Biodiversity: ecosystem function

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Video of short documentary Jena Experiment Intro Video shared by Guangjuan Luo.

  The world is currently losing animal and plant species at an unprecedented rate. Unfortunately Australia is the world leader in this field! 

Mainly due to the destruction of wildlife habitats around one-third of all species are threatened when we lose species we also lose important ecosystem functions that we as humans depend on this is currently being investigated in one of the biggest and oldest long-term projects in a grassland model ecosystem the yena experiment.  Jena experiment is very special we are not only investigating the communities of different organisms from bacteria to mammals in great detail but we are also investigating element cycling nitrogen phosphorus and water cycling and carbon.

 Our first results was the plant productivity increased with increasing plant species richness. That means that meadows with higher diversity produce more biomass. Now we want to understand the mechanisms that underlie this effect the researchers always compare plots containing low plant diversity with ones containing high plant diversity 

They not only want to know where the plants grow well together or whether they compete but also how plants microorganisms and animals influence each other they show that plant diversity had a positive effect on the diversity of other organisms. 

For example in species rich grasslands there are more species of pollinators. Pest increases are less pronounced and more earthworms are altering the soil structure allowing plant roots to have better access to rain and soil water this means that a diverse ecosystem can have a positive influence on functions that are also important for human well-being.  For instance yield increases and soil erosion control a second important aspect is the role of biodiversity in carbon and nutrient cycling. 

The researchers collect water samples from different solvents and analyze the dissolved carbon contents and nutrients in the laboratory soil samples are prepared to extract nutrients.  Their amount in combination gives information on soil fertility and how well plants can access the nutrients. 

The focus is on phosphorus compounds and different nitrogen compounds such as ammonium nitrate and amino acids results show that the soil from high diversity grasslands contains diverse dead plant and root material and the roots release a high variety of organic compounds. Microorganisms are benefiting from such a wide resource supply with increases being recorded in both their diversity and activity this means that they convert more dead plant biomass and root exudates into microbial products and contribute to long term carbon storage in the soil.

 For humans this has important implications relating to climate change mitigation. Furthermore a larger pool of nitrogen compounds is available especially in species rich grasslands. Plants search furnishes to receive nutrients from deeper soil layers. This additionally prevents nitrates from leaching into the groundwater. 

So diverse ecosystems are more productive but are they also more flexible

 The researchers got answers to this question after the summer of 2013 when the adjacent Sala River suddenly flooded the whole research area for 14 weeks. We need to measure what happens, we measured everything. 

One can imagine after the results were analyzed it became apparent that diverse grasslands recovered faster. Here there were more survivors among the many different species. Some even grew better and could compensate for the losses of others and therefore stabilize the system 

 Important implications for the question how important is biodiversity for ecosystem functioning.  We assumed that diversity had a week or a saturating relationship with ecosystem functioning. This would mean that a loss of species at high diversity would have hardly noticeable effects on ecosystem functioning when they are read through the language when we look at the long term data.  We see such strong effects that biodiversity effects different processes almost linearly and this means that over time we would notice the loss of every single species in an ecosystem.

The Jena experiment as a unique long-term project shows why diversity Co systems are more productive and more stable than simplified ecosystems.

 in the future in addition to plant diversity researchers also want to manipulate the diversity of other organisms of the food web and they aim to compare their results with other experiments across the world to understand bit-by-bit ecosystems and their merit as a whole before they are fundamentally changed.

Feb 13, 2017 Thanks for sharing
Guangjuan Luo & all the team on the Jena Experiment