Vegetation Re‐development After Fen Meadow Restoration by Topsoil Removal and Hay Transfer

We investigated the effects of different restoration treatments on the development of fen meadow communities: (1) depth of topsoil removal, with shallow (circa 20 cm) and deep (circa 40 cm) soil removal applied, (2) transfer of seed‐containing hay, and (3) access of large animals. We carried out a full factorial experiment with all combinations of these factors and monitored it for 4 years. We studied the effect of seed availability in the soil seed bank on species abundance in the vegetation and compared it to the effect of species introduction by hay. We observed large differences in species composition between different treatments after 4 years. The combination of hay transfer, deep soil removal, and exclusion of large animals resulted in a community with highest similarity to the target vegetation. We found that the transfer of seeds with hay had a larger effect on species abundance than the soil seed bank. Hay transfer appeared to have important consequences on vegetation development because it speeded up the establishment of the target vegetation.     

Moss Regeneration for Fen Restoration: Field and Greenhouse Experiments

Fen bryophytes are an important component of natural fens and should be included in fen restoration projects. The goal of this study was to examine the regeneration capabilities of nine bryophytes common to moderate-rich and poor fens in North America. A greenhouse experiment was carried out to examine the limitations and optima for the regeneration of fen bryophytes under different light and water regimes. A field experiment tested these same bryophytes in the presence of three potential nurse-plants. In the greenhouse experiment, the presence of shade increased regeneration success for eight out of nine species. A high water level was ideal for the regeneration of the majority of species tested. In the field experiment, Sphagnum species had the highest regeneration, and all species had higher regeneration under a dense canopy of herbaceous plants. Fen bryophytes show good potential for use in restoration projects because the tested bryophytes regenerated well from fragments.     

Restoration of brook valley meadows in the Netherlands

Until recently, restoration measures in Dutch brook valley meadows consisted of re-introducing traditional management techniques, such as mowing without fertilisation and low-intensity grazing. In the Netherlands, additional measures, such as rewetting and sod cutting, are now carried out on a large scale to combat negative influences of drainage and acidifying influences by atmospheric deposition. An analysis of successful and unsuccessful projects shows that restoration of brook valley meadows is most successful if traditional management techniques are applied in recently abandoned fields that had not been drained or fertilised. Large-scale topsoil removal in former agricultural fields that had been used intensively for several decades is often unsuccessful since seed banks are depleted, while hydrological conditions and seed dispersal mechanisms are sub-optimal. In areas with an organic topsoil, long-term drainage had often led to irreversible changes in chemical and physical properties of the soil. Successful sites were all characterised by a regular discharge of calcareous groundwater provided by local or regional hydrological systems, and, where not very long ago, populations of target species existed. On mineral soils, in particular, sod removal in established nature reserves was a successful measure to increase the number of endangered fen meadow species. It is argued that attempts to restore species-rich meadows should be avoided on former agricultural fields, where pedological processes have led to almost irreversible changes in the soil profile and where soil seed banks have been completely depleted. From a soil conservation point of view, such areas should be exploited as eutrophic wetlands that are regularly flooded.     

Quick Target Vegetation Recovery after Restorative Shrub Removal and Mowing in a Calcareous Fen

Removal of shrubs and trees is an important management and restoration practice to promote openness and light‐dependent vegetation in fens, especially as tree cover is increasing in previously open wetlands. The effects of woody vegetation removal on target species have been poorly documented in wetlands up to now. In this study, I investigated the effect of tree and shrub removal (especially of Juniperus communis) on the target vegetation in a partly overgrown and degraded grazed rich fen after 6 years. I also tested whether additional intensified management by mowing could promote initial recovery. Shrub removal resulted in a rapid recovery of species‐rich fen vegetation such that after 6 years brown moss cover more than tripled and target species richness doubled and became similar to values of a reference area in a favorable conservation status. Additional mowing resulted in a much higher abundance of the target rich fen vascular plants. The reasons for the success at this site may be the proximity to well‐developed rich fen vegetation, presence of cattle that dispersed diaspores, and presence of bare, colonizable substrate. Thus, it may be more beneficial to restore and expand already existing sites in a partly favorable status than to restore severely deteriorated sites. Extensive management by woody vegetation removal may be an alternative method to maintain high conservation values of open mires and other wetlands, where grazing or mowing is not necessary or feasible to meet future needs in response to overgrowth caused by global warming.     

