The role of timing, duration, and frequency of inundation in controlling leaf litter decomposition in a river-floodplain ecosystem (Tagliamento, northeastern Italy)
Tóm tắt
Despite growing recognition of the importance of a natural flow regime in river-floodplain systems, researchers struggle to quantify ecosystem responses to altered hydrological regimes. How do frequency, timing, and duration of inundation affect fundamental ecosystem processes such as leaf litter decomposition? Along the semi-natural Tagliamento River corridor, located in northeastern Italy, we employed in situ experiments to separate effects of different inundation components on breakdown rates of black poplar (Populus nigra). We used a litter-bag method with two different mesh sizes to investigate how fungi and macroinvertebrates influence leaf breakdown rates. Ten treatments, each representing a specific combination of duration and frequency of inundation, were deployed in two seasons (summer, winter) to mimic complex inundation patterns. After 30 days of exposure, mean percentage of remaining leaf litter (ash free dry mass) ranged between 51% (permanent wet) and 88% (permanent dry). Leaf breakdown was significantly faster in winter than in summer. Duration of inundation was the main inundation component that controlled leaf breakdown rates. Leaf-shredding macroinvertebrates played only a role in the permanent wet treatment. Fungal parameters explained the faster leaf breakdown in winter. Our study suggests that modifications of the inundation regime will directly modify established decomposition processes. Factors reducing duration of inundation will decelerate leaf breakdown rates, whereas a decrease in flow variation will reduce leaf breakdown heterogeneity.
Tài liệu tham khảo
Anderson DC, Nelson SM, Binkley D (2003) Flood flows, leaf breakdown, and plant-available nitrogen in a dryland river floodplain. Wetlands 23:180–189
Arscott DB, Tockner K, Ward JV (2002) Geomorphic dynamics along a braided-river corridor in the Alps (Fiume Tagliamento, Italy). Ecosystems 5:803–814
Austin AT (2002) Differential effects of precipitation on production and decomposition along a rainfall gradient in Hawaii. Ecology 83:328–338
Baldy V, Gessner MO, Chauvet E (1995) Bacteria, fungi and the breakdown of leaf litter in a large river. Oikos 74:93–102
Battle JM, Golladay SW (2001) Hydroperiod influence on breakdown of leaf litter in cypress-gum wetlands. Am Midl Nat 146:128–145
Boulton AJ (1991) Eucalypt leaf decomposition in an intermittent stream in south-eastern Australia. Hydrobiologia 211:123–136
Boulton AJ, Boon PI (1991) A review of methodology used to measure leaf litter decomposition in lotic environments: time to turn over an old leaf? Aust J Mar Fresh Res 42:1–43
Brinson MM (1977) Decomposition and nutrient exchange of litter in an alluvial swamp forest. Ecology 58:601–609
Bunn SE, Arthington AH (2002) Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environ Manage 30:492–507
Busch DE (1995) Mechanisms associated with decline of woody species in riparian ecosystems of the southwestern US. Ecol Monogr 65:347–370
Carreiro MM, Koske RE (1992) Effect of temperature on decomposition and development of microfungal communities in leaf litter microcosms. Can J Bot 70:2177–2183
Chauvet E (1988) Influence of the environment on willow leaf litter decomposition in the alluvial corridor of the Garonne River. Arch Hydrobiol 112:371–386
Chergui H, Pattee E (1988) The impact of benthic invertebrates on the breakdown of poplar leaves in the network of a large European river. Arch Hydrobiol 113:15–25
Cleveland C, Neff JC, Townsend AR, Hood E (2004) Composition, dynamics, and fate of leached dissolved organic matter in terrestrial ecosystems: results from a decomposition experiment. Ecosystems 7:275–285
