Agriculture: Less productive yet more stable pastures

Climate change will have a considerable influence on the biodiversity and productivity of meadows and pastures. However, according to the results of the large-scale climate and land use experiment, GCEF, which has been conducted at the Helmholtz Centre for Environmental Research (UFZ) for 10 years, the extent of these changes depends on the land use. Grassland optimised for high yield responds much more sensitively to periods of drought than less intensively used meadows and pastures. According to an article recently published in Global Change Biology, this can certainly have economic consequences for the farmers affected.

Grassland is one of the most important and most widespread ecosystems on earth. Such open landscapes with grasses and herbs not only cover more than one quarter of the entire land surface but also store at least one third of the terrestrial carbon, are crucial for food production, and can be extremely species-rich in a relatively small area. But what is the future of these habitats? The study provides new insights into this question.

It has long been clear that two environmental changes are threatening the world's grasslands. Particularly in Europe, grasslands are now fertilised much more heavily, mowed more frequently, and grazed more intensively. In addition, farmers often sow only a handful of grass varieties that promise a particularly high yield. This intensification of land use is fundamentally changing the species composition and functionality of meadows and pastures. The same applies to climate change. For Germany, climate change will result in a shift in the seasonal distribution of precipitation as well as an increase in hydrological extremes (e.g. heavy rainfall and droughts), among other things. It is considered the second largest threat for these ecosystems.

When both changes come together, they can reinforce each other. However, nobody yet knows exactly what will happen. Most experiments on this topic have so far focussed on either the climate or land use. "What makes our study unique is that we investigated the interaction of both factors," explains Dr Lotte Korell, biologist at the UFZ and first author of the publication.

This was made possible by the large-scale and long-term experiment of the UFZ in Bad Lauchstädt near Halle, the Global Change Experimental Facility (GCEF). It consists of 50 plots, each measuring 16 × 24 m; these are used with varying degrees of land use intensity. Temperatures and precipitation levels can also be manipulated with the help of mobile roof systems. For example, some plots receive 10% more precipitation in spring and autumn and 20% less in summer than the untreated control plots. This roughly corresponds to the conditions that climate models project for central Germany.

An eight-year data series from this experiment has now been compiled for the new study. The researchers analysed the biodiversity and productivity of the plants on the differently used plots between 2015 and 2022. "This period includes three of the driest years this region has experienced since beginning of records," recalls Korell. These droughts apparently had a much stronger effect on the plants than the experimentally simulated climate change.

However, in both cases, the trend pointed in the same direction: species-rich grassland that is only rarely mown or sparsely grazed withstood the heat and drought much better than the intensively used high-performance meadows. "Among other factors, this is probably related to the diversity of species," says Korell. This varied greatly depending on the land use of the grasslands.

A diverse mixture of more than 50 native grasses and herbs grew on the less intensively used meadows and pastures of the GCEF. However, on the intensively used grassland, the UFZ team had sown only the five grass varieties recommended to farmers by the Saxony-Anhalt State Institute for Agriculture and Horticulture for drier sites at the start of the experiment. These included varieties of meadow grass (Dactylis glomerata) and perennial ryegrass (Lolium perenne).

Because such grasses are bred for maximum yield and were also heavily fertilised -- as is common in agricultural practice -- the intensive meadows were initially much more productive than the more diverse grasslands. However, they were able to make use of this advantage only in favourable climatic conditions and were not able to withstand the drought as well as the plants in the low-intensity meadows and pastures. In times of drought, the grasses in the intensively used meadows increasingly died back and were replaced by other species such as chickweed (Stellaria media), shepherd's purse (Capsella bursa-pastoris), dandelion (Taraxacum officinale), and small-flowered cranesbill (Geranium pusillum). "These are mostly short-lived species that survive as seeds," explains Dr Harald Auge, also a biologist at the UFZ and senior author of the study. When the more competitive plants succumb to drought, these species take the opportunity to invade their habitats: they either migrate from the low-intensity grassland or germinate from the seed stock in the soil.

This shift in species composition is not particularly welcomed by farmers, especially because most of the new arrivals have a lower fodder quality than the grasses originally sown. The common ragwort (Senecio vulgaris), which was frequently represented among the immigrating species in the experiment, is in fact poisonous. All of this reduces the productivity of the land.

