Effects of cultural practices on soil respiration in hazelnut orchards and a comparison with an adjacent natural oak forest.

Abstract

Soil respiration (RS) is one of the largest terrestrial sources of CO2 causing global warming and may vary according to land use and vegetation type. Türkiye is in the first place in the world in terms of area of hazelnut orchards that are generally converted from natural forests. The aim of this study was the comparison of the effects of cultural practices (pruning, fertilizing, and pruning+fertilizing) on RS in hazelnut orchards and that of the adjacent natural oak forest. Every trial site had a statistically similar annual mean RS, which ranged from 0.15 to 1.55 g C m-2 day-1. The RS on the sites was different only in the spring season and was similar in the other seasons. The RS of the pruned and fertilized hazelnut orchard (Hpf) in the spring was 58% greater than the unmaintained hazelnut orchard (Hc) and oak forest and 28% greater than the only fertilized hazelnut orchard (Hf). The RS of Hpf was also greater than other sites in most monthly measurements. While the positive correlation between soil moisture and RS was on an annual basis (r = 0.44), it was higher in summer (r = 0.61) and autumn (r = 0.55) seasons. The negative correlation between soil temperature and RS in the summer and autumn seasons evolved positively in winter. The results of the study suggest that the maintenance practices applied in the hazelnut garden could increase RS in the spring when soil moisture and temperature are optimal but have no effect in other seasons or on an annual basis.