RESUMO
We integrated the meteorological records from 36 national weather stations and CN05.1 gridded daily observation dataset to analyze the climate change characteristics of Changbai Mountain eco-functional area. Linear tendency estimation, Mann-Kendall mutation test, cumulative anomaly method and Morlet wavelet analysis were used to investigate the temporal and spatial variation of temperature (annual temperature, seasonal temperature, extreme temperature), moisture (annual precipitation, seasonal precipitation, relative humidity), radiation (sunshine duration, sunshine percentage) and wind speed from 1961 to 2016. The results showed that, during 1961-2016, the temperature of this area increased, the radiation and wind speed decreased, and the precipitation varied periodically. Specifically, winter temperature [0.45 â·(10 a)-1] and the lowest temperature [0.74 â·(10 a)-1] significantly increased. The mean annual wind speed significantly decreased [-0.21 m·s-1·(10 a)-1]. No abrupt climate change was observed. The annual precipitation days decreased considerably [-7.01 d·(10 a)-1], which was different from the climate change pattern of Northeast China. The annual precipitation trend coefficient of this area was 16.06 mm·(10 a)-1 , which could not be simply depicted by increase or decrease in trend. The precipitation change in this area was dominated by periodically patterns, and the period was 26 years and 3 years. Our results would be instructive to the regional ecological assessment, and the research on ecosystem responses to climate change and phenological changes.
Assuntos
Mudança Climática , Ecossistema , China , Ecologia , TemperaturaRESUMO
The broad-leaved Korean pine forest is an important primary forest in Northeast China. Soil aggregates play important role in carbon fixation of forest ecosystem. Temporal-spatial substitution method was used in this study. We selected five forests with different succession stages: birch young forest, birch middle forest, birch mature forest, mature broad-leaved Korean pine fore-st, and over-mature broadleaved Korean pine forest. The distribution of soil aggregate particle size and agglomeration in organic carbon under different forests were investigated by wet sieving method. The results showed that soil aggregate size distributions and the proportions of soil aggregates were significantly different among succession stages. The mean mass diameter of aggregates was generally showed a unimodal trend along with the succession stages, peaking at birch mature forest stage. The organic carbon content in the aggregate of different particle-sizes in the soil increased firstly and then decreased slightly from early to late succession, and the maximum content of organic carbon in the aggregate was in broad-leaved Korean pine mature forest stage. Under the same succession stage, the content of organic carbon in the aggregate of different particle-sizes increased with the decreases of the particle size in the soil depth of 0 to 5 cm and 5 to 10 cm (except over-mature broad-leaved Korean pine forest at the end of succession), but it was the opposite in the soil depth of 10 to 20 cm. From the birch young forest at the early stage of succession to the over-mature broad-leaved Korean pine forest at the end of succession, organic carbon content in the aggregate of same particle-size had obvious vertical distribution characteristics, which significantly decreased with the increases of soil depth.
