Decomposition and nitrogen release from decomposing woody roots in coniferous forests of the Pacific Northwest: a chronosequence approach

Cai, Hua; Harmon, Mark E.; Griffiths, Robert P.

doi:10.1139/x00-167

Cited by 78 publications

(36 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, in longer term from ecological perspective, the decay roots may turn into organic substance, contributing to plant nutrients and improving soil fertility for sustainable growth of tree. This would help maintain the nutrient cycle in soil and ecology (Ostertag and Hobbie, 1999;Chen et al, 2001). In the future, the observed changes in ks or infiltration rate due to different plant spacing can be verified using in-situ double-ring 25 infiltration tests (such as those conducted by Leung et al (2015a)), which might give a better indication than tests on small laboratory samples obtained from cores.…”

Section: Discussionmentioning

confidence: 99%

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Leung

et al. 2017

Can. Geotech. J.

View full text Add to dashboard Cite

Investigation of plant growth and transpiration-induced matric suction under mixed grass-tree conditions Ni, J. J.; Leung, Anthony; Ng, C. W. W.; So, P. S. General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain.• You may freely distribute the URL identifying the publication in the public portal. Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractAlthough evapotranspiration-induced matric suction for single species has been widely studied, little is known about how mixed-species planting would affect the plant growth and induced matric suction. This study aims to explore the effects of grass-tree interaction on their growth and induced matric suction during evapotranspiration (ET) and rainfalls. Field monitoring was carried out to measure matric suction responses in compacted soil that was vegetated with (i) single tree species, Schefflera heptaphylla and (ii) mixed species of the trees and a grass species, Cynodon dactylon. In each condition, three tree spacings (120, 180 and 240 mm) were planted. When tree spacing increased from 120 to 240 mm, the peak tree root area index (RAI, for fine roots with diameter < 2 mm) decreased by 16%, but the peak grass RAI increased by 29%. At mixed planting plots, the ET-induced peak matric suction for tree spacing of 240 mm was 20% higher than that for spacing of 180 mm because of increased contribution of grass root-water uptake as the trees were more widely spaced. Without grass, a reverse trend was observed as tree-tree interaction reduced at wide spacings. The peak ET-induced matric suction had a significant linear correlation with RAI. During rainfalls, the highest matric suction was preserved for the case of 240 mm spacing due to the greatest reduction of soil hydraulic conductivity by roots.

show abstract

Section: Discussionmentioning

confidence: 99%

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Leung

et al. 2017

Can. Geotech. J.

View full text Add to dashboard Cite

show abstract

“…The analysis showed that initial tissue chemistry explained the greatest proportion of variance in decomposition rate (85%), while environmental variables, most notably temperature, precipitation and actual evapotranspiration (AET) played a secondary role. Since Silver and Miya's analysis, fine root decomposition studies have largely focused on the effects of litter quality on rate of decay and generally support the notion that litter quality regulates microbial activity and thus decomposition (Chen et al 2001;Lemma et al 2007). In general, decay rates of fine roots are positively correlated with initial concentrations of Ca, Mg, Mn, N and P and negatively correlated with C:N, lignin:N, cellulose, and phenolic compounds including tannins, and lignin (Berg et al 1998;John et al 2002;Jalota et al 2006;Wang et al 2010;Tong et al 2012;García-Palacios et al 2016;Guerrero-Ramírez et al 2016;Roumet et al 2016).…”

Section: Factors That Influence Fine Root Decompositionmentioning

confidence: 95%

Maintaining connectivity: understanding the role of root order and mycelial networks in fine root decomposition of woody plants

Beidler

Pritchard

2017

Plant Soil

View full text Add to dashboard Cite

Background The predictive power of climate models is limited by an incomplete understanding of the controls on fine root decomposition and thus belowground carbon cycling. To more accurately model rates of decay, fine root heterogeneity needs to be addressed in fine root decomposition studies. Branching order integrates both structural and chemical properties that are important in indicating litter quality and decay rate. Scope We discuss current views on the controls and patterns of fine root decomposition in combination with recent findings related to the effects of branching order and mycorrhizal decomposition. We examine the counterintuitive finding that nitrogen rich, lower order roots decompose more slowly than woody, higher order roots in temperate and subtropical forests. ConclusionsWe posit that slower decomposition of first and second compared to higher order roots might be caused by the poor carbon quality associated with higher concentrations of phenols in lower order roots or by inhibition of saprophytes by the mycorrhizal fungi that often preferentially inhabit these roots. Alternatively, apparent recalcitrance of lower order roots could be an experimental artifact caused by severing pre-mortem mycelial connections during sample processing, or exclusion of animals that graze fungal structures by the small mesh sizes characteristic of litterbags. To better predict the residence time of the carbon contained in the entire fine root pool, existing methods should be applied to individual root orders when practical. New methods for characterizing decomposition of undisturbed roots that have senesced naturally are greatly needed.

show abstract

“…Root decomposition is closely related to root turnover, which has been shown to be highly variable depending on tree species and also on sitespecific and climatic conditions (Finer et al, 2011;Brunner et al, 2012). We assessed this uncertainty by calculating the root decay for different decomposition rates as given by Ngao et al (2007) and Chen et al (2001). The calculated fine-root mass loss was 25 % of the initial mass for the first year after trenching.…”

Section: Approach 2: On the Indirect Quantification Of The Neementioning

confidence: 99%

A fertile peatland forest does not constitute a major greenhouse gas sink

et al. 2013

View full text Add to dashboard Cite

Abstract. Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with high organic matter content. However, the carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we determined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO 2 exchange (NEE) were applied, for the year 2008, one direct (eddy covariance) and the other indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.3 ± 3.9 t C ha −1 yr −1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was probably in its phase of maximum C assimilation or shortly past it. The N 2 O fluxes were determined by the closed-chamber technique and amounted to 0.9 ± 0.8 t C eq ha −1 yr −1 . According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −1.2 ± 0.8 t C eq ha −1 yr −1 . This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 0.6 ± 4.5 t C eq ha −1 yr −1 . Irrespective of the approach applied, the soil CO 2 effluxes counter large amounts of the C sequestration by trees. Due to accumulated uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the rate of C sequestration will likely decrease with forest age, the site will probably become a GHG source once again as the trees do not compensate for the soil C and N losses. Also forests in younger age stages have been shown to have lower C assimilation rates; thus, the overall GHG sink potential of this afforested nutrient-rich organic soil is probably limited to the short period of maximum C assimilation.

show abstract

Decomposition and nitrogen release from decomposing woody roots in coniferous forests of the Pacific Northwest: a chronosequence approach

Cited by 78 publications

References 29 publications

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Maintaining connectivity: understanding the role of root order and mycelial networks in fine root decomposition of woody plants

A fertile peatland forest does not constitute a major greenhouse gas sink

Contact Info

Product

Resources

About