1. Introduction
Macrophytes are the primary producers of freshwater ecosystems and are essential for several biotic interactions [
1]. These ecosystems have endemic species that move between watercourses, but they are highly invasive due to the high pressure of propagules [
2]. In-vasive exotic species can cause changes in the native community, such as the extinction of macrophytes, amphibians, and fish [
1]; it is estimated that spending on biological inva-sions since 1970 in the world has been approximately US
$ 1.3 trillion [
3].
Urochloa subquadripara (Trin) R.D. Webster, “tenner-grass” (synonymous with
Brachiaria subquadripara,
Brachiaria arrecta, and
Urochloa arrecta) [
4,
5,
6] is an emergent macro-phyte, rooted near the margins, which has long, floating branches, forming mats on the surface of the water [
7,
8]. It is a Poaceae native to Africa and invasive in tropical and sub-tropical regions [
9].
Due to the easy propagation by stolons, rhizomes, or fragments that can be trans-ported in water, the invasion of
U. subquadripara raises concerns about water use and the suppression of biodiversity [
8,
10]. In addition, the species can grow as an epiphytic life form, rooted on the banks but extending on the surface of the water using floating macro-phytes such as Pistia stratiotes and
Eichhornia crassipes as support [
11].
Urochloa subquadripara colonizes natural and artificial water bodies [
12], occurring in Brazil in areas such as the Pantanal [
13], Cerrado and Atlantic Forest [
14]. In addition, it is problematic in hydroelectric reservoirs such as Barra Bonita (SP) [
15], Funil (MG) [
16] and Santana (RJ) [
17]. The invasive potential of
U. subquadripara varies according to biotic and abiotic factors [
18].
The invasion of
U. subquadripara correlates with the composition of the native com-munity, varying in different spatial scales [
6]. At more minor scales, the similarity be-tween native and invasive species can result in competition; however, at larger spatial scales, the probability of occurrence increases with the richness of native macrophytes [
19,
20,
21]. The co-occurrence between native and invasive species is explained by the "Theory of biotic acceptance", which suggests that the presence of native species is positively cor-related with the occurrence of invasive species [
22,
23].
The occurrence of
U. subquadripara is associated, on a large scale, with emerging and floating native macrophytes, of which the genus Eichhornia and Salvinia stand out [
7,
19].
Eichhornia crassipes is a Pontederiaceae native to the Amazon basin in Brazil and Ecuador, considered an invasive of water bodies and reservoirs worldwide [
24].
Salvinia minima is a macrophyte native to Mexico, Central, and South America [
25], and due to its rapid growth, it is also considered a problematic weed [
26].
The distribution of macrophytes is largely related to climatic regions, limited by in-creasing latitude and altitude [
27,
28]. Climate changes, mainly temperature, and precipi-tation, will influence the regime of water masses, which may reduce the volume and in-crease the water temperature of lakes and reservoirs [
28,
29,
30]. Thus, climate changes in-terfere with the habitat of macrophytes, altering growth, reproduction, development [
31], phenology, distribution, and species migration [
32]. Emerging and floating macrophytes such as
U. subquadripara,
E. crassipes, and
S. minima are more prone to impacts related to changes in temperature since they are more exposed than submerged macrophytes [
33].
Some approaches, such as species distribution models (SDMs), can be adopted for ecological niche projection considering the climate [
34]. SDMs allow for predicting the po-tential distribution of a species using occurrence and climate data [
35], being an important tool in preventing the invasion of exotic species in new environments. The CLIMEX soft-ware generates SDMs from the Ecoclimatic Index (EI) based on the growth and stress pa-rameters of the species under study [
36]. This methodology has been widely used for modeling the ecological niche of invasive species and weeds [
37,
38,
39,
40,
41].
Thus, the potential distribution of an invasive species can be determined by paying attention only to the climate, but the integrated understanding of the factor that influences the invasive potential, such as the co-occurrence of species, allows the filtering of suitable places [
35]. Multicriteria decision-making (MCDM) is an alternative tool combining several criteria in a single index [
42]. Within MCDM, the analytical hierarchy process (AHP) is widely used and consists of comparing the criteria, which ensures greater relia-bility in the judgment of assigned weights [
43].
