{"id":1373,"date":"2021-08-11T02:00:23","date_gmt":"2021-08-11T02:00:23","guid":{"rendered":"https:\/\/esa.org\/earlycareer\/?p=1373"},"modified":"2021-08-23T15:23:28","modified_gmt":"2021-08-23T15:23:28","slug":"paleo-litter-produces-greenhouse-gases","status":"publish","type":"post","link":"https:\/\/esa.org\/earlycareer\/2021\/08\/11\/paleo-litter-produces-greenhouse-gases\/","title":{"rendered":"Paleo litter produces greenhouse gases"},"content":{"rendered":"

By Alexis Heinz<\/em><\/p>\n

\"Red

Sphagnum<\/em> sp.<\/p><\/div>\n

Summary<\/strong><\/p>\n

While working as a laboratory manager for seven years in the department of Natural Resources at Cornell, I learned the invaluable experience of mentoring undergraduate students who had the opportunity to conduct research through the Hunter R. Rawlings, III Presidential Scholars Program.\u00a0 Professor Joseph B. Yavitt guided four different presidential scholars to research the \u2018Paleo Litter\u2019 topic in the time I managed the lab.\u00a0 In this article, I\u2019ll review a resultant paper, \u201cLeaf Litter Fuels Methanogenesis Throughout Decomposition in a Forested Peatland,\u201d (Corteselli et al., 2016).<\/p>\n

We examined the leaf litter decomposition rates of fifteen different tree species over four years.\u00a0 Precisely hand-mapping the project location kept technology out of the field and encouraged a greater appreciation of the unique forested wetland at Labrador Hollow.\u00a0 Redundantly and inertly labeling the litter bag samples ensured accurate retrieval even after plants and sphagnum attempted to bury the work.\u00a0 We then discovered more about the greenhouse gases produced by the different tree species because of variations in their internal constituents, i.e. soluble sugars and polysaccharides, pectin, lignin, hemicellulose, and cellulose.\u00a0 The most CO2 production from the remaining residue occurred for the incubated 164-day old litter, while the most CH4 production occurred for the incubated residue of 338-day old litter.\u00a0 Only the oldest 940-day old residue exhibited differences in CH4 production rates due to leaf type: angiosperms produced the most CH4, deciduous gymnosperms produced an intermediate amount, and evergreen gymnosperms produced the least.\u00a0 For CO2 production, leaf type did not have an influence on emissions, yet production decreased with increasing age of litter.\u00a0 A complex publication requiring the coordination of myself, four undergraduates (two scholars and two lab employees), a graduate student, and the advising professor, the findings were presented on Cornell\u2019s campus at a poster session.<\/p>\n

Commentary on the Methods<\/strong><\/p>\n

To introduce team participation, Professor Yavitt supervised the project.\u00a0 I helped organize the field plots, combining chemical protocols from multiple papers into the digestion procedure in addition to managing and performing lab tasks.\u00a0 James C. Burtis conducted statistical tests.\u00a0 The project included two additional students, Kristen MacFarlane, a work-study student in the lab from 2009 to 2013 and Kayla Jacobs, in the lab from 2010 to 2013.<\/p>\n

Kristen and I or Liz and I walked from campus to the Cornell Plantations to collect leaf litter for the fifteen tree species that were categorized according to functional group, i.e. deciduous angiosperm, deciduous conifer, and evergreen conifer.<\/p>\n

\"\"<\/p>\n

Contrary to the statement in the paper that the litter bags were of equal size, nylon mesh bag size ranged from a 4-inch to a 15-inch square including the 0.5-inch border outside of the impulse sealer seam.\u00a0 The goal was to ensure a total weight of 10-18-grams in each mesh bag with all the litter bags of all species having the same approximate thickness.\u00a0 The presence or absence of the rachis of compound leaves into the mesh bags may have contributed to species differences in the results.\u00a0 Some species such as P. mariana had to be handled carefully due to the size of the needles compared to the mesh size.<\/p>\n

Light blue plastic weed trimmer line was woven through the mesh edges to create a line of litter bags.\u00a0 Species location was randomized along each line from an old printed paper of random numbers.\u00a0 To ensure proper long-term identification, each line had a code and each species had a code.\u00a0 Line codes consisted of a series of loops (5) and knots (1) tied in the plastic line to indicate the line number, e.g. 7 = 1 loop + 2 knots.\u00a0 Each line was secured with a bamboo pole or similar object to note location.\u00a0 The entire plot was established with a field tape to clarify a central axis from which other locations were measured and mapped by hand.\u00a0 Old broom sticks or PVC pipes marked the start of each of the five blocks.\u00a0 Species were further labeled (aside from bag size) with two inert glass beads, e.g. Pinus strobus = two orange cat\u2019s eyes.\u00a0<\/p>\n

Sampling of the 5 x 15 = 75 lines of litter bags were collected via stratified random sampling, e.g. one line from each of the 5 blocks along an environmental gradient.\u00a0 In the final collection, all lines were still discoverable, even under significant organic matter accumulation and plant growth.\u00a0 After retrieval from the field, the bags, sometimes moist, sat in the low humidity lab for several days prior to being prepared for subsequent analysis starting with initial weights and percent moisture before incubations.<\/p>\n

