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Christoph Leuschner - One of the best experts on this subject based on the ideXlab platform.
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Effects of Nutrient Addition on the Productivity of Montane Forests and Implications for the Carbon Cycle
Ecosystem Services Biodiversity and Environmental Change in a Tropical Mountain Ecosystem of South Ecuador, 2013Co-Authors: Jürgen Homeier, Dietrich Hertel, Christoph Leuschner, Guntars O. Martinson, Achim Bräuning, Nixon Cumbicus, Susanne Spannl, Edzo VeldkampAbstract:Both carbon storage and sequestration are major ecosystem services provided by Forests. The NUMEX (Ecuadorian NUtrient Manipulation EXperiment) study aims to identify the underlying mechanisms for the variation of these services as affected by future changes in nutrient availability. The ongoing experiment is being conducted in southern Ecuador to improve our understanding of the effects of continuous moderate N and P addition to tropical Montane forest ecosystems. This chapter summarizes the short-term effects of nutrient addition evident at the end of the experiment’s first year. The rapid responses of the studied Andean Montane Forests to N and P addition observed at this early stage of the experiment illustrate the vulnerability of the Forests to higher nutrient deposition.
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altitudinal changes in stand structure and biomass allocation of tropical mountain Forests in relation to microclimate and soil chemistry
2008Co-Authors: Gerald Moser, Marina Röderstein, Dietrich Hertel, Nathalie Soethe, Christoph LeuschnerAbstract: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.
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Altitudinal Change in LAI and Stand Leaf Biomass in Tropical Montane Forests: a Transect Study in Ecuador and a Pan-Tropical Meta-Analysis
Ecosystems, 2007Co-Authors: Gerald Moser, Dietrich Hertel, Christoph LeuschnerAbstract:Leaf area index (LAI) is a key parameter controlling plant productivity and biogeochemical fluxes between vegetation and the atmosphere. Tropical Forests are thought to have comparably high LAIs; however, precise data are scarce and environmental controls of leaf area in tropical Forests are not understood. We studied LAI and stand leaf biomass by optical and leaf mass-related approaches in five tropical Montane Forests along an elevational transect (1,050–3,060 m a.s.l.) in South Ecuador, and conducted a meta-analysis of LAI and leaf biomass data from tropical Montane Forests around the globe. Study aims were (1) to assess the applicability of indirect and direct approaches of LAI determination in tropical Montane Forests, (2) to analyze elevation effects on leaf area, leaf mass, SLA, and leaf lifespan, and (3) to assess the possible consequences of leaf area change with elevation for Montane forest productivity. Indirect optical methods of LAI determination appeared to be less reliable in the complex canopies than direct leaf mass-related approaches based on litter trapping and a thorough analysis of leaf lifespan. LAI decreased by 40–60% between 1,000 and 3,000 m in the Ecuador transect and also in the pan-tropical data set. This decrease indicates that canopy carbon gain, that is, carbon source strength, decreases with elevation in tropical Montane Forests. Average SLA decreased from 88 to 61 cm^2 g^−1 whereas leaf lifespan increased from 16 to 25 mo between 1,050 and 3,060 m in the Ecuador transect. In contrast, stand leaf biomass was much less influenced by elevation. We conclude that elevation has a large influence not only on the leaf traits of trees but also on the LAI of tropical Montane Forests with soil N (nitrogen) supply presumably being the main controlling factor.
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Above- and below-ground litter production in three tropical Montane Forests in southern Ecuador
Journal of Tropical Ecology, 2005Co-Authors: Marina Röderstein, Dietrich Hertel, Christoph LeuschnerAbstract: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.
