Showing posts with label biodiversity. Show all posts
Showing posts with label biodiversity. Show all posts

Saturday, March 21, 2020

Why Honey bees aren’t the buzz

*Guest post by Shannon Underwood, a student in Marc's 'Causes and Consequences of Diversity' class.

When you think “Save the Bees”, most likely a Honeybee comes to mind – this is primarily because they have become the flagship species for the current bee crisis. Although responsible for bringing the much-needed attention to the impact humans are having on our bee populations, they greatly misdirect the public, making a large number of people significantly less aware of the other 4,000 diverse bee species we have in North America14 – our wild (native) bees: the ones we should be more concerned about.

Fig 1. Adapted from Wilson, Forister, and Carril 2017. Above figure shows the total amount of bee species survey-participants thought were in the United States.
Pollinators are responsible for supporting 35% of the global agricultural landscapes15. Outside of agriculture, 80-95% of the native flowering plants that are found in natural ecosystems rely on animal pollinators for reproduction11. Pollination is a fundamental ecosystem service provided by a variety of animals, however most efficiently by wild bees. The unique evolutionary histories that bees share with native plants has resulted in the vast diversity of traits seen among them (Photo 1), and communities with greater bee diversity have shown to be more productive than communities with poorer diversity12 - largely because of greater resource partitioning by the wild bees. Their foraging preferences, differences in body shapes and sizes, as well as some species ability to perform a more effective technique of pollination called buzz pollination, make wild bees the most important group of pollinators.


 Photo 1: Shows the different body shapes and sizes of some wild bees. This rich diversity reflects their unique coevolution with plants.

Bees are facing substantial reductions in their diversity, range and abundances worldwide1. In North America, there are currently 12 wild bee species that are recognized as ‘threatened’ under the IUCN Red-list. Staggeringly, all 12 of these species belong to the genus Bombus- commonly referred to as the Bumblebee. Over that last 20 years, Bumblebees have become one of the largest victims of decline in North America - with four species that faced a 23-87% shrinkage in their geographic range, and a precipitous 96% reduction in their abundance2. A leading cause of the declines in wild bee populations has been largely attributed to land-use change1. While the human population continues to expand, accumulating amounts of their natural habitat is lost and replaced with agricultural and urban landscapes. The fragmented habitats that remain often have decreased accessibility to green spaces and poorer nesting opportunities for bees. Making it harder for them to grab a foothold in the community – these human-added stressors put our wild bees at a much greater risk for extinction.

Fig 3. Adapted from Szabo et al. 2012. Shows the decline in the occurrence of B. affinis (A)B. terricola (B), B. pensylvanicus (C), and all bumblebee species (D) between the years of 1980-1990 (green) and 2000-2010 (blue).

The second most prominent impact on wild bee abundance and diversity has been greatly linked to invasive species like the common Western Honey bee1. The Honeybee, native to the Old World region, has become an invasive species in all areas outside of its origin3. Their uniquely large colonies and hive formation make them the most valuable pollinator to humans in agriculture management. Wild bee health and productivity is often reduced in agricultural landscapes because of the high use of pesticides and lower foraging opportunities7. To compensate for this, the honeybee has become a highly used technique worldwide because they can be easily transported to a field for crop pollination- many policies and conservation efforts tend to primarily focus on the protection of such managed bee species because of this. But the positive attention that the honeybee receives publicly leaves many people unaware that it is even invasive in North America.

Honeybees are generalists – a common characteristic for many invasive species8. They can forage up to 2-3km outside of their hive and will recruit other colony-workers once a good food source is found, in order to maximize their foraging products3. Because of their large numbers, they can greatly increase the foraging competition for our already-threatened wild bee species. Honeybees are also prone to several diseases and can increase the risk of transmission to our wild bee populations3. Although the honeybee is valuable in agricultural pollination for its cost and time efficiency, in many cases wild pollinators are better at pollinating than the honeybee alone (Fig. 4). The honeybee lacks the ability to perform buzz pollination - the amount of pollen a queen Bumblebee can deposit to a blueberry flower in a single visit would require a honeybee to visit the same flower 4 times9. These small and diverse organisms are thus extremely important for sustaining healthy natural ecosystems, and so it becomes increasingly significant that we find ways to support their abundance and diversity during this new human-dominated era.

Fig. 4. Adapted from Garibaldi et al. 2013. The figure shows that wild insects increased reproduction (y-axis) in all crops examined than the honeybee alone.

