial herbs and shrubs is the long term objective in this study. Further analysis of the above type will enable changes in the composition of the quadrat to be followed more readily than is possible

7 59 TABLE 2: Percentage cover of species found in the 'rush' quadrat. Percentage Cover Schoenus brevifolius Leptospermum scoparium Poa annua Cyathodes fraseri 3.01 Pomaderris phylicifolia var. ericifolia 1.82 Cassinia amoena 1.82 Lepidosperma laterale 0.60 Pomaderris kumeraho 0.60 Pteridium aquilinum var. esculentum 0.60 Bare ground by mapping. It will be interesting to see how closely the percentage cover values of species in the cleared quadrats approach those of species in the uncleared quadrats as the area becomes colonized. The quadrat at X 2 (ravatt, 1966) Sited in Rushes Results The percentage cover of each species in this quadrat, which measures 12 ft. x. 12 ft. was estimated. Points were taken every 12 inches along lines 12 inches apart, giving 169 points. Table 2 shows the results of this analysis. Other species present but not hit were Pomaderris prunifolia var. edgerteyi, Cassytha paniculata, and Drosera auriculata. Discussion One very important correction to be made is that the dominant species in this quadrat, providing 46 per cent of the cover, is Schoenus brevifolius not Cladium junceum as identified by ravatt (1966) and Johnstone (1967). ravatt (1966) described the dominant species in this quadrat as "Cladium junceum... not in clumps but evenly spread throughout." The habit, general morphology, and stem anatomy are those of Schoenus brevifolius. Schoenus brevifolius still dominates numerically and in height.

8 60 As a count of the other main species was not carried out no further direct comparison with earlier surveys can be made. However, one important plant, new to this quadrat, is Cassinia amoena which is a co-dominant in the area at The low value for Poa annua, which was reported by ravatt (1966) to be numerically co-dominant with Schoenus, is almost certainly due to a seasonal variation. CONCLUSION There is little evidence from the fenced ana unfenced quadrats to suggest that large grazing animals are active in this northern area of the North Cape Scenic Reserve. Regeneration of the bared areas is slow with 80 per cent of the area still bare ground. The estimation of percentage cover for all the quadrats has provided a quantitative basis for comparison with future investigations in the area. ACKNOWL EDEMENTS I wish to thank Miss Jean Ferguson and Mr. C. Quilter for assistance in the field, and Misses Elizabeth Dickson and Rosalie Lambert and Mr. J. Braggins for help with the identification of certain species. REFERENCES ALLAN, H. H BEEVER, R. E., 1967 JANE,. T. CHEESEMAN, T. F "Flora of New Zealand". Volume 1. ovt. Printer, Wellington. Additional Plant Records From North Cape. Tane 13: "Manual of the New Zealand Flora". ovt. Printer, Wellington. RAVATT, D. J Establishment of Permanent Quadrats in Plateau Scrub at North Cape. Tane 12: JOHNSTONE, I. M A Report on the Permanent Quadrats at North Cape. Tane 13: WHEELER, J. M The Vegetation of the North Cape Area. Tone 9:63-83.