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size and structure of fine root systems in old growth and secondary tropical Montane Forests costa rica
Biotropica, 2003Co-Authors: Dietrich Hertel, Christoph Leuschner, Dirk HolscherAbstract:Abstract The fine root systems of three tropical Montane Forests differing in age and history were investigated in the Cordillera Talamanca, Costa Rica. We analyzed abundance, vertical distribution, and morphology of fine roots in an early successional forest (10–15 years old, ESF), a mid-successional forest (40 years old, MSF), and a nearby undisturbed old-growth forest (OGF), and related the root data to soil morphological and chemical parameters. The OGF stand contained a 19 cm deep organic layer on the forest floor (i.e., 530 mol C/m2), which was two and five times thicker than that of the MSF (10 cm) and ESF stands (4 cm), respectively. There was a corresponding decrease in fine root biomass in this horizon from 1128 g dry matter/m2 in the old-growth forest to 337 (MSF) and 31 g/m2 (ESF) in the secondary Forests, although the stands had similar leaf areas. The organic layer was a preferred substrate for fine root growth in the old-growth forest as indicated by more than four times higher fine root de...
Renton Righelato - One of the best experts on this subject based on the ideXlab platform.
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Carbon storage and sequestration of re-growing Montane Forests in southern Ecuador
Forest Ecology and Management, 2016Co-Authors: Dominick V. Spracklen, Renton RighelatoAbstract:Abstract 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 (>40 years old) forest was found to be 158 ± 38 Mg ha −1 of land surface at 1000 m elevation and 104 ± 25 Mg ha −1 of land surface at 2250 m 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 (1–2 years) stored 2–18 Mg ha −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 10 Mg ha −1 yr −1 at 1000 m elevation and 4 Mg ha −1 yr −1 at 2250 m elevation, for the first 5–7 years after pasture abandonment. After 12–15 years, accumulation of AGB slowed to 1–2 Mg ha −1 yr −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
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Tropical Montane Forests are a larger than expected global carbon store
Biogeosciences, 2014Co-Authors: Dominick V. Spracklen, Renton RighelatoAbstract:Abstract. Tropical Montane Forests (TMFs) are recognized for the provision of hydrological services and the protection of biodiversity, but their role in carbon storage is not well understood. We synthesized published observations (n = 94) of above-ground biomass (AGB) from forest inventory plots in TMFs (defined here as Forests between 23.5° N and 23.5° S with elevations ≥ 1000 m a.s.l.). We found that mean (median) AGB in TMFs is 271 (254) t per hectare of land surface. We demonstrate that AGB declines moderately with both elevation and slope angle but that TMFs store substantial amounts of biomass, both at high elevations (up to 3500 m) and on steep slopes (slope angles of up to 40°). We combined remotely sensed data sets of forest cover with high resolution data of elevation to show that 75% of the global planimetric (horizontal) area of TMF are on steep slopes (slope angles greater than 27°). We used our remote sensed data sets to demonstrate that this prevalence of steep slopes results in the global land surface area of TMF (1.22 million km2) being 40% greater than the planimetric area that is the usual basis for reporting global land surface areas and remotely sensed data. Our study suggests that TMFs are likely to be a greater store of carbon than previously thought, highlighting the need for conservation of the remaining Montane Forests.
Scott L. Stephens - One of the best experts on this subject based on the ideXlab platform.
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Fire history differences in adjacent Jeffrey pine and upper Montane Forests in the eastern Sierra Nevada
International Journal of Wildland Fire, 2001Co-Authors: Scott L. StephensAbstract:Fire history and forest structural characteristics of adjacent Jeffrey pine (Pinus jeffreyi) and upper Montane Forests was investigated in the eastern Sierra Nevada at the University of California Valentine Natural Reserve. Jeffrey pine Forests had lower canopy cover, higher amounts of fine fuels, and higher shrub cover when compared to upper Montane forest that were dominated by red fir (Abies magnifica). Fire dates were determined using standard dendrochronolgy techniques from fire-scarred Jeffrey pine, lodgepole pine (Pinus contorta var. murrayana), red f ir, and western white pine (Pinus monticola) trees, snags, stumps, and downed logs. Fires were recorded from 1745 to 1889 and mean fire return intervals were 9 and 24.7 years for the Jeffrey pine and upper Montane forest types, respectively. The median fire return interval was 9.0 years for Jeffrey pine and 24.0 years for upper Montane Forests. Significant differences were found in mean fire intervals and fire history distributions between the two similarly sized fire history plots even though they were only separated by approximately 100 m. This study suggests that fire regimes can vary over very fine spatial scales. Differences in fire regimes are likely due to differences in fuel beds and fire behavior.
