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

Abstract:

The water budget of forested catchments controls the local water supply and influences the regional climate. To assess anthropogenic impact on the water cycle we constructed a water budget for three ~10 ha catchments under lower montane forest on the east-facing slope of the Andes in south Ecuador at 1900-2150 m elevation. We used field hydrological measurements and modeled surface flows with TOPMODEL, a semi-distributed catchment model. We measured incident precipitation, throughfall, stemflow, and surface flow between May 1998 and April 2002 in hourly to weekly resolution, and determined all variables needed to parameterize TOPMODEL. On average of the four monitored years and three catchments, incident precipitation was 2504±s.d.123 mm, throughfall 1473±197 mm, and stemflow 25±2 mm yr-1. Fog water input was negligible. Mean annual interception loss in the forest was 1006±270 mm, and mean annual surface flow, calculated with TOPMODEL in an hourly resolution was 1039±48 mm. The resulting mean annual evapotranspiration was 1466±161 mm of which 32% (=471±162 mm) was transpiration if evaporation from the soil was neglected. Our study catchments show a high evapotranspiration attributable to the strong solar insolation near the equator, the small impact of fog, the generally low intensity of incident precipitation and additional wind-driven advective energy input.

Abstract:

SIR ? Your Editorial ?Markets can save forests? proposes integrating deforestation into the international carbon market (Nature 452, 127?128; 2008), but it is unlikely that money alone can solve the problem. The process of tropical deforestation presents a dilemma: enormous economic value more than US$ 2,000 a year per hectare is lost in favour of small private benefits (often less than US$ 100 a year per hectare). In a true market, an increased, scarcity-signalling price should provide an incentive to boost the supply of the scarce commodity. So far, this has not worked in the case of tropical forests. Real financial flows received for the provision of ecosystem services are vanishingly small, if they exist at all ? only a few beneficiaries have been convinced to pay for environmental services. This illustrates the essentially theoretical character (at least, up till now) of economic values generated by ecosystem services. Payments for ecosystem services (PES) are supposed to save tropical forests. But even if it were possible to mobilize substantial PES, tropical farmers wouldn?t be prepared to stand by and twiddle their thumbs while receiving these payments to protect the forest. They need a field of activity, so sustainable land-use concepts should address the social environment and needs of people as well. These concepts could be linked and possibly financed by PES. If the people who use tropical lands are disregarded, we don?t believe that PES will solve the problem of disappearing tropical forests. What is needed is an economic system that keeps people gainfully employed in an activity that is ultimately productive, not destructive.

Abstract:

In forests, complex canopy processes control the change in volume and chemical composition of rain water. We hypothesize that (i) spatial patterns, (ii) the temporal stability of spatial patterns, and (iii) the temporal course of solute concentrations can be used to explore these processes. The study area at 1950 m above sea level in the south Ecuadorian Andes is far away from anthropogenic emission sources and marine influences. It received ca. 2200 mm of rain annually. We collected rain and throughfall on an event and within-event basis for five precipitation periods between August and October 2005 at up to 25 sites and analyzed the samples for pH and concentrations of , , , , , , , , and total N ( ), P ( ), and organic C ( ). Cumulative throughfall amounted to 79% of rainfall. Compared with other tropical forests, rainfall solute concentrations were low and throughfall solute concentrations similar. Volumes and solute concentrations of rainfall were spatially and temporally little variable. The spatial coefficient of variation for throughfall volumes was 53%, for solute concentrations 28–292%, and for deposition 33–252%. Temporal persistence of spatial patterns was high for throughfall volumes and varied among solutes. Spatial patterns of , and concentrations in throughfall were highly persistent. The spatial patterns of throughfall fluxes were less stable than those of concentrations. During a monitoring time of 72 hours, solute concentrations in throughfall of selected rain events remained at a similar level indicating that the leachable element pool in the canopy was not exhausted. Our results demonstrate that the passage of rain through the canopy of a tropical montane forest in Ecuador results in a spatially heterogeneous throughfall pattern with a considerable stability during three months. There is a large leachable element pool in the canopy, which is not depleted by the typical light rain within 72 hours.

