Optimizing canopy‐forming algae conservation and restoration with a new herbivorous fish deterrent device

The role of herbivorous fish in threatening marine forests of temperate seas has been generally overlooked. Only recently, the scientific community has highlighted that high fish herbivory can lead to regime shifts from canopy‐forming algae to less complex turf communities. Here, we present an innovative herbivorous fish deterrent device (DeFish), which can be used for conservation and restoration of marine forests. Compared to most traditional fish exclusion systems, such as cages, the DeFish system does not need regular cleaning and maintenance, making it more cost‐efficient. Resistance of DeFish was tested by installing prototypes at different depths in the French Riviera and in Montenegro: more than 60% of the devices endured several years without maintenance, even if most of them were slightly damaged in the exposed site in Montenegro. The efficacy of DeFish in limiting fish herbivory was tested by an exclusion experiment on Cystoseira amentacea in the French Riviera. In a few months, the number of fish bite marks on the seaweed was decreased, causing a consequent increase in algal length. The device here presented has been conceived for Mediterranean canopy‐forming algae, but the same concept can be applied to other species vulnerable to fish herbivory, such as kelps or seagrasses. In particular, the DeFish design could be improved using more robust and biodegradable materials. Innovative engineering systems, such as DeFish, are expected to become useful tools in the conservation and restoration of marine forests, to complement other practices including active reforestation, herbivore regulation, and regular monitoring of their status.     

Shrub influences on seedling performance when restoring the slow‐growing conifer Pilgerodendron uviferum in southern bog forests

Forest restoration is most efficient if it can take advantage of facilitative interactions between established vegetation and planted trees. However, positive and negative interactions have been identified in a number of plant communities. After centuries of anthropogenic fires, forest recovery has been extremely slow in southern bog forests previously dominated by the slow‐growing and vulnerable conifer Pilgerodendron uviferum on Chiloé Island, Chile. Today, the landscape is dominated by secondary shrublands with scattered patches of Sphagnum moss and limited natural tree regeneration. We hypothesized that the retention of secondary shrubs facilitates the early performance of P. uviferum restoration plantings by providing better microsite conditions. To test this hypothesis, we compared the response of seedlings planted on sites prepared at two levels of intervention: after shrubs had been removed or where shrubs were retained. Shrub retention showed a nurse‐plant effect on P. uviferum seedlings 4 years after planting, which resulted in reduced physiological stress (measured as Fv/Fm) for seedlings, as well as reduced browsing. Consequently, the seedlings growing in areas with shrub retention had larger height increment and higher vitality than those in areas where shrubs had been removed. Thus, the more open micro‐site conditions created by shrub removal resulted in generally poorer seedling performance, although seedling mortality—which was low overall (approximately 2–4%)—showed no significant difference between the two levels of intervention. These findings have direct implications for the restoration of slow‐growing conifers that can tolerate extreme wet conditions in highly degraded forests.     

Seed storage: maintaining seed viability and vigor for restoration use

Effective seed storage after sourcing (harvesting or purchasing) is critical to restoration practitioners and native seed producers, as it is key to maintaining seed viability. Inadequate seed storage can lead to a waste of both natural and economic resources when seeds of poor quality are sown. When working with native species with unknown storage behavior, general assumptions can be made based on studies on related species, and standard practices may be applied with caution; however, an investigation should be conducted to understand if specific storage requirements are needed and for how long seeds can be stored before they lose significant viability. In this paper of the Special Issue Standards for Native Seeds in Ecological Restoration, we provide an overview of the key concepts in seed storage and the steps to take for effective storage of native seeds for restoration use.     

