The timings of the onset and ending of xylogenesis define the time window when environmental conditions are suitable for xylem formation. The relationship between the occurrence of xylem phenological events and the related climatic factors is critical to revealing how xylem formation responds to the changing climate. Given that temperature is the most important factor influencing growth in the boreal forest, we monitored air temperature and xylem phenology at five permanent plots of black spruce (Picea mariana (Mill.) BSP) along a latitudinal gradient of the boreal forest of Quebec, Canada. Microcores were collected weekly or biweekly from five to ten trees per site during the growing seasons from 2002 to 2019. We compared the relationships between air temperature and timings of the onset and termination of xylogenesis, testing the hypothesis that spring temperatures trigger the initiation of cambial activity. The onset of xylogenesis occurred from late May (DOY 149) to mid-June (DOY 163), and it terminated between late August (DOY 240) and late September (DOY 270). The spring phases of xylem phenology showed similar inter-annual variation among sites, while the variation in autumnal phases was less correlated among sites. The onset of xylogenesis was negatively correlated with the mean May temperature, and the correlations were consistent among sites, with r ranging from −0.61 to −0.77. The warmer May temperatures would advance cambial resumption, allowing the initial hypothesis that spring temperatures are a driving factor of xylogenesis to be accepted. With an increase of 1 °C in the mean May temperature, cambial resumption could be advanced by 2.7 days. Yet, no relationship between the termination of xylem phenology and monthly temperature was established, suggesting that other factors, possibly endogenous, could have affected the xylem phenology in autumn. Under warming conditions, we expect an advancement in the onset of xylogenesis, which may lengthen the growing season and potentially enhance cell production in black spruce.

En tr This phytosociological investigation is conducted in various disturbed forests around Murree hills. The main purpose of study is to explore community types, associated ground flora and their relation to soil characteristics. Eight community types and two monospecific tree stands have been recognized as follows: Pinus wallichiana (pure), Pinus roxburghii (pure), Pinus wallichiana-Quercus baloot, Pinus wallichiana-Cedrus deodara, Pinus wallichiana-Abies pindrow, Pinus wallichiana-Quercus dilatata, Quercus dilatata-Cedrus deodara, Pinus roxburghii-Pinus wallichiana, Pinus roxburghii-Cedrus deodara, Pinus roxburghii-Quercus dilatata. Pinus wallichiana dominates monospecifically in 8 stands while Pinus roxburghii -Pinus wallichiana community types found at 5 locations. Pinus wallichiana formed community type with Cedrus deodara and Abies pindrow at 4 locations separately. Highest stand density achieved in Pinus wallichiana-Cedrus deodara and Pinus roxburghii-Quercus dilatata community i.e. 128 trees/h. Highest basal area (48.06 (m²/ha) recorded from Pinus wallichiana (pure) stands. Pinus wallichiana-Pinus roxburghii communities correlated significantly (p < 0.05) with tree density. Range of DO. pH, Temperature, Conductivity, Salinity, ORP and chemical parameters in each community type has also shown and discussed. Bu fitososyolojik araştırma, Murree tepeleri çevresindeki çeşitli bozulmuş ormanlarda yapılmıştır. Çalışmanın temel amacı topluluk türlerini, ilişkili zemin florasını ve toprak özellikleri ile ilişkilerini araştırmaktır. Sekiz bitki topluluğu ve iki monospesifik meşcere tanımlanmıştır: Pinus wallichiana (saf), Pinus roxburghii (saf), Pinus wallichiana-Quercus baloot, Pinus wallichiana-Cedrus deodara, Pinus wallichiana-Abies pindrow, Pinus wallichiana-Quercus dilatata, Quercus dilatat-Cedrus deodara, Pinus roxburghii-Pinus wallichiana, Pinus roxburghii-Cedrus deodara, Pinus roxburghii-Quercus dilatata. Pinus wallichiana 8 standda monospesifik olarak baskınken, 5 yerde bulunan Pinus roxburghii-Pinus wallichiana topluluk türleri. Pinus wallichiana, Cedrus deodara ve Abies ile 4 yerde ayrı ayrı topluluk oluşturmuştur. Pinus wallichiana-Cedrus deodara ve Pinus roxburghii-Quercus dilatata topluluğunda, yani 128 ağaç/saatte elde edilen en yüksek meşcere yoğunluğu olarak gözlenmiştir. Pinus wallichiana (saf) meşcerelerinden kaydedilen en yüksek bazal alan (48.06 (m²/ha) olarak kaydedilmiştir. Pusus wallichiana-Pinus roxburghii toplulukları ağaç yoğunluğu ile anlamlı bir şekilde korelasyon göstermiştir (p <0.05). DO. PH, Sıcaklık, İletkenlik, Tuzluluk, ORP her topluluk türündeki kimyasal parametreler de gösterilmiş ve tartışılmıştır.