Cuffney TF, Wallace JB (1987) Leaf litter processing in coastal plain streams and floodplains of southeastern Georgia, USA. Arch Hydrobiol Suppl 76:1–24
Dangles O, Malmqvist B (2004) Species richness-decomposition relationships depend on species dominance. Ecol Lett 7:395–402
Day FP (1983) Effects of flooding on leaf litter decomposition in microcosms. Oecologia 56:180–184
Fierer N, Schimel JP, Holden PA (2003) Influence of drying-rewetting frequency on soil bacterial community structure. Microbial Ecol 45:63–71
Gessner MO, Schmitt AL (1996) Use of solid-phase extraction to determine ergosterol concentrations in plant tissue colonized by fungi. Appl Environ Microbiol 62:415–419
Glazebrook HS, Robertson AI (1999) The effect of flooding and flood timing on leaf litter breakdown rates and nutrient dynamics in a river red gum (Eucalyptus camaldulensis) forest. Aust J Ecol 24:625–635
Graça MAS, Ferreira RCF, Coimbra CN (2001) Litter processing along a stream gradient: the role of invertebrates and decomposers. J N Am Benthol Soc 20:408–420
Gurnell AM, Tockner K, Edwards P, Petts G (2005) Effects of deposited wood on biocomplexity of river corridors. Front Ecol Environ 3:377–382
Hagvar S (1988) Decomposition studies in an easily constructed microcosm: effects of microarthropods and varying soil pH. Pedobiologia 31:293–303
Harner MJ, Stanford JA (2003) Differences in cottonwood growth between a losing and a gaining reach of an alluvial floodplain. Ecology 84:1453–1458
Hart DD, Finelli CM (1999) Physical-biological coupling in streams: the pervasive effects of flow on benthic organisms. Annu Rev Ecol Syst 30:363–395
Heffernan JB, Sponseller RA (2004) Nutrient mobilization and processing in Sonoran desert riparian soils following artificial re-wetting. Biogeochemistry 70:117–134
Herbst G, Reice SR (1982) Comparative leaf litter decomposition in temporary and permanent streams in semi-arid regions of Israel. J Arid Environ 5:305–318
Hession WC, Johnson TE, Charles DF, Hart DD, Horwitz RJ, Kreeger DA, Pizzuto JE, Velinsky DJ, Newbold JD, Gianfrani C, Clason T, Compton AM, Coulter N, Fuselier L, Marshall BD, Reed J (2000) Ecological benefits of riparian reforestation in urban watersheds: study design and preliminary results. Environ Monit Assess 63:211–222
Hieber M, Gessner MO (2002) Contribution of stream detritivores, fungi, and bacteria to leaf breakdown based on biomass estimates. Ecology 83:1026–1038
Hutchens JJ Jr, Wallace BJ (2002) Ecosystem linkages between southern Appalachian headwater streams and their banks: leaf litter breakdown and invertebrate assemblages. Ecosystems 5:80–91
Irons JG, Oswood MW, Stout RJ, Pringle CM (1994) Latitudinal patterns in leaf litter breakdown: is temperature really important? Freshw Biol 32:401–411
Junk WJ, Bayley PB, Sparks RE (1989) The flood pulse concept in river-floodplain systems. Can Spec Publ Fish Aquat Sci 106:110–127
Kaiser E, Arscott DB, Tockner K, Sulzberger B (2004) Sources and distribution of organic carbon and nitrogen in the Tagliamento River, Italy. Aquat Sci 66:103–116
Karrenberg S, Kollmann J, Edwards PJ, Gurnell AM, Petts GE (2003) Patterns in woody vegetation along the active zone of a near-natural Alpine river. Basic Appl Ecol 4:157–166
Kuehn KA, Steiner D, Gessner MO (2004) Diel mineralization patterns of standing-dead plant litter: implications for CO2 flux from wetlands. Ecology 85:2504–2518
Lockaby BG, Murphy AL, Somers GL (1996) Hydroperiod influences on nutrient dynamics in decomposing litter of a floodplain forest. Soil Sci Soc Am J 60:1267–1272
Menéndez M, Hernández O, Comín FA (2003) Seasonal comparisons of leaf processing rates in two Mediterranean rivers with different nutrient availability. Hydrobiologia 495:159–169
