QBRy a Method for Assessing the Ecological Quality of Riparian Forests

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Ecological Indicators 20 (2012) 324–331

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Ecological Indicators

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A method for assessing the ecological quality of riparian forests in subtropicalAndean streams: QBRy index

Martín G. Sirombra a, Leticia M. Mesa b,∗

a Cátedra EcologíaGeneral, Instituto de LimnologíadelNoroesteArgentino (ILINOA), Facultadde Ciencias Naturales e InstitutoMiguelLillo, UniversidadNacionalde Tucumán,Miguel

Lillo 205, 4000 San Miguel de Tucumán, Tucumán, Argentinab Instituto Nacional de Limnología, CiudadUniversitaria, Pje. El Pozo, 3000 Santa Fe, Argentina

a r t i c l e i n f o

Article history:

Received 8 August 2011Received in revised form 15 February 2012Accepted 20 February 2012

Keywords:

Anthropogenic impactsQBRy indexRiparian qualityYungas forest

a b s t r a c t

A modified QBR index adapted to examine the riparian quality of streams included in the Yungas biomeis presented. The index, named QBRy, included modifications of the original index in three of the foursections in order to be useful for the studied region. The assessment of QBRy included trials in threesubtropical sub-basins of Tucumán province (Argentina). Thirty-seven sampling sites were assessed. Thecomposition of riparian forest varied in relation to a geographical pattern, and this was related with theclimatic differences existing within the same ecoregion. The quality of riparian vegetation was poor nearpopulation centers and in sites impacted by livestock, while good quality conditions were related withareas adjacent to a protected region and in physiographical inaccessible zones. The introduction of exoticspecies represents a real problem to the integrity of Yungas riparian vegetation. The protection of thefew well preserved zones and the necessity of restoration of highly altered ones becomes an essentialpriority for biodiversity conservation.

© 2012 Elsevier Ltd. All rights reserved.

1. Introduction

Riparian vegetation structure, composition and dynamics havereceived growing attention in the past decade ( Jungwith et al.,2002; Richardson et al., 2007; Yang et al., 2011). The ripar-ian zone is defined as the transitional area between a river orstream and the adjacent terrestrial upland ecosystem, includ-ing both the stream channel itself and the surrounding landthat is influenced by fluctuating water levels (Malanson, 1993).It can support a high biodiversity; protects the main chan-nel from temporal changes, buffers large disturbances, regulatesthe temperature of streams, filters and retains nutrients andprovides habitat, refuge and food for wildlife (Naiman et al.,1993; Stanford and Ward, 1993; Naiman and Décamps, 1997).Although all services provided by these ecosystems are criti-

cal for ecological functions, the riparian forests are among themost threatened ecosystems in the world (Tockner and Stanford,2002).

YungasisanAndeanbiomethatextendsinVenezuela,Colombia,Bolivia and the northwestern region of Argentina. In Argentina,Yungas ranges from the frontier of Bolivia (23◦) to the north of

∗ Corresponding author. Tel.: +54 342 4511645/48x106;fax: +54 342 4511645x111.

E-mail addresses: [email protected] (M.G. Sirombra), [email protected](L.M. Mesa).

Catamarca (29◦), with an area of 52,000km2. Minimum and max-imum altitudes varies between 400 and 3000m.a.s.l., respectively.This biome, which includes the headwaters of the most importantbasins, plays an important role in the regulation of the hydraulic of streams that goes through the American continent, and enhancesa high biodiversity of species with a high number of endemism(Brown, 1986; Brown et al., 2002).

Yungas riparian forests have been subjected to intensive land-use scenarios. Agricultural transformations, road construction,gravel extractions, deforestation, overgrazing and the introductionof exotic species are some impacts that affect biotic communitiesand individual species (Grau and Aragón, 2000; Brown et al., 2006;Balducci et al., 2009).

