Corresponding author: Mirian Roxana Calderon (
Urbanization is one of the main causes driving changes in biodiversity patterns and it is regarded as a major threat to native biota. Successful exotic plant invasion depends on invasiveness and invasibility. Invasiveness is related to the characteristics of exotic plants and invasibility to the features of the sites. The objective of this study was to identify the invasibility environmental factors affecting the success of exotic plant invasion in a wildland-urban ecotone of the central region of Argentina (Potrero de los Funes Village, San Luis). Fifty phytosociological inventories were recorded in an area of 700 ha during spring and summer seasons (2013–2015). Abundance-coverage values of plants and environmental variables such as soil characteristics, anthropogenic disturbance, and altitude of the sites were assessed. Soil moisture, electrical conductivity (
A urbanização é uma das principais causas das mudanças nos padrões de biodiversidade sendo considerada uma grande ameaça à biota nativa. O sucesso exitoso da invasão das plantas exóticas depende da invasividade e invasibilidade. A invasividade está relacionada com às características das plantas exóticas e à invasibilidade com às características dos locais. O objetivo deste estudo foi identificar os fatores ambientais de invasibilidade que afetam o sucesso da invasão das plantas exóticas em ecótono urbano-silvestre na região central da Argentina (Potrero de los Funes, San Luis). Cinquenta inventários fitossociológicos foram registrados em uma área de 700 ha durante as estações primavera e verão (2013–2015). Valores de cobertura-abundância das plantas e variáveis ambientais, como características do solo, perturbação antropogênica e altitude dos sítios foram avaliadas. A umidade do solo, condutividade elétrica, acidez (
Successful exotic plant invasion depends on invasiveness and invasibility. Invasiveness is related to the characteristics or biological traits of exotic plants (
Several soil characteristics have been associated with plant invasion (
The province of San Luis, Argentina is characterized by a low industrial development in contrast with accelerated urban growth (
The objective of this study was to identify the invasibility environmental factors affecting the success of exotic plant invasion in a wildland-urban ecotone. We hypothesize that the abundance-coverage of exotic plants is positively influenced by high soil moisture, organic matter content, nitrate concentration, neutral
The village of Potrero de los Funes is located in the southwest portion of the Sierras de San Luis System in San Luis province, central region of Argentina (Fig.
Locations of the 50 plots in Potrero de los Funes Village, San Luis province, central region of Argentina, used for soil sampling and phytosociological inventories during spring and summer seasons from 2013–2015.
An anthropogenic disturbance index was used to evaluate the level of anthropogenic disturbance of each site (
The 23 anthropogenic disturbance factors assessed in order to estimate the degree of human disturbance surrounding each site in Potrero de los Funes, San Luis province, central region of Argentina.
Anthropogenic disturbance index | |
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Cattle faeces | Water extraction pipes |
Stray animals, breeding centres | Mining activity |
Overgrazing | Dams, reservoirs |
Agricultural areas | Channelization |
Clearing, wood extraction | Stormwater/sewer drainage pipes |
Construction debris | Diverted channels |
Soil Erosion | Isolated channels |
Density of houses | Presence of gabions |
Proximity to city/town | Bridges |
Human trails and gravel/dirt roads | Landfill, urban solid waste disposal areas |
Paved roads | Others |
Constructions for recreational purposes | |
Evidence of fires |
Four soil samples were taken from the root zone with a 6 cm diameter cylinder and within the 10–30 cm in depth in each plot. Measured soil parameters included gravimetric moisture, electrical conductivity (
Satellite images were used to identify homogenous vegetation areas and the number of plots needed to perform a representative vegetation survey of the study area (700 ha). Fifty plots were established at random. Plot size was determined for each vegetation type using the minimal area method, meaning that the plot had to be large enough to represent community composition (
Two data matrices representing environmental variables and vegetation abundance-coverage were constructed and the PC-ORD 5.0 software package was used for multivariate statistical analysis (Non-metric Multidimensional Scaling;
The anthropogenic disturbance index varied among plots from values below 10 for the most preserved plots (ESPIN, MOLLE, CORTA) to values close to 20 for the most disturbed plots (CYNO, CARDA, CARDALCA). The altitude of the sites ranged from 911 m a.s.l. (CYNO1) to 1099 m a.s.l. (SOPHO11). Soil chemical characteristics also varied among plots, mainly in the nitrate content (Table
Anthropogenic Disturbance Index values, altitude and soil chemical parameters (average ± standard error) at the plots in Potrero de los Funes, San Luis province, central region of Argentina.