Farmers have long been aware of this kind of degradation of high-performance grassland by immigrating species. They therefore expect to have to plough up and reseed their land every few years. "However, climate change may accelerate this need and lead to additional costs," says Korell. Perhaps everything will go well for a few years and it will rain enough. However, it is also possible that several dry summers will follow one another. Climate change is making conditions even more unpredictable.

Read more at Science Daily

Global study of extreme drought impacts on grasslands and shrublands

A global study organized and led by Colorado State University scientists shows that the effects of extreme drought -- which is expected to increase in frequency with climate change -- has been greatly underestimated for grasslands and shrublands.

The findings -- published in Proceedings of the National Academy of Sciences -- quantify the impact of extreme short-term drought on grassland and shrubland ecosystems across six continents with a level of detail that was not previously possible.

It is the first time an experiment this extensive has been undertaken to generate a baseline understanding of the potential losses of plant productivity in these vital ecosystems.

Melinda Smith, a professor in the Department of Biology at CSU, led the study and is the first author on the paper.

She said the observed reduction in a key carbon cycle process after a single 1-in-100-year drought event greatly exceeds previously reported losses for grasslands and shrublands.

"We were able to determine that the loss of aboveground plant growth -- a key measure of ecosystem function -- was 60% greater when short-term drought was extreme compared to the less severe droughts that have been more commonly experienced historically," she said.

"Past studies suffered from methodological differences when estimating the impacts of extreme drought in natural ecosystems, but our standardized, distributed approach here addressed that problem."

Smith added that the project also showcases the variability in drought response across grassland and shrubland ecosystems -- offering both a review of the global impacts of climate change as well as a glimpse into which areas will be most stressed or most resilient in the coming years.

Gathering global extreme drought data on grassland and shrubland ecosystems Known as the International Drought Experiment, the newly published research originally dates back to 2013 as part of the National Science Foundation's Drought-Net Research Coordination Network.

Altogether, there are more than 170 authors representing institutions from around the world cited in the new PNAS study, which was completed over the last four years.

To gather their data, researchers built rainfall manipulation structures to experimentally reduce the amount of naturally occurring precipitation available to ecosystems for at least a full growing season.

About half of the participating sites imposed extreme drought conditions with these structures, while the rest imposed less severe drought for comparison.

As Earth's climate continues to change, short-term droughts that are statistically extreme in intensity will become more common, with what were once considered 1-in-100-year droughts now potentially happening every two to five years, said Smith.

But because of the historic rarity of extreme droughts researchers had been unable to estimate the actual magnitude of their ecological consequences.

Smith said grasslands and shrublands were perfect test areas to fill that research gap because they are easier to manipulate for study than other systems, such as forests.

They also store more than 30% of the global stock of carbon and support key industries such as livestock production.

"They are key ecosystems that are scalable to the globe, which makes them highly relevant for this kind of work," said Smith, who also serves as chair of the Faculty Council on campus.

"Grasslands and shrublands cover between 30% and 40% of the globe and frequently see deficits in precipitation. That means they are more vulnerable to climate change."

Findings from the sites also provide insight into how specific climates, soil and vegetation types broadly influence drought response.

While the work shows that drier and less diverse sites like those in Colorado are likely to be the most vulnerable to extremes, Smith said the severity of the drought was the most consistent and important factor in determining an ecosystem's response.

"Our data suggests greater losses in drier sites, but if you are getting to the extremes -- which is what is being forecasted -- we can generally expect substantial losses no matter where you are in the world," she said.

"We also found that even moderate losses from less severe droughts would still likely result in large impacts to the populations that rely on these systems. And then there is a combined loss of function across the globe to consider as well."

Read more at Science Daily

Butterflies on the decline

Research shows that the numbers of butterflies in meadows and pastures of Europe are in a continuous decline. A new EU regulation aims to stop this trend.

Grassland butterflies will soon play an even greater role in EU nature conservation legislation. Based on the occurrences and population trends of butterflies, the member states are supposed to document the progress they have made in implementing the planned "Nature Restoration Law." The Butterfly Grassland Indicator, recently calculated for the eighth time by European foundation "Butterfly Conservation Europe," is to be used for this. This analysis, which also includes data and expertise from many volunteers in Germany -- coordinated by experts from the Helmholtz Centre for Environmental Research (UFZ) in Halle -- shows an urgent need for action. This is because the situation of grassland butterflies in Europe has deteriorated considerably since the first calculations in 1990.

