Hidden Costs of Passive Restoration

The first few years of tropical forest restoration can be expensive, especially when applied to expansive areas. In light of this, passive restoration has been recommended as a considerably cheaper or even free alternative. There are, however, both direct and indirect costs associated with passive restoration. First, the longer recovery time that is typically required in passive restoration can be perceived as project failure, especially when compared with nearby active restoration efforts. In the worst‐case scenario, this can lead to the premature termination of a project by a landowner who would like to see more rapid or visible results. Second, passive restoration may be viewed as land abandonment, and in developing nations where land tenure is not always strictly enforced this may invite unanticipated uses, such as ranchers who may unintentionally or intentionally allow livestock to take advantage of the “unused” forage grass, thus setting back recovery efforts. Lastly, passive restoration does have direct financial costs, including material costs for establishing fences and repairing them, and labor costs for site vigilance. These upfront investments may need to be made repeatedly in passive restoration efforts, and for a longer time period than for an active restoration project. Both the direct and indirect costs should be considered prior to choosing passive restoration as a strategy in a particular restoration project.     

退化生态系统的恢复与管理--兼论自然保护区在其中发挥的作用

生态系统退化与人口的增加及人类的活动有直接的关系。长期以来人类对自然生态系统的掠夺性利用造成了各类生态系统的退化,即人为原因是主要的,而自然原因是次要的。在退化生态系统的治理方面,关键要减少自然生态系统恢复演替中人为的压力,而大面积的土地可借助自然力恢复,恢复后的土地可发展成自然保护区,并开展生态旅游等非直接破坏性的活动。应充分考虑到社区的发展问题,解决人的生存出路并提高他们的生活质量,从而在根本上缓解对自然生态系统的压力。本文提出了“以地养地”并借助自然力恢复退化生态系统的模式,利用各种具体例子阐明了我们的观点。最后指出了中国古代先哲关于人与自然的关系原理至今在退化生态系统的恢复中仍然有着现实的指导意义。     

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.     

Soil properties of an Antarctic inland site: implications for ecosystem development

Inland Antarctic nunataks typically have simple physically weathered soils and limited ecosystem complexity. In this paper we present quantitative measurements of soil physical and chemical properties at one Antarctic nunatak. We measured pH, grain size, field capacity, soil organic carbon, phosphate, nitrate, ammonium and the cations magnesium, calcium and potassium along two transects. The data obtained indicated that very low levels of nutrients were present/available to biota, and that liquid water was absent, at least from the surface depths of soil, except during periods of active snow melt. Consequently, biological activity is severely limited. We conclude that, due to the climatic and microclimatic conditions at this location, the development of biological communities and soils is maintained in an extremely simple but still apparently stable ‘quasi climax’ state. Increased soil development and biological complexity can be expected if the contemporary rapid regional warming in the Antarctic Peninsula region continues.     

Restoration of Wet Fen Meadows by Topsoil Removal: Vegetation Development and Germination Biology of Fen Species

The present investigation was part of a fen restoration project, which deals with the rehabilitation of a deeply drained peat land used for intensive agriculture for more than 200 years. Consequently, the conditions for restoration are unfavorable. The hay of well‐developed fen meadows from nature reserves in the region appeared to contain enough viable seeds to act as a source for the development of target communities when spread out on bare peat after topsoil removal. Repeated vegetation analysis showed that a combination of topsoil removal and hay transfer resulted in the establishment of new populations in the target area for 70% of the species of the donor area. Germination conditions of fen species were investigated to determine the optimal combination for stimulating germination rates. Most fen species were found to be dormant, and it was shown that dormancy could be broken with fluctuating light and temperature cycles and stratification pre‐treatment.     