Being under increasing threats and in order to conserve andmanage the remaining riparian forests, it is useful to describe the

riparian zone in a systematic and, if possible, low time-consumingway.

The QBR index (“qualitat del bosc de ribera”) is a simple methodto evaluate riparian habitat quality. It was developed to be usedin Mediterranean streams of Spain (Munné et al., 1998; Prat et al.,1999; Suárezet al., 2002;Munné et al., 2003) andapplied in severalregions of theworld with satisfactoryresults (Ocampo-Duque et al.,2007; Palma et al., 2009; Kazoglou et al., 2010). Some changes havebeenintroducedbyseveralauthorsinordertoadaptittoothergeo-graphical areas (Colwell, 2007; Acosta et al., 2009; Kutschker et al.,2009), although the basic structure and the assessment procedurehave not significantly changed.

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M.G. Sirombra, L.M. Mesa / Ecological Indicators 20 (2012) 324–331 325

Fig. 1. Map of thethreestudied sub-basins showing thesampled sites, their localizationin Tucumán province and thenearest urban centers. In shading withinTucumán isthe localization of Yungas biome. Theposition of theprotected area in thenorthside of San JavierHill is also shown.

This paper describes the adaptation of the QBR index in order toassess the riparian quality of Yungas streams. The adapted index,named QBRy, was applied in three sub-basins of the northwest-ern Argentina. We also explored the spatial distribution of riparianspecies and its relationship with some variables.

We tested the hypothesis that: (1) riparian composition variesaccording to a geographical pattern of distribution, and (2) val-ues of QBRy are higher in sites of higher altitude due the loweranthropogenic impacts in these regions.

2. Materials and methods

2.1. Study area

The adaptation of the QBR index included trials in subtropicalstreams of the northwestern Argentina including within Yungasbiome. Thirty-seven sites in three sub-basins were studied: 8 inMarapa River, 11 in Lules River and 18 in the eastern side of theSan Javier Hill. These sub-basins were selected in order to the dis-tinct environmental conditions that include. Lules River sub-basinis located in the central-west of Tucumán province, with an area of 787km2. The maximum altitude is around 4488m.a.s.l., decreasingtoward the piedmont (408m.a.s.l) (Fig. 1). San Javier Hill is situ-ated in the eastern of this sub-basin, with altitudes between 600and1900m.a.s.l. On the eastern of San Javier Hill, several loworderstreams infiltrate to reach the flat area. This sub-basin includes aprotected area in the north, San Javier Hill Park (140km2), man-aged by the National University of Tucumán (Fig. 1). Marapa River

sub-basinislocatedinthesouthwesternofTucumánprovince,with

several important streams such as Chavarría, Las Moras, El Chorroand Singuil draining into Escaba reservoir (Fig. 1).The studied region is subject to the monsoon climate, with an

average annual precipitation of 1000mm. Within Yungas, climaticcondition varies strongly in short distances (Brown et al., 2002;Bianchi, 2006). Altitude,the exposure of mountain ranges to humidsoutheastern winds and the presence of a particular geological fea-ture (Conception bay) significantly influence the distribution andintensity of precipitation. The region of maximum precipitationranges from Santa Ana Hill to Potrero de las Tablas, including LulesRiver and the eastern side of San Javier Hill sub-basins (2000 mmannually). Marapa River, located in the southern of Santa Ana Hill,presents a drier climate, with an annual precipitation between 800and 1000mm (Bianchi, 2006).

2.2. Riparian vegetation sampling

Each studied site wascentered on the stream-bed and extended50m in length following the stream channel. The width was vari-able, extending through the riparian forest to the edge of thefloodplain.Floodplain width wasdelimitedtakingintoaccountsev-eral characteristics such as bank topography, position of terracesor dikes, presence of piles of debris left by previous flooding andindicator species. In areas with a narrow riparian corridor, for-est edge was considered. Individual trees from 30cm perimeterat breast height (PAP) were considered to limit the riparian area.Presence/absence data of trees, shrubs and woody climbers wererecorded. We followed Zuloaga and Morrone (2011) f or taxonomic

identification of the riparian species.



