关键词: 落叶松人工林, 碳组分, 氮组分, 微生物生物量, 间伐

Abstract: To understand the adaptive strategies of growth and survival ofCaragana korshinskii seedlings to sand burial and water availability in desert, an experiment was conducted in a desert shrubland in Lingwu Baijitan National Nature Reserve of Ningxia. The results showed that water addition facilitated the survival and growth of C. korshinskii seedlings. The final retention rate (FRR), shoot height (SH), leaf area per plant (LAPP) and total dry mass (TDM) of seedlings all significantly increased under water addition (P<0.05). Moreover, lateral root number (LRN), leaflet blade number (LBN), relative growth rate (RGR) and net assimilation rate (NAR) all increased to some extent. The survival and growth of C. korshinskii seedlings were inhibited by sand burial. The FRRs of seedlings with water addition were significantly higher than that without water addition by the end of the experiment (P<0.05). Basal stem diameter, LBN, LAPP, TDM, RGR of sand buried seedlings significantly decreased (P<0.05), but it was not the case for SH. The taproot length, LRN and NAR of seedlings declined in various degrees. The specific leaf area (SLA), specific root length (SRL) and specific shoot length (SSL) of sand buried seedlings were significantly higher than those without sand burial (P<0.05), while root shoot ratio (RSR) of the former was substantially lower than the latter (P<0.05). The SRL of sand buried seedlings significantly declined under water addition (P<0.05). No significant difference in RSR, SLA and SSL of seedlings, however, were detected between treatments of water addition and no water addition regardless of sand burial.

Key words: larch plantation, microbial biomass., carbon fraction, thinning, nitrogen fraction