Publikationen
Es wurden 14 Publikationen gefunden
Guillen Otero, T.; Kessler, M. & Homeier, J. (2024): Fern mycorrhizae do not respond to fertilization in a tropical montane forest. Plant-Environment Interactions 5(2), e10139.
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DOI: 10.1002/pei3.10139
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Abstract:
Abstract:
Ferns are known to have a lower incidence of mycorrhization than angiosperms. It
has been suggested that this results from carbon being more limiting to fern growth
than nutrient availability, but this assertion has not been tested yet. In the present
study, we took advantage of a fertilization experiment with nitrogen and phosphorus
on cloud forest plots of the Ecuadorean Andes for 15 years. A previous analysis
revealed changes in the abundances of fern species in the fertilized plots compared
to the control plots and hypothesized that this might be related to the responses of
the mycorrhizal relationships to nutrient availability. We revisited the plots to assess
the root-associated
fungal communities of two epiphytic and two terrestrial fern
species that showed shifts in abundance. We sampled and analyzed the roots of 125
individuals following a metabarcoding approach. We recovered 1382 fungal ASVs, with
a dominance of members of Tremellales (Basidiomycota) and Heliotales (Ascomycota).
The fungal diversity was highly partitioned with little overlap between individuals. We
found marked differences between terrestrial and epiphytic species, with the latter
fundamentally missing arbuscular mycorrhizal fungi (AMF). We found no effect of
fertilization on the diversity or relative abundance of the fungal assemblages. Still, we
observed a direct impact of phosphorus fertilization on its concentration in the fern
leaves. We conclude that fern–fungi relationships in the study site are not restricted
by nutrient availability and suggest the existence of little specificity on the fungal
partners relative to the host fern species.
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Keywords: |
Ecuador |
nitrogen |
phosphorus |
fertilization |
Arbuscular mycorrhizal fungi |
Wilcke, W.; Velescu, A.; Leimer, S. & Valarezo, C. (2020): Water and Nutrient Budgets of Organic Layers and Mineral Topsoils Under Tropical Montane Forest in Ecuador in Response to 15 Years of Environmental Change. In: Levia, D., Carlyle-Moses, D., Iida, S., Michalzik, B., Nanko, K., Tischer, A. (eds.): Forest-Water Interactions (Ecological Studies 240), Springer, Cham, 565-586.
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DOI: 10.1007/978-3-030-26086-6_23
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Abstract:
Abstract:
We quantified the changes in macronutrient storages of the soil in a remote Andean tropical montane rain forest on the rim of the Amazon basin from 1998 to 2013. In the studied 15 years, the N, P, and S fluxes in throughfall+stemflow increased significantly, while those of Ca decreased and of Mg and K remained unchanged. The main reasons for increasing nutrient inputs were Amazonian forest fires. Ca inputs decreased because of a particularly strong Sahara dust deposition event in 1999/2000. On average of the 15 budgeted years, P and K accumulated in the organic layer at a rate doubling their current storages in 197 and 27 years, respectively. The other macronutrients were on average leached from the organic layer, depleting it in 38 (Mg) to 281 years (N). Nutrient leaching was likely favored by enhanced mineralization driven by climate warming. In the upper 30 cm of the mineral soil, all macronutrients accumulated at rates doubling their storages in 57 (Ca) to 601 years (P). Our results demonstrate that the current environmental change increased the nutrient supply of the studied ecosystem. Increased nutrient supply might shift the ecosystem to a new state and change the chemistry of headwater streams.
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Keywords: |
nitrogen |
phosphorus |
environmental change |
macronutrients |
nutrient storage |
base metals |
sulfur |
Homeier, J.; Báez, S.; Hertel, D. & Leuschner, C. (2017): Editorial: Tropical forest ecosystem responses to increasing nutrient availability. Frontiers in Earth Science 5, 27.
Dietrich, K.; Spöri, E. & Oelmann, Y. (2016): Nutrient addition modifies phosphatase activities along an altitudinal gradient in a tropical montane forest in Southern Ecuador. Frontiers in Earth Science 4, 1-9.
