Plant and Insect Communities in a chronosequence of abandoned cranberry bogs December 20, 2017

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1 Omelchuck 1 Plant and Insect Communities in a chronosequence of abandoned cranberry bogs December 20, 2017 Project by: Chloe Omelchuck, Hampshire College Advisors: Linda Deegan and Christopher Neill, MBL Additional Investigators: Benjamin Hoekstra, Grinnell College and Michael Whittemore, Woods Hole Research Center Abstract The cranberry industry makes up a large portion of Massachusets economy, and cranberry bogs take up large portions of land in the state. However, in the past ten years many bogs have been abandoned, leaving them as natural areas. Little work has been done examining the ecology of these ecosystems. I examine plant and insect communities in a chronosequence of abandoned cranberry bogs. I sampled 2 plots for insects at 4 different cranberry bogs at two separate locations. I found 10 orders and 161 different species of insects throughout all the bogs, dominated by the order Diptera. Across the chronosequence, older bogs had greater abundance and less richness of insects than younger bogs. Plant communities were distinct between different bogs sites, and older bogs were more diverse. Abandoned cranberry bogs have great importance as resoirvoirs of diversity for inscect on the Cape, particularly for pollinators. Introduction Cranberry growing represents the largest portion of Massachusetts agricultural product, with total production representing 99.8 million in revenue in That production translates into 13,500 acres of active cranberry bogs in Massachusetts, and 62,000 total acres of land owned by cranberry growers mostly in Plymouth, Bristol, and Barnstable counties. As a whole, the business of cranberry production (including processing) accounts for 1.4 billion dollars in terms of total economic impact to the state. However, the industry has been in decline since 1999, when the industry suffered a huge collapse due to rising costs and competition from growers outside the state. Since then the industry has slowly shrunk resulting in large numbers of growers looking for exit strategies and abandoning their bogs to natural growth (Massachusetts Cranberry). Even when in production cranberry bogs provide a number of services like water

2 Omelchuck 2 filtration and conservation and recreational natural areas for residents and visitors (Massachusetts Cranberry), this is because every acre of cranberry bogs has 3-5 support acres or wetland and upland habitat. Abandoned bogs continue these functions with the added benefits of even greater plant diversity and providing more habitat for larger animals like birds and mammals. However, abandoned bogs are at risk for purchase by developers, mostly for housing, but would serve their communities better by remaining natural systems. Therefore, the most desirable exit strategy (ecologically speaking) is the purchase of land by towns or the state because it prevents development. Luckily, due to the state s active examination of the problem, this has been occurring and many former bogs are now public land. Aside from a general understanding of what services wetland ecosystems like abandoned cranberry bogs provide and their emotional/sentimental value as natural areas, very little research has been done on the actual ecology. The majority of research has been carried out on plant and animal communities in active bogs. Little to no work has been done on insect communities and soil characteristics. Furthermore, most bogs currently owned by local or state government have not been actively managed or restored, although there are a few examples and it is becoming more common. It is clear that there are large gaps in ecological knowledge surrounding abandoned cranberry bogs and that, considering the large number of bogs that have been abandoned and the potential for more, this knowledge is needed to properly manage them in a way that will be most beneficial for the ecosystem and community. My project aims to fill in some of these knowledge gaps by conducting plant and insect surveys of a chronosequence of abandoned cranberry bogs. My main question in this project is how does the time of abandonment in a chronosequence of abandoned cranberry bogs impact plant and insect communities?

