Fine Root Distribution in a Lower Montane Rain Forest of Panama

Hölscher, Dirk; Dunker, Bianca; Harbusch, Marco; Corre, Marife D.

doi:10.1111/j.1744-7429.2009.00492.x

Cited by 11 publications

(8 citation statements)

References 27 publications

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“…*p < 0.05; **p < 0.01; significant correlations are indicated in bold ferns constituted the understorey layer (Hansson et al 2011). In addition, our findings in the BF were similar to those of Hölscher et al (2009), who recorded a fine root biomass (including understorey vegetation) of 198 g m −2 in the litter layer and the upper mineral soil (0-10 cm depth) in a lower montane rainforest of Panama. However, we found the fine root biomass between the surface and 15 cm soil depth to be greater than that reported for the roots of herbs in naturally regenerated beech, silver birch, and Scots pine woodlands in France (Curt and Prévosto 2003).…”

Section: Discussionsupporting

confidence: 73%

Understorey fine root mass and morphology in the litter and upper soil layers of three Chinese subtropical forests

Wang

et al. 2016

Plant Soil

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Aims To quantitatively assess how fine root biomass and necromass of understorey species vary in the litter and upper mineral soil layers. Methods The method combines in situ sampling of the litter layer with sequential coring during the root growth stage in three Chinese subtropical forests: coniferous forest, coniferous and broad-leaved mixed forest, and evergreen broad-leaved forest. Results Approximately 67-74 % of the total fine root mass occurred in the layer of decomposing litter (L2) and that of the top 7.5 cm of the soil (M1). Layer L2 was the preferential horizon for fine root growth, and the thickness of this horizon strongly affected the vertical fine root pattern. In addition, the fine root mass was positively correlated with total N concentration in layers L2 and M1. For all three forest types, most fine roots had diameters <1 mm and clear decreasing trends in specific (mass-based) root length and tip number were observed from the litter layer to the soil and the N concentration of live roots also decreased with depth. Conclusions Understorey roots show a soil exploitation pattern through which absorptive fine roots are arranged to maximize nutrient acquisition from the litter and upper soil layers and to avoid belowground competition with trees, especially in species-rich forests.

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Section: Discussionsupporting

confidence: 73%

Understorey fine root mass and morphology in the litter and upper soil layers of three Chinese subtropical forests

Wang

et al. 2016

Plant Soil

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“…A dense root mat takes up N directly from litter in the O horizon (Sayer et al 2006) and prevents soil microbes from accessing NH 4 + (Chandler 1985). Thus, a superficial root mat retains N through plant uptake in these ecosystems (Stark and Jordan 1978;Hölscher et al 2009), resulting in a tight N cycle (Tobón et al 2004). In contrast, deeper root systems are generally believed to provide a safety-net service by expanding the soil volume accessible for taking up mobile nutrients, such as NO 3 -, leached from the topsoil with a low nutrient retention capacity (Maeght et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen flux patterns through Oxisols and Ultisols in tropical forests of Cameroon, Central Africa

Shibata

Sugihara

Mvondo-Zé

et al. 2017

Soil Science and Plant Nutrition

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We lack an understanding of nitrogen (N) cycles in tropical forests of Africa, although the environmental conditions in this region, such as soil type, vegetation, and climate, are distinct when compared with other tropical forests. Herein, we simultaneously quantified N fluxes through precipitation, throughfall, and 0-, 15-, and 30-cm soil solutions, as well as litterfall, in two forests with different soil acidity (Ultisols at the MV village (exchangeable Al 3+ in 0-30 cm, 126 kmol c ha -1 ) and Oxisols at the AD village (exchangeable Al 3+ in 0-30 cm, 59.8 kmol c ha -1 )) over 2 years in Cameroon. The N fluxes to the O horizon via litterfall plus throughfall were similar for both sites (MV and AD, 243 and 273 kg N ha -1 yr -1 , respectively). Those values were remarkably large relative to other tropical forests, reflecting the dominance of legumes in this region. The total dissolved N flux from the O horizon at the MV was 28 kg N ha -1 yr -1 , while it was 127 kg N ha -1 yr -1 mainly as NO 3 --N (~80%) at the AD. The distinctly different pattern of N cycles could be caused by stronger soil acidity at the MV, which was considered to promote a superficial root mat formation in the O horizon despite the marked dry season (fine root biomass in the O horizon and its proportion to the 1-m-soil profile: 1.5 Mg ha -1 and 31% at the MV; 0.3 Mg ha -1 and 9% at the AD). Combined with the published data for N fluxes in tropical forests, we have shown that Oxisols, in combination with N-fixing species, have large N fluxes from the O horizon; meanwhile, Ultisols do not have large fluxes because of plant uptake through the root mat in the O horizon. Consequently, our results suggest that soil type can be a major factor influencing the pattern of N fluxes from the O horizon via the effects of soil acidity, thereby determining the contrasting plant-soil N cycles in the tropical forests of Africa. ARTICLE HISTORY