Cities are commonly viewed as human-dominated landscapes that are inhabitable for wildlife. However, some people argue that cities may actually be ecologically valuable to certain types of species like our insect-pollinators7. Cities often have less pesticide than the surrounding rural landscapes7, and the commonly used green infrastructures like green roofs, gardens, and parks can be extremely valuable to pollinators by offering more abundant and diverse foraging opportunities. Green infrastructure in cities is also recognized as being important for decreasing flight times and even providing habitat for certain species4. Many beekeepers highlight that one of the best things anyone can do to support wild bees is to transform their property into a bee sanctuary. Plant pollinator-friendly gardens and even incorporate bee hotels into your backyard as a way to offer wild bees more opportunities in developed areas. You can also take part in projects like “Bees In My Backyard”  and “Bumble Bee watch”  to help conservationists collect information on our current bee populations. More importantly, though, just becoming educated about the threats to our wild bees and spreading awareness to the people around you is a crucial step towards refocusing our pollinator conservation efforts, and bringing the attention away from the honeybee and rightfully onto our wild bees.

Literature cited

1.     Brown, Mark J. F., and Robert J. Paxton. 2009. “The Conservation of Bees: A Global Perspective.” Apidologie 40(3): 410–16.

2.     Cameron, Sydney A. et al. 2011. “Patterns of Widespread Decline in North American Bumble Bees.” Proceedings of the National Academy of Sciences 108(2): 662–67.

3.     Colla, Sheila R., and J. Scott MacIvor. 2017. “Questioning Public Perception, Conservation Policy, and Recovery Actions for Honeybees in North America.” Conservation Biology 31(5): 1202–4.

4.     Dylewski, Łukasz, Łukasz Maćkowiak, and Weronika Banaszak‐Cibicka. 2019. “Are All Urban Green Spaces a Favourable Habitat for Pollinator Communities? Bees, Butterflies and Hoverflies in Different Urban Green Areas.” Ecological Entomology 44(5): 678–89.

5.     Garibaldi, Lucas A. et al. 2013. “Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance.” Science 339(6127): 1608–11.

6.     Graham, Kelsey K. “Beyond Honey Bees: Wild Bees Are Also Key Pollinators, and Some Species Are Disappearing.” The Conversation. (February 20, 2020).

7.     Hall, Damon M. et al. 2017. “The city as a refuge for insect pollinators.” Conservation Biology 31(1): 24–29.

8.     “Invasive Species | U.S. Climate Resilience Toolkit.” (February 21, 2020).

9.     Javorek, S. K., K. E. Mackenzie, and S. P. Vander Kloet. 2002. “Comparative Pollination Effectiveness Among Bees (Hymenoptera: Apoidea) on Lowbush Blueberry (Ericaceae: Vaccinium Angustifolium).” Annals of the Entomological Society of America 95(3): 345–51.

10.  Matias, Denise Margaret S. et al. 2017. “A Review of Ecosystem Service Benefits from Wild Bees across Social Contexts.” Ambio 46(4): 456–67.

11.  Ollerton J, Winfree R, Tarrant S: How many flowering plants are pollinated by animals? Oikos 2011, 120(3):321-326.

12.  Rogers, Shelley R., David R. Tarpy, and Hannah J. Burrack. 2014. “Bee Species Diversity Enhances Productivity and Stability in a Perennial Crop.” PLOS ONE 9(5): e97307.

13.  Szabo, Nora D. et al. 2012. “Do Pathogen Spillover, Pesticide Use, or Habitat Loss Explain Recent North American Bumblebee Declines?” Conservation Letters 5(3): 232–39.

14.  “The IUCN Red List of Threatened Species.” IUCN Red List of Threatened Species. (February 20, 2020).

15.  “What Are Pollinators and Why Do We Need Them? (Center for Pollinator Research).” Center for Pollinator Research (Penn State University). (February 21, 2020).

16.  “Why bees matter.” Food and Agriculture Organization of the United Nations. 2018.

17.  Wilson, Joseph S., Matthew L. Forister, and Olivia Messinger Carril. 2017. “Interest Exceeds Understanding in Public Support of Bee Conservation.” Frontiers in Ecology and the Environment 15(8): 460–66.

Monday, March 9, 2020

The “man” in mangroves: How does the Anthropocene impact biodiversity in these ecosystems?

 *This post is by Nina Adamo, a student in Marc's 'Causes and COnsequences of Diversity' class.