3 Omelchuck 3 In addition to investigating current plant and insect communities, I will also try and keep in mind the potential futures of these bogs, one of which is restoration and/or active management. As part of cranberry growing bogs are slowly filled with layer after layer of sand which the cranberries are grown on top of. A system of channels is also built and the original water flow blocked in order to periodically flood the area. When the bogs are abandoned other plants begin to grow alongside the cranberries, but they are growing on the sand not the original substrate of the bog which is peat. In addition, the bog is drier because the water table is higher than one would expect in a natural bog, and the free-flowing water in the system probably doesn t have a through channel for any migrating fish. Restoration removes some of the sand, lowering the water table and removes any barriers to free-flowing water. It also re-mixes the underlying peat layer and remaining sand to create a substrate more like a natural bog. It then relies on the underlying seed bank in the soil to grow back a community of plants. Though I will not be sampling on any restored bogs I will also consider what effects there might be to plant and insect communities if abandoned bogs were to undergo restoration. Furthermore, this research will provide a basis for comparison if restored cranberry bogs are someday sampled for plants and insects. Methods and Experimental Design I target a chronosequence in bog history. For insect sampling the chronosequence consists of two bogs that have been abandoned for three years and two bogs that have been abandoned for ten years. For plant sampling the chronosequence is the same with the addition of a sampling of seeds from the seed bank at the current surface and at the peat layer. The current surface seeds provide some idea of what seeds might be currently in the seed bank which are not

4 Omelchuck 4 represented by plant sampling. In other words, what might grow if a disturbance or succession occurs. The samples from the peat, which represent the seed bank before cultivation of cranberries began, provide us with a snapshot of the plant community before cranberries were grown. In other words, the seed samples add two points to the chronosequence: past and future plant communities. From this additional chronosequence data I hope to gain some insight into the future of the plant community if restoration were to take place and what effects those changes to plant community might have on the insect community. If these bogs are sampled a second time once they are restored the seed bank results from this study can be compared to which plants actually occur to determine how much of an impact they have on what grows in the restored bog. In order to create the chronosequence four bogs were sampled; two which had been abandoned three years and two which had been abandoned ten years. The three year samples were collected at Tidmarsh from bogs A and D. The ten year samples were split between two sites. The first ten year bog sampled was Tidmarsh C and the second was the abandoned bog on the lower Coonamessett. Tidmarsh is the former site of Tidmarsh farms just outside of Plymouth MA (Figure 1). Lower Coonamessett is located in Falmouth MA and is currently undergoing restoration (Figure 2). For all samples collected the sample plots were 3 x 3 meter quadrats. At Tidmarsh ten plots were randomly selected within the bog area and plants, insects and seeds were sampled at all ten. At lower Coonamessett ten evenly spaced transects were created with four plots randomly selected along them for a total of forty plots. Plants and surface seeds were sampled from all forty plots. Insects were sampled from a random selection of two plots from each transect for a total of twenty. Peat seeds were sampled from the twenty plots which were

5 Omelchuck 5 not sampled for insects (Table 1). All plots are marked with GPS coordinates for their exact locations. Insect Sampling incorporates four different types of traps. All the traps are left out at the sample plots for a period of 72 hours (a longer time was used due to weather and time constraints on sampling). The first, and most well-known, is a pitfall trap (protocol courtesy of Margot McKlveen). Pitfall traps are 9oz cups dug into the ground that trap ground insects. The hold in the ground can be made using a trowel or similarly sized soil corer. The cup is placed so that the lip is flush with the surrounding soil. The insects fall into the traps and meet their demise in soapy water. At the end of the sampling period the cups are removed, labeled with the plot that they came from, and capped with lids. Back in the lab the samples are strained to remove the soapy water, rinsed with DI and 70% ethanol, then submerged in 70% ethanol and placed in the cold room to preserve them for identification. The second insect sampling method is bee bowls or pan trap. Bee bowls are small plastic cups (3.25 oz soufflé cups), filled with soapy water that attracts bees and other pollinators. The bowls are painted three colors that are attractive to bees white, fluorescent blue, and fluorescent yellow. Bees fly to the bowls, they land on the water expecting to find nectar, but meet their demise as the soap has broken the surface tension and the bees drown and fall to the bottom. Three cups were placed at each plot (1 of each color). When possible, bowls were placed in the sun to maximize visibility for pollinators. At the end of the sampling period all three bowls were poured into one 9 oz cup with a lid and labeled by plot. Back in the lab the samples are