The diagnosis sounds worrying: More than 80% of habitats in the EU are currently considered vulnerable. This has negative consequences on their functional capability and thus the services they provide for humans. In order to counter this, the European Commission has proposed a new set of rules. This "Nature Restoration Law" is one of the key elements of the EU Biodiversity Strategy 2030 to be published this May. It defines binding targets for the entire EU for the renaturation of various ecosystems. Two years after the regulation enters into force, member states must submit plans on how they intend to meet these targets. They must also document the success of their measures.

However, the latter is not so easy. So far, there are only a few indicators that can reliably show the state of biodiversity. For most animal and plant groups, there is a lack of comparable data across Europe from which to assess the development of populations. The few exceptions include birds, bats, and butterflies.

"Butterflies in particular are ideal bioindicators," says agricultural ecologist Prof. Dr Josef Settele from the UFZ. This is because these insects occur in a wide range of habitats and react sensitively to environmental changes. With their specific requirements, they are often representative of many other insects. Finally, they are eye-catching, attractive, and popular. It is thus relatively easy to motivate volunteers to take part in scientifically oriented butterfly counts.

Such actions are becoming increasingly popular. For example, in 2005 the UFZ and the Gesellschaft für Schmetterlingsschutz (GfS) launched a citizen science project called "Tagfaltermonitoring Deutschland" (Butterfly Monitoring Germany) in which anyone interested can participate. Since then, butterfly enthusiasts from all over Germany have been walking fixed routes from spring to autumn to record the number of individuals and species they have seen. Similar monitoring programmes now exist in most other European countries. "Around 5,000 volunteers spread all over Europe are now taking part -- all following the same protocol," says Settele.

The data are collected and analysed in the central "European Butterfly Monitoring Scheme" (eBMS) database, managed by UKCEH and mirrored at UFZ and the Dutch "Vlinderstichting." In this way, the population development of individual species can then be tracked. Common trends for the inhabitants of certain habitats can also be identified.

This is precisely the idea behind the Butterfly Grassland Indicator, which is based on the population trends of 17 typical species of meadows and pastures. If the positive and negative trends in these species roughly balance each other out, the indicator remains at the same level. If more species decline than increase in the same period, the value decreases -- and vice versa. Lower values thus indicate greater problems among grassland dwellers.

The latest results of these calculations, which include data from 1990 to 2020, therefore do not bode well. The analysis, which was also co-financed by the EU project SPRING (Strengthening Pollinator Recovery through Indicators and monitoring) coordinated by the UFZ, shows only one winner: In the 27 memberstates of the EU, only the Orange Tip (Anthocharis cardamines) displayed a moderate increase. Three species are stable: the Large Skipper (Ochlodes sylvanus), the Common Copper (Lycaena phlaeas), and the Meadow Brown (Maniola jurtina). Five species -- from the Common Blue (Polyommatus icarus) to the Wall Brown (Lasiommata megera) -- are showing declining populations. "The biggest loser in recent years has been the large blue (Phengaris arion), which for example has disappeared completely in the Netherlands," says Settele. For the remaining species of the 17 grassland inhabitants studied, there is either no clear trend or too little data.

The picture becomes even less favourable if we look not only at the EU but rather at Europe as a whole. Then there are no species on the rise and only three are stable. Six show a moderate and one even a strong decline.

In view of these developments, it is not surprising that the grassland indicator is now at a considerably lower level than before. In the last 10 years alone, the calculated value for the EU has fallen by 32% -- and that for Europe as a whole by as much as 36%. The crisis of the grassland dwellers has apparently already taken hold of the entire continent. This is becoming increasingly more evident the more information is provided by the volunteer butterfly counters from different countries. "The declines are not confined to north-western Europe," says Chris van Swaay of Butterfly Conservation Europe. "However, some species in the South and East are doing much better."