Abstract:

In tropical montane forests, soil properties change with altitude and tree growth decreases. In a tropical montane forest in Ecuador, we determined soil and tree properties along an altitudinal transect between 1960 and 2450 m above seal level. In different vegetation units height, basal area, and diameter growth of trees were recorded, and all horizons of three replicate profiles at each of eight sites were sampled. We determined pH and total concentrations of Al, C, Ca, K, Mg, Mn, N, Na, P, S, Zn, polyphenols, and lignin in all soil horizons and in the mineral soil additionally the effective cation-exchange capacity (ECEC). The soils were Cambisols, Planosols, and Histosols. The concentrations of Mg, Mn, N, P, and S in the O horizons and of Al, C, and all nutrients except Ca in the A horizons correlated significantly negatively with altitude. The C/N, C/P, and C/S ratios increased and the lignin concentrations decreased in O and A horizons with increasing altitude. Forest stature, tree basal area, and tree growth decreased with altitude. An ANOVA analysis indicated that macronutrients (e.g., N, P, Ca) and micronutrients (e.g., Mn) in the organic layer and in the soil mineral A horizon were correlated with tree growth. Furthermore, lignin concentrations in the organic layer and the C/N ratio in soil affected tree growth. These effects were consistent, even if the effect of altitude was accounted for in a statistical hierarchical model. This suggests a contribution of nutrient deficiencies to reduced tree growth possibly caused by reduced organic matter turnover at higher altitudes.

Abstract:

[1] We quantified base metal deposition to Amazonian montane rainforest in Ecuador between May 1998 and April 2003 and assessed the response of the base metal budget of three forested microcatchments (8-13 ha). There was a strong interannual variation in deposition of Ca [4.4-29 kg ha-1 yr-1], Mg [1.6-12], and K [9.8-30]). High deposition changed the Ca and Mg budgets of the catchments from loss to retention, suggesting that the additionally available Ca and Mg was used by the ecosystem. Increased base metal deposition was related to dust outbursts of the Sahara and an Amazonian precipitation pattern with trans-regional dry spells allowing for dust transport to the Andes. The increased base metal deposition coincided with a strong La Niña event in 1999/2000.

Abstract:

In order to study the stability and dynamics of mountain rainforest and paramo ecosystems, including the biodiversity of these ecosystems, the Holocene and late Pleistocene climate and fire variability, and human impact in the southeastern Ecuadorian Andes, we present a high-resolution pollen record from El Tiro Pass (2810m elevation), Podocarpus National Park. Palaeoenvironmental changes, investigated by pollen, spores and charcoal analysis, inferred from a 127cm long core spanning the last ca. 21 000 cal. yr BP, indicate that grass-paramo was the main vegetation type at the El Tiro Pass during the late Pleistocene period. The grass-paramo was rich in Poaceae, Plantago rigida and Plantago australis, reflecting cold and moist climatic conditions. During the early Holocene, from 11200 to 8900 cal. yr BP, subparamo and upper mountain rainforest vegetation expanded slightly, indicating a slow warming of climatic conditions during this period. From 8900 to 3300 cal. yr BP an upper mountain rainforest developed at the study site, indicated by an increase in Hedyosmum, Podocarpaceae, Myrsine and Ilex. This suggests a warmer climate than the present day at this elevation. The modern subparamo vegetation became established since 3300 cal.yr BP at El Tiro Pass. Fires, probably anthropogenic origin, were very rare during the late Pleistocene but became frequent after 8000 cal. yr BP.