Science, Art, or Application—the "Karma" of Restoration Ecology

The present state of restoration ecology is far away from Bradshaw’s “acid test for ecology.” The conclusions drawn from the series of papers in this issue and from the Jena workshop suggest some directions in which the field may progress. More attention must be paid to the degraded state, which should be evaluated by its specific features and carefully analyzed before any restoration plan is laid down. Restoration goals have to be realistic, which includes the appreciation of globally changing conditions, resulting in a paradigm‐shift toward “forward‐restoration.” Basically, the transition from the degraded state conditions to the target state is a kind of succession that is manipulated by the application of goal‐orientated and system‐specific disturbances. Whenever possible, restorationists should step back and make use of naturally occurring succession, which requires a sophisticated restoration strategy, involving flexible management responses, multiple alternative target states, robust measurements for the restoration progress, and careful long‐term monitoring. The unique feature of restoration ecology is the involvement of socioeconomic decisions, and conceptual frameworks for ecological restoration have to implement the specific links to natural succession. To bridge the gap between ecological theory and on the ground restoration, it is essential that restoration practice is translated into the vocabulary and thinking of basic ecology. If all these aspects are integrated, ecological restoration as an application—and restoration ecology as an applied science—may develop into an acid test for our understanding of interactions between people and their environment, rather than for pure ecology.     

惠州西湖游浮植物群落对生态系统修复的响应

2004年对广东惠州西湖实施了生态系统修复示范工程,示范区目前沉水植物丰富,水体常年清澈见底。通过2008年6月至2009年5月对示范区和未进行生态修复的平湖逐月进行浮游植物调查,研究了浮游植物群落对湖泊生态系统修复的响应。结果表明,与未修复的平湖相比,示范区浮游植物数量及群落结构均发生了很大变化。示范区全年浮游植物平均生物量和细胞丰度分别为0.31 mg/L和2.75×106cells/L,均远低于未修复的平湖的3.27 mg/L和197.46×106cells/L;平湖中蓝藻在全年大部分时间占有绝对优势,一些热带富营养化水体中的代表种类（假鱼腥藻）成为优势种类;而示范区蓝藻不占优势,取而代之的是一些隐藻、硅藻和甲藻门的种类。另外,示范区浮游植物丰富度增加,年平均Margalef物种丰富度指数为3.70,显著高于平湖的2.68。因此,重建以沉水生植物为优势的生态系统是抑制浮游植物发展和改善湖泊水环境的有效途径。     

Implementation of Basic Studies in the Ecological Restoration of Surface-Mined Land

This paper focuses on attempts to encourage a new state of the art in the ecological restoration of surface‐mined land in Germany. On most of these sites, the application of traditional recultivation methods often destroys valuable ecological potential by leveling of the surface, ameliorating of nutrient‐poor substrates, and seeding or planting of species not suited to the present habitat conditions. Many studies have shown that even highly disturbed ecosystems, such as large mining areas, can regenerate spontaneously over long‐term periods. Colonization processes were influenced by the availability of diaspore sources as well as the suitability of sites for establishment. The predictability of succession could be improved by the identification of switch points in successional pathways depending on age and conditions of the sites. Based on the developmental potential, orientation by nature and biodiversity are selected as main targets for priority areas for nature conservation in mining sites. On priority areas restoration measures must be restricted to the use of near‐natural methods (e.g., application of fresh, diaspore‐rich plant clipping material, dumping of overburden with seed bank and vegetative propagules, seeding of site‐specific, local seed mixtures) that are very successful in preventing erosion and accelerating vegetation development. Despite the success of these methods, the transfer of knowledge between scientists, practitioners, and administrative organizations has proved to be insufficient. Therefore, one of the main tasks in ecological restoration must be the inclusion of all stakeholders involved in decision‐making processes and the establishment of a network of excellence to enhance the exchange of knowledge.     

