Science on the Pulse: Top reads from November

Dooley and colleagues made efforts to advance methods and understanding in this field with their recent publication in Ecology Letters testing of the effects of diversity in multi-functionality using a multivariate model which found support for the diversity/multi-functionality hypothesis - their framework and methods will certainly be of interest to those of working to test these ideas in agricultural systems and landscapes. 

Focusing on a singular ecological function, some of the notable highlights including work by Josiah and colleagues in PNAS on the impact of bats on reducing pests in maize fields. There has been lots of innovative work on bats in coffee and cacao systems, but what really caught our eye here are bats and maize - this is not where we might have first thought to look for bat provided agroecosystem services! 

Not only did Josiah’s bats suppress insect pests, but they also apparently suppressed several fungal pathogens and aflatoxins associated with those pests. With more than $1 billion in services provided by bats to maize fields annually, it may be time to see these eerie-creatures of the night as helpful neighbours and start to invest in habitat, or a least in bat boxes. We’ll take this opportunity to briefly flag an interesting piece by Offenberg reviewing “ants as tools in sustainable agriculture” in the journal of Applied Ecology. 

Ask not what biodiversity can do for you, but what you can do for biodiversity.

We do tend to focus on the functional side of biodiversity in agricultural systems, but it’s also good to recognize agriculture’s impacts on biodiversity. Perrings and Halkos in IOP conduct a much needed  study of the impact of agricultural expansion versus intensification on SubSaharan biodiversity. Their results show agricultural extensification is associated with increasing threats to biodiversity at all time scales, whereas intensification drove a significant reduction in threat across long time scales. 

Of course one of the founding ideas of biodiversity and ecosystem service research is that biodiversity conservation and ecosystem service provisioning are linked. Agricultural expansion driving forest fragmentation and loss has obvious impacts on habitat conversion, but  Bregman and colleagues also demonstrate that fragmentation impacts the species interactions that regulate the collapse of biodiversity and the services it provides, particularly seed dispersal and pest control within agricultural landscapes. ​

When we see papers about the influence of climate change on natural vegetation patterns, its forces us to ask how agriculture can positively respond to such changes. A hypothesis that is never far from the back of our minds is that efforts to make agriculture more sustainable become more expensive/challenging the further an agricultural system departs from its baseline natural system position. But what happens when this baseline shifts? 

A paper by Gherardia and Sala in ​PNAS caught our attention here in demonstrating that increasing precipitation variability, which is a condition many CGIAR farmers are faced with, drives a transition from grassland to shrubland vegetation. Changes in precipitation variability decreased grassland productivity by 81%, but increased shrubland productivity by 67%. 

This begs the question as to which crops may become the most suitable for rainfed systems under shifting climate regimes, particularly in sub-Saharan Africa. Meanwhile, Panagos and colleagues take a breather to consider the impact of Europe’s Common Agricultural Policy on soil conservation using RUSLE2015. Many of our team members are familiar with USLE/RUSLE as a core element of the NatCap InVEST toolkit for targeting ecosystem service based interventions. 

Panagos and friends show that over the past decade, the European guidelines for soil protection have reduced soil loss rate by 9.5% on average in Europe. Still a way to go, but good signs of progress - slow and steady wins the race. We’d love to see a similar study for Africa, maybe by having Pagnos team up with Kaptue’s work mentioned below.

Why do we need an eye in the sky?

So how do we apply what we know about biodiversity to help solve practical challenges in ecosystem service management? Well, a good starting point is finding ways to measure and monitor change in biodiversity-related variables. Many of our readers will be aware of the challenges of measuring the impact of biodiversity and ecosystem service change over large areas and long time scales, particularly the case in fast paced global environment where band-aid solutions seem to be drowning out the value of long term visions and approaches to sustainability. 

Biodiversity itself is a tricky subject, with plenty of debate (and misconceptions) as to what it is, and how to measure it. Petrou and colleagues provide a handy synthesis of the capacity of different satellite sensors to track biodiversity variables for monitoring progress towards the 2020 Aichi targets, showing that freely available data can now be used to track changes in 12 headline indicators.  Progress in using remote sensing technologies in ecosystem science continues to grow and we think these approaches will be increasingly important as countries seek methods to meet monitoring requirements for the SDGs. For example, Kaptue and colleagues in PNAS detect regional greening trends in sub-Saharan Africa despite regional differences in the extent and direction of change. Their work and methods sound quite promising both for assessing the impact of large scale interventions over time, but more importantly for targeting degradation hotspots where restoration is most needed. 

Finally, in case you missed it.

Because we’re embarrassed to say that we sure did - PNAS dedicated its 100th anniversary issue to Natural Capital. This is a great issue with twelve specific papers from the ecosystem service research community on ecosystems services and natural capital. 

See the core concept section by Amy West on “Ecosystem Services” which is open access and gives a nice one page synopsis of the state of the art. The articles including in the special issue span a broad range of tropics on ecosystem services - however the main thread that we found of interest the movement from “promise to practice” and growing evidence of ecosystem services and natural capital making their way into the private sector, and legislative planning. 

We’re pleased that PNAS chose a topic so near and dear to our hearts to celebrate its 100th year and wholeheartedly support to need for ecosystem service research to become practical.