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From Lynx to Coyotes: How Climate Change Has Impacted Hare Predation

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Climate change increases predation risk for a keystone species of the boreal forest

By: Michael J.L. Peers, Yasmine N. Majchrzak, Allyson K. Menzies, Emily K. Studd, Guillaume Bastille-Rousseau, Rudy Boonstra, Murray Humphries, Thomas S. Jung, Alice J. Kenney, Charles J. Krebs, Dennis L. Murray, and Stan Boutin

Summarized by: Anna Geldert

What data were used? Researchers observed 321 snowshoe hares in southwestern Yukon from 2015-2018. Researchers also monitored changes in weather and snow conditions within the study region, including temperature, snow depth, snow hardness and daily snowfall.

Methods: Hares were captured in live traps and given collars with mortality sensors before being released back into the wild. In the event of hare death, researchers visited the site to identify any predators responsible for the death by looking for tracks, scat, and other indicators in the surrounding area. Researchers recorded data on weather and snow conditions at three different sites throughout the study region on a nearly daily basis, as well as at each kill site. They then used a computer model to compare the likelihood of hare death under different weather conditions (e.g., temperature, snow depth, and snow hardness), and generated a best fit line to model these relationships. Similar models compared weather conditions to hare predation from lynx and coyote, hare death by age group, and hare foraging time by age group. The models were tested by inputting randomized data and estimating uncertainty.

Results: Researchers found that 153 hares died of predation. Lynx and coyote were the most common predators, accounting for 59.4% and 25.5% of deaths respectively. Hare survival was lowest in 2015-2016, countering the predicted increase in hare populations based on predator-prey cycles. Low survival rates were correlated with shallow snow depth and high snow hardness. . The relationships between hare survival and these weather conditions are most likely due to changes in predator threats, not changes in foraging behavior. While lynx predation remained relatively constant across a wide range of snow conditions, coyote predation increased by a factor of 1.155 with higher snow depth and 1.244 with lower snow hardness.

The figure graphs the relationship between snow depth and hare predation risk by lynx and coyotes. The x-axis is labeled “snow depth (cm),” and ranges from 20 to 70, increasing at intervals of 10. The y-axis is labeled “risk (relative to baseline),” and ranges from 0 to 15, increasing at intervals of 5. A legend indicates that the purple line represents risk from lynx while the red line represents risk from coyotes. At a risk measurement of 1, a dotted line runs horizontally (slope=0) across the graph; this represents baseline risk. The risk from lynx almost exactly coincides with the baseline risk, indicating that snow depth has little impact. On the other hand, the risk for coyote has an inverse relationship with snow depth. At a snow depth of 20 centimeters (the lowest depth represented), risk from coyotes is approximately 10. The risk line then decreases exponentially, crossing the baseline risk at approximately 35 centimeters and plateauing close to a risk of zero around 50 centimeters.
Fig. 1. Hare predation risk by lynx and coyotes at different snow depths. The dotted line represents a baseline risk, while shaded regions represent standard errors.

Why is this study important? This study is an important example of the cascading effects that climate change can have on ecosystems in the boreal forest. Increasing temperatures due to climate change have altered traditional snow conditions in the Yukon, leading to lower snow depth and snow hardness in recent years. Coyotes – who, unlike lynx, are not well adapted to harsh winters – have gained a relative advantage in these milder conditions, leading to increased hare predation. Risk has increased so much, in fact, that they disrupted the natural rise and fall of hare populations due to existing predator-prey cycles. If these trends continue, they could potentially impact other aspects of boreal forest ecosystems.

The big picture: It is widely recognized that climate change threatens the survival of many species and ecosystems around the globe. However, this is most often talked about in terms of direct threats, such as increasing temperature, increasing severe weather conditions, etc. This article demonstrates that a further concern, particularly in boreal forests, is the impact of changing climatic conditions on food webs and predation threats. Further research is needed to determine if the changing predator-prey relationships between hares and coyotes in this study are consistent in other regions of boreal forest, and whether similar trends are reflected in other biomes as well.

Citation: Peers, M. J. L., Majchrzak, Y. N., Menzies, A. K., Studd, E. K., Bastille-Rousseau, G., Boonstra, R., … Boutin, S. (2020). Climate change increases predation risk for a keystone species of the boreal forest. Nature Climate Change, 10(12), 1149–1153. https://doi.org/10.1038/s41558-020-00908-4

How climate change is affecting Pacific species

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Assessing the vulnerability of marine life to climate change in the Pacific Islands region

Giddens J, Kobayashi DR, Mukai GNM, Asher J, Birkeland C, Fitchett M, et al.

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? The researchers assessed 83 species grouped into six functional groups based on range size and habitat: pelagic, shark, deep-slope, coastal, coral reef, and invertebrate species. The “coral reef” group of fishes contained many species, so it was further divided into JEGS (Jacks, Emperors, Groupers, Snappers), parrotfishes, surgeon fishes, and “other coral reef” fishes. The species were chosen based on expert opinion, importance of their ecosystem function, records of food fish, and cultural and conservation importance. The species came from a wide range of locations in the Central, West, and South Pacific Ocean. 

To determine the climate change vulnerability of the species, the researchers considered two components: exposure and sensitivity. Exposure was defined as to what degree an organism is likely to experience a negative change in a particular physical variable. Sensitivity was considered a biological trait-based variable, which the researchers determined by review of existing literature and expert opinion. 

Methods: To assess exposure, data from various sources was compiled based on certain variables that were the most significant for species living in the Pacific Islands Region: temperature (surface and bottom), salinity (surface and bottom), ocean acidification (pH), mixed layer depth, precipitation, current velocity, wind stress, surface oxygen, sea level rise, wave height, chlorophyll, and primary productivity. To determine sensitivity, experts were asked to identify the six most important sensitivity attributes for each species out of 12: habitat specificity; prey specificity, complexity in reproductive strategy, sensitivity to ocean acidification, early life history survival and settlement requirements, dispersal of early life stages, sensitivity to temperature, population growth rate, stock size/status, adult mobility, spawning cycle, and other stressors (including habitat degradation, pollution, disease, or changes in the food web). 