Suzanne M. Prober - One of the best experts on this subject based on the ideXlab platform.
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Adaptation services and pathways for the management of temperate Montane Forests under transformational climate change
Climatic Change, 2016Co-Authors: Matthew J Colloff, Michael D. Doherty, Michael Dunlop, Robert M Wise, Sandra Lavorel, Suzanne M. ProberAbstract:In regions prone to wildfire, a major driver of ecosystem change is increased frequency and intensity of fire events caused by a warming, drying climate. Uncertainty over the nature and extent of change creates challenges for how to manage ecosystems subject to altered structure and function under climate change. Using Montane Forests in south-eastern Australia as a case study, we addressed this issue by developing an ecosystem state-andtransition model based on a synthesis of expert knowledge and published data, with fire frequency and intensity as drivers. We then used four steps to determine future adaptation options: (1) estimation of changes in ecosystem services under each ecosystem state to identify adaptation services: the ecosystem processes and services that help people adapt to environmental change; (2) identification and sequencing of decision points to maintain each ecosystem state or allow transition to an alternative state; (3) analysis of interactions between societal values, scientific and management knowledge and institutional rules (vrk) required to reframe the decision context for future management, and (4) determining options for an adaptation pathway for management of Montane Forests under climate change. Our approach is transferable to other ecosystems for which alternative states can be predicted under climate change.
Jörg Müller - One of the best experts on this subject based on the ideXlab platform.
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Environmental key factors and their thresholds for the avifauna of temperate Montane Forests
Forest Ecology and Management, 2008Co-Authors: Christoph Moning, Jörg MüllerAbstract:Abstract Mixed Montane Forests cover large tracts of the low mountain ranges that dominate Central Europe and also contain much of the area that is important to forest related nature conservation. However, beyond general patterns little is known about ecologically effective driving factors in this habitat. This results in a lack of precise values that can be used to formulate guidelines for nature conservation oriented management strategies. To improve this situation, we used birds as indicators for forest habitat qualities. The avifauna of the Bavarian Forest National Park was investigated on 293 plots of 1 ha along four transects ranging from 655 to 1420 m a.s.l. The investigated forest includes a wide structural gradient ranging from very open, grass dominated areas of the high Montane zone, where mature spruce trees have died after bark beetle infestation, to mature mixed Montane Forests at lower elevations. Altitude is the main factor driving composition of bird assemblages in the Montane Forests. We analysed occurrence of species using a subdivided dataset, in which the altitude could be eliminated as an important influencing factor, by implementation of General Linear Models under consideration of spatial effects and utilising maximally selected rank statistics. Our analysis identified canopy cover as the most influential factor in Montane and high Montane Forests. Forest age is the second most important gradient in Montane Forests. The tree species composition has an influence on a limited number of species. In high Montane Forests, bark beetle infestations have led to a complete change in the avifauna composition. The distinct, species-poor group that is found here includes some species that are generally decreasing in abundance in Central Europe. By calculating threshold values for the environmental variables which were identified as important, we were able to formulate the following concrete management recommendations: (1) To create conditions suitable for the whole range of species associated with openings in the canopy, the full spectrum of canopy-openness ranging from 5% to 70% should be realized on the stand scale throughout a whole forest landscape. (2) To sustain the whole range of cavity-breeding species and species of mature Forests, the age of Central European mixed Montane Forests needs to surpass 200–220 years. (3) To support the deciduous forest species in mixed Montane stands a minimum of 60% cover of deciduous trees at least in single stands that are maximally few kilometres apart is required. Among the threshold values, we identified cascade-like threshold sequences that represent the ecological niches of the individual species with respect to the environmental variables, which contrasts with species groups where the collective threshold value is a universal threshold that applies to the whole group.
