Nitrogen Cycling in the Americas: Natural and Anthropogenic Influences and Controls

275 Pages·2006·2.394 MB·English

by  Luiz A. Martinelli, Robert W. Howarth (auth.), Luiz A. Martinelli, Robert W. Howarth (eds.)

NITROGEN CYCLING IN THE AMERICAS:NATURAL AND
ANTHROPOGENIC INFLUENCES AND CONTROLS
NITROGEN CYCLING IN THE
AMERICAS: NATURAL AND
ANTHROPOGENIC INFLUENCES
AND CONTROLS
Edited by
LUIZ A. MARTINELLI
Cena-University of São Paulo, Brazil
&
ROBERT W. HOWARTH
Cornell University, U.S.A.
Reprinted fromBiogeochemistry Volume 79, Nos. 1–2, 2006
123
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ISBN 1-4020-4717-7
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Table of Contents
LUIZ A. MARTINELLI & ROBERT W. HOWARTH / Preface 1–2
LUIZ A. MARTINELLI, ROBERT W. HOWARTH, ELVIRA
CUEVAS, SOLANGE FILOSO, AMY T. AUSTIN,
LORETA DONOSO, VERA HUSZAR, DENNIS KEENEY,
LUCIENE L. LARA, CARLOS LLERENA, GEORGE
McISSAC, ERNESTO MEDINA, JORGE ORTIZ-ZAYAS,
DONALD SCAVIA, DAVID W. SCHINDLER, DORIS
SOTO & ALAN TOWNSEND / Sources of reactive
nitrogen affecting ecosystems in Latin America and the
Caribbean: current trends and future perspectives 3–24
DAVID W. SCHINDLER, PETER J. DILLON & HANS
SCHREIER / A review of anthropogenic sources of
nitrogen and their effects on Canadian aquatic
ecosystems 25–44
AMY T. AUSTIN, GERVASIO PIÑEIRO & MARINA
GONZALEZ-POLO / More is less: agricultural impacts on
the N cycle in Argentina 45–60
SOLANGE FILOSO, LUIZ ANTONIO MARTINELLI, ROBERT
W. HOWARTH, ELIZABETH W. BOYER & FRANK
DENTENER / Human activities changing the nitrogen
cycle in Brazil 61–89
JULIO A. BAISRE / Assessment of nitrogen flows into the
Cuban landscape 91–108
JORGE R. ORTIZ-ZAYAS, ELVIRA CUEVAS, OLGA L.
MAYOL-BRACERO, LORETO DONOSO, IVONNE
TREBS, DEBORA FIGUEROA-NIEVES & WILLIAM H.
