white space
Page 6 of the DoC Critique written by Colin O'Donnell.

Summary & Recommendations


1.1 Principles: Impacts of logging on New Zealand wildlife

1.1.1.   Many of the forests in the North Westland beech area can easily be termed as significant habitats for indigenous fauna under the criteria of the RMA. The forests support significant populations of 24 indigenous forest birds including six nationally threatened and two regionally theatened species, two threatened bats and several threatened fish species.

(See comment 54) Birds such as the kaka, and long-tailed bats, have been declining steadily throughout the country, and all habitats where they occur should be considered key sites for their recovery. Therefore, ensuring the sustainability of these populations should be paramount when setting harvesting limits for sustainable forest management.

1.1.2   The BSM largely refers to the impacts on foraging habitats for birds.

(See comment 55) However, ensuring the sustainability of roosting and breeding sites is just as important. Maintenance of foraging habitat would be meaningless without protection of a viable number of preferred nesting, roosting or breeding sites - and vice versa.

1.1.3   A major premise of the mitigation programme being proposed by TWCL assumes that predators are the most important threat to wildlife communities. While habitat preservation without predator control would not sustain populations of threatened species, neither would predator control sustain wildlife populations without protection of critical roosting, breeding and foraging habitats. Management of threatened wildlife populations required an integrated management programme which incorporates control of pests and predators and maintenance of critical habitat.

1.1.4   "Avifauna remains one of the greatest unknowns in terms of the effects of any management" (BSM, p. 169). TWCL are using a new harvesting technique for North Westland forests,

(See comment 56) so obviously there are no data on its impact on wildlife. Therefore, at this stage we can only use predictive approaches to assessing potential impacts. However, the fact that a wide variety of historical harvesting techniques have all led to significant declines in numbers of threatened species serves as a warning of potential impacts.

(See comment 57) 1.1.5   We need to go some way towards predicting impacts at this stage (see below) but if the logging is to go ahead then a rigorous research-by-management approach needs to be adopted and specific logging prescriptions need to be changed as necessary if adverse impacts are detected. Studies of wildlife foraging, breeding and roosting preferences in red beech forest will improve predictions.

(See comment 58) 1.1.6 The MSMP, the document which should be specifically outlining mitigation procedures to reduce these effects, chooses not to acknowledge the New Zealand research or demonstrate how the impacts would be dealt with in New Zealand, but rather uses overseas studies. The assertion that logging increases diversity is misleading. Logging decreases the diversity of endemic, specialised and threatened species, while increasing diversity of edge-dwelling and introduced species.

1.2 Mitigation of impacts of harvesting on threatened bat species

1.2.1 Forests in North Westland support the

(See comment 58a) only significant populations

of the threatened South Island long-tailed bat known outside of the eastern Fiordland/Aspiring area.

1.2.2 While the BSM and MSMP reports note the presence of bats in TWCL forests they fail to address how harvesting regimes will

(See comment 59) mitigate effects on bat populations.

It is not appropriate to assume that measures proposed for forest birds will also assist bat populations

1.2.3 Specific surveys for short-tailed bats should be undertaken by TWCL using automatic bat detector units and mistnetting.

(See comment 60)1.2.4 Research from the Eglinton Valley in Fiordland suggests that the harvesting regimes proposed would be detrimental to these threatened species.

Sampling of trees available to long-tailed bats indicated that suitable trees were rare in the forest and were concentrated in lowland forests on river terraces and outwash fans on the valley floor. They selected trees > 80 cm DBH.

1.3 Beech tree harvesting rates and mitigating effects on wildlife

1.3.1 The most effective way to predict whether the harvest rates proposed (sic) is to compare those rates with the specific requirements of wildlife (in terms of sizes and ages of trees required for breeding and foraging) and then determine if sufficient trees remain through the harvesting cycle to allow for maintenance of critical wildlife populations in perpetuity.

1.3.2 This submission demonstrates (i) how the specific effects of the logging regimes proposed might be predicted; and (ii) that proposed harvesting rates in the Maruia working circle may remove significant amounts of wildlife habitat, particularly for threatened species (long-tailed bat, kaka, yellow-crowned parakeet).

