Montane Forests In Southern Ecuador Research Articles

Genetic diversity and structure in two epiphytic orchids from the montane forests of southern Ecuador: The role of overcollection on Masdevallia rosea in comparison with the widespread Pleurothallis lilijae.

Ecuador has a high diversity of orchids, but little is known about levels of genetic diversity for the great majority of species. Understanding how orchids might adapt to changes is crucial as deforestation and fragmentation of forest ecosystems threaten the survival of many epiphytic orchids that depend on other species, such as fungi and their host trees, for germination, growth, and establishment. Overcollection and the illegal trade are also major concerns for the survival of wild populations of orchids. Despite increasing awareness, effective interventions are often limited by a lack of data concerning the impacts that overexploitation might have. To fill this gap, we tested the effects of overcollection in the genetic diversity and structure of Masdevallia rosea, a narrow distributed epiphytic orchid historically collected in Ecuador, in comparison with the widely distributed Pleurothallis lilijae. Genotyping based on AFLPs showed reduced levels of diversity in wild populations but most especially in the overcollected, M. rosea. Overall, genetic admixture was high in P. lilijae segregating populations by altitude levels while fewer genetic groups were found in M. rosea. Genetic differentiation was low in both species. A spatial genetic structure was found in P. lilijae depending on altitude levels, while no spatial genetic structure was found in M. rosea. These results suggest different scenarios for the two species: while gene flow over long distance is possible in P. lilijae, the same seems to be unlikely in M. rosea possibly due to the low levels of individuals in the known populations. In situ and ex situ conservation strategies should be applied to protect the genetic pool in these epiphytic orchid species, and to promote the connectivity between wild populations. Adopting measures to reduce overexploitation and to understand the impacts of harvesting in wild populations are necessary to strengthen the legal trade of orchids.

Moderate phosphorus additions consistently affect community composition of arbuscular mycorrhizal fungi in tropical montane forests in southern Ecuador.

Anthropogenic atmospheric deposition can increase nutrient supply in the most remote ecosystems, potentially affecting soil biodiversity. Arbuscular mycorrhizal fungal (AMF) communities rapidly respond to simulated soil eutrophication in tropical forests. Yet the limited spatio-temporal extent of such manipulations, together with the often unrealistically high fertilization rates employed, impedes generalization of such responses. We sequenced mixed root AMF communities within a seven year-long fully factorial nitrogen (N) and phosphorus (P) addition experiment, replicated at three tropical montane forests in southern Ecuador with differing environmental characteristics. We hypothesized: strong shifts in community composition and species richness after long-term fertilization, site- and clade-specific responses to N vs P additions depending on local soil fertility and clade life history traits respectively. Fertilization consistently shifted AMF community composition across sites, but only reduced richness of Glomeraceae. Compositional changes were mainly driven by increases in P supply while richness reductions were observed only after combined N and P additions. We conclude that moderate increases of N and P exert a mild but consistent effect on tropical AMF communities. To predict the consequences of these shifts, current results need to be supplemented with experiments that characterize local species-specific AMF functionality.

Geomorphology and Altitude Effects on the Diversity and Structure of the Vanishing Montane Forest of Southern Ecuador

(1) Background: Neotropical montane forests represent one of the most diverse world ecosystems; however, they are also among the most threatened ones mostly due to deforestation. Our main goal is to classify and clarify the forest types based on the changes in basal area (BA), tree density, and species composition of montane forests in Southern Ecuador, and to determine the influence of critical environmental and geomorphological factors. (2) Methods: One hundred thirty-two temporary plots of 400 m2 were installed in homogeneous and well-conserved forest stands. We identified and measured all trees >10 cm diameter breast height (DBH). We modeled species diversity (Fisher’s alpha) change in relation to climatic, altitudinal, and geomorphological gradients using GLM and Kruskall-Wallis analyses. The change in composition was determined using cluster analyses (BIOENV analysis followed by a LINKTREE procedure). Non-metric multidimensional scaling (NMDS) was used to analyze changes across climatic and geomorphological gradients. Finally, we used a SIMPER analysis to identify the species that contributed most to the floristic dissimilarity among the identified altitudinal forests types. (3) Results: The floristic groups were determined by altitude, temperature, and isothermality, but also some geomorphological variables and lithology were used. Plots located in low hills have higher alpha diversity compared to the high hills and dissected mountains. (4) Conclusions: Altitude is the most important factor responsible for the division of structural and floristic groups. In addition, those plots located on the whitish tuff have higher alpha value diversity compared with plots in andesitic tuffs. Precipitation on the wettest quarter (>839 mm) and isothermality (>90.5) are the most relevant climatic factors driving the floristic classification.

