Summary & Recommendations
54. This is accepted by TWC in its plans. The dispute is whether or not the proposed protocols are likely to increase risk for these species.
55. There is no dispute that food and nest/roost sites are also needed alongside predation control to safeguard the endangered species. The dispute is on whether the proposed logging will reduce hole or food availability in any way that increases the risks to the birds and bats.
56. The DoC Critique has continually emphasised these warnings without adequately or repeatedly acknowledging that the new style of logging is so different from past practices that impacts are likely to be very much reduced (potentially even eliminated).
57. These are now proposed.
58. Mitigation procedures proposed by TWC by continual predator control and funding of research on forest processes and biodiversity management have not been acknowledged in the DoC Critique. A legitimate criticism (Colin O'Donnell, in litt. 5 October 1998) in my view is that these plans ( which I know about and have seen go in to the Okarito and Saltwater Plans) are not well specified in the management plans now going to public viewing. DoC and public assurance would grow if the planning was more explicit about just how much control effort will happen and where. In these ways the proceeds of sustainable timber production can be diverted back to create net conservation benefit for TWC forests and greatly assist DoC's national effort. Some bird (and bat?) recruits may flow onto nearby DoC estate where shortage on funds precludes their own "mainland island" restoration project.
58a. It is impossible to independently assess the validity of this statement (i.e. the "the only significant populations known ... outside eastern Fiordland") until data from the national bat survey efforts promulgated in recent years have been completed.
59. No effects have been proven nor demonstrated to even be likely. A need for further research is indicated before the validity of the DoC Critique's conclusions can be formally assessed.
60. At the outset the DoC Critique is quite explicit that the approach taken here is indicative of the approach they recommend, and not a reliable indication or exact prediction. This caveat was lost sight of as the Critique progresses and is not evident in this summary statement. My rejoinders to the DoC Critique has outlined numerous unstated assumptions and several omissions, all of which increase perceived risks to bats and birds. Most critical of all is an unchallenged and as yet scientifically indefensible assumption that nest holes limit current population abundance, and that grouped tree removals will reduce cavity abundance in ways that will reduce population density. The second most important omission has been a lack of acknowledgement of tree growth and recruitment (projections in the DOC Critique are for static scenarios), and for no forest compensatory changes in growth and demography. In a myriad of smaller ways the risk assessment has only stressed one side of processes or unstated assumptions of additive effects. The critical need is for a model to predict the number of holes remaining after several rotation cycles, and research to predict whether the new levels of hole availability would significantly cap resurgence of numbers of hole users following predator control .
61. But no evidence for New Zealand, and sound ecological reasons for predicting that predation has lowered density to well below the carrying capacity where tree cavity limitation affects populations. Evidence from broadly similar habitats in the Eglinton Valley by the DoC team shows evidence that holes are not limiting, and repeated lines of evidence that predation is depressing population abundance. Anecdotal evidence from around Nelson in honeydew forests also demonstrates that holes do not limit kaka numbers.
62. The basis for this calculation is flawed. Formal modelling of hole formation and depletion by grouped tree extraction, and of species hole requirements are needed to make it rigorous.
63. The basis for this calculation is flawed. Formal modelling of hole formation and depletion by grouped tree extraction, and of species hole requirements are needed to make it rigorous.
64. This calculation ignores the potential for compensatory changes in growth rate and survival caused by live tree removals. It is not known whether the cavity formation in large trees is a size of age per se, (sic) or size per se, or some combination of the two. Measures of rate of tree cavity formation in the managed forest system are needed to evaluate this potential compensatory effect.
65. No evidence of nest site limitation is available for any New Zealand bird, or for bats. Several of the species mentioned in this regard by the DoC Critique are not obligate cavity nesters, so their numbers may be little effected (sic) even if hole availability was a regulatory factor.
66. The DoC Critique only presented projections for removals above 80 cm DBH. The calculations presented were flawed in that they took no account of hole formation as trees grow into the larger sizes (sic) classes. Modeling is needed of scenarios where all 100 cm DBH trees are left in situ (all proposed protocols by TWC's plans), and measured rates of cavity formation are all included to see if they are a sufficient safeguard for biodiversity values in their forests. Only modelling, professional monitoring and an adaptive management approach will be able to rigorously answer the crucial ecological questions involved .
67. Modelling should allow calculations of these economic and ecological risk scenarios. Different maximum DBH extraction regimes could be one variable altered in an adaptive management framework .
68. These are likely to be very minimal effects. A rigorous calculation by TWC could remove all doubt.
69. Modelling can predict whether such effects are likely to significantly alter cavity availability. This is the most significant of all the DoC Critique concerns (Colin O'Donnell, in litt. 5 October 1998. If an appreciable decline in the number of suitable holes is predicted, potential curtailment of the long-term recovery of bats and birds (following successful predator control) is possible. Holes are formed following environmental damage during its life cycle (usually branch breakage following heavy snow or wind, but sometimes from bruising as a nearby tree falls). Fungi then gain entry and rot enlarges the cavity. This process is most unlikely to be influenced by the shape of the tree in the forester's sense, which is the criteria (sic) used for "improvement felling" (Ian James, pers. comm. 7 October 1998). I think that it is most unlikely to suppress population abundance below that existing now, or that persisting if the forests in question were to be preserved as part of the DoC estate. Nevertheless if the proposed mathematical simulation of hole availability causes concern, TWC might need to consider reviewing its "improvement felling" strategy in order to safe-guard its biodiversity goals.
70. This research is planned by TWC.
71. Such research is now planned .
72. Some climbing may be done, but other measures may be taken from felled trees. Colin O'Donnell ( in litt, 5 October 1998) warns that cavities can shatter, or be filled in, or deformed when a tree is felled. Entrance dimensions can still be measured sometimes.
72. Studies of foraging preferences are a valuable first step but can not determine whether food limits the population in any way; let alone predict logging impacts .
74. This alarmist statement is very speculative.