Alectryon excelsus

Abstract: Seed predation trials were conducted for 11 large‐seeded species native to New Zealand in secondary forest. The species used were: Alectryon excelsus, Beilschmiedia tawa, Coprosma grandifolia, Corynocarpus laevigatus, Hedycarya arborea, Myoporum laetum, Nestegis cunninghamii, Prumnopitys ferruginea, Prumnopitys taxifolia, Rhopalostylis sapida, and Ripogonum scandens. Seed removal was monitored for 15 days for 160 seeds of each species, placed in piles of 5 seeds in each of 4 treatments at each of 8 sites in the Karori Wildlife Sanctuary, Wellington, in 1998. Removal of depulped seeds from treatments to which all species had access ranged from 3.8% to 23.8%, with a mean of 9.8%. No seeds were removed from the treatment that excluded all vertebrates. Presence of flesh on the seeds significantly increased seed removal rates in the three species tested with and without flesh. No relationship was found between seed removal and seed size, seed mass, or the proportion of the seed mass that was contribut...

Abstract: Seed germination of woody species was studied in treefall gaps in NewZealand to assess how environmental heterogeneity affects regeneration fromseed. Gaps were created in a relictual Pinus radiataplantation destined for restoration to native forest. Seeds of the nativespecies Alectryon excelsus, Macropiperexcelsum, and Fuchsia excorticata, and theinvasive alien species Cytisus scoparius andBerberis darwinii were sown in sites differing inexposure,with and without 3 cm of pine litter. Litter promoted germinationof Alectryon and Macropiper,independent of site. Without litter, percent germination ofMacropiper was negatively correlated with percent open skyoverhead. Germination of Fuchsia was significantly higherin treefall gaps than in the forest understory, with litter having littleeffect. Cytisus germinated most successfully in sitesexposed to direct solar radiation, with or without litter. Percent germinationof Berberis was high in all sites, and was consistentlypromoted by litter. Glasshouse trials for each species showed the same effectsof litter cover as found in the field. These results suggest thatmicroenvironmental heterogeneity can be an important influence on the speciescomposition of regenerating vegetation within and around treefall gaps.

Abstract: Vegetation was sampled in kahikatea (Dacrycarpus dacrydioides)-dominant forest fragments having different recovery periods since grazing ceased in the Waikato region, North Island, New Zealand. Changes in vegetation were modeled against recovery periods ranging from 0-74 y and in relation to position within fragment (edge or interior). Indigenous plant species richness increased and adventive plant species (mostly pasture herbs) richness declined with increasing recovery period; small tree and sapling density and seedling ground cover increased. Fragment edges had higher adventive species richness, lower basal area, more established seedlings, lower litter cover and higher grass ground cover, than interior plots. Some indigenous species (e.g. Laurelia novaezealandiae and Myrsine australis) increased with recovery period while some adventive species (e.g. Solanum pseudocapsicum) declined. The relative basal area of Alectryon excelsus increased significantly with recovery period at edges, and that of Melicytus ramiflorus everywhere. Twenty years represents a turning point in the recovery period, with the end of the loss phase of adventive pasture species, the start of the re-establishment phase of indigenous ground layer and understorey species, and significant recovery of population structures of major species. In relatively non-weedy rural environments, retirement from grazing may be sufficient to ensure a return to near-natural states in 40-50 y.

Abstract: The effect of the 1987-89 drought on the native vegetation of bush remnants on Banks Peninsula was examined using measurements of water potentials and growth, and ordination of species composition. Marked individuals of five species (Alectryon excelsus, Helichrysum aggregatum, Kunzea ericoides, Melicytus ramiflorus, and Podocarpus totara) were studied in detail in Ahuriri Valley. The drought was severe, whether judged by visual appearance (extensive wilting and leaf fall), water potentials (≤-7.1 MPa), or survival (three of the marked individuals died). Water potentials were initially very low, but most plants eventually recovered. One K. ericoides plant had all five samples below -7 MPa in December 1988 yet still survived. Growth was reduced, however, with narrower growth rings in A. excelsus and shorter leaves in P. totara during the drought. The first ordination axis of vegetation samples from the reserve matched the rainfall/moisture gradient, suggesting that water availability is important i...