MCDOWELL / Urban influences on the nitrogen cycle in
Puerto Rico 109–133
MERCY J. BORBOR-CORDOVA, ELIZABETH W. BOYER,
WILLIAM H. MCDOWELL & CHARLES A. HALL /
Nitrogen and phosphorus budgets for a tropical
watershed impacted by agricultural land use: Guayas,
Ecuador 135–161
R.W. HOWARTH, D.P. SWANEY, E.W. BOYER, R. MARINO,
N. JAWORSKI & C. GOODALE / The influence of climate
on average nitrogen export from large watersheds in the
Northeastern United States 163–186
DONALD SCAVIA & SUZANNE B. BRICKER / Coastal
eutrophication assessment in the United States 187–208
M.M.C. BUSTAMANTE, E. MEDINA, G.P. ASNER,
G.B. NARDOTO & D.C. GARCIA-MONTIEL / Nitrogen
cycling in tropical and temperate savannas 209–237
VERA L.M. HUSZAR, NINA F. CARACO, FABIO ROLAND &
JONATHAN COLE / Nutrient–chlorophyll relationships in
tropical–subtropical lakes: do temperate models fit? 239–250
JEAN P. H. B. OMETTO, JAMES R. EHLERINGER, TOMAS
F. DOMINGUES, JOSEPH A. BERRY, FRANÇOISE Y.
ISHIDA, EDMAR MAZZI, NIRO HIGUCHI, LAWRENCE
B. FLANAGAN, GABRIELA B. NARDOTO & LUIZ A.
MARTINELLI / The stable carbon and nitrogen isotopic
composition of vegetation in tropical forests of the
Amazon Basin, Brazil 251–274
Biogeochemistry(2006)79:1–2 (cid:2)Springer2006
DOI10.1007/s10533-006-9012-z
Preface
This special issue presents the products of three workshops designed to
compare differences in nitrogen cycling between tropical and temperate eco-
systems across the Americas, as well as differences in how human societies
shave transformed the nitrogen cycle according to economic, social and cul-
tural characteristics of the diverse countries of the Americas. The first work-
shopon‘‘Nfluxesandprocessesintropicalandtemperatesystems’’washeldin
the city of Ubatuba, State of Sa˜o Paulo, Brazil, in March 2003. From this
workshop,astrong consensus developedtoforman ongoing‘‘InterAmerican
NitrogenNetwork.’’Towardsthisend,twomoreworkshopswereheld,onein
San Juan, Puerto Rico in May 2004, and one in May of 2005 in the city of
Brası´lia,Brazil. Thisefforttobuild theInterAmericanNitrogenNetwork isa
joint effort of the Latin American Nitrogen Center and the North American
Nitrogen Center, two of the five continental-scale regional centers of the
International Nitrogen Initiative (INI) created in 2003 by SCOPE and the
IGBP. The INI’s main objective is ‘‘to optimize nitrogen’s beneficial role in
sustainable food production and minimize nitrogen’s negative effects on
human health and the environment resulting from food and energy produc-
tion.’’WehopethereaderswillagreewithusthatthisissueofBiogeochemistry
isanexcellentstartfortheInterAmericanNitrogenNetworkandtheeffortsof
the INI in the Americas.
ThefirstpaperpresentedinthisissuebyMartinelliandotherparticipantsof
the San Juan workshop is an overview of the nitrogen sources across the
Americas and how they vary from one region to another. This paper is an
introductory paper for a series of six following papers that detailed the
nitrogen cycle in different countries or in important sub-regions of these
countries. Among these papers, Schindler et al. discuss N-deposition related
issues in Canada, followed by Austin et al. who present a nitrogen budget for
Argentina, one of the most important regions of cereal production in the
world. Filoso et al. for Brazil, Baisre for Cuba and Ortiz for Puerto Rico
synthesize quantitative nitrogen assessments for these whole countries, while
Borbor et al. restrict their analyses for the most developed watershed in
Equador. After these country-scale assessments, Howarth et al. and Scavia
& Bricker illustrate aspects of the nitrogen cycle in important regions of the
USA. Howarth et al. illustrate how climate and human activity interact to
regulatethenitrogenexportfromthemajor16watershedsoftheNortheastern
USAregion,oneofthemostpollutedregionsofthecountry.Scavia&Bricker
present a comprehensive approach to problems that the coastal regions of the
USA are facing due to the large amount of nitrogen that these key areas
receive. The last three papers in the issue are mostly a product of the first
2
workshop held in Ubatuba and deal more with nitrogen as a key element in
natural systems. Bustamante et al. present nitrogen as one of the most
important limiting element in savanna ecosystems throughout the world.
Huszar et al. analyze nitrogen limitation in tropical lakes in comparison to
temperate lakes. Finally, Ometto et al. present a detailed description of the
variability of nitrogen and carbon stable isotopes in tropical forests of the
Amazon region. We believe this volume represents a significant advancement
inourabilitytounderstandnaturalprocessesandhumanperturbationsofthe
nitrogen cycle in both temperate and tropical systems, as well as to recognize
several major differences in nitrogen cycling across several countries and
regions of the Americas.