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DOI: 10.3389/feart.2016.00012
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Abstract:
Abstract:
Atmospheric nutrient deposition and climate change are expected to endanger the diversity of tropical forest ecosystems. Nitrogen (N) deposition might influence nutrient fluxes beyond the N cycle by a concomitant increased demand for other nutritional elements such as phosphorus (P). Organisms might respond to the increased P demand by enhanced activity of enzymes involved in releasing inorganic P from organic matter (OM). Our aims were to assess the effect of i) climate shifts (approximated by an altitudinal gradient), and ii) nutrient addition (N, P, N+P) on phosphatase activity (PA) in organic layer and mineral soil of a tropical montane rainforest in Southern Ecuador. A nutrient manipulation experiment (NUMEX) was set up along an altitudinal gradient (1000, 2000, and 3000 m a.s.l.). We determined PA and inorganic and total P concentrations. PA at 1000 m was significantly lower (mean ± standard error: 48 ± 20 µmol p-NP g-1 dm h-1) as compared to 2000 m and 3000 m (119 ± 11 and 137 ± 19, respectively). One explanation might be that very rapid decomposition of OM at 1000 m results in very thin organic layers reducing the stabilization of enzymes and thus, resulting in leaching loss of enzymes under the humid tropical climate. We found no effect of N addition on PA neither in the organic layer nor in mineral soil, probably because of the low nutrient addition rates that showed ambiguous results so far on productivity measures as a proxy for P demand. In the organic layers of P and N+P treatments, we found decreased PA and increased concentrations of inorganic P. This indicates that the surplus of inorganic P reduced the biosynthesis of phosphatase enzymes. PA in megadiverse montane rainforests is likely to be unaffected by increased atmospheric N deposition but reduced upon atmospheric P deposition.
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Keywords: |
Ecuador |
NUMEX |
phosphorus |
fertilization |
tropical montane forest |
phosphatase activity |
Ahlers, J. (2016): Variabilität der Feinstreuquantität und -qualität sowie die Auswirkungen einer kontinuierlichen N und P Düngung entlang eines Höhengradienten im tropischen Bergregenwald Südecuadors University of Goettingen, bachelor thesis
Liedtke, R. (2016): Mobile and Soil Bonded Phosphomonoesterase Activity of the Organic Layer along an Altitudinal Gradient in South Ecuador University of Tuebingen, bachelor thesis
Baldos, A.; Corre, M. & Veldkamp, E. (2015): Response of N cycling to nutrient inputs in forest soils across a 1000–3000 m elevation gradient in the Ecuadorian Andes. Ecology 96(3), 749 - 761.
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DOI: 10.1890/14-0295.1.sm
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Abstract:
Abstract:
Large areas in the tropics receive elevated atmospheric nutrient inputs. Presently, little is known on how nitrogen (N) cycling in tropical montane forest soils will respond to such increased nutrient inputs. We assessed how gross rates of mineral N production (N mineralization and nitrification) and microbial N retention (NH4+ and NO3- immobilization and dissimilatory NO3- reduction to NH4+ [DNRA]) change with elevated N and phosphorus (P) inputs in montane forest soils at 1000-, 2000-, and 3000-m elevations in
south Ecuador. At each elevation, four replicate plots (20320 m each) of control, N (added at 50 kg N ha-1yr-1), P (added at 10 kg P ha-1 yr-1), and combined N x P additions have been established since 2008. We measured gross N cycling rates in 2010 and 2011, using 15N pool dilution techniques with in situ incubation of intact soil cores taken from the top 5 cm of soil. In control plots, gross soil-N cycling rates decreased with increase in elevation, and microbial N retention was tightly coupled with mineral N production. At 1000 m and 2000 m, four-year N and combined N þ P additions increased gross mineral N production but decreased NH4+ and NO3- immobilization and DNRA compared to the control. At 3000 m, four-year N and combined N x P additions increased gross N mineralization rates and decreased DNRA
compared to the control; although NH4+ and NO3- immobilization in the N and NxP plots were not different from the control, these were lower than their respective mineral N production. At all elevations, decreased microbial N retention was accompanied by decreased microbial biomass C and C:N ratio. P addition did not affect any of the soil-N cycling processes. Our results signified that four years of N addition, at a rate expected to occur at these sites, uncoupled the soil-N cycling processes, as indicated by decreased microbial N retention. This fast response of soil-N cycling processes across elevations implies that greater
attention should be paid to the biological implications on montane forests of such uncoupled soil-N cycling.
