南水北调中线水源区弃耕地草本植被演替初步研究

以南水北调中线水源区不同年限的退耕弃荒地为研究对象,分析了其草本植被恢复阶段的群落学特征,用聚类分析和极点排序的方法对各群落类型进行了划分,探讨了其自然演替规律,并对弃耕地植被恢复的一般机理进行了初步探讨。结果表明,草本植被恢复演替过程可明显分为以下几个阶段：荠菜(Capsella bursa—pastoris) 铁苋菜(Acalypha australis) 小白酒草(Conyza canadensis)群落(退耕1年);小白酒草(Conyza canadensis) 灰绿藜(Chenopodium glaucum)群落(退耕2年);艾蒿(Artemisia argyi) 小白酒草(Conyza canadensis) 猪毛蒿(Artemisia scoparia)群落(退耕3～6年);白茅(Imperata cylindrica) 牛尾蒿(Arternisia subdigitata) 野艾蒿(Artemisia lavandulaefolia) 狗尾草(Setaria viridis)群落(退耕7～12年^ )。退耕3年时群落已经趋于稳定,草本植被基本上得到恢复。     

Mixed responses of farmland birds to the Conservation Reserve Enhancement Program in Pennsylvania

The Pennsylvania Conservation Reserve Enhancement Program (CREP) was initiated in 2000 and within 4 years, 40,000 ha of conservation grasslands were established in southern Pennsylvania. We determined whether CREP habitat has benefitted farmland and grassland bird populations during the 10 years since the program began. From 2001 to 2010, bird surveyors conducted road-side point counts in a 20-county area in south-central Pennsylvania. We observed positive CREP effects on the abundances (in 2009–2010) and changes in abundance (from 2001–2002 to 2009–2010) of 5 species, including eastern meadowlark (Sturnella magna); negative CREP effects for 3 species, including vesper sparrow (Pooecetes gramineus); and no CREP effects for 2 species, including grasshopper sparrows (Ammodramus savannarum). We additionally observed changes in the size and direction of the local CREP effects (within 250 m of count locations) depending on the amount of CREP grassland or field cover in the surrounding landscape (within 5,000 m of survey routes). For example, the local CREP effect on the change in abundance of eastern meadowlarks was 15 times greater at points nested within landscapes with 9% CREP cover compared to landscapes with 1% CREP cover, indicating the potential for greater benefits of adding new CREP grasslands to areas with more CREP habitat already in the surrounding area. We conclude that more careful spatial targeting of CREP enrollment could improve the benefits of the program for farmland and grassland bird populations. © The Wildlife Society, 2013     

Development of a nature value index for pastoral farmland—A rapid farm-level assessment

Sustainable agriculture is important for the safeguarding of natural resources (e.g. semi-natural habitats, clean water and energy), food production and for the survival of rural communities. As part of the EU strategy towards sustainability Member States are committed to identifying and protecting areas of agrobiodiversity. Identification of the extent and support of High Nature Value (HNV) farmland across the EU was an important policy requirement of Member States Rural Development Programmes (RDP) (2007–2013) but problems defining the extent of HNV farmland have delayed progress to date. Following a five step statistical process, we developed a simple 10 point nature value index based on percentage improved agricultural grassland, stocking density (LU/ha Utilisable Agricultural Area) and length of linear habitats per hectare on a farm. We propose an index that can be used to highlight farms with low biodiversity allowing targeting of sustainability measures such as increasing field boundary area or reducing inorganic Nitrogen inputs, farms that are already sustainable from a biodiversity perspective, and could be labelled as such through national programs or even farms that are High Nature Value (HNV) and should be targeted through results-based agri-environment schemes. This nature value index has potential to be applied to a range of farmed pastoral landscapes in North West Europe's Atlantic biogeographic region. The methodology used in the development of the index has the potential to be used in other biogeographic zones to develop similar indices of nature value at farm level. This index is a simple to use, easily accessible identification tool based on farm-level data which can be utilised in sustainability indices and HNV farmland identification.     

