Ecological response to altered rainfall differs across the Neotropics

TRZCINSKI, M. KURTIS; MERCADO, DIMARIS ACOSTA; ROMERO, GUSTAVO Q.; DÉZERALD, OLIVIER; PICCOLI, GUSTAVO C. O.; LEAL, JULIANA S.; FREIRE, RODRIGO; OMENA, PAULA M.; CÉRÉGHINO, RÉGIS; MARINO, NICHOLAS A. C.; CORBARA, BRUNO; BARBERIS, IGNACIO M.; ATWOOD, TRISHA B.; CARRIAS, JEAN?FRANÇOIS; ANTIQUEIRA, PABLO A. P.; AMUNDRUD, SARAH L.; SRIVASTAVA, DIANE S.; MACDONALD, A. ANDREW M.; LEROY, CÉLINE; FARJALLA, VINICIUS F.; HAMMILL, EDD; OSPINA-BAUTISTA, FABIOLA; MONTERO, GUILLERMO; REALPE, EMILIO; CAMPOS, ALICE B. A.

ECOLOGY

ECOLOGICAL SOC AMER

Lugar: Washington; Año: 2020 vol. 101 p. 1 - 15

0012-9658

Abstract. There is growing recognition thatecosystems may be more impacted by infrequent extreme climatic events than bychanges in mean climatic conditions. This has led to calls for experiments thatexplore the sensitivity of ecosystems over broad ranges of climatic parameterspace. However, because such response surface experiments have so far beenlimited in geographic and biological scope, it is not clear if differencesbetween studies reflect geographic location or the ecosystem componentconsidered. In this study, we manipulated rainfall entering tank bromeliads inseven sites across the Neotropics, and characterized the response of theaquatic ecosystem in terms of invertebrate functional composition, biological stocks(total invertebrate biomass, bacterial density) and ecosystem fluxes(decomposition, carbon  nitrogen). Ofthese response types, invertebrate functional composition was the mostsensitive, even though, in some sites, the species pool had a high proportionof drought-tolerant families. Total invertebrate biomass was universallyinsensitive to rainfall change because of statistical averaging of divergentresponses between functional groups. The response of invertebrate functionalcomposition to rain differed between geographical locations because (1) the effectof rainfall on bromeliad hydrology differed between sites, and invertebratesdirectly experience hydrology not rainfall and (2) the taxonomic composition ofsome functional groups differed between sites, and families differed in theirresponse to bromeliad hydrology. These findings suggest that it will bedifficult to establish thresholds of ?safe ecosystem functioning? when ecosystem components differ in their sensitivity to climaticvariables, and such thresholds may not be broadly applicable over geographicspace. In particular, ecological forecast horizons for climate change may bespatially restricted in systems where habitat properties mediate climaticimpacts, and those, like the tropics, with high spatial turnover in speciescomposition.