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“…Given that organic layers of tropical montane forests are reported to store large amounts of potentially mineralizable nutrients (Wilcke et al 2002), the root proliferation in the organic layer in our montane site (accounting for 41% of the total fine-root mass within 1 m depth; Ho¨lscher et al 2009) is possibly a response to this large pool of nutrients. The added N may have favored C assimilation by microbes resulting in increased microbial biomass which, in turn, resulted in a positive feedback by increased mineralization of nutrients stored in the organic layer and consequently increased plant-derived inputs (i.e., increased leaf litterfall by 1-2 yr N addition to our montane site; Appendix A; ).…”

Section: Effects Of N Addition On Soil-n Cycling and Losses In The Lomentioning

confidence: 99%

Impact of elevated N input on soil N cycling and losses in old‐growth lowland and montane forests in Panama

Corre

Veldkamp

Arnold

et al. 2010

Ecology

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205

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Abstract. Nitrogen deposition is projected to increase rapidly in tropical ecosystems, but changes in soil-N-cycling processes in tropical ecosystems under elevated N input are less well understood. We used N-addition experiments to achieve N-enriched conditions in mixedspecies, lowland and montane forests in Panama. Our objectives were to (1) assess changes in soil mineral N production (gross rates of N mineralization and nitrification) and retention (microbial immobilization and rapid reactions to organic N) during 1-and 9-yr N additions in the lowland forest and during 1-yr N addition in the montane forest and (2) relate these changes to N leaching and N-oxide emissions.In the old-growth lowland forest located on an Inceptisol, with high base saturation and net primary production not limited by N, there was no immediate effect of first-year N addition on gross rates of mineral-N production and N-oxide emissions. Changes in soil-N processes were only apparent in chronic (9 yr) N-addition plots: gross N mineralization and nitrification rates, NO 3 À leaching, and N-oxide emissions increased, while microbial biomass and NH 4 þ immobilization rates decreased compared to the control. Increased mineral-N production under chronic N addition was paralleled by increased substrate quality (e.g., reduced C:N ratios of litterfall), while the decrease in microbial biomass was possibly due to an increase in soil acidity. An increase in N losses was reflected in the increase in 15 N signatures of litterfall under chronic N addition.In contrast, the old-growth montane forest located on an Andisol, with low base saturation and aboveground net primary production limited by N, reacted to first-year N addition with increases in gross rates of mineral-N production, microbial biomass, NO 3 À leaching, and Noxide emissions compared to the control. The increased N-oxide emissions were attributed to increased nitrification activity in the organic layer, and the high NO 3 À availability combined with the high rainfall on this sandy loam soil facilitated the instantaneous increase in NO 3 À leaching. These results suggest that soil type, presence of an organic layer, changes in soil-N cycling, and hydrological properties are more important indicators than vegetation as an N sink on how tropical forests respond to elevated N input.

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Fine Root Distribution in a Lower Montane Rain Forest of Panama

Cited by 11 publications

References 27 publications

Understorey fine root mass and morphology in the litter and upper soil layers of three Chinese subtropical forests

Understorey fine root mass and morphology in the litter and upper soil layers of three Chinese subtropical forests

Nitrogen flux patterns through Oxisols and Ultisols in tropical forests of Cameroon, Central Africa

Impact of elevated N input on soil N cycling and losses in old‐growth lowland and montane forests in Panama

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