Plant–plant interactions determine natural restoration of plant biodiversity over time,in a degraded mined land

Restoration of degraded environments is essential to mitigate adverse impacts of human activities on ecosystems. Plant–plant interactions may provide effective means for restoring degraded arid lands, but little is understood about these impacts. In this regard, we analyzed the effects of two dominant nurse plants (i.e., Artemisia sieberi and Stipa arabica) on taxonomic, functional, and phylogenetic diversity across different ages of land abandonment (i.e., control, recent, and old ages) in a limestone mine site in Iran. In addition, we considered two spatial scales: i) the plot scale (i.e., under 1m2 plots) and ii) the vegetation‐patch scale (i.e., under the canopies of nurse plants), to assess nurse plant effects, land abandonment ages, and their relative importance on biodiversity facets by performing Kruskal–Wallis H test and variation partitioning analysis. Our results indicated an increase in taxonomic, functional, and phylogenetic diversity at the plot scale, when considering the presence of nurse plants under old ages of land abandonment. Such significant differences were consistent with the positive effects of Artemisia patches on taxonomic diversity and Stipa patches on functional and phylogenetic diversity. In addition, we found a larger contribution from nurse plants than land abandonment age on biodiversity variation at both spatial scales studied. Therefore, these results indicate the importance of plant–plant interactions in restoring vegetation, with their effects on the presence of beneficiary species and their functional and phylogenetic relatedness depending on the nurse life forms under the stress‐gradient hypothesis.     

Effects of reclamation measures on plant colonization on lignite waste in the eastern Pyrenees,Spain

Abstract. This paper deals with vegetation establishment on waste dumps in the montane and submontane belts of the eastern Pyrenees, where submediterranean Quercus humilis forests, Pinus sylvestris forests and mesoxerophilous pastures make up most of the landscape; these are considered as target communities for reclamation. The waste consists of marl and lime regolith, very poor in nutrients and structure (Poch et al. 1989). The dumps were terraced in 1985–1986; some were left for spontaneous re‐colonization and others were reclaimed in various ways. In 1992 we took 36 vegetation samples on the dumps, based on the point quadrat procedure, to evaluate the colonization status and the differences between reclamation techniques. The samples were analysed on the basis of their species composition (ecological groups and multivariate analysis) and structural aspects (coverage, diversity, etc.). Reclamation treatment results varied widely, most of the dumps showing a low degree of naturalness. Colonizing vegetation ranged from a mixture of opportunist and stress‐resistant taxa, forming poorly covered surfaces on the dumps where colonization has been poor, to dense grasslands dominated by one (or a few) introduced competitive grass species, where reclamation procedures had been intensive. Sowing treatments, where pasture species were sown onto dumps, produced intermediate results, as resulting vegetation cover was similar to control plots and naturalness was low, but in a few cases they yielded more interesting swards, fairly dense and diverse, and including high numbers of spontaneous species. Choice of sown species and proximity to undisturbed vegetation accelerate succession.     

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.     

Modeling the Effects of Fire on the Long-Term Dynamics and Restoration of Yellow Pine and Oak Forests in the Southern Appalachian Mountains

We used LANDIS, a model of forest disturbance and succession, to simulate successional dynamics of forests in the southern Appalachian Mountains. The simulated environments are based on the Great Smoky Mountains landscapes studied by Whittaker. We focused on the consequences of two contrasting disturbance regimes—fire exclusion versus frequent burning—for the Yellow pine (Pinus L., subgenus Diploxylon Koehne) and oak (Quercus L.) forests that occupy dry mountain slopes and ridgetops. These ecosystems are a conservation priority, and declines in their abundance have stimulated considerable interest in the use of fire for ecosystem restoration. Under fire exclusion, the abundance of Yellow pines is projected to decrease, even on the driest sites (ridgetops, south‐ and west‐facing slopes). Hardwoods and White pine (P. strobus L.) replace the Yellow pines. In contrast, frequent burning promotes high levels of Table Mountain pine (P. pungens Lamb.) and Pitch pine (P. rigida Mill.) on the driest sites and reduces the abundance of less fire‐tolerant species. Our simulations also imply that fire maintains open woodland conditions, rather than closed‐canopy forest. For oaks, fire exclusion is beneficial on the driest sites because it permits oaks to replace the pines. On moister sites (north‐ and east‐facing slopes), however, fire exclusion leads to a diverse mix of oaks and other species, whereas frequent burning favors Chestnut oak (Q. montana Willd.) and White oak (Q. alba L.) dominance. Our results suggest that reintroducing fire may help restore decadent pine and oak stands in the southern Appalachian Mountains.     