Mangroves are among the most biologically important forest ecosystems on Earth, found in the intertidal zone between land and sea along tropical and subtropical coasts around the world.7 Mangrove ecosystems provide habitat for a wide range of terrestrial as well as aquatic organisms including plants, fish, mollusks, birds, reptiles, and crustaceans, among many others.1

Mangroves also serve as nursery habitats for various fish and crab species found in coastal regions, as mangroves provide high abundances of food and shelter for developing wildlife living in coastal regions.7 Since many species use mangroves as nursery grounds, fish diversity and abundance in neighbouring coastal ecosystems has been positively linked to the proximity of mangrove areas, suggesting that mangrove habitat is critical in supporting biodiversity in surrounding coastal ecosystems.5

Figure 1: Many species such as fish and crustaceans use mangroves as a nursery site for their young, where shelter from predators and food is abundant.9

Along with supporting a wide range of biodiversity along coastal ecosystems, mangroves also provide many essential ecosystem services to humans. Some of these societal benefits include natural resources such as fish and timber, coastal protection from storms, and assisting in mitigating climate change by removing carbon dioxide from the atmosphere and storing it.11
Despite the critical role mangroves play in supporting coastal biodiversity and providing ecosystem services to society, mangroves have been disappearing globally at an alarming rate of 1-2% per year due to anthropogenic activities and accelerated global climate change.4 The main threats to these ecosystems are rising sea levels causing coastal erosion, environmental condition changes due to climate change, land-use changes, deforestation, and overexploitation of natural resources.4 This has led to the loss of about 50% of mangrove coverage across the globe since 1950.10

In recent years, there have been a great number of studies that have explored the impacts of anthropogenic activities and climate change on the biodiversity of vegetation, benthic meiofauna, and benthic fauna found in mangrove ecosystems.

Figure 2: A stilt mangrove tree in a mangrove forest coastal ecosystem on an island in East Kalimantan, Indonesia.8

In the Sundarbans, which is the world’s largest remaining natural mangrove ecosystem located on the border of Bangladesh and India, there has been a homogenization of tree species composition over the span of 28 years from the 1980s to the 2010s.10 In other words, the largest remaining mangrove ecosystem has experienced a loss in community biodiversity of mangrove plant species over time due to anthropogenic activities and the environmental impact of climate change.

The loss of biodiversity in ecosystems is a crucial issue because higher biodiversity in most ecosystems typically leads to higher ecosystem functioning, so if biodiversity is lost through stressors such as habitat loss or extreme environmental conditions such as those produced through global climate change, it could have severe impacts on the diversity of an ecosystem and hence the functioning of the ecosystem as a whole.2

The biodiversity of benthic meiofauna, which are very small invertebrates that live in the bottom of aquatic mangrove ecosystems, are also negatively impacted by anthropogenic disturbances. In a comparison study of disturbed and undisturbed mangrove areas, disturbed areas displayed a 20% loss of benthic meiofauna biodiversity compared to undisturbed mangrove areas.2 Since many juvenile fish species that use mangrove ecosystems as nursery grounds rely heavily on meiofauna for food, this loss of biodiversity through anthropogenic causes could cause a reduction in ecosystem functioning not only within mangrove communities but in surrounding coastal ecosystems as well.2

A similar observation is also found with the biodiversity of benthic fauna in mangrove ecosystems in the Philippines, where protected mangrove ecosystems have significantly higher diversity and abundance of crab species than reforested mangrove ecosystems that have been disturbed by humans.1 This suggests that environmental factors influenced by climate change and human influences in mangrove ecosystems can have a negative impact on the biodiversity of benthic fauna, one of the most dominant groups in these systems, which could impair the overall functioning of the ecosystem.1

With the increasing loss of mangrove habitat and the biodiversity within it across the globe due to anthropogenic activities and climate change, it is essential that humans intervene with utilizing other paradigms such as the flagship species paradigm to increase mangrove conservation and policies to protect mangrove habitat,11 well-researched and well-managed mangrove planting restoration,6 and more research on innovative manmade artificial mangroves that may help to restore these ecosystems.3

Figure 3: Locations of the various megafauna found in mangroves (locations of mangrove areas shown in green) around the globe, with the orange representing terrestrial and the blue representing aquatic megafauna. Some examples of megafauna found in mangroves (from top-left to bottom-left in a clockwise direction) include the Key deer, Manatee, Sailfin lizard, Sawfish, Three-toed sloth, Spotted deer, Bengal tiger, Otter, Green turtle, Crocodile, and the Proboscis monkey.11

The focus of much of the recent research on mangrove conservation has utilized an ecosystem services approach, where the benefits that mangroves provide to humans is stressed as an incentive for conservation.11 For this reason, most of the research has been focused on smaller benthic invertebrates such as crabs and shrimp, rather than larger charismatic megafauna that are found in mangroves around the world such as sloths, Bengal tigers, green turtles, and proboscis monkeys.11