We are in debt with the many institutions and people who helped us to
organize our workshops and prepare the manuscripts. Elvira Cuevas and
MercedesBustamanteandtheirstaffswerewonderfulhostessesinSanJuanand
Brası´lia, respectively. The Ubatuba workshop had financial support from the
Fundac¸a˜o de Amparo a` Pesquisa do Estado de Sa˜o Paulo (FAPESP) and the
EssoBrasileiradePetro´leocompany.TheSanJuanworkshopwassupportedby
theInterAmericanInstituteforGlobalChanges(IAI)andbytheUniversityof
PuertoRicothroughagrantfromtheUSNationalScienceFoundationtoCrest
(Center for Applied Tropical Ecology and Conservation). The Brası´lia work-
shop was mainly supported by the Conselho Nacional de Desenvolvimento
ePesquisas(CNPq),throughitsPro-Sulprogram,andalsobytheIAIandthe
University of Brası´lia. We also thank Suzanne Mekking, the publisher of
Biogeochemistry, forher flexibility and support inpreparing this issue.
Luiz A. Martinelli
CENA, Laboratory of Isotope Ecology
University of Sa˜o Paulo
Piracicaba, SP, Brazil
e-mail: [email protected]
Robert W. Howarth
Department of Ecology Evolutionary Biology
Cornell University
Ithaca, USA
Biogeochemistry(2006)79:3–24 (cid:2)Springer2006
DOI10.1007/s10533-006-9000-3
Sources of reactive nitrogen affecting ecosystems
in Latin America and the Caribbean: current trends
and future perspectives
LUIZ A. MARTINELLI1,*, ROBERT W. HOWARTH2,
ELVIRA CUEVAS3, SOLANGE FILOSO2, AMY T. AUSTIN4,
LORETA DONOSO5, VERA HUSZAR6, DENNIS KEENEY7,8,
LUCIENE L. LARA1, CARLOS LLERENA9, GEORGE MCISSAC10,
ERNESTO MEDINA11, JORGE ORTIZ-ZAYAS12,
DONALD SCAVIA13, DAVID W. SCHINDLER14, DORIS SOTO15
and ALAN TOWNSEND16
1CENA,Av.Centena´rio303,13416-000,Piracicaba,SP,Brazil;2Ecology&EnvironmentalBiology
Department,CornellUniversity,E311CorsonHall,Cornell,Ithaca,NY14853,USA;3Departmentof
Biology,CollegeofNaturalSciences,UniversityofPuertoRico,POBox23360SanJuan,PuertoRico
00931-3360;4FacultyofAgronomy,UniversityofBuenosAiresandIFEVA-CONICET,AvenidaSan
Martı´n 4453, C1417DSE, Buenos Aires, Argentina; 5Instituto Venezuelano de Investigaciones
Cientı´ficas – IVIC, Centro de Ecologı´a, IVIC, Aptdo. 21827, Caracas 1020-A, Venezuela;
6Departamento de Botaˆnica, Universidade Federal do Rio de Janeiro, Museo Nacional, Quinta da
BoaVistas/n,Sa˜oCristo´va˜o–RiodeJaneiro,RJ20940040,Brasil;7AgricultureandBiosystems
Engineering,IowaStateUniversity,3402EisenhowerAve.,Ames,Iowa50010,USA;8Institutefor
Agriculture and Trade Policy, Minneapolis, Minnesota, USA9Universidad Nacional Agraria La
Molina,Apartado456,Lima,Peru;10DepartmentofNaturalResourcesandEnvironmentalSciences,
UniversityofIllinoisatUrbanaChampaign,w-503TurnerHall,1102SouthGoodwinAvenue,Urbana,
IL61801,USA;11InstitutoVenezolanodeInvestigacionesCientı´ficas,LaboratoryPlantPhysiological
Ecology, Centro de Ecologı´a, IVIC, Aptdo. 21827, Caracas, 1020-A, Venezuela; 12Institute for