Restoration of coastal dune slacks in the Netherlands

In order to stop the continuous decline of typical dune slack communities along the Dutch coast, restoration projects have been carried out since 1952. Restoration measures consisted of re-introducing traditional management techniques in dune slacks, such as mowing, grazing and sod removal, or constructing artificial dune slacks to compensate for lost biodiversity elsewhere. An analysis of successful and unsuccessful projects showed that constructing new dune slacks was not very successful for maintaining new populations of endangered dune slack species, since such projects were often carried out in areas where seed banks were depleted, while hydrological conditions and seed dispersal mechanisms were sub-optimal. The construction of sand dikes to prevent sea intrusion in large beach plains was, unintentionally, a temporary success for the establishment of many Red List species, although such measures often disrupted natural dune slack formation. Successful sites were all characterised by a regular discharge of calcareous groundwater provided by local or regional hydrological systems, where not very long ago populations of typical dune slack plants were present. Under such conditions, sod removal was a successful measure to create pioneer stages which were relatively stable, due to a very slow accumulation of organic matter in the topsoil. It is argued that new and more flexible coastal defence strategies can provide new opportunities for natural and relatively stable pioneer stages of dune slack formation, suitable for the long term preservation of endangered dune slack species.     

典型草原自然恢复演替过程中植物群落动态变化

以内蒙古巴林右旗退化典型草原为研究对象,采用空间序列代替时间序列的方法,探讨了在围封去除干扰条件下,退化典型草原自然恢复演替进程.研究结果表明,物种多样性在典型草原群落自然恢复过程中呈波动状变化,最高值出现在第6年,为3.3,随后又呈现下降趋势.丰富度和均匀度与物种多样性指数呈显著正相关,相关系数分别为0.848和0.912.地上生物量和物种多样性二者之间没有明显的线性关系,其相关系数为0.4813(P＞0.05).在演替的进程中,群落中主要植物种的优势地位发生了明显的替代变化.在恢复演替初期C4植物对地表的覆盖和有机物的输入起关键作用,而C3植物在后期对群落稳定起重要作用.1年生植物在典型草原恢复初期起着非常重要的作用,可覆盖地表,防止水土流失,并为群落输入大量养分,为其他植物定居创造了稳定良好的土壤环境.     

西沙群岛主要岛屿不同植被类型对土壤理化性质的影响

为了解海岛植被恢复过程中植物群落对土壤理化性质的影响,对西沙群岛的永兴岛和东岛上不同植被群落的土壤主要理化性质进行测定。结果表明,随着岛屿植被由藤草经灌木向乔木群落的过渡,土壤含水量由5.9%显著升高至14.2%;土壤微生物生物量碳、生物量氮分别由176.2和41.2 mg kg~(-1)显著升高至391.5和98.8 mg kg~(-1);而pH呈下降趋势。这表明随着植被的恢复,海岛土壤质量不断提高,生态系统渐趋稳定。     

