Using biosphere metrics to assess the Planetary boundary for functional biosphere integrity

In the recent update of the Planetary Boundaries framework, Richardson et al. propose to use human appropriation of net primary productivity (HANPP) as a new indicator for the functional biosphere integrity boundary. They provide a planetary scale analysis and suggest to further complement this by an ecological metric.

To aid with the spatially explicit analysis of both HANPP and an ecological metric in an automated and easy way, we developed the "biospheremetrics" R package. The package combines 2 complementary metrics:

The BioCol metric operationalizes the HANPP framework in order to represent a meaningful Planetary Boundary indicator, and is accompanied by the EcoRisk metric, which quantifies biogeochemical and vegetation structural changes as a proxy for the risk of ecosystem destabilization. Both metrics are computable in a dynamic global vegetation modelling framework.

We spatially explicitly analyse both metrics over the past 500 years with simulations of the dynamic global vegetation model LPJmL and find that presently (period 2007-2016), large regions show modification and extraction of >25% of the preindustrial potential net primary production, leading to drastic alterations in key ecosystem properties and suggesting a high risk for ecosystem destabilization. In consequence of these dynamics, EcoRisk shows particularly high values in regions with intense land use and deforestation, but also in regions prone to impacts of climate change such as the arctic and boreal zone.

We additionally show how both metrics could be combined to inform the Planetary Boundary of functional biosphere integrity, compare our results with other spatially explicit global biosphere integrity metrics and discuss the setting of (provisional) thresholds.