Gerald Moser

Altitudinal Changes in Stand Structure and Biomass Allocation of Tropical Mountain Forests in Relation to Microclimate and Soil Chemistry

In tropical montane forests, the decline of tree size with increasing elevation is a well recognized phenomenon (Lieberman et al. 1996; Raich et al. 1997). The decrease aligns with a continuous species shift from lowland forests, to lower, middle and upper montane forests (Gentry et al. 1995). Leaf area index (LAI) also decreases with elevation from lowland to upper montane forest (Kitayama and Aiba 2002). With respect to other structural and functional parameters such as plant biomass and productivity, however, only very limited data exist from tropical montane forests. Altitudinal changes in aboveground biomass and productivity were studied in transects in Malaysia (Kitayama and Aiba 2002), Hawaii (Raich et al. 1997), Puerto Rico (Weaver and Murphy 1990) and Jamaica (Tanner 1980), some of them covering only a few hundred meters of altitudinal distance. The data base is even more limited if belowground biomass is considered: for example, a combined assessment of aboveand belowground biomass in neotropical montane forests has been conducted in not more than 16 different stands so far, and only exceptionally included altitudinal transects. A better understanding of the causes of tree size reduction with elevation in tropical mountains is closely linked to information on altitudinal changes in biomass, carbon allocation and productivity of montane forests. Although numerous hypotheses focusing on climatic or edaphic constraints of tree growth have been formulated in order to explain this phenomenon (e.g. Bruijnzeel and Proctor 1995; Flenley 1995), all of them are eventually linked to carbon gain and allocation of the trees and their control by the environment. Thus, tree biomass and productivity data (see Chapter 17 in this volume) are of paramount importance. In this chapter, we present detailed aboveand belowground biomass data of an altitudinal transect study in the Ecuadorian Andes. Study aim was to analyze altitudinal changes in forest biomass and tree root/shoot ratio , and to relate them to possible underlying climatic and edaphic factors.

Can joint carbon and biodiversity management in tropical agroforestry landscapes be optimized

Managing ecosystems for carbon storage may also benefit biodiversity conservation, but such a potential ‘win-win’ scenario has not yet been assessed for tropical agroforestry landscapes. We measured above- and below-ground carbon stocks as well as the species richness of four groups of plants and eight of animals on 14 representative plots in Sulawesi, Indonesia, ranging from natural rainforest to cacao agroforests that have replaced former natural forest. The conversion of natural forests with carbon stocks of 227–362 Mg C ha−1 to agroforests with 82–211 Mg C ha−1 showed no relationships to overall biodiversity but led to a significant loss of forest-related species richness. We conclude that the conservation of the forest-related biodiversity, and to a lesser degree of carbon stocks, mainly depends on the preservation of natural forest habitats. In the three most carbon-rich agroforestry systems, carbon stocks were about 60% of those of natural forest, suggesting that 1.6 ha of optimally managed agroforest can contribute to the conservation of carbon stocks as much as 1 ha of natural forest. However, agroforestry systems had comparatively low biodiversity, and we found no evidence for a tight link between carbon storage and biodiversity. Yet, potential win-win agroforestry management solutions include combining high shade-tree quality which favours biodiversity with cacao-yield adapted shade levels.

Lichen and moss communities of Botany Bay, Granite Harbour, Ross Sea, Antarctica.

Abstract Botany Bay is one of the richest sites for lichen and bryophyte biodiversity in continental Antarctica. A total of 29 lichen, nine moss and one liverwort species have been identified. The most extensive vegetation occurs on a sheltered raised beach terrace. Vegetation associations are described and compared to other continental Antarctic localities that also possess a rich vegetation cover. Ordination analysis clearly indicates the importance of the type of water supply, its regularity, the substrate type, and particularly in Botany Bay, the influence of nutrients derived from the local bird population in governing plant distribution and associations. A vegetation map has been produced and can be used as a baseline to assess vegetation changes over time.

Carbon dioxide fertilisation and supressed respiration induce enhanced spring biomass production in a mixed species temperate meadow exposed to moderate carbon dioxide enrichment

The rising concentration of carbon dioxide in the atmosphere ([CO2]) has a direct effect on terrestrial vegetation through shifts in the rates of photosynthetic carbon uptake and transpirational water-loss. Free Air CO2 Enrichment (FACE) experiments aim to predict the likely responses of plants to increased [CO2] under normal climatic conditions. The Giessen FACE system operates a lower [CO2] enrichment regime (480μmolmol-1) than standard FACE (550-600μmolmol-1), permitting the analysis of a mixed species temperate meadow under a [CO2] level equivalent to that predicted in 25-30 years. We analysed the physiological and morphological responses of six species to investigate the effect of moderate [CO2] on spring biomass production. Carbon dioxide enrichment stimulated leaf photosynthetic rates and supressed respiration, contributing to enhanced net assimilation and a 23% increase in biomass. The capacity for photosynthetic assimilation was unaffected by [CO2] enrichment, with no downregulation of rates of carboxylation of Rubisco or regeneration of ribulose-1,5-bisphosphate. Foliar N content was also not influenced by increased [CO2]. Enhanced [CO2] reduced stomatal size, but stomatal density and leaf area index remained constant, suggesting that the effect on gas exchange was minimal.