Elevation‐dependent effects of forest fragmentation on plant–bird interaction networks in the tropical Andes

Tropical forests harbor diverse ecological communities of plants and animals that are organized in complex interaction networks. The diversity and structure of plant–animal interaction networks may change along elevational gradients and in response to human‐induced habitat fragmentation. While previous studies have analyzed the effects of elevation and forest fragmentation on species interaction networks in isolation, to our knowledge no study has investigated whether the effects of forest fragmentation on species interactions may differ along elevational gradients. In this study, we analyzed main and interaction effects of elevation and forest fragmentation on plant–frugivore interaction networks at plant and bird species level. Over a period spanning two years, we recorded plant–frugivore interactions at three elevations (1000, 2000 and 3000 m a.s.l.) and in two habitat types (continuous and fragmented forest) in tropical montane forests in southern Ecuador. We found a consistent effect of elevation on the structure of plant–frugivore networks. We observed a decrease in the number of effective bird partners of plants and, thus, a decline in the redundancy of bird species with increasing elevation. Furthermore, bird specialization on specific plant partners increased towards high elevations. Fragmentation had a relatively weak effect on the interaction networks for both plant and bird species, but resulted in a significant increase in bird specialization in fragmented forests at high elevations. Our results indicate that forest fragmentation may have stronger effects on plant–frugivore interaction networks at high compared to low elevations because bird species richness declined more steeply towards high elevations than plant species richness. We conclude that conservation efforts should prioritize the maintenance of consumer diversity, for instance by maintaining stretches of continuous forest. This applies in particular to species‐poor communities, such as those at high elevations, as the ecological processes in these communities seem most sensitive towards forest fragmentation.

Contrasting species responses to continued nitrogen and phosphorus addition in tropical montane forest tree seedlings

AbstractGlobal changes in nutrient deposition rates are likely to have profound effects on plant communities, particularly in the nutrient‐limited systems of the tropics. We studied the effects of increased nutrient availability on the seedlings of six tree species in montane forests of southern Ecuador in situ. After five years of continued N, P, or N+P addition, naturally grown seedlings of each of the two most common species at each elevation (1000, 2000, and 3000 m asl) were harvested for analyses of leaf morphology, nutrient content, herbivory, and tissue biomass allocation. Most species showed increased foliar N and P concentrations after addition of each respective element. Leaf tissue N:P ratios of >20 in the control plants of all species suggest that P is more growth‐limiting in these forests than N. Leaf morphological responses to nutrient addition were species and nutrient specific, with some species (Hedyosmum purparescens, Graffenrieda emarginata) exhibiting increased specific leaf area (SLA), and others (Graffenrieda harlingii) increased leaf area ratios (LAR). Pouteria torta (1000 m) had lower SLA and LAR after P addition. Increased herbivory was only evident in G. emarginata (after N and N+P addition). Only the species from 3000 m asl modified biomass allocation after nutrient addition. In general, N and N+P addition more strongly affected the species studied at the upper elevations, whereas P addition had a similar range of effects on the species at all elevations. We conclude that the responses of the studied tropical montane forest tree seedlings to chronic N and P addition are highly species‐specific and that successful adaptation to increased nutrient availability will depend on species‐specific morphological and physiological plasticity.

Elevation and topography influence community structure, biomass and host tree interactions of lianas in tropical montane forests of southern Ecuador