Do agri-environmental schemes contribute to high nature value farmland? A case study in Emilia-Romagna (Italy)

The objective of the paper is to determine whether the agri-environmental schemes included in the rural development programme of Emilia-Romagna (Italy) have played a role in enhancing the nature value of farmland in that region. An indicator is developed for biodiversity friendly farming practices (BFFP) and its level and distribution at the municipality level is measured, using data derived from the two last national agricultural censuses, year 2000 and 2010. Thereafter, the relationship between BFFP and participation in rural development measures is analysed by way of spatial econometric techniques. The main result of the paper are consistent with the expectation that RDPs have an impact on how BFFP changes. However, measures supporting organic farming contribute to the evolution of its distribution in a positive manner, whilst the other measures investigated, such as integrated production, do not. The paper also highlights the fact that these effects have significant spatial correlations.     

干旱区城郊种植业水足迹分析与适宜耕地规模测算——以乌鲁木齐市为例

水足迹方法能够完整、清晰地描述种植业的耗水特征。以干旱区绿洲城市乌鲁木齐市为例,运用水足迹模型分析种植业产品耗水特征,构建水足迹强度系数以探讨种植业耗水对本地水资源的影响度,进而从作物水足迹和水源类型角度建立绿洲耕地规模测度模型测算乌鲁木齐市适宜耕地规模,研究发现:①作物生长期水足迹受土壤水分胁迫和产量损减影响呈现差异化;②2005-2011年间,绿水强度系数波动剧烈,蓝水强度系数均值超出容量极限,作物生长期对蓝水资源依赖性较强,从而进一步加剧了蓝水资源的匮乏;③乌鲁木齐市合理耕地规模约为6万hm²,2005-2011年种植业实际耕地规模均处于超载状态,超载量变化呈现先降后升的特征,现状种植业发展模式对绿洲生态系统扰动不断加剧。     

农田栽参土壤改良中肥料对土壤元素及酶活性的影响

为探究农田栽参土壤改良中肥料对土壤元素与土壤酶活性的影响, 于2019年5月21日采集经混合肥、土地乐、腐殖酸、木醋液、益生源处理过的土壤样品, 对其土壤养分与土壤酶活性进行研究。结果表明: 不同肥料在土壤中发挥出不同的作用, 施用混合肥的土壤SOM、ACa含量最高分别为139.51 g·kg-1、848.9 mg·kg-1。施用土地乐生物有机肥后土壤中AP和AMn含量最高分别为36.7 mg·kg-1、126.12 mg·kg-1。施用腐殖酸后土壤中AFe、电导率、AK数值最高分别为737.36 mg·kg-1、59.67 mg·kg-1、794.87 mg·kg-1。施用木醋液与益生源菌剂后各养分均有不同程度增加; 过氧化氢酶活性在混合肥处理后最低, 对照处理最高。漆酶活性在腐殖酸处理后最低, 木醋液处理最高。蔗糖酶活性在腐殖酸处理最低, 混合肥处理最高。脲酶活性在腐殖酸处理最低, 益生源处理后最高; 相关性分析表明, 土壤养分与土壤酶活性有密切关系, 存在不同程度的相关性。五种肥料在土壤改良中都有显著效果     

Biodiversity and the mitigation of climate change through bioenergy: impacts of increased maize cultivation on farmland wildlife

The public promotion of renewable energies is expected to increase the number of biogas plants and stimulate energy crops cultivation (e.g. maize) in Germany. In order to assess the indirect effects of the resulting land‐use changes on biodiversity, we developed six land‐use scenarios and simulated the responses of six farmland wildlife species with the spatially explicit agent‐based model system ALMaSS. The scenarios differed in composition and spatial configuration of arable crops. We implemented scenarios where maize for energy production replaced 15% and 30% of the area covered by other cash crops. Biogas maize farms were either randomly distributed or located within small or large aggregation clusters. The animal species investigated were skylark (Alauda arvensis), grey partridge (Perdix perdix), European brown hare (Lepus europaeus), field vole (Microtus agrestis), a linyphiid spider (Erigone atra) and a carabid beetle (Bembidion lampros). The changes in crop composition had a negative effect on the population sizes of skylark, partridge and hare and a positive effect on the population sizes of spider and beetle and no effect on the population size of vole. An aggregated cultivation of maize amplified these effects for skylark. Species responses to changes in the crop composition were consistent across three differently structured landscapes. Our work suggests that with the compliance to some recommendations, negative effects of biogas‐related land‐use change on the populations of the six representative farmland species can largely be avoided.     

