Assessments of Organic Carbon Stocks in Wetlands by Citizen Scientists - Guideline and Protocols

Assessments of Organic Carbon Stocks in Wetlands by Citizen Scientists Guideline and Protocols Version 1.1 10.10.2025 Citation: Weigelhofer, G., Wijffels, O., Rosenberger, C., Ramadan, H., Alphart, J., Novkovic, M., Cvijanović D. (2025) Assessments of Organic Carbon stocks in Wetlands by Citizen Scientists. Guideline and Protocols. Horizon Europe Project Restore4Life (101112736). 10.5281/zenodo.17328601 Content CHAPTER 1: BACKGROUND ............................................................................................................................................................ 3 CHAPTER 2: WETLANDS AS ESSENTIAL CARBON STORES HELP REGULATE THE CLIMATE ................................. 4 CHAPTER 3: SOIL ORGANIC CARBON IN SOILS WITH SHALLOW ORGANIC LAYER (FLOODPLAIN FOREST, MEADOWS) ........................................................................................................................................................................................... 5 3.1. PROTOCOL ............................................................................................................................................................................... 5 3.2. CALCULATIONS....................................................................................................................................................................... 8 3.3. FOR SCIENTISTS ....................................................................................................................................................................19 CHAPTER 4: SOIL ORGANIC CARBON IN SOILS WITH DEEP ORGANIC LAYER (PEATLANDS) .......................... 20 4.1. PROTOCOL ............................................................................................................................................................................ 20 4.2. FOR SCIENTISTS ..................................................................................................................................................................... 4 CHAPTER 5: ORGANIC CARBON IN TREE BIOMASS............................................................................................................. 5 5.1. PROTOCOL TREE HEIGHT AND CIRCUMFERENCE ................................................................................................... 5 5.2. FOR SCIENTISTS ..................................................................................................................................................................... 8 5.3. PROTOCOL BITTERLICH METHOD .................................................................................................................................. 11 CHAPTER 1: BACKGROUND Monitoring Ecosystem Services (ES) provided by wetlands is crucial for assessing the state of the wetlands, their changes over time, and the impacts of conservation and restoration measures. The engagement of non-experts as Citizen Scientists can support this ES monitoring by delivering large amounts of data otherwise not (easily) available. Additionally, Citizen Science helps raise awareness among local people about the significance of wetlands for human well-being, thereby enhancing citizens’ stewardship. In the Horizon Europe Project RESTORE4LIFE, 101112736 (https://restore4life.eu/ ), we have created a toolbox for monitoring ES of wetlands (Deliverable D3.5), covering both geospatial and on-the-ground methods (publicly available from Dec 2025on our webpage and Zenodo). One focus was on developing Citizen Science protocols for on-the-ground measurements that provide reliable and valuable data for wetland assessments. Various Citizen Scientists helped us test the developed protocols regarding their intelligibility, user-friendliness, and applicability before release. To assess the quality and explanatory power of the data collected by Citizen Scientists, we compared them with data collected by scientists using more advanced methods. The results of these quality checks can be found in our toolbox D3.5. The following topics were covered and published separately: (1) water quality, (2) organic carbon storage in tree biomass and wetland soils, (3) plant diversity, and (4) recreational and educational services. Each published document consists of several parts: Citizen Scientists' protocol(s) for assessing data in the field; Citizen Scientists' protocol(s) for indoor analyses (if applicable); Citizen Scientists' protocol(s) for calculations (if applicable); and a guideline for scientists on further data processing. The current document addresses the Potential of wetlands to store organic