Long-term retirement of New Zealand snow tussock rangeland: effects on canopy structure, hawkweed (Hieracium spp.) invasion and plant diversity

Figures & data

Figure 1  Obelisk Station showing locations of the four plot sites (•) on the Old Man Range and the Station boundary. Site map prepared by P. Espie; sourced from NZMS 260, G42 – Alexandra. Crown Copyright Reserved.

Figure 2  View east in May 2007 across two of the 1220–1230 m plots on the Old Man Range: A–A marks the fire break created in 1961; B is the area protected from burning in 1961 and unburnt since at least 1945; C is the 22×22m exclosure established in 1960 and also unburnt since at least 1945; D is the adjacent 1220 m grazed plot, beyond the exclosure; E is the area burnt in 1961 and again in 1992 (note the sparse snow tussock cover and numerous smaller tussocks of Festuca matthewsii); F is the 1230 m 20×10 m plot in the same area, which is located to the lower left foreground from the corner of the stake next to the person.

Table 1  Mean values for density, per cent cover and frequency of Hieracium lepidulum in 45–121 subplots of 2×2 m in six plots on the Old Man Range, with relevant details of stock grazing and burning as indicated.

Plot alt. (m) and treatments	N	Density	SE	Sig.	% Cover	SE	Sig.	Frequency (%)
910 m Ungrazed Burnt 1992	121	34.11	7.08	***	5.64	0.95	***	93
910 m Grazed Burnt 1992	100	1.26	0.30		0.15	0.04		48
1220 m Ungrazed Unburnt since c. 1945	121	0.34	0.08	n.s.	0.07	0.02	n.s.	19
1220 m Grazed Unburnt since c. 1945	100	0.28	0.05		0.03	0.01		25
1230 m Ungrazed Burnt 1961/1964	45	8.16	2.82	***	1.67	2.82	**	71
1230 m Grazed Burnt 1961	50	0.68	0.13		0.06	0.02		44
1230 m Grazed Burnt 1961/1992	50	0.66	0.18		0.18	0.03		34
Note: Standard errors (SE) of the means are presented. Significance values are based on t-tests or analysis of variance, and the overall error: ***p<0.001; **p<0.01. Values for frequency were significantly different (p<0.001) between the seven plots by a chi-squared test. n.s., not significant.

Figure 3  Diagrammatic representation of height–frequency values (see scales at top centre) for the tussock species (Chionochloa rigida, Festuca novae-zelandiae, Festuca matthewsii) plus speargrass (Aciphylla aurea) and hawkweed (Hieracium pilosella and H. praealtum combined, as Hier. pilo.) at seven sites on the Old Man Range. The altitude and differential burning (UB=unburnt; B=burnt during the year(s) specified) and grazing (UG=ungrazed; G=grazed) treatments are shown for each site. The total above-ground biomass index for each species is shown at the base of its kite diagram.

Figure 4  Dendrogram from cluster analysis of species composition in the six study plots on the Old Man Range. Groups of plots with significantly dissimilar species composition (p<0.05), are shown in bold; the remainder are non-significantly dissimilar Plots are identified by: altitude (m); unburned (UB) or burned (B) with year(s); and grazed (G) or ungrazed (UG).

Table 2  List of vascular species (39 native; 12 exotic) and their estimated cover in seven plots at three altitudes (910 m, 1220 m and 1230 m) on the Old Man Range, representing different burning (B) and grazing histories since 1945, as indicated.