6 Omelchuck 6 strained to remove the soapy water, rinsed with DI and 70% ethanol, then submerged in 70% ethanol and placed in the cold room to preserve them for identification. The yellow fly paper trap is a single sheet that is sticky on both sides and held up by a metal stake 8-10 inches off the ground. This trap is designed to catch flying insects that may have escaped the bee bowls. At the end of the sampling period the papers are stored in 16 oz plastic cups to prevent them from sticking to things and placed in the cold room to preserve them for identification. The white ground sticky trap is a paper sticky on only one side that folds over and links up at the top, forming a cylinder which is placed sideways on the ground for insects to crawl into. Three of these traps are placed in each plot. These traps are designed to capture insects travelling across the surface of bog vegetation which may have escaped the pitfall traps. At the end of the sampling period the sticky traps are stored in 16 oz plastic cups to prevent them from sticking to things and placed in the cold room to preserve them for identification. I identified the insects by order and occasionally family if possible. Due to the large number of insects that I found in the samples, I prioritized distinguishing between different species rather than figuring out precisely what they were. I photographed each species and checked new insects against the photos in order to maintain consistency. Though I collected samples from 10 plots at each Tidmarsh site and 20 plots at Coonamesset, I only identified insects from two plots at each site. Plants were identified by Chris Neill and Michael Wittemore and their percent cover estimated with the midpoints recorded.

7 Omelchuck 7 Seed Sampling is carried out using two methods.the first is using a soil corer to sample the top ten centimeters of soil. After collection the samples were placed in bags and refrigerated until further processing could be carried out. Peat is sampled using a somewhat more complex process. First, we dig a hole through the sand with the post hole digger down to the surface of the peat. Once the hole has been dug the depth of the sand is measured and recorded. Then we insert the russian peat corer into the hole and push it into the peat as far as it will go (no deeper than 50cm). After the corer has been filled the corer is closed to contain the sample, removed, then opened on plastic. If there is any residual sand at the top the length is measured and recorded as well as the total length of the core. The top ten centimeters of the core are cut away and placed in a labeled sample bag. Then the ten centimeters above the bottom five centimeters of the core are cut away and placed in a separate sample bag. Thus, for each plot (except Lower Coonamessett, where things are a little wonky) there are three seed samples; one for the surface seed bank, one for the upper peat seed bank, and one for the lower peat seed bank. The samples are refrigerated up until they are placed in the growth chamber and mixed with sand and potting soil in 7.7 cm round pots. Once the plants grow they are identified in the same method as the plant sampling. To pot the seed samples I determined the mass of soil for each sample that would take up 1 cm deep in volume at the top of my pots. I then weighed out that amount of sample and mixed it into a slurry, pouring it on top of a mixture of sand and potting soil. I placed the pots in a warm room heated to 30 degrees Celsius. I watered the pots twice daily and the lights were left on 12 hours, and turned off for 12 hours every day.

8 Omelchuck 8 Results In total I identified at least 10 different orders of insects and 161 species across the four sites. I classified the orders into functional groups for ease of examination. Orders themselves are not indicators of ecosystem function, however, among orders most insects share common traits that predict function. I classified Aranae, Anisoptera, and Coleoptera as predators (Figure 3). Diptera and Lepidoptera are pollinators (Figure 4). Orthoptera and Hempiptera are herbivores (Figure 5). Diplopoda are decomposers (Figure 6) and Acari are parasites (Figure 7). Hymenoptera is the most difficult to categorize since it is very variable containing species which function as predators, pollinators, herbivores, and parasites (Figure 8). Generally speaking, Hymenoptera which were captured in sticky and pitfall traps are ants (herbivores), while those caught in flypaper traps are wasps (predators and parasites), and those caught in bee bowls are bees and wasps (pollinators). The richness of this order seems to be split about 50/50 between ants and bees/wasps (Figure 9), which I keep in mind when looking at the data. Richness of species is an important measure of diversity, which shows the variety of species present. Overall richness is highest at Tidmarsh C, followed by Tidmarsh A, then Coonamessett and Tidmarsh D (Figure 10). The 3-year sites have a combined significantly greater richness than the 10-year sites (Figure 11). Breaking down richness by order, Diptera is the richest, followed by Hymenoptera, then Araneae. Tidmarsh C and A have the largest number of orders represented- each with eight, while Lower Coonamessett has the least with six. Anisoptera (Dragonflies) and Orthoptera (Crickets) are only found in the 3-year bogs. Diplopoda (Millipedes) are only found in the Tidmarsh C 10-year site (Figure 12). Abundance of species gives an idea of the producivity of the bogs and shows if any one order dominates the ecosystem. Overall abundance is highest at Tidmarsh C and Coonamesset.