Conservation awareness of mangrove ecosystems could be improved by using the flagship species paradigm which uses larger charismatic species found in mangrove ecosystems in marketing campaigns that would protect the entire ecosystem in which they are found. Since charismatic megafauna have been observed in mangrove habitats across the globe, using the flagship species paradigm in conjunction with the ecosystem services paradigm could increase public awareness of the threats facing these extremely diverse and productive ecosystems.11

Conserving mangrove ecosystems around the world is important as these ecosystems provide ecosystem services to human society and play a critical role in supporting biodiversity within mangrove systems and in neighbouring coastal systems. With the increasing threat of anthropogenic activities and global climate change, the conservation and protection of mangroves is essential to reduce the decline in ecosystem functioning and biodiversity in these ecologically important ecosystems that many animals and humans alike rely on in order to live productive and successful lives.


1.     Bandibas, M. B., & Hilomen, V. V. (2016). Crab biodiversity under different management schemes of mangrove ecosystems. Global Journal of Environmental Science and Management, 2(1), 19–30.

2.     Carugati, L., Gatto, B., Rastelli, E., Lo Martire, M., Coral, C., Greco, S., & Danovaro, R. (2018). Impact of mangrove forests degradation on biodiversity and ecosystem functioning. Scientific Reports, 8(1), 1–11.

3.     Florida Atlantic University. (2018). Humanmade mangroves could get to the “root” of the problem for threats to coastal areas. ScienceDaily. Retrieved February 20, 2020, from

4.     Hapsari, K. A., Jennerjahn, T. C., Lukas, M. C., Karius, V., & Behling, H. (2019). Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove-fringed coastal lagoon in Java, Indonesia. Global Change Biology.

5.     Henderson, C. J., Gilby, B. L., Schlacher, T. A., Connolly, R. M., Sheaves, M., Flint, N., Borland, H. P., & Olds, A. D. (2019). Contrasting effects of mangroves and armoured shorelines on fish assemblages in tropical estuarine seascapes. Ices Journal of Marine Science, 76(4), 1052–1061.

6.     Kodikara, K. A. S., Mukherjee, N., Jayatissa, L. P., DahdouhGuebas, F., & Koedam, N. (2017). Have mangrove restoration projects worked? An in-depth study in Sri Lanka. Restoration Ecology, 25(5), 705–716.

7.     Nagelkerken, I., Blaber, S. J. M., Bouillon, S., Green, P., Haywood, M., Kirton, L. G., Meynecke, J.-O., Pawlik, J., Penrose, H. M., Sasekumar, A., & Somerfield, P. J. (2008). The habitat function of mangroves for terrestrial and marine fauna: A review. Aquatic Botany, 89(2), 155–185.

8.     Rante, A. (2019, December 12). A stilt mangrove tree in a protected area on Semama Island in East Kalimantan. Supertrees: Meet Indonesia’s mangrove, the tree that stores carbon. [Image].Vox. Retrieved February 20, 2020 from

9.     Rante, A. (2019, December 12). In the water lapping at mangrove roots, young fish and plankton take refuge from predators. Supertrees: Meet Indonesia’s mangrove, the tree that stores carbon. [Image].Vox. Retrieved February 20, 2020 from

10.  Sarker, S. K., Matthiopoulos, J., Mitchell, S. N., Ahmed, Z. U., Mamun, Md. B. A., & Reeve, R. (2019). 1980s–2010s: The world’s largest mangrove ecosystem is becoming homogeneous. Biological Conservation, 236, 79–91.

11.  Thompson, B. S., & Rog, S. M. (2019). Beyond ecosystem services: Using charismatic megafauna as flagship species for mangrove forest conservation. Environmental Science & Policy, 102, 9–17.

Friday, November 30, 2018

Un-BEE-lievable: The Buzz on Native Bee Conservation in Canada

Guest post by University of Toronto-Scarborough MEnvSc Candidate Rachel Siblock

Unless you’ve been living under a rock (much like native mining bees in Canada), you’ve probably seen the numerous campaigns to “Save the Bees”. Bee species across the globe are in decline. There are many factors that contribute to this decline, such as pesticide use, colony collapse, disease, habitat loss, and climate change1. Many of these factors interact with one another, exacerbating the consequences and impacts. Conservation efforts are being implemented to try to stop the loss of these pollinators, and the valuable services they provide to humans. Canada is no exception. There are local, provincial, and national policies and programs operating and currently being developed in order to reduce the impacts of these threats. In the past few years, programs like The Bee Cause, Bees Matter, Feed the Bees, and others have implemented programs and recommendations in order to increase the bee populations in Canada. Honey Nut Cheerios has even campaigned to get the public engaged and involved in the conservation of bees. These programs, however, all have one common issue: they focus their efforts on Honey Bees. 

