Using Soil Stable Isotopes, δ13c and δ15n, Properties for Interpreting Effects of Forest Understory Vegetation Removal on Nutrient Cycling

Yıl 2019, Cilt: 15 Sayı: 2, 96 - 105, 31.12.2019

Oktay Yıldız

Öz

Forest harvesting and understory vegetation management may disturb the ecological integrity of forest ecosystems. Abrupt change in plant composition in the stand also modifies the nutritional status of the site. The aim of this study is to analyze the soil stable isotopes, δ13C and δ15N properties for interpreting effects of clearing understory vegetation on nutrient cycling. The study utilized a previous project in which the understory vegetation was variably cleared in Douglas-fir plantations situated in the Pacific Coast of Oregon, USA. Treatments included removing brush and herbaceous vegetation control at varying ratios. Also, a control plot was included in the experiment where no vegetation removal (DFC) was employed. On one of the plots, shrubs were completely cleared, leaving only herbs and Douglas-fir (DFH). Another plot received complete removal of shrubs and herbs, leaving only Douglas-fir (DFO). Soil samples were collected on each plot at 5th and 15th year of the stand establishment. Soil was sub-sampled to distinguish light (LF)- and heavy-fraction (HF) organic material. The stable isotopes 13C and 15N of the LF and HF were analyzed for their 13C and 15N stable isotope values. Complete understory vegetation removal significantly enriched soil δ15N on DFO sites at age 5. The presence of understory vegetation had significant effects on organic matter decomposition and soil nutrient cycling.

Anahtar Kelimeler

Stable isotopes, Carbon, Nitrogen, Soil organic matter, Vegetation removal

δ13C ve δ15N Durağan Izotoplar Aracılığıyla Diri Örtü Kontrolünün Besin Döngüsüne Etkisinin Belirlenmesi

Öz

Kesim ve diri-örtü kontrolü orman ekosistemlerinin ekolojik bütünlüğünü tahrip edebilmektedir. Meşçere bitki kompozisyonundaki ani değişiklik sahanın besin durumunu da değiştirmektedir. Bu çalışmanın amacı δ13C ve δ15N durağan izotoplarından yararlanarak orman ekosisteminde diri örtü kontrolünün besin döngüsüne etkisini belirlemektedir. Çalışmada ABD’nin Oregon eyaletinin Pasifik kıyısında bulunan Duglas göknarı ağaçlandırma sahalarında daha önce gerçekleştirilen farklı yoğunlukta diri örtü kontrol çalışmasından yararlanılmıştır. İşlemler farklı yoğunlukta çalı ve otsu türlerin sahadan uzaklaştırılmasını içermektedir. Kontrol ünitesinde diri örtü olduğu gibi bırakılmıştır (DFC). Bir deneme ünitesinde, çalı türleri uzaklaştırılmış ve sahada Duglas göknarı ağaçları ile otsu türler bırakılmıştır (DFH). Bir başka deneme ünitesinde, bütün diri örtü uzaklaştırılmış ve sadece Duglas göknarı fidanları bırakılmıştır (DFO). Ağaçlandırmanın 5. ve 15. yılında her deneme ünitesinden toprak örneklemeleri yapılmıştır. Toprak örneklerinden alt örneklemeler alınarak içerisindeki organik maddenin hafif (LF) ve ağır (HF) fraksiyonlarına ayrılması sağlanmıştır. Daha sonra LF ve HF’nin 13C ve 15N durağan izotop içerikleri belirlenmiştir. Denemenin beşinci yılında diri örtünün tamamının uzaklaştırıldığı DFO deneme ünitesinde toprağın δ15N bakımından zenginleştiği belirlenmiştir. Diri örtünün sahada bırakılmasının organik madde ayrışmasında ve besin döngüsünde etkili olduğu ortaya çıkmıştır. 