9 Omelchuck 9 Abundance is significantly lower at Tidmarsh A and D in comparison to the 10-year bogs (Figure 13). In terms of order, once again, Diptera dominates (Figure 14). Interestingly, a single species of crane fly (spp. 37), makes up 20% of the individuals in Diptera and occurs in all sites, but is particularly prevalent at Coonamessett. Hymenoptera and Hemiptera trade off for the second most dominant orders depending on the site. No one species dominates Hymenoptera and its percentage abundance remains constant across the four sites. Hemiptera has a greater abundance relative to its richness, particularly at Tidmarsh C (Figure 14). It is interesting to note that in Hemiptera the candy-striped leafhopper (spp. 36) makes up 64% total abundance. However, the species does not occur in the three-year plots, only ten-year plots. Using Michael Wittemore s analysis of plants in the four sites, I concluded that Coonamesset has a plant community which is distinct from Tidmarsh. Within Tidmarsh, sites A and D have the same (or very similar) plant community. Some of the community characteristics of Tidmarsh A and D are shared with Tidmarsh C, which also shares community characteristics with Coonamesset. In terms of the spread of the plant community, the two ten-year sites are more diverse, while the two three-year sites are more clustered, showing a greater diversity of species in the 10-year sites (Figure 15). Not much grew in the seed sample pots. It proved very difficult to keep the peat pots from drying out. The slurry seemed to make the peat form a crust that dried out easily. In the future it might be best to mix the raw peat with a little bit of potting soil to improve water retention. The pots with peat in them didn t grow anything during the sampling period, however, some of the surface samples did sprout up some plants. However, they remained small and rather

10 Omelchuck 10 sparse with only two (apparent) species in a total of 10 pots, for a total of 15 individuals at the end of the sampling period (Table 2). Discussion The overall pattern in richness and abundance for insects across the chronosequence is that richness decreases while abundance increases. This is somewhat different than the expected results, which was that both richness and abundance would be greater in older bogs. Even more intriguing than the decrease in richness is the fact that abundance does not appear to follow this same trend, since most research shows that abundance generally increases with richness. This is not the case in plants, for which it seems that the communities follow the expected trends of greater diveristy over time (since cultivation). Once again, it is strange that the insect community does not follow the same dynamics as the plant community, as one would assume that a greater diversity of plants would support a greater richness of insect species that rely on them. There are several reasons why these dynamics in richness and abundance could be occuring Since the 10-year bogs have a more forest-like cover type it could be that this haitat is less attractive to pollinators (reducing richness), but it more protected from predators like Anisoptera and birds (increasing abudance). It is also possible that this is some sort of error in sampling. As mentioned, the 10-year bogs have a more-forest like cover type than the 3-year bogs, but the sampling methods were geared to collect insect up to only about a foot off the ground. This means that I may have missed species of insects dwelling in trees. Another reason for the low richness of 10-year sites may not be 10-year sites in general, but Coonamesset in particular. The average richness of the 10-year bogs is brought down by the low richness of Coonamesset. We know from the plant data that Coonamesset s plant community

