EFFECT OF ALDER ON NITROGEN TRANSPORT TO SURFACE WATERS AND CATION LOSSES IN NATURAL ECOSYSTEMS IN ŞiMŞiRLi WATERSHED

Abstract

Plant species compositions in the ecosystem and soils developed under these species compositions cause nutrients to be fixed or transport away from the site. The change of plant species compositions of forest ecosystems in precipitation watersheds changes the quality of water produced from these watershed. Especially, the fact that species such as Alder with nitrogen fixation ability enter into plant species composition will be effective on nutrient cycling. In this study, the effect of Alder on nitrogen transport to surface waters and therefore the cation losses in the ecosystem in stands where it is dominant was investigated. For this purpose, 36 surface water samples from 3 sub-watersheds selected in Şimşirli stream watershed throughout 1 water year and 39 soil samples from 15 soil profiles opened in forest areas were taken. While water quality parameters such as pH, EC, total nitrogen (TN), nitrate (NO₃-N), ammonium (NH₄-N), Ca⁺⁺, Mg⁺⁺, K⁺ and Na⁺ were determined in surface waters, sand, silt, clay, pH, EC, soil organic matter, total nitrogen and exchangeable cations (Ca⁺⁺, Mg⁺⁺, K⁺ and Na⁺) were determined in soil samples. TN and NO₃^-N concentrations in surface waters have increased along with the increase in the rate of forest area in the lower watersheds. Increase of NO₃^-N concentration in surface waters increased the basic cation (Ca⁺⁺, Mg⁺⁺ and K⁺) concentrations. This situation shows that leaching of nitrate in the sub-watersheds increases the cation losses. Annual TN transport in the sub-watersheds varied between 6.17 - 95.09 kg N Ha^-1 and was 44.93 kg N Ha^-1Year^-1 on the average. Findings obtained as a result of the study suggest that Alder might be an important species under the control of the ecosystem and provide valuable information about the possible eutrophication of Galyan-Atasu dam reservoir.

Keywords

• Alder,TN and NO3- export,cation losses,eutrophication

ŞİMŞİRLİ HAVZASINDAKİ DOĞAL EKOSİSTEMLERDE KIZILAĞACIN YÜZEY SULARINA AZOT TAŞINIMI VE KATYON KAYIPLARINA ETKİSİ

Öz

Ekosistemdeki bitki tür bileşimleri ve bu tür bileşimleri altında gelişen topraklar, besinlerin tutulmasına veya ortamdan uzaklaşmasına sebep olurlar. Yağış havzalarındaki orman ekosistemlerinin bitki tür bileşimlerinin değişimi bu havzalardan üretilen suyun kalitesini değiştirir. Özellikle azot bağlama yeteneğine sahip Kızılağaç gibi türlerin bitki tür bileşimine girmesi besin döngüsü üzerinde etkili olacaktır. Bu çalışmada, hakim olduğu meşcerelerde Kızılağacın yüzey sularına azot taşınımı ve dolayısıyla ekosistemdeki katyon kayıplarına etkisi araştırılmıştır. Bu amaçla, Şimşirli dere havzasında seçilen 3 alt havzadan 1 su yılı boyunca 36 adet yüzey suyu örneği ile orman alanlarında açılan 15 toprak profilinden 39 adet toprak örneği alınmıştır. Yüzey sularında pH, EC, toplam azot (TN), nitrat (NO3-N), amonyum (NH4N), Ca++, Mg++, K+ve Na+ gibi su kalite parametreleri, toprak örneklerinde kum, toz, kil, pH, EC, organik madde, toplam azot ve değişebilir katyonlar (Ca++, Mg++, K+ ve Na+) belirlenmiştir. Alt havzalardaki orman alanı oranının artmasıyla birlikte yüzey sularındaki TN ve NO3-N konsantrasyonları artmıştır. Yüzey sularındaki NO3-N konsantrasyonunun artması bazik katyon (Ca++, Mg++ ve K+) konsantrasyonlarını artırmıştır. Bu durum alt havzalardaki nitrat yıkanmasının katyon kayıplarını arttırdığını göstermektedir. Alt havzalardaki yıllık TN taşınımı 6.17 - 95.09 kg N Ha-1 arasında değişmekte ve ortalama 44.93 kg N Ha-1Yıl-1'dır. Çalışma sonucunda elde edilen bulgular, ekosistem kontrolünde Kızılağacın önemli bir tür olabileceği ve GalyanAtasu barajı göletinin muhtemel ötrofikasyonu hakkında değerli bilgiler verebilir.

Anahtar Kelimeler

• Kızılağaç, TN ve NO3 - taşınımı, katyon kayıpları, ötrofikasyon

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