AbstractQuestionsHow does the structure of liana communities (diameter, density and biomass) in tropical montane forests vary along elevation and topographic gradients? How do patterns of tree infestation vary with elevation? Is tree diameter growth reduced by lianas in tropical montane forest?LocationTropical Andean forests (1000–3000 m a.s.l.) in the San Francisco Reserve and in the Podocarpus National Park, southern Ecuador.MethodsAll lianas (DBH ≥ 1 cm) were censused in 54 permanent plots (20 × 20 m) equally distributed between three study sites (1000, 2000 and 3000 m a.s.l.) and three topographic positions (lower, mid and upper slope) per site (six replicate plots at each site by position combination). The DBH and number of lianas hosted was recorded for all trees (DBH ≥ 10 cm). Liana biomass was estimated using allometric equations. ANOVAs were used to test for effects of elevation and slope positions on liana parameters and proportion of trees infested. The relationships between liana biomass and tree parameters and environmental parameters were analysed with partial least squares regression. We used the available literature data to perform a regression analysis of liana biomass in response to elevation in humid tropical old‐growth forests between sea level and 3000 m a.s.l.ResultsLiana diameter, density and biomass all decrease with elevation. The decreasing liana biomass agrees with results from previous studies of liana biomass in other humid tropical forests, indicating a decrease of 0.18 Mg·ha−1 liana biomass per 100 m of elevation gain. Topographic variation leads to thinner but more abundant stems upslope; there was no effect of topographic position on liana biomass. Liana biomass and liana infestation are both positively correlated with host tree DBH at every elevation. Tree diameter growth is reduced by liana infestation; the proportion of infested trees is lower in Andean montane forests than in tropical lowland forests.ConclusionsLiana biomass distribution and tree infestation vary significantly with elevation. Biomass of lianas and relative contribution of lianas to total above‐ground biomass both decrease with elevation. Topographic effects likely result from higher soil fertility at lower slope positions.

Carbon storage and sequestration of re-growing montane forests in southern Ecuador

The storage and sequestration of carbon by tropical montane forests is poorly understood. We quantified the above-ground biomass (AGB) storage in secondary tropical montane forests in southern Ecuador. The AGB in older secondary (>40years old) forest was found to be 158±38Mgha−1 of land surface at 1000m elevation and 104±25Mgha−1 of land surface at 2250m elevation. This is less than the storage reported in a recent synthesis of AGB observations in mature tropical montane forests, potentially due to a legacy of selective logging within our study sites. The slope angle resulted in AGB being 1.5–10% greater when reported on a planimetric compared to land surface area basis. We also quantified AGB in areas of abandoned pasture where grazing and fire had been excluded. Pasture that had been recently abandoned (1–2years) stored 2–18Mgha−1 of AGB with the higher values due to the presence of relict trees. Re-growing secondary forests, established through natural regeneration, accumulated AGB at a rate of 10Mgha−1yr−1 at 1000m elevation and 4Mgha−1yr−1 at 2250m elevation, for the first 5–7years after pasture abandonment. After 12–15years, accumulation of AGB slowed to 1–2Mgha−1yr−1. Net biomass accumulation rates were similar to those observed in lowland humid tropical forests, suggesting that regenerating tropical montane forests provide an important carbon sequestration. In newly regenerating forests, small trees (DBH<10cm) contributed up to 50% of total AGB. In the older secondary forest at high elevation coarse dead wood contributed 34% of total AGB.

Soil N2O fluxes along an elevation gradient of tropical montane forests under experimental nitrogen and phosphorus addition

Nutrient deposition to tropical forests is increasing, which could affect soil fluxes of nitrous oxide (N2O), a powerful greenhouse gas. We assessed the effects of 35-56 months of moderate nitrogen (N) and phosphorus (P) additions on soil N2O fluxes and net soil N-cycling rates, and quantified the relative contributions of nitrification and denitrification to N2O fluxes. In 2008, a nutrient manipulation experiment was established along an elevation gradient (1000, 2000 and 3000 m) of montane forests in southern Ecuador. Treatments included control, N, P and N+P addition (with additions of 50 kg N ha−1 yr-1 and 10 kg P ha−1 yr-1). Nitrous oxide fluxes were measured using static, vented chambers and N cycling was determined using the buried bag method. Measurements showed that denitrification was the main N2O source at all elevations, but that annual N2O emissions from control plots were low, and decreased along the elevation gradient (0.57 ± 0.26 to 0.05 ± 0.04 kg N2O-N ha-1 yr-1). We attributed the low fluxes to our sites’ conservative soil N cycling as well as gaseous N losses possibly being dominated by N2. Contrary to the first 21 months of the experiment, N addition did not affect N2O fluxes during the 35-56 month period, possibly due to low soil moisture contents during this time. With P addition, N2O fluxes and mineral N concentrations decreased during Months 35-56, presumably because plant P limitations were alleviated, increasing plant N uptake. Nitrogen plus phosphorus addition showed similar trends to N addition, but less pronounced given the counteracting effects of P addition. The combined results from this study (Months 1-21 and 35-56) showed that effects of N and P addition on soil N2O fluxes were not linear with time of exposure, highlighting the importance of long-term studies.