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Keywords: |
NUMEX |
nitrogen |
phosphorus |
Matson, A.; Corre, M. & Veldkamp, E. (2014): Nitrogen cycling in canopy soils of tropical montane forests responds rapidly to indirect N and P fertilization. Global Change Biiology 20, 3802-3813.
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DOI: 10.1111/gcb.12668
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Abstract:
Abstract:
Although the canopy can play an important role in forest nutrient cycles, canopy-based processes are often overlooked in studies on nutrient deposition. In areas of nitrogen (N) and phosphorus (P) deposition, canopy soils may retain a significant proportion of atmospheric inputs, and also receive indirect enrichment through root uptake followed by throughfall or recycling of plant litter in the canopy. We measured net and gross rates of N cycling in canopy soils of tropical montane forests along an elevation gradient and assessed indirect effects of elevated nutrient inputs to the forest floor. Net N cycling rates were measured using the buried bag method. Gross N cycling rates were measured using 15N pool dilution techniques. Measurements took place in the field, in the wet and dry season,using intact cores of canopy soil from three elevations (1000, 2000 and 3000 m). The forest floor had been fertilized biannually with moderate amounts of N and P for 4 years; treatments included control, N, P, and N + P. In control plots, gross rates of NH4+ transformations decreased with increasing elevation; gross rates of NO3- transformations
did not exhibit a clear elevation trend, but were significantly affected by season. Nutrient-addition effects were different at each elevation, but combined N + P generally increased N cycling rates at all elevations. Results showed that canopy soils could be a significant N source for epiphytes as well as contributing up to 23% of total (canopy + forest floor) mineral N production in our forests. In contrast to theories that canopy soils are decoupled from nutrient cycling in forest floor soil, N cycling in our canopy soils was sensitive to slight changes in forest floor nutrient availability.Long-term atmospheric N and P deposition may lead to increased N cycling, but also increased mineral N losses from the canopy soil system.
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Keywords: |
NUMEX |
nitrogen |
canopy |
phosphorus |
Rehmus, A.; Bigalke, M.; Valarezo, C.; Mora Castillo, J.R. & Wilcke, W. (2015): Aluminium toxicity to tropical montane forest tree seedlings in southern Ecuador: Response of the nutrient status to elevated Al concentrations. Plant and Soil 388, 87-97.
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DOI: 10.1007/s11104-014-2276-5
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Abstract:
Abstract:
Aims We determined the reasons why in nutrient solution increasing Al concentrations>300 ?M inhibited
shoot biomass production of Cedrela odorata L., Heliocarpus americanus L., and Tabebuia chrysantha
(Jacq.) G. Nicholson while 300 ?M Al stimulated root biomass production of Tabebuia chrysantha.
Methods Nutrient concentrations in plant tissue after a hydroponic growth experiment were determined.
Results Increasing Al concentrations significantly decreased Mg concentrations in leaves. Phosphorus
concentrations in roots of C. odorata and T. chrysantha were significantly highest in the treatment with 300 ?M Al and correlated significantly with root biomass.
Conclusions Shoot biomass production was likely inhibited by reduced Mg uptake, impairing photosynthesis.
The stimulation of root growth at low Al concentrations can be possibly attributed to improved P uptake.
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Keywords: |
phosphorus |
aluminum toxicity |
tropical forest tree seedling |
nutrient deficiency |
growth stimulation |
Kotowska, M. & Werner, F.A. (2013): Environmental controls over methane emissions from bromeliad phytotelmata: The role of phosphorus and nitrogen availability, temperature, and water content. GLOBAL BIOGEOCHEMICAL CYCLES 27, 1-8.
