Influence of Altitude and Climatic Factors on the Floristic Composition of the Moorlands of the Guamote Canton, Ecuador: Key Revelations for Conservation

Abstract

The Andean paramos are unique and biodiverse environments. Located between the upper limit of forest and perpetual snow, they provide ecosystem services, especially freshwater supply; however, anthropogenic activities and climate change have altered their distribution and composition. This paper analyses the influence of altitude and climatic factors on the floristic composition of the páramos. A quasi-experimental study was used in three altitudinal gradients, collecting geolocalised data on species and bioclimatic variables. Principal component analysis, using the HJ-Biplot visualisation technique and k-means clustering algorithms, was applied to explore the relationships between factors. It was determined that the lower zone is nuanced by the presence of Solanaceae, which are important for human food. In the middle zone, there is a high diversity, with the Ericaceae and Caprifoliaceae families standing out, while in the upper zone, the Ericaceae and Gentianaceae families are accentuated. The PCA reveals that strata 2 and 3 share family taxa, while stratum 1 shows differences. Altitude and precipitation directly influence the distribution of species in each stratum; the Asteraceae family is dominant in the canton for its contribution to the principal components.

1. Introduction

The Andean paramos are part of the neotropical high mountain ecosystems in the Andes. They play an important role in maintaining water balance and providing buffering for living beings, and above all provide a large part of the drinking water supply for high Andean cities and towns. They are characterised by maintaining a low temperature throughout the year, i.e., they have a cold climate with high seasonal variability, with annual rainfall ranging from 700 to 3000 mm. These characteristics give rise to lake habitats, such as lakes and lagoons around the paramos mountains, which contribute significantly to the region’s biodiversity.

Mountain ecosystems are globally recognised for conservation. They are included in SDG 15 of the Sustainable Development Goals of the United Nations’ 2030 Agenda. In addition, they are ecosystems that stand out for their great biodiversity, excellent richness, and high level of endemism. In particular, the soils belonging to the paramos have great carbon storage capacity due to their own vegetation layer, which is highly relevant for mitigation and adaptation to climate change. Therefore, they are ecosystems declared of critical importance for their conservation and environmental balance [1,2,3,4,5,6].

These ecosystems have an estimated area of 24,301 km² distributed across South America [7]. In Ecuador, about 5% of the land area is paramo—located between the upper limit of the Andean forest and the lower limit of glaciers or perpetual snow—which are essential for the provision of ecosystem services, including carbon storage and the maintenance of biodiversity. Paramos host 15% of the world’s total plant richness, with about 500 genera and 5000 plant species, of which 60–80% are endemic [8,9,10]. The main families are Asteraceae, Orchidaceae, Melastomataceae, and Poaceae [11].

The Ecuadorian paramos have experienced an annual area reduction of 0.8% over a period of 28 years, which is an urgent environmental problem since grasslands are being replaced by pastures, fallow vegetation, and crops [12,13]. In addition, the high rates of turnover and their rapid speciation processes cause variations in their floristic structure and composition [14,15]. Niche contraction and expansion and community reorganisation in response to climate warming are affecting the distribution of the paramos flora, highlighting the dynamic nature of these ecosystems [16]. It is projected that between 10% and 47% of Andean endemic species could face extinction by 2100 due to these environmental changes [17].

In this context, we analyse the influence of altitude and climatic factors on the composition and floristic distribution of the Andean moorlands of the Guamote Canton in order to identify if there are specific patterns of diversity or dominance of families in each altitudinal gradient.

2. Materials and Methods

2.1. Study Area

The study area is located in Ecuador in the province of Chimborazo in the Canton of Guamote, with an area of 1200.081 km². It is located in the Ecuadorian Andes at altitudes between 2600 and 4503 m above sea level, at coordinates 1°56′00″ S 78°43′00″ O. The area receives total precipitation of 683.3 mm per square meter and an average temperature of 13.7 °C, presenting climates such as alpine tundra (ET), temperate with dry winter (Cwb), and subtropical highlands (Cfb) [18] (Figure 1).

