Root Nodule Age-Class Transition, Production and Decomposition in an Age Sequence of Alnus nepalensis Plantation Stands in the Eastern Himalayas

Sharma, Eklabya; Ambasht, R. S.

doi:10.2307/2404046

Cited by 25 publications

(15 citation statements)

References 23 publications

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“…In another study (data not shown), living root biomass of poplar decreased earlier in the growing season than living root biomass of alder. In Alnus nepalensis plantations, the time of the year as well as the age of the stand had a significant effect on the rate of mass loss of root nodules of alder (Sharma and Ambasht, 1986). Conditions under the canopy of black alder in our study could have been more conducive to root decomposition later in the growing season.…”

Section: Discussionmentioning

confidence: 61%

Decomposition of roots of black alder and hybrid poplar in short-rotation plantings: Nitrogen and lignin control

1991

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The decomposition of the roots (0-2 mm, 2-5 mm and 5-10 mm) of black alder (Alnus glutinosa (L.) Gaertn.) and hybrid poplar (Populus nigra L. X Populus trichocarpa Torr & Gray) was followed over a 462-day period in pure and mixed plantings in southern Quebec. Small roots of alder had the highest initial concentrations of nitrogen and lignin, and lost 9 and 10% less mass than medium and large roots, respectively. Large roots of poplar had the highest lignin-to-nitrogen ratio and showed the smallest loss of mass over the total incubation period. Slow root decomposition of black alder and hybrid poplar was characterized by a greater proportion of initial root nitrogen immobilized per unit of carbon respired. Lignin concentration in roots of alder and poplar increased rapidly at the beginning of the incubation. Our results suggest that high levels of nitrogen in roots of alder could contribute in slowing the rate of decomposition by allowing the formation of nitrogen-lignin derivatives and low levels of nitrogen in roots of poplar may limit the growth of microorganisms and the rate of root decomposition. A multiple regression was developed using initial nitrogen, lignin concentration and the ratio of lignin to nitrogen to produce an index of the rate of root decomposition. The correlation between the index values and the percentage of residual root mass was significant (r = 0.98, p < 0.01).

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Section: Discussionmentioning

confidence: 61%

Decomposition of roots of black alder and hybrid poplar in short-rotation plantings: Nitrogen and lignin control

1991

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“…root decomposition has apparently not been examined in detail, decomposing A. nepalensis root nodules have been shown to release 95% of their initial N within 10-17 months (Sharma & Ambasht 1986). In contrast, tropical agricultural legumes may lose up to 95% of their initial N within 4 months (Chulan & Waid 1981).…”

Section: Symbiotic Fixationmentioning

confidence: 99%

Sources, fates, and impacts of nitrogen inputs to terrestrial ecosystems: review and synthesis

et al. 1988

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Abstract. The relative importance of nitrogen inputs from atmospheric deposition and biological fixation is reviewed in a number of diverse, non-agricultural terrestrial ecosystems. Bulk precipitation inputs of N (I-12kgN ha-' yr-') are the same order of magnitude as, or frequently larger than, the usual range of inputs from nonsymbiotic fixation (< 1 -5 kg N ha-' yr-I), especially in areas influenced by industrial activity. Bulk precipitation measurements may underestimate total atmospheric deposition by 3040% because they generally do not include all forms of wet and dry deposition. Symbiotic fixation generally ranges from z lo-160 kg N ha-' yr-' in ecosystems where N-fixing species are present during early successional stages, and may exceed the range under unusual conditions.Rates of both symbiotic and nonsymbiotic fixation appear to be greater during early successional stages of forest development, where they have major impacts on nitrogen dynamics and ecosystem productivity. Fates and impacts of these nitrogen inputs are important considerations that are inadequately understood. These input processes are highly variable in space and time, and few sites have adequate comparative information on both nitrogen deposition and fixation.The existing information on N inputs is deficient in several areas: -more intensive studies of total atmospheric deposition, especially of dry deposition, are needed over a wide range of ecosystems; -additional studies of symbiotic fixation are needed that carefully quantify variation over space and time, examine more factors regulating fixation, and focus upon the availability of N and its effects upon productivity and other nutrient cycling processes; -process-level studies of associative N-fixation should be conducted over a range of ecosystems to determine the universal importance of rhizosphere fixation; -further examination of the role of free-living fixation in wood decomposition and soil organic matter genesis is needed, with attention upon spatial and temporal variation; and -investigations of long-term biogeochemical impacts of these inputs must be integrated with process-level studies using modem modelling techniques.

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“…Nodule biomass varies depending on stand age, species composition, tree size, stand density, and soil nutrient concentrations (Binkley 1981(Binkley , 1982Bormann and Gordon 1984;Sharma and Ambasht 1986;Binkley et al 1992;Uliassi and Ruess 2002;Lee and Son 2005;Son et al 2007) and has been estimated to range from 16 to 480 kg ha -1 (Table 1; Binkley 1981;Hurd et al 2001). No clear association has been found between nodule biomass and stand age but nodule biomass tends to increase early until a stand is 10-15 years old (Fig.…”

Section: Nodule Biomass In Alnus Standsmentioning

confidence: 99%

Responses of symbiotic N2 fixation in Alnus species to the projected elevated CO2 environment

Tobita

Yazaki

Harayama

et al. 2015

Trees

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Key message Nitrogen fixation in Alnus species in response to elevated CO 2 may depend on the presence of non-N 2 -fixing tree species in addition to soil conditions. Abstract Alnus is a major genus of actinorhizal plants. Symbiosis with Frankia allows the Alnus species to fix nitrogen (N) at the rate of several to 320 kg N ha -1 year -1 with a nodule biomass of 16-480 kg ha -1 . Alnus species ensures an effective supply of N to soils because of the high N content of leaf litter, rapid decomposition rate, and the influx of herbivorous insects. In addition, the association between regenerated endozoochorous species and Alnus hirsuta suggests that N 2 fixation in Alnus species influences the distribution patterns of regenerated plants as well as improve soil fertility. N 2 fixation by the AlnusFrankia symbiotic relationship may be positively associated with elevated carbon dioxide (CO 2 ) levels. Nodule biomass increased under elevated CO 2 due to enhanced plant growth, rather than changes in biomass allocation. The inhibitory effect of high soil N on nodulation was retained under elevated CO 2 , and the effects of elevated CO 2 on N 2 fixation depended on soil P availability, drought, and many other abiotic and biotic factors. Recent free-air CO 2 enrichment experiments have demonstrated increased N 2 fixation in A. glutinosa exposed to elevated CO 2 in mixed-species stands containing non-N 2 -fixers but not in monocultures, suggesting that N 2 fixation depends on an association with non-N 2 -fixing tree species. Because elevated CO 2 can alter the N and P contents and stoichiometry of plants, it will be necessary to evaluate N allocation and accumulation of biomass when investigating the response of Alnus species to future global climate change.

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Root Nodule Age-Class Transition, Production and Decomposition in an Age Sequence of Alnus nepalensis Plantation Stands in the Eastern Himalayas

Cited by 25 publications

References 23 publications

Decomposition of roots of black alder and hybrid poplar in short-rotation plantings: Nitrogen and lignin control

Decomposition of roots of black alder and hybrid poplar in short-rotation plantings: Nitrogen and lignin control

Sources, fates, and impacts of nitrogen inputs to terrestrial ecosystems: review and synthesis

Responses of symbiotic N2 fixation in Alnus species to the projected elevated CO2 environment

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