Therefore, due to the invasive capacity of U. subquadripara, the risk to ecosystems and natural communities, and disturbances in reservoirs, it is necessary to study the potential distribution of the species to develop control strategies to minimize possible impacts. This study aimed to develop a potential distribution model for U. subquadripara using the CLIMEX software. In addition, to determine the potential distribution of E. crassipes and S. minima and, based on multicriteria decision-making, correlate the climatically suitable areas for native species with areas suitable for the occurrence of the invasive species.
Author Contributions
Tayna Sousa Duque: Conceptualization, Formal analysis, Investigation, Writing - Original Draft, Writing - Review & Editing. Iasmim Marcella Souza: Formal analysis, Investigation, Writing - Original Draft, Writing- Review & Editing. Débora Sampaio Mendes: Formal analysis, Investigation, Writing - Original Draft. Ricardo Siqueira da Silva: Conceptualization, Methodology, Resources, Writing - Review & Editing. Danielle Piuzzana Mucida: Resources, Writing - Original Draft, Writing - Review & Editing, Supervision. Francisca Daniele da Silva: Writing - Review & Editing. Daniel Valadão Silva: Writing - Review & Editing, Resources. José Barbosa dos Santos: Conceptualization, Methodology, Resources, Writing - Original Draft, Writing - Review & Editing.
Figure 1.
Weighted combination of criteria matrix datasets.
Figure 1.
Weighted combination of criteria matrix datasets.
Figure 2.
(a) Known global distribution of Urochloa subquadripara plants and (b) Ecoclimatic Index (EI) for U. subquadripara, modeled using CLIMEX. Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 2.
(a) Known global distribution of Urochloa subquadripara plants and (b) Ecoclimatic Index (EI) for U. subquadripara, modeled using CLIMEX. Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 3.
Current distribution of Urochloa subquadripara in validation regions, native (African continent) and invaded area (South America), based on the Ecoclimatic Index (EI). Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 3.
Current distribution of Urochloa subquadripara in validation regions, native (African continent) and invaded area (South America), based on the Ecoclimatic Index (EI). Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 4.
(a) Known global distribution of Eichhornia crassipes plants and (b) Ecoclimatic Index (EI) for E. crassipes, modeled using CLIMEX. Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 4.
(a) Known global distribution of Eichhornia crassipes plants and (b) Ecoclimatic Index (EI) for E. crassipes, modeled using CLIMEX. Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 5.
Current distribution of Eichhornia crassipes in validation regions, native area (South America), and invaded area (United States of America and Mexico), based on the Ecoclimatic Index (EI). Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 5.
Current distribution of Eichhornia crassipes in validation regions, native area (South America), and invaded area (United States of America and Mexico), based on the Ecoclimatic Index (EI). Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 6.
(a) Known global distribution of Salvinia minima plants and (b) Ecoclimatic Index (EI) for S. minima, modeled using CLIMEX. Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 6.
(a) Known global distribution of Salvinia minima plants and (b) Ecoclimatic Index (EI) for S. minima, modeled using CLIMEX. Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 7.
Current distribution of Salvinia minima in validation regions, native area (South America), and invaded area (United States of America and Mexico), based on the Ecoclimatic Index (EI). Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 7.
Current distribution of Salvinia minima in validation regions, native area (South America), and invaded area (United States of America and Mexico), based on the Ecoclimatic Index (EI). Unsuitable areas in white (EI = 0), low suitable in light orange (0 <EI <30), and high suitable in orange (30 ≤EI ≤ 100).
Figure 8.
(a) Climate suitability for Urochloa subquadripara considering co-occurrence with native species (Eichhornia crassipes and Salvinia minima), considering Ecoclimatic Indices (EI) modeled using CLIMEX. Inappropriate areas in white (0) and very suitable areas in red (1); (b) global lakes and wetlands database (GLWD), including tier 1 (lakes with surface area ≥50 km2 and reservoirs with storage capacity ≥0.5 km3) and tier 2 (lakes, reservoirs and rivers with surface area ≥0.1.
Figure 8.
