Dorothee Sandmann

Tropical Andean Forests Are Highly Susceptible to Nutrient Inputs—Rapid Effects of Experimental N and P Addition to an Ecuadorian Montane Forest

Tropical regions are facing increasing atmospheric inputs of nutrients, which will have unknown consequences for the structure and functioning of these systems. Here, we show that Neotropical montane rainforests respond rapidly to moderate additions of N (50 kg ha−1 yr−1) and P (10 kg ha−1 yr−1). Monitoring of nutrient fluxes demonstrated that the majority of added nutrients remained in the system, in either soil or vegetation. N and P additions led to not only an increase in foliar N and P concentrations, but also altered soil microbial biomass, standing fine root biomass, stem growth, and litterfall. The different effects suggest that trees are primarily limited by P, whereas some processes—notably aboveground productivity—are limited by both N and P. Highly variable and partly contrasting responses of different tree species suggest marked changes in species composition and diversity of these forests by nutrient inputs in the long term. The unexpectedly fast response of the ecosystem to moderate nutrient additions suggests high vulnerability of tropical montane forests to the expected increase in nutrient inputs.

Moderate changes in nutrient input alter tropical microbial and protist communities and belowground linkages.

We investigated the response of soil microbial communities in tropical ecosystems to increased nutrient deposition, such as predicted by anthropogenic change scenarios. Moderate amounts of nitrogen and phosphorus and their combination were added along an altitudinal transect. We expected microorganisms and microbial grazers (testate amoebae) to significantly respond to nutrient additions with the effect increasing with increasing altitude and with duration of nutrient additions. Further, we expected nutrients to alter grazer–prey interrelationships. Indeed, nutrient additions strongly altered microbial biomass (MB) and community structure as well as the community structure of testate amoebae. The response of microorganisms varied with both altitude and duration of nutrient addition. The results indicate that microorganisms are generally limited by N, but saprotrophic fungi also by P. Also, arbuscular mycorrhizal fungi benefited from N and/or P addition. Parallel to MB, testate amoebae benefited from the addition of N but were detrimentally affected by P, with the addition of P negating the positive effect of N. Our data suggests that testate amoeba communities are predominantly structured by abiotic factors and by antagonistic interactions with other microorganisms, in particular mycorrhizal fungi, rather than by the availability of prey. Overall, the results suggest that the decomposer system of tropical montane rainforests significantly responds to even moderate changes in nutrient inputs with the potential to cause major ramifications of the whole ecosystem including litter decomposition and plant growth.

New and little known species of oribatid mites of the family Haplozetidae (Acari, Oribatida) from Ecuador

Abstract We described two new species, Haplozetes paraminimicoma sp. n. and Protoribates ecuadoriensis sp. n. from Ecuador. Additionally, a detailed supplementary description of Trachyoribates (Rostrozetes) glaber (Beck, 1965) is given on the basis of Ecuadorian specimens, which was known previously only from Peru. An annotated checklist of all identified taxa of Haplozetidae from Ecuador is presented.

Contributions to the knowledge of oribatid mites of Indonesia. 2. The genus Pergalumna (Galumnidae) with description of a new species and key to known species in the Oriental region (Acari, Oribatida).

Abstract A new species of oribatid mite of the genus Pergalumna (Oribatida, Galumnidae) is described from litter and soil materials in Sumatra, Indonesia. Pergalumna paraindistincta sp. n. is morphologically most similar to Pergalumna indistincta Ermilov & Anichkin, 2011, Pergalumna pertrichosa Mahunka, 1995 and Pergalumna sura Balogh, 1997; however, the new species differs from Pergalumna indistincta by the smaller body size, presence of long adanal setae ad1, and large, single median pore in females and males; from Pergalumna pertrichosa by the smaller body size, presence of three pairs of notogastral porose areas, elongated A1 and minute anal setae; from Pergalumna sura by the presence of strong adanal setae ad1, large, single median pore in females and males, and shorter bothridial setae. Furthermore, Pergalumna hawaiiensis hawaiiensis (Jacot, 1934) and Pergalumna panayensis Ermilov & Corpuz-Raros, 2015 are recorded for the first time in the Indonesian fauna. An identification key to the known species of Pergalumna in the Oriental region is given.