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DOI: 10.1002/2013GB004612
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Abstract:
Abstract:
Tank bromeliads are common epiphytic plants throughout neotropical forests that store
signi?cant amounts of water in phytotelmata (tanks) formed by highly modi?ed leafs.
Methanogenic archaea in these tanks have recently been identi?ed as a signi?cant source of
atmospheric methane. We address the effects of environmental drivers (temperature, tank
water content, sodium phosphate [P], and urea [N] addition) on methane production in
anaerobically incubated bromeliad slurry and emissions from intact bromeliad tanks in
montane Ecuador. N addition ? 1 mg g 1 had a signi?cantly positive effect on headspace
methane concentrations in incubation jars while P addition did not affect methane
production at any dosage (? 1 mg g 1 ). Tank bromeliads (Tillandsia complanata) cultivated
in situ showed signi?cantly increased ef?uxes of methane in response to the addition of
26 mg N addition per tank but not to lower dosage of N or any dosage of P (? 5.2 mg plant 1 ).
There was no signi?cant interaction between N and P addition. The brevity of the
stimulatory effect of N addition on plant methane ef?uxes (1–2 days) points at N
competition by other microorganisms or bromeliads. Methane ef?ux from plants closely
followed within-day temperature ?uctuations over 24 h cycles, yet the dependency of
temperature was not exponential as typical for terrestrial wetlands but instead linear. In
simulated drought, methane emission from bromeliad tanks was maintained with minimum
amounts of water and regained after a short lag phase of approximately 24 h. Our results
suggest that methanogens in bromeliads are primarily limited by N and that direct effects of
global change (increasing temperature and seasonality, remote fertilization) on bromeliad
methane emissions are of moderate scale.
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Keywords: |
nutrients |
gas emission |
NUMEX |
N-cycle |
nitrogen |
Gas exchange |
phosphorus |
nutrient manipulation |
nutrient limitation |
phosphorus availability |
nutrient cycle |
methane |
Graefe, S.; Hertel, D. & Leuschner, C. (2010): N, P and K limitation of fine root growth along an elevation transect in tropical mountain forests. Acta Oecologica 36, 537-542.
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DOI: 10.1016/j.actao.2010.07.007
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Abstract:
Abstract:
It is generally assumed that tree growth in tropical low-elevation forests is primarily limited by phosphorus
while nitrogen limitation is more prominent in tropical montane forests where temperature is
lower and the soils are poorly developed. We tested this hypothesis in mountain rainforests of South
Ecuador by investigating the growth response of tree fine roots to N, P and K fertilization in ingrowth cores
exposed at 1050 m (pre-montane) and 3060 m (upper montane) elevation. Root growth into unfertilized
ingrowth cores (control treatment) was about 10 times slower at 3060 m than at 1050 m. At 1050 m, root
growth was stimulated not only by P, but also by N and K. In contrast, N was the only element to promote
root growth at 3060 m. The N concentration in fine root biomass dropped to nearly a third between 1050
and 3060 m, those of P, K, Ca and Mg decreased as well, but to a lesser degree. According to a 15NO3
15NH4
tracer study along the slope, tree fine roots accumulated nitrate and ammonium in root biomass at similar
rates between 1050 and 3060 m, despite lower temperatures higher upslope.We conclude that the nature
of nutrient limitation of tree fine root growth changes with elevation from an apparent co-limitation by
P together with N and K at 1050 m to predominant N limitation at 3060 m, which is also reflected by low
foliar N concentrations. Increasing N limitation may have caused the high fine root biomass and root/shoot
ratio in the high elevation forest, while the capability of the roots to acquire mineral N apparently was not
affected by lower temperatures at high elevations.