An example of a campaign by Honey Nut Cheerios, focusing on honey bees. 
There are no native honey bees in Canada. The most well-known bee in Canada was not even present in the country until it was introduced from Europe in the 1600s2. The European Honey Bee was intentionally introduced to Canada for honey production, and since has increased in number dramatically, both in farmed and wild colonies. Honey bees have large colonies, allowing them to be easily managed and farmed. They also pollinate crops and produce honey, which may make them seem more economically valuable than their native, non-honey-producing counterparts. However, there have been unexpected impacts of the introduction of the European Honey Bee on native bee species in Canada.
            There are over 800 native bee species in Canada. While there are many different types of bees in Canada, the best understood group of native bees are bumble bees. Bumble bees have the ability to buzz pollinate, which allows them to obtain pollen from plants with pollen that is difficult to extract. Many of these plants are economically valuable, such as kiwi and blueberry crops. This, along with general pollination, makes managed populations of bumble bees worth several billion dollars annually3. Bumble bees naturally have low genetic diversity and can be subject to inbreeding depression, leading to declining populations and making the some species more vulnerable to extinction4. Threats can then interact with these low population levels, and intensify population loss. 
A male Rusty-patched Bumble Bee, one of Canada’s native bee species. It is currently listed as endangered in Canada.
Aside from facing the same threats as honey bees, native bumble bees are also threatened by the very presence of honey bees. Competition for resources with honey bees is a major threat to native bumble bees. A study performed in the United Kingdom found that bumble bees at sites with high honey bee density were significantly smaller in body size when compared to their relatives at sites with low honey bee density5. An additional study discovered a reduction of native bumble bee colony success when colonies were experimentally exposed to honey bees6. Honey bees generally produce larger colony sizes which can store a larger amount of resources than bumble bees. They also have the ability to communicate with one another about valuable floral resource locations7. Honey bees have a larger foraging range than native bumble bees, and have an increased ability to forage on introduced plant species7. These adaptations allow honey bees to outcompete native bumble bees, and commandeer sparse resources in the area.
            Threats from honey bees do not just end at competition; pathogens and parasites specifically adapted to honey bees have been shown to have the ability to spread to wild bumble bee populations. Managed honey bees are known to carry higher than natural levels of pathogens8, which can be transmitted to wild bumble bee populations when the bees interact. In particular, two pathogens endemic to honey bees, C. bombi and N. bombi, are wreaking havoc on bumble bee populations. While these pathogens do not have lethal effects, their sublethal effects can be devastating to colonies. These pathogens cause reduced pollen loads, a decline in flowers visited per minute, slower growth rates of colonies, decreased queen reproductive rates, shortened life spans and diminished colony growth8. With small populations already, entire bumble bee colonies can be wiped out by these pathogens. Honey bee parasites, such as the Small Hive Beetle, have also been shown to be able to spread to bumble bee colonies, where they consume the wax, pollen, and nectar stores of hives8. While honey bees have co-evolved with these parasites and pathogens for eons, bumble bees have not had the time to adapt to these threats, making them much more vulnerable to these hazards. 
Small Hive Beetle infestation in a honey bee colony. 
But why do we care about losing native bees? The same concerns about the loss of honey bees applies to native bees. Native bee species pollinate crops and flowers, which we depend on for food. It is estimated that about one in three bites of food we consume can be traced back directly to pollination by bees and other pollinators. However, native bees have been found to be more effective pollinators than honey bees. Some plant species in Canada rely solely on native bees for their pollination. With the loss of native bees, these plants will also become endangered, along with many other food crops requiring pollination. Additionally, there is a severe lack of research into native bees. Research tends to focus on honey bee populations, resulting in much more knowledge of honey bee behaviours, adaptations, actions, and responses to stressors. The truth is, we don’t know much about native bee species in Canada. We have no idea what the consequences of the loss of these species will be. However, this does not excuse us from protecting these bees. If anything, this lack of knowledge should increase our urge to protect them, so we have the opportunity to learn about them in the future.
            The native bee species in Canada share little life history traits with the European Honey Bee8, making many conservation efforts that focus on honey bees unsuccessful. Focusing conservation efforts on one species may not address the specific needs of native bees. In addition, by focusing on improving honey bee populations, there will be increased stress on native bees, which will lead to a decline in their populations. If we continue with these conservation strategies, we may threaten native species further.
            An increase in honey bee populations will increase parasite and pathogen levels in native bees, and also increase the competition between honey bees and native bees. So what can you do to focus conservation efforts on native Canadian bees? For starters, avoid the use of pesticides, which will decrease already low populations8. Improve your knowledge of bee species, and report invasive or introduced species in areas used by native bee species. Plant a wide variety of native plants with high pollen and nectar concentrations to ensure newly emerging bees have the resources they need to survive. And finally, avoid tilling, mowing, or burning in areas where native bee species, particularly ground dwelling species, are known to live. With increased knowledge of native bee needs, and species specific conservation efforts, it is hoped that native bee species will begin to rebound. Let’s BEE positive!

