Agricultural land abandonment is an emerging problem in European Union (EU), and about 11% of agricultural EU land is at high risk of abandonment in the coming 10 years. Land abandonment may have both positive and negative effects in ecosystems. Due to the potential for land abandonment to increase soil fertility, the study of vegetation succession effects on soil quality is of great importance. In this study, we investigated an abandoned vineyard where, after a period of 30 years, rows and alleys were characterized by two different forms of vegetation succession: natural recolonization by trees along the rows and by herbaceous vegetation in the alleys. No-tilled alleys covered by herbaceous vegetation of a neighboring conventionally cultivated vineyard were used as a comparison. Soil samples were chemically characterized (pH, extractable element, and available and total metals), and analyzed for the determination of carbon (C) and nitrogen (N) pools; hydrolytic and phenol oxidizing (PO) enzyme activities involved in C, N, and phosphorus (P) cycles; and the enzyme ratios. Results highlighted that natural recolonization by trees increased the organic C and N soil pools by 58% and 34%, respectively, compared to the natural recolonization by herbaceous vegetation. Moreover, natural recolonization by trees reduced β-glucosidase by 79%, urease by 100%, alkaline phosphastase by 98%, acid phosphatase specific hydrolytic activities by 50%, and catechol oxidase and laccase specific oxidative activities by 127% and 119%, respectively, compared to the renaturalization by herbaceous vegetation. In addition, the natural recolonization by trees reduced the C (βglu):C (PO) enzymes ratio by 16% compared to that of the conventional vineyard. Comparing the natural recolonization by herbaceous vegetation with that of the conventional vineyard revealed little significant difference (15% of the measured and calculated parameters); in particular, PO activities significantly decreased in the renaturalized vineyard with herbaceous vegetation by 49% (catechol oxidase) and 52% (laccase), and the C (βglu):C (PO) enzyme ratio showed a reduction (−11%) in the vineyard naturally recolonized by herbaceous vegetation compared to the conventional vineyard. This highlights that the type of vegetation succession that takes place after land abandonment may have a significant impact in terms of soil fertility and C accrual potential. These results help to focus attention on the practices used in agro-forestry that should be adopted in abandoned agro-ecosystems to increase their biodiversity, soil C stock, and soil quality, because these indicators are affected by the type of vegetative coverage.

中文翻译：

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土壤对农业土地放弃的反应：意大利北部葡萄园的案例研究

农业用地废弃是欧盟（EU）新出现的问题，未来 10 年，欧盟约 11% 的农业用地面临废弃的高风险。土地遗弃可能对生态系统产生积极和消极的影响。由于弃地可能会增加土壤肥力，因此研究植被演替对土壤质量的影响非常重要。在这项研究中，我们调查了一个废弃的葡萄园，在 30 年后，行和小巷的特征是两种不同形式的植被演替：沿行的树木和小巷中的草本植被的自然重新定植。以邻近传统栽培葡萄园的草本植被覆盖的免耕小巷作为比较。对土壤样品进行化学表征（pH、可提取元素、和可用金属和总金属），并分析用于测定碳 (C) 和氮 (N) 池；参与 C、N 和磷 (P) 循环的水解和酚氧化 (PO) 酶活性；和酶的比例。结果突出显示，与草本植被的自然再定植相比，树木的自然再定植使有机 C 和 N 土壤池分别增加了 58% 和 34%。此外，树木的自然重新定植使 β-葡萄糖苷酶降低了 79%，脲酶降低了 100%，碱性磷酸酶降低了 98%，酸性磷酸酶特异性水解活性降低了 50%，儿茶酚氧化酶和漆酶特异性氧化活性分别降低了 127% 和 119% ，与草本植被的再自然化相比。此外，树木的自然重新定植降低了 C (βglu)：与传统葡萄园相比，C (PO) 酶的比例提高了 16%。将草本植被的自然重新定植与传统葡萄园的自然重新定植进行比较，发现几乎没有显着差异（测量和计算参数的 15%）；特别是，在具有草本植被的再自然化葡萄园中，PO 活性显着降低了 49%（儿茶酚氧化酶）和 52%（漆酶），并且 C（βglu）：C（PO）酶比在与传统葡萄园相比，葡萄园自然地被草本植被重新定植。这突出表明，土地废弃后发生的植被演替类型可能对土壤肥力和碳积累潜力产生重大影响。