Plant species	910 m B1992 Ungrazed	910 m B1992 Grazed	1220 m Unburnt Ungrazed	1220 m Unburnt Grazed	1230 m B'61/'64 Ungrazed	1230 m B'61 Grazed	1230 m B'61/'92 Grazed
Acaena caesiiglauca	0	0	<1	<1	0	0	0
Aciphylla aurea	1	<1	8	1	12	1	2
*Agrostis capillaris	10	10	2	2	1	2	1
Anisotome aromatica	<1	<1	0	0	0	0	0
Anisotome flexuosa	0	0	<1	0	<1	<1	0
*Anthoxanthum odoratum	2	2	<1	<1	<1	<1	1
Blechnum penna-marina	<1	0	0	0	0	0	0
Brachyglottis bellidioides	<1	0	0	0	0	0	0
Carex wakatipu	0	0	<1	<1	<1	<1	<1
Celmisia gracilenta	<1	<1	<1	<1	<1	<1	<1
Celmisia lyallii	0	0	6	0	<1	0	0
Celmisia sessiliflora	0	0	<1	0	0	0	0
Celmisia viscosa	0	0	<1	0	0	<1	0
*Cerastium fontanum	<1	<1	0	0	0	0	0
Chionochloa rigida	80	80	70	70	55	45	5
Chionochloa rigida seedlings	0	0	<1	<1	<1	<1	0
Coprosma cheesemanii	<1	0	0	0	0	0	0
Craspedia uniflora	0	0	<1	<1	<1	<1	0
Deyeuxia avenoides	<1	<1	<1	<1	<1	<1	0
Dichelachne crinita	0	<1	0	0	0	0	0
Dracophyllum muscoides	0	0	<1	0	0	<1	0
Dracophyllum uniflorum	0	0	<1	0	<1	0	0
Elymus solandri	0	<1	0	0	0	0	0
Epilobium alsinoides	<1	0	<1	<1	1	<1	0
Festuca matthewsii	0	0	<1	<1	1	2	15
Festuca novae-zelandiae	1	1	0	0	0	0	0
Gaultheria depressa	<1	0	1	1	<1	1	0
Gaultheria macrostigma	<1	0	0	0	0	0	0
Gentianella bellidifolia	0	0	3	1	<1	<1	0
Geranium microphyllum	<1	0	0	0	0	0	0
Helichrysum filicaule	<1	<1	0	0	0	<1	0
*Hieracium lepidulum	2	<1	<1	<1	1	<1	<1
*Hieracium pilosella	0	0	<1	<1	<1	<1	3
*Hieracium praealtum	0	0	0	0	0	0	<1
*Holcus lanatus	2	5	0	0	0	0	0
*Hypochaeris radicata	1	<1	2	1	1	<1	2
Lagenifera cuneata	0	0	<1	<1	1	<1	1
Leucopogon fraseri	1	<1	<1	<1	2	3	1
*Lotus pedunculatus.	2	0	0	0	0	0	0
Luzula rufa	<1	<1	<1	<1	<1	<1	1
Lycopodium fastigiatum	<1	<1	<1	<1	<1	<1	0
Ozothamnus leptophyllus	0	0	<1	0	<1	<1	0
Pentachondra pumila	0	0	<1	0	1	0	0
Poa colensoi	1	3	2	1	2	2	28
Phyllachne colensoi	0	0	<1	0	0	0	0
Ranunculus multiscapus	<1	1	<1	<1	1	<1	<1
Raoulia subsericea	<1	<1	2	1	1	3	25
*Rumex acetosella	<1	<1	0	0	0	<1	2
Rytidosperma pumilum	0	0	0	<1	0	0	1
*Trifolium pratense	<1	0	0	0	0	0	0
*Trifolium repens	<1	<1	<1	<1	0	<1	<1
Uncinia fuscovaginata	0	0	<1	<1	1	<1	<1
Wahlenbergia albomarginata	<1	<1	<1	<1	<1	<1	<1
Viola cunninghamii	<1	<1	<1	<1	1	<1	<1
moss: Polytrichum juniperinum	<1	<1	<1	<1	<1	<1	<1
lichens	1	<1	1	1	2	1	0
Bare soil	0	0	0	4	0	<1	4
Dead	5	2	6	5	8	6	3
litter	6	2	10	10	10	10	1
rock	0	0	0	0	0	<1	2
Total native vascular species	2	1	3	2	2	25	1
Total exotic vascular species	10	8	6	6	5	7	8
Richness: Total vascular spp.	32	25	36	28	30	32	23
Diversity index: H′(log e )	1.456	1.285	1.713	1.161	1.726	1.816	2.076
Note: Values for total Richness and Diversity (Shannon Index) for each plot are also included. See text for details. An asterisk before the name denotes an exotic species.

Table 3  Results of a SIMPER analysis of dissimilarities: (a) between burnt and unburnt plots and (b) between ungrazed (fenced) and grazed (unfenced) plots (b: below) among seven plots at 910 m, 1220 m and 1230 m on the Old Man Range.

Plant species	Mean abundance	Mean abundance	Percentage contribution	Cumulative percentage contribution
a. Mean dissimilarity between burnt and unburnt plots=38.17%
	Burnt	Unburnt
Chionochloa rigida	6.71	7.71	8.33	8.33
Poa colensoi	2.67	1.31	5.40	13.73
Raoulia subsericea	2.14	1.29	5.14	18.86
Festuca matthewsii	1.29	0.96	5.05	23.92
Litter	1.62	3.16	4.99	28.91
*Agrostis capillaris	2.44	1.31	4.32	33.22
*Holcus lanatus	1.22	0.00	3.89	37.12
Gentianella bellidifolia	0.00	1.04	3.06	40.17
Aciphylla aurea	1.04	2.07	2.86	43.03
*Hieracium pilosella	0.58	0.71	2.59	45.62
Gaultheria depressa	0.24	0.93	2.34	47.96
Chionochloa rigida seedlings	0.00	0.71	2.24	50.21
b. Mean dissimilarity between ungrazed and grazed plots=23.96%
	Ungrazed	Grazed
Chionochloa rigida	8.24	6.56	8.18	8.18
Aciphylla aurea	2.43	1.03	7.47	15.65
bare soil	0.00	1.18	6.00	21.65
Celmisia lyallii	1.05	0.00	4.97	26.62
Poa colensoi	1.28	2.36	4.85	31.47
Raoulia subsericea	1.04	2.11	4.71	36.18
Festuca matthewsii	0.57	1.50	4.32	40.50
Pentachondra pumila	0.57	0.00	2.74	43.23
*Agrostis capillaris	1.86	1.75	2.46	45.70
*Lotus pedunculatus	0.47	0.00	2.39	48.09
Dracophyllum uniflorum	0.47	0.00	2.26	50.35
Note: Only species which contributed most to the first 50% of dissimilarities are shown. Exotic species are indicated with an asterisk.

Figure A1.1  One of three samples of Hieracium lepidulum collected from 1230 m Old Man Range, showing what was assumed to be two plants in the field (top), and which was confirmed with washing (bottom). Each of the two plants had a tightly interconnected root mass, but apparently functioned as separate individuals; no root grafts were seen.