大明山中山植被恢复过程植物物种多样性的变化

对大明山中山退化生态系统植被恢复过程植物物种多样性的发展研究表明：大明山中山植被恢复过程物种数量的增减总是伴随着阳性先锋物种的衰退和中生性顶极种的发展。恢复过程中植物物种数量呈前期（２～２０年）迅速增加,中期（５０～６０年）减少,后期（１５０年以上）维持一定水平的发展趋势。中山区退化生态系统的植被恢复是朝着地带性植被类型的方向发展的,此过程可以不经过马尾松先锋林阶段,而直接进入以阔叶树种为优势的先锋群落。因此,大大缩短了中山山地退化生态系统植被向中生性顶极植被恢复的进程。     

Germination Requirement of Vallisneria natans Seeds: Implications for Restoration in Chinese Lakes

Due to eutrophication submerged macrophytes have disappeared from many Chinese lakes. This is unfortunate as submerged macrophytes are important to improve water quality, and its re-establishment is therefore desirable. For this purpose a potential method to use is re-seeding, this being particularly attractive due to the high seed productivity of V. natans. We conducted laboratory studies to investigate the effects of five environmental variables (temperature, substratum, oxygen, light availability, and burial depth) on the seed germination of V. natans. Our results showed that a wide temperature range (25–35 °C) was favorable for germination; that seeds germinated well under both gravel and silt; that anaerobic condition proved to accelerate seed germination although the final germination percentage did not rise; and that light and burial acted as limiting factors. These results suggest that V. natans is a potential candidate for successful restoration of vegetation in lakes recovering from eutrophication.     

Testing Germination of Species for Hydroseeding Degraded Mediterranean Areas

The germination performance of native species and their suitability for a rapid erosion control are uncertain. Together with their relatively low commercial availability and high costs, these are still strong reasons preventing their common use in hydroseeding for restoration of Mediterranean degraded slopes, despite the increasing number of studies recommending it. In this study, 14 non‐native (commercial) and native herb and woody species were tested. Their germination performance was evaluated under laboratory (Petri dishes) and greenhouse conditions (seeds sown in target substrate). The results obtained were compared with the seedling densities in a Mediterranean quarry slope hydroseeded with the same species. In the laboratory, commercial species had a better germination performance than most native species, but this trend was not maintained in the greenhouse. Greenhouse tests were extended beyond spring and showed that many native species germinated better, or exclusively in autumn. Germination performance and success decreased, from laboratory to greenhouse and field conditions, for many species, but not for all. Relative to field performance, the predictive value of laboratory and greenhouse tests was poor, yet sowing on the target substrate under greenhouse conditions may be a better approach for certain native species. The main drawbacks revealed by native species in the present study included: (1) relatively slow germination; (2) seasonality; and (3) seed dormancy‐breaking requirements. The results suggest that these problems may be overcome through species selection, seed pre‐treatments, hydroseeding scheduling, and/or manipulation of seeding density and relative species proportion.     