326 M.G. Sirombra, L.M. Mesa / Ecological Indicators 20 (2012) 324–331

2.3. QBRy index

Changes were made in three of the four sections of the QBR inorder to be applied to Yungas streams. The first section of the orig-inal index, total riparian cover, had remained unchanged. In thesecond component of the QBR, cover structure, the community of helophytes was replaced by a more representative community of mountain streams such as woody climbers. The main differencebetween the QBRy and the original QBR was related with the thirdcomponent. This was simplified in the QBRy: cover quality wasestimated taking into account the percentage of native and exoticspecies independent of their number and the geomorphologic typeof the studied site. Finally, in the forth component of the originalindex, channel alteration, the distinction of the impact on one ortwo terraces and margins was considered in order to facilitate themonitoring of the studied area. New sections related with com-mon anthropogenic impacts in the Yungas biome were included asfactors that decrease the score of this section.

2.4. Statistical analyses

A non-metric multidimensional scaling (NMS) with Sorensen’s

distance was used to explore the patterns in the presence–absenceof riparian vegetation data (PC-ORD 4.27, McCune and Mefford,1999). One hundred iterations were carried outfrom randomstart-ing co-ordinates with a step length of 0.2 (the default rate of movement toward minimum stress).

Spearman correlation analysis was used to examine the rela-tion between the values of the QBRy and altitude of each site, andthe relation between the axes of NMS and several selected vari-ables (values of QBRy, altitude, mean bankfull height, richness andnumber of exotic and native species).

3. Results

3.1. QBRy index

A total of seventy-seven riparian species were found (AppendixA). Thirty-five were present in Marapasub-basin, fiveof these wereexotic; Lules sub-basin included forty-eight species (eight exotic),whereas sixty species were found in streams of the eastern side of San Javier Hill (twelve exotic).

The field sheet of QBRy index is shown inAppendix B.The geographic position,altitude, mean bankfull heightand val-

uesofQBRyrelativetoeachsiteandsub-basinareshownin Table1.The values of QBRy ranged from 15 to 100 (Table 1). Most sitesrelative to Marapa and Lules sub-basins (>45%) had good quality(QBRy=75–90). In addition, 30% of sites of Lules and San Javier Hillsub-basins had extreme degradation (QBRy< 25) (Fig. 2).

In Marapa sub-basin, sites 1 and 7 showed the highest and

lowest values of QBRy, respectively (95 and 45); sites 9, 12 and13 exhibited the lowest values of this index in the Lules basin(QBRy≤25), whereas the riparian habitat of site 15 was in naturalcondition(Table1). IntheeasternsideofSanJavierHill,theriparianzones of sites 26, 27, 34, 35 and 36 exhibited extreme degradation(QBRy≤25), whereas in 1, 15, 28, 29 and 30 the riparian habitatwere in natural condition (QBRy≥95) (Table 1).

The values of the sections total riparian cover and alterationsin the riparian zone were higher in Marapa sub-basin than inthe other two sub-basins (Kruskal–Wallis test, H =7.24, P <0.05;H =11.9, P < 0.001, respectively, Fig.4) determining the better ripar-ian conditions of this basin. Some sites of Lules sub-basin showedthe lower values of total riparian cover, cover structure and coverquality, whereas in San Javier Hill, some sites exhibited the lower

values of the section channel alteration (Fig. 4). Anthropogenic

Fig.2. Relative number of sites(in percentage) of eachriparianqualityclass foreachsub-basin.

Fig. 3. Box-plot of values of the QBRy relative to each site for the three studied

sub-basins (mean, median and standard deviation arealso shown).

Fig. 4. Box-plot of values of each section of QBRy relative to each site for the threestudied sub-basins (mean, median and standard deviation arealso shown).

modificationsin the stream channel andfloodplain determined lowvalues of the QBRy in most sites of San Javier Hill sub-catchment(Table 1, Figs. 3 and 4).

