Decoupled recovery of ecological communities after reclamation

Abstract

Grassland restoration is largely focused on creating plant communities that match reference conditions. However, these communities reflect only a subset of the biodiversity of grassland systems. We conducted a multi-trophic study to assess ecosystem recovery following energy development for oil and gas extraction in northern US Great Plains rangelands. We compared soil factors, plant species composition and cover, and nematode trophic structuring between reclaimed oil and gas well sites (“reclaims”) that comprise a chronosequence of two—33 years since reclamation and adjacent, undeveloped rangeland at distances of 50 m and 150 m from reclaim edges. Soils and plant communities in reclaims did not match those on undeveloped rangeland even after 33 years. Reclaimed soils had higher salt concentrations and pH than undeveloped soils. Reclaims had lower overall plant cover, a greater proportion of exotic and ruderal plant cover and lower native plant species richness than undeveloped rangeland. However, nematode communities appear to have recovered following reclamation. Although total and omni-carnivorous nematode abundances differed between reclaimed well sites and undeveloped rangeland, community composition and structure did not. These findings suggest that current reclamation practices recover the functional composition of nematode communities, but not soil conditions or plant communities. Our results show that plant communities have failed to recover through reclamation: high soil salinity may create a persistent impediment to native plant growth and ecosystem recovery.

Managing invasive plants on Great Plains grasslands: A discussion of current challenges

“…This can lead to habitat conditions favoring invasives over native plants, especially later-successional natives. For example, energy development and restoration of impacted sites in the Bakken oilfield region of western North Dakota have resulted in soils with reduced soil organic matter (SOM), depauperate microbial communities ( Viall et al 2014 ), and elevated salinity ( Sylvain et al 2019 ). These disturbed soil conditions then lead to greater amounts of bare ground and plant communities dominated by ruderal weeds and invasive grasses ( Simmers and Galatowitsch 2010 ;Sylvain et al 2019 ).…”

Ecological remediation zoning of territory based on the ecological security pattern recognition: Taking Jiawang district of Xuzhou city as an example

“…1 期 倪庆琳 等：基于生态安全格局识别的国土空间生态修复分区 件并依靠生态系统演替促进生态群落恢复，例如重点生态功能区保护与修复工程 [18] 、草地 退化生态修复工程 [19] 等在中国、美国、加拿大、巴西、匈牙利、南非等国家均取得一定 成效，以及由此产生的产业延伸 [20] 、乡村重构 [21] 、生态影响或响应 [22] 、生态修复策略 [23][24][25] 等，有从农牧民满意度 [19] 、关键影响因素评估 [26] 、生态恢复干预清单 [27] 、生态群落恢复 [28] 等探讨生态修复实施；众多研究多集中于单一修复目标，将生态安全格局与生态修复分 区结合的研究则较少。 徐州市贾汪区曾是两淮国家大型煤炭基地与华东地区煤炭工业基地的重要组成部 分，2011 年被国家确定为资源枯竭型城市，2016 年 11 月关闭最后一座矿井；在历史时期 为江苏省和华东地区整体经济发展尤其是能源生产做出了历史性贡献，却遗留下了地表 沉降、土壤损失、水源涵养等生态环境问题 [29] 。历经近十年生态环境治理，坚持"生态 优先，绿色发展"战略，践行"绿水青山就是金山银山" ，积极探索资源型城市转型发展 与系统性生态修复，明确各类区域治理导向和重点，现已成为生态修复重要路径。 本文以资源型城市国土空间生态修复的空间不均衡性为切入点，基于连通性-敏感 性-生态重要性框架 [4] [8] 、对生态安全有重要意义或具有辐射功能的 生境斑块，是构建生态安全格局的基础，其至少要实现三个层次的目标：具有较好生态 景观连通性、较高生态因子敏感性和重要生态系统服务 [4] (表 1) 。 根据蒙吉军等 [30] 的研究成果，生态景观连通性选择将整体连通性 (dIIC) 、可能连通性 (dPC) 细分为内部、通量和连接体后进行空间叠加，更细致地表征斑块间的连通性 [18] ，以 考虑潜在的动物迁移和植物传播生态修复条件 [17] 。结合自然生态属性、自然-社会生态 复合属性和社会生态属性三个方面，生态因子敏感性主要归纳为地质地貌 (如坡度、高 程、采矿范围) 、水系防护 (湖泊、河流水系) 、覆被类型 (土地利用类型、植被覆盖 度) 和保护区 (风景名胜区以及自然保护区) 等，以反映资源型城市区域内部属性特征 和潜在风险类型 [31] 。根据 《生态功能区划技术暂行规程》《江苏省主体功能规划》《江苏 省重要生态功能保护区区域规划》《徐州市重要生态功能保护区规划》 ，主要生态系统服 务分为水源涵养、固碳释氧以及多样性保护 [7] [9] ，生态阻力赋值主要根据专家知识或经验数据进行。参考 陆禹等 [6] 、李保杰等 [32] 的研究，按照单位面积土地利用类型生态系统服务价值赋予相应的 阻力值：耕地 75、林地 28、草地 75、水域 1、未利用地 80、建设用地 100，构建基本生 态阻力面。 由于煤炭资源长期高强度开采，微地貌产生形变，地面塌陷积水，形成局部内循环 生态系统，一定程度上割裂生态源地、切断廊道，影响了生物之间的交流 [33] ，造成井田边 界内外生态阻力因采煤活动的显著差异。贾汪区原井田边界内大部分采空区的沉降活跃 期已过 (以 2016 年最后关闭的旗山煤矿 93118 工作面为例，平均采深约为 550 m，地表移 动延续时间为 3.6 年) ，越靠近中心地带与外部联系越被隔绝；塌陷损毁严重地段仍为积 水洼地或改造为鱼塘或整治为湿地公园；或为季节性积水耕地或挖深垫浅为鱼塘或与周 边土地利用类型无异。本文以煤矿井田边界为基础，查阅历史岩移观测资料或文献 [34] ，估…”