For each species, a component score was calculated for both exposure and sensitivity based on the number of factors/attributes that passed a certain threshold. Then, the overall climate change vulnerability rank was calculated by multiplying the exposure and sensitivity component scores. The numerical values for the climate vulnerability rank were the following: 1–3 (low), 4–6 (moderate), 8–9 (high), and 12–16 (very high).

Grid where each square shows what percentage of a species is considered “moderate”, “high”, or “very high” in vulnerability. The squares are shown in greyscale, with 0% being white and 100% being black. Approximate values: Pelagic: 90% moderate, 10% high Shark: 10% moderate, 30% high, 60% very high Deep slope: 60% moderate, 40% high Coastal: 100% moderate Coral reef JEGS: 80% moderate, 20% high Coral reef parrotfish: 60% moderate, 30% high, 10% very high Coral reef surgeonfish: 25% moderate, 75% high “Other” coral reef: 65% moderate, 25% high, 10% very high Invertebrate: 10% moderate, 30% high, 60% very high
The percentage of species within the group that fell within each vulnerability ranking.

Results: All species ranked “very high” in the overall exposure component of vulnerability. It was determined that this was caused by three influences: decrease in oxygen concentration, rise in sea surface temperature, and increase in ocean acidification (decrease in surface pH). In the sensitivity component, it was found that the groups that were made up of larger-bodied species shared similar sensitivity scores, while the groups with smaller and site-attached species tended to differ.

In the overall assessment of climate change vulnerability, the species showed a wide range in vulnerability across the functional groups. The larger and more wide-ranging pelagic and coastal species were scored as the least vulnerable, while the smaller and more site-attached species (small coral reef fishes and invertebrates) were the most vulnerable. Some groups had a more general ranking across all the included species (for example in the coastal group all the species were ranked as “moderate”), while in others there was a wider distribution across vulnerability rankings. 

Why is this study important? Most studies on the effect of climate change of ocean ecosystems focus on a particular or particular type of species, or on singular factors. This study assessed many factors affecting many species, which creates a more all-encompassing view of the effects of climate change and enables focus on the ecosystem as a whole rather than looking at it in pieces. 

The big picture: Well-functioning ocean ecosystems are essential to the health of the planet, but there is still a lack of both information about the ecosystems and the organization and usage of that information. Collecting data on marine species and the environmental factors that affect them (and to what degree) is necessary to their preservation.

Citation: Giddens J, Kobayashi DR, Mukai GNM, Asher J, Birkeland C, Fitchett M, et al. (2022) Assessing the vulnerability of marine life to climate change in the Pacific Islands region. PLoS ONE 17(7): e0270930. https://doi.org/10.1371/journal.pone.0270930

Horseshoe Crabs Teach Us About Heterochrony

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A new method for quantifying heterochrony in evolutionary lineages

James C. Lamsdell

Summarized by Anna Geldert

What data were used? A total of 20 traits that display heterochronic conditions for 54 species of horseshoe crabs (both living and extinct) were studied. 256 traits were examined and documented in these horseshoe crabs and 99 related species to make a character matrix. Of the 54 horseshoe crabs, environmental data from previous studies was also collected to determine the species’ habitat..

Methods: This paper presents a new method for quantifying heterochrony through a process called “heterochronic weighting.” Heterochrony is a process that alters the timing and length of developmental stages of organisms, and is characterized as either paedomorphism (retaining juvenile characteristics as an adult) or peramorphism (developing beyond what is seen in related species; more “adult-like”.) For each characteristic, paedomorphic traits were assigned a score of -1, peramorphic traits were assigned a score of +1, and neutral characteristics were assigned a score of 0. The heterochronic weighting of a species was then defined as the sum of all scores divided by the number of characteristics. The author also looked at heterochrony in an evolutionary context. He generated a probable evolutionary tree using a computer model that related species based on shared traits. He then used the tree to determine the heterochronic weighting of the clade (i.e., evolutionary group) by averaging those of the individual species. The differences in heterochronic wightings between habitat preferences (marine or nonmarine) and clades were tested for statistical significance. Lastly, the author tested to see if there were concerted trends towards paedomorphy or peramorphy in each clade.  The evolutionary tree was also tested to determine the most likely habitat for ancestry species of horseshoe crabs, which gave insight to when shifts from marine to nonmarine environments occurred.

The figure shows a diagram of the heterochronic conditions as seen in limb length. Three drawings of the underside of the head shield of a horseshoe crabs are shown side by side. There is one small pair of claw-like appendages towards the front of the head shield and ten longer walking limbs visible. The first diagram has the longest limbs, extending outside the shell. It is labeled “-1,” representing a paedomorphic condition. The second diagram, labeled “0” for a neutral condition, has shorter limbs that are all contained under the shell, though some extend nearly to the edge. Lastly, the final diagram is labeled “+1” for a peramorphic condition. The limbs of the crab in this diagram are the shortest, spanning only a third to a half the width of the shell.
Fig 1. Variations in limb length serve as an example of a heterochronic characteristic in horseshoe crabs. Paedomorphic (-1), neutral (0), and peramorphic (+1) conditions are shown.

Results: Overall, heterochronic weighting proved successful in quantifying the paedomorphic and peramorphic changes in horseshoe crab characteristics. Of the four clades studied, two (Bellinurina and Austrolimulidae) were found to have statistically significant occurrences of heterochrony, with Bellinurina trending towards paedomorphic characteristics and Austrolimulidae trending towards peramorphic characteristics. The Paleolimulidae clade was characterized as having non-significant  heterochronic weightings, while the Limulidae showed a slight peramorphic trend that could be explained by random evolution, not necessarily a concerted trend. More extreme heterochronic weightings (both positive and negative) were associated with the evolutionary transition to non-marine habitats, as was the case for both Bellinurina and Austrolimulidae clades.