TropicalEcosystemsStudies,UniversityofPuertoRico,POBox23341SanJuan,PuertoRico00931-
3341;13SchoolofNaturalResourcesandEnvironment,UniversityofMichigan,G520Dana1115,Ann
Arbor,MI,48109,USA;14EcologyDepartment,UniversityofAlberta,Z811,BiologicalSciences
Bldg.,114St–89Ave,Edmonton,Alberta,T6G2E1,Canada;15UniversidadAustraldeChile,Casilla
1327,PuertoMontt,Chile;16INSTAARandEPO-Biology,UniversityofColorado,156030thSt.,
Boulder,CO80309,USA;*Authorforcorrespondence(e-mail:[email protected];phone:+55-
19-3429-4074;fax:[phone])
Keywords: Biomassburning,Caribbean,LatinAmerica,Nitrogen,Reactiveagriculture,Urban-
ization
Abstract. While the amount of reactive nitrogen circulating at the global level has increased
markedlyinthelastcentury,theeffectsofthisincreasearelargelyseenattheregionalleveldueto
interactingecologicalandsocio-economicfactors.Incontrastwithmostotherregionsoftheworld,
LatinAmericaandtheCaribbean(LA-Ca)standoutduetothefactthatthemajorinputofreactive
nitrogen(Nr)stilloccursnaturallyviabiologicalnitrogenfixation(BNF)innaturalecosystemsas
opposedtoanthropogenicinputsofsyntheticfertilizer,fossilfuelcombustionandcroppingwith
leguminousspecies.Largelyduetoeconomicreasons,theconsumptionoffertilizerNintheLA-Ca
regionisstilllowincomparisonwiththeaverageconsumptionoftheworld.However,thefertilizer
Nconsumptionisincreasingatamuchfasterratethanthatindevelopedregionsoftheworld,like
4
USAandCanada.TheNrproductionthroughBNFincultivatedplantsthatfixnitrogen(C-BNF)is
5timeslowerthanthatoccurringnaturallyinLatinAmerica,butisstillequivalentto16%ofthe
worldC-BNF.Thecultivationofnitrogen-fixingcropspeciesintheLA-Caregionisalsoincreasing,
almostentirelyduetotheexpansionofsoybeanfieldsinthecentralandnorthernregionsofBrazil
andthePamparegionofArgentina.Otheranthropogenicactivitiesintheregionthatcontributeto
an increase in the circulation of reactive nitrogen include the impact of biomass burning and
urbanization.Inthelastdecade,anaverageof47,000km2peryearofforestswasburnedintheLA-
Ca region. The environmental impact of urban centers in the LA-Ca region has become very
important,sinceanintenseurbanizationprocessisoccurringinthisregion,atanintensitythatfar
exceedsurbandevelopmentinthenorthernhemisphere.Theconsequencesofincreasedurbanization
includeincreasedemissionsofNO totheatmosphereduetothefossilfuelcombustion,andthelack
x
ofsewagetreatmentfacilitiesinmostcitiesoftheLA-Caresultinalargevolumeofuntreatedsewage
dischargedintosurfacewaters,creatingseriousenvironmentalproblems.Thecombinationofrapid
urbanizationandagriculturalintensificationinthisregionsuggestthatconcerniswarrantedforthe
potentialforincreaseinthecirculationofreactivenitrogenintheverynearfuture.Atthesametime,
theopportunitystillexiststomitigatesomeoftheconsequencesofhumanimpactonthenitrogen
cycleinaregionthatstillmaintainsalargefractionofitsnaturalecosystemsintact.