Mitsch WJ, Gosselink JG (1993) Wetlands, 2nd edn. Van Nostrand Reinhold, New York
Molles MC, Crawford CS, Ellis LM (1995) Effects of an experimental flood on litter dynamics in the middle Rio Grande riparian ecosystem. Regul River 11:275–281
Paetzold A, Schubert C, Tockner K (2005) Aquatic-terrestrial linkages along a braided-river: Riparian arthropods feeding on aquatic insects. Ecosystems (in press)
Pereira AP, Graça MAS, Molles M (1998) Leaf litter decomposition in relation to litter physico-chemical properties, fungal biomass, arthropod colonization, and geographical origin of plant species. Pedobiologia 42:316–327
Poff NL, Allan JD, Bain MB, Karr JR, Prestegaard KL, Richter BD, Sparks RE, Stromberg JC (1997) The natural flow regime: a paradigm for conservation and restoration. BioScience 47:769–784
Poff NL, Hart DD (2002) How dams vary and why it matters for the emerging science of dam removal. BioScience 52:659–668
Robertson AI, Bunn SE, Boon PI, Walker KF (1999) Sources, sinks and transformations of organic carbon in Australian floodplain rivers. Mar Freshw Res 50:813–829
Robertson AI, Bacon P, Heagney G (2001) The responses of floodplain primary production to flood frequency and timing. J Appl Ecol 38:126–136
Robinson CT, Gessner MO (2000) Nutrient addition accelerates leaf breakdown in an alpine springbrook. Oecologia 122:258–263
Richter BD, Baumgartner JV, Wigington R, Braun DP (1997) How much water does a river need? Freshw Biol 37:231–249
Ryan TP (1997) Modern regression methods. Wiley, New York, pp 145–147
Ryder DS, Horwitz P (1975) Seasonal water regimes and leaf litter processing in a wetland on the Swan Coastal Plain, Western Australia. Mar Freshw Res 46:1077–1084
Shaw MR, Harte J (2001) Control of litter decomposition in a subalpine meadow-sagebrush steppe ecotone under climate change. Ecol Appl 11:1206–1223
Shure DJ, Gottschalk MR, Parsons KA (1986) Litter decomposition processes in a floodplain forest. Am Midl Nat 115:314–327
Tachet H, Richoux P, Bournaud M, Usseglio-Polatera P (2000) Invertébrés d’eau douce: systématique, biologie, écologie. CNRS Éditions, Paris
Tiegs SD, Pohl MM (2005) Planform channel dynamics of the lower Colorado River: 1976–2000. Geomorphology 69:14–27
Tiegs SD, O’Leary JF, Pohl MM, Munill CL (2005) Flood disturbance and riparian species diversity on the Colorado River Delta. Biodivers Conserv 14:1175–1194
Tockner K, Malard F, Ward JV (2000) An extension of the flood pulse concept. Hydrol Process 14:2861–2883
Tockner K, Ward JV, Arscott DB, Edwards PJ, Kollmann J, Gurnell AM, Petts GE, Maiolini B (2003) The Tagliamento River: a model ecosystem of European importance. Aquat Sci 65:239–253
Van der Nat D (2002) Ecosystem processes in the dynamic Tagliamento river (NE-Italy). Dissertation, Swiss Federal Institute of Technology
Van der Nat D, Schmidt AP, Tockner K, Edwards PJ, Ward JV (2002) Inundation dynamics in braided floodplains: Tagliamento River, Northeast Italy. Ecosystems 5:636–647
Wallace JB, Eggert SL, Meyer JL, Webster JR (1997) Multiple trophic levels for a forested stream linked to terrestrial litter inputs. Science 277:102–104
Ward JV, Tockner K, Edwards PJ, Kollmann J, Bretschko G, Gurnell AM, Petts GE, Rossaro B (1999) A reference river system for the Alps: the ‘Fiume Tagliamento’. Regul River 15:63–75
Webster JR, Benfield EF (1986) Vascular plant breakdown in freshwater ecosystems. Ann Rev Ecol Syst 17:567–594
Webster JR, Benfield EF, Ehrmann TP, Schaeffer MA, Tank JL, Hutchens JJ, D’Angelo DJ (1999) What happens to allochthonous material that falls into streams? A synthesis of new and published information from Coweeta. Freshwater Biol 41:687–705
Wieder RK, Lang GE (1982) A critique of the analytical methods used in examining decomposition data obtained from litter bags. Ecology 63:1636–1642