Effects of vegetation restoration on soil quality in fragile karst ecosystems of southwest China

Abstract

<jats:p>Soil quality assessment is important for karst ecosystems where soil erosion is significant. A large amount of vegetation restoration has been implemented since the early 21st century in degraded karst areas across southwestern China. However, the impacts on soil quality of different restoration types rarely have been compared systematically. In the current study, we investigated the soil quality after a number of vegetation restoration projects as well as their adjacent cropland by analyzing soil samples. Six vegetation restoration types were evaluated, including one natural restoration (natural shrubland, protected for 13 years), three economic forests (4 years <jats:italic>Eucalyptus robusta</jats:italic>, 4 years <jats:italic>Prunus salicina</jats:italic> and 6 years <jats:italic>Zenia insignis</jats:italic>) and two mixed forests (1 year <jats:italic>Juglans regia</jats:italic>–crop and 13 years <jats:italic>Toona sinensis</jats:italic>-<jats:italic>Pennisetum purpureum</jats:italic> ). We evaluated the benefits of different restoration types more accurately by setting each adjacent cropland as the control and setting the variation between the corresponding restored and control site as the evaluation object so that the background differences of six sites could be eliminated. The results indicated that natural shrubland, <jats:italic>Toona sinensis</jats:italic>-<jats:italic>Pennisetum purpureum</jats:italic> and <jats:italic>Zenia insignis</jats:italic> were effective in improving soil quality index (SQI) in degraded karst cropland largely due to their higher SOC and TN content. The variation of SQI (VSQI) of natural shrubland was significantly higher than that in <jats:italic>Eucalyptus robusta</jats:italic>, <jats:italic>Prunus salicina</jats:italic> and <jats:italic>Juglans regia</jats:italic>-crop in total soil layer (0–30 cm) (<jats:italic>P</jats:italic> &lt; 0.05), indicating natural shrubland had better capacity to improve soil quality. The boosting regression tree model revealed that vegetation restoration type explained 73.49% and restoration time explained 10.30% of the variation in VSQI, which confirmed that vegetation restoration type and restoration time are critical for achieving soil reserves. Therefore, it is vital to select appropriate vegetation type in restoration projects and recovery for a long time in order to achieve better soil quality. The current study provides a theoretical basis on which to assess the effects of different vegetation restoration types on the heterogeneous degraded karst areas.</jats:p>

Spatial patterns and influencing factors of soil SOC、DOC、ROC at initial stage of vegetation restoration in a karst area

“…Some studies reported a significant positive correlation between soil ROC, DOC, and SOC contents in brick red soil environments (Huang et al, 2015;Guan and Fan, 2020). However, we observed a higher ROC content in the karst area than the non-karst area with extremely significant effects of geomorphology and spatial location on soil ROC.…”

“…At present, some achievements made and widespread attentions on vegetation restoration in karst areas, however, researches were mostly focused on the corresponding restoration models and land use patterns. For example, previous reports examined the differences between natural and artificial restorations (Hu et al, 2018;Hu et al, 2020), the relationships between vegetation restoration measures and soil quality via model calculations (Zhang et al, 2019b), and the effects of different vegetation types on soil nutrients (Guan and Fan, 2020). Nevertheless, the mechanisms of vegetation restoration on soil property variability and the synergistic carbon cycle in karst areas have yet to be revealed (Rubino et al, 2010;Wu et al, 2022b).…”

Identification and predictability of soil quality indicators from conventional soil and vegetation classifications

“…All soil quality factors varied significantly (P < 0.01) by AVCs except soluble N and reduced N factors though none discriminated more than four groups. Similarly, Peng et al [19] and Guan and Fan [60] found strong evidence that different vegetation restoration types accounts for significant variations in the soil quality in different areas. It is possible that some of the soil quality factors that were insensitive to vegetation may represent inherent soil qualities that are controlled by other key factors of soil formation (e.g.…”

Study of Soil Nitrogen in Karst Rocky Desertification Areas: a Literature Review

“…In fact, due to the differences in temperature, altitude, land use and vegetation types, soil nitrogen distribution may be different [44]. showed that some vegetative restoration patterns have more significant effects on the total nitrogen and available nitrogen contents of the soils than other patterns [48][49][50][51]. 2021) studied the relationships between land use patterns and land quality in the Karst rocky desertification areas of Guizhou and Guangxi, and they found that land use patterns can cause changes in total soil nitrogen, available nitrogen and alkaline hydrolysable nitrogen contents; in terms of changes, woodland is the highest, and farmland is the lowest [52][53][54][55].…”