Carbon and nitrogen storage and distribution of four forest ecosystems in Liupan Mountains, northwestern China

Abstract

Carbon (C) and nitrogen (N) are important elements of forest ecosystems, and quantifying C and N storage and distribution is a critical step for better understanding of C and N cycles in forest ecosystems. C and N pools in forests vary greatly, depending on the forest type, forest growth stage, and site quality. The mechanisms controlling the spatial and temporal variation of C and N accumulation in forest ecosystems, especially in the northwestern China, have been sporadically investigated in the past. In this paper, the content, storage and distribution of C and N were investigated in four http: / / www.ecologica.cn typical forests at the Liupan Mountains in Ningxia, northwestern China. The four forest types included Larix principis鄄 rupprechtii plantation, Pinus armandii secondary forest, Betula platyphylla secondary forest, and Prunus salicina shrubs. The concentrations of C and N were measured in different organs of the trees, and the contents of C and N in the vegetation layers of trees, shrubs, grasses, and layers of humus, and soil (0-100 cm depth) were estimated. Storage, composition, and distribution of C and N in these ecosystems were examined. The results showed that the concentrations of C did not significantly differ among the different organs and tree species, but the concentration of N varied. The highest N concentration was found in the leaves and the lowest in the trunk. The contents of C and N were higher in the above鄄ground biomass than in the below鄄ground biomass for both shrubs and grasses. The C contents decreased in the order of tree layer > shrub layer > grass layer, but N contents increased in the order of tree layer < shrub layer < grass layer in the studied forests. The C content was lower in the humus layer than in each of the vegetation layers, but the situation was opposite for the N content. The contents of both C and N decreased with increasing soil depth. The total C storage in the four forest ecosystems was in the following order: B. platyphylla secondary forest (640. 02 t / hm 2) > P. armandii secondary forest (450.98 t / hm 2) > L. principis鄄rupprechtii plantation (364.56 t / hm 2) > P. salicina shrub (196.55 t / hm 2). The total N storage decreased from 47.02 t / hm 2 in B. platyphylla secondary forest to 36.19 t / hm 2 in P. armandii secondary forest, 27.86 t / hm 2 in L. principis鄄rupprechtii plantation and 15.99 t / hm 2 in P. salicina shrub ecosystems in the study sites. The amount of C and N in the soil (0-100 cm depth) accounted for the major proportion of the total C and N storage in the studied forest ecosystems, with the range of 84.7%-93.9% for C and 98.1%-98.6% for N for the four forest types. On average, the C / N ratio in the soil and in the entire ecosystem was 12.48 and 13.52 in B. platyphylla secondary forest, 11.84 and 13.12 in L. principis鄄rupprechtii plantation, 11.70 and 12.29 in P. salicina shrub, and 10.76 and 12.56 in P. armandii secondary forest, respectively. In addition, the C / N ratio decreased gradually from the tree layer to shrub layer, grass la...

Research on Teaching Reform Integrating Information Technology Innovation -- A Case Study of Logistics Information Technology and Management Course

“…For example, in the logistics information and management part of the course content reconstruction, "logistics black technology" is introduced for the understanding of logistics information technology and logistics information standardization, from "Beacon fire reporting military intelligence to flying pigeon book delivery to post station delivery to the Internet". The standardization of logistics information introduces the historical story of "the same track, the same text and the same wheel" in the Qin Dynasty; Collect the entrepreneurial story of Wang Yue, the father of two-dimensional code, and the R&D case of Huawei's chip in information technology; In the logistics information system part of the introduction of Kyushu Tong war epidemic story; In the tracking technology, the importance of the United States GPS in the Gulf War and China's Beidou were introduced [11]. Through the integration of ideology and politics in the curriculum, students can understand the development and application of technology to truly realize the effect of learning, as shown in Table 3 below.…”