He and his colleagues attribute the dwindling butterfly occurrences mainly to changes in agriculture. In north-western Europe, for example, the over-intensive use of meadows and pastures has a particularly unfavourable effect. The heavy use of fertilisers often also pollutes adjacent protected areas with excessive amounts of nitrogen. In the rest of Europe, the main problem is the complete abandonment of cultivation. That's because grassland butterflies also cope poorly with this.

Read more at Science Daily

Less intensively managed grasslands have higher plant diversity and better soil health

Researchers have shown -- for the first time -- that less intensively managed British grazed grasslands have on average 50% more plant species and better soil health than intensively managed grassland. The new study could help farmers increase both biodiversity and soil health, including the amount of carbon in the soil of the British countryside.

Grazed grassland makes up a large proportion of the British countryside and is vital to farming and rural communities. This land can be perceived as only being about food production, but this study gives more evidence that it could be key to increasing biodiversity and soil health.

Researchers at the UK Centre for Ecology & Hydrology (UKCEH) studied 940 plots of grassland, comparing randomly selected plots which sampled the range of grassland management across Great Britain; from intensively- managed land with a few sown grassland species and high levels of soil phosphorus (indicating ploughing/reseeding and fertiliser and slurry application), to grassland with higher levels of species and lower levels of soil phosphorus. The plots were sampled as part of the UKCEH Countryside Survey, a nationally representative long-term dataset.

The study counted the number of plant species in sample areas and analysed co-located soil samples for numbers of soil invertebrates and carbon, nitrogen and phosphorus levels.

Researchers found that less intensively managed grassland had greater diversity of plant species and, strikingly, this correlated with better soil health, such as increased nitrogen and carbon levels and increased numbers of soil invertebrates such as springtails and mites.

In the same study, the researchers used the same methods to examine the plant diversity and soil from grasslands on 56 mostly beef farms from the Pasture Fed Livestock Association (PFLA) -- a farmer group that has developed standards to manage and improve soil and pasture health.

The researchers found that plots of land from PFLA farms had greater plant diversity -- on average an additional six plant species, including different types of grasses and herbaceous flowering plants, compared to intensively farmed plots from the Countryside Survey. In addition, grassland plants on these farms were often taller, a quality which is proven to be beneficial to butterflies and bees.

Pasture Fed Livestock Association grasslands did not yet show increased soil health, but the research indicated that this may be due to a time lag between increasing numbers of plant species and changes in soil health, particularly on farms which have been intensively managed in the past.

Lead author Dr Lisa Norton, Senior Scientist at UKCEH, says: "We've shown for the first time, on land managed by farmers for production, that a higher diversity of plants in grasslands is correlated with better soil health. This work also tells us that the Pasture Fed Livestock Association members are on the right track to increase biodiversity, though it may take longer to see improvements in soil health.

"Grassland with different types of plants able to grow tall and flower is associated with improved soil health measures, and is beneficial for creepy crawlies below and above ground. Having this abundance of life in our grasslands can in turn support small mammals and birds of prey, and farmers have told us that they are seeing voles and mice in their fields for the first time."

Dr Norton adds: "My hope for the future is that our grasslands can be managed less intensively -- with all the improvements in plant and animal biodiversity and soil health that brings -- but still remain productive for farmers."

Read more at Science Daily

Oft-overlooked grasslands build biodiversity, resilience over centuries

Grasslands' biodiversity and resilience to disturbances such as fire, heat and drought is the result of a slow process over hundreds of years, like that of old growth forests, finds new University of Colorado Boulder-led research.

Publishing in the journal Science on Aug. 5, 2022, as part of a special issue on grasslands, the study contradicts years of assumptions that grasslands' ecological development is quick and their recovery is rapid, posing new challenges to their successful restoration.

"Old growth grasslands have a unique suite of characteristics that develop over a really long time. Recovering grasslands do not have the same species or the same characteristics as they did prior to soil tilling or tree planting, and they take centuries to redevelop," said Katharine Suding, senior author of the paper and Distinguished Professor in the Department of Ecology and Evolutionary Biology and Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder. "It's an important reminder that we need to conserve the ancient grasslands that are still intact."

An expert in the field of North American grasslands, Suding partnered with other experts from around the world to evaluate the current state of global grassland science, conservation and restoration -- from arid, prairie and coastal grasslands, to those in the tropics and savannahs.