Why is this study important? First and foremost, this study is important because it developed a method for quantifying instances of heterochrony, which has not been studied in a combined phylogenetic and ecological context. This gives insight into the interaction between ecology and heterochrony, especially as an evolutionary mechanism. For example, it is noteworthy that both clades that transitioned to non-ancestral nonmarine environments (Bellinurina and Austrolimulidae) experienced higher rates of heterochrony, suggesting that greater ecological change may correlate with increased likelihood for developmental changes in horseshoe crabs. However, it is also important to recognize that environmental affinity is not the only factor influencing heterochrony, or else Bellinurina and Austrolimulidae would have developed in the same way, trending towards either paedomorphic or peramorphic characteristics. The opposite trajectories of the two clades suggests that environmental pressures may increase heterochrony, but underlying genetic factors determine the direction of development.

The big picture: The process of heterochronic weighting developed in this study has the potential to advance the field of paleobiology, as the author was now able to quantify paedomorphy and peramorphy throughout evolutionary history. This allows for a deeper understanding of the relationship between an evolutionary mechanism and other factors, such as ecological affinity or evolutionary relatedness. However, as this study is so far the only study to have employed heterochronic weighting so far, the success rate of this process is limited to horseshoe crabs. Therefore, further research is needed to determine the effectiveness of this method for heterochrony in other species groups.

Citation: Lamsdell, J. C. (2020). A new method for quantifying heterochrony in evolutionary lineages. Paleobiology, 47(2), 363–384. https://doi.org/10.1017/pab.2020.17

How Ancient Ocean Chemistry Might Have Increased Complexity of Life

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Ediacaran Reorganization of the Marine Phosphorus Cycle 

Thomas A. Laaksoa, Erik A. Sperling, David T. Johnstona, and Andrew H. Knoll

Summarized by Makayla Palm

What data were used? The purpose of this study was to measure if changes in the phosphorus cycle were linked to changes in the chemical composition of ocean water hundreds of millions of years ago. The phosphorus cycle is the study of the element phosphorus as it travels from deep-sea storage and rock formations into organic life, and back to the seas again. Why study phosphorus in the first place? Phosphorus is essential to life because it is an important component in DNA and RNA structure. Specifically, at the end of the Ediacaran (~625–542 million years ago or mya), there was a jump in complexity in the fossil record (i.e., life became more complex) found in the transition from the Ediacaran to the Cambrian (~542–485 mya); it may be the case that this change in phosphorus can help us understand the changes to life on Earth during this time. Previously collected phosphorite samples (rocks with a high phosphorus content) and newly found samples from the Doushantuo Formation (Ediacaran, China) were used in this study. These phosphorite samples were examined for the following: evaporite volume, strontium isotope ratios, and content of phosphate. Changes in these samples’ ratios and concentrations allow researchers to hypothesize the impacts on water and life during the Ediacaran. Originally, scientists thought the changes may have been due to increased weathering of rocks, but researchers in this study hypothesized that there may have been more to the story. 

Methods: Researchers from this study hypothesized that a change within deeper Ediacaran ocean chemistry may be the cause for the phosphorus cycle change. They tested this hypothesis by using the variables collected (e.g., isotopes) in an equation that measures the possible effects of the phosphorus evaporite remineralizing into phosphorite (typically how phosphorus is stored in the ocean) This equation measures the amount of phosphorus taken out of the storage bank by measuring the fraction of total organic phosphorus that is removed in relation to the amount of phosphorus that reverts back to its original form in the storage bank. 

Results: The changes in ocean chemistry can be found on the atomic scale, where there are electron acceptors (also known as oxidizers) and electron donors (or reducers). The ocean, having been in a state of consistent reducing reactions, may have shifted to have more oxidizers, which would have increased remineralization – specifically, phosphorus remineralization. This remineralization would explain the difference that eventually modified the Ediacaran phosphorus cycle to the modern-day phosphorus cycle. In order for phosphorus to reduce, something needs to accept its electron. In the absence of oxygen (which early Earth was lacking in for billions of years), research indicates sulfate may be a suitable candidate. Samples of sediment did not indicate a change in phosphorus content, so the hypothesis was not supported. This means that the phosphorus was likely staying within the same system and being removed. The phosphorus cycle, similar to the water cycle or carbon cycle, describes the formation, use and recycling of phosphorus from the oceans, to land, and back to the ocean. The data from this study indicate that upwelling, the mixing of nutrients from the bottom of the ocean back to the top, is the reason for increased phosphorus. Upwelling can be caused by deep water currents coming into contact with continents, where cold, nutrient rich water is propelled closer to the surface and warms. The increased upwelling makes sense in the phosphorus cycle because of the extra circulation happening, which would explain the increased presence of phosphorus without an added source of the element. 

This figure represents three different kinds of information collected over the same period of time. The top graph is a bar graph that measures the amount of phosphate evaporite that was removed and not returned to the phosphorus storage bank. The middle bar graph measures the total amount of phosphate resources stored in the form of P2O5. This graph represents the amount in millions of tons. The line graph at the bottom of the figure represents the number of strontium isotopes found within the rock samples. This graph represents inconsistent intervals of small increasing and decreasing values, showing an overall increase through time in each graph. Across all three graphs, columns highlight the appearance of phytoplankton and large animals within the fossil record. The appearance of phytoplankton is approximately 700 million years ago, and the appearance of larger animals is around 720-699 million years ago. The appearance of both is marked by horizontal black bars at the bottom; with each appearance, there is an uptick in strontium 87. More complex life is marked by more phosphate and evaporites. These bars represent the appearance of organisms in all three line graphs.
The figure represents the three different kinds of data discussed in the paper. The top demonstrates the volume ( km cubed) of phosphorite evaporite, with a general trend of increasing evaporite over time.The middle graph represents the amount of phosphate resources stored in the “storage bank” in the ocean (in millions of tons). The bottom graph represents the change in Strontium isotopes, with ebb and flow in value over time, with a general trend that after a strong dip ~ 700 million years, trends upward. Ice ages are indicated with gray vertical bars across all three graphs, indicating a change in ecosystem. The dark horizontal bars at the bottom of the figure indicate when the appearance of phytoplankton and macroscopic animals occur, which is ~ 680 million years for the phytoplankton and ~ 650 million years for the macroscopic animals. The vertical gray shading represents Ice Ages that occurred in the timeline measured on the figure. The figure as a whole points to the correlation of increased phosphorite levels and the first appearance of relatively large animals in the fossil record.