Negative density dependence and environmental heterogeneity effects on tree ferns across succession in a tropical montane forest

Although tree ferns are an important component of temperate and tropical forests, very little is known about their ecology. Their peculiar biology (e.g., dispersal by spores and two-phase life cycle) makes it difficult to extrapolate current knowledge on the ecology of other tree species to tree ferns. In this paper, we studied the effects of negative density dependence (NDD) and environmental heterogeneity on populations of two abundant tree fern species, Cyathea caracasana and Alsophila engelii, and how these effects change across a successional gradient. Species patterns harbor information on processes such as competition that can be easily revealed using point pattern analysis techniques. However, its detection may be difficult due to the confounded effects of habitat heterogeneity. Here, we mapped three forest plots along a successional gradient in the montane forests of Southern Ecuador. We employed homogeneous and inhomogeneous K and pair correlation functions to quantify the change in the spatial pattern of different size classes and a case–control design to study associations between juvenile and adult tree ferns. Using spatial estimates of the biomass of four functional tree types (short- and long-lived pioneer, shade- and partial shade-tolerant) as covariates, we fitted heterogeneous Poisson models to the point pattern of juvenile and adult tree ferns and explored the existence of habitat dependencies on these patterns. Our study revealed NDD effects for C. caracasana and strong environmental filtering underlying the pattern of A. engelii. We found that adult and juvenile populations of both species responded differently to habitat heterogeneity and in most cases this heterogeneity was associated with the spatial distribution of biomass of the four functional tree types. These findings show the effectiveness of factoring out environmental heterogeneity to avoid confounding factors when studying NDD and demonstrate the usefulness of covariate maps derived from mapped communities.

A comparison of alpha and beta diversity patterns of ferns, bryophytes and macrolichens in tropical montane forests of southern Ecuador

We present a first comparison of patterns of alpha and beta diversity of ferns, mosses, liverworts and macrolichens in neotropical montane rainforests, and explore the question whether specific taxa may be used as surrogates for others. In three localities in southern Ecuador, we surveyed terrestrial and epiphytic species assemblages in ridge and slope forests in 28 plots of 400 m² each. The epiphytic habitat was significantly richer in ferns, liverworts, and macrolichens than the terrestrial habitat; mosses, however, were primarily terrestrial. Alpha diversity of ferns and of liverworts was congruent in both habitats. Mosses were similar to ferns and liverworts only in the epiphytic habitat. Macrolichens did not share patterns of alpha diversity with any other group. Beta diversity of ferns, mosses and liverworts (lichens excluded due to low species richness) was similar in the terrestrial habitat, but not in the epiphytic habitat. Our results demonstrate that patterns of alpha diversity of the studied taxa cannot be used to predict patterns of beta diversity. Moreover, diversity patterns observed in epiphytes are different from terrestrial plants. We noted a general coincidence in species patterns of liverworts and ferns. Diversity patterns of macrolichens, in contrast, were completely independent from any other taxonomic group studied.

Effects of environmental heterogeneity on species diversity and composition of terrestrial bryophyte assemblages in tropical montane forests of southern Ecuador

Background: Most studies on tropical bryophytes deal with epiphytic species. This is the first ecological study of tropical forests that focuses specifically on terrestrial bryophytes. Aim: To investigate the differences between slope and ridge environments in upper montane forests of southern Ecuador in terms of species diversity (richness, abundance), species composition and life forms of terrestrial bryophytes. Methods: We used Non-metric Multidimensional Scaling (NMDS) to group bryophyte relevés by study location, habitat type and exposure class. Species indicator values were calculated and compared for different habitats. Results: In total, 140 species were recorded, the majority being liverworts. NMDS analyses and Mantel correlations clearly separated between slope and ridge relevés, and between sunny and shaded microhabitats on ridges. Bryophyte life forms also showed different distribution patterns in slope and in ridge habitats. Mosses were more prominent in sunny than in shaded microhabitats. Conclusions: Environmental differentiation between ridges and slopes, and small-scale variation in microclimatic conditions caused by differences in exposure, were stronger predictors of species richness and composition than geographical distance between study sites.

