Land-use trajectories for sustainable land system transformations: Identifying leverage points in a global biodiversity hotspot

Abstract

Sustainable land-system transformations are necessary to avert biodiversity and climate collapse. However, it remains unclear where entry points for transformations exist in complex land systems. Here, we conceptualize land systems along land-use trajectories, which allows us to identify and evaluate leverage points, i.e., entry points on the trajectory where targeted interventions have particular leverage to influence land-use decisions. We apply this framework in the biodiversity hotspot Madagascar. In the northeast, smallholder agriculture results in a land-use trajectory originating in old-growth forests and spanning from forest fragments to shifting hill rice cultivation and vanilla agroforests. Integrating interdisciplinary empirical data on seven taxa, five ecosystem services, and three measures of agricultural productivity, we assess trade-offs and cobenefits of land-use decisions at three leverage points along the trajectory. These trade-offs and cobenefits differ between leverage points: Two leverage points are situated at the conversion of old-growth forests and forest fragments to shifting cultivation and agroforestry, resulting in considerable trade-offs, especially between endemic biodiversity and agricultural productivity. Here, interventions enabling smallholders to conserve forests are necessary. This is urgent since ongoing forest loss threatens to eliminate these leverage points due to path dependency. The third leverage point allows for the restoration of land under shifting cultivation through vanilla agroforests and offers cobenefits between restoration goals and agricultural productivity. The co-occurring leverage points highlight that conservation and restoration are simultaneously necessary to avert collapse of multifunctional mosaic landscapes. Methodologically, the framework highlights the importance of considering path dependency along trajectories to achieve sustainable land-system transformations.

Keywords: Madagascar; agroforestry; conservation; path dependency; restoration.

Fig. 1.

Methodological framework to identify leverage points along land-use trajectories. The framework starts with 1) the identification of relevant land uses within a mosaic landscape, followed by 2) multidisciplinary research (interviews, surveys, and literature) on the land-use history. With this knowledge, 3) a land-use trajectory is built, aligning conversions across multiple stages, following the trajectory downstream. Now, 4) multiple leverage points can be identified, depending on the complexity of the trajectory. Next, 5) data on biodiversity, ecosystem services, and agricultural productivity of each land-use type is collected. Then, 6) trade-offs and cobenefits of conversion options can be evaluated against the current land use at leverage points (here, leverage point 2). This knowledge can inform interventions, showcasing which cobenefits can be harnessed and which trade-offs need to be mitigated under various conservation and conversion options at each leverage point.

Fig. 2.

Hypothesized outcomes for ecosystem services and biodiversity along the predominant land-use trajectory in northeastern Madagascar, with leverage points 1 to 3. We define leverage points as distinct points along a land-use trajectory, where land users face alternative land-use options with potentially contrary outcomes. At each leverage point, the current land use could be conserved or converted into one of multiple alternatives, suggesting strong leverage for interventions targeted to these points. Importantly, we can then evaluate the conversion options against the conservation option and against each other in terms of ecosystem services, biodiversity, and agricultural productivity. The relative position on the y axis for each land-use type represents hypothesized outcomes for ecosystem services and biodiversity.

Fig. 3.

Comparison of biodiversity, endemic biodiversity, and ecosystem services at leverage points 1 to 3 along the predominant land-use trajectory of northeastern Madagascar. Leverage point 1: conserving old-growth forest is necessary to retain many endemic taxa and ecosystem services. Conversion to shifting hill rice cultivation has overall stronger negative effects than conversion to forest fragments. Leverage point 2: conserving forest fragments is important to retain biodiversity and ecosystem services, but the lack of agricultural productivity encourages their conversion. After conversion, forest-derived agroforests outperform shifting hill rice cultivation across variables. Leverage point 3: cobenefits are possible under conversion of fallow land to fallow-derived vanilla agroforestry, given stable multidiversity and ES-multifunctionality and a strong increase in profitability. Dots and lines (mean and 95% CI) represent proportional deviation in biodiversity or ecosystem services resulting from land-use conversion. If the 95% CI does not include zero, this indicates significant differences between land-uses. Values of −1 indicate a 100% decrease (complete loss), and values of 1 indicate a 100% increase in biodiversity or ecosystem services when compared with old-growth forest, forest fragments, or woody fallow.

Fig. 4.

Variation along the land-use trajectory for multidiversity (A), endemic multidiversity (B), and ES-multifunctionality (C) and their trade-off with agricultural productivity (D) in northeastern Madagascar. Losses of multidiversity (A), and to a greater extent endemic multidiversity (B), happen after old-growth forest conversion. Changes at later transitions within the land-use trajectory (leverage points 2 and 3) are less strong. ES-multifunctionality (C) follows the same pattern. Trade-offs with agricultural productivity (D) become apparent as the most biodiverse and multifunctional land uses (old-growth forests and forest fragments) have no farming outcomes, while the most high-yielding land use (rice paddy) has the lowest value for biodiversity and services. Vanilla agroforests offer a compromise. Multidiversity (A and B) and ES-multifunctionality (C) are calculated as the proportion of taxa or services that reach 50% of the species richness or value of the five best-performing plots (50% threshold). Points colored according to the land-use type represent the mean value for each land-use type, while error bars are 95% CIs. The parallel coordinate plots (D) each depict one focal land-use type (color) in relation to the other six land-use types (gray). To enable comparison across variables, values are standardized so that zero represents the mean across all seven land-use types. Values at the 20% and 80% thresholds are displayed in SI Appendix, Fig. S2. Multidiversity and ES-multifunctionality are positively correlated (SI Appendix, Fig. S3).