BEE Informed – To get involved with native bee conservation check out these links:

    1.     Pettis, J.S., and K.S. Delaplane. 2010. Coordinated responses to honey bee decline in the USA. Adipologie 41:256-263.
    2.     van Engelsdorp, D., and M.D. Meixner. 2010. A historical review of managed honey bee populations in Europe and the United Sates and the factors that may affect them. Journal of Invertebrate Pathology 103:80-95.    
    3.     James, R., and T.L. Pitts-Singer. 2008. Bee Pollination in Agricultural Ecosystems. Oxford University Press, USA.
    4.     Zayed, A., and L. Packer. 2005. Complementary sex determination substantially increases extinction proneness of haplodiploid populations. Proceedings of the National Academy of Sciences of the United States of America 102:10742-10746.
    5.     Goulson, D., and K. Sparrow. 2009. Evidence for competition between honey bees and bumble bees: Effects on bumble bee worker size. Journal of Insect Conservation 13:177-181.
    6.     Thomson, D. 2004. Competitive interactions between the invasive European honey bee and native bumble bees. Ecology 85:458-470.
    7.     Goulson, D. 2003. Effects of introduced bees on native ecosystems. Annual Review of Ecology, Evolution, and Systematics 34:1-26.
    8.     Colla, S.R. 2016. Status, threats and conservation recommendations for wild bumble bees (Bombus spp.) in Ontario, Canada: a review for policymakers and practitioners. Natural Areas Journal 36:412-426.

Image Sources:

Wednesday, November 21, 2018

Tea Time with Amazigh People

Guest post by University of Toronto-Scarborough MEnvSc Candidate Erin Jankovich

 “How do they survive?” This is the question I kept asking myself over and over as I sat sipping my mint tea on the clay floor of an Amazigh cave in the Moroccan mountains. Their faces, hands, tea-kettle and even my cup were layered with dirt and soot. Outside, prevailing winds dusted the lonely peaks of the High Atlas with orange silt. I never expected to stumble across an indigenous settlement when I set out on my hike that day, let alone be invited for tea. This was by no means a fancy tea party, but it certainly was a memorable one.

Women plucked leaves from dry aromatic plants and a man filled a kettle for more tea. A toddler sat beside me and gestured to trade his clay ball for my Nikon. I felt like a fly on the wall in a National Geographic documentary.

I was on to my third cup of tea when a young man broke the silence. “Hello, do you speak English”, I heard from behind me. Dressed in traditional Amazigh clothes, this young man carrying a notepad and pen excitedly sat down beside me. He was a university student from Japan who had been living with this Amazigh family for four months to learn about their culture. Perfect! Maybe he could enlighten me as to how these people sustain their lives on this rugged mountain top - surely there was more to it than mint tea.

Mint tea, a traditional Moroccan drink and symbol of hospitality. Photography: Erin Jankovich

The young man pointed out across the valley and said “see”. For a while, all I saw was an expanse of orange rock but eventually like a stereogram the landscape came to life. Those little black dots were goats, dozens of goats! He walked me to the trailhead and pointed at the pale green tufts across the landscape. Mint, rosemary, sage, thyme, and verbena – these aromatic plants were right beneath my nose. This dusty landscape wasn’t so dead after all. He explained that the Amazigh people have extensive knowledge of the medicinal properties of hundreds of plants that grow in the High Atlas, and women will take several hour journeys to sell herbs in the valley markets. I wanted to learn more, but I was reminded of the long trek back to Tinerhir. I said goodbye, and thanked them all for such generous hospitality.

Afternoon tea with Amazigh family. Photography: Erin Jankovich
Morocco is dominated by a mountainous interior, bordered with rich coastal plains to the west and Sahara desert to the east. Since coming home from my trip, I have learned that this unique geography falls within the Mediterranean basin, a global biodiversity hotspot teeming with endemic flora and fauna found nowhere else on the planet (Rankou et al. 2013). Morocco alone has 879 endemic plants, the majority of which are restricted to the High Atlas region (Rankou et al., 2013).

