Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, 610299 Chengdu, China; College of Ecology and Environment, Chengdu University of Technology, 610059 Chengdu, China.
Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany.
Sci Total Environ. 2024 Oct 20;948:174783. doi: 10.1016/j.scitotenv.2024.174783. Epub 2024 Jul 14.
Vegetation restoration in metallic tailing reservoirs is imperative to restore the post-mining degraded ecosystems. Extracellular enzymes determine microbial resource acquisition in soils, yet the mechanisms controlling the enzyme activity and stoichiometry during vegetation restoration in metallic tailing reservoirs remain elusive. Here, we investigated the variations and drivers of C-, N- and P-acquiring enzymes together with microbial community along a 50-year vegetation restoration chronosequence in the China's largest vanadium titano-magnetite tailing reservoir. We found a parabolic pattern in the enzyme activity and efficiency along the chronosequence, peaking at the middle restoration stage (∼30 years) with approximately six-fold increase relative to the initial 1-year site. The enzyme ratios of C:P and N:P decreased by 33 % and 68 % along the chronosequence, respectively, indicating a higher microbial demand of C and N at the early stage and a higher demand of P at the later stage. Soil nutrients directly determined the enzyme activities and stoichiometry, whereas microbial biomass and community structure regulated the temporal pattern of the enzyme efficiency. Surprisingly, increased heavy metal pollution imposed a positive effect on the enzyme efficiency indirectly by altering microbial community structure. This was evidenced by the increased microbial diversity and the conversion of copiotrophic to oligotrophic and stress-tolerant taxa along the chronosequence. Our findings provide new insights into microbial functioning in soil nutrient dynamics during vegetation restoration under increasing heavy metal pollution.
在金属尾矿库中进行植被恢复对于恢复矿业废弃后退化的生态系统至关重要。胞外酶决定了土壤中微生物的资源获取，但在金属尾矿库植被恢复过程中控制酶活性和化学计量的机制仍不清楚。在这里，我们调查了 C、N 和 P 获得酶以及微生物群落沿中国最大的钒钛磁铁矿尾矿库 50 年植被恢复时间序列的变化及其驱动因素。我们发现，随着时间的推移，酶活性和效率呈现出抛物线模式，在中恢复阶段（约 30 年）达到峰值，与初始 1 年的站点相比，增加了约 6 倍。沿时间序列，酶的 C:P 和 N:P 比值分别下降了 33%和 68%，这表明在早期阶段微生物对 C 和 N 的需求更高，而在后期阶段对 P 的需求更高。土壤养分直接决定了酶的活性和化学计量，而微生物生物量和群落结构则调节了酶效率的时间模式。令人惊讶的是，重金属污染的增加通过改变微生物群落结构，间接地对酶效率产生了积极影响。这一点可以从随着时间序列的推移，微生物多样性的增加以及从富营养型向寡营养型和耐受压力型的转变中得到证明。我们的研究结果为在重金属污染不断增加的情况下，植被恢复过程中土壤养分动态中微生物功能提供了新的见解。