This study was developed under a quasi-experimental relational approach, using three altitudinal gradients as natural laboratories to evaluate the impact of geomorphological factors on ecology, biodiversity, and ecosystem dynamics. This approach allows for the analysis of species distribution responses to climatic variations, providing a basis for assessing plant richness and conservation value in mountain landscapes [19,20,21]. The methodological process was structured in three phases as follows (Figure 2):

2.2. Delimitation of Altitudinal Gradients

Three altitudinal gradients were defined based on the minimum and maximum elevations of the canton, using intervals greater than 550 m. Each gradient reflects changes in the environmental conditions and floristic composition [22]. The delimitation was carried out using official cartographic information from the Military Geographic Institute (IGM), under the WGS84 reference system and UTM coordinates (zone 17 south), with an altitudinal resolution of 40 m. With QGIS software version 3.40.1, a digital terrain model was generated using specific tools such as create TIN, TIN to raster, reclassify, and raster to polygon, which facilitated data classification and transformation [23]. The gradients were defined as outlined below:

Stratum 1 (2600–3254 m.a.s.l.): areas with roads, buildings, and agricultural activities, covering 17,186.8 ha;

Stratum 2 (3255–3907 m.a.s.l.): rural areas dedicated to agriculture, livestock, forest plantations, and undisturbed moorland, covering 77,209.7 ha;

Stratum 3 (3908–4503 m.a.s.l.): grasslands and shrublands for conservation and grazing, covering 25,611.6 ha.

2.3. Database of Floristic Species and Bioclimatic Variables

A database of floristic species and environmental variables was compiled from multiple sources, such as the Espoch–Herbarium repository, GBIF, online herbarium (Tropics and Austral Americano) and scientific articles indexed in Scopus and Web of Science. This information was complemented with 18 floristic inventories carried out in the moorlands of the Cebadas and Palmira parishes across three years, in the framework of the project “Determination of the efficient use of biopurifying high Andean plant species” [24].

The georeferenced data were validated and standardised using the Flora Neotropica criteria, resolving taxonomic and spatial inconsistencies [25]. Bioclimatic variables were obtained from WorldClim v2.0, with a spatial resolution of 30 s and a base period of 1970–2000. Nineteen indicators derived from temperature and precipitation data were included and fitted to each gradient using the Extract by mask tool [26].

2.4. Multivariate Analysis

For the data analysis, two main tables were constructed: one relating altitudinal gradients to floristic families, and the other linking bioclimatic variables to strata. The HJ-Biplot method implemented in the MULTBIPLOT version 16.430.0.0 software was used, which allows for handling multiple variables and facilitates the visualisation of complex relationships [27].

Principal component analysis (PCA) was used to reduce the dimensionality of the data, identify significant patterns, and simplify interpretation [28,29,30].

For the principal component analysis, the data were standardised using the formula $Z={\displaystyle \frac{X-\mu }{\sigma }}$, where X is the original value, μ is the mean of the variable, and σ is the standard deviation. Then, the covariance matrix was calculated by the formula $S={\displaystyle \frac{1}{n-1 }}{\sum }_{i-1}^n(Xi-\overline{X}\left)\right(Xi-\overline{X}{)}^T$. The eigenvalues and eigenvectors of the covariance matrix were then obtained as $S\nu =\lambda \nu$, where v is the eigenvector and λ is the corresponding eigenvalue. Then, the principal components were formed. Further, $Y=XV$, where V is the matrix of eigenvectors. Finally for the visualisation in the HJ-Biplot—which allows for simultaneously representing the observations and the variables in a two-dimensional space—the coordinates of the observations are equal to $F=XA$, where A are the first two eigenvectors scaled by the square root of their respective eigenvalues, and the coordinates of the variables are equal to $G=V{\bigwedge }^{1/2}$, where V is the matrix of eigenvectors and Λ is the diagonal matrix of eigenvalues.

The results were visualised using HJ-Biplot, and complemented with k-means clustering to optimise the classification of floristic families [31,32].

3. Results

3.1. Floristic Characterisation by Altitudinal Gradients

A total of 4789 georeferenced records of high Andean species distributed in three altitudinal strata of Guamote County were validated, identifying 229 species belonging to 90 families. Stratum 2 had the highest diversity with 61.6%, followed by stratum 1 with 21.4%, and stratum 3 with 17%.