Grasslands, which account for nearly 40% of land-based ecosystems, provide habitat for a wide diversity of animals and plants, and contribute to the livelihoods of over 1 billion people worldwide. They also provide significant carbon sequestration and biodiversity benefits, and can be more resilient than forests in the face of a quickly changing climate.

Yet over the past couple of centuries, ancient grasslands around the world have largely been converted into farmland, used to grow trees or been developed as cities expand.

The researchers found that while the destruction of these pristine grasslands can occur very quickly, complete recovery of grassland biodiversity and essential ecosystem functions occurs slowly or not at all. The findings further emphasize the importance of conserving the world's remaining untouched grasslands.

"If you plant trees in an older grassland or till it for agriculture, you will probably never get many of the unique diversity and belowground characteristics back. It is irreversible," said Suding.

Restoration takes time

Grasslands store the bulk of their material underground, in roots that can reach as far as 20 feet deep. This unseen physical presence is how they can store a lot of carbon -- about a third of all carbon stored on land -- and remain resilient to fire and other ecological disturbances. It's also why grasslands are often underappreciated in comparison to forests. If it's out of sight, it's out of mind.

Grassland restoration, however, can take a page out of forests' playbook.

"'Old growth' is not only a term for forests, but one that applies to grasslands as well," said co-author Elise Buisson, who co-authored that finding in a 2015 publication.

Old growth grasslands are unique in their underground structures and biodiversity compared to newer, younger grasslands. And while these old growth ecosystems may never be fully replicated in modern-day landscapes, they provide a model for restoration efforts, said Suding.

Even a decade ago, grassland restoration focused on distributing species' seed onto a landscape, adding grazing or fire, and stepping aside. The new analysis finds that it takes more than a hands-off approach to be successful. Instead of tossing all the ingredients into a crockpot and turning it on high, grasslands may need more of a step-by-step recipe approach to restoration.

"We should think of restoration as more of guiding a trajectory. Some species don't come in right at the start, and the disturbance that maintains the grassland needs time to grow and be tweaked as these species get established and the soil develops," said Suding. "These processes take time."

For example, some plants do well reproducing from seed in, say, the upper Midwest but not in Colorado due to the drier climate. Many tropical grasses don't spread by seed at all, instead by rhizomes and tubers underground, and are much more difficult to reestablish.

Implications for policy

The report comes a year after the start of the United Nations Decade on Ecosystem Restoration, which aims to restore degraded ecosystems around the world to increase biodiversity, help achieve the Sustainable Development Goals and the Paris Climate Agreement. At the same time, planting trees has become a popular "natural solution" around the world to remove large quantities of carbon from the atmosphere.

Yet while the UN initiative explicitly states, "planting trees on natural grassland may destroy more than it creates," as countries make ambitious goals and commitments to ecosystem restoration this decade, Suding worries that for many, this only means planting trees.

"We would lose a huge element of the biodiversity on Earth if we planted trees in old growth grasslands," said Suding. "I think we need to be a little bit more careful about what's best for the globe, in terms of where to restore what."

As climate change threatens the American West through drought, heat and wildfire, grasslands are also a resilient choice to use less water, reduce soil erosion and keep carbon in the ground over time. It's the older, veteran grasslands that are most beneficial in this regard.

Read more at Science Daily

Fossil elephant cranium reveals key adaptations that enabled its species to thrive as grasslands spread across eastern Africa

A remarkably well-preserved fossil elephant cranium from Kenya is helping scientists understand how its species became the dominant elephant in eastern Africa several million years ago, a time when a cooler, drier climate allowed grasslands to spread and when habitually bipedal human ancestors first appeared on the landscape.

Dated to 4.5 million years ago and recovered from a site on the northeast side of Lake Turkana, it is the only well-preserved elephant cranium -- the portion of the skull that encloses the brain -- from that time. It isabout 85% intact and holds a wealth of previously unavailable anatomical detail, according to University of Michigan paleontologist William Sanders.

Known by its museum number, KNM-ER 63642, the roughly 2-ton cranium belonged to a massive adult male of the species Loxodonta adaurora, an extinct evolutionary cousin of modern African elephants but not a direct ancestor.

