Espie P 2002. Changes in vegetation states in grazed and ungrazed Mackenzie Basin grasslands
(C. rubra), and silver tussock (Poa cita). At each locality, three treatments were established: ambient sheep+rabbit grazing, rabbit grazing only, and no grazing. The mutivariate methods of classification and ordination were used on individual-quadrat cover data to define vegetation states and to ex...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
1990
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.376.1653 http://www.newzealandecology.org/nzje/free_issues/NZJEcol26_2_95.pdf |
| Summary: | (C. rubra), and silver tussock (Poa cita). At each locality, three treatments were established: ambient sheep+rabbit grazing, rabbit grazing only, and no grazing. The mutivariate methods of classification and ordination were used on individual-quadrat cover data to define vegetation states and to examine transitions between them over time. Vegetation states in quadrats already dominated by Hieracium pilosella (> 50 % cover) in 1990 showed little change in species composition regardless of grassland type and grazing treatment. In fescue tussock grassland, H. pilosella increased regardless of grazing treatment in states with low initial H. pilosella cover (< 5%), while the cover of Carex colensoi, Aira caryophyllea and Rumex acetosella decreased. In the single silver tussock locality, Poa cita decreased markedly in the ungrazed treatment as adventive species such as Dactylis glomerata and Echium vulgare increased. However, Poa cita also decreased, probably due to drought, in the grazed treatment. Snow tussock and red tussock grassland states were more stable than those in short tussock grasslands, but there was also a general trend towards increasing H. pilosella cover in intertussock vegetation regardless of treatment. However, at one snow tussock locality, transitions from H. piloselladominated to C. rigida-dominated states occurred in ungrazed quadrats, while the reverse occurred in grazed |
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