Spontaneous Vegetation Succession in Gravel–Sand Pits: A Potential for Restoration

Vegetation variability, the participation of target and undesirable species, and the role of local species pool were studied in the course of spontaneous succession in disused gravel–sand pits. The study was conducted in various regions of the Czech Republic, Central Europe. The regions represented either agrarian lowlands with a relatively warm and dry climate or mostly woodland uplands with a relatively cold and wet climate. The gravel–sand pits (36) comprised stages of different age from 1 to 75 years since abandonment. Altogether, 224 vegetation samples were recorded with species cover (%) visually estimated. Species affinity to different vegetation types was assessed in each sample based on the species cover. Local site factors, such as water table and soil characteristics, and landscape characteristics, namely climatic parameters, presence of nearby (semi)natural plant communities and main land cover categories in the broader surroundings, were evaluated as well as the participation of target (grassland, woodland, and wetland) and undesirable (ruderal, alien) species. Ordination analyses showed that vegetation succession led to target grassland, wetland, or woodland vegetation depending on local site factors, especially moisture and the presence of (semi)natural vegetation in the surroundings (local species pool). Restoration of target vegetation in disused gravel–sand pits by processes of spontaneous succession can be possible and successful in about 25 years, especially if (semi)natural vegetation exists in the surroundings. The invasion of the alien tree Robinia pseudacacia must be taken into consideration within the dry sites in lowlands.     

五种藓类植物的孢子萌发与原丝体发育

本文对中华缩叶藓(Ptychomitrium sinense)、狭叶缩叶藓(P.linearifolium)、威氏缩叶藓(P.wilsonii)、葫芦藓(Funaria hygrometrica)和立碗藓(Physcomitrium sphaericum)5种国产藓类植物的孢子萌发和原丝体发育进行研究,结果表明不同藓类孢子萌发和原丝体发育类型不同,孢子萌发和原丝体发育方式与藓类植物的生态环境有关.     

The Effect of Restoration Methods on the Quality of the Restoration and Resistance to Invasion by Exotics

The methods employed in a restoration can impact the resulting plant community. This study investigated the effect of restoration method on several indices of plant community structure by comparing two restoration methods conducted over an 8‐year period to a naturally colonized postagricultural field and a remnant grassland. The restoration methods included (1) distributing seed over fallow fields and (2) planting established seedlings in combination with seeding a fallow field. We found greater plant community resemblance (i.e., floristic quality, native species richness, and native diversity) to remnant grasslands with the introduction of seedlings during the first 4 years of restoration. There was also a negative correlation between the native plant diversity and the density of exotic plants in the restoration. This relationship suggests that introducing native plants in postagricultural fields may represent an effective management strategy to reduce exotic plant density.     

Winter Burning and the Reduction of Cornus sericea in Sedge Meadows in Southern Wisconsin

To control shrubs, which are increasing in dominance in wetlands worldwide, winter burning may be an important tool, especially from the perspective of minimizing urban hazards. The goal of this project was to determine if winter burning was successful in reducing the dominance (mean percentage cover and maximum height) of Cornus sericea in sedge meadows in southern Wisconsin, where shrubs proliferated after cattle were excluded. Experimental burn and control plots were set up within sedge meadows, including an ungrazed “reference” site that had been little, if ever, grazed and a “historically grazed” site, a recovery site that had not been grazed by cattle since 1973. None of the dominant species including C. sericea was significantly affected by burning for either mean percentage cover or maximum height (analysis of variance: no burning × species interaction). Both mean percentage cover and maximum height were only weakly related to burning (28.1 and 14.3% of the variability contributed to the cumulative percentage of the coefficient of determination, respectively) at both sites based on non‐metric multidimensional scaling analysis. Although species richness increased in burned plots in 1999 and 2000, no differences were apparent between pre‐burned and unburned plots in 1997 and unburned plots in 1999 and 2000 (analysis of variance: year × burning interaction). After burning in the ungrazed site, herbaceous species appeared that had not been detected for decades, including Chelone glabra and Lathyrus palustris. Exotic species were present in both the ungrazed reference and recovery site. Although winter burning treatments did not reduce the dominance of woody shrub species in the site recovering from cattle grazing, burning was useful in stimulating the maintenance of species richness in the ungrazed sedge meadow.     

