Data from: How many broadleaved trees are enough in conifer plantations? The economy of land sharing, land sparing, and quantitative targets

1. For biodiversity conservation to be an effective and significant social investment, non-marketed values of biodiversity conservation and its associated opportunity costs should be evaluated in monetary terms. 2. In this study, we measured the willingness to pay (WTP) for bird abundance using a choice experiment (CE) based on the random utility model. We performed a cost–benefit analysis to identify the optimal proportion of broad-leaved trees in conifer plantations on a volume basis to maximize the social benefits of bird conservation and wood production. 3. The results suggested that respondents to the CE were not satisfied with their current situation and preferred an increase in bird abundance. However, the estimated WTP indicated diminishing returns of bird conservation. More specifically, WTP first greatly increased before gradually experiencing decreasing marginal values, reaching its peak, and finally decreasing slightly with increasing bird abundance. 4. Optimization analyses indicated that when the relation between bird abundance and broad-leaved tree proportion was convex, semi-natural plantations with non-zero broad-leaved tree proportion (0.02–0.22) were always optimal options. When the relation was linear, optimal broad-leaved tree proportion ranged from 0 to 0.78 and was greatly affected by wood values. When the relation was concave, there were only two optimal broad-leaved tree proportions: a very high proportion (approximately 0.90) and the lowest possible proportion (0). When the convex and concave relations approached the linear form, comparable benefits could be attained across broad ranges of broad-leaved tree proportion both within and across the relations. In such cases, it would be useful to increase the likelihood of a feasible land-use strategy of either land sparing or land sharing in order to be successful. 5. Synthesis and applications. It can be difficult to set quantitative targets in biodiversity conservation solely on an ecological basis, and social benefits of biodiversity conservation can create diminishing returns in many situations. The framework we proposed shows how to reconcile resource production and biodiversity conservation in the real world.

1. 若要使生物多样性保护成为兼具实效与重要价值的社会投资，则需以货币化方式评估生物多样性保护的非市场价值及其关联的机会成本。2. 本研究基于随机效用模型（Random Utility Model），采用选择实验（Choice Experiment, CE）法量化了民众对鸟类丰度提升的支付意愿（Willingness to Pay, WTP）；并开展成本效益分析，以体积占比为基准，确定针叶人工林中阔叶树的最优占比，从而最大化鸟类保护与木材生产的社会效益。3. 研究结果显示，选择实验的受访者对当前状况并不满意，且更倾向于提升鸟类丰度；但估算得到的支付意愿表明，鸟类保护存在收益递减现象。具体而言，随着鸟类丰度提升，支付意愿先大幅上升，随后边际价值逐渐递减并达到峰值，最终小幅下降。4. 优化分析结果表明：当鸟类丰度与阔叶树占比的关系为凸函数时，阔叶树占比非零的半天然人工林（0.02~0.22）始终为最优选择；当二者关系为线性时，阔叶树最优占比区间为0~0.78，且受木材价值影响显著；当二者关系为凹函数时，仅存在两类最优阔叶树占比：极高占比（约0.90）与最低可能占比（0）。当凸、凹函数关系趋近于线性时，在两类关系内部及跨关系的宽泛阔叶树占比区间内，均可获得相近的效益。在此情形下，为实现保护目标，提升采用土地保留（land sparing）或土地共享（land sharing）这类可行土地利用策略的可行性将颇具裨益。5. 综合与应用：仅基于生态学依据设定生物多样性保护的量化目标往往颇具难度，且在诸多情形下，生物多样性保护的社会效益会呈现收益递减特征。本研究提出的分析框架，阐明了在现实世界中如何协调资源生产与生物多样性保护的路径。