EurekaMag.com logo
+ Site Statistics
References:
53,869,633
Abstracts:
29,686,251
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on LinkedInFollow on LinkedIn

+ Translate

Effects of annual grass senescence on 15NH4+ and 15N-glycine uptake by blue oak (Quercus douglasii) seedlings and soil microorganisms in California oak woodland



Effects of annual grass senescence on 15NH4+ and 15N-glycine uptake by blue oak (Quercus douglasii) seedlings and soil microorganisms in California oak woodland



Soil Biology and Biochemistry 37(3): 551-559



Annual grasses are stronger competitors for available soil N than blue oak seedlings and soil microorganisms. However, little is known about the dynamics of N competition during annual grass senescence. We conducted a field experiment in a California oak woodland to study effects of annual grass senescence on N uptake by grasses, blue oak seedlings and soil microorganisms. Labeled N was applied at the beginning of April, May and of June in the form of 15NH4(+) or 15N-glycine. Plants and soils were harvested after 5 days (15NH4(+) and 15N-glycine treatments) and after 26 days (15NH4(+) treatment only). We evaluated effects of N form, season and labeling period on N competition among oak seedlings, annual grasses and soil microorganisms. N forms did not affect competition among grasses, oak seedlings and soil microorganisms, but more 15N was incorporated into the soil organic N pool in the 15N-glycine treatments than in the 15NH4(+) treatments. There were no seasonal (May vs June) effects on 15N recovery in blue oak seedlings and soil microorganisms. Plant samples from April harvest were lost. In June, when grasses were senescing, more 15N was found in the soil inorganic pool than in May. Extremely dry soils in June may have limited inorganic N availability to oak seedlings and soil microorganisms. After 26-day labeling period, 15N recovery in blue oak seedlings and the soil organic N pool significantly increased, while 15N recovery in both the soil microbial and inorganic N pools decreased compared to the 5-day labeling period. Although blue oak seedling biomass changed little from early May to late June, N concentrations in oak roots increased 53%. In contrast, annual grass biomass peaked in May, and then decreased rapidly. Our results suggest that blue oak seedlings and annual grasses have different temporal competitive abilities. Blue oak seedlings appear to have a long-term strategy for N competition. Blue oaks take up N slowly but steadily, increasing N uptake from 5 to 26 days. This extended time period has a greater positive effect on N uptake than does reduced grass uptake caused by senescence.

(PDF emailed within 0-6 h: $19.90)

Accession: 004131464

Download citation: RISBibTeXText

DOI: 10.1016/j.soilbio.2004.08.017



Related references

Competition for inorganic and organic N by blue oak (Quercus douglasii) seedlings, an annual grass, and soil microorganisms in a pot study. Soil Biology and Biochemistry 36(1): 135-144, 2004

Contrasting seasonal patterns of fine root production for blue oaks (Quercus douglasii) and annual grasses in California oak woodland. Plant and Soil 240(2): 263-274, 2002

Competition for soil water between annual plants and blue oak (Quercus douglasii) seedlings. Oecologia 79(4): 533-541, 1989

Competition for soil water between perennial bunch-grass (Elymus glaucus B.B.) and blue oak seedlings (Quercus douglasii H. & A.). Agroforestry Systems 32(3): 225-235, 1995

Competitive effects of grassland annuals on soil water and blue oak (Quercus douglasii) seedlings. Ecology 74(1): 68-82, 1993

Nitrogen sink strength of ectomycorrhizal morphotypes of Quercus douglasii, Q. garryana, and Q. agrifolia seedlings grown in a northern California oak woodland. Mycorrhiza 18(1): 33-41, 2007

Long-term growth and persistence of blue oak (Quercus douglasii) seedlings in a California oak savanna. Madrono 54(4): 269-274, 2007

Seasonal patterns of nutrient deposition in a quercus douglasii woodland in central california. Plant & Soil 137(2): 209-222, 1991

Lifting and storing bareroot blue oak (Quercus douglasii) seedlings. New Forests 8(2): 89-103, 1994

Release of non-exchangeable 15NH4+ from subgrade, decomposed granite substrates and uptake by non-mycorrhizal and mycorrhizal California native annual grass, Vulpia microstachys. Plant and Soil 300(1 2): 94, 2007

Growth trends of blue oak (Quercus douglasii) in California. Canadian Journal of Forest Research 23(8): 1720-1724, 1993

Historical recruitment of quercus douglasii blue oak in southern california usa. Bulletin of the Ecological Society of America 71(2 SUPPL): 183, 1990

Effect of root pinching on growth patterns of blue oak (Quercus douglasii H. & A.) seedlings. Phyton Horn 34(1): 109-118, 1994

Response of foliar gallotannins to browsing and drought in blue oak quercus douglasii h and a seedlings. Bulletin of the Ecological Society of America 72(2 SUPPL): 144, 1991