Tree phenology in montane forests of southern Ecuador can be explained by precipitation, radiation and photoperiodic control

Abstract:We investigated the effect of seasonality on tree phenology in the tropical montane rain forest of southern Ecuador and analysed possible triggering factors. Two hypotheses were tested: (1) Interspecific synchronization of flowering and fruiting phenology is higher at study sites with pronounced rainfall seasonality compared with sites within perhumid forests. (2) Proximate causes for flowering in closely situated seasonal and perhumid sites are either photoperiodicity or climatic factors. Two nearby study sites with contrasting precipitation patterns were selected at the same altitude east and west of the western Cordillera. Eighty trees from 13 species were observed over a 2.5-y period. Three species were common to both study sites. Phenological and climate data were collected and cross-correlated by conducting a time-series analysis. At the perhumid site, very clear annual patterns of phenological behaviour could be observed for most of the selected rain-forest tree species, but with a poor interspecific synchronization. On the nearby seasonal site in contrast, most species showed high synchrony in their phenological behaviour coinciding with the dry season. There is strong evidence that flowering is induced not by one factor alone: we identified photoperiodic control, radiation and precipitation as possible proximate causes for both sites. Our results confirm studies which state that these factors are closely linked to each other in the tropics.

Above- and below-ground litter production in three tropical montane forests in southern Ecuador

Litter production from above-ground (leaves, twigs, fruits, flowers) and below-ground (roots) plant organs is an important component of the cycling of carbon and nutrients in forests. Tropical montane forests possess comparatively large quantities of fine-root biomass, suggesting that litter production by dying fine roots may represent a major component of total litter production. In a comparative study in three tropical montane forests of southern Ecuador at 1890, 2380 and 3060 m elevation, we measured leaf-fall by litter trapping and fine-root litter production by sequential soil coring and fine-root biomass and necromass analysis for about 1 y with the objectives (1) to quantify annual above- and below-ground litter production, and (2) to investigate elevational differences in litter production. Leaf litter mass decreased to less than a third (862 to 263 g m−2 y−1) with increasing elevation (1890 m to 3060 m), whereas fine-root litter production increased by a factor of about four (506 to 2084 g m−2 y−1). Thus, the ratio of leaf to fine-root litter shifted by an order of magnitude in favour of fine-root litter production between 1890 to 3060 m. Fine-root litter production was not synchronized with leaf litterfall and was seasonal only at 3060 m with mortality peaks in the drier and the wetter periods. We conclude that dying fine roots represent a very important fraction of total litterfall in tropical montane forests that can exceed the quantity of leaf litter. At 3060 m, the largest part of the organic material on top of the soil must originate from dying fine roots but not from fallen leaves.

Arbuscular endomycorrhizas are dominant in the organic soil of a neotropical montane cloud forest

The ecology and forest management of tropical montane cloud forests of the Neotropics have attracted little scientific attention so far, and understanding of the ecosystem is still fragmentary (Churchill et al. 1995). The montane forests of southern Ecuador are an outstanding biodiversity hotspot for vascular plants (Barthlott et al. 1996), including a multitude of tree species (Madsen &amp; Øllgard 1994). However, identification of species, studies of phenology, productivity, seed production and growth of seedlings have only just begun (Homeier &amp; Breckle 2002). None of the trees has been investigated with respect to their mycorrhizal status, although it is well established that mycorrhizal symbioses are not only important for survival of trees in nutrient-poor habitats (Read 1991) and play a key role for nutrient cycling and nutrient retention in the humus layers (Medina &amp; Cuevas 1993, Rilling et al. 2001), but also have an important impact on the composition of plant communities (Allen et al. 1995, Kottke 2002, van der Heijden et al. 1998).