(a) Climate suitability for Urochloa subquadripara considering co-occurrence with native species (Eichhornia crassipes and Salvinia minima), considering Ecoclimatic Indices (EI) modeled using CLIMEX. Inappropriate areas in white (0) and very suitable areas in red (1); (b) global lakes and wetlands database (GLWD), including tier 1 (lakes with surface area ≥50 km2 and reservoirs with storage capacity ≥0.5 km3) and tier 2 (lakes, reservoirs and rivers with surface area ≥0.1.
Table 1.
Adjusted parameter values for modeling the invasive species Urochloa subquadripara (US) and native Eichhornia crassipes (EC) and Salvinia minima (SM) using CLIMEX.
Table 1.
Adjusted parameter values for modeling the invasive species Urochloa subquadripara (US) and native Eichhornia crassipes (EC) and Salvinia minima (SM) using CLIMEX.
Parameters |
Index |
Unit. |
US |
EC |
SM |
Lower temperature threshold |
DV0 |
ºC |
4 |
0.5 |
5 |
Lower optimum temperature |
DV1 |
ºC |
22 |
25 |
23 |
Upper optimum temperature |
DV2 |
ºC |
35 |
30 |
30 |
Upper optimum threshold |
DV3 |
ºC |
39 |
36 |
39 |
Lower soil moisture threshold |
SM0 |
-- |
0 |
0 |
0.1 |
Lower optimum soil moisture |
SM1 |
-- |
0.1 |
0.1 |
0.2 |
Upper optimum soil moisture |
SM2 |
-- |
8 |
8 |
8 |
Upper soil moisture threshold |
SM3 |
-- |
10 |
10 |
10 |
Cold stress temperature threshold |
TTCS |
ºC |
4 |
0.5 |
5 |
Cold stress temperature rate |
THCS |
Week-1
|
-0.001 |
-0.0003 |
-0.0003 |
Cold stress degree-day threshold |
DTCS |
ºC day |
4 |
---- |
---- |
Cold stress degree-day rate |
DHCS |
Week-1
|
-0.01 |
---- |
---- |
Heat Stress Temperature threshold |
TTHS |
ºC |
40 |
37 |
39 |
Heat Stress Temperature rate |
THHS |
week-1
|
0.01 |
0.001 |
0.1 |
Heat Stress Threshold |
DTHS |
ºC dia |
39 |
---- |
35 |
Heat Stress Degree-day rate |
DHHS |
week-1
|
0.01 |
---- |
0.1 |
Dry Stress Threshold |
SMDS |
-- |
0.1 |
0.02 |
---- |
Dry Stress rate |
HDS |
week-1
|
0.005 |
-0.005 |
|
Degree-days threshold |
PPD |
ºC dia |
---- |
1916 |
---- |
Table 2.
Criteria used in multicriteria decision-making, classes, and normalized values.
Table 2.
Criteria used in multicriteria decision-making, classes, and normalized values.
Criteria |
Criterion |
Description |
Criterion 1 |
Ecological niche for U. subquadripara
|
Criterion 2 |
Ecological niche for E. crassipes
|
Criterion 3 |
Ecological niche for S. mínima
|
Criteria Classes |
Description |
Classe |
Normalized value |
EI = 0 |
0 |
0 |
0>EI>30 |
1 |
0.5 |
EI>30 |
2 |
1 |
Table 3.
Paired comparison matrix describing preferences between the criteria identified in table 2.
Table 3.
Paired comparison matrix describing preferences between the criteria identified in table 2.
|
Criterion 1 |
Criterion 2 |
Criterion 3 |
Criterion 1 |
1 |
5 |
5 |
Criterion 2 |
0.2 |
1 |
1 |
Criterion 3 |
0.2 |
1 |
1 |
Table 4.
Weights used in multicriteria decision making.
Table 4.
Weights used in multicriteria decision making.
Criterion |
Description |
Weight* |
Criterion 1 |
Ecological Niche para U. subquadripara
|
0.714 |
Criterion 2 |
Ecological Niche para E. crassipes
|
0.143 |
Criterion 3 |
Ecological Niche para S. minima
|
0.143 |