The Carbon Balance of Tropical Mountain Forests Along an Altitudinal Transect

Not much is known about the role of tropical mountain forests in the global carbon cycle. This chapter summarises a decade of research on C pools and C fluxes in Andean mountain forests of the San Francisco region along an elevation transect from 1,000 m to 3,000 m a.s.l. based on measurements in 5 (3) intensively studied stands at five elevations and supplementary data collected in additional 54 forest plots at three elevations covering different topographic positions at these altitudes. With ecosystem C pools in the range of 320–370 Mg C ha−1, these forests store equally large, or even larger, amounts of C than neotropical lowland forests, despite the decrease in aboveground biomass with elevation. Gross and net primary production (NPP) and net ecosystem production all decrease largely with elevation while fine root production seems to increase. Our results show that tropical mountain forests are playing an important, yet underestimated, role as C stores.

Is light interception of understorey species facilitated by light reflection from plant neighbours

Background: Facilitation is an ecological process that has previously been discussed largely in relation to the modification of abiotic conditions in extreme habitats. Here, we introduce the concept of reflected radiation as a potential facilitation mechanism that may raise the beneficiary’s resource level in light-limited habitats. Objectives: We examined whether plants may be able to use their spatial architecture to increase their light absorption through the use of radiation reflected by their neighbours. We tested if this interaction resulted in increased biomass or leaf area between the respective pairs of species. Methods: We determined the biomass and leaf area of eight common herb-layer species, composed of four grass and four herb species, in a beech forest. Plant three-dimensional architecture was digitised and used to simulate reflected and absorbed radiation between the species in a virtual black box. To accomplish this, a so-called light donor plant (which reflected light from its leaf surfaces) was surrounded by four receptor plants (which absorbed this reflected radiation) at a distance of 10 cm. This was repeated using every combination of the available species. We established a ray-trace simulation, including measured light reflection and transmission rates of leaves that enabled us to quantify the relative light absorption by receptor plants, expressed as brightness per leaf area, and estimated the amount of incoming photons. Furthermore, we calculated Seifan’s importance index as an indicator for the relevance of the postulated facilitation effect on plant biomass and leaf area. Results: The leaves of the species studied reflected ca. 7% of radiation between 400 and 700 nm and 18% between 540 to 650 nm of daily incident photon flux density, corresponding to the accessory pigments’ range of efficacy. An average of 0.19% of radiation reflected by a donor plant reached a receptor plant. The benefits to receptor plants varied significantly with donor identity. Conspecific donors supplied significantly larger benefits for Stellaria, Galium, Brachypodium and Hordelymus, which are rhizomatous plants with short stolons. Clones of these species may be able to increase their daily light intake through absorption of reflected light by 0.2%, 0.5–5.0%, 5.0% and 0.6–11.6%, respectively, depending on the number of donor ramets and on the distance between the donor and receptor ramets. Nonetheless, the estimated conspecific facilitation effects through light reflectance within a single clone did not translate into increased biomass. Conclusion: As light intensity decreases with distance according to Lambert’s law, a significant increase of light intake through neighbours can only be predicted for plants with a high density of donor ramets, such as clonal species having many ramets within a short distance. We suggest that in strongly light-limited habitats there may be an advantage to a clonal growth strategy due to the observed facilitation effect of absorption of reflected radiation. To evaluate the magnitude of this effect, future studies should concentrate on ‘payback times’ of leaves with low light intake to gauge the period of time necessary for one leaf to offset the necessary investment in photosynthetic light capture, calculated as cost-benefit calculation between the cost of the leaf’s production and the net carbon gain realised by it.

Aureimonas galii sp. nov. and Aureimonas pseudogalii sp. nov. isolated from the phyllosphere of Galium album

Four yellow-pigmented, Gram-stain-negative, rod-shaped bacteria, strains PP-WC-4G-234T, PP-CE-2G-454T, PP-WC-1G-202 and PP-CC-3G-650, were isolated from the phyllosphere of Galium album. The strains shared 99.7-100 % 16S rRNA gene sequence similarity but could be differentiated by genomic fingerprinting using rep- and random amplification of polymorphic DNA PCRs. Phylogenetic analysis based on the 16S rRNA gene placed the strains within the family Aurantimonadaceae with highest 16S rRNA gene sequence similarity of 97.2-97.3 % to the type strain of Aureimonas phyllosphaerae. Sequence similarities to all other Aurantimonadaceae were below 97 %. The main cellular fatty acids of the strains were C18 : 1ω7c as the predominant fatty acid followed by C16 : 0 and summed feature 3 (C16 : 1ω7c/C16 : 1ω8c). The polyamine patterns of strains PP-WC-4G-234T and PP-CE-2G-454T contained sym-homospermidine as a major compound, and the major respiratory quinone was ubiquinone Q-10. Predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, phosphatidylcholine, sulfoquinovosyldiacylglycerol, three unidentified phospholipids and one unidentified lipid only detectable after total lipid staining. The DNA G+C content was 66.4, 68.9, 67.4 and 70.5 mol% for strains PP-WC-4G-234T, PP-CE-2G-454T, PP-WC-1G-202 and PP-CC-3G-650, respectively. Based on phylogenetic, chemotaxonomic and phenotypic analyses we propose two novel species of the genus Aureimonas, Aureimonas galii sp. nov. with PP-WC-4G-234T (=LMG 28655T=CIP 110892T) as the type strain and Aureimonas pseudogalii sp. nov. with PP-CE-2G-454T (=LMG 29411T=CCM 8665T) as the type strain and two further strains representing the same species, PP-WC-1G-202 and PP-CC-3G-650.