carbon in aboveand below-ground biomass. CHAPTER 2: WETLANDS AS ESSENTIAL CARBON STORES HELP REGULATE THE CLIMATE Wetlands are dynamic ecosystems that store significant amounts of organic carbon in tree biomass and soils. This is due to the high productivity of the vegetation and the frequent water saturation of the soils, which slows the decomposition of organic material, helping preserve carbon. This storage helps regulate atmospheric CO₂ levels and mitigate global warming. Wetland degradation occurs due to drainage for agriculture or development, damming or water diversion, overgrazing, logging, or peat extraction. These activities disturb waterlogged conditions, which are crucial for storing carbon. As a consequence of wetland degradation, wetlands change from carbon sinks to carbon sources. Drainage of peatlands, for example, can release up to 20–40 tonnes of CO₂ per hectare per year. This makes wetland conservation and restoration essential strategies in global climate mitigation efforts. Your contribution to assessing the organic carbon storage in wetlands significantly supports wetland restoration. Thank you CHAPTER 3: SOIL ORGANIC CARBON IN SOILS WITH SHALLOW ORGANIC LAYER (FLOODPLAIN FOREST, MEADOWS) 3.1. PROTOCOL MATERIALS:  Soil sampler (drill) or shovel  Plastic bags (1 L)  Spoons  Measuring stick  Small water bottle  if possible, small cool box  For indoor analyses: mason jar, balance, oven (or dry place); aluminum foil (for oven drying), two measuring cylinders;  For advanced indoor analyses: balance, clean 500 mL plastic beakers, coffee filters, funnel, pH test strips, nitrate and phosphate test kits OUTDOOR TASKS: 1. Site characteristics: Use your smartphone's GPS to determine your location's coordinates and record them in the form. Take a picture of the site. 2. Sampling: Remove plants and litter from the ground. If you have a soil drill, drive the drill to a depth of 15 cm and carefully draw the soil sample. If you have a shovel, dig a hole of approx. 15 cm depth and 20x20 cm area into the soil so that you can see the vertical layers. 3. Soil profile: Measure and record the depth of the upper dark (organic-rich) layer. Take a picture of the soil profile together with the measuring stick. 4. Soil type: Carefully remove a sample the size of a walnut from the lower, brighter layer. If the sample is dry, wet it slightly. Knead the sample between your fingers into a sphere. Then, try to make a cylinder. Now, rub the sample carefully between your fingers. Based on your observations, determine the soil type according to the table given below and record it in the soil form. 5. Sampling for indoor analyses: Place one fresh sample from the upper dark layer and one from the lower lighter soil layer in separate plastic bags. The samples should be the size of an apricot. Label the bags with the location's name, the date, and the layer (upper/lower). Store the samples in a cool, dark box or bag until further analysis in the lab. INDOOR TASKS: Always keep the label attached to the sample so that you can identify it! 6. Measure the volume of the sample: Place the closed plastic bag with the sample into the measuring cylinder. Fill a second cylinder with water and note the starting volume. Now, pour water from the second cylinder into the first cylinder until the soil sample is entirely covered. Record the volume of water added and the total volume (soil + water). Subtract the water volume from the total volume to estimate the sample volume. 7. Dry weight and moisture content: Remove the soil from the bag and weigh it (wet weight). Dry the samples in an oven (75°C for 24 hours) or the sun (for four days) and weigh them again (dry weight). 8. Organic content – Jar experiment Fill the remaining soil sample into a mason jar (leave one spoonful aside for the advanced analysis). Then, pour water into the jar. Shake for 3 minutes and let the soil particles settle for 1-2 days. Observe the layers that form: The organic matter floats on top of the water (dark colour). At the bottom, you can see the mineral particles: the lowest is sand, followed by silt and then clay (see picture). Measure the height of each layer with a ruler. Remove the organic layer on top of the water carefully using a spoon or forceps, dry and weigh it. Finally, dry the remaining sample in the jar and weigh it. ADVANCED INDOOR TASKS: 9. Soil chemistry: Add one spoonful of soil to approximately 50 mL of distilled water and stir for 1 minute. Filter the mixture through a coffee filter into a clean beaker. Wash the funnel and use new coffee filters for each new sample. Use test strips to measure various parameters such as pH, nitrate, and hardness. Organic particles Clay Silt