The rich biodiversity of the High Atlas has been known to the Amazigh people for thousands of years, but only recently have researchers and scientists begun to draw their attention to this unique area. In 2015, scientists used IUCN Red List criteria to assess the status of endemic Moroccan flora and determined that many species are at risk of extinction due to climate change and habitat degradation (Rankou et al., 2015). These scientists emphasized that mountainous regions such as the High Atlas are especially sensitive to changes in climate and should be a top priority for conservationists, but so far very little research has gone into understanding the vegetation dynamics of this region.

Fresh and dry plants used for medicinal purposes found in traditional markets (image from Bouiamrine, 2017).
Many plant species picked by the Amazigh are highly toxic and dangerous to humans if not used appropriately (Mouhajir et al., 2001). Anecdotal evidence through surveys and interviews have revealed that the Amazigh people, specifically senior women, are experts in distinguishing between medicinal herbs and continue to pass on this traditional knowledge from one generation to the next (Bouiamrine, 2017). Many Moroccans still rely on traditional medicine to maintain good health thus conservation of these endemic herbs is critical for both the lives of the Amazigh and Moroccan market economy (Bouiamrine, 2017).

An Amazigh woman journeys across rugged terrain to sell herbs in modern markets. Photography: Erin Jankovich
I know better now that not all hotspots of biodiversity look like lush tropical jungles, but what they do have in common is an abundance of unique species that are threatened with extinction. Internationally the Mediterranean Basin has been recognized as providing significant ecosystem function and I was pleased to find that the Moroccan government has set national targets to preserve biodiversity and inventory traditional knowledge by 2020 (CBD, 2011).

Who better than the indigenous people of the High Atlas to help us understand the historical distribution of endemic plants and potential range shifts induced by climate change? Through sensitive and purposeful strategies for interaction with the Amazigh people—like the young student sharing a tea in the mountain—we may find that complimenting science with traditional ecological knowledge is the key to saving these unique landscapes.

Bouiamrine, E.H., Bachiri, L., Ibijbijen, J., & Nassiri, L. (2017). Use of medicinal plants in Middle Atlas of Morocco: potential health risks and indigenous knowledge in a Berber community. Journal of Medicinal Plant Studies, 5(2), 388-342.
Convention on Biological Diversity (2011). Electronic source. Retrieved from:
Mouhajir, F., Hudson, J.B., Rejdali, M., & Towers, G.H.N. (2001). Multiple antiviral of endemic medicinal plants used by Berber peoples of Morocco. Pharmaceutical Biology, 39(5), 364-374.
Rankou, H., Culham, A., Jury, S.L., & Christenhusz M.J.M. (2013). The endemic flora of Morocco. Phytotaxa, 78 (1), 1-69.
Rankou, H., Culham, A. ,Taleb, M.S., Ouhammou, A., Martin, G., & Jury, S.L. (2015). Conservation assessments and Red Listing of the endemic Moroccan flora (monocotyledons). Botanical Journal of the Linnean Society, 177, 507-575.

Friday, February 23, 2018

Moving on up to the regional scale

Like the blind men and the elephant, perspective drives understanding in ecology. The temporal and spatial scale of analysis (let alone the system and species you focus on) has major implications for your conclusions. Most ecologists recognize this fact, but consider only particular systems, scales or contexts due to practical limitations (funding, reasonable experimental time frames, studentship lengths). 

Ecologists have long known that regional processes affect local communities and that local processes affect regional patterns. Entire subfields like landscape ecology, metapopulations, metacommunities, and biogeography (species area relationships) highlight these spatial dependencies. But high-profile ecological research into biodiversity and ecosystem functioning ('BEF') primarily considers only local communities. Recently though, the literature has started to fill this gap and asking what BEF relationships look like at larger spatial scales, and how well local BEF relationships predict those at larger spatial scales.

'Traditional' BEF experiments were done at relatively small spatial scales (often only a few meters^2). Positive BEF relationships were commonly observed, but often were quite saturating – that is, only a few species were necessary to optimize the function of interest. If the impact of biodiversity saturates with only a few species, it would seem that surprisingly few species are necessary to maintain functioning. True, studies that considered multiple ecosystem functions are more likely to conclude that additional diversity is required for optimal functioning (e.g. Zavaleta et al. 2010). But a simplistic evaluation of the facts that a) ecosystem functioning rapidly saturates with diversity, and b) locally, diversity may not be generally decreasing (Vellend et al. 2017), could lead to overly confident conclusions about the dangers of biodiversity loss. Research on BEF relationships, as they transition from local to larger spatial scales, is increasingly suggesting that our understanding is incomplete, and that BEF relationships can grow stronger at large spatial scales.

