Climate change has resulted in major changes in plant phenology across the globe that includes leaf‐out date and flowering time. The ability of species to respond to climate change, in part, depends on their response to climate as a phenological cue in general. Species that are not phenologically responsive may suffer in the face of continued climate change. Comparative studies of phenology have found phylogeny to be a reliable predictor of mean leaf‐out date and flowering time at both the local and global scales. This is less true for flowering time response (i.e., the correlation between phenological timing and climate factors), while no study to date has explored whether the response of leaf‐out date to climate factors exhibits phylogenetic signal. We used a 52‐year observational phenological dataset for 52 woody species from the Forest Botanical Garden of Heilongjiang Province, China, to test phylogenetic signal in leaf‐out date and flowering time, as well as, the response of these two phenological traits to both temperature and winter precipitation. Leaf‐out date and flowering time were significantly responsive to temperature for most species, advancing, on average, 3.11 and 2.87 day/°C, respectively. Both leaf‐out and flowering, and their responses to temperature exhibited significant phylogenetic signals. The response of leaf‐out date to precipitation exhibited no phylogenetic signal, while flowering time response to precipitation did. Native species tended to have a weaker flowering response to temperature than non‐native species. Earlier leaf‐out species tended to have a greater response to winter precipitation. This study is the first to assess phylogenetic signal of leaf‐out response to climate change, which suggests, that climate change has the potential to shape the plant communities, not only through flowering sensitivity, but also through leaf‐out sensitivity.
18 February 2021 in European Journal of Forest Research
Soil extracellular enzymes play a key role in mediating the degradation of soil organic matter, but little is understood as to how the pattern of soil extracellular enzymes could be altered by nitrogen (N) addition. In this study, the effects of N addition (started from 2006, four treatments: control, 0 g N·m–2·yr–1; low N addition, 2.5 g N·m–2·yr–1; high N addition, 5.0 g N·m–2·yr–1) on soil extracellular enzymes and microbial biomass in a natural secondary forest of Northeastern China. The results showed that the activity of urease, sucrase, peroxidase and N-acetyl-β-D-glucosidase decreased with N addition, and the activity of acid phosphatase and leucine aminopeptidase increased significantly with N addition. Soil total N, temperature at 5 cm soil depth, pH value, microbial biomass carbon and microbial biomass N were the key factors affecting soil enzyme activity. In summary, the enzyme activity related to soil organic matter degradation shows a decreasing trend under N addition. The results suggest that the increase in N deposition will slow down the degradation of soil organic matter in natural secondary forest, which is more conducive to the accumulation of organic matter in the soil.