394 F. J. F. Maseyk et al.


TABLE 1 Categories of actions to achieve biodiversity gains within offset exchanges. Although protection, maintenance and enhancement actions can occur independently, they are often implemented together. Maintenance and enhancement actions can be similar, and both can occur at offset sites that have been protected.


Type of actions Description Protection


Designed to generate offset gains by avoiding or reducing the likelihood of the loss of extent (area) of biodiversity at a site; typically achieved by changing the legal status of the land, or sea, to restrict use rights


Maintenance Designed to prevent declines in biodiversity condition&thus maintain biodiversity in the condition it was at the start of the offset activity; include actions targeted at specific processes affecting the condition of a site, or compromising species’ viability (e.g. exclusion of livestock causing habitat degradation, or control of invasive plant species)


Enhancement Aim to restore biodiversity values where declines have already occurred; designed to increase the condition of targeted biodiversity above its condition at the start of the offset activity; similar to maintenance actions, but generally need to be applied at greater intensity to reverse declines; may also include creation of biodiversity values in places where these have been lost, such as through translocations of threatened species, or habitat creation


FIG. 1 A conceptual illustration comparing estimated biodiversity gain from offset actions with the actual biodiversity gain achieved from these actions, showing the influence of miscalculating gains from preventing loss of area (protection actions) on the adequacy of a total offset package. In this example, the offset package uses a combination of protection and other actions (e.g. maintenance or enhancement actions) in the offset design; with protection actions to prevent the loss of area being used as the primary action to achieve the offset, and other offset actions being used to supplement protection actions to reach the total biodiversity gain required to offset losses. In Scenario A (no net loss) the biodiversity gain is correctly estimated; the total offset package is adequate to balance losses. In Scenario B (net gain), the anticipated gain resulting from protection actions was underestimated and total gain delivered is more than expected; the total offset package is more than adequate to offset losses. In Scenario C (net loss), the anticipated gain from protection actions was overestimated meaning the other actions proposed to make up the balance of the total gain requirement were inadequate; total offset package is inadequate to balance losses.


offset package risks under-delivering biodiversity gains (Fig. 1).


Biodiversity gain can only be generated by averting loss if there is a genuine threat (not related to the original


development project) that can be averted at the proposed offset site (Gordon et al., 2011; Maron et al., 2013). Iden- tifying these threats and estimating the likelihood of them leading to the site being lost (likelihood of loss in the future) is essential for estimating the expected amount of averted loss secured by an offset proposal (Maron et al., 2013). However, this can be challenging because many offset policies lack explicit assumptions about counterfactual scen- arios (i.e. the future situation in the absence of the offset ac- tion), empirical data to support estimation of the likelihood of loss, and guidance on how to use such data to construct plausible and robust scenarios of loss in the absence of the offset protection (Bull et al., 2015). Furthermore, lack of data to estimate likelihood of losses means having to rely on expert judgement in many cases, which is influenced by a range of cognitive biases. Where the likelihood of loss is overestimated this artificially inflates the perceived gain from protection, resulting in the offset exchange delivering insufficient actual gains to balance the losses (Maron et al., 2015).


Here, we present a method and decision tree to guide


consistent and credible estimation of the amount of bene- fit generated by averting the loss of biodiversity at a pro- posed offset site. Firstly, we review high profile examples of existing approaches used in offset policies and projects internationally to estimate the amount of offset benefit generated by improving formal or legal protection of bio- diversity. Secondly, we describe the calculation of the avert- ed loss component of a biodiversity offset, and provide clear guidance for determining which additional drivers of biodiversity loss, in which situations, are appropriate to incorporate into estimates of future biodiversity loss. To reduce the influence of cognitive biases, we propose that estimates of likelihood of loss should be derived primarily from recent average background rates of loss, typically re- cent rates of loss at similar sites (i.e. sites in the same region, with comparable habitat or species assemblages, and subject to similar anthropogenic influences). To illustrate our meth- od and decision tree, we focus specifically on averted loss of


Oryx, 2021, 55(3), 393–403 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000528


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164