KNM-ER 63642 is both impressively immense and unexpectedly modern in aspect, displaying adaptations that likely gave L. adaurora an edge when competing with other large mammals for grasses, according to Sanders, lead author of a study published online Oct. 21 in the journal Palaeovertebrata. Co-authors include Meave and Louise Leakey, who led the recovery effort and who are best known for the discovery of early hominid specimens and artifacts from Lake Turkana and elsewhere.

The L. adaurora cranium is striking because it is raised and compressed from front to back, suggesting a novel alignment of chewing muscles well-suited for the efficient shearing of grasses. In addition, the animal's molars are higher-crowned and had thicker coatings of cementum than other early elephants, making the teeth more resistant to the wear common in animals that feed on grasses close to the ground.

"The evident synchronization of morphological adaptations and feeding behavior revealed by this study of Loxodonta adaurora may explain why it became the dominant elephant species of the early Pliocene," said Sanders, who has studied fossil elephants and their relatives for nearly 40 years in Africa and Arabia.

Eastern Africa was home to seven or eight known species of early elephants at the time, along with horses, antelope, rhinos, pigs and hippos. Many of these animals were becoming grazers and competing for the available grasses.

"The adaptations of L. adaurora put it at a great advantage over more primitive elephants, in that it could probably use less energy to chew more food and live longer to have more offspring," said Sanders, associate research scientist at the U-M Museum of Paleontology and in the Department of Anthropology.

Recovery, conservation, dating, description and identification of the elephant cranium involved collaborative work between researchers and techniciansfrom the Turkana Basin Institute, National Museums of Kenya, University of Michigan, Rutgers University, Smithsonian Institution and University of Utah.

KNM-ER 63642 was discovered in 2013 by a member of the Koobi Fora Research Project from a single molar that was visible at the surface.

Excavation revealed the presence of a nearly complete cranium. The tusks and the jawbone were missing, and no other remains from that individual were recovered. The adult male is estimated to have been 30 to 34 years old at death.

The fossilized cranium, together with the plaster jacket that protected it and some attached sediment, weighed about 2 tons. Based on a previous study of the skeleton from another L. adaurora adult male with a similar-sized skull, this individual likely weighed about 9 tons and probably stood about 12 feet at the shoulder -- bigger than average male elephants of modern times.

"In my opinion, this elephant skull is by far the most impressive specimen that we have in the Kenyan paleontological collection from Lake Turkana, both in its completeness and in its size," said paleontologist and study co-author Louise Leakey of the Koobi Fora Research Project. "When the teeth were seen on the surface, we had no idea that a complete cranium would be uncovered, and the excavation and recovery operation was both challenging and exciting."

KNM-ER 63642 is now permanently housed at the Turkana Basin Institute's facility in Ileret, Kenya. It is the only well-preserved elephant cranium from the interval beginning with the origin of elephants 8 million years ago and ending 3.5 million years ago, according to Sanders.

In addition to providing a trove of insights about the anatomy of early elephants, the newly described cranium also deepens our understanding of the connections between those creatures and our earliest human ancestors, the habitually bipedal australopithecines.

Loxodonta adaurora and other early elephants coexisted with two well-known australopithecine species in eastern Africa: Australopithecusanamensis, recovered by Meave Leakey in and nearby the Lake Turkana Basin, Kenya, and A. afarensis, found at sites in Hadar, Ethiopia, and Laetoli, Tanzania.

In the early Pliocene, as grassy woodlands and grasslands spread across eastern Africa, the australopithecines would have benefited from the presence of elephants. The animals' feeding activities helped keep grasses low to the ground, which would have allowed our upright ancestors to see over the vegetation and to watch for predators.

Elephants also disrupt closed woodlands and create open areas by knocking over trees, uprooting shrubs, and trampling paths through dense forest. And they spread nutrients and grass seed in their dung.

"The origins and early successes of our own biological family are tied to elephants," Sanders said. "Their presence on the landscape created more open conditions that favored the activities and adaptations of our first bipedal hominin ancestors.

"From this perspective, it is ironically tragic that current human activities of encroaching land use, poaching and human-driven climate change are now threatening the extinction of the mammal lineage that helped us to begin our own evolutionary journey."

Read more at Science Daily