Landscape Pattern Dynamics and Mechanisms during Vegetation Restoration: A Multiscale,Hierarchical Patch Dynamics Approach

The spatial pattern of vegetation changes during ecological restoration, and these changes are affected by the process of restoration. The objective of this study was to integrate the pattern and mechanism of forest restoration in the Dinghushan Nature Reserve (DNR), Guangdong, China, based on data from remote sensing and long‐term field observations. We studied the pattern dynamics of three main forest types and their underlying mechanisms during restoration following a multiscale, hierarchical patch dynamics framework that integrates population, community, and landscape processes. Remote sensing data were used to determine the changes in landscape pattern during different periods of forest restoration from 1978 to 2006. At the landscape scale, the number, area, and perimeter of the needle/broad‐leaved mixed forest (MF) and the evergreen broad‐leaved forest (BF) increased, whereas those of the tropical needle‐leaved forest (NF) decreased during succession. Our analysis based on long‐term field observations indicated that the change rate of NF was lower than that of MF during 1981–1996, but became much higher during 1996–2007. The rate of change in landscape pattern and the progression of succession stages were consistent with each other. Our results also showed that species regeneration and community succession are the biological basis of forest landscape dynamics during vegetation restoration. Landscape pattern analysis allowed us to show “what” happened during vegetation restoration and “where,” and population and community analysis indicated “why” and “how” it happened.     

Restoration of fen ecosystems in the Vecht River plain: cost-benefit analysis of hydrological alternatives

In the Vecht river plain, the vegetation diversity has been diminished during recent decades, due to hydrological changes and resulting eutrophication. Different options are discussed for hydrological management aimed at abating the eutrophication and at stimulating the characteristic mesotraphent succession phases of the fen vegetation. The ecological impact of the management plans are estimated with the hydro-ecological model ICHORS; this model takes into account the relations between the non-biotic environment and the presence of hydrophytes and phreatophytes. The impact of the hydrological options is assessed, after rearrangement of the predicted values of the species to values of the required fen vegetation. These results are incorporated in the management options with the water balances of the polders. Information on the costs of the options is used as a basis for a cost-benefit analysis. Technical hydrological solutions such as purification of the supplied water might contribute to the eutrophication abatement, but they are on their own unlikely to restore the ecosystems. Contrastingly, options involving the restoration of the original hydrology would probably lead to the characteristic mesotraphent fen vegetation once more, and the financial implications of this are likely to be the more favourable in the long-term.     

Natural Establishment of Specialist Plant Species after Topsoil Removal and Soil Perturbation in Degraded Calcareous Sandy Grassland

Specialist plant species in calcareous sandy grasslands are threatened by acidification and high nutrient levels in the topsoil. We investigated whether topsoil removal and soil perturbation in degraded sandy grasslands could lead to establishment of specialist species belonging to the threatened xeric sand calcareous grassland habitat. Restoration actions performed in 2006 resulted in increased soil pH and reduced nitrogen availability. We found early colonisztion of the perennial key species Koeleria glauca after both deep perturbation and topsoil removal, and high seedling establishment in topsoil removal plots 5 and 6 years following the restoration treatment (2011–2012). After topsoil removal, overall vegetation composition in 2012 had developed toward the undegraded community, with target species accounting for 20% of the community after topsoil removal, compared to 30% in the undegraded vegetation, and less than 1% in untreated controls. Deep perturbation led to 7% target species, while there were almost no effects of shallow perturbation 6 years following treatment. These results demonstrate that topsoil removal can promote colonization of target species of calcareous sandy grassland and highlights the importance of considering the regeneration niche for target species when implementing restoration measures .     

