Seasonal changes in microbial biomass carbon (Cmic), nitrogen (Nmic), phosphorus (Pmic), and microbial respiration of forest floor and top soil under beech, fir and mixed fir-beech forest stands

Mikrobiyal biyokütle toprak ile bitki arasındaki bağlantıyı sağlayan çok önemli bir parametredir. Bu yüzden toprak mikrobiyal biyokütlesi ve faaliyeti son zamanlarda toprak sağlığı ve kalitesinin değerlendirilmesinde kullanılan hassas bir gösterge olarak karşımıza çıkmaktadır. Organik maddenin biyolojik olarak aktif bölümünü oluşturan mikrobiyal biyokütle C, N ve P'un ölçülmesi toprak kalitesi ve verimliliğinde meydana gelen değişimi en güzel bir şekilde yansıtmaktadır. Bu çalışmada, mevsimsel değişeme bağlı olarak farklı meşcereler altındaki ölü örtü (yaprak, çürüntü ve humus) ve üst topraktaki (0-5 cm) organik madde ve besin döngüsünde toprak mikrobiyal biyokütlesinin rolünü anlamak, ağaç türlerinin mikrobiyal biyokütle üzerine olan etkilerini ortaya koyabilmek ve bazal solunum ölçümleri yapılarak mikrobiyal faaliyetlerin meşcere tiplerine ve mevsime bağlı değişimini belirlemek hedeflenmiştir. Ayrıca mikrobiyal biyokütle C, N, P ve bazal solunum ile ölü örtü ve toprak örneklerinin diğer bazı özellikleri arasındaki ilişkilerin ortaya konulması amaçlanmıştır. Doğu kayını (Fagus orientalis Lipsky), Uludağ göknarı (Abies nordmanniana subsp. bornmülleriana Mattf.) ve göknar-kayın karışık meşcerelerinin doğal yayılış alanı olan Bartın ili Arıt ilçesi çalışma alanı olarak seçilmiştir. Ölü örtü ve üst toprakların mikrobiyal biyokütle C, N ve P içerikleri kloroform fumigasyon ekstraksiyon yöntemi ile, mikrobiyal faaliyet ise bazal solunum ölçümü yapılarak belirlenmiştir. Basit varyans analizi sonuçlarına göre ölü örtü ve toprak örneklerinin mikrobiyal biyokütle C, N ve P içerikleri ile mikrobiyal solunum (bazal solunum) meşcere tiplerine ve mevsimlere göre değişiklik göstermektedir. Göknar meşceresi ölü örtü solunumları hariç, genel olarak mikrobiyal biyokütle ve solunum, göknar meşceresinde diğer meşcerelere göre daha yüksek, ilkbahar ve kış mevsimlerinde ise yaz ve sonbahar mevsimlerine göre daha düşük olarak tespit edilmiştir. Ayrıca, korelasyon analizi sonucuna göre mikrobiyal biyokütle C, N, P içerikleri ile mikrobiyal solunum, ölü örtü ve toprak örneklerinin nem içeriği, sıcaklık, organik C, bitkiye yarayışlı P gibi diğer bazı fiziksel ve kimyasal özellikleri arasında da istatistiki anlamda ilişki ortaya çıkmıştır. Yapılan bu çalışma ile aynı yetişme ortamında bulunan farklı meşcere tiplerine ait ölü örtü ve üst toprakların bazı fiziksel, kimyasal ve biyolojik özelliklerinin birbirinden farklı olduğu ve mevsimlere göre de değişiklik gösterdiği ortaya çıkmıştır. Farklı meşcerelere ait ölü örtü ve üst toprakların mikrobiyal biyokütle ve solunumları, organik C, toplam N ve bitkiye yarayışlı P tarafından kontrol edildiği tespit edilmiştir. Ayrıca, mikrobiyal biyokütle ve solunumun pH, kil içeriği gibi diğer ölü örtü ve toprak özellikleri ile nem içeriği, sıcaklık gibi çevresel faktörlerden de etkilendiği belirlenmiştir. Diğer taraftan bu çalışmada elde edilen veriler ölü örtü ve toprakların mikrobiyal biyokütle ve faaliyetinde gelecekte ortaya çıkabilecek değişiklikleri izlemede karşılaştırmalı olarak kullanılabilecektir.Microbial biomass is a significant parameter that supplies the linkage between the soil and the plant. Therefore soil microbial biomass and activity are the sensitive bioindicators for the determination of the soil health and quality in the recent years. Measurement of the biologically active fractions of the soil organic matter, such as microbial biomass C, N and P could better reflect changes in the soil quality and productivity. In this study, based on the seasonal changes, discovering the role of the soil microbial biomass on the organic matter and nutrient cycle at the forest floor (litter, fermentation and humus) and top soil (0-5 cm) under various stands are targeted. Besides, the determination of the tree species impact on the microbial biomass and the assessment of the change in the microbial activities relative to the stand types and seasons by conducting basal respiration measurements are aimed. The statement of the relationships between microbial biomass C, N, P, basal respiration and some other characteristics of the forest floor and soil samples is also purposed. The Arıt District of the Bartın Province which are the natural habitat for the Oriental beech (Fagus orientalis Lipsky), Bornmullerian fir (Abies nordmanniana subsp. bornmülleriana Mattf.) and the fir-beech mixed stands were chosen as the study area. The microbial biomass C, N and P content of the forest floor and top soil was determined based on the chloroform fumigation extraction method and the microbial activity was investigated based on the basal respiration measurement. According to the results of the simple variance analysis (One-Way ANOVA), the microbial biomass C, N and P content of the forest litter and top soil and the microbial respiration (basal respiration) changes relative to the stand type and the seasons. Except the forest floor respiration, generally, the microbial biomass and respiration is the highest under the fir stand compared to other stands and lower for the spring and winter compared to the summer and autumn. Furthermore, according to the results of the correlation analysis, there is a statistical correlation between the microbial biomass C, N and P content, microbial respiration, moisture content of the forest floor and top soil samples, temperature, organic C, plant available P and some other physical and chemical properties. According to the results of this study, some physical, chemical and biological properties of the forest floor and top soil samples under different stands at the common habitat are different from each other and differ relative to the seasons. The microbial biomass and respiration of forest floor and top soil samples under different stands are controlled by the organic C, total N, plant available P. Moreover, the microbial biomass and respiration is influenced by the other forest floor and soil properties such as pH, clay content and by the environmental factors such as moisture content and temperature. On the other hand, the data of this study are able to be utilized comparatively for monitoring the possible future changes in the microbial biomass and activity of the forest floor and soil