Passiflora brachyantha (Passifloraceae), a New Species from the Andes of Southern Ecuador

A new species of Passifora subg. Tacsonia is described from the Andes of southern Ecuador. Passiflora brachyantha is placed in section Bracteogama, where it most closely resembles another short-flowered species, P. glaberrima, which is endemic to Peru. Members of Passifora subg. Tacsonia (A. L. Juss.) Triana & Planchon, are tendriled lianas confined to high Andean habitats, distributed from the Cordillera de Merida in northwestern Venezuela to Bolivia. One cultivated species, Passiflora pinnatistipula Cav., is found in mesic sites in the Andes of Chile. The plants are characterized by long-tubed, highly colored, hummingbird-visited flowers, and the geographical distribution of the plants coincides with that of Ensifera ensifera, the sword-billed hummingbird (Escobar, 1980, 1989b; Schauensee, 1982). Hypanthium length in the subgenus varies, however, and falls mainly into two groups: (1) longtubed species probably pollinated by Ensifera ensifera, as is the most widespread species, Passifora mixta L. f. (Snow & Snow, 1980), and (2) shortertubed species presumably pollinated by shorter-billed hummingbirds. There are few species of intermediate hypanthium length (Escobar, 1980). Since all of the subgenera of Passifiora that are confined to the high Andes produce flowers adapted for hummingbird pollination (Escobar, 1989b, and unpublished data), it is likely that the short-tubed taxa, which are most common in southern Ecuador and northern Peru, have speciated in response to the selective pressures exerted by their pollinators. Section Bracteogama (DC.) L. Escobar comprises 14 of the 47 species placed by Escobar in subgenus Tacsonia (Escobar, 1980, 1987, 1988, 1989a) and has its center of diversity in the moist montane forests of southern Ecuador and the eastern Andean slopes of northern Peru around the Huacabamba depression. The members of the section are recognized by the presence of large, coriaceous, mostly connate bracts that enclose and presumably protect the bud during development (Escobar, 1980; Harms, 1925). Both long-flowered and short-flowNOVON 2: 198-200. 1992. ered species occur in this section. The new species described here is another short-flowered member of section Bracteogama. Passiflora brachyantha L. Escobar, sp. nov. TYPE: Ecuador. Loja: 8 km W of Loja on road to Catacocha, 7,400 ft., 30 Jan. 1979 (fl, fr), R. M. King & F. Almeda 7887 (holotype, US). Figure 1. Differt a Passiflora glaberrima (A. L. Juss.) Poiret caulibus foliis bracteisque pubescentibus, foliis majoribus apicibus acuminatis, et floribus roseis. Lianas with stout tendrils, pubescent on stems, petioles, peduncles, bracts, and abaxial surface of leaves and stipules, with straight to wavy, transparent trichomes to 0.5 mm long. Stems angulate, striate. Leaf blades 3-lobed, 3.5-7.3 cm long, 7.811.0 cm wide, parted ca. 34 their length into 3 elliptic segments, acuminate at apex of lobes, shallowly cordate at base, glandular-serrate at margins, coriaceous; lateral segments 2.2-5.5 cm long, 1.63.4 cm wide, divergent from mid-segments ca. 90?; mid-segments 3.5-7.3 cm long, 1.6-3.3 cm wide; petioles 1.2-2.7 cm long, with 3-5 subspherical nectaries 0.7-1.2 mm long, 0.8-1.0 mm wide, scatt red on upper half of adaxial surface; stipules reniform, concave, 1.2-1.5 cm long, ca. 6 mm wide, attenuate at apex, oblique at base, shallowly glandular-serrulate at margins, coriaceous, glabrous on adaxial surface. Peduncles slender, 2.7-3.4 cm long, bearing pendent flowers; bracts oblong, connate ca. 34 their length from base, forming an ampliate tube at base of hypanthium, each bract 3.1-3.5 cm long, 1.0-1.1 cm wide, acuminate at apex. Flowers 6.46.8 cm long, ca. 3.5 cm wide, bright pink; hypanthium 3.9-4.0 cm long, 0.4-0.6 cm wide (pressed), dilated at base, pubescent on outer surface with straight, transparent trichomes ca. 0.3 mm long; sepals oblong, ca. 2 cm long, ca. 0.6 cm wide, pubescent with subterminal aristae ca. 1 mm long on abaxial surface; petals subequal to sepals; corona tuberculate, ca. 0.3 mm long; ovary ellipsoidal, pubescent with fine, straight trichomes ca. 0.1 mm This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 06:16:24 UTC All use subject to http://about.jstor.org/terms Volume 2, Number 3 1992 199 Escobar Passiflora brachyantha