To conserve laboratory resources, we tested old incubation jars for integrity by overfilling with N2, inverting under water, and agitating to stimulate the jar to leak.\u00a0 Non-leaking jars were used to collect greenhouse gas emission values via manual injection on the Shimadzu GC-14A.\u00a0 K. MacFarlane, K. Jacobs, and E. Corteselli all participated in collecting data from analysis on the GC.<\/p>\n

To calculate the fractions of different leaf components in the remaining residue, we repeatedly tested the complete leaf digestion protocol when calculating standard curves for eight concentrations each of arabinose, fructose, galactose, galacturonic acid, glucose, maltose, mannose, and xylose.\u00a0 To perform the sequential digestion (Table 2), I coordinated all four of us \u2013 working independently in sequence, not in parallel \u2013 to complete reagent addition, centrifugation, desalting, rinsing, and the colorimetric assay. \u00a0<\/p>\n

\"\"<\/p>\n

Discussion Response<\/strong><\/p>\n

The fractions listed in column B of Table 2 are present in different amounts and configurations depending on the leaf architecture of each species.\u00a0 Leaf architecture of deciduous compared to coniferous species could have a significant effect on the fractions, decomposition, and resultant greenhouse gas production.<\/p>\n

Lignin content was calculated from samples sent to Dairy One.\u00a0 Summary results were that hemicellulose decays fastest, then cellulose, and lignin decays slower (see Corteselli et al., 2016).\u00a0 According to the author, CH4 production seems more strongly dependent on structure, i.e. deciduous gymnosperms and angiosperms that have more soluble leaf constituents (smaller lignocellulose to pectin ratios from Corteselli et al., 2016, Figure 1, while evergreen gymnosperms have a higher lignocellulose to pectin ratio and less CH4 production).\u00a0 Although the author contends that wetland trees have more labile components that would produce CH4, the traits listed in Table 1 do not necessarily reflect that claim.<\/p>\n

The lack of CH4 production from the 164-day old residue was also discussed.\u00a0 Additional reasons could include the influential and\/or abundance of fungal communities on decomposition rates of lignin, available N to facilitate fungal activity, amount of sunlight due to percent tree canopy, and the ~6-month first time collection.\u00a0 To explain, if most collections were in 1-year intervals starting in early winter, the 6-month collection timepoint would have been in the spring when microbial activity \u2013 possibly in the peat soil \u2013 could be different.<\/p>\n

As a last note, pectin seems to be the operable leaf constituent in CH4 production (Table 4 from Corteselli et al., 2016).\u00a0 Microbial activity influenced by pectin that is available as structural components are successively removed is the basis of the leaf digestion laboratory protocol yet probably does not accurately reflect what occurs in the field.\u00a0 In situ digestion is likely more complex from multiple simultaneous processes.<\/p>\n

Prior to the study\u2019s completion, another Hunter R. Rawlings student, Anna Kryczka started working with Professor Yavitt in 2015 on the same topic before I departed from the lab in 2016 to complete graduate work.\u00a0 For more than a semester, the chem room in the lab was a geek relay endurance race that produced rewarding teamwork.\u00a0<\/p>\n

\u2014\u2014\u2014\u2014<\/p>\n

About the Author<\/strong><\/p>\n

From 2009 to 2016, in lieu of an immediate Ph.D., I managed a forest ecology laboratory at Cornell University in the department of Natural Resources for Professors Timothy J. Fahey and Joseph B. Yavitt.\u00a0 I supervised 32 undergraduate students, a few technicians, and helped visiting international professors and lab visitors.\u00a0 To improve working conditions in Bradfield Hall, I completed coursework in Environmental Psychology starting in 2014.\u00a0 In 2016, I left Cornell and accepted an offer from the University of Michigan, where I received two Master\u2019s degrees (M.S. Conservation Ecology and M. Landscape Architecture, 2019).\u00a0 After graduating, I worked as a landscape coordinator for UM\u2019s Alumni Association, summarizing land management goals in the 2019 Sustainability Plan for Camp Michigania located in Petoskey, Michigan.\u00a0 Then in March 2020, I founded Anagram ECO, LLC, acting as an ecological and community health advisor for neighborhoods and homeowners, reading the landscape as a field ecologist and offering design advice as a landscape architect who improves health.<\/p>\n

Copyright \u00a9 2021 Alexis K. Heinz<\/p>\n","protected":false},"excerpt":{"rendered":"

By Alexis Heinz Summary While working as a laboratory manager for seven years in the department of Natural Resources at Cornell, I learned the invaluable experience of mentoring undergraduate students who had the opportunity to conduct research through the Hunter R. Rawlings, III Presidential Scholars Program.\u00a0 Professor Joseph B. Yavitt guided four different presidential scholars to research the \u2018Paleo Litter\u2019…<\/p>\n","protected":false},"author":2225,"featured_media":1374,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-1373","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"_links":{"self":[{"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/posts\/1373","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/users\/2225"}],"replies":[{"embeddable":true,"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/comments?post=1373"}],"version-history":[{"count":0,"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/posts\/1373\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/media\/1374"}],"wp:attachment":[{"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/media?parent=1373"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/categories?post=1373"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/esa.org\/earlycareer\/wp-json\/wp\/v2\/tags?post=1373"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}