黄土丘陵区恢复草地土壤团聚体组成及全氮分布特征

团聚体作为土壤基本结构单元,其各粒级全氮（TN）含量对土壤TN储量的贡献各不相同,而草地恢复过程中地上植被会影响土壤团聚体组成与各粒级TN的分布,这必然会对团聚体稳定性和土壤氮素累积产生影响。因此,以恢复10a、20a、30a、40a和50a草地和对照农田（CK）为研究对象,探究草地恢复过程中土壤团聚体氮素累积规律。结果表明：1）50年恢复过程中草地群落经历了茵陈蒿（Artemisia capillaries）→茵陈蒿+铁杆蒿（Artemisia stechmanniana）→铁杆蒿+兴安胡枝子（Lespedeza davurica）→铁杆蒿+本氏针茅（Stipa bungeanaTrin）→铁杆蒿+白羊草（Bothriochloa ischaemum）的演替过程,且草地群落物种多样性指数随恢复年限的增加呈先升后降的趋势,地上植物、细根和凋落物的碳和氮含量呈先上升后下降趋势。2）草地恢复过程中土壤pH和容重呈下降趋势,而土壤含水量呈先降后增趋势,土壤有机碳含量在恢复过程中显著增加（P<0.05）,土壤TN含量随恢复年限呈先增后降的趋势,而TN储量呈逐年增加趋势,恢复10-50a草地与CK相比增加了8.10%-118.92%。3）不同恢复年限草地群落土壤微团聚体（0.053-0.25 mm）占比最大,但随恢复年限增加呈下降趋势,而大团聚体（>2 mm）和中团聚体（0.25-2 mm）占比以及平均重量直径（MWD）和几何平均直径（GMD）呈上升趋势。4）不同恢复年限草地群落中团聚体TN含量最高,且各粒级团聚体TN含量随恢复年限呈先下降后上升趋势;草地群落微团聚体TN储量最高,大、中团聚体TN储量随恢复年限增加呈上升趋势,微、粘粉粒团聚体（<0.053 mm） TN储量随恢复年限增加出现波动;各粒级团聚体TN储量与地上植物、细根和凋落物生物量以及碳氮含量显著相关（P<0.05）。5）草地恢复过程中大团聚体对土壤TN储量的贡献率达70%,且大团聚体占比增加是大团聚体贡献率高的主要原因。总之,草地恢复有利于土壤稳定以及氮素累积。     

Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites

We address the question: under which circumstances can we rely upon spontaneous succession and when are technical measures more effective in restoration programs? To answer this question, the position of a disturbed site along the productivity–stress gradient was considered. The probability of attaining a target stage by spontaneous succession decreases toward both ends of the productivity–stress gradient, whereas the acceptance of technical measures generally increases. In correspondence with that, the monetary cost of restoration increases toward the ends of the gradient. Therefore, spontaneous succession is advocated especially if environmental site conditions are not very extreme.     

沸石对土壤养分生物有效性和土壤化学性质的影响研究

在花岗岩发育的赤红壤上进行的天然沸石混施化肥的盆栽试验研究结果表明,沸石提高了土壤养分的生物有效性,显著促进玉米的生长,增加玉米的生物量和提高了玉米对N,P,K的吸收量,15N示踪技术表明,沸石处理可以显著提高氮肥的利用率,两造玉米最高的氮肥利用率分别比对照提高28．8％和60．0％,土壤的分析结果表明,沸石处理也可提高土壤阳离子交换量,盐基饱和度和土壤pH值。     

Measuring Success: Evaluating the Restoration of a Grassy Eucalypt Woodland on the Cumberland Plain, Sydney, Australia

Abstract We compared the floristic composition and structure of restoration areas of eucalypt woodland with untreated pasture (control) and remnant vegetation (reference) in western Sydney. The restored areas comprised over 1,000 ha of abandoned pasture, which had been treated to reduce weeds and planted with seedlings of 26 native plant species raised from seed obtained locally from remnant vegetation. Plantings were carried out 0–9 years ago. Floristic composition was measured in quadrats using frequency scores and cover abundance. As far as possible treatments and restoration ages were replicated across sites. Ordination and analyses of similarity failed to distinguish the composition of restored vegetation from that of untreated pasture, which were both significantly different from that of remnant vegetation. There was a weak compositional trend with age of restored vegetation, but this was not in the direction of increasing resemblance to remnant vegetation. There was some evidence for convergence in structural features of restored with remnant vegetation, but this was at least partly attributed to plant growth. Subject to constraints imposed by the sampling design, environmental factors, and spatial variation were discounted as explanations for the results. The results therefore suggest either failure of restoration treatments or a restoration trajectory that is too slow to detect within 10 years of establishment. Our conclusions agree with those of similar studies in other ecosystems and support: (1) the need to monitor restoration projects against ecological criteria with rigorous sampling designs and analytical methods, (2) further development of restoration methods, and (3) regulatory approaches that seek to prevent damage to ecosystems rather than those predicated on replacing losses with reconstructed ecosystems.