11 Omelchuck 11 is distinct from Tidmarsh. It may be that the plant community at Coonamesset is not as attractive to insects. Another sampling error that may explain the reduced richness is that that the days that we sampled there were very rainy. The rain may have scared off some species and kept them undercover or inactive, so they didn t get trapped (reducing richness). In contrast, the Tidmarsh sites were sampled on clear sunny days that, while slightly colder, probobly brought out more insects. Out of all the functional groups, I would say that pollinators are the most important in the bog ecosystems. This is due to a number of conclusions from the data. Diptera, one of the pollinator species, dominates in both richness and abundance across all sites. Hymenoptera, though their functional group is only about 50% pollinators, is also a consistently dominant species. The bee bowls, which were meant to capture pollinators not only captured the majority of the Diptera species (further proving that Diptera s function is primarily pollinators), but captured the greatest abundance and richness of species out of all the trap types (Figures 16 and 17). Looking at a broder scope of functional groups, all of the bogs seem to support a variety of functions, particularly when is comes to pollinators, but also for herbivores (Hemiptera) and predators (Araneae). There are also functional groups which are supported more by 3-year bogs (Anisoptera and Orthoptera), and those which are supported more by 10-year bogs (Diplopoda). Overall, the abandoned cranberry bogs seem to support a wide variety of species, which is good for the argument of maintaining them as natural areas to increase the overall diversity of the Cape. In terms of managing bogs that are currently recovering, a good idea for bog diversity as the age of all recovering bogs gets older is to remove some of the shrubby and woody cover to

12 Omelchuck 12 allow for that more plainlike ecosystem and for species that live there. However, the mixture between the two cover types is a good thing for overall diversity since a greater number of habitat leads to a greater number of species. When it comes to active restoration of these bogs, it is unknown how such changes may affect the insect community. The seed samples would have shed greater light on this transition, however, there was not enough data to draw any conclusions about future plant communities. The principal differences between the insect communities of the two sites seem to spring from the transition from a more open and plain-like ecosystem to a more shrubby and forested one. A restoration would have the immidiate effect of creating a more plain-like ecosystem, but in later year would likely not become as foresty as the current bogs appear to be becoming. This would probobly be a good thing for pollinators. In the future, more insect survey should be done on both recovering and restored bogs to fill in the gaps in sampling discovered by this project and to examine how the transition to a more natural bog may change the insect community. Tables. Plot ID Types of Samples Collected T1-6 Vegetation, Surface Seed Bank, Insects T1-31 Vegetation, Surface Seed Bank, Insects T2-3 Vegetation, Surface Seed Bank, Insects T2-100 Vegetation, Surface Seed Bank, Insects T3-90 Vegetation, Surface Seed Bank, Insects T3-40 Vegetation, Surface Seed Bank, Insects T4-65 Vegetation, Surface Seed Bank, Insects T4-9 Vegetation, Surface Seed Bank, Insects T5-25 Vegetation, Surface Seed Bank, Insects

13 Omelchuck 13 T5-45 Vegetation, Surface Seed Bank, Insects T6-12 Vegetation, Surface Seed Bank, Insects T6-81 Vegetation, Surface Seed Bank, Insects T7-51 Vegetation, Surface Seed Bank, Insects T7-58 Vegetation, Surface Seed Bank, Insects T8-50 Vegetation, Surface Seed Bank, Insects T8-78 Vegetation, Surface Seed Bank, Insects T9-15 Vegetation, Surface Seed Bank, Insects T9-79 Vegetation, Surface Seed Bank, Insects T10-45 Vegetation, Surface Seed Bank, Insects T Vegetation, Surface Seed Bank, Insects T1-53 Vegetation, Surface Seed Bank, Peat Seed Bank T1-75 Vegetation, Surface Seed Bank, Peat Seed Bank T2-19 Vegetation, Surface Seed Bank, Peat Seed Bank T2-23 Vegetation, Surface Seed Bank, Peat Seed Bank T3-53 Vegetation, Surface Seed Bank, Peat Seed Bank T3-59 Vegetation, Surface Seed Bank, Peat Seed Bank T4-46 Vegetation, Surface Seed Bank, Peat Seed Bank T4-50 Vegetation, Surface Seed Bank, Peat Seed Bank T5-55 Vegetation, Surface Seed Bank, Peat Seed Bank T5-70 Vegetation, Surface Seed Bank, Peat Seed Bank T6-42 Vegetation, Surface Seed Bank, Peat Seed Bank T6-95 Vegetation, Surface Seed Bank, Peat Seed Bank T7-15 Vegetation, Surface Seed Bank, Peat Seed Bank T7-95 Vegetation, Surface Seed Bank, Peat Seed Bank T8-6 Vegetation, Surface Seed Bank, Peat Seed Bank T8-58 Vegetation, Surface Seed Bank, Peat Seed Bank