Plot ID | Anthropogenic disturbance index | Altitude (m a.s.l.) | Soil moisture (%) |
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Organic matter (%) | Nitrates (ppm) | |
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7 | 979 | 2.20±0.002 | 0.6±0.12 | 6.95±0.06 | 0.7±0.02 | 13.8±0.25 |
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8 | 997 | 2.20±0.0015 | 0.6±0.1 | 6.95±0.07 | 0.7±0.03 | 12.2±0.28 |
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8 | 920 | 0.80±0.002 | 1.35±0.13 | 7.97±0.1 | 0.45±0.01 | 13±0.31 |
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7 | 1009 | 2.20±0.03 | 0.6±0.12 | 6.95±0.05 | 0.7±0.02 | 13.2±0.45 |
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7 | 978 | 2.20±0.03 | 0.6±0.1 | 6.95±0.1 | 0.7±0.032 | 13.3±0.19 |
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8 | 980 | 2.54±0.002 | 0.22±0.1 | 7.42±0.07 | 0.81±0.01 | 12±0.18 |
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6 | 998 | 1.61±0.0041 | 0.23±0.1 | 5.47±0.07 | 0.81±0.02 | 12.6±0.27 |
|
9 | 999 | 2.20±0.002 | 0.6±0.12 | 6.95±0.1 | 0.7±0.025 | 11±0.21 |
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11 | 967 | 17.16±0.01 | 0.53±0.08 | 6.54±0.1 | 1.18±0.01 | 31±0.8 |
|
11 | 968 | 17.20±0.01 | 0.54±0.07 | 6.44±0.1 | 1.2±0.01 | 28±0.7 |
|
12 | 962 | 8.55±0.02 | 0.7±0.07 | 5.57±0.06 | 1.2±0.005 | 13.5±0.31 |
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10 | 992 | 8.55±0.04 | 0.6±0.05 | 5.5±0.05 | 1.21±0.01 | 9±0.2 |
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12 | 969 | 2.70±0.03 | 0.69±0.07 | 5.7±0.05 | 1.19±0.01 | 12±0.3 |
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11 | 994 | 8.55±0.04 | 0.65±0.05 | 5.6±0.06 | 1.22±0.01 | 10.2±0.27 |
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9 | 988 | 22.03±1.2 | 0.27±0.03 | 6.96±0.1 | 0.25±0.003 | 7.7±0.13 |
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9 | 973 | 28.1±1.3 | 0.26±0.05 | 7±0.06 | 0.21±0.004 | 3.1±0.08 |
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8 | 991 | 25.04±1.2 | 0.25±0.05 | 6.8±0.07 | 0.23±0.002 | 5.6±0.15 |
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9 | 958 | 20.02±1.3 | 0.28±0.06 | 6.78±0.07 | 0.2±0.006 | 6.2±0.17 |
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8 | 943 | 20.08±1.5 | 0.24±0.05 | 6.96±0.06 | 0.27±0.003 | 7±0.17 |
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9 | 968 | 5.9±0.1 | 0.3±0.05 | 7.61±0.1 | 1.1±0.002 | 28±0.89 |
|
10 | 990 | 9.92±0.4 | 0.13±0.04 | 6.81±0.03 | 0.72±0.002 | 23±0.7 |
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10 | 963 | 4.1±0.3 | 0.28±0.05 | 8.71±0.05 | 0.31±0.002 | 26±0.65 |
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9 | 984 | 10.00±0.5 | 0.13±0.02 | 6.81±0.07 | 0.72±0.003 | 24.5±0.72 |
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10 | 964 | 10.02±0.4 | 0.14±0.01 | 7±0.07 | 0.71±0.005 | 28.2±0.68 |
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9 | 961 | 0.65±0.02 | 0.13±0.02 | 6.81±0.08 | 0.72±0.005 | 28.1±0.73 |