Sand 3.2. CALCULATIONS 1. Calculate soil moisture content SM (%): Subtract the dry weight of the sample from the initial weight to get the water weight. Then, divide the water weight by the initial weight and multiply by 100 to get the soil moisture (in %): Soil moisture SM (%) = (Wet weight – dry weight) / wet weight x 100 2. Calculate soil bulk density BD (g/dm³): Important: You have probably measured the volume in litres or millilitres. Convert volumes into cubic decimeters (dm³) for the calculations (1L = 1 dm³). Then, divide the dry weight (g) by the sample volume (dm³). Soil bulk density BD (g/dm³) = Dry weight (g) / sample volume (dm³) 3. Calculate percentage of soil components (%) – Jar experiment: In addition to the estimation in the field, you can use the data from the jar experiment to determine the soil type. Divide the height of each layer by the total height and multiply it by 100: Height of sand layer / total height of soil layers x100 = % sand Height of silt layer / total height of soil layers x 100 = % silt Height of clay / total height of soil layers x 100 = % clay 4. Calculating the Organic carbon content OC (%) – Jar experiment: Calculate the total dry weight TW of the sample in the jar by adding the dry weight of the organic matter to the dry weight of the rest of the sample. Total dry weight TW (g) = Dry weight OM (g) + Dry weight rest of sample (g) Divide the dry weight of the organic matter by 2 to get the amount of organic carbon OC. Most organic matter has a carbon content of around 50%. Organic carbon OC (g) = Dry weight OM (g) / 2 Finally, divide the organic carbon OC by the total dry weight TW Percentage of organic carbon OC1 = dry weight OC / total dry weight TW 5. Calculating the Soil Organic Carbon Storage (kg/m²) Multiply the soil bulk density (BD) by the percentage of organic carbon OC to get the organic carbon concentration (g/dm3). Organic carbon concentration OCC (g/dm³) = Soil bulk density BD (g/dm3) x Percentage of Organic carbon OC 1 The percentage is given as a dimensionless fraction here. So, 20% = 0.2, 50% = 0.5, 100% = 1. Sand Loam Clay 0 - 10% clay 10 - 30% clay 50 - 100% clay 0 - 10% silt 30 – 50% silt 0 – 45% silt 80-100% sand 25 – 50% sand 0 – 45% sand SOIL FORM Name Date Time Location GPS Depth of the peat (cm) Degree of Humification (Van Post-Scale) Sample volume (L) Wet weight (g) Dry weight (g) 3 4 4.2. FOR SCIENTISTS The project “Tracking the Color of Peatlands” (University of Plymouth) monitors changes in peatland green leaf phenology (i.e. how the peatlands change colour over the course of the year) using smartphone photography and colour recognition. Thus, CS do not need to go on the peatland but can track changes from walking paths. https://www.plymouth.ac.uk/research/plymouth-peatland-researchgroup/tracking-the-colour-of-peatlands-project 11.10.2025 5 CHAPTER 5: ORGANIC CARBON IN TREE BIOMASS 5.1. PROTOCOL TREE HEIGHT AND CIRCUMFERENCE MATERIALS:  Flexible 2 m tape  Smartphone  Stick of at least an arm's length  Tree biomass form OUTDOOR TASKS: 1. Site Characterisation: Select 3-5 sites within your survey area. The sites should be easily accessible and representative of the region. Each site should have an area of approximately 20 m in length and 10 m in width. For tree height estimations, you must see the entire tree from approximately 20 m. Thus, in dense forests, select a site along a path. Take a picture of each site and note the GPS data and the date and time of the survey in the “Tree biomass” form. 2. Circumference and tree species: Measure the circumference of each tree within this site via the “Diameter-atBreast-Height method” (see below). Identify each tree species using the App "Flora incognita”. Note both the species names and circumferences in the “Tree biomass” form. 3. Tree height: Select 1-2 trees of average height. Estimate the tree height using the “Triangle method” (see below). With the mean height and the exact circumference, we can estimate the tree's biomass. 6 "Diameter-at-Breast-Height" Method to determine the circumference of a tree The "Diameter-at-Breast-Height" method is a simple procedure that quickly provides information about a tree trunk's mean circumference and diameter. It can be used for both living and dead trees. a. Stand in front of the tree and have your measuring tape ready. If the tree is on a slope, stand between the uphill and the downhill side of the tree. b. Measure 1.37 meters upward from the ground. A height of 1.37 meters represents the mean tree diameter. If the tree stands on a slope, measure from the mid-point between uphill and downhill (see picture). c. Now place the measuring tape at the measured height around the trunk and measure the circumference of the tree trunk. Ensure the measuring tape is tightly held against the bark and wraps as circularly around the trunk as possible. d. Calculate the mean tree diameter by dividing the measured circumference by 3.14. 