Introduction
The concentration of reactive nitrogen (Nr) on the Earth has dramatically
increasedinthelastcenturyduemainlytotheproductionofsyntheticnitrogen
fertilizer through the Haber–Bosch process, fossil fuel combustion, and the
cultivation of plants that associate with bacteria that fix atmospheric N (Ho-
warthet al.2002;Gallowayet al.2004).Ithasbeenestimatedthatin1860the
productionofanthropogenicNrwas15 TgN yr)1,andthatbytheearly1990’s
it increased by almost 10 times to approximately 140 Tg N yr)1 (Galloway
et al. 2004). Although these estimates are important in providing a global
pictureofthealterationoftheNcyclebyhumanactivity,theydonotallowus
to propose actions that would help mitigate the deleterious effects of N in the
environment and for human health occurring at regional or local scale. Much
moredetailedspatialinformationontheproductionandfateofNrisneededto
propose such actions.
Galloway et al. (2004) investigated geopolitical N budgets and showed that
Latin America stands out as the region with highest inputs of Nr by naturally
occurring biological nitrogen fixation (BNF) – an amount equivalent to 25%
oftheworld’sNrcreatedinterrestrialecosystems.TheNrproductionthrough
BNF in cultivated plants that fix nitrogen (C-BNF) in 1995 was 5 times lower
thanthatoccurringnaturallyinLatinAmerica,butwasstillequivalentto16%
of the world C-BNF. On the other hand, Latin America was responsible in
1995foronly6%oftheworld’sNrcreatedthroughfossilfuelcombustion,and
for only 4% of the Nr originated from synthetic N fertilizer (Galloway et al.
2004).
In this paper, we provide an evaluation of the origin of reactive nitrogen in
Latin America, and compare it to other areas of the world. The contrasts
between impacts at the global and regional scale may help to suggest ways in
5
whichwecanmitigatethedeleteriouseffectsofhumanimpactontheNcyclein
thecomingdecades.Assessingnotonlythecurrentstateofhumanimpact,but
the velocity of change in this region highlights the importance of focusing on
regionswherethepotentialhumanimpactinthecomingdecadeswillbelarge,
and where preventative steps could be taken to minimize the negative impacts
of human-induced changes in nitrogen cycling.
The geography and socio-economic aspects of the Latin America
and the Caribbean (LA-Ca) regions
Geography
Becausestatisticsaregenerallycategorizedbycountryorpoliticalunitinmost
data bases, we define Latin America and the Caribbean, including their
countries and territories, as shown in Table 1 (http://www.cia.gov/cia/publi-
cations/factbook/geos/cj.html).
The most typical definition of Latin America is the one that considers the
countries of South America, Central America, the Caribbean, and southern
North America that speak a Romance language, including Spanish, Portu-
guese, and French (Table 1). The Caribbean is defined as a group of islands
locatedintheCaribbeanSea,organizedin25distinctpoliticalunits,including
statesandterritories(Table 1).Geographicaloreconomicalandsocialindexes
are available for most independent countries and, in some cases, for political
units as well. For example, Puerto Rico is a commonwealth of the United
States (US), and as a result, its data are sometimes aggregated to that the US
statistics, while in other cases, they are reported as an independent political
unit.AsmostproductionanduseofNrislinked toeconomicindicators,such
as use of fossil fuel, fertilizer use, and cultivation of commercially important
plants that have N-fixing symbioses, it is useful to provide Latin American
economic and social indicators for context.
Social and economical indicators
The Gross Domestic Product (GDP) index (Human Development Report
2003), (defined as the total value of goods and services produced by a nation
and expressed on a per capita basis) varied from 0.48 to 0.83 for LA-Ca
countries in 2003 (Figure 1).
Approximately 40% of the LA-Ca countries had a GDP index higher than
theoverallaveragefordevelopingcountries(0.70).BoliviaandNicaraguahad
indexesonlyslightlyhigherthan0.5,whileHaitiwastheonlycountrywithan
indexlowerthantheaverageoftheleastdevelopingcountries(0.5).(Figure 1).
The highest indexes were observed in the Bahamas and Barbados. However,
bothvaluesweresignificantlylowerthantheaverageoftherichestcountriesof