School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3122, Australia.
School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3122, Australia.
J Environ Manage. 2018 Dec 1;227:365-374. doi: 10.1016/j.jenvman.2018.09.004. Epub 2018 Sep 8.
Large trees are often seen as a means of offsetting negative consequences of growing urban densification. To increase the tree canopy cover of dense urban landscapes, developers, planners and urban tree managers are often forced to plant into damaged and compacted sites. Compacted urban soils can hinder the establishment and growth of deep rooted, woody plants by: 1) impeding root exploration and development which is critical for water and nutrient acquisition; 2) reducing infiltration of water into the soil and the availability of water to plants; and 3) reducing gas exchange and the balance between anaerobic and aerobic conditions. At three sites in Melbourne, Australia with compacted and damaged soils, we established four soil remediation treatments: 1 & 2) tillage to 0.25 m with and without 50% (v/v) municipal green waste compost (MGWC) additions, and 3 & 4) tillage to 0.5 m with and without 50% MGWC addition, plus a non-remediated control. Each treatment was replicated (n = 3), and one Corymbia maculata (spotted gum) tree was planted into the centre of each 2 × 2 m treatment plot (n = 15), at all three sites (n = 45). Bulk density and field-saturated hydraulic conductivity were improved by tillage, at least in the short-term. The use of MGWC may maintain these changes for longer. Depending on site soil conditions tree growth may be improved by tillage alone. At one site, we found that additions of MGWC lead to nitrogen immobilisation due to site soil conditions. At another site, deep tillage (with or without MGWC) led to significantly improved tree growth. Compacted and degraded urban soils may be improved through simple tillage and/or organic amendment strategies for the successful establishment of deep rooted woody plants. However, site soil conditions will dictate whether the addition of MGWC is beneficial or not, as one site showed no positive response to any tillage or MGWC. This research has examined a technique that can be used by landscape managers to improve soil physical characteristics and, in certain circumstances, can improve deep-rooted woody plant establishment and growth in challenging compacted urban soil conditions.
大树通常被视为抵消城市密集化带来的负面影响的一种手段。为了增加密集城市景观的树冠覆盖率，开发商、规划师和城市树木管理者经常被迫在受损和压实的场地种植树木。压实的城市土壤会通过以下方式阻碍深根木本植物的建立和生长：1）阻碍对水和养分获取至关重要的根系探索和发育；2）减少水渗透到土壤中以及植物可用水的数量；3）减少气体交换以及厌氧和有氧条件之间的平衡。在澳大利亚墨尔本的三个场地，土壤压实且受损，我们设立了四个土壤修复处理：1 和 2）耕作至 0.25 米，分别添加和不添加 50%（体积/体积）城市绿色废物堆肥（MGWC），以及 3 和 4）耕作至 0.5 米，分别添加和不添加 50%MGWC，外加一个未修复的对照。每个处理都进行了重复（n=3），在每个 2×2 m 处理区的中心种植了一棵 Corymbia maculata（斑皮桉）树（n=15），在三个场地（n=45）都进行了种植。耕作至少在短期内改善了土壤的容重和田间饱和导水率。MGWC 的使用可能会使这些变化维持更长时间。根据场地土壤条件，单独耕作可能会提高树木的生长。在一个场地，我们发现由于场地土壤条件，MGWC 的添加导致氮素固定。在另一个场地，深耕作（无论是否添加 MGWC）导致树木生长显著改善。压实和退化的城市土壤可以通过简单的耕作和/或有机改良策略得到改善，以便成功建立深根木本植物。然而，场地土壤条件将决定添加 MGWC 是否有益，因为一个场地对任何耕作或 MGWC 都没有积极响应。本研究检验了一种技术，景观管理者可以使用该技术来改善土壤物理特性，并且在某些情况下，可以改善深根木本植物在具有挑战性的压实城市土壤条件下的建立和生长。