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Keywords: |
nitrogen |
phosphorus |
potassium |
nutrient limitation |
ecuador |
fine roots |
15N tracer study |
Pena Herrera, J.M. (2013): Response of N, P, organic C and Cl concentrations in soil solution to varying precipitation in a tropical montane rain forest of Ecuador University of Berne, Geographic Institute, master thesis
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The current climate change in the tropical Andean rain forests in south Ecuador alters the distribution of rain events with increasing dry and wet phases. The present research focuses on the concentration response of some elements to signicant changes on rainfall distribution. It seeks to determine whether changes in the concentrations of elements in an ecosystem of a rainforest are an eect of dilution by precipitation or other factors that may be aecting these variations, such as microbiological activities. The study examines chloride, ammonium, nitrate, phosphate, total organic carbon (TOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) in soil solution as well as the ratio of organic nitrogen to organic carbon (C : N) in soil solution samples taken in a tropical rain forest of Ecuador. Soil samples were taken weekly from 1998 to 2007, both below the organic layer and 15 and 30 cm into the mineral layer. Concentrations were measured with a chloride electrode , Continuous Flow Analyzer (CFA for ammonium, nitrate, DON, and DOP) and Total Organic Carbon Analyzer. The results were analyzed with statistical
software packages R and SPSS using statistical methods of descriptive statistics and ANOVA. The average weekly precipitation was 38.73 mm and weekly precipitation varied between 0 and 155.2 mm. The variation of chloride concentrations served as reference to detect dilution/concentration effects of the other elements because it is assumed that chloride concentrations behave inversely proportional to the volume of water in soil. Thus, the higher the precipitation the lower is the concentration of chloride in soil solutions. I found that the mineral elements presented similar concentration variations as chloride indicating the strong if not exclusive eect of dilution. The phosphate concentrations were an exception showing irregular variation. Measurement problems due to the low P concentrations, often below the detection limit of the instrument may be the explanation for such irregularities. The variation in chloride-normalized organic components diered from that of chloride. The concentrations of TOC, DON and C : N ratio showed a fairly steep increase with increasing precipitation, especially observable at 15 cm depth in the mineral soil and in some cases also at 30 cm depth. A small TOC consumption by the microbial community during rewetting, a strong microbial TOC production or increased leaching of TOC to the mineral soil are possible explanations for this result. My results demonstrate that the response of inorganic N and P species is mainly driven by concentration/dilution eects while for organic compounds microbial activity in relation to soil moisture was an additional factor controlling the concentrations.
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Keywords: |
hydrochemistry |
Q2 |
ECSF |
mineral N |
nitrogen |
nitrate |
soil solution |
phosphorus |
DOC |
climate change |
Utiger, C. (2013): Der wassergebundene Phosphorkreislauf in einem tropischen Bergwaldökosystem: Konzentrationen, Flüsse und zeitliche Trends Geographisches Institut, Universität Bern, bachelor thesis
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Abstract:
Abstract:
Um das Vorhandensein und den Transport chemischer Elemente auf der Erde zu beschreiben, wird das Konzept der biogeochemischen Kreisläufe angewandt. Ein solches Element ist Phosphor, das wegen seiner Wichtigkeit als limitierendes oder co-limiterendes Element für das Pflanzenwachstum in tropischen Regenwäldern ausgewählt wurde. Am Beispiel eines Einzugsgebietes im tropischen Bergregenwald von Ecuador wird untersucht, wie sich die Phosphorkonzentrationen und Phosphorflüsse entlang des wassergebundenen Kresilaufs vom Freilandniederschlag bis hin zum Oberflächenabfluss sowohl zeitlich wie auch räumlich verhalten. Die untersuchten Daten umfassen die Wasserflüsse und die Konzentrationen von Orthophosphat und totalem gelösten Phosphat zwischen 1998 und 2010 als monatliche Mittel. Die räumliche Verteilung wird mit der Darstellung der Messwerte in Boxplots und der Suche nach räumlichen Mustern analysiert. Um nach saisonalen Prozessen zu suchen, wird einerseits ein lineares Modell, bestehend aus einer Sinus- und