Anahtar Kelimeler

Durağan izotop, Karbon, Azot, Toprak organik maddesi, Diri örtü kontrolü

Kaynakça

• Ågren, G.I., Bosatta, E., Balesden, J. 1996. Isotope Discrimination during Decomposition of Organic Matter: A Theoretical Analysis. Soil Science Society of America Journal. 60 (4): 1121-1126.Bailey, J.D., Mayrsohn, C., Doescher, P.S., Pierre, E.S., Tappeiner, J.C., II. 1998. Understory vegetation in old and young Douglas-fir forests of western Oregon. For. Ecol. and Management, 112: 289-302.Barnes, B. V., Zak, D. R., Denton, S. R., Spurr, S.H. 1998. Forest Ecology. 4th ed. John Wiley & Sons, Inc. New York.Blake, J. R., Hartge, K. H. 1986. Bulk density. In Methods of soil analysis. Part 1. Edited by A. Klute. SSSA book series. 5. ASA and SSSA, Madison, WI. 363-375.Bormann, B.T., Cromack, K.,Jr., Russell, W.O., IIl. 1994. The influence of red alder on soils and long-term ecosystem productivity. In The biology and management of red alder. Edited by D.E. Hibbs, D.S. DeBell and R.F. Tarrant. Oregon State University Press, Corvallis.Bormann, F.H., Likens, G.E. 1979. Pattern and process in a forested ecosystem. Springer-Verlag, New York.Brady, N.C., Weil, R.R. 1999. The nature and property of soils. 12th ed. Prentice-Hall, Upper Saddle River, New Jersey.Christensen, B.T. 1992. Physical fractionation of soil and organic matter in primary particle size and density separates. Springer-Verlag, New York. Adv. Soil Science, 20: 1-90.Cromack, K., Jr., Miller, R. E., Helgerson, O. T., Smith, R.B., Anderson, H.W. 1999. Soil carbon and nutrients in a coastal Oregon Douglas-fir plantation with red alder. Soil Science Society. American Journal, 63: 232-239.Ehleringer, J.R., Field, C.B., Lin, Z., Kuo, C. 1986. Leaf carbon isotope and mineral composition in subtropical plants along an irradiance cline. Oecologia, 70: 520-526. Harrington, T.B., Tappeiner, J.C.,II. 1997. Growth responses of young Douglas-fir and tanoak 11 years after various levels of hardwood removal and understory suppression in southwestern Oregon, USA. Forest Ecology and Management. 96(1):11.Hogberg, P. 1997. 15N natural abundance in soil-plant systems. New Phytology. 137: 179-203.Jensen, E.C., and Anderson, D.J., Zasada, J.C., Tappeiner, J.C.,II. 1995. The reproductive ecology of broadleaved trees and shrubs: Salmonberry (Rubus spectabilis Pursh). Forest Research Laboratory, Oregon State University, Corvallis. Research Publication, 9,7Jobidon, R. 2000. Density-dependent effects of northern hardwood competition on selected environmental resources and young white spruce (Picea glauca) plantation growth, mineral nutrition, and stand structural development - a 5-year study. Forest Ecology and Management, 130: 77-97. Kimmins, J.P. 1996. Importance of soil and role of ecosystem disturbance for sustained productivity of cool temperate and boreal forests. Soil Science Society American Journal, 60: 1643-1654.Knowe, S.A., Harrington, T.B., Shula, R.G. 1992. Incorporating the effects of interspecific competition and vegetation management treatments in diameter distribution for Douglas-fir saplings. Canadian Journal of Forest Research, 22: 1255-1262.Krull, E.S., Bestland, E.A., Gates, W.P. 2002. Soil organic matter decomposition and turnover in a tropical ultisol: Evidence from δ13C, δ15N and geochemistry. Radiocarbon, 44 (1): 93–112Mao, D.M., Min, Y.W., Yu, L. L., Martens, R., Insam, H. 1992. Effects of afforestation on microbial biomass and activity in soils of tropical China. Soil Biology and Biochemistry, 24: 865-877.Marks, P.L., Bormann, F.H. 1972. Revegetation following forest cutting: mechanisms for the return to steady state nutrient cycling. Science, 176: 914-915.Nadelhoffer, K.J., Fry, B. 1988. Controls on natural nitrogen-15 and carbon-13 abundances in forest soil organic matter. Soil Science Society of American Journal. 