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17 | 970 | 15.14±0.6 | 0.42±0.01 | 7.05±0.05 | 1.03±0.01 | 11.5±0.35 |
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18 | 1039 | 15.14±0.7 | 0.48±0.02 | 6.95±0.1 | 1.05±0.01 | 13±0.25 |
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18 | 1039 | 15.50±0.5 | 0.42±0.02 | 6.87±0.06 | 1.04±0.013 | 25±0.9 |
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20 | 964 | 15.16±0.4 | 0.41±0.01 | 7.01±0.07 | 1.03±0.015 | 22±0.61 |
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17 | 911 | 0.8±0.003 | 1.35±0.06 | 7.97±0.1 | 0.45±0.03 | 31.5±0.82 |
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18 | 955 | 4.1±0.05 | 0.28±0.01 | 8.71±0.13 | 0.31±0.02 | 28.8±0.75 |
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18 | 976 | 10.00±0.5 | 0.25±0.01 | 7.96±0.15 | 0.44±0.02 | 32±0.65 |
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19 | 984 | 9.95±0.5 | 0.23±0.02 | 7.89±0.11 | 0.49±0.03 | 30±0.77 |
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18 | 963 | 9.00±0.4 | 0.25±0.01 | 8±0.1 | 0.47±0.02 | 29±0.91 |
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6 | 1028 | 3.30±0.2 | 0.14±0.01 | 6.87±0.09 | 0.26±0.01 | 14.8±0.4 |
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6 | 1083 | 3.19±0.3 | 0.28±0.01 | 6.29±0.07 | 0.64±0.02 | 39.1±0.7 |
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5 | 998 | 3.24±0.17 | 0.2±0.01 | 6.5±0.06 | 0.50±0.02 | 15±0.5 |
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6 | 971 | 3.20±0.2 | 0.28±0.02 | 6.29±0.06 | 0.64±0.023 | 13±0.45 |
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9 | 975 | 14.50±0.7 | 0.17±0.01 | 7.77±0.05 | 0.89±0.02 | 15.6±0.65 |
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8 | 962 | 13.60±0.5 | 0.25±0.01 | 7.96±0.07 | 0.44±0.02 | 12±0.51 |
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8 | 1099 | 25.00±0.8 | 0.21±0.01 | 7.66±0.05 | 0.5±0.022 | 22.5±0.48 |
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9 | 965 | 25.66±0.7 | 0.23±0.01 | 7.76±0.06 | 0.53±0.021 | 20±0.52 |
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8 | 991 | 15.66±1.2 | 0.21±0.02 | 7.69±0.07 | 0.52±0.03 | 15±0.56 |
|
4 | 970 | 10.56±0.8 | 0.17±0.02 | 6.99±0.05 | 0.98±0.01 | 12.65±0.36 |
|
5 | 1011 | 11.00±0.62 | 0.15±0.01 | 7.1±0.08 | 0.96±0.02 | 12±0.37 |
|
12 | 959 | 16.12±0.6 | 0.083±0.001 | 5.55±0.08 | 1.11±0.016 | 13.5 6±0.4 |
|
11 | 965 | 5.65±0.34 | 0.093±0.002 | 5.65±0.07 | 1.21±0.01 | 15±0.38 |
|
10 | 964 | 7.29±0.41 | 0.4±0.01 | 6.95±0.09 | 1.02±0.01 | 15.6±0.41 |
|
9 | 948 | 7.70±0.5 | 0.42±0.02 | 7.09±0.05 | 1.12±0.01 | 22.3±0.6 |
|
12 | 954 | 7.50±0.3 | 0.44±0.01 | 6.98±0.07 | 1.52±0.016 | 25.6±0.7 |
Fifty phytosociological inventories were performed at the area of study (see Suppl. material
Species list of 105 taxa registered during the phytosociological inventories performed in Potrero de los Funes, San Luis province, central region of Argentina, from 2013–2015. Exotic species are indicated in bold.