einer Cosinus-Funktion gebildet und auf Signfikanz und Aussagekraft, d.h. Erklärung der Variabilität durch das Modell anhang des Anteils an der Gesamtvariation getestet. Anderseits wird die Autokorrelation der Daten auf ein saisonales Muster untersucht. Ein allfälliger langfristiger Trend wird mit dem saisonalen Kendall-Test gesucht. Bei der Analyse der räumlichen Verteilung zeigt sich, dass sich die größten Phosphor-Konzentrationen und -Flüsse zwischen Bestandesniederschlag und organischer Auflage bewegen. Zudem ist der Eintrag durch den Freilandniederschlag größer als der Austrag im Oberflächenabfluss. Bei allen Wasserflüssen wurde eine jährliche Saisonalität festgestellt. Bei den Konzentrationen ist ein antizyklisches Verhalten zu den Wasserflüssen zu erkennen. Der Freilandniederschlag weist keine Saisonalität auf. Die größten Saisonalitäten sind zwischen Krone und organischer Auflage zu finden. Die Konzentrationen in den Saugkerzen und im Oberflächenabfluss sind nur schwach durch saisonale Prozesse geprägt. Bei den Flüssen zeigt nur der Bestandesniederschlag deutlich jährliche Saisonalität. Die Analyse der zeitlichen Trends zeigte keine langfristigen Trends, die auf eine Änderung externer Faktoren zurückzuführen sind. Interne Veränderungen im Pflanzenwachstum könnten für eine Zunahme im Stammabfluss und eine Abnahme der Lysimeterkonzentrationen (unter der organischen Auflage) verantwortlich sein. Bei der Analyse der Feueraktivität als möglicher Quelle für Phosphoreintrag wurden einzelne signifikante Beziehungen mit den Phosphorkonzentrationen gefunden.
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Keywords: |
hydrochemistry |
Q2 |
ECSF |
phosphorus |
seasonality |
temporal trends |
Martinson, G.; Corre, M. & Veldkamp, E. (2012): Responses of nitrous oxide fluxes and soil nitrogen cycling to nutrient additions in montane forests along an elevation gradient in southern Ecuador. Biogeochemistry online , online.
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DOI: 10.1007/s10533-012-9753-9
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Abstract:
Abstract:
Tropical montane forests are commonly limited by N or co-limited by N and P. Projected increases in N deposition in tropical montane regions are thought to be insufficient for vegetation demand and are not therefore expected to affect soil N availability and N2O emissions. We established a factorial Nand P-addition experiment (i.e., N, P, N ? P, and control) across an elevation gradient of montane forests in Ecuador to test these hypotheses: (1) moderate rates of N and P additions are able to stimulate soil-N cycling rates and N2O fluxes, and (2) the magnitude and timing of soil N2O-flux responses depend on the initial nutrient status of the forest soils. Moderate rates of nutrients were added: 50 kg N ha-1 year-1 (in the form of urea) and 10 kg P ha-1 year-1 (in the form of NaH2PO4 . 2H2O) split in two equal applications. We tested the hypotheses by measuring changes in net rates of soil–N cycling and N2O fluxes during the first 2 years (2008??2009) of nutrient manipulation in an oldgrowth premontane forest at 1,000 m, growing on a Cambisol soil with no organic layer, in an old-growth lower montane forest at 2,000 m, growing on a Cambisol soil with an organic layer, and an oldgrowth upper montane rainforest at 3,000 m, growing on a Histosol soil with a thick organic layer. Among the control plots, net nitrification rates were largest at the 1,000-m site whereas net nitrification was not detectable at the 2,000and 3,000-m sites. The already large net nitrification at the 1,000-m site was not affected by nutrient additions, but net nitrification became detectable at the 2,000and 3000-m sites after the second year of N and N + P additions. N2O emissions increased rapidly following N and N ? P additions at the 1,000-m site whereas only smaller increases occurred at the 2,000and 3,000-m sites during the second year of N and N + P additions. Addition of P alone had no effect on net rates of soil N cycling and N2O fluxes at any elevation. Our results showed that the initial soil N status, which may also be influenced by presence or absence of organic layer, soil moisture and temperature as encompassed by the elevation gradient, is a good indicator of how soil N cycling and N2O fluxes may respond to future increases in nutrient additions.
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Keywords: |
phosphorus |
mountain forest |
N2O emissions |
soil N availability |
nutrient manipulation |
nutrient limitation |
wood specific gravity |
aboveground biomass |
environmental gradients |
carbon stocks |
Pilodyn wood tester |