Microbial biomass, basal respiration, and microbial indices of soil in diverse croplands in a region of northwestern Turkey (Bartin)

Legumes are very important both ecologically and agriculturally, as well as economically since soil quality can be improved by the added nitrogen and increased organic matter content they provide. It can be advantageous to apply quantitative methods to indicate soil quality using a dataset of soil characteristics that includes microbial biomass content and activity. The Western Black Sea Region of Turkey was chosen as the study area with the aim of determining the variations in the soil characteristics (physical, chemical, and microbiological) in diverse croplands. At the sites sampled, marked differences were found in the bulk density, clay, soil temperature, soil moisture content, organic carbon, total N, C-org/N-total ratio, and microbial characteristics of vetch (Vicia sativa L.), alfalfa (Medicago sativa L.), and sainfoin (Onobrychis sativa L.) croplands. There was a significant increase (P < 0.05) in the microbial biomass carbon content in the alfalfa (709.27 mu g g(-1)) and sainfoin (607.22 mu g g(-1)) croplands compared with the vetch (558.07 mu g g(-1)) cropland. Microbial biomass nitrogen was significantly lower in the vetch (103.67 mu g g(-1)) cropland compared with that in the sainfoin (127.42 mu g g(-1)) and alfalfa (140.26 mu g g(-1)). The highest basal respiration was determined in the alfalfa (1.09 mu g CO2-C g(-1) soil h(-1)) cropland, while the lowest was found in the vetch (0.54 mu g CO2-C g(-1) soil h(-1)) cropland. The mean C-mic/C-org percentage of the soils was lower in the sainfoin cropland when compared with the other croplands; however, statistically, no difference (P > 0.05) was observed among them. The soil under Onobrychis sativa L. and Vicia sativa L. exhibited the highest (1.67 mg CO2-C g(-1) C-mic h(-1)) and lowest (1.03 mg CO2-C g(-1) C-mic h(-1)) mean metabolic quotients (qCO(2)), respectively. When the microbial biomass carbon and nitrogen were taken into account, the high qCO(2) values may have been an indication that the microbial biomass of decomposed organic compounds was more active, rather than signifying a result of metabolic stress. Consequently, it can be said that the variations found in the metabolic quotient, basal respiration, and microbial biomass among the different croplands were related to changes inmicrobial activity. Furthermore, the physical, chemical, and microbiological results indicated that the soils of Medicago sativa L. and Onobrychis sativa L. were of higher quality than the Vicia sativa L. soil

Pre- and Post-Windstorm leaf area index of Carpinus betulus trees in an urban forest patch

Natural disturbances are rather rare for the urban forests compared to the anthropogenic ones. However, forcible natural impact may be substantially destructive such as severe storms. Instantaneous defoliation is one of the significant signature of the storm severity. A multipurpose vegetation parameter, Leaf Area Index (LAI) is used as an indicator of instantaneous defoliation which may occur as a result of immediate leaf fall jointly with the stem and branch breakages or uprooting. Enhancing the idea, LAI of the Carpinus betulus trees were analyzed before and after the devastating storm in Balamba urban forest patch of Bartin Province at the northwestern of Turkey. The maximum speed of the severe storm was 117 km/h and enough to destruct the trees. Consequently LAI ceased 24\% as a result of instantaneous defoliation both in recreation and control sites indicating the severity of damage. Southwester which is associated with heavy rainfall and represent the winds with maximum speeds in the region led to this change. The inexistence of extraordinary meteorological data before and after the severe storm indicates that the wind speed was the main reason for such damage. The same percentage of LAI decrease within the recreation and control sites supports the situation that the soil compaction due to recreation has no definite influence on the severity of windthrow. Scattered pattern of annual maximum wind speeds particularly for the last fifteen years are possible to be the implications for climate change