Stratum 1 recorded 49 species distributed in 21 families, with Asteraceae being the most diverse (18.4%), followed by Lamiaceae, Amaranthaceae, Solanaceae, Poaceae, and Verbenaceae (>6%). Solanaceae and Lamiaceae stand out and are relevant for their medicinal, food, and construction use, especially in rural communities [33,34,35,36].

Stratum 2 has 141 species distributed in 47 families; this stratum is characterised by the predominance of Asteraceae (15.6%), followed by Ericaceae, Caprifoliaceae, Cyperaceae, and Onagraceae (>4%). Ericaceae stands out for its adaptation to acid soils and for its taxonomic and morphological diversity [37,38,39]. Caprifoliaceae is also relevant for its distribution in mountainous areas and its ecological and pharmacological value [40,41].

In stratum 3, 39 species belonging to 22 families were recorded, with Asteraceae presenting the highest diversity (20.5%), followed by Ericaceae (17.9%), Gentianaceae, Hypericaceae, Poaceae, and Rosaceae (>5%). Gentianaceae stands out for its characteristics in the biosynthesis of pharmacologically important compounds. Poaceae, on the other hand, is a fundamental family in the moorlands, contributing significantly to the biosynthesis of pharmacologically important compounds [42,43,44] as well as to the structure and function of the ecosystem [45,46].

3.2. Contribution of Bioclimatic Variables to Altitudinal Gradients

Principal component 1 explains 99.93% of the variance of the data, with variables Bio 12, 16, 17, 18, and 19 being the largest contributors and related to the amount of precipitation (Figure 3).

It should be noted that the bioclimatic variables related to temperature show low contributions in component 1; therefore, it is determined that their influence is low or almost null in the spatial distribution of floristic species.

3.3. Contribution of Families to Altitudinal Gradients

The first principal component explains 72.9% of the variance of the data, the second component 20.6%, and the third principal component 6.4%. It should also be considered that stratum 2 has a high contribution to the component analysis or axis 1, stratum 3 has a moderate contribution, and stratum 1 has a low degree of contribution (Figure 4).

The family with the greatest influence on the total variability represented by principal component 1 is Asteraceae, which characterises and infers a dominant presence in the Andean paramo.

In addition, the families Araliaceae, Blechnaceae, Boraginaceae, Davalliaceae, Dryopteridaceae, Gesneriaceae, Loasaceae, Loranthaceae, Nyctaginaceae, Phytolaccaceae, Polygonaceae, and Tropaeolaceae stand out with values above 900 units, indicating that they share common characteristics or attributes that contribute significantly to the variability observed in the data (

Table 1. Household contributions per row.

Contributions per Row	Axis 1	Axis 2	Axis 3	Contributions per Row	Axis 1	Axis 2	Axis 3
Amaryllidaceae	92	175	733	Grossulariaceae	966	27	7
Apiaceae	1	993	6	Iridaceae	966	27	7
Amaranthaceae	14	934	52	Lamiaceae	345	633	21
Apocynaceae	109	809	82	Lycopodiaceae	298	403	299
Araliaceae	966	27	7	Malvaceae	109	809	82
Asteraceae	995	5	0	Oleaceae	625	300	74
Berberidaceae	26	29	946	Loasaceae	966	27	7
Brassicaceae	109	809	82	Loranthaceae	966	27	7
Bromeliaceae	398	437	165	Melastomataceae	367	149	484
Blechnaceae	966	27	7	Nyctaginaceae	966	27	7
Boraginaceae	966	27	7	Onagraceae	794	39	167
Calceolariaceae	819	65	116	Piperaceae	607	393	1
Caprifoliaceae	332	98	570	Orchidaceae	121	793	85
Caryophyllaceae	625	300	74	Pentaphyllacaceae	390	172	438
Crassulaceae	625	300	74	Orobanchaceae	367	149	484
Campanulaceae	367	149	484	Oxalidaceae	756	84	160
Coriariaceae	298	403	299	Phytolaccaceae	966	27	7
Cunoniaceae	298	403	299	Plantaginaceae	756	84	160
Cyperaceae	239	367	393	Poaceae	325	246	429
Davalliaceae	966	27	7	Polygalaceae	145	1	854
Dryopteridaceae	966	27	7	Polanaceae	354	518	128
Equisetaceae	298	403	299	Polygonaceae	966	27	7
Ericaceae	602	363	36	Otamogetonaceae	390	172	438
Escalloniaceae	298	403	299	Tropaeolaceae	625	300	74
Fabaceae	821	95	84	Verbenaceae	1	934	65
Gentianaceae	251	721	28	Ranunculaceae	756	84	160
Hypericaceae	251	721	28	Rosaceae	343	656	0
Geraniaceae	756	84	160	Rubiaceae	5	169	826
Gesneriaceae	966	27	7	Tropaeolaceae	966	27	7

