The Planetary Boundary Framework: How Biodiversity Supports Us

We, as human beings, rely on our planet. The earth, and the creatures that we share it with, provide the food, water and air we need to live. But the planets’ ability to support us is being challenged by a problem of our own making; climate change. 

Awareness and anxiety around this issue has skyrocketed in the last few years, and for good reason. But before we can try and attempt to reverse climate changes’ effects, we need to know what they are; what are the essential parts of the planet that are under threat, and how will it affect us if we let it go too far? How far is too far? It is vital to quantify and measure such needs to forewarn disasters and target interventions to reduce climate change effects. In 2009 a group of scientists led by Johan Rockstrom conceived the planetary boundary framework, defining a collection of boundaries within which humanity can continue to develop and thrive for generations to come. Humanity needs to remain within nine boundaries to be in a safe operating space: climate change, chemical pollution, stratospheric ozone depletion, atmospheric aerosol loading, ocean acidification, nitrogen, phosphorus, freshwater use, land system change, functional diversity, and genetic diversity. Five of these boundaries have already been breached and two of these boundaries are still undefined; genetic diversity, and the subject of this post, functional diversity. 

Functional diversity is a measure of the range of things that organisms do in communities and ecosystems. For example, within a forest, squirrels might spread seeds, bees might pollinate flowers, and fungi might break down wood. However, different ecosystems will have different natural/optimal levels of functions, depending on the conditions and resources that are available. So how do we set a planetary boundary for the world’s functional diversity?

Biodiversity is both threatened by climate change and key in defining these boundaries. Although the connection between biodiversity and climate change is highly acknowledged, the dynamics between these are poorly understood. A study by Pakeman et al. (2017) of functional diversity changes in 561 

Scottish grasslands resurveyed 40 years on from initial grassland surveys, offering insight into the slow and subtle changes in habitat that have occurred over time. The changes detected correlated with changes in environment, such as weather patterns and land use changes. However, the changes in functional diversity were worse in highly productive, intensively farmed sites, demonstrating that land management also plays a large part. Alarmingly an overall shift in flowering species was detected, transitioning towards later-flowering species. This has repercussions on pollinator populations by reducing early season resources for pollinators. This resource decline was seen across all sites. Furthermore, the utilisation of Scottish grasslands has split in two; more productive lowland grasslands are now used more intensively than before, with only a few species of plants remaining, creating the familiar grass monoculture. The less productive grasslands, such as those on higher ground, appear to be less exploited over time and have managed to retain more species, and therefore can deliver greater ecosystem functionality.

 

The loss of functional diversity is of concern particularly in the Northeast of Scotland, where some of the highest rates of plant diversity loss can be found. Plants are both among the greatest providers of functional diversity and one of the most poorly understood, and more research is needed before we can decide on a safe planetary boundary which will allow the planet to continue to provide for us. 

 

We at The Habitat People are using our wildflower nursery of locally collected seed to bolster and create local populations of grassland species. We hope this will provide long term preservation of functional diversity on our sites, and may cultivate a living reserve of plants for years to come. 

 

Pakeman, R.J., Hewison, R.L., Riach, D., Fisher, J.M., Hurskainen, S., Fielding, D.A. and Mitchell, R.J., 2017. Long-term functional structure and functional diversity changes in Scottish grasslands. Agriculture, Ecosystems & Environment, 247, pp.352-362.

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