Study area
The research was conducted in two areas with the greatest distribution of pine and eucalyptus plantations in southern Ecuador. Both eucalyptus (Eucalyptus globulus Labill.) and pine (Pinus patula Schiede ex Schltdl. & Cham.) plantations are known worldwide as introduced species that arrive in Latin America to reforest degraded areas and satisfy the demand for timber (Anchaluisa and Suárez R. 2013).
Ecuador has a land area of 28'356,000 ha, of which it is estimated that 14.4 million hectares of land are under forest use, that is, more than 50% of the national territory. Forest plantations cover approximately 164,000 ha, representing 1.14% of Ecuador's forest area, made up of Eucalyptus sp. (43%), Pinus sp. (30%) and other native and exotic species (27%). Ninety percent of plantations are located in the inter-Andean region, 8% on the coast, and 2% in eastern Ecuador (Merizalde-Veliz et al. 2023).
Natural and planted forests play an important role in preserving ecological balance, so their use is regulated and protected to ensure the maintenance of various ecosystems. They have great importance and adaptability in the inter-Andean lands of Ecuador, since they grow in hard, muddy, sandy soils located on slopes and high pastures (FAO 1981; Cisternas et al. 1999).
The province of Loja is influenced by its geographical location, and the Huancabamba Depression facilitates the development of fauna, flora, and ecosystems (Aguirre Mendoza 2017). It has a variety of climates: High Mountain Equatorial, Dry Mesothermal Equatorial, and Semi-Humid Mesothermal Equatorial. Rainfall varies between 758–1250 mm. The rainy season lasts from November to May. The relative humidity fluctuated between 80% and 88%, and the temperature was between 8–27 degrees Celsius.
We selected three land use types for each area: 1) forest, 2) eucalyptus plantations, and 3) pinus plantations (Table 1). For each land use type, we designated two localities separated by at least 1 km (Fig. 1; Table 1).
Table 1
Coordinates and altitude per land use: forest, pinus, and eucalyptus, and study area: Loja and Saraguro. For each land uses we selected two sites.
Area
|
Land uses
|
Codes
|
Coordinates
|
Altitude (m a.s.l.)
|
Latitud
|
Longitud
|
Area 1
(Loja)
|
Forest
|
FL1
|
-4.036
|
-79.196
|
2207
|
FL2
|
-4.047
|
-79.174
|
2383
|
Pinus
|
PL1
|
-4.014
|
-79.192
|
2220
|
PL2
|
-4.033
|
-79.196
|
2218
|
Eucalyptus
|
EL1
|
-4.015
|
-79.214
|
2204
|
EL2
|
-4.034
|
-79.198
|
2195
|
Area 2 (Saraguro)
|
Forest
|
FS1
|
-3.660
|
-79.268
|
2963
|
FS2
|
-3.683
|
-79.270
|
2944
|
Pinus
|
PS1
|
-3.615
|
-79.266
|
2877
|
PS2
|
-3.652
|
-79.263
|
2962
|
Eucalyptus
|
ES1
|
-3.615
|
-79.250
|
2615
|
ES2
|
-3.611
|
-79.230
|
2353
|
Dung beetle sample
To analyze the dung beetle communities, we set up three transects of 300 m each, separated by 100 m. We installed six pitfall traps per transect at 0, 150, and 300 m. The traps remained in the field for 48 h. The traps consisted of plastic containers 12 cm in diameter and 9 cm deep and were placed at ground level with a mixture of water and detergent. Each trap was baited with 30 g of decomposing pig manure. The captured samples were then placed in polyethylene bags containing 90% ethyl alcohol. For this sample, we have tried to follow the methodologies proposed by (Nunes et al. 2021; Mora-Aguilar et al. 2023) for the neotropic.
The samples were then separated and identified to the species level in the laboratory of the Museum of Zoology (CISEC-MUTPL) using taxonomic keys according to (Chamorro et al. 2018, 2019) and compared with the reference collection of the "Colección de Invertebrados Sur del Ecuador CISEC-MUTPL.”
Morphometric measurement
To characterize functional diversity based on traits, we randomly selected and measured five individuals per species and per land use (Salas-Lopez et al. 2018; Salomão et al. 2021). We selected nine morphological traits based on bibliographical research (Alves and Hernández 2017; Soto et al. 2019; Marín‐Armijos et al. 2023). Measured morphological features:1. HL = Head length, 2. HW = Head width, 3. PL = Pronotum length; 4. PW = Pronotum width, 5. PH = Pronotum height; 6. EL = Length of elytra, 7. pTL = length of the protibia; 8. pTW = width of the protibia, and 9. mTL = length of metatibia (Fig. 2).
Biomass was measured by species and for the entire assemblage in each land use, following (Seibold et al. 2019), using the following formula:
Where L (length) is the sum of the head length, pronotum length, and elytra length of the individual and/or species sampled in millimeters.
Data analysis
Taxonomic diversity
The dung beetle community was analyzed using hill numbers for each land use for data based on richness (q = 0) and diversity (q = 1 and q = 2) (Chao et al. 2014). We also performed non-metric multidimensional analysis (NMDS), based on the Bray-Curtis index, using the abundance data obtained to graphically express the grouping patterns and differences in species composition. We verified the differentiation of the communities according to habitats with different land uses through a multivariate analysis of variances (Permanova), using the function adonis, with 999 permutations using the vegan package (Oksanen et al. 2019).
The INDVAL species indicator was used to select habitat indicator species, which is based on the degree of specificity (exclusivity to a particular habitat) and fidelity (frequency of occurrences within the same habitat) of the species (Dufrene and Legendre 1997).
To evaluate the abundance distribution, we performed a rank abundance curve, which shows the relative abundance of species and their uniformity within each land use, providing essential information for predicting changes in community patterns and allowing us to better explain how the dominance and distribution of species behaved in each land use (Whittaker et al. 2001).
To evaluate the effects of land use (forest, pine, and eucalyptus plantations) on the composition of dung beetles, Generalized Linear Models (GLMs) were applied using the Poisson distribution in the R software package (R-Core-Team 2019), which helped measure the incidence of the three land uses to the number of coprophagous beetles found in the sampling.
Functional diversity based on morphological traits
For the simple reduction of the data sets with graphical representation and to position the species in the functional trait space, principal component analysis (PCA) was performed using R software (R-Core-Team 2019).
A linear mixed model was used to evaluate the effects of land use (forest, pine, and eucalyptus plantations) on the morphological traits of dung beetles. It allows multiple nested or crossed random effects, computes profile confidence intervals, and conducts parametric bootstrapping (Bates et al. 2015). Sites were included as random intercepts to avoid potential non-independence among land use types within the same area. All analyses were performed using the R software (R-Core-Team 2019).