).

The main contribution to the principal component 2 is characterised by the Apiaceae family.

3.4. Grouping

Clustering analysis using the k-means algorithm suggests that strata 2 and 3 share family taxa, while stratum 1 has a large Euclidean distance for each data point (families) and the centroid of its assigned group.

Group or cluster 1 gathers 16 families (28%) that are located close to the vectors of the three strata, indicating that they are common families and species at all three altitudinal levels (Figure 5).

Group 2 brings together 72% of families that share a similar spatial distribution and similar environmental and ecological conditions but are not very common in the three strata, which are as follows: Amaryllidaceae, Apiaceae, Apocynaceae, Araliaceae, Berberidaceae, Brassicaceae, Bromeliaceae, Blechnaceae, Boraginaceae, Caryophyllaceae, Crassulaceae, Campanulaceae, Coriariaceae, Cunoniaceae, Davalliaceae, Dryopteridaceae, Equisetaceae, Escalloniaceae, Geraniaceae, Gesneriaceae, Grossulariaceae, Iridaceae, Lycopodiaceae, Malvaceae, Oleaceae, Loasaceae, Loranthaceae, Melastomataceae, Nyctaginaceae, Piperaceae, Orchidaceae, Pentaphyllacaceae, Orobanchaceae, Oxalidaceae, Phytolaccaceae, Plantaginaceae, Polygonaceae, Potamogetonaceae, Tropaeolaceae, Ranunculaceae, and Rubiaceae (

Table 2. Families and characteristic species in the three altitudinal strata.

Family	Species
Asteraceae	Ambrosia arborescens, Achilea millefolium, Baccharis latifolia, Baccharis prunifolia, Baccharis emarginata, Baccharis teindalensis, Baccharis macrantha, Monticalia arbutifolia, Monticalia stuebelii, Gynoxys hallii, Gynoxys buxifolia, Taraxacum officinale, Plagiocheilus sp., Grosvenoria campii, Gazania rigens, Chaptalia sp., Conyza bonariensis, Ageratina pichinchensis, Gamochaeta americana, Ageratina sp., Hieracium frigidum, Lucilia sp., Antennaria sp., Tridax stuebelii, Viguiera quitensis, Tagetes multiflora, Diplostephium glandulosum, and Lasiocephalus involucrata
Amaranthaceae	Alternanthera sp.
Calceolariaceae	Calceolaria ferruginea
Caprifoliaceae	Valeriana cernua, Valeriana microphylla, Valeriana plantaginea, Valeriana decusata, and Sambucus nigra
Cyperaceae	Uncinia phleoides, Rhynchospora vulcani, Rhynchospora macrochaeta, Schoenoplectus californicus, and Carex pichinchensis
Ericaceae	Ceratostema alatum, Disterigma empetrifolium, Gaultheria sp., Pernettya prostrata, Macleania sp., and Vaccinium floribundum
Fabaceae	Medicago polymorpha, Lupinus, Trifolium, and Mimosa quitensis
Gentianaceae	Halenia gracilis, Gentianella rapunculoides, and Gentianella diffusa
Hypericaceae	Hypericum strictum, Hypericum lancifolium, Hypericum lancioides, and Hypericum quitense
Lamiaceae	Salvia corrugata, Salvia macrostachya, Salvia leucophylla, Salvia sagittata, Marrubium vulgare, Stachys elliptica, and Clinopodium nubigenum
Onagraceae	Fuchsia loxensis, Fuchsia hybrida, Fuchsia vulcanica, and Oenothera epilobiifolia
Poaceae	Agrostis perennans, Neurolepis aristata, Bromus pitensis, Stipa ichu, and Cortaderia jubata
Polygalaceae	Monnina crassifolia
Solanaceae	Solanum radicans, Solanum siphonobasis, Solanum colombianum, Solanum aloysiifolium, Solanum interandinum, Solanum barbulatum, Capsicum annuum var. Anuu, and Nicotiana sp.
Verbenaceae	Stachytarpheta sp.
Rosaceae	Rubus adenotrichos, Lachemilla orbiculata, Acaena elongata, Hesperomeles obtusifolia, and Lachemilla nivalis