Species | Code | Species | Code |
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abugra | jodrho | ||
acapoi | justwe | ||
acabun | langri | ||
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alogra | lepcri | |
amebra | lipjun | ||
anetom | litmol | ||
bacart | lorvis | ||
bacfla | malvas | ||
bacsal |
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rombac | melmac | ||
baculi |
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bidpil | nasten | ||
bidsub |
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botspr | oxacon | ||
boucur | paposp | ||
bowinc | pasdil | ||
brocru |
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celehr | pormic | ||
cespar | procal | ||
chapsp | pronig | ||
chebuc |
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rhoasp | |
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clemon | schfas | ||
colspi | schplu | ||
comere | sensub | ||
conmic | setlac | ||
corsel | setpar | ||
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sidspi | |
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solela | |
desero |
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dicmic |
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eryhor | soplin | ||
eupden | symsqu | ||
eusret | tagmin | ||
evoari |
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evoser | cleacu | ||
floool | tesabs | ||
galric |
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galpar | typdom | ||
geodec |
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glalil | urtcir | ||
heisal | vacast | ||
hetova | vaccav | ||
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hydbon |
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iredif |
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iporub |
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jarpse | zinper | ||
jarich |
The percentage of exotic plants species within the plots varied from 0% in the most preserved sites (ESPIN, SOPHO, CHILFLO) to 70% in the most disturbed sites (CARDA, CARDALCA). The abundance-coverage of exotic species also varied among plots with some dominated by exotics (CARDA, CYNO, HETERO). The minimum stress of the three axes in the NMDS ordination was 17.9. As part of the NMDS analysis, the Monte Carlo test showed a
Plot ordination of non-metric multidimensional scaling (NMDS) based on the abundance-coverage data of plant species in Potrero de los Funes Village, San Luis province, central region of Argentina. Black dots represent the plots and the vectors the environmental variables related to NMDS axes (cutoff level
The following species were associated with axis 1:
Species ordination of non-metric multidimensional scaling (NMDS) plot based on abundance-coverage data. Black dots represent the species and vectors of the environmental variables related to NMDS axes (cutoff level
The plant communities related with higher altitudes were the ones dominated by “mollares” of
Exotic plant communities dominated by
Spearman’s correlation test confirmed that anthropogenic disturbance was the variable most strongly correlated with the percentage of exotic plants (
In accordance with the hypothesis established in this investigation, a strong positive relationship between anthropogenic disturbance and abundance-coverage of exotic plants was found. Many researchers have arrived at similar conclusions and reported that anthropogenic disturbance is a key factor in invasion success (
In the last three decades, the area of study has experienced an increase in population growth, urbanization, and tourism influx that may explain the success of invasion reflected in our results. Most of the exotic plants found in the area of study were intentionally introduced as ornamentals and for landscaping purposes around houses, camping areas and recreational establishments. Additionally, unintentional human-mediated dispersal through contaminated footwear and clothes along hiking trails within the area may contribute to the expansion of the exotic plant distribution (
A positive relationship between nitrate concentration in soil and patterns in vegetation distribution was found. Spearman’s correlation test showed a significant relationship between nitrogen and the percentage of exotic plants, and hence available soil nitrogen in the area was an important soil characteristic related with the invasibility of the species found. Nitrogen availability is known to be important in limiting the primary production in terrestrial ecosystems (
A negative relationship was found between abundance-coverage of exotic species with altitude, which was consistent with observations from other investigations (
Through the NMDS analysis, it was possible to identify a weak relationship between the pattern of vegetation distribution and soil moisture. Additionally, no significant correlation was found when the Spearman correlation test was applied. Although the presence and abundance of invasive plants is usually favored by the increase of soil moisture (
A weakly positive correlation between
No correlation between organic matter and exotic plants was observed in this study.
Anthropogenic disturbance, nitrate concentration, and altitude were the most important factors influencing the success of exotic plant invasion in Potrero de los Funes. This study provides the first insight regarding the relationships between exotic plant success and site characteristics in a natural-urban gradient ecosystem of the central area of Argentina.
We gratefully acknowledge Instituto de Química de San Luis “Dr. Roberto Olsina” – Consejo Nacional de Investigaciones Científicas y Tecnológicas (INQUISAL-CONICET) and Universidad Nacional de San Luis (Project PROICO 2-1914 and PROICO 3-0716) for financial support. We thank Rebecca Meissner and Robert Coville for the valuable language and grammar revision of the manuscript. Finally, we would like to thank two anonymous reviewers for their comments that helped to improve the quality of this manuscript.
Phytosociological inventories performed in Potrero de los Funes from 2013-2015
measurement