1.3.3 One of the main predicted impacts of the harvesting regimes proposed would be the reduction in the number of older cavity-bearing trees. While the importance of cavities is disputed by TWCL

(See comment 61) there is a huge literature available on how limitation of cavity availability can influence the viability of wildlife populations.

(See comment 62)1.3.4 We predict that a minimum of 14 cavity-bearing trees/ha are required for threatened species

(long-tailed bat, kaka and yellow-crowned parakeet) for breeding and roosting (i.e. 83.5% of the 17 trees >80 cm DBH/ha present in the Maruia Working Circle). Thus there is a high probability that any trees > 80 cm DBH selected for harvesting would be trees required by these threatened species. Overall, the rate of felling these trees at 0.105 trees/ha/yr indicates a high minimum probability of removing 9.3% of preferred breeding trees/ha per 15 year rotation.

(See comment 63) Over 120 years (allowing for 15 years resting between each cycle), a minimum of 37% of preferred trees would be removed.

This is unlikely to be sustainable for wildlife in the long term given that

(See comment 64) trees take a minimum of 300 - 450 years to reach a size whereby that are used for breeding

by threatened species and because silvicultural practices will slowly reduce the number of cavity bearing trees in the forest.

(See comment 65)1.3.5 No research has been undertaken to determine the nesting requirements of other indigenous species in the Maruia working circle (particularly 6 indigenous cavity-nesting species). This information is needed to assess whether the harvest prescriptions would impact on these species. Specifically, these species may add to the cumulative number of cavity bearing trees per ha required for breeding wildlife in addition to the 14 trees/ha required by threatened species).

1.3.6 The above calculations do not provide any estimates for other cavity-using pest species in the Maruia forest ( e.g. rats, wasps, starlings) which may out-compete indigenous species seeking cavities for breeding. These species may add to the cumulative number of cavity bearing trees per ha required for breeding wildlife.

(See comment 66)1.3.7 The protection of all podocarps, rata, and beech >110 cm DBH is a good first step towards mitigating the effects of harvesting on threatened species.

1.3.8 In addition, no standing dead trees should be felled because they provide important wildlife habitat.

(See comment 67)1.3.9 Setting the maximum harvesting limit of beech at 80 cm DBH rather than 110 cm) would mean that the majority (ca. 80% of cavity breeding and roosting sites for threatened species would be retained. This would reduce the harvest by a maximum of 10% - but would probably have a lesser impact on wood volumes recovered because a high proportion of wood from trees >80 cm DBH will be "defective".

(See comment 68)1.3.10 The harvesting rates per ha prescribed in the plans may be higher than the 1.009 trees/ha/yr because additional trees will be felled for roads, landings, firewood and health and safety. it is unclear from the documents what the real harvesting rate will be, but they may be greater than the level prescribed.

(See comment 69) 1.3.11 "improvement felling" of immature "defective" stems (set at 2.36/ha/yr) will limit the potential pool of trees which will develop cavities (e.g. for nesting and roosting) in the future. It is not known what the long term impact will be, but if 19% of young, "deformed" red beech are felled per rotation, this would have a significant impact on the occurrence of cavity bearing trees in future generations.

(See comment 70)1.3.12 The MSMP acknowledges that research on recruitment of new trees in these beech systems is required. Without this research, no-one will be able to assess if the annual rate of felling (especially in the larger tree size classes) will in fact mimic natural processes and be sustainable.

(See comment 71)1.3.13 Surveys of the frequency of availability of cavity-bearing trees within the TWCL working circles would provide more precise prediction of the effects of harvesting on threatened species.

(See comment 72)1.3.14 Climbing trees before felling would provide the only accurate means of assessing presence of cavities.

(See comment 73)1.3.15 A study of the foraging preferences of birds within the area would improve predictions as to whether the management regimes proposed would leave sufficient foraging habitat for populations to remain viable.

(See comment 74)1.3.15 (sic) Unless long-tailed bat roosting areas in the managed forests are identified prior to harvesting, then patchwork felling (tree group selection) would increase the probability of devastating bat populations. Long-tailed bats roost in relatively small patches of forest, usually in clusters of trees.