Environmental changes in biodiversity hotspot ecosystems of
South Ecuador: RESPonse and feedback effECTs (FOR2730)

Abstract:

Andean mountain rainforests rank among the most diverse ecosystems of the world. Especially for insects these biomes serve as a hotspot. It is still little known about how the extremely species-rich group of moths react to gentle intrusions on naturally grown forests. The research area of this project (Reserva Biológica San Francisco) is located at the border of the Podocarpus National park in South Ecuador. The research was carried out with moths of the species-rich group of the Arctiidae family, which were collected at 9 sampling sites in ravine forests. Three sampling sites were situated in a branch of a valley with the original undisturbed vegetation, 3 in a branch with lightly disturbed forest vegetation and 3 in a branch with stronger forestral intrusions. The group of Arctiidae were collected in a period of time between 15.02.2005 and 17.05.2005 using light-traps, that is to say 8-11 month after the completion of the forestral experiment. Light-trapping was carried out at the 9 sampling sites between 19:00 and 22:00 local time using a light trap (with both a 15 W ultra-violet-tube and a normal tube). In 28 nights of sampling 1.054 individuals related to 140 species were caught. For the final analysis these data were combined with earlier light-trapping data resulting from sampling amongst 4 other habitat types also ranging in elevation from 1.800 m to 2.000 m above sea level (early and late states of succession, open grassland and ridge forest). In consideration of the abundances of the Arctiidae the 9 locations did not differ from each other nor did the 3 quebradas of the ravine forest. In the ridge forest, the ravine forest and the open grassland far less individuals were collected compared to the succession habitats. The local diversity of the butterfly communities in the ravine forest was not as pronounced as compared to the ridge forest but this might have been caused by seasonal differences and/or the relatively small sample sizes. The samples of the Arctiidae at all 30 sampling sites were ordained within multidimensional scaling, underlying the CNESS index with the different values of the sampling-parameter m. Thereby a clear segregation of the ravine forest-sites from the ridge forest and the succession-habitats became obvious. The differences between the arctiid faunas became more apparent, if the moderate frequent species were given more weight in the analysis (m = 9-12). Matrix-rank-correlation-tests with different environmental parameters showed an apparent coherency of the differences in arctiid fauna with the degree of the opening of the crowns (visible sky). Whereas the spatial nearness of the sampling sites to each other did not show any correlation. The effects of the forestral experiments on the arctiid communities first became apparent when regarding the data from moths collected during the rain period. The community of species of the undisturbed quebrada Q2 clearly differs from the more or less disturbed quebradas. However they do not differ from the structure of the community of the ridge forest. Thus ? disregarding seasonal effects ? the nature forest understorey and ravine forest in the research area do not clearly differ in their fauna. Between the quebradas with different forestral treatments there was no difference in the variety and composition of the species? communities. Abundant species in the disturbed quebrada-forests were Amastus coccinator (2,5%), Areva albogrisea (13%), Melese endopyra (4%) and Napata sp.3 (3,4%). The sites of the closed nature forest understorey are especially favoured by many monophageous species of the tribe Ctenuchini, whereas in the disturbed habitats sturdy species with stronger flying abilities can be found. The results of this study show that already small-scale intrusions limited in time on the natural vegetation can cause a significant change in the composition of arctiid communities. At the same time no difference in the impact of the degree of forestral intrusions could be proved.

Abstract:

The genus Eois (Larentiinae) comprises an important part of a megadiverse assemblage of geometrid moths in the mountain rainforests of southern Ecuador. Owing to the diversity of morphotypes found in this genus, the abundance of many of its component species, and the close relationships with larval food plants in the genus Piper, the genus Eois was chosen as a target for more detailed investigation on the suitability of DNA barcode applications and phylogenetic relationships. COI barcode sequences (676 bp) were generated from 342 individuals to establish an inventory of DNA barcodes from one study area (Reserva Biológica San Francisco). This inventory can be used to match larvae to known adult samples without rearing, and will therefore be of vital help to extend the currently very limited knowledge about food plant relationships and host specialization. Analyses of barcoding sequence divergence showed that species delimitations based on external morphology alone result in broad overlap of intra- and interspecific distances. Species delimitation at a 3% pairwise genetic distance threshold eliminated all but 3 out of 9 cases causing overlap and delimitation at a 2% threshold resulted in a clear barcoding gap. 30 previously unrecognized species were identified solely on morphological evidence, and their species status was subsequently supported by barcode sequence data. In addition to that 9 putative species could be recognized by threshold based delimitation. Hence, the present study increased the number of Eois species recorded from that small area of Andean mountain forests from 99 to 129 (morphology-based) or even 138 (sequence-based). Notably there are no cases where two or more previously known morphospecies had to be lumped. We acquired elongation factor 1-alpha sequences and extended COI sequences of 102 individuals amounting to a combined sequence dataset of ~2200 bp. These represented at least 70 Eois species plus a range of outgroup taxa. Maximum parsimony and Bayesian inference of phylogeny were employed to estimate relationships within Eois. Monophyly of Eois was always strongly supported. Phylogenetic trees revealed that all included wingpattern types except for one evolved only once. The exception to this rule occurred in the most basal clade whose species closely resemble those in a clade higher up in the tree. This may represent an ancestral character state or the result of convergent evolution. Additionally it could be determined that species known to feed on Piper are spread over most of the major clades within Eois, indicating that the host plant relationship with Piper is indeed a widespread trait among the Neotropical members of the genus and not just occurs in certain subclades. The number of species and individuals recorded from Piper is however skewed towards two subclades. Within the subfamily Larentiinae the genus Eois has traditionally been placed close to the tribe Eupitheciini, but there is presently no support for such a placement in our phylogenetic analyses.

Abstract:

Long-term field studies in the scope of a multidisciplinary project in southern Ecuador revealed extraordinary high species numbers of many organismic groups. This article discusses reasons for the outstanding vascular plant diversity using a hierarchical scale-oriented top-down approach (Grüninger 2005), from the global scale to the local microscale. The global scale explains general (paleo-) ecological factors valid for most parts of the humid tropics, addressing various hypotheses and theories, such as the ?greater effective evolutionary time?, constant input of ?accidentals?, the ?seasonal variability hypothesis?, the ?intermediate disturbance hypothesis?, and the impact of soil fertility. The macroscale focuses on the Andes in northwestern South America. The tropical Andes are characterised by many taxa of restricted range which is particularly true for the Amotape-Huancabamba region, i.e. the so called Andean Depression, which is effective as discrete phytogeographic transition as well as barrier zone. Interdigitation of northern and southern flora elements, habitat fragmentation, geological and landscape history, and a high speciation rate due to rapid genetic radiation of some taxa contribute to a high degree of diversification. The mesoscale deals with the special environmental features of the eastern mountain range, the Cordillera Real and surrounding areas in southern Ecuador. Various climatic characteristics, the orographic heterogeneity, the geologic and edaphic conditions as well as human impact are the most prominent factors augmenting plant species diversity. On microscale, prevailing regimes of disturbance and environmental stresses, the orographic basement, as well as the general role on the various mountain chains are considered. Here, micro-habitats e.g. niches for epiphytes, effects of micro-relief patterns, and successions after small-sized disturbance events are screened. Direct effects of human impact are addressed and a perspective of possible effects of climate change on plant diversity is presented.