52: 1633-1640. Newton, M., Preest, D. S. 1988. Growth and water relations of Douglas-fir seedlings under different weed control regimes. Weed Science, 36: 653-662.Paul, E.A., Clark, F.E. 1996. Soil microbiology and biochemistry. Academic Press, 2nd ed., New York.Perry, D. A. 1988. An overview of sustainable forestry. Journal of Pesticide Reform, 8: 8-12.SAS systems for windows. 1996. Release 6.12. SAS Institute Inc. Cary, North Carolina.Sea, D. S., Whitlock, C. 1995. Postglacial vegetation and climate of the Cascade Range, Central Oregon. Quaternary Research, 43: 370- 81.Sollins, P., Spycher, G., Glassman, C.A. 1984. Net nitrogen mineralization from light- and heavy-fraction forest soil organic matter. Soil Biology and Biochemistry, 16: 31-37.Spies, T.A., Ripple, W.J., Bradshaw, G.A. 1994. Dynamics and pattern of a managed coniferous forest landscape in Oregon. Ecological Applications, 4: 555 -568.Stevenson, F.J. 1986. Cycles of soil, carbon, nitrogen, phosphorus, sulfur, and micronutrients. John Wiley and Sons, Inc. New York.Strickland, T.C., Sollins, P. 1987. Improved method for separating light- and heavy-fraction organic material from soil. Soil Science Society of American Journal, 51: 1390-1393.Tesch, S.D., Korpela, E.J., Hobbs, S.D. 1993. Effects of sclerophyllous shrub competition and root and shoot development and biomass partitioning of Douglas-fir seedlings. Canadian Journal of Forest Research, 23: 1415-1426.Tiessen, H., Cueva, E., Chacon, P. 1994. The role of soil organic matter in soil fertility. Nature, 371: 783-785. Tiunov, A.V. 2007. Stable Isotopes of Carbon and Nitrogen in Soil Ecological Studies. Biology Bulletin, 34 (4): 395–407 Wagner, R.G. 1989. Interspecific competition in young Douglas-fir plantations of the Oregon Coast Range, Ph.D. Dissertation, Oregon State University, Corvallis.Wagner, R.G., Radosevich, S. R. 1989. Neighborhood predictors of interspecific competition in young Douglas-fir plantations. Canadian Journal of Forest Research, 21: 821-828. Walstad, J.D., Kuch, P.J. 1987. Introduction to forest vegetation management. In Forest vegetation management for conifer production. Edited by J.D. Walstad and P.J. Kuch. John Wiley and Sons, New York, 3-14.Waring, R. H., Franklin, J. F. 1979. Evergreen coniferous forests of the Pacific Northwest. Science, 204: 1380-1386.Waring, R. H., Running, S. W. 2000. Forest ecosystems: Analysis at multiple scales. 3rd ed. Academic Press. San Diego. Wild, A.1988. Russell's soil conditions and plant growth. 11th ed. Longman Scientific and Technical, Essex, England.Wu, Y., Wang, B., Chen, D. 2018. Regional-scale patterns of δ13C and δ15N associated with multiple ecosystem functions along an aridity gradient in grassland ecosystems. Plant Soil, 432: 107–118.Yildiz, O., Cromack Jr, K., Radosevich, S.R ., Martinez-Ghersa, MA., Baham, JE. 2011. Comparison of 5th-and 14th-year Douglas-fir and understory vegetation responses to selective vegetation removal. Forest Ecology and Management. 262(4): 586-597.