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Age‐states, population structure, and seedling regeneration of Chionochloa pallens in Canterbury alpine grasslands, New Zealand
Author(s) -
Rose Alan B.,
Platt Kevin H.
Publication year - 1990
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.2307/3236058
Subject(s) - tussock , seedling , population , biology , canopy , ecology , juvenile , grassland , vegetation (pathology) , microsite , basal area , herbaceous plant , agronomy , medicine , demography , pathology , sociology
. Age‐states, population structure, and seedling regeneration of the grass Chionochloa pallens were investigated in eight alpine grassland stands representing the range of canopy cover (ca. 5–75 %) and basal area (112 ‐ 3889 m 2 /ha ‐1 ) in the headwaters of the Avoca catchment, Canterbury, New Zealand. In open‐canopy stands (< 50 % canopy cover, < 2000 m 2 /ha ‐1 basal area) C. pallens individuals were clearly distinguishable. Rela‐tionshipsbetweenbasal diameter, number of tillers, height, and % crown death suggested four putative age‐states: ‘seedlings‘, ‘juvenile tussocks’, ‘mature tussocks’ and ‘senescent tussocks’. Four types of population structure were identified depending onthe proportions of seedlings and juvenile and mature tussocks. C. pallens seedlings were present in seven stands at densities ranging from 0.6 to 123.4 / m 2 . They were most frequent on microsites protected from frost‐heave by short herbaceous vegetation or litter, but with little competition from taller vegetation. Differences in seedling densities between stands partly reflected the proximity and abundance of seed sources and degree of protection from frost‐heave. C. pallens population structures appear to be influenced by the frequency and magnitude of geomorphic disturbances and browsing by introduced animals.