下一次绿色革命:基于植物群落设计重塑城市生境丰度

气候变化、大规模物种灭绝、快速城市化以及工业土地利用极大影响了人们的生活品质,并削弱了地球上所有生命所依赖的核心生态系统服务功能。保护城市外围的自然土地已不足以确保人类自身的生存。为减少负面的环境影响,修复必不可少的生态系统服务,重塑人与自然元素的联系,并创造更健康、更具韧性的城市景观,有必要在城市和工业景观中采用具有超高生态功能并能引起公众强烈共鸣的种植方式,从根本上转变城市景观规划设计方法。介绍了美国Phyto景观设计工作室应用的基于植物群落的种植设计方法,解释创新的种植系统如何重建城市多样而丰裕的生境。阐述了植物之间、植物与人、植物与更大的环境如何联系的3个核心原则,通过案例说明该种植模式的应用,并讨论使其适应中国城市独特环境和社会政治背景的策略。

A buried Neolithic paddy soil reveals loss of microbial functional diversity after modern rice cultivation

It has been documented that human activities are causing the rapid loss of taxonomic, phylogenetic, genetic and functional diversity in soils. However, it remains unclear how modern intensive rice cultivation impacts the soil microbiome and its functionality. Here we examined the microbial composition and function differences between a buried Neolithic paddy soil and an adjacent, currently-cultivated paddy soil using high throughput metagenomics technologies. Our results showed that the currently cultivated soil contained about 10-fold more microbial biomass than the buried one. Analyses based on both 16S rRNA genes and functional gene array showed that the currently cultivated soil had significantly higher phylogenetic diversity, but less functional diversity than the buried Neolithic one. The community structures were significantly different between modern and ancient soils, with functional structure shifting towards accelerated organic carbon （C） degradation and nitrogen （N） transfor- mation in the modem soils. This study implies that, modern intensive rice cultivation has substantially altered soil microbial functional structure, leading to functional homogenization and the promotion of soil ecological functions related to the acceleration of nutrient cycling which is necessary for high crop yields.

Variation in the methods leads to variation in the interpretation of biodiversity-ecosystem multifunctionality relationships

Aims Biodiversity is often positively related to the capacity of an ecosystem to provide multiple functions simultaneously(i.e.multifunctionality).However,there is some controversy over whether biodiversity–multifunctionality relationships depend on the number of functions considered.Particularly,investigators have documented contrasting findings that the effects of biodiversity on ecosystem multifunctionality do not change or increase with the number of ecosystem functions.Here,we provide some clarity on this issue by examining the statistical underpinnings of different multifunctionality metrics.Methods We used simulations and data from a variety of empirical studies conducted across spatial scales(from local to global)and biomes(temperate and alpine grasslands,forests and drylands).We revisited three methods to quantify multifunctionality including the averaging approach,summing approach and threshold-based approach.Important Findings Biodiversity–multifunctionality relationships either did not change or increased as more functions were considered.These results were best explained by the statistical underpinnings of the averaging and summing multifunctionality metrics.Specifically,by averaging the individual ecosystem functions,the biodiversity–multifunctionality relationships equal the population mean of biodiversity-single function relationships,and thus will not change with the number of functions.Likewise,by summing the individual ecosystem functions,the strength of biodiversity–multifunctionality relationships increases as the number of functions increased.We proposed a scaling standardization method by converting the averaging or summing metrics into a scaling metric,which would make comparisons among different biodiversity studies.In addition,we showed that the range-relevant standardization can be applied to the threshold-based approach by solving for the mathematical artefact of the approach(i.e.the effects of biodiversity may artificially increase with the number of functions considered).Our study highlights different approaches yield different results and that it is essential to develop an understanding of the statistical underpinnings of different approaches.The standardization methods provide a prospective way of comparing biodiversity–multifunctionality relationships across studies.

Contrasting responses of native and alien plant species to soil properties shed new light on the invasion of dune systems

Aims Among terrestrial ecosystems,coastal sandy dunes are particularly prone to alien plant invasion.Many studies related the invasion of dune habitats to anthropic causes,but less is known about the role of soil properties and plant traits in plant invasion.In this study,we tested the relationships between soil features and alien plant invasion in dune systems,focusing on the interplay between soil nutrients,soil salinity and plant functional traits.Methods Study sites were sandy barrier islands of the Marano and Grado lagoon(northern Adriatic Sea).One hundred plots(4 m×4 m)were selected within 10 areas according to the main habitats occurring along the ecological gradient of dune system(foredune,backdune and saltmarsh).In each plot,we recorded all plant species occurrence and abundance and we collected a soil core.For each soil sample,soil texture,conductivity(as proxy of soil salinity),organic carbon and nitrogen content were analyzed and related to the species number and cover of native and alien plants.Variation of main reproductive and vegetative functional traits among habitats was also analyzed for both alien and native species.Important Findings Soil properties were strongly related to overall plant diversity,by differently affecting alien and native species pools.In backdune,the most invaded habitat,a high soil conductivity limited the number of alien species,whereas the content of soil organic carbon increased along with alien plant abundance,suggesting also the occurrence of potential feedback processes between plant invasion and soil.We found a significant convergence between native and alien plant functional trait spectra only in backdune habitat,where environmental conditions ameliorate and plant competition increases.Our findings suggest that in harsh conditions only native specialized plants can thrive while at intermediate conditions,soil properties gradient acts in synergy with plant traits to curb/facilitate alien plant richness.

Resource enrichment combined with biomass removal maintains plant diversity and community stability in a long-term grazed grassland

Aims Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen(N)and water limitation.In contrast,the absence of biomass removal can cause species loss by elevating light competition and weakening community stability,which is exacerbated by N and water enrichment.Hence,how to maintain species diversity and community stability is still a huge challenge for sustainable management of worldwide grasslands.Methods We conducted a 4-year manipulated experiment in six long-term grazing blocks to explore combination of resource additions and biomass removal(increased water,N and light availability)on species richness and community stability in semiarid grasslands of Inner Mongolia,China.Important Findings In all blocks treated with the combination of resource additions and biomass removal,primary productivity increased and species richness and community stability were maintained over 4 years of experiment.At both species and plant functional group(PFG)levels,the aboveground biomass of treated plants remained temporally stable in treatments with the combination of N and/or water addition and biomass removal.The maintenance of species richness was primarily caused by the biomass removal,which could increase the amount of light exposure for grasses under resource enrichment.Both species asynchrony and stability of PFGs contributed to the high temporal stability observed in these communities.Our results indicate that management practices of combined resource enrichment with biomass removal,such as grazing or mowing,could not only enhance primary productivity but also maintain plant species diversity,species asynchrony and community stability.Furthermore,as overgrazing-induced degradation and resource enrichment-induced biodiversity loss continue to be major problems worldwide,our findings have important implications for adaptive management in semiarid grasslands and beyond.