Why is this study important? This study aims to see why the change in phosphorus occurred to better understand the geologic context that precedes a big change in the fossil record. There is a large jump in complexity from Ediacaran to Cambrian organisms, and ocean chemistry (changes in phosphorus levels in this case) may have had something to do with that. The cycling of phosphorus because of upwelling, influenced by continental placement, could have been a driving reason behind these big changes, ecological and evolutionary. 

Big Picture. This study proposes a mechanism for the change in the phosphorus cycle that is observed between the phosphorus cycle today and the phosphorus cycle of the Ediacaran as we know it. Many questions still exist as to how oceans have changed through geologic time and this study provides an important piece to the puzzle. Understanding changes in ocean chemistry, too, better helps scientists understand how life evolves in response. 

Citation: Laakso, Thomas A., et al. “Ediacaran Reorganization of the Marine Phosphorus Cycle.” Proceedings of the National Academy of Sciences, vol. 117, no. 22, 2020, pp. 11961–11967., https://doi.org/10.1073/pnas.1916738117. 

Early childhood and connecting with nature

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Effect of environmental education on the knowledge of aquatic ecosystems and reconnection with nature in early childhood

Maria João Feio, Ana Isabel Mantas, Sónia R. Q. Serra, Ana Raquel Calapez, Salomé F. P. Almeida, Manuela C. Sales, Mário Montenegro, Francisca Moreira

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? In 2018, the environmental educational project CresceRio was created in the city of Coimbra, Portugal, to encourage the populace to reconnect with nature, preserve and protect the streams found in the area, and teach children about the importance of the streams and preserving green and blue (terrestrial and aquatic) ecosystems. Most children who live in the city had little exposure to nature and expressed fear and incorrect knowledge about the streams and rivers in their area. It was proposed that introducing field trips to natural areas and hands-on activities to school curriculums would be a low cost yet effective way to improve their relationship with the natural world. 

Methods: Over the course of 14 months, the researchers conducted several surveys with a class of 24 students (aged 5–6 at the beginning of the program). At particular intervals (labeled M), the children were questioned about five main topics: their identification and background, their awareness of streams and rivers, their recognition of the biodiversity that existed in the rivers, their awareness of various factors negatively affecting the rivers, and their awareness of the ecosystem services provided by rivers to the population. 

M1 occurred at the beginning of the program (September 2018) and was followed the next month by a trip to a stream outside of the city that was not seriously affected by urban activity. M2 occurred in November 2018, and the students visited an urban stream that was visibly affected by urban activity including construction, removal of trees, and litter. In February 2019, the students participated in a laboratory class where they examined fallen leaves and were taught to identify various invertebrates and algae using microscopes. M3 took place in March 2019, followed by a workshop in June 2019 where they reviewed photos and videos and discussed what they learned from their previous activities. In October 2019 they visited another urban stream that was slightly less altered than the one they visited before. The last survey was conducted in November 2019 and was done in the form of group interviews. 

Results: The three main takeaways that the researchers identified were 1) that children in urban areas have little contact with or knowledge of nature, 2) after a year of exploring the streams and their ecosystems their knowledge increased (both about the ecosystems and the problems they face) and their fears decreased, and 3) the long duration of the program was key as changes in their attitude and knowledge only became clear after a few activities.

In all five categories explored (personal background and experience, awareness of aquatic ecosystems, recognition of biodiversity, awareness of issues affecting rivers, and awareness of services provided by rivers) the students showed increased interest and cognizance of the streams by the end of the program. Students were more aware of the streams close to where they live as well as the animals (other than fish) that lived there, such as birds and insects. The activities and field trips lessened their fears of imaginary creatures or animals like alligators that did not exist in Portuguese rivers and made them more appreciative of the streams as a resource for water and recreation. They also acknowledged the presence of trees on the banks of the streams that provided oxygen, shelter, and food for animals. The children also showed an increased negativity for litter, lack of trees, too many reeds (that grow unchecked when trees are removed and choke the stream) and too many buildings around the streams. The students were also reported as saying that they would not litter and would discourage others from doing so as well.

The bar graph shows 3 bars for each organism, showing the percentage of students that recognize that organism at the time of the M1, M2, and M3 surveys. Approximate values are: Fauna Fish: M1- 60%, M2- 92%, M3- 87% Invertebrates: M1- 30%, M2- 40%, M3- 75% Insects: M1- 42%, M2- 44%, M3- 33% Dragonflies: M1- 39%, M2- 50%, M3- 68% Butterflies: M1- 30%, M2- 25%, M3- 22% Mosquitoes: M1- 48%, M2- 45%, M3- 38% Shrimps: M1- 60%, M2- 47%, M3- 53% Aquatic snails: M1- 25%, M2- 59%, M3- 30% Mammals: M1- 21%, M2- 19%, M3- 38% Amphibians: M1- 12%, M2- 22%, M3- 25% Birds: M1- 27%, M2- 37%, M3- 30% Aquatic flora Algae: M1- 60%, M2- 82%, M3- 97% Filamentous green algae: M1- 39%, M2- 45%, M3- 79% Aquatic plants: M1- 39%, M2- 63%, M3- 70% Trees Alders: M1- 23%, M2- 18%, M3- 38% Willows: M1- 17%, M2- 27%, M3- 62% Poplars: M1- 10%, M2- 40%, M3-70 % Oaks: M1- 21%, M2- 50%, M3- 70% Ash trees: M1- 17%, M2- 18%, M3- 37%
Figure 1: The percentage of students that can recognize particular flora or fauna over time and as they are more exposed to streams and the organisms that live there.