Correlation value between altitude and QBRy was positive andsignificant (R=0.40, P = 0.01), indicating the higher quality of ripar-ian vegetation of higher altitude sites (Fig. 5).

3.2. Multivariate analysis

The NMS ordination (stress = 22.8, P =0.01) represented 68%

of the variation in the dataset, with 35% on axis 1 and 33%




Table 1

Geographic position,altitude,mean bankfull height and values of theQBRy relative to each site and sub-basin.

Sub-basin Site Latitude/longitude Altitude (m.a.s.l) Mean bankfull height (m) QBRy

Marapa 1 27◦3759S;65◦4734W 651 0.8 952 27◦3815S;65◦4726W 653 1.3 853 27◦3848S;65◦4713W 633 2.2 754 27◦3848S;65◦4772W 633 4.0 855 27◦4036S;65◦4942W 754 3.0 806 27◦4036S;65◦4941W 779 1.5 90

7 27◦

41

18

S;65◦

47

51

W 657 0.4 458 27◦4120S;65◦4755W 662 0.4 70Lules 9 26◦4626S;65◦2323W 860 2.8 15

10 26◦4728S;65◦ 2356W 830 1.2 7511 26◦5118S;65◦2546W 650 0.9 8512 26◦5123S;65◦2553W 680 1.6 2513 26◦ 5139S;65◦2588W 692 1.7 2514 26◦4824S;65◦2755W 1053 1.3 6015 26◦4816S;65◦2912W 925 0.4 10016 26◦4605S;65◦2852W 957 1.2 9017 26◦4530S;65◦2931W 1070 1.2 9018 26◦4453S;65◦3046W 1105 1.9 9019 26◦4324S;65◦2667W 1127 2.0 50

San Javier Hill 20 26◦432S;65◦1812W 929 3.5 9021 26◦435S;65◦1745W 863 1.3 6522 26◦4315S;65◦1732W 832 0.5 9023 26◦4327S;65◦1724W 761 1.7 4024 26◦4334S;65◦1713W 746 2.8 4025 26◦4343S;65◦1700W 733 3.4 2526 26◦4482S;65◦1649W 688 2.2 4027 26◦4434S;65◦1629W 635 1.6 2528 26◦4327S;65◦1810W 886 1.8 9529 26◦4329S;65◦182W 872 1.9 9530 26◦4330S;65◦1759W 855 1.6 9531 26◦4336S;65◦1743W 814 2.5 7532 26◦4348S;65◦1727W 769 5.0 6033 26◦4352S;65◦1724W 751 2.2 5534 26◦440S;65◦1717W 714 3.9 2535 26◦4411S;65◦172W 697 2.3 2536 26◦4832S;65◦1935W 559 2.5 1537 26◦4722S;65◦1950W 656 1.5 65

Fig.5. Relationship between altitude and valuesof QBRy.Result of correlation anal-ysis and significance value were alsoshowed.

on axis 2 (Fig. 6). Ordination diagram separated sites accordingwith the sub-basin. Myrcianthes cisplatensis, Phyllostylon rham-

noides, Schinus bumelioides and Ruprechtia laxiflora characterizedMarapa sub-basin, Zanthoxilum naranjillo and Duranta serratifo-

lia were associated with Lules, whereas twelve species (Sambucus

peruvianum, Rubus imperiales, Urera baccifera, Persea americana,Lantana camara, Psychotria carthagenensis, Heliocarpus popayanen-sis,Guaduaangustifolia,Eucalyptussp., Tabebuiaavellanedae, ArundodonaxandEriobotrya japonica) characterized streams of the eastern

side of San Javier Hill.

The number of exotic species was positively and significantlyassociated with axis 1, whereas the values of QBRy and altitudewere negatively associated with this axis (Table2). Axis 2 exhibitedanegativerelationshipwithaltitude,richnessandnumberofnativespecies (Table 2).