Abstract:

Ref.: Ms. No. EJFOR-D-08-00181R1 accepted on 16-06-2009 Ecosystem analysis is typically done by determination of species composition, structural ex-ploration, determination of matter and energy fluxes and/or system analyses based on deter-ministic or probabilistic/stochastic model approaches. However, regarding ecosystem dynam-ics, temporal structure, information content, complexity of signals, and their modifications when subsequently passing through different subsystems, have not intensively been studied to date. Structure in time series characterised by information and complexity measures may pro-vide additional, powerful tools to analyse state and dynamics of ecosystems. Along their path through ecosystem compartments e.g. hydrological signals are transformed in several ways, comprising changes in randomness, autocorrelation structures, and smoothness. Thus, time series analyses with complexity and information measures is of interest for a holistic under-standing of ecosystem behaviour and early indications of natural and anthropogenic distur-bances of ecosystems like ecosystem degradation and climate change. Further, these measures provide additional criteria for the calibration of model parameters tests of model validity, and determination of the necessary degree of complexity of process models. In this paper we pre-sent the outcome from applications of information and complexity measures to hydrological time series in two climatically different forest ecosystems in South Germany and Southern Ecuador. The values of information and complexity measures have a clearly different range for the different hydrological parameters but for ecosystems of the same type like mountain forest the values of information and complexity measures exhibit similar behaviour for the hydrological parameters. We hypothesize that complexity of hydrological time series in-creases with the number of abiotic and biotic variables involved in the generating process of the time series. Thus, complexity should have a minimum in the precipitation signal which is controlled by abiotic, atmospheric factors only, and reach a maximum in the root zone where the interaction of abiotic and biotic variables is high. Hydrological time series under study cover the sequence of hydrological signals from open precipitation, throughfall, sapflow, wa-ter fluxes in the soil compartment and system discharge. We detected pronounced data aggre-gation and transformation effects of hydrological signals along their path through subsystems in terms of information propagation. We further found similar patterns in different ecosystems of the same general type. As a result of intensive abiotic and biotic interactions, a pronounced maximum of complexity was found in the moisture signal of the soil compartment.

Abstract:

A new species of mountain viscacha, Lagidium ahuacaense, is described based on a specimen and a mitochondrial cytochrome b (cyt b) sequence obtained from a second individual from Cerro El Ahuaca, Loja Province, Ecuador. In several external and craniodental measurements, the new species differed significantly from the three congeneric species (greatest length of skull, basilar, nasal length, palatilar length, length of diastema, least interorbital breadth, breadth of rostrum and skull height). The cyt b sequence of the Ecuadorean viscacha differed by 14 exclusive nucleotide substitutions from all other sequences of Lagidium examined. Kimura 2-parameter (K2P) genetic distances of the Ecuadorean sequence were 8.1?11.0% to L. peruanum, 7.9?9.9% to L. viscacia and 9.7% to L. wolffsohni. The single known population of the newly described species may not comprise more than a few dozen individuals and warrants urgent conservation actions.

Abstract:

While tropical deforestation proceeds at high pace, conservation biologists remain divided over the extent to which anthropogenic habitats will be able to offset the loss of biodiversity from primary forests. Case studies addressing disturbance effects on epiphyte assemblages have yielded contrasting patterns, and underlying mechanisms remain unclear. At present, one of the questions most widely debated is the importance of growth conditions vs. dispersal limitations for the persistence of epiphyte populations following disturbance. The present dissertation aims at contributing to our understanding of the processes that determine epiphyte diversity in anthropogenic landscapes, focussing primarily on assemblages of vascular epiphytes on isolated trees. Isolated trees offer an excellent model system since they constitute the smallest possible forest fragment, exposed to multiple edge effects and dispersal limitations. Field work was done from 2003?2006 at two lower montane sites in the Ecuadorean Andes: (1) moist forest (2200 mm rain/yr; 1800?2200 m elevation) and adjacent matrix habitat around Estación Científica San Francisco (ECSF) on the eastern Andean slope (Zamora-Chinchipe Province), and (2) perarid Interandean forest (530 mm rain/yr; 2300m elevation) and adjacent pastures at Bosque Protector Jerusalén (Pichincha Province). At the moist forest site (ECSF), I studied the diversity of vascular epiphytes on remnant trees ca. 10?30 years after their isolation in pastures (chapter 2). The objective of this study was to document the importance of remnant trees for the survival of vascular epiphyte communities following forest clearance. Trees were divided into five zones following Johansson (1974) and climbed with the single rope technique. Abundance and diversity of epiphytes were significantly lower on remnant trees than on forest trees. Several families rich in xerophilous taxa (Bromeliaceae, Orchidaceae, Piperaceae, Polypodiaceae) were relatively well represented on remnant trees in terms of species richness and abundance, whereas essentially hygrophilous families such as Dryopteridaceae, Ericaceae, Grammitidaceae and Hymenophyllaceae were poorly represented or absent. Impoverishment was greatest on the stem base and in the outer crown, and least in the inner crown of the host trees. These results suggest that the observed impoverishment on isolated trees is closely related to microclimatic changes. Experimental work done at the same site gave some insight into the mechanisms behind the pronounced impoverishment of epiphyte assemblages. In one field trial (chapter 6) I studied abundance, diversity and floristic composition of epiphyte seedling establishment on isolated and adjacent forest trees. All vascular epiphytes were removed from plots on the trunk bases of a common tree species (Piptocoma discolor). Newly-established epiphyte seedlings were recorded after two years, and their survival after another year. Seedling density and the number of taxa (families and genera, respectively) per plot were significantly reduced on isolated trees relative to forest trees, as was the rarefied total number of epiphyte taxa. Seedling assemblages on trunks of forest trees were dominated by hygrophilous understorey ferns whereas assemblages on isolated trees were dominated by xerophilous canopy taxa. Colonisation probability was significantly higher for plots closer to forest but not for plots with greater canopy or bryophyte cover. Seedling mortality on isolated trees was significantly higher for hygrophilous than for xerophilous taxa. These results show that altered recruitment can explain the long-term impoverishment of post-juvenile epiphyte assemblages on isolated remnant trees. Altered establishment is attributed to a combination of dispersal constraints and the changed microclimate that was documented by measurements of temperature and humidity. Although isolated trees in anthropogenic landscapes are key structures for the maintenance of forest biodiversity in many aspects, my results show that their value for the conservation of epiphyte diversity can be limited. Abiotic seedling requirements may increasingly constitute a bottleneck for the persistence of vascular epiphytes in the face of ongoing habitat alteration and atmospheric warming. In a second field trial at the same site (chapter 7) I studied the response of assemblages of well-established vascular epiphytes to severe forest disturbance. Individual plants were marked on isolated remnant trees (up to 5 m above ground) in a fresh clearing and in undisturbed forest (controls), and their growth and survival was followed during three consecutive years. Wind-throw and branch breakage caused the loss of 24% of plants from isolated trees but only of < 1% in the forest. Epiphyte mortality on the remaining, intact phorophytes was substantially higher on remnant trees than on forest trees, averaging 72% vs. 11% after 3 years. Mortality on isolated trees was greatest after the first year (52%) and among ferns and dicots, and lowest after the second year (20%) and among monocots (aroids, bromeliads, orchids). Mortality differed significantly between taxa but was elevated significantly for most taxa after the first year relative to forest levels. Plants that survived on isolated trees commonly showed a marked decrease in maximum leaf length. The annual increment in leaf number varied more widely, both between and within epiphyte families. This study provides first experimental, field-based evidence that increased physical exposure affects the performance of well-established vascular epiphytes. The results suggest that growth conditions may often be a more influential driver of vascular epiphyte diversity in disturbed habitats than dispersal. It is argued that elevated desiccation stress is only one of several mechanisms by which increased physical exposure may limit epiphyte performance in disturbed habitats. The two trials showed that the marked impoverishment of vascular epiphyte assemblages at the study site results from both lowered recruitment and survival of established plants, and that mid-term effects of changes in growth conditions can be drastic. At the dry forest site (Bosque Protector Jerusalén) I studied the development of epiphyte diversity and abundance across a disturbance gradient (chapters 3 and 4). Epiphytic bryophytes and vascular plants were sampled on 100 trees of the dominant tree species, Acacia macracantha, in five habitats: closed-canopy mixed and pure acacia forest (old secondary), forest edge, young semi-closed secondary woodland, and isolated trees in grasslands. Host trees were divided into four zones (cf. Johansson 1974). Species density and surface cover of vascular epiphytes were determined for each zone, bryophytes were only sampled in the inner crown. Total species richness in forest edge and on isolated trees was significantly lower than in closed forest types. Species density of vascular epiphytes did not differ significantly between habitat types. Species density of bryophytes, in contrast, was significantly lower in forest edge and on isolated trees than in closed forest. Surprisingly, edge habitat showed greater impoverishment than semi-closed woodland and similar floristic affinity to isolated trees and to closed forest types. Assemblages were significantly nested; habitat types with major disturbance held only subsets of the closed forest assemblages, indicating a gradual reduction in niche availability. This conclusion is lent further support by patterns of epiphyte abundance. Bromeliads were xerophilous and early-successional, being most abundant in the middle crown, whereas ferns were skiophilous and late-successional, being essentially restricted to the inner crown. While the former were significantly more abundant on isolated trees than in closed forest, the latter were restricted to closed forest and semi-closed woodland. Bryophyte cover was significantly lower on isolated trees and in forest edge than in closed forest. Total species density and covers of epiphytes on isolated trees were not related to the distance to forest, but total species density and bryophyte cover were closely correlated with crown closure as a measure of canopy integrity. These results suggest that microclimatic changes are key determinants of the observed impoverishment of epiphyte assemblages following disturbance, and that epiphytic cryptogams are sensitive indicators of microclimate and human disturbance in montane dry forests. Patterns of abundance and diversity further suggest that the ?similar gradient hypothesis? (McCune 1993) applies to tropical dry forest assemblages of epiphytes. The substantial impoverishment of edge habitat underlines the need for fragmentation studies on epiphytes elsewhere in the Tropics. Case studies on vascular epiphyte assemblages have failed to find a common, general response to human disturbance. In chapter 5, a hypothesis is proposed and explored that aims to explain and unite these conflicting patterns in the light of a non-linear effect of local climate: while the diverse assemblages of moist, slightly seasonal forests rely on the integrity of forest canopies during droughts, this dependency may be less pronounced in aseasonally wet or distinctly dry forests. This hypothesis is supported by the results of a literature survey.