14 Omelchuck 14 T9-43 Vegetation, Surface Seed Bank, Peat Seed Bank T9-136 Vegetation, Surface Seed Bank, Peat Seed Bank T10-9 Vegetation, Surface Seed Bank, Peat Seed Bank T10-43 Vegetation, Surface Seed Bank, Peat Seed Bank Table 1. Lower Coonamessett sampling plots. Plot ID Depth Date Potted Spp. 1 12/3 Single Blade Spp. 2 12/3 Two- Leaf Spp. 1 12/10 Single Blade Spp. 2 12/10 Two- Leaf No. Individuals 12/3 T2-19 surface 11/17/ T3-52 surface 11/17/ T7-15 surface 11/17/ T8-6 surface 11/20/ T9-43 surface 11/17/ C5 surface 11/16/ A4 surface 11/17/ A6 surface 11/16/ D4 surface 11/16/ D8 surface 11/16/ Total Table 2. Results from the seed bank data. No. Individuals 12/10 Figures Figure 1. Tidmarsh. Three year sites are bogs A and D. Ten year site is bog E.

15 Figure 2. Lower Coonamessett. Omelchuck 15

16 Omelchuck 16

17 Omelchuck 17 Figure 3. Example of predators: (left to right) Araneae (spp. 153), Anispotera (spp. 145), Coleoptera (spp, 119). Figure 4. Example of pollinators: (left to right) Lepidoptera (spp. 155) and Diptera (spp.19). Figure 5. Example of herbivores: (left to right) Hemiptera (spp. 23) and Orthoptera (spp. 6). Figure 6. Example from Diplopoda (spp. 115), the only order of decomposers.

18 Omelchuck 18 Figure 7. Example from Acari (spp. 54), the only order of parasites. Figure 8. Example from Hymenoptera (spp. 130), classified as pollinators in this project. Figure 9. Richness of species by trap type. Hymenoptera caught in ground traps are almost all ants, while those caught in bee bowls and fly paper traps are ants and wasps. In terms of richness, the two kinds of Hymenoptera are split about 50/50.

19 Omelchuck 19 Figure 10. Total richness of species across all four sites. When simply divided between 3-year and 10-year sites, 3-year sites have 134 spp. and 10-year site have 123 spp., which is a significant difference. Figure 11. Richness pooled in 3-year and 10-year sites. Richness in the 10-year sites is significantly less than the 3-year sites. Figure 12. Richness by order. The richness of Diptera is significantly lower at Coonamesset and Tidmarsh D in comparison to the other two bogs. The richness of Hymenoptera is significantly higher at Tidmarsh C in comparison to the other three bogs. The richness of Araneae is significantly lower at Coonamesset in comparison to the other three bogs.

20 Omelchuck 20 Figure 13. Total abundance of individuals across all four sites. Figure 14. Total abundance of individuals by order across all four sites.

21 Omelchuck 21 Figure 15. Plant Communities at the four bog sites. Note that Tidmarsh A and D are pooled together because of how similar they are. The more oblong shapes of the two 10-year sites shows that they are more diverse.

22 Omelchuck 22 Figure 16. Richness of species across trap types. Figure 17. Abundance of species across trap types. Citations The Massachusetts Cranberry Revitalization Task Force Final Report. MA Department of Agricultural Resources. May 20, 2016.