Shoreline infrastructure degradation and increasing littoral naturalization accommodates juvenile fish and crab assemblages in heavily urbanized Upper New York Harbor

Many estuarine shorelines are influenced by urbanization. Extensive shoreline modification in Upper New York Harbor (UNYH) included port development, landfilling marshes, and armoring. Recent sedimentation in constructed shipping terminal embayments, abandonment of shoreline structure maintenance, subsequent recruitment of upland and intertidal vegetation, and restoration projects have naturalized some shorelines in this urban setting. We determined the species composition and relative abundance of fishes and crabs in shallow shoreline habitats in constructed embayments of UNYH with seine sampling to determine the potential for restoring similar isolated shallow water sites as functional habitats. Twenty‐seven identified species of fishes and crabs, including seasonally transient and resident marsh species, were represented in samples dominated by Menidia menidia, but marsh resident and coastal ocean species were also periodically abundant. Differences in assemblage structure among the sampled embayments as measured by principal components analysis were weak despite some differences in the slope and colonization of vegetation along shorelines. The mere presence of shallow shorelines was sufficient to recruit numerous species. Assemblage differences relative to a nearby relatively unaltered estuary revealed a lack of southern, warm affiliated species reflecting a natural clinal gradient. Marsh resident species dominated in UNYH, but not as strongly as at the reference estuary. Together with a previously published evaluation of life cycle connectivity for several sentinel species, this study shows that even small, isolated projects seeking to restore shallow shorelines add value to the estuarine landscape and are worth pursuing.     

Biological soil crust salvage for dryland restoration: an opportunity for natural resource restoration

Biocrusts' functional importance and vulnerability to disturbance have motivated consistent interest in biocrust restoration, as well as a recent increase in research to cultivate biocrusts in laboratory and greenhouse settings for use in ecological restoration. As part of a sustainable approach to developing biocrust restoration, we argue that a complementary step is to improve and accelerate methods for salvaging biocrusts that would otherwise be destroyed in a forthcoming disturbance. The increasing rate and scale of disturbance pressures in drylands where biocrusts flourish means that the supply of salvageable biocrust and demand for that material in restoration greatly exceed the present cultivable supply. In this article we describe the state of knowledge for biocrust salvage, present a simple set of steps for conducting a salvage harvest, discuss risks and benefits when considering using salvage, and suggest future research directions to facilitate scaling up biocrust restoration using salvaged material. A focus on the use of salvaged biocrust as a restoration source may prove an important step to improve ecological restoration in notoriously difficult to restore dryland ecosystems.     

长春花(Catharanthus roseus)对热带珊瑚岛生理生态适应性研究

长春花(Catharanthus roseus)是夹竹桃科的一种亚灌木植物,具有重要的药用价值和观赏价值,在前期的试验性种植中,发现长春花对热带珊瑚岛环境有很强的适应性。为了探讨长春花对热带珊瑚岛环境的生理生态适应性,该文以移植到热带珊瑚岛的长春花和生长于海南省文昌市苗圃的长春花为研究对象,对其叶片的形态解剖结构、生理学特征、营养元素含量等进行了分析。结果表明:(1)与苗圃生长的长春花和其他耐胁迫的植物相比,移植到热带珊瑚岛上的长春花具有叶片厚、栅栏组织发达、比叶面积小等形态解剖特征,这些特征有利于其光能吸收、水分储存和对环境资源的利用。(2)长春花的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较高,表现出较强的抗氧化性和抗胁迫能力。(3)长春花的叶绿素a和叶绿素b含量较低,可以减少过多的光能进入叶绿体光合系统,防止过剩的光能对光合系统产生伤害。(4)热带珊瑚岛土壤养分含量低,但生长在岛上的长春花叶片的营养元素含量高,表现出很强的养分吸收和利用能力。因此,长春花对干旱、贫瘠等恶劣生境具有很好的适应能力,可以作为热带珊瑚岛植被恢复工具种。     