Abstract:

Two data sets representing atmospheric moisture are available for the high Andes of Ecuador, (i) cloud frequency obtained from weather satellites, and (ii) interpolated rainfall estimates obtained from global climate observations. We analyzed their correlation to vascular plant species composition at 18 Ecuadorian superpa´ ramo study sites. Of particular interest was whether cloud frequency could be used as a proxy for precipitation. Cloud frequency had distinct seasonal and spatial variation among the sites. The spatial gradient of cloudiness was strongest during June–August and weakest around the equinoctials. Interpolated rainfall estimates also showed seasonal and spatial variation among the sites, but there was no correlation between them and cloudiness. Cloud frequency during June–August was the only significant variable in the canonical correspondence analysis (CCA) of the species composition, whereas rainfall estimates, geology, presence of glaciers, and size and altitudinal range of the superpa´ ramos were not significant. When the spatial components were filtered out from the species composition data by employing partial CCA, cloud frequency during December–February became the only significant variable. Our results suggest that cloud frequency data may be a useful tool in mountain ecology research, serving as an indicator of habitat humidity when exact precipitation data are lacking.

Abstract:

Mycorrhizas of vascular plants and mycorrhiza-like associations of liverworts and hornworts are integral parts of terrestrial ecosystems, but have rarely been studied in tropical mountain rain forests. The tropical mountain rain forest area of the Reserva Biológica San Francisco in South Ecuador situated on the eastern slope of the Cordillera El Consuelo is exceptionally rich in tree species, ericads and orchids, but also in liverworts. Previous light and electron microscopical studies revealed that tree roots are well colonized by structurally diverse Glomeromycota, and that epiphytic, pleurothallid orchids form mycorrhizas with members of the Tulasnellales and the Sebacinales (Basidiomycota). Sebacinales also occurred in mycorrhizas of hemiepiphytic ericads and Tulasnellas were found in liverworts belonging to the Aneuraceae. On the basis of these findings we hypothesized that symbiotic fungi with a broad host range created shared guilds or even fungal networks between different plant species and plant families. To test this hypothesis, molecular phylogenetic studies of the fungi associated with roots and thalli were carried out using sequences of the nuclear rDNA coding for the small subunit rRNA (nucSSU) of Glomeromycota and the large subunit rRNA (nucLSU) of Basidiomycota. Sequence analyses showed that Sebacinales and Tulasnellas were only shared within but not between ericads and orchids or between liverworts and orchids, respectively. Regarding arbuscular mycorrhiza forming trees, however, 18 out of 33 Glomus sequence types were shared by two to four tree species belonging to distinct families. Nearly all investigated trees shared one sequence type with another tree individual. Host range and potential shared guilds appeared to be restricted to the plant family level for Basidiomycota, but were covering diverse plant families in case of Glomeromycota. Given that the sequence types as defined here correspond to fungal species, our findings indicate potential fungal networks between trees.

Abstract:

The vast majority of the highly diverse trees in the tropical mountain rain forest of South Ecuador form arbuscular mycorrhizas and previous molecular investigations revealed a high diversity of fungi. Here we present a first trial to link fungal DNA-sequences with defined morphotypes characterized on the basis of partly new mycelial features obtained from field material of one tree species, Alzatea verticillata. Fine roots were halved lengthwise to study the mycelium anatomy on one half and to obtain fungal nuclear rDNA coding for the small subunit rRNA (nucSSU) of Glomeromycota from the other half. Light microscopy revealed conspicuously large amounts of mycelium attaching to the surface of the rootlets. The mycelium formed fine or large branched appressoria-like plates, vesicles of regular or irregular shape, and very fine, multi-branched hyphal systems ensheathed by septate hyphae. These previously undescribed features of the supraradical mycelia combined with intraradical mycelium structures were used for distinguishing of four main morphogroups and subordinate 14 morphotypes. DNA sequences of Glomus-group A, Acaulospora and Gigaspora were obtained and linked to three morphogroups. Two sequence types within Glomus-group A could be tentatively associated to subordinate morphotypes.