A number of recent papers have explored this question, and in considering the essential role of spatial scale. Predictions about how BEF relationships will change with spatial scale vary. On one hand, in most systems there are only a few dominant species and these species may disproportionately contribute to ecosystem functions, regardless of the spatial scale. On the other hand, species-area relationships tend to increase rapidly at small scales, as community composition turns over. If that is the case, then different species may make important contributions in different places. Winifree et al. (2018) contrasted these predictions for three crop species that rely on natural bee pollinators (cranberries, blueberries, and watermelons). They censused pollinators at 48 sites, over a total extent of ~3700 km^2. Though at local scales very few bee species were required to reach pollination goals, the same goals at larger spatial scales required nearly an order of magnitude more bee species. These results in particular appeared to be driven by species turnover among sites--perhaps due to underlying environmental heterogeneity.
From Winifree et al. "Cumulative number of bee species required to maintain thresholds of 25% (orange), 50% (black), and 75% (purple) of the mean observed level of pollination, at each of n sites (16). Horizontal dashed lines indicate the total number of bee species observed in each study. Error bars represent 1 SD over all possible starting sites for expanding the spatial extent. For all three crops combined, each x-axis increment represents the addition of one site per crop".

Another mechanism for increased BEF at larger scales is insurance effects. The presence of greater diversity can interact with spatial and temporal environmental variation to increase or stabilize ecosystem functioning. Greater diversity should maximize the differential responses of species to changing conditions, and so buffer variation in ecosystem functioning. Such effects, when they occur through time are temporal insurance, and when they occur via dispersal among sites, spatial insurance. Wilcox et al. (2018) considered the role of synchrony and asynchrony among populations, communities, and metacommunities to ask whether local asynchrony affected stability (see Figure below for a nice conceptual explanation). Across hundreds of plant data sets, they found that asynchrony of populations did enhance stability. However, the degree to which it affected stability varied from very weak to very important (e.g. by 1% to 300%). Maximizing species or population differences at local scales apparently can have implications for dynamics, and so potentially stability of functioning, at much larger scales.

From Wilcox et al. "Conceptual figure showing how stability and synchrony at various spatial scales within a metacommunity combine to determine the stability of ecosystem function (here, productivity). In (a), high synchrony of species within and among local communities results in low stability at the scale of the metacommunity. In (b), species remain synchronised within local communities, but the two communities exhibit asynchronous dynamics due to low population synchrony among local patches. This results in relatively high gamma stability. Lastly, in (c), species exhibit asynchronous dynamics within local communities through time, and species-level dynamics are similar across communities (i.e. high population synchrony). This results in relatively high gamma stability. Blue boxes on the right outline stability components and mechanisms, and the hierarchical level at which they operate. Adapted from Mellin et al. (2014)."
Finally, Isbell et al. (2018) describe ways in which ecosystem functioning and other contributions of nature to humanity are scale-dependent, laying out the most useful paths for future work (see figure below).

From Isbell et al. 2018.
These papers make nearly identical points worth reiterating here: 1) we have done far too little work beyond the smallest spatial scales (~3 m^2) and so lack necessary knowledge of the impacts of losing of biodiversity, and 2) policy decisions and conservation activities are occurring at much larger scales – at the scale of the park, the state, or the nation. Bridging this gap is essential if we are to make any reasonable arguments as to why ecosystem function figure into  large-scale conservation activities.

Sustaining multiple ecosystem functions in grassland communities requires higher biodiversity. Erika S. Zavaleta, Jae R. Pasari, Kristin B. Hulvey, G. David Tilman. Proceedings of the National Academy of Sciences Jan 2010, 107 (4) 1443-1446; DOI: 10.1073/pnas.0906829107. 

Plant biodiversity change across scales during the Anthropocene. Vellend, Mark, et al. Annual review of plant biology 68 (2017): 563-586.

Species turnover promotes the importance of bee diversity for crop pollination at regional scales. RACHAEL WINFREE, JAMES R. REILLY, IGNASI BARTOMEUS, DANIEL P. CARIVEAU, NEAL M. WILLIAMS, JASON GIBBS. SCIENCE16 FEB 2018 : 791-793

Asynchrony among local communities stabilises ecosystem function of metacommunities. Kevin R. Wilcox, et al. Ecology Letters. Volume 20, Issue 12, Pages 1534–1545.

Isbell, Forest, et al. "Linking the influence and dependence of people on biodiversity across scales." Nature 546.7656 (2017): 65.