DOI: 10.5061/dryad.dv41ns1vf
title: Conversion of Andean montane forests into plantations: effects on soil characteristics, microorganisms and microarthropods

description: Tropical montane forests in the Andes are subjected to deforestation and
 subsequent transformation into pastures. Abandoned pastures are frequently
 reforested by planting monoculture timber plantations, resulting in
 reduced aboveground diversity and changes in soil characteristics compared
 to primary forests. In this study, we evaluated differences in soil
 properties (litter layer thickness, pH, water content and C-to-N ratio)
 between degraded primary montane forest and monoculture pine (Pinus
 patula) and alder (Alnus acuminata) plantations and their effect on
 density, diversity and community structure of litter and soil living
 mesofauna, with focus on oribatid mites (Acariformes). The study was
 performed in a montane region in the southern Ecuadorian Andes (2000-2600
 m a.s.l.). C-to-N ratios in the litter and upper 5 cm soil layer were
 higher in pine plantations, while other soil characteristics were similar
 between vegetation types. Surprisingly, microbial biomass and density of
 soil mesofauna in the litter layer did not differ between vegetation
 types, while density and species richness of oribatid mites were higher in
 pine plantations. Community structure of oribatid mites differed between
 vegetation types with only few species overlapping. The results indicate
 that quality and diversity of litter were not the major factors regulating
 the mesofauna community. Instead, soil animals benefit from increased
 habitat structure in thicker litter layers and potentially increased
 availability of root-derived resources. Overall, the results suggest that
 from a soil animal perspective, monoculture plantations are less
 detrimental than commonly assumed and enrichment of abandoned plantations
 with native tree species may help to restore tropical montane forests.
description: Twelve study sites were selected in the Loja valley between 2400
 and 2600 m a.s.l.: (1) four pine and (2) four alder plantations, and (3)
 four degraded forests (Figure 1). In each forest fragment/plantation, one
 experimental plot of 24 x 24 m was established. Within each plot four
 samples were taken at randomly selected points, resulting in a total of 48
 sampling points for each investigated parameter. We used a soil corer 5 cm
 in diameter. Each core was divided into O horizon (litter layer) and Ah
 horizon (5 cm of mineral soil underneath the litter layer), which were
 analysed separately for all parameters, except Oribatida species numbers,
 which were only assessed in the litter layer. For
 measuring carbon (C) and nitrogen (N) concentrations, an aliquot of both
 the litter and mineral soil was milled to powder;  3-4 mg were analysed
 for C and N concentrations using an elemental analyser (Vario EL III,
 elementar, Hanau, Germany) (Butenschoen et al., 2014; Marian, Sandmann,
 Krashevska, Maraun, & Scheu, 2017). Water content in both layers
 was measured from aliquots dried at 60°C for two days.
 Samples for microbial parameters were placed in plastic bags,
 stored at 4°C and transferred to Germany. Microbial basal respiration (BR)
 and substrate-induced respiration (SIR) were determined by measuring
 O<sub>2</sub> consumption using a computer controlled
 O<sub>2</sub> microcompensation apparatus (Scheu, 1992). Prior
 to measurement, an aliquot of leaf litter was cut into pieces &lt; 0.5
 cm² and the soil was sieved through 2 mm mesh and mixed thoroughly. Before
 measuring, the samples were rested for 4 days at room temperature to avoid
 including increased basal respiration caused by cutting of leaf litter and
 homogenization. Moist samples equivalent to 0.2 (litter) and 2 (soil) g
 dry weight were supplemented with glucose equivalent to 80 (litter) and 8
 (soil) mg g<sup>−1</sup> dry weight, and BR was measured for
 24 h with readings taken every hour. Microbial biomass
 (C<sub>mic</sub>) was calculated from the maximum initial
 respiratory response (MIRR; μl O<sub>2</sub>
 g<sup>−1</sup> dry weight h<sup>−1</sup>) as
 C<sub>mic</sub> = 38 × MIRR (Anderson & Domsch, 1978;
 Beck et al., 1997; Joergensen & Scheu, 1999).
 Mobile soil animals were extracted by heat within 24 h after
 sampling (Kempson, Lloyd, & Ghelardi, 1963). Extracted animals
 were stored in 70% ethanol and transferred to Germany. Most animal groups
 were determined to order, suborder or cohort level using Schaefer (2010)
 except for adult oribatid mites, which were determined to species level or
 sorted into morphospecies.
description: <b>ReadMe:</b>
 Abbreviations and explanations for the dataset Environmental data and
 fauna <b>forest_type:</b> samples
 were taken in three forest types. alder:
 Monoculture plantations of Andean alder (<i>Alnus acuminata
 </i>Kunth) plantations pine: Monoculture
 plantations of pine (<i>Pinus patula </i>Schiede &
 Deppe) degraded_forest: remnants of degraded primary
 tropical montane rainforest 
 <b>forest.ID: </b>Identification number assigned to
 each forest fragment used as a random factor during statistical
 analysis. <b>sampling_plot:</b> each
 sampling plot within each forest fragment was assigned a number between
 one and four <b>layer:</b> layers into
 which the sampled soil cores were separated (O horizon (litter layer) and
 Ah horizon (5 cm of mineral soil underneath the litter layer))
 <b>water.cont: </b>given as<b>
 </b>percentage of total fresh weight
 <b>Ctotal:</b> total percentage of carbon (C) in the
 soil/litter samples, given in percentage [%]
 <b>Ntotal:</b> total percentage of nitrogen (N) in
 the soil/litter samples, given in percentage [%]
 <b>C/N ratio: </b>ratio of carbon to nitrogen in
 the<b> </b>soil/litter samples <b>BR:
 </b>Microbial basal respiration [µg O2*h-1*g soil dw-1]
 <b>Cmic:</b> Microbial biomass [µg Cmic*g soil
 dw-1] <b>total_fauna</b>: Abundance of all
 movable soil fauna (individuals per soil core)
 Oribatida, Collembola, Mesostigmata: abundance of the respective
 soil fauna group (individuals per soil core)
 Oribatida_species
 <b>forest_type:</b> samples were taken in three
 forest types. alder:
 Monoculture plantations of Andean alder (<i>Alnus acuminata
 </i>Kunth) plantations pine: Monoculture
 plantations of pine (<i>Pinus patula </i>Schiede &
 Deppe) degraded_forest: remnants of degraded primary
 tropical montane rainforest 
 <b>forest.ID: </b>Identification number assigned to
 each forest fragment used as a random factor during statistical
 analysis. <b>sampling_plot:</b> each
 sampling plot within each forest fragment was assigned a number between
 one and four <b>Nr.: </b>Number for
 internal classification system of morphospecies. Not relevant for data
 analysis <b>Sex: </b>Reproductive mode of
 the respective oribatid mite species parth:
 parthenogenetic reproduction sex: sexual
 reproduction