Fig. 6. Sites ordination of non-metric multidimensional scaling plot based onpresence–absencedata of riparian species. Dotted lineenclosessites relative to each

sub-basin.




Table 2

Results of correlation analysis between variables and axes 1 and 2 of non-metricmultidimensional scaling ordination.

Variables 1 2

QBRy −0.52**−0.12

Altitude (m.a.s.l.) −0.38**−0.56**

Mean bankfull height (m) 0.27 −0.04Richness 0.04 −0.40**

Number of exotic species 0.49** 0.03

Numberof native species −0.08 −0.46**

*P <0.05.** P <0.01

4. Discussion

4.1. Yungas riparian vegetation

Yungas riparian species were the same than those occurringin adjacent areas such as terraces (Sirombra and Mesa, 2010). Ahumidclimate characterizes this biome, determining that water benot restrictive to the establishment of species. This characteristicdiffered from several studies related with arid regions (Suárezet al., 2002; Richardson et al., 2007) delimiting a restricted areaof riparian species different in structure and function from the

adjacent terrestrial zone.Disturbance, climate change and spatial heterogeneity are

important influential factors of the structure and functioning of plant communities, which often are not in compositional equilib-rium (Pickett and White, 1985; Chesson and Huntly, 1997). Theriparian species of the studied area have to deal with the hydrolog-ical disturbance related with the monsoonal climate. Most speciesdo notdepend on a periodof floodedsoil,although some vital func-tions may be related with the aquatic environment (Neiff, 2004).In addition, hydraulic impacts enabled the development of mor-phological adaptations in some species in order to withstandingflooding. During high water period, spates produce abrasion anderosion of thebanks, displacing andkilling most part of theriparianvegetation. Longs and whole trees are displacing downstream,

leading open areas to be colonized during low water period. Therapid dispersion of seeds of alien plants by floods and cattle addedto the high edge:area ratio would determine that exotic vegetationbe the pioneer colonizer of riparian area (Ede and Hunt, 2008).

In accordance with the first hypothesis, ordination analysisdetected a geographical pattern of distribution of riparian species,and this was related with the climatic differences existing withinthe same biome. The southern area of Yungas is drier than those atlower latitude (Bianchi, 2006). Marapa River sub-basin is situatedin this southern dry zone, determining some singularities in thecomposition of riparian species. For example, M. cisplatensis wasrestricted to this sub-basin. This specie is characteristic of thenorthwestern area of the Chaco dry biome, situated betweenTucumán and Catamarca provinces, near to Marapa sub-basin

(Demaio et al., 2002). The climatic similarity of the northwesterndry Chaco forest with the southern area of Yungas would deter-minate that M. cisplatensis be exclusive in Marapa sub-basin. Inaddition, this zone could represent a transitional area betweenthese two ecoregions.

The negative significant relationship between the first axis of the NMS and the total values of QBRy showed the higher anthropicpressure on riparian vegetation of San Javier Hill sub-basin,reflected in a higher numberof exoticspecies. In addition,this rela-tionship showed the sensitive of the modified index to changes inthe structure and composition of species at regional scale.

4.2. QBRy

Modifications of the original QBR were accurate and necessary

in order to evaluate the conservation status of the riparian zone of

Yungasstreams.Changes associatedwith the thirdparagraph of theoriginal QBR were similar to those included in theQBR-And (Acostaet al., 2009). The high richness of riparian trees reported in Andeanstreams (Acosta et al., 2009; Sirombra and Mesa, 2010) added tothe lack of definition of geomorphologic types in Yungas streamsdeterminatedthe necessityof a modification in this section in orderto be applied in the studied area.