).

4. Discussion

The bioclimatic variables related to precipitation were determinant in the floristic composition, which is consistent with research that emphasises the influence of precipitation on the diversity and distribution of plant species [47,48,49,50]. This emphasises the importance of incorporating climate change scenarios in future conservation studies, given their possible alteration of precipitation patterns and their impact on paramos ecosystems.

The results and prior research papers collectively support the claim that the mid-Andean páramos zone harbours a high diversity of plant species and families, and report a rich floristic diversity [51,52,53]. Other research underlines the importance of this diversity by documenting traditional knowledge of plant use in the tropical fringe of the Paramillo National Natural Park [36]. All these studies support the claim that the mid-Andean páramos zone is a hotspot of plant diversity [53].

In the páramos of the Guamote Canton, the Asteraceae family significantly dominates the floristic composition, which has been supported by several studies. For example, it has been found that this family is one of the richest in species in the paramos, accompanied by Poaceae, Ericaceae, and Orchidaceae [54,55]. Furthermore, this dominance has been confirmed by other authors, who identified a high species richness of Asteraceae in the Bajío region. The relevance of this family is also highlighted by its use in traditional Andean medicine [56,57], which underlines its cultural and functional importance. In the context of the Andean paramo, the diversity of the Asteraceae family is remarkable, especially in the high Andean forests and paramos, where it is manifested in the presence of 28 genera and 44 species of wild Asteraceae with medicinal uses in two communities in southern Peru, according to [57,58].

Component 2 has a high contribution of Apiaceae, which is a diverse and widely distributed group [59]. In the paramos of northwestern Colombia, the family is one of the most diverse, along with Orchidaceae and Melastomataceae [60]. The family is also present in the Venezuelan Andes, where it is one of the most species-rich families [54].

5. Conclusions

It is evident that the distribution of floristic species in the Andean moorlands of Guamote is strongly influenced by altitude as each altitudinal gradient is characterised by taxa of specific families: for stratum 1 these are Solanaceae and Lamiaceae, which are families used for their nutritional and medicinal properties by the community members of the rural areas of the Guamote Canton, who cultivate in the moorland areas; in stratum 2 or the middle zone, the Ericaceae and Caprifoliaceae families are widely distributed with chemical constituents such as iridoids and flavonoids, used in natural medicine due to their possible health benefits; stratum 3 is characterised by the presence of Ericaceae, Gentianaceae, Hypericaceae, Poaceae, and Rosaceae, which are plants from temperate-cold climates and mountainous areas and are used as natural pastures.

The bioclimatic variables derived from precipitation Bio 12, 16, 17, 18, and 19 condition the distribution of the families in each stratum, creating ideal conditions for plant development; the variables related to temperature show low contributions in the principal components.

Among the three altitudinal gradients, 25% of the family diversity is shared; however, most have specific stratified spatial distributions that differ within each stratum. This finding is consistent with previous research, highlighting the importance of these factors in determining plant species composition and diversity.

The middle stratum has the greatest diversity of species and families, while the lower and upper strata show less diversity. Several families were identified that characterise the moorlands of the Guamote Canton, mainly Asteraceae, as well as Ericaceae, Caprifoliaceae, among others. These families play a crucial role in the structure and functioning of the paramos ecosystems, and their presence is related to particular adaptations to the environmental conditions of high-altitude zones. Asteraceae is the dominant family, widely distributed at all three altitudinal levels, with the greatest influence on the total variability and with the highest species diversity compared to the other families.