Oribatid mites of the superfamily Oppioidea from Ecuador (Acari: Oribatida)

Abstract An annotated checklist of identified Ecuadorian Oppioidea (10 species of 10 genera of three families) is presented. The genera Hammerella, Taiwanoppia, subgenera Hammerella (Woasella), Taiwanoppia(Paragloboppia) and the species T. (P.) trichotos (Balogh et Mahunka, 1977) are recorded for the first time in Ecuador. One new species of the family Granuloppiidae — Hammerella (Woasella) parasufflata sp. nov. — is described from the upper organic soil layer in a mostly undisturbed rain forest. This species differs from the type species of the subgenus, H. (W.) sufflata Franklin et Woas, 1992 from Brazil by the absence of translamella, presence of two prodorsal tubercles, localization of notogastral (la, lm) and aggenital setae, localization of sensillar branches, morphology of some subcapitular setae and the location of lyrifissures iad.

Two new species of oribatid mites of the genus Truncozetes (Acari, Oribatida, Epactozetidae) from Ecuador

Abstract Two new oribatid mite species of the genus Truncozetes (Oribatida, Epactozetidae), Truncozetes ecuadoriensis sp. n. and Truncozetes monodactylus sp. n., are described from the Ecuadorian soils. The morphology of the gnathosoma and the legs is presented in detail for the first time for the species of Truncozetes. An identification key to all known species of the family Epactozetidae is given.

Two new species of Schalleria (Acari: Oribatida: Microzetidae) from Ecuador with a key to all species of the genus

Two new microzetid mite species of the genus Schalleria, Schalleria brevisetosa sp. nov. and Schalleria pectinata sp. nov., are described. The morphology of the gnathosoma and the legs is presented in detail for the first time for a species of this genus. An identification key to all known species of Schalleria is provided. http://zoobank.org/urn:lsid:zoobank.org:pub:32E03098-C8EA-46C6-B46F-326148374207

New species of oribatid mites of the genera Hermannobates and Rhynchoribates (Acari: Oribatida: Hermanniellidae, Rhynchoribatidae) from Ecuador

Abstract Two new species of oribatid mites, Hermannobates dilatatus sp. nov. and Rhynchoribates longisetosus sp. nov., are described from Ecuadorian soils. Hermannobates dilatatus sp. nov. is most similar to H. ruseki Starý, 1998, however, it differs from the latter by the smaller body size, absence of flagelliform posterior notogastral setae, bacilliform exuvial setae d1E and e1E, longer adanal setae ad1 and bifurcate epimeral setae1a, 1c, 2a and 4b.Rhynchoribates longisetosus sp. nov. is most similar to R. insignis Balogh & Mahunka, 1969, however, it differs from the latter by the rostral setae bent backwards and long, flagelliform notogastral setae.

New oribatid mites of the genera Machadobelba and Campachipteria (Acari: Oribatida) from Ecuador

Abstract Two new oribatid mite species, Machadobelba longiciliata sp. nov. (Machadobelbidae) and Campachipteria brevisetosa sp. nov. (Achipteriidae), are described from upper organic soil layer in mostly undisturbed rain forest of Podocarpus National Park, Ecuador. Machadobelba longiciliata sp. nov. is most similar to Machadobelba descombesi Mahunka, however it differs from the latter by the structures of sensilli and median notogastral tubercles, length of notogastral setae and presence of porose areas in anogenital region. Campachipteria brevisetosa sp. nov. is most similar to Campachipteria sibirica (Krivolutsky et Grishina), however it differs from the latter by the structures of sensilli and lamellar setae, and length of process of pteromorphs. The genus Campachipteria is recorded for the first time in Ecuador.

Nutrient Additions Affecting Matter Turnover in Forest and Pasture Ecosystems

Nutrient inputs into ecosystems of the tropical mountain rainforest region are projected to further increase in the next decades. To investigate whether important ecosystem services such as nutrient cycling and matter turnover in native forests and pasture ecosystems show different patterns of response, two nutrient addition experiments have been established: NUMEX in the forest and FERPAST at the pasture. Both ecosystems already responded 1.5 years after the start of nutrient application (N, P, NP, Ca). Interestingly, most nutrients remained in the respective systems. While the pasture grass was co-limited by N and P, most tree species responded to P addition. Soil microbial biomass in the forest litter layer increased after NP fertilization pointing to nutrient co-limitation. In pasture soils, microorganisms were neither limited by N nor P. The results support the hypothesis that multiple and temporally variable nutrient limitations can coexist in tropical ecosystems.