According to Fernández et al. (2009)and Kazoglou et al. (2010),sites of QBRy≥95 such as 1, 15, 28, 29 and 30 could be consideredas references due to their natural riparian conditions. The higherstreamquality of thesites 28, 29 and30 would be related with theircloseness with the protected area ‘San Javier Hill Park’. This zoneconstitutes an important reservoir of native riparian vegetation,acting as a buffer in front of increasing anthropogenic threats.

In accordance with the second hypothesis, altitude showed asignificant positive relationshipwith thevalues of QBRy. This resultwasin accordance with other studies (Ibero et al., 1996; CarrascosaGómez andMunné, 2000; Suárezet al., 2002) exposing the increaseof riparian quality in higher altitude sites as a consequence of the higher distance to urban areas and the inaccessibility of theseplaces. In addition, this relation was not strong as we expected,and this was related with the higher value of QBRy in lower sitesof Marapa sub-basin. The distance of these sites to urban areaswould determinate the higher quality of riparian condition in thissub-basin.

4.3. Human disturbances in riparian zones

In recent decades, human factors have played an importantrole, even higher than natural primary succession, in determiningchanges in riparian landscapes (Décamps et al., 1988). The elimi-nation and substitution of native riparian complexes by non-nativeones determinate the simplification of the structural heterogene-ity (e.g. Croonquist andBrooks, 1993; Montalvo and Herrera, 1993;Keller et al., 1993). Exotic vegetation reduces the abundance anddiversity of native species, impacting in long-term on the structureand function of ecosystems (Lowe et al., 2000).

In Yungas riparian forests, cattle has played a definitive role inthe introduction of exotic species (Sirombra and Mesa, 2010). Live-stock, by trampling and browsing, has produced soil compactionand the elimination of native plant regrowth (Sirombra and Mesa,2010). Added to this impact, agriculture expansion, urbanizationand recreation are the main determinants of the proliferation of alien plants (Grau and Aragón, 2000; Grau et al., 2008; Sirombraand Mesa, 2010).

In areas previously impacted by livestock, species character-ized by an endocarp or seed resistant to digestion were abundant.This includes species typical of the Yungas such as Juglans australisand Enterolobium contortisilicuum, species characteristic of Chacobiome (e.g. Acacia), and exotic species such asGleditsia triacanthos

and Psidium guajaba (Chalukian, 1992; De Viana and Colombo-

Speroni, 2000; Grau and Aragón, 2000). Morus alba and Ligustrumlucidum are natives from China. Birds feed their fruits, dispersingtheir seeds at distant locations where they may germinate andbecome established (Tolaba, 1996). L. lucidum is extremelyinvasiveandformsdense monospecific layersinside forests (Batcher, 2000).G. triacanthosisadeciduoustreeofthesoutheasternofNorthAmer-ica (Burton and Bazzaz, 1995). Within Yungas forest, cattle grazetheir fruits, dispersing their seeds wherever they move (Quirogaet al., unpublished results). This specie has expanded in San JavierHill, displacing native vegetation (Grau and Aragón, 2000). Acaciamacracantha, Acacia caven and Schinus bumellioides are typical of Chaco biome (Zuloaga and Morrone, 2011). The presence of thesespecies in Yungas streams was restricted to areas disturbed by cat-tle (Saravia Toledo, 1996; Quiroga et al., unpublished results). L.

camara and A. donax have been nominated as one of the top 100




worstinvaders of theworldby theinvasive species specialist groupof the World Conservation Union (Lowe et al., 2000). The facility of A. donax to invade river banks added to its high water requirement(Boose and Holt, 1999) would determinate the importance of thisspecie as threat to the integrity of the riparian zone. The success of L. camara in the riparian ecosystems maybe attributed to the largenumber of fruits per plant (Kohli et al., 2004; Parveen, 2010), theability to grow under a wide range of climatic conditions (Day etal., 2003), andthe release of allelochemicalsby roots (Ambika et al.,2003). The explicit invasion of L. camara in riparian zones has beenrecently reported in India (Parveen et al., 2011).