National and regional patterns of habitat association with foraging Barn Swallows Hirundo rustica in the UK

Capsule Barn Swallows showed a consistent association with cattle across the UK, but certain landscape features, particularly mixed field types and tall trees, were also important.

Aim To provide nationally representative data on habitat selection in foraging Barn Swallows.

Method Observers carried out four timed point counts within an allocated 2-km square(s). Point counts were at least 500 m apart and considered as independent sample points. Each point count covered 100 m radius and was visited twice during the summer. An index of foraging activity was derived from the number of foraging passes made by Barn Swallows within ten minutes. The maximum count of Swallows present was also recorded. Habitat data included the presence or absence of landscape features and buildings and the proportion of area covered by particular crop and boundary types within the 100 m count radius.

Results Cattle were the single most important and most consistent variable associated with foraging Barn Swallows, in every UK region. Horses were also important in the southeast. Grassland was only important if livestock were present. Foraging pass rates were higher where count circles contained a mixture of grass and arable fields rather than just one or the other. There was a general positive relationship between foraging pass rates and the presence of tall trees in boundaries, and this was significant in the arable eastern region of the UK, where their relative importance of concentrating prey may be more acute.

Conclusion Historical changes in the distribution and availability of habitat features associated with foraging Barn Swallows are consistent with regional differences in population change for this species in the UK. These patterns of association are discussed in terms of changes in land use, the widespread loss of mixed farming and simplifications to landscape complexity.     

华北平原农田CO2浓度变化特征

旨在了解农田CO2浓度长期动态变化特征、趋势、浓度增量分布模式等,收集了2007—2018年中国气象局固城生态与农业气象试验站开路式涡相关CO2浓度观测数据。研究了华北平原农田CO2浓度的年际、年内、昼夜和CO2通量等动态变化特征,对比分析了华北平原农田CO2浓度与城市站和大气本底站CO2浓度变化趋势及差异。结果表明,近十多年来华北平原农田CO2年平均浓度显著升高31.0 μmol/mol（r=0.263, P<0.01）,年均增幅(2.58 μmol/mol)与全球和瓦里关本底站大气CO2浓度增幅接近,但农田CO2浓度年际和年内季节变化波动巨大,日平均浓度和逐时平均浓度标准差分别为33.7和33.5 μmol/mol。夜间CO2平均浓度395.8 μmol/mol,比白天高36.2 μmol/mol（10.1%）,8月最高差值达到74.4 μmol/mol（20.6%）。在作物生长季节,5月和8—9月白天CO2浓度出现的两个谷值准确地对应了CO2通量动态变化的两个峰值,表明4—9月昼间CO2浓度和通量动态变化很好地反映了华北平原冬小麦和夏玉米生长过程、农事活动和农田碳交换的关系。农田CO2浓度动态变化与城市、湿地和大气本底站的变化特征不同,表明其动态变化的形成机制有差异。农田CO2浓度昼夜及季节变化特征为研究和评估CO2浓度升高影响作物生长和产量提供指导依据。     

雄安新区上游白洋淀流域水质净化提升目标下的生态恢复格局优化

白洋淀流域是雄安新区重要的淡水来源之一,流域内退耕政策在改善水质同时大幅降低了农田面积。如何通过退耕空间规则的优化权衡水质净化效率与农田面积是亟待解决的问题。通过设置基于不同退耕规则的情景,并与实际情景对比,提出了退耕规则的优化方案。结果表明：相同面积下,河岸带退耕的水质净化效率高于坡耕地退耕;相同退耕规则下,退耕还林驱动的水质净化效率高于还灌,还草;单位面积河岸带退耕的水质净化效率随缓冲区距离增加而降低;300m河岸带退耕还林情景下的水质净化率提升高于其他所有模拟情景,也比实际退耕情景（2015）高,同时农田面积降幅也低于实际情景。研究表明通过对退耕规则进行空间优化不仅能够满足区域水质净化提升的目标,还有利于保障区域农田面积,减少生态系统服务间的权衡。