Why is this study important? Children growing up in urban areas are exposed to various pollutants and obstacles that come from living in the city. Being consistently exposed to nature from an early age can help to combat those negative effects and promote health and wellbeing. Additionally, learning about the importance of aquatic ecosystems naturally inspires children to be interested in conservation and sustainability. This study showed that when given the opportunity to have real experiences in nature, they form their own positive opinions and ideas.

The big picture: Conservation of green and blue ecosystems is dependent on future generations having genuine understanding of and connections to nature. Introducing environmental studies, complete with hands-on activities, to primary education curriculums is an effective way to nurture those connections. Children should be exposed to the natural spaces close to their schools and homes in order to feel connected to nature and have a deeper learning experience.

In the “before” images (a) and (b), the children drew pictures where only a small portion depicts the stream. A few fish are shown, but most of the detail shows the dock, land, buildings and trees, a large portion of sky, and in image (b) lots of people. In the “after” images (c) and (d), the children’s pictures show a large amount of water and a lot of biodiversity, with pictures of insects, snails, and birds.
Figure 2: Pictures drawn by students after their first field trip (a and b) and after their second field trip and laboratory class (c and d)

Citation: Feio MJ, Mantas AI, Serra SRQ, Calapez AR, Almeida SFP, et al. (2022) Effect of environmental education on the knowledge of aquatic ecosystems and reconnection with nature in early childhood. PLOS ONE 17(4): e0266776. https://doi.org/10.1371/journal.pone.0266776

Trees Combat Climate Change in China by Reducing CO2 Levels

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Forest management in southern China generates short term extensive carbon sequestration

By: Xiaowei Tong, Martin Brandt, Yuemin Yue, Philippe Ciais, Martin Rudbeck Jepsen, Josep Penuelas, Jean-Pierre Wigneron, Xiangming Xiao, Xiao-Peng Song, Stephanie Horion, Kjeld Rasmussen, Sassan Saatchi, Lei Fan, Kelin Wang, Bing Zhang, Zhengchao Chen, Yuhang Wang, Xiaojun Li and Rasmus Fensholt

Summarized by Anna Geldert

What data were used? Researchers collected data on carbon storage (long-term carbon stocks) and sequestration levels (new uptake of carbon gasses) by forest type. Data was recorded between 2002 and 2017, and the area of study focused on eight provinces in southern China. This data was compared with existing published data on soil moisture levels and national CO2 emissions.

Methods: Researchers used satellite imagery data from MODIS (Moderate Resolution Imaging Spectroradiometer) for the basis of this study. Using approximately 10,000 MODIS images, they divided the area into a grid with a scale of 0.25km2. Using “training points” of known land cover, they trained a computer to estimate the probability of forest cover in each grid cell, as well as the level of change in forest cover over time. Based on this information, grid cells were classified into eight categories of forest types, including dense forest (probability of forest cover ≥ 0.8, with low change), persistent forest (probability ≥ 0.5, with low change), persistent non-forest (probability ≤ 0.5, with low change), recovery (regrowth of deforested areas, causing a gradual shift from non-forest to forest), afforestation (tree plantation in previously unforested areas, causing a rapid shift from non-forest to forests), deforestation (shift from forest to non-forest), rotation (harvested area, causing fluctuation between forest and non-forest) and rotationL (harvested area, causing fluctuations and low forest recovery). Researchers then estimated the carbon density of each forest type using data from a previous study 2015 from GLAS (Geoscience Laser Altimeter System, i.e., a satellite machine designed to measure the vertical structure of forests). MODIS data from this study was cross-referenced with existing passive microwave data from SMOS (soil moisture and ocean salinity), which also measured carbon density from this region, though on a broader scale. SMOS data were also used to determine the average soil moisture in the studied region.

Results: Both tree cover and fossil fuel emissions increased considerably between 2002 and 2017. Using the MODIS data, researchers estimates a carbon sink of 0.11 Pg C year-1 (i.e., petagrams of carbon per year, the equivalent of 0.11 billion metric tons per year) in the region studied. This accounted for roughly 33% of yearly carbon emissions since the year 2012. Unmanaged dense forest had the highest carbon density, accounting for 20.5% of carbon storage despite only occupying 8.8% of the land. However, dense forests had low levels of carbon sequestration, accounting for only 4% of the total uptake. Comparatively, persistent non-forests and managed forests (recovering, afforestation, and rotation areas) all had low levels of carbon storage but accounted for 65% the total carbon sequestration. Persistent forest areas lay somewhere in the middle, with moderate storage and sequestration levels. Heavily harvested forests (deforested and rotationL areas) had much lower sequestration rates, and served as carbon sources rather than sinks. Finally, SMOS data revealed that soil moisture levels tended to be lower in regions with lots of managed forests.

The figure shows a bar graph comparing the type of land to the level of sequestration of CO2 emissions. The x-axis is labeled “Type of land use,” and is numbered 1 through 8. A legend on the right of the graph indicates that each number corresponds to a type of forest or non-forest area: 1 represents dense forest, 2 represents forest, 3 is non-forest, 4 is recovery, 5 is afforestation, 6 is deforestation, 7 is rotation, and 8 in rotationL. A different y-axis is present on either side of the graph, so that both the relative percent of CO2 emissions sequestered and the numerical quantity of carbon sequestered per year are represented. The left axis represents the percentages, and spans from 0 to 7.5, increasing at increments of 1.25. The right axis represents the quantity of carbon sequestered in petagrams per year, spanning from 0.00 to 0.03 and increasing by a factor of 0.05. A separate legend on the bottom of the graph indicates that the dark orange portions of the bars represent the percentage/fraction of carbon sequestered compared to CO2 emissions from China as a whole, while light orange portions correspond to emissions from the eight provinces alone. The land use type with the highest percentage of carbon sequestered was non-forest, which accounted for approximately 6.5% of annual emissions for the eight provinces, or 0.026 total Pg of carbon per year. Non-forest was followed by forest and afforestation (both accounting for 5.2% of emissions and 0.21 total Pg), recovery (4% and 0.016 Pg), rotation (3.5% and 0.013 Pg) and dense forest (1% and 0.009 Pg). Deforestation and rotationL were the only types of land use to represent a negative percentage and quantity of carbon sequestered, indicating that they served as a carbon source rather than a carbon sink. Deforestation accounted for approximately -0.2% (or 0.001 Pg) of carbon sequestration, while rotationL was nearly negligible. The percentages of carbon sequestered when compared to national emissions (dark orange) were all about one fifth of the percentages when compared to the eight provinces alone.
Fig. 1. Average percent of CO2 emissions sequestered annually by each forest type. CO2 emissions from the eight provinces in the study region, as well as emissions from China as a whole, are both shown.