Biomass and productivity of fine and coarse roots in five tropical mountain forests stands along an altitudinal transect in southern Ecuador

Background: Data on below-ground production of tropical montane forests along elevation gradients are scarce. Aims: To determine fine, coarse and large root biomass and productivity along a 2000 m elevation transect. Methods: In five south Ecuadorian mountain forests along a transect from 1000 to 3000 m above sea level, fine (< 2 mm diameter), coarse (2–50 mm) and large root biomass (> 50 mm) were analysed by soil coring and excavation of soil pits. Fine root production was estimated synchronously by three different approaches (sequential soil coring, the ingrowth core method, and the mini-rhizotron technique). Coarse and large root production was estimated by recording diameter increment using dendrometer tapes. Results: Fine root biomass increased four-fold between 1000 and 3000 m; coarse and large root biomass doubled. The three approaches for estimating fine root production yielded highly divergent results, with the mini-rhizotron approach giving the most reliable data, and indicating a significant increase in fine root production with elevation. Conclusions: Our results indicate a marked carbon allocation shift from above- to below-ground towards higher elevations, which is probably a consequence of increasing nutrient limitation of tree growth with increasing elevation.

Proposal of Mucilaginibacter phyllosphaerae sp. nov. isolated from the phyllosphere of Galium album.

A pink-pigmented, Gram-stain-negative, rod-shaped, non-spore-forming bacterial strain, PP-F2F-G21T, was isolated from the phyllosphere of Galium album. Phylogenetic analysis of the nearly full-length 16S rRNA gene sequence of strain PP-F2F-G21T showed the closest relationship to type strains of the species Mucilaginibacter lutimaris (97.7 %), Mucilaginibacter soli (97.3 %) and Mucilaginibacter rigui (97.1 %). Sequence similarities to all other type strains were below 97 %. The predominant cellular fatty acids of strain PP-F2F-G21T are C16 : 1 ω7c/iso-C15 : 0 2-OH (measured as summed feature 3 fatty acids) and iso-C15 : 0 followed by iso-C17 : 0 3-OH, C16 : 1 ω5c and C16 : 0. The major compound in the polyamine pattern was sym-homospermidine and the diamino acid of the peptidoglycan was meso-diaminopimelic acid. The quinone system was exclusively composed of menaquinone MK-7. The polar lipid profile contained the major lipid phosphatidylethanolamine and in addition 18 unidentified lipids. Based on phylogenetic, chemotaxonomic and phenotypic analyses, we propose a novel species of the genus Mucilaginibacter named Mucilaginibacter phyllosphaeraesp. nov. The type strain is PP-F2F-G21T (=CCM 8625T=CIP 110921T=LMG 29118T).

Proposal of Mucilaginibacter galii sp. nov. isolated from leaves of Galium album

A pale-pink-pigmented, Gram-stain-negative, rod-shaped, non-spore-forming bacterial strain, PP-F2F-G47T, was isolated from the phyllosphere of the herbaceous plant Galium album. Phylogenetic analysis based on the nearly full-length 16S rRNA gene sequence revealed highest sequence similarity to the type strains of Mucilaginibacter daejeonensis (96.2 %), Mucilaginibacter dorajii (95.7 %) and Mucilaginibacter phyllosphaerae (95.5 %). 16S rRNA gene sequence similarities to all other type strains were below 95.5 %. The predominant cellular fatty acids of the strain were C16 : 1ω7c/iso-C15 : 0 2-OH (measured as summed feature 3) and iso-C15 : 0. The major compound in the polyamine pattern was sym-homospermidine and major quinone was menaquinone MK-7. The polar lipid profile was composed of phosphatidylethanolamine and several unidentified aminolipipids, phospholipids, aminophospholipids and lipids without a functional group. A sphingophospholipid could not be detected but a ninhydrin-positive alkaline-stable lipid was visible. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid. Based on phylogenetic, chemotaxonomic and phenotypic analyses a novel species is proposed, Mucilaginibacter galii sp. nov., with PP-F2F-G47T (=CCM 8711T=CIP 111182T=LMG 29767T) as the type strain.