Vegetation Response Following Invasive Tamarisk (Tamarix spp.) Removal and Implications for Riparian Restoration

Using a retrospective study of tamarisk removal sites across five states in the southwestern United States, we investigated (1) decreases in tamarisk cover; (2) the effects of tamarisk removal on vegetation; and (3) whether cutting or burning tamarisk has differing effects on plant communities. Our study provides an important first step in recognizing the effects of removing a dominant invasive species on meeting long-term goals of riparian restoration. We found that (1) both cutting and burning reduced mean tamarisk foliar cover by 82–95%, and this reduction was sustained over time. (2) Native foliar cover was 2- to 3-fold higher on tamarisk removal sites, but total foliar cover remained 60–75% lower than on control transects. No trend toward increases in native cover was noted over time. When tamarisk was included in the analyses, diversity in tamarisk removal sites was 2- to 3-fold higher than in the control sites and vegetation communities differed between treated and untreated sites. When tamarisk was excluded from the analyses, diversity was not greater at tamarisk removal sites, and there were no community differences between the treated and untreated transects. Differences in diversity were found to be driven by differences in evenness; overall species richness did not change following tamarisk removal. Sites in the Mojave showed the strongest increase in native foliar cover and diversity, Chihuahuan-transition sites showed a slight increase, and sites on the Colorado Plateau showed no overall increase. (3) There were no differences between plant communities at burned and cut sites. Our research indicates that vegetation response to tamarisk removal is often negligible. Land managers should be prepared for persistent depauperate plant communities following tamarisk removal if additional restoration measures are not instigated.     

香港木兰开花生物学研究

对香港木兰的花果期物候、花朵结构、单花期、开花特性及花粉在离体培养和人工授粉条件下的萌发现象进行观察和研究。结果表明,该种的开花习性限制蜂类昆虫在其柱头可授期内进入花内传粉,为专一的甲虫传粉植物;花粉萌发时间长、开花不集中、花期适逢雨季都影响到昆虫的传粉活动和有效受精。     

铜陵市狮子山铜尾矿废弃地生态恢复过程中植被演替规律

通过对铜陵市狮子山铜尾矿废弃地植被的实地调查,探讨了该废弃地的植被状况及其植被恢复过程中的植物群落形成与演替的一般规律与特征.结果表明:目前废弃地入侵、定居植物共49种,隶属于15科38属,主要包括菊科(12种)、禾本科(11种)、豆科(8种)等.极端贫瘠和过高的重金属含量(特别是Cu、Cd,平均超出对照土样的20～30倍)是限制植物在废弃地定居的主要因素.全部植物中,一、二年生草本植物26种,多年生草本植物20种.风播种子和果实是废弃地植物繁殖体的主要来源.尾矿废弃地植物群落形成具有先锋植物的入侵、定居、群聚和竞争等过程,共形成了14种相对稳定的小群落,包括单优势种群落、次优势种群落和共优势种群落三种类型.伴随着尾矿废弃地植物群落的形成与演替,群落中物种丰富度增大,多样性指数呈增加趋势,而群落内植物种综合优势比间的差值趋于减小.     

Restoration of a Terrestrialized Soak Lake of an Irish Raised Bog: Results of Field Experiments

Soaks (areas of mesotrophic/minerotrophic vegetation within acid bog) add to the overall heterogeneity and biodiversity of raised bog landscapes due to the presence of flora and fauna communities not typically associated with acid bog systems. A field experiment was set up to investigate the potential to restore the minerotrophic and aquatic communities that previously occurred within a soak of an oceanic raised bog in Ireland, which has recently undergone acidification with the expansion of acid bog type vegetation. Three different treatments, control (intact sphagnaceous raft), permeable (sphagnaceous raft removed), and enclosed (sphagnaceous raft removed and plots isolated from surrounding surface water influence) were applied to a total of six plots (each measuring 4 × 4 m), each treatment consisting of two replicates. Within 3 years a sphagnaceous raft with similar vegetation to the surroundings had developed in both permeable plots, while aquatic communities similar to those that occurred at the site in the past had established within the enclosed pots. Our results show that with manipulation of local hydrology it is possible to recreate conditions suitable for aquatic plant communities that once characterized the site. The results also give an insight into the likely processes responsible for the initial terrestrialization of the entire soak over the past century. Application of the results in relation to the site and the widespread practice of restoring bog vegetation on degraded peatlands are discussed.