Why is this study important? This study compares the effectiveness of different types of forests in mitigating the impacts of climate change. While natural, dense forests were the best at storing carbon long-term, managed forests were most effective at rapidly removing CO2 from the atmosphere on a shorter timescale. Harvested forests, especially those classified as “rotation,” were especially successful as they were able to sequester relatively high levels of carbon while still providing significant economic revenue from timber for the region. Overall, changes in forest management policies in China in 2002 led to an impressive reduction in carbon emission levels (33%). However, it is important to note that an additional 3 million km2 of forested land would be needed to reach net zero carbon emissions, a number which is unreachable in this region. Likewise, reduced levels of soil moisture indicate that heavily managed forests may not be sustainable in the long run, and will likely be less effective during periods of drought. More research is needed to determine if these forest management policies have already reached maximum effectiveness, or if other adjustments can be made to further increase sequestration.

The big picture: As the main drivers of climate change, fossil fuel emissions continue to threaten our planet. Forestation and forest management policies, such as those established in China at the turn of the century, are a way to mitigate the impact of greenhouse gasses. Modeling future policies after these could help increase carbon sequestration worldwide, especially until renewable energy becomes available. However, as was revealed in this study, it is nearly impossible at current emission levels to reach net zero carbon emissions through forest management alone; in the long term, forest management will likely need to be combined with other policies to ensure a sustainable future.

Citation: Tong, X., Brandt, M., Yue, Y., Ciais, P., Rudbeck Jepsen, M., Penuelas, J., … Fensholt, R. (2020). Forest management in southern China generates short term extensive carbon sequestration. Nature Communications, 11(1). https://doi.org/10.1038/s41467-019-13798-8

Synchronized Shedders? Trilobites Molting Patterns and Implications on Defense Strategy

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Synchronized Moulting Behavior in Trilobites from the Cambrian Series 2 of South China

Alejandro Corrales-García, Jorge Esteve, Yuanlong Zhao,  and Xinglian Yang

Summarized by Makayla Palm

What data were used? Slabs of trilobites found from Cambrian-age rocks in South China were discovered in large clusters of several hundred individuals. There were several species represented within these clusters. Were these full trilobites? These fossils did not have a cephalon, or a protective head “shield” that concealed sensory organs, indicating they were molts, or leftover exoskeletons that had been shed off after a molting cycle (much like modern lobsters and tarantulas, which belong to the same phylum as trilobites, Arthropoda). All of the trilobite specimens were measured; scientists planned to use this data to test the hypothesis that these specific taxa, or groups of trilobites, had the same molting patterns as other members of Arthropoda. 

Methods: Scientists recorded measurement data to estimate average specimen size for each species. Researchers performed other data analyses, as well, such as: if different species were clustered together (or not), the orientation of the trilobites, or the way they were facing (e.g., – dorsal, or back, up or down) to learn more about how they were buried, and how differently the exoskeletons had molted, by observing how they deviated from a typical, complete trilobite.

Results: The sizes for all the species were all relatively small, which is evidence to support the idea they had gathered to molt for protection. If they had clustered together for reproduction, various sizes would have been found together. The smaller sizes indicate these may have been juveniles that stuck together for strength in numbers, which is observed in modern-day arthropods. The researchers observed all of the previous molting patterns found in other trilobites in these four trilobite species, confirming a wide variety of species molted in similar ways. They also observed that each species was clustered together and they had not intermixed with one another. The fact that these species did not intermix implies group synchronization, which is found in extant species of arthropods as a defense mechanism. It is inferred that these trilobites coordinated their molts in order to protect themselves during the vulnerable process of molting, which leaves their softer insides more exposed to predation until their new exoskeleton hardens.

There are ten known ways of trilobite molting, with various parts of the body either missing or displaced, depending on the growth stage the trilobite was in or if the trilobite needed to replace any body parts.There are two rows of five configurations. All of these configurations are with a dorsal view. The first five configurations are where different parts of the body are omitted, but not disfigured or displaced. Configuration A is missing the top of the head that extends around and almost touches the side. Configuration B is missing the inner part of the head and retains the outer rim of the head. Configuration C is missing the segment that connects the head with the thorax. Configurations D and E are missing body segments in the thorax. Configuration F has the crown of the head displaced under the thorax. Configuration G is missing the crown of the head and the connection between the head and thorax. Configuration H has all parts, but they are disconnected. Configuration I has the head bent forward on top of the thorax. Configuration J has the crown facing down and behind the thorax.
There are ten different molting configurations found within the cluster of trilobites found in all species of the study. The molting patterns differ in where a segment of the exoskeleton is missing, a body part displaced, or a body part that has been shifted. For example, some of the head pieces have been removed or displaced to lay behind the rest of the body. There are pieces of the thorax missing in some, or shifted relative to the rest of the body. These different configurations represent the known molting patterns of trilobites and show clear similarities in molting patterns with extant arthropod species. The relatively small size of the trilobites indicates they may have banded together for protection against predators, and molted in groups for strength in numbers.

Why is this study important? Several different trilobite types in Cambrian strata were found clustered together, but the fossilized remains weren’t complete trilobites. These were molts or leftover exoskeletons they had outgrown and shed. Molting is a common behavior in living arthropods today, and there are certain ways these creatures can molt. Several of these molting patterns have been described and documented previous to this study in other trilobites, and this study expanded on knowledge of molting patterns. This study also shows evidence that trilobites may have worked together in synchronized molting as a protection mechanism.  