7 “Triangle Method" to determine the Tree Height The Forester's Triangle method allows you to quickly and easily determine the height of trees. a. Choose 2-3 trees that are easy to access. It is essential that you can see the entire tree from bottom to top. Make sure that the surrounding terrain is level. b. To estimate the tree height, you need a long, straight stick. The length of the stick should equal the length of your outstretched arm. c. Hold the stick with your outstretched arm in a vertical position so that a right-angled triangle is formed between your arm and the stick (see picture). Stand in front of the chosen tree and walk backward from the tree in a straight line until the length of your stick roughly matches the height of the tree. From your position, the base of the stick just above your hand should be approximately the same height as the base of the trunk. The stick's tip should be roughly the same height as the treetop. d. Once the stick and tree are equivalent, mark the spot where you are standing and measure the distance to the tree. You can do this either with a long (2030 m) measuring tape or by pacing the distance between this spot and the tree. For pacing, take as large steps as possible, as they roughly correspond to one meter, allowing you to estimate the distance to the tree better. e. The distance measured corresponds to the height of the tree. Distance 8 5.2. FOR SCIENTISTS You can estimate the carbon stock and sequestration of a tree via its height, diameter, and density using the following formulas: 1. Total Volume V: V (m3) = 3.14 x r2 x h x 1.4 Where r=radius of the stem at 1.37 m height (m) and h=tree height (m). The factor 1.4 accounts for the root and canopy biomass (Shadman et al. 2022). 2. Total Carbon Content (OC): For the total carbon content, multiply the tree's total volume by the wood density and the organic carbon content. The density of dry wood depends on the tree species (see list below). For rough estimations, take a mean of 530 kg/m3. The carbon content is 50% of the dry mass. OC (kg) = Total Volume x Density x 0.5 3. CO2 sequestered: The weight of CO2 sequestered in trees is determined by the ratio of CO2 to C, which is 44/12 = 3.67. Multiply TC by 3.67 to estimate the CO2 sequestered. CO2 sequ (kg) = OC × 3.67 Note that this value represents the CO2 sequestered in the entire lifetime of the tree. To ascertain the annual CO2 sequestration rate, divide the total CO2 sequestered by the tree’s age (if available). 4. Ellenberg’s indicator values These indicators provide information about the ecological requirements of tree species regarding light, temperature, moisture content, soil acidity, and Nitrogen 9 content, to characterize the site. Unfortunately, these indicators are available only in German and only for Central Europe at https://statedv.boku.ac.at/zeigerwerte/. The Flora incognita also offers species traits in the descriptions of the species. REFERENCES https://bigtrees.forestry.ubc.ca/measuring-trees/. 27.06.2024 Vries, W. et al. (2003). Intensive Monitoring of Forest Ecosystems in Europe: Technical Report 2003. Shadman, S, et al. (2022) The carbon sequestration potential of urban public parks of densely populated cities to improve environmental sustainability. Sustainable Energy Technologies and Assessments 52, 102064. https://doi.org/10.1016/j.seta.2022.102064. 10 Wood densities for common trees. From Vries et al 2003 11 5.3. PROTOCOL BITTERLICH METHOD The Bitterlich method (1984) is a forest measurement technique used to determine the basal area of trees per hectare (m²/ha). This method involves selecting multiple systematically distributed points in the forest. The technique can substitute the measurement of the circumference and be used to calculate the existing timber volume if multiplied by the average tree height. MATERIALS:  Measuring tape (100 cm)  Relascope: 50 cm rope and 2x4 cm plate (or you use your arm length and your thumb)  Smartphone  OUTDOOR TASKS: 1. Determine the basal area count factor CF: CF = (W × 50 ÷ L)² where W is the width of the relascope (or thumb) and L is the length of the rope (or arm). Example: For a stick with a length of 50 cm and a plate width of 2 cm, the count factor is calculated as follows (calculate in the same way for arm and thumb): 2. Select the first sampling point in the forest. Hold one end of the rope to your eye and attach the other end to the plate in a horizontal line. The rope is fully stretched. L W