Worldwide declines in bird numbers have recently renewed interest in how well bird-plant mutualisms are functioning. In New Zealand, it has been argued that bird pollination was relatively unimportant and bird- pollination failure was unlikely to threaten any New Zealand plants, whereas dispersal mutualisms were widespread and in some cases potentially at risk because of reliance on a single large frugivore, the kereru (Hemiphaga novaeseelandiae). Work since 1989, however, has changed that assessment. Smaller individual fruits of most plant species can be dispersed by mid-sized birds such as tui (Prosthemadera novaezelandiae) because both fruits and birds vary in size within a species. Only one species (Beilschmiedia tarairi) has no individual fruits small enough for this to occur. Germination of 19 fleshy-fruited species, including most species with fruits >8 mm diameter, does not depend on birds removing the fruit pulp. The few studies of fruit removal rates mostly (7 out of 10) show good dispersal quantity. So dispersal is less at risk than once thought. In contrast, there is now evidence for widespread pollen limitation in species with ornithophilous flowers. Tests on 10 of the 29 known native ornithophilous-flowered species found that in 8 cases seed production was reduced by at least one-third, and the pollen limitation indices overall were significantly higher than the global average. Birds also frequently visit flowers of many other smaller-flowered native species, and excluding birds significantly reduced seed set in the three species tested. So pollination is more at risk than once thought. Finally, analyses of both species numbers and total woody basal area show that dependence on bird pollination is unexpectedly high. Birds have been recorded visiting the flowers of 85 native species, representing 5% of the total seed-plant flora (compared with 12% of those with fleshy fruit) and 30% of the tree flora (compared with 59% with fleshy fruit). A higher percentage of New Zealand forest basal area has bird-visited flowers (37% of basal area nationally) than fleshy fruit (31%). Thus, bird pollination is more important in New Zealand than was realised, partly because birds visit many flowers that do not have classic "ornithophilous" flower morphology .

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Mutualisms with the wreckage of an avifauna: the status of bird pollination and fruit- dispersal in New Zealand

Seventeen exclosures were built by the New Zealand Forest Service within Urewera forests over the period 1961-68 to exclude ungulates. Forest structure and species composition inside and outside these exclosures were compared in 1980-81. Some relatively shade tolerant species such as the fern Asplenium bulbiferum, the liane Ripogonum scandens, the sub-canopy shrubs Geniostoma ligustrifolium and Coprosma australis and the canopy species Beilschmiedia tawa were less abundant in certain tiers outside the exclosures than inside. By contrast, only a few species were more abundant outside then inside the exclosures. These included the unpalatable shrub Pseudowintera colorata, turf-forming Uncinia species and Cardamine debilis. Overall density and species richness for small diametered trees and for the sapling tier were lower outside the exclosures than inside. Despite the large reduction in ungulate numbers throughout Urewera forests these introduced browsing animals, particularly deer, still affect the structure and composition of most forest types.

/pdf/effects-of-ungulates-on-structure-and-species-composition-in-5amaro412k.pdf

Effects of ungulates on structure and species composition in the Urewera forests as shown by exclosures

Strategies to estimate national forest carbon stocks from inventory data: the 1990 New Zealand baseline

Lauraceae from rainforest surrounding an early Miocene maar lake, Otago, southern New Zealand

The composition and structure of forest at Pureora, overthrown and buried by pumiceous tephra during the c. AD 130 Taupo eruption, are deduced from identification of plant macrofossils. A tall, dense podocarp forest was dominated by rimu (Dacrydium cupressinum) and tanekaha (Phyllocladus trichomanoides), with occasional matai (Prumnopitys taxifolia) , miro (Prumnopitys ferruginea), kahikatea (Dacrycarpus dacrydioides) and totara (Podocarpus totara). Understorey plants included toro (Myrsine salicina), horopito (Pseudowintera colorata), Neomyrtus pedunculata, Metrosideros diffusa, crown fern (Blechnum discolor) and Leptopteris superba. Poorly drained sites were dominated by kahikatea, rimu, tanekaha, Astelia grandis, Gahnia xanthocarpa and kiekie (Freycinetia baueriana ssp. banksil) with rare bog pine (Halocarpus bidwillil) and kaikawaka (Libocedrus bidwillil)' The classification and ordination techniques applied indicated that the forest was basically of one type with minor variations reflecting ...

https://www.tandfonline.com/doi/pdf/10.1080/03036758.1988.10426466

Composition and structure of forest overwhelmed at Pureora, central North Island, New Zealand, during the Taupo eruption (c. AD 130)

Morphological and anatomical descriptions of Beilschmiedia tawa are given together with information relevant to its ecology, a distribution map based on its presence or absence in grid squares, and bibliographic references to other informaion. B. tawa is one of the main canopy-forming trees in the lowland and low hill forests of the North Island and is also one of the main merchantable hardwoods. It has a good capacity to regenerate in shade or small canopy gaps, but is sensitive to exposure, tending to deteriorate in intensively logged forests.

A. E. Beveridge

Papers

Biological flora of New Zealand 9. Beilschmiedia tawa(A. Cunn.) Benth. et Hook. F. ex Kirk (Lauraceae) Tawa