The big picture: Fossils like these preserved here, along with modern analogs, can help us understand more about the behavior of long-extinct organisms.  Evidence from extant species of arthropods today has shown groups of species molt together as a defense mechanism, and the hypothesis of this paper was that the four tested groups of trilobites did the same thing. By finding the different species separated in different groups with various molting patterns, the researchers were able to conclude these trilobites likely synchronized, or coordinated molting together in groups. 

Citation: Corrales-García, A., Esteve, J., Zhao, Y., & Yang, X. (2020). Synchronized moulting behaviour in trilobites from the Cambrian Series 2 of South China. Scientific reports, 10(1), 1-11.

Wetlands and Wildlife

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The relationship between biodiversity and wetland cover varies across regions of the conterminous United States

Jeremy S. Dertien, Stella Self, Beth E. Ross, Kyle Barrett, and Robert F. Baldwin

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? Using data from the National Wetlands Inventory and the National Land Cover Database, the researchers modeled wetland cover for the conterminous (continental 48) United States and collected estimates for how much wetland existed in the continental U.S. in 2001 and 2011. From various other sources they compiled more information essential to understanding wetland habitats: which animal species live in the areas and their distribution/ranges, the average temperatures and precipitation levels of the wetlands, and the elevation or altitude. 

Methods: The maps showing the ranges of the endemic (native) birds, mammals, reptiles, and amphibians were accumulated into one endemics raster (a grid where each cell represents a piece of data) for analysis. Each cell represented a 10×10 km area, so the estimated amount of wetland cover (in hectares) per every 100 km² was the focus. Wetlands smaller than 0.01 hectares and large bodies of water were removed from the data to prevent flawed or biased results. 

To calculate wetland change, the researchers subtracted the wetland cover estimates of 2011 from the 2001 coverage to calculate the 10-year change. To calculate per-cell percentage change of wetland cover they divided the 2001 wetland cover per cell by the estimate of 10-year wetland change.

Results: The proportional wetland cover varied from 0.0 to 5841.0 ha/100 km² across all 48 states considered. The area with the most wetland cover was the southeastern U.S. including portions of Alabama, Georgia, Florida, and North and South Carolina. The three areas with significant percentages of wetland cover were Florida, particularly in the northern part of the state and in the Everglades National Park, the floodplain of the Mississippi Valley, and parts of northern Minnesota and Wisconsin. The western U.S. had the least wetland cover with areas of less than 100 ha/100 km² in the Mojave and Sonoran Deserts. Between 2001 and 2011, wetland coverage decreased by approximately 481,500 ha. The highest percentage of loss was in the Great Plains region.

The models for the four animal groups showed regional hotspots where proportional wetland cover was positively or negatively correlated with species diversity. There was no consistent relationship between wetland cover and species variety across the entire 48 states, but on a regional scale there were correlations. Birds, reptiles, and endemic species groups all showed large areas of positively significant correlation with wetland cover while mammals and reptiles showed relatively larger negatively significant correlations.

Color-coded map of the United States. Yellow indicates a larger number of endemic species (83 is the highest amount). The colors change to shades of green, blue, and purple, with dark purple being the least amount, one species. The majority of the map is purple and blue. The southeastern region shows the most biodiversity, and all the yellow patches are in Florida, Georgia, South Carolina, Alabama, Mississippi and Louisiana.
Cumulative map of endemic amphibian, bird, mammal, and reptile species in the conterminous U.S. Note that the states with the most endemic species are Florida, Georgia, South Carolina, Alabama, Mississippi, and Louisiana.

Why is this study important? While wetlands all over the United States should be protected, certain areas are in a more delicate balance than others simply due to how many organisms rely on them. Knowing which regions have the most wetland cover and biodiversity can indicate where efforts of conservation and restoration should be particularly focused to have the most valuable impact. 

The big picture: Wetlands are important habitats and migratory stops for wildlife and provide essential services to the environment including carbon sequestration, water filtration, nutrient retention, and flood mitigation. The loss of wetlands in the U.S. to human activity and urban development has already been significant. The prevention of further damage has to begin with providing clear and concise information about the wetlands and the resources they provide. 

Citation: Dertien JS, Self S, Ross BE, Barrett K, Baldwin RF (2020) The relationship between biodiversity and wetland cover varies across regions of the conterminous United States. PLoS ONE 15(5): e0232052. https://doi.org/10.1371/journal.pone.0232052

New Species of Carnivorous Plant Discovered

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First record of functional underground traps in a pitcher plant: Nepenthes pudica (Nepenthaceae), a new species from North Kalimantan, Borneo

Martin Dančák, Ľuboš Majeský, Václav Čermák, Michal R. Golos, Bartosz J. Płachno, Wewin Tjiasmanto

Summarized by Michael Hallinan 

What data were used? 17 different specimens of a new species of pitcher plant (Nepenthes pudica) were examined from 5 different sites across the North Kalimantan province of Indonesia. This region is mountainous and covered with extensive rainforest.  The specimens were photographed, sampled, and then fixed in ethanol or dehydrated in preparation for further evaluation. In addition to these specimens, prey samples were also collected, including earthworms, insects, and insect larvae from inside the plants themselves. These were fixed in formaldehyde and further documented similar to the plant itself. 

Methods: The specimens went through three main stages of examination. First, the plants were photographed and compared to drawings and descriptions of other species within the genus Nepenthes. Next, the trap parts (used by the carnivorous plant to trap and collect prey) were examined under an electron microscope. Lastly, some of the traps were poured out and found to consist of insects, mites, and ticks. This content was identified and signs of digestion were documented, allowing the content to be labeled as either prey, or just organisms that live in the sediment and were unintentionally collected. 

