Recipient Organization
STATE UNIV OF NEW YORK
(N/A)
SYRACUSE,NY 13210
Performing Department
Environmental & Forest Biology
Non Technical Summary
Forest floor mosses are a major component of biodiversity, biomass and biogeochemical cycles(cycling of plant nutrients, pollutants, and water) in temperate high-elevation conifer forests, and yet, theireffects on ecosystem functions are not well understood. During the past several decades, acidic andmercury deposition have affected both mineral dynamics and tree regeneration processes in spruce-firforests. Since mosses can affect the chemical and moisture conditions at the microsite scale relevant fortree seedling establishment, survival and growth, we would like to elucidate the mineral dynamics ofground level mosses, its drivers and rates. If funded, this Seed Grant will provide the foundation for asubsequent larger proposal to explore how mosses can mediate interactions among biogeochemical andclimate controls over forest regeneration. This research, which takes place on Whiteface Mountain in theAdirondack Park, NY, takes advantage of an existing extensive historical data set on vegetationcharacteristics, atmospheric deposition, and a microclimate monitoring network.Establishment, vigor, and early survival of tree seedlings occur at fine spatial scales (Grenfell et al.,2011 ), where micro climatic factors and mineral nutrition can be regulated by mosses (Nasr & Arp, 2011 ).At these scales, mosses respond to and affect microclimate, especially by buffering moisture due to theirsignificant water storage capacity (Michel et al., 2012). In addition, mosses can play an impmtant role inaffecting the fate of minerals originating from atmospheric deposition (Schri:ider et al., 2010), such asplant nutrients (e.g., nitrogen) and pollutants (e.g., mercury). Mosses can trap, store and then slowlyrelease minerals that will become available to other plants in the forest (e.g., Nadkarni, 1984). Thus,understory mosses can potentially buffer moisture deficits of tree seedlings, and also provide a readilyaccessible mineral solution rich in plant nutrients and pollutants.Despite the abundance of correlative studies between bryophyte cover and tree seedling abundance(e.g., Dovciak et al. 2008), the mechanisms causing the relationships, either positive or negative, betweenbryophytes and tree seedlings remain unclear (Soudzilovskaia et al., 2011 ). Better understanding of the mechanisms that govern interrelationships between mosses, water and mineral cycling, and tree seedlingsis particularly important in high-elevation forests of the temperate zone, where moss is frequently themost dominant ground cover and a critical substrate for the establishment of tree seedlings.In this context, three factors make Whiteface Mountain (Adirondacks, N.Y.) an ideal location toexplore the biogeochemical linkages between mosses and tree seedlings that are likely to berepresentative of more widespread ecological processes in high-elevation forests of northeastern US. Thehigh-elevation forests on Whiteface Mountain are dominated by red spruce (Picea rubens) and balsam fir(Abies balsamea), much like elsewhere in the northeastern US. In fact, Whiteface Mountain has beenselected in the l 980's as a site for collecting long term data on atmospheric deposition (acid rain) andforest compositional change to characterize regional phenomenon of red spruce decline occurring acrossthe north-eastern US at that time (e.g., Battles et al. 2003). Historical vegetation plots and associated dataseries are available for forest vegetation and atmospheric conditions, collected and stored by theAtmospheric Sciences Research Center (ASRC), and for the chemistry of wet depositions (rain, cloud andsnow), collected by the Adirondack Long Term Monitoring program (ALTM). In the proposed project, wewill integrate the results obtained from the detailed micro-scale analyses covered by the proposed SeedGrant with the above landscape-scale data to understand potential ecological implications of understorymosses on spruce-fir forest regeneration under conditions dominated by a warmer climate and a netmercury accumulation.While acidic deposition has declined during the last decades, mercury deposition has become acurrent concern in the northeastern forests (Townsend et al. 2014). Mercury dynamics have beenintensively studied in the Adirondacks, but some questions remain unsolved and understory mosses seemto be involved. Spruce-firforests receive higher inputs of mercury via throughfall, and have lower lossrates, compared with the immediately adjacent ecosystems in the alpine zone and hardwood forests Oustabove or below spruce-fir forests). Yet, the pool of mercury in soils of spruce-fir forests is smaller thanexpected based on inputs (Blackwell et al., 2014). In addition, humid conditions associated with mossesmay favor chemical interactions between dissolved organic matter (DOM) and mercury. These interactions affect the production and bioaccumulation of methyhnercury across trophic networks(Ravichandran, 2004) and may have further negative impacts on the whole ecosystem. Our proposal isunique and significant because we will study the biogeochemical linkages between mosses and treeseedlings by focusing on nitrogen and mercury and on their relevant molecular forms for seedlingdevelopment, i.e., nitrates and methylmercury (the toxic form of mercury).Our overall goal is to expand the understanding of the effects of understory mosses on the retentionof moisture and minerals as a pathway to elucidate moss effects on forest regeneration in spruce-firforests. We would like to answer these questions: (i) What is the size of the pools of water, nitrogen, andmercury associated with understory mosses and how do they change spatially and temporally? (ii) Do treeseedlings established on mossy substrates differ in water stress and mineral content from those associatedwith substrates without mosses? (iii) How can changing climate potentially affect water and mineralrelations ofunderstory mosses and regeneration in spruce-fir forests? Hence, we will:1. Quantify nitrogen, nitrates, mercury and methylmercury stored by understory mosses, anddescribe changes in their concentrations over the growing season.2. Contrast levels of moisture stress and mineral content of tree seedlings established on substrateswith and without mosses and relate this to seedling survival.3. Model potential impacts of climate change trends expected in the Northeastern spruce-fir forestson moisture and mineral pools ofunderstory mosses, as a first step toward understanding howclimate change may affect forest regeneration at the micro-site scale.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Our overall goal is to expand the understanding of the effects of understory mosses on the retentionof moisture and minerals as a pathway to elucidate moss effects on forest regeneration in spruce-firforests. We would like to answer these questions: (i) What is the size of the pools of water, nitrogen, andmercury associated with understory mosses and how do they change spatially and temporally? (ii) Do treeseedlings established on mossy substrates differ in water stress and mineral content from those associatedwith substrates without mosses? (iii) How can changing climate potentially affect water and mineralrelations ofunderstory mosses and regeneration in spruce-fir forests?
Project Methods
1. Quantify nitrogen, nitrates, mercury and methylmercury stored by understory mosses, anddescribe changes in their concentrations over the growing season.2. Contrast levels of moisture stress and mineral content of tree seedlings established on substrateswith and without mosses and relate this to seedling survival.3. Model potential impacts of climate change trends expected in the Northeastern spruce-fir forestson moisture and mineral pools ofunderstory mosses, as a first step toward understanding howclimate change may affect forest regeneration at the micro-site scale.