The State of the World's Plants report 2017

Climate Change 

Professor Willis led the team which authored the chapter on climate change that looks at the winners and losers in the plant world under a changing climate. They reveal that plants with thicker leaves and bark, more efficient water use strategies, deeper roots and higher wood density are better able to cope with future climate change. These include increases in drought, fires, temperature and CO2. Deeper roots are found to be better able to withstand drought as are trees with high wood density.  Thicker leaves and taller grasses appear to do better in higher temperatures but conversely shorter trees do better overall. Plants that possess a combination of these traits will be the winners according to these findings.  

“It’s a different way of thinking, to look across biomes and examine which traits plants already possess that allow some to better tolerate the cocktail of climate change that will impact our ecosystems. The interesting fact to emerge is that the suite of ‘beneficial’ traits are, on the whole, the same the world over and are as true in a temperate forest as in a desert.” 

This can help to inform land use decisions like encouraging farmers to leave long rooted grasses on drought prone lands instead of removing them in favour of short rooted crops like wheat. When this happened in the US in the 1930’s the famous Dust Bowl storms ensued with disastrous ecological consequences.

Plant Health 

The report also looks at the big issues facing plant health globally with a focus on the methods being used to control the spread of pests and pathogens. It calculates that $540bn/yr is the potential cost to world agriculture if the spread of invasive pests and pathogens is not stopped. The main reason for the scale of the problem is the increase in trade and travel due to globalisation which has contributed to the spread of pests and pathogens around the world. Trade in live plants is especially dangerous and the report recognises the need for stricter biosecurity measures.  The report lists the top 20 pests known and the efforts to control them.   Maize in Africa is being decimated by the Armyworm leading to starvation as well as rising food prices worldwide. The American ash species pathogen, emerald ash borer EAB, could cost the US over $300bn according to the research.

• The number of plants with assembled whole genomes now stands at 225 and has risen by over 60% the last year alone. The report highlights information on how new technology is helping to speed up the discovery and classification of plants that are providing important sign posts to the next food crops, the effectiveness of conservation policies and actions in protecting some of the most important plant species globally.  For example, the sequence for one of the most widely used herbal medicines Chinese liquorice was revealed in 2017.
• In the world of crops, rice registered the largest increase in the numbers sequenced but there remains much to be done.  When added to the information being gathered on the wild relatives of crops like rice, wheat, peanuts, potatoes, tomatoes, soybean, sweet potato and others, we have a growing picture of what we need to do to sustain our growing global population in a warming world. Even hops and grapes used in beer and wine have been studied this way to shed light on taste and quality as well as to increase yields in the longer term.

• The country focus of this year’s report is Madagascar, the 4th largest island on earth and the only country where Kew has a permanent presence outside of the UK.  The report looked at the data available on the island using new analytical tools and perspectives. It concludes that 83% of Madagascar’s 11,138 native species of vascular plant occur nowhere else on earth and the size of its flora is equal to that of Uganda, Kenya & Tanzania combined.  The world's 4th largest island is home to five unique plant families and three times as many palm species as continental Africa. Madagascar has some spectacular unique palms - Tahina spectabilis, the giant suicide palm (known from) / found in just 2 localities. But the majority of Malagasy palms are the result of massive speciation in a single genus Dypsis into many habitats – hence why 83% of Madagascan species are endemic. 

Dr. Tianjanahary Randriamboavonjy, KMCC Communities Team Leader at the RBG Kew office in Madagascar (who will be attending the press launch and speaking at the report’s Symposium on May 25-26th) says: 

“Madagascar is known for its high level of endemism of plants and animals, but the diversity within Madagascar creates a huge challenge for conservation. Every fragment of remaining forest might contain new and undescribed species so we should re-evaluate our strategy to protect everything that is left. A report like this allows us to do this on the best scientific evidence available and with the participation of local people so we hope it will be heeded and lead to action.”

• Plant conservation policy is also put under the microscope in this year’s report.  As a result of CoP17 an additional 304 species have been added to over 31,517 plant species currently listed on the CITES Appendices - lists of species afforded different levels or types of protection from over-exploitation. It reveals that there are many individual orchid species that are as threatened as the White Rhino, like Asian slipper orchids and many of Madagascar’s orchids.  Also trade in rare species shows no signs of abating. CITES legal plant trade into the EU in 2014 was worth US$286million with 2,320 plant taxa imported. The Illegal trade within the EU in wild species was estimated to be worth between €8-20 billion annually (EU 2016). The report demonstrates some of the ’Biodiversity Blunders’ that people commit when travelling around the world in a graphic image listing some of the cacti, herbal medicines, wood and food supplements that are illegal to move without certification.
• 6,075 vascular plant species are now documented as invasive.  The report reveals that 44% of studies on the control of invasive plants in natural ecosystems examine the use of chemical methods.  The choice of control method currently appears to depend on the plant form i.e. whether it’s herbaceous or woody, but the report suggests that not enough is being done to understand what is actually most effective for a particular plant in a particular place and time. The report suggests that in many cases we are ‘fighting a complex  battle’, using the example of tree controls from South Africa and the trade-offs between a tree that is an invasive on one hand, and an important provider of fuel and food to local communities on the other.
• New research reveals that there is only 53% congruence between Important Plant Areas (IPAs) and Important Bird and Biodiversity Areas (IBAs) across Europe and Mediterranean region.  This tells us that if we want to effectively prioritise conservation efforts, then a range of organism groups (e.g. birds, plants, butterflies etc.) need to be studied, as different sites are often of importance for different groups (i.e. we can't rely on animal-focussed conservation to protect our plant diversity). The chapter also reveals the most important sites for plants in Europe’s Mediterranean region are currently facing threats but, as many of these are at least partially protected by law, there is an opportunity to better manage these sites for their plants.
• Extinction risk is examined in more depth this year from the perspective of which plant traits help predict their fate,  concluding the epiphytes and late bloomers may be more vulnerable to extinction than other plants.  It argues that reliable predictors of extinction risk are needed to improve conservation planning.  This is the first review on this scale that examines the evidence for those traits that might influence extinction risk in plants.

ENDS