Abstract

The turnover rate and the main mechanisms of accumulation of biophilous elements (C, N, P, K) in the litters of native, forest, and pasture ecosystems of the Northern Caspian region (Volgograd oblast, Dzhanybek Experimental Station of the Institute of Forest Science, Russian Academy of Sciences) were assessed from the data of a four-year-long field experiment on the decomposition of dominant plants of steppe and desert phytocenoses, falloff of introduced oak (Quercus robur L.), and sheep feces from rangeland. It was shown that the litter of native steppe associations accumulates 16–19 times more carbon and nitrogen and 2–2.5 times more potassium and phosphorus as compared with the litter of pastures. The accumulation of C, N, P, and K in the litter of native desert plant communities is 1.5 times more intensive than in the litter of pasture communities. The reserves of C, N, P, and K in the litter of oak plantation exceeds 5–8 times that in the steppe litter. The rates of C and N cycling calculated as the ratio of stock to input mass is 6–7 times slower in the litter of oak plantation than in the litter of steppe community. This corresponds to a lower decomposition constant of oak leaves as compared with decomposition constants of dominant plants of steppe communities. The rate of litter decomposition in phytocenoses with sparse vegetation (steppe pasture and desert native and pasture communities) is an order of magnitude higher than in the native steppe associations, which is related to increased physicochemical decomposition of plant residues under sunlight. Specific features of litter formation should be taken into account when assessing the stability of anthropogenic ecosystems in the region.

中文翻译：

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北里海半荒漠原生生态系统和人为生态系统凋落物中的亲生物元素循环

摘要

北里海地区（伏尔加格勒州，森林科学研究所Dzhanybek实验站）原生，森林和牧场生态系统凋落物中周游速率和主要生物累积机理（C，N，P，K） ，俄罗斯科学院）从在草原和荒漠phytocenoses的主要植物分解了四年之久的现场实验的数据进行评估，衰减区推出橡木（的夏栎大号。），以及来自牧场的绵羊粪便。结果表明，与牧场的凋落物相比，原生草原协会的凋落物碳和氮的累积量高16-19倍，钾和磷的累积量高2-2.5倍。天然荒漠植物群落凋落物中碳，氮，磷和钾的积累密度是牧场群落凋落物中的1.5倍。橡树凋落物中C，N，P和K的储量超过草原凋落物的5–8倍。碳和氮循环速率是由橡木种植园垫料中的草木与输入质量之比计算得出的，比草原社区垫料慢6-7倍。与草原群落优势植物的分解常数相比，这对应于橡树叶的分解常数较低。具有稀疏植被的植物群落中的凋落物分解速率（草原牧场以及荒漠和牧草群落）比原生草原协会高一个数量级，这与日光下植物残留物的物理化学分解增加有关。在评估该地区人为生态系统的稳定性时，应考虑到凋落物形成的特定特征。