In some riparian areas of the piedmont and hillside of Yungas,native vegetation had been replaced by species of Pinus and Euca-

lyptus. Monospecific forestry practices have been considered as analternative to restore degraded lands with the potential to becomediverse in the long-term (Lugo, 1997; Parrota et al., 1997). Pre-liminary observations in San Javier Hill suggested that Pinus andEucaliptus would promote the recovery of native forest and wouldprovide habitat for birds (Vides-Almonacid, 1992).

The negative consequences of the introduction of exotic speciesare evident in some sectors of Lules River sub-basin, resulting insignificant changes in the physiognomy of the landscape, seemlyto a forest with xerophytic characteristics than one correspondingto the Yungas biome (Quiroga et al., unpublished results).

The historic use of Lules vegetation as feeding area for livestockdeterminates the name of Potrero de las Tablas (site 13) constitut-ing with sites 12 and 19, a path for cattle movement. In addition,the natural condition of riparian vegetation of some sites such as15 was related to their inaccessible physiographical characteristicsthat make difficult the introduction of people and cattle.

Agricultural expansion, construction of roads, intense aridextraction, dump of solid and industrial waste, modification of flu-vial terraces constraining the river channel, introduction of rigidstructures in the channel and along the margins, were some of theimpacts that deteriorated the cover, structure and quality of thestreams andriparianvegetation of the eastern side of the San JavierHill. Abandonedfieldsof citrusplantationsare commonin this sub-

basin. After some years of abandonment, the secondary vegetationhasastructurethatresultsattractiveforbirdsallowingthearrivalof pioneersnativespeciessuchasCinamommumporphyrium, Solanumriparium, Urera caracasana and the exoticMorus spp. (Grau, 2004).

This study is the first in the northwestern of Argentina to adaptan index to evaluate the quality of riparian vegetation. The QBRyindex represents a useful tool to identify sites where stream andriparian vegetation are severely impaired or pristine, and thosewhere conservation effort should be directed. The introduction of exotic species representsa realproblemthat threatensthe integrityof the Yungas forest. In addition, this study highlights the impor-tance of a protected area for conservation of the quality of riparianvegetation. Within Yungas where riparian corridors acts as refugeto a great variety of plants and animals, the protection of the few

existing well-preserved riparian sites and the necessity of restora-tion of highly altered riparian ones becomes an essential priorityfor biodiversity sustainability.

Finally, this work represents the first approximation of a pro-tocol that can be applied in other Yungas basins. We suggest toevaluate thestatus of riparian vegetation in conjunction with otherbiological indicators in order to obtain a holistic view of the healthof these lotic systems.

Acknowledgments

Special thanks to Ramón Luis Imbert for his assistance in mapdiagram. We greatly appreciate to Dr. Mercedes Marchese andDr. Carolyne Stephens for their constructive suggestions. We are

also grateful to the two anonymous reviewers for their comments

that significantly improved the manuscript. This study was sup-ported by ILINOA, Research Program No. 26/G446-1, Ministerio deCiencia y Tecnología, Universidad Nacional de Tucumán and Con-sejo Nacional de Investigaciones Científicas y Técnicas (CONICET).

Appendix A.

List of riparian species relative to the three studied sub-basins.Origin and habit are also shown.