Abstract:

The organic layer of evergreen tropical mountain forests plays a constitutive role concerning the water balance in these ecosystems. Knowledge of the hydraulic conductivity function and the water retention function permits the description of this water balance by application of the Richards equation (Richards, 1931) for liquid flow in unsaturated porous media. For this purpose ten samples of the organic layer, taken in a mature tropical mountain forest in South Ecuador, were collected and treated in laboratory multi-step irrigation experiments. By applying inverse modelling techniques on the observed drainage data, the soil hydraulic Mualem-van-Genuchten parameters were derived, using three different model approaches (van Genuchten, 1980; Durner et al., 1999; ?im&#367;nek et al., 2003). Calculations of the Richards equation based on these parametersets were congruent with the observed drainage hydrographs. The estimated parameters showed only low variation in case of the Mualem-van-Genuchten model (van Genuchten, 1980), whereas for the two dual-porosity models (Durner et al., 1999; ?im&#367;nek et al., 2003) some parameters scattered considerably. Problems concerning nonunique solutions were assessed by dint of response-surface analysis as well as a sensitivity study of variations in the initial parametersets. It became clear that the observed drainage hydrograph may be explained by multiple different parametersets. Thus, a physical interpretation of the optimized parameters must be neglected. Simulations run both on optimized parametersets and parametersets averaged over all samples were cross-validated against alternative irrigation experiments. Each model was able to predict the observed drainage hydrograph well. Shifts with increasing irrigation rates were problematic, which can be explained by hysteresis effects. In this range best predictions were achieved by the dual-porosity model proposed by ?im&#367;nek et al. (2003). However, this model lacks accuracy in regions of high irrigation rates and large steps between irrigation rates, where the other models presented in this work perform better. For the purpose of simulating water flow at this site it is proposed to use the averaged parameterset of the Mualem van Genuchten model, since it is distinguished by an acceptable simulation power but low parametrization.