Results: Typically the genus Nepenthes catches prey through a pitfall trap which has their prey fall into a pitcher-shaped cavity formed by a cupped leaf, where the plant then breaks them down through digestive juices. However, these traps are usually above ground or in water, with this trait only found in other genera such as Genlisea, Philcoxia, and Utricularia, though they use different entrapment strategies. The discovered species (Nepenthes pudica) features underground pitchers, where it catches and consumes prey such as mites, leaf litter-inhabiting beetles and ants. It is the first known pitcher plant species to use pitfall traps within the subterranean environment, containing traps of comparable size to the rest of the genus despite its subterranean nature. Typically, the pressure needed to form a cavity in soil is unsuitable for pitchers like these, which not only makes this find unique, but it also challenges our understanding of carnivorous plant feeding strategies.

Figure detailing four different images of the pitchers of the new species (Nepenthes pudica). The first image shows detail of the lower pitchers excavated from the soil. The second shows the lower pitchers under tree roots, while the third shows lower pitchers underneath a moss mat. Lastly, the fourth picture shows a set of lower pitchers extracted from a soil cavity. Generally the pitchers have a slightly curved opening with a fairly consistent width along the length of the pitcher. In addition, the pitchers feature a dark slightly purple red, with a green or white interior of the pitcher. Each of the pitchers is 7-11 cm in length and 3-5.5 cm in width.
Figure detailing four different images of the pitchers of the new species (Nepenthes pudica). The first image shows detail of the lower pitchers excavated from the soil. The second shows the lower pitchers under tree roots, while the third shows lower pitchers underneath a moss mat. Lastly, a set of lower pitchers extracted from a soil cavity. Each of the pitchers is 7-11 cm in length and 3-5.5 cm in width.

Why is this study important? This study is extremely important as identification is essential for protection. If we are more aware of which different species exist, we can better understand relative biodiversity as well as focus our conservation efforts. The discovery of this plant in particular allows a little bit more insight into understanding evolutionary adaptations of carnivorous plants which can potentially be applied to other plants within Indonesia’s ecosystem as well as carnivorous plants worldwide.

The big picture: 17 specimens of a new species of carnivorous plant were collected and further examined. Through a series of comparisons to known species within the genus as well as analysis of its prey and structure, it was determined to be a new species especially as a result of its unique underground traps. The traps typically seen within this genus of plants appear above ground or in water, which makes this species unique. This discovery allows us to better understand biodiversity in the region and gives us new insights into how we need to approach conservation. 

Citation:  Dančák M, Majeský Ľ, Čermák V, Golos MR, Płachno BJ, Tjiasmanto W (2022) First record of functional underground traps in a pitcher plant: Nepenthes pudica (Nepenthaceae), a new species from North Kalimantan, Borneo. PhytoKeys 201: 77-97. https://doi.org/10.3897/phytokeys.201.82872 

Conditions of essential desert plants

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Climate change effects on desert ecosystems: A case study on the keystone species of the Namib Desert Welwitschia mirabilis

By Pierluigi Bombi, Daniele Salvi, Titus Shuuya, Leonardo Vignoli, Theo Wassenaar

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? The welwitschia dwarf tree is a gymnosperm native to the Namib desert. It is considered a keystone species of the region, providing food, water, and shelter for the animals that live in the desert. Under the current threat of climate change, there is concern that certain parts of the welwitschia’s distribution range will no longer be suitable for their survival. 

Methods: The researchers spent ten days searching for W. mirabilis plants in the northernmost area of their traditional range. They recorded the plant locations (precise coordinates of the plant), health condition (based on leaf color to measure photosynthesis efficiency and chlorophyll content, using the classifications of good, average, poor and dead), reproductive status (whether or not the plant had cones), and plant size (diameter of the stem and leaf length) for each individual plant. Because the plants grow in clusters of four to 400, called stands, they recorded the proportion of healthy, average, poor, and dead plants in each stand, as well as the average size of the plants in each stand and proportion of reproductive to non-reproductive plants. 

Results: A total of 1330 welwitschia plants were found in 12 stands, across an area of about 215 km². The researchers found that that to be significantly smaller than what was previously considered their area of distribution. 

With regards to health conditions, most of the plants (50% total, 32–74% average in each stand) were considered ‘average’. Plants considered to be in ‘poor’ condition were 32% (range: 11–50%), those in ‘good’ condition were 10% (range: 0–30%) and seven percent of the plants were dead (range: 0–30%). Concerning reproductive status, 56% of the plants (range: 10–90% across the different stands) had cones. Size of the plants varied greatly when considered individually and in each stand. 

The overall status of the plants was considered consistent with their expected condition when taking into account the effects of climate change. The results suggested that ongoing climate change is negatively affecting the health status of welwitschia populations in the area and causing a reduction of the species’ distribution.

The black section is a squared-off area close to the northern border of Namibia with a small part of it touching the coastline. There are three red areas all relatively close to the shore, in line from north to south. Inside the black area there is a red area, and situated within that is the only blue area, which is very small compared to the black and red areas.
Larger map shows the study area (surrounded in black), the previously known species distribution (surrounded in red), and where the trees were found during the study (surrounded in blue). Insert map shows location of study, in northern Namibia.

Why is this study important? Welwitschia trees are essential to the Namib desert ecosystems and are good indicators for the overall health of the environment. Determining how they are responding to climate change could indicate what the future of the region will look like for the organisms that live there.

The big picture: While deserts are not usually thought of as teeming with life, they are important environments that house a lot of biodiversity in the form of plants and animals. The effects of global warming are and will continue to be particularly harsh on desert species. The ecosystems that exist there have to adapt to increasing temperatures that were already high to begin with, less rainfall where there was already very little, and more CO₂ in the atmosphere. These changes could greatly affect how the deserts all over the world function and whether or not the organisms that survive there will be able to continue to do so.

Citation: Bombi P, Salvi D, Shuuya T, Vignoli L, Wassenaar T (2021). “Climate change effects on desert ecosystems: A case study on the keystone species of the Namib Desert Welwitschia mirabilis.” PLOS ONE 16(11): e0259767. https://doi.org/10.1371/journal.pone.0259767