Taxa Origin Habit

Acacia caven (Molina) Molina var. caven Exotic Tree Acacia macracantha Humb. & Bonpl. ex Willd. Exotic Tree Acacia praecox Griseb. Native Tree Allophylus edulis (St. Hill.) Radlkofer Native Tree Aloysia gratissima (Gill. ex Hook. et Arn.) Hicken Native Shrub Anadenanthera colubrina (vell .) Bernan Ver (gr ises)atschul Native Tree Arundo donax L. Exotic ReedBaccharis salicifolia (Ruiz et Pav.) Persoon Native ShrubBlepharocalyx salicifolius (H.B.K.) O.Berg. Native TreeBoehmeria caudataSw. Native ShrubCarica quercifolia (St.Hil.) Solms-Laub. Native TreeCassia carnaval Speg. Native TreeCedrela lilloi C. DC. Native TreeCeltis iguanaea (Jacq.) Sarg. Native ClimberCestrum parqui L’Hér. Native ShrubCestrum strigillatum Ruiz & Pav. Native ShrubChamissoa altísima (Jacq.) H.B.K. Native ClimberCinnamomumporphyrium(Griseb.) Kosterm. Native TreeCupania vernalisCambess. Native TreeDuranta serratifolia (Griseb.) Kuntze Native TreeEnterolobium contortisiliquum(Vell. Conc.) morong Native TreeEriobotrya japonica (Thunb.) Lindl. Exotic TreeEucalyptus sp. Exotic TreeEugenia unifloraL. Native TreeEupatorium lasiophtalmunGriseb. Native ShrubGleditsia triacanthos L. Exotic TreeGrevillea robusta A. Cunn. Exotic TreeGuaduaangustifoliaKunth Exotic ReedHeliocarpuspopayanensisH.B.K. Native Tree Jacaranda mimosifolia D.Don Native Tree Juglans australisGriseb Native TreeLantana camara L. Exotic ShrubLigustrum lucidum W.T. Aiton Exotic TreeLycium cestroidesSchldl. Native TreeManihot grahamiiHook. Exotic TreeMorus alba L. Exotic TreeMyrcianthes cisplatensis (Cambess.) O. Berg Native TreeMyrcianthes mato (Griseb.) McVaugh Native TreeMyrcianthes pungens (Ver) Legrand Native TreeMyrsine laetevirens (Mez ) rechav. Native TreeParapiptadenia excelsa (Griseb.) Burkart Native TreePersea americana Mill. Exotic TreePhenax laevigatusWedd. Native ShrubPhyllostylon rhamnoides (J. Poiss.) Taub. Native TreePinus sp Exotic TreePiper hieronymiC DC. Native TreePiper tucumanumC. DC. Native TreePisonia ambigua Heimerl Native TreePisoniella arborescens var. glabrata Heimerl Native ClimberPrunus tucumanensis Lillo Native TreePsidium guajava L. Exotic TreePsychotria carthagenensis Jacq. Native ShrubPyracantha angustifolia (Franch.) C.K. Schneid. Exotic ShrubRicinus communisL. Exotic ShrubRubus imperialis Cham. & Schltdl Native ClimberRuprechtia laxiflora Meisn. Native TreeSalix humboldtiana Willd. Native TreeSambucus peruvianumH.B.K. Native TreeSchinus bumelioides Johnst. Exotic TreeSenecio peregrinusGriseb. Native ShrubSolanum ripariumPers. Syn. Native TreeTabebuia avellanedae Lorentz ex Griseb. Native TreeTecoma stans (L.) Juss. ex H. B. K. Native TreeTerminalia triflora (Griseb.) Lillo Native TreeTessaria integrifolia Ruiz et Pavon Native TreeTipuana tipu (Benth.) O. Kuntze Native TreeTremamicrantha (L.) Blume Native TreeUrera baccifera (L.) Gaud Native TreeUrera caracasana (Jacq.) Gaudich ex Griseb Native TreeVerbesina suncho(Griseb.) S.F. Blake Native ShrubVernonia fultaGriseb. Native ClimberVernonia squamulosaHook. et. Arn. Native Shrub Xylosma pubescens Griseb. Native Tree Zanthoxilum fagara (L.) Sarg. Native Tree Zanthoxilum naranjilloGriseb. Native Tree




Appendix B.



http://www.darwin.edu.ar/publicaciones/catalogovascII/atalogovascII.asp

http://www.darwin.edu.ar/publicaciones/catalogovascII/atalogovascII.asp

http://www.issg.org/database

Documents

QBRy a Method for Assessing the Ecological Quality of Riparian Forests