炼锌废渣-修复植物-凋落物体系的生态化学计量学研究

为揭示金属冶炼废渣堆场生态修复多年后,废渣-植物-凋落物系统中养分循环和系统维持机制。该研究以实现生态修复6 a的黔西北铅锌冶炼废渣堆场上土荆芥(Dysphania ambrosioides)、芦竹(Arundo donax)、刺槐(Robinia pseudoacacia)、构树(Broussonetia papyrifera)和柳杉(Cryptomeria fortunei)五种优势修复植物为对象,分析它们的主要营养器官(细根、粗根、茎/干、枝、叶片)、地表凋落物、植被下方表层废渣(0～10 cm)中碳(C)、氮(N)、磷(P)含量及化学计量特征,探讨它们之间的相互关系。结果表明:不同植物、不同营养器官间C、N、P的含量具有显著差异(P<0.05),C平均含量在两种草本植物中为茎>叶片>根>凋落物,在三种乔木中为干>枝>细根>粗根>叶片>凋落物; N和P的分布在草本植物中分别为叶片>凋落物>根>茎和叶片>根>凋落物>茎,在三种乔木中均为叶片>细根>凋落物>粗根>枝>干。五种植物中,柳杉各营养器官及凋落物中C含量均高于其他植物,N、P含量呈相反的规律; 刺槐中N含量最高。C:N和C:P在五种植物营养器官与凋落物中的变化规律跟N、P的分布相反,说明C:N和C:P分别主要受N和P含量影响。相关性分析指出,草本植物的N:P受N和P共同影响,三种乔木的N:P主要由N的分布决定,同时受到枝和叶片中P含量影响。五种植物中,仅豆科类刺槐的叶片N:P大于16,在系统中生长受P限制,其他植物生长均受N限制,说明刺槐更能适应贫瘠的废渣环境,建议在修复贫瘠的废渣堆场时优先选择豆科类植物作为先锋植物,改善基质养分条件。植被下方表层废渣中C、N、P含量基本都低于植物各营养器官及凋落物,不同修复植物下方对应的表层废渣中C、N、P含量间具有显著差异(P<0.05),草本植物修复下的废渣中C、N、P含量低于乔木修复下的含量。废渣-植物-凋落物体系中N、P、N:P之间的相关性分析显示,植物细根和凋落物中N、P含量与废渣中N、P含量及化学计量比关系更密切。     

上海城市近自然森林的重建动态

近自然森林作为城市植被恢复的重要模式,已在我国多地开展了实践,并衍生了新的造林模式。为评估不同近自然森林建设模式的群落恢复进程,本研究以上海城市裸地上重建的近自然森林为对象,通过长期监测两处分别应用原"宫胁法"与新"异龄复层落叶—常绿混交林"种植模式的近自然森林重建过程,从物种组成、垂直结构、生活型组成和目标恢复物种4个方面解析恢复动态。结果表明:两种造林模式恢复的近自然森林,随恢复进程其物种组成逐渐趋同,在十多年内已形成了落叶—常绿垂直混交结构;"异龄复层落叶—常绿混交林"造林模式可更好地促进常绿阔叶树种的恢复,尤其是常绿建群种红楠与小叶青冈。本研究证实了近自然森林恢复技术可以缩短亚热森林群落向演替后期发展的时间,以及新造林模式的有效性,为近自然森林技术的应用与实施提供了科学依据。     

干旱河谷微生境变化对乡土植物幼苗定植的影响

干旱区植被斑块状分布格局引起的微生境差异对植被更新影响显著。气候变化和人类活动扰动下, 干旱区生态系统微生境多样化, 急需揭示乡土植物定植对不同微生境斑块变化的响应及其种间差异性, 并采用微生境调控技术促进退化生态系统植被恢复。该研究选择岷江干旱河谷区自然分布的灌木、半灌木和裸地微生境斑块, 采用移栽鞍叶羊蹄甲(Bauhinia brachycarpa)幼苗的试验方法, 揭示微生境变化对幼苗定植的影响; 进一步以极端退化的道路边坡为案例, 通过6种乡土植物种子直播试验探讨微生境调控技术及其对乡土植物幼苗定植的促进作用。结果显示, 在自然生态系统中, 裸地斑块上幼苗保存率和生物量显著大于植被斑块, 表明裸地微生境有利于幼苗定植; 养分添加仅对裸地斑块中幼苗生物量积累有促进作用。在裸地斑块中, 叶片生物量所占的比例和比叶面积较小, 相反根和茎生物量所占的比例较大。道路边坡上植被恢复试验结果显示, 6种乡土植物均能较好地适应土石混杂的边坡生境, 多数物种出苗率大于60%; 灌木幼苗保存率大于75%, 并且形成镶嵌式乡土灌草群落结构。地表覆盖和养分添加提高了边坡上种子出苗率和幼苗保存率, 促进了幼苗定植和结构稳定。该研究提供了有效促进工程边坡上乡土植物定植的方法, 可为干旱、半干旱生态系统退化荒坡和工程破坏地乡土植被恢复提供理论依据和技术指导。