Forest Restoration Approaches Research Articles

Historical trajectory of restoration practice and science across the Brazilian Atlantic Forest

Restoration is fundamentally a hopeful intervention that can meaningfully improve the condition of human‐degraded and destroyed ecosystems. Both restoration science and practice have gained special attention given the recently declared UN Decade of Ecosystem Restoration. Here, we present an overview of the historical development of forest restoration on the Brazilian Atlantic Forest with an emphasis in methodological and technical assumptions. We gathered information from primary and secondary studies to show how forest restoration concepts and strategies evolved over the years. Given the importance of reviews for informing management and policy as well as research, our study provides a summarized information on forest restoration approaches or practices that can help practitioners and non‐initiated to understand how this field evolved in Brazil and how lessons learned can be useful for forest restoration in other countries.

Variations in litter-soil properties between planted and naturally restored forests drive microbial community structure and function

How forest restoration can affect soil microbial composition and functionality remains unclear, limiting our ability to evaluate restoration approaches. Here, we used metagenomes, 16S rRNA, and ITS gene sequencing to distinguish the composition and functional attributes of soil microbial communities between plantation forest of Pinus massoniana (PF) and naturally restored secondary forest (SF) in their organic horizon and mineral soil from a typical karst region in Southwest China. Our results showed that fungal communities differed more than bacterial communities between PF and SF, while the differences in archaeal communities were not significant. The most abundant fungal phylum in both mineral soil and organic horizon was Ascomycota at SF and Basidiomycota at PF, respectively. The PF soil had lower nitrogen (N) cycling gene abundance and lower inorganic N availability compared to SF soil probably because of the poor soil and lower litter quality. The SF soil had higher abundances of genes associated with labile carbon (C) (i.e., starch, hemicellulose, cellulose, pectin, and chitin) degradation compared with PF soil, but lower abundances of genes responsible for recalcitrant C (i.e., lignin and aromatics) degradation, which was strongly correlated with the litter properties. Simultaneous effects of soil and litter variables explained >50 % of the variation in microbial community structure and functional gene composition; soil nitrate-N had the strongest effect on the soil bacterial and fungal community structure. Our results highlight the superiority of naturally restored secondary forests for improving both soil fertility and soil microbial-mediated C and N cycling functions, which can support forest managers in selecting forest restoration approaches that optimize C and N storage in forest stands.

亚热带退化森林不同恢复方式对土壤团聚体胶结物质及稳定性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 亚热带退化森林不同恢复方式对土壤团聚体胶结物质及稳定性的影响 DOI: 10.5846/stxb202204211092 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(32001298); 湖北省教育厅重点项目(D20201001); 大学生创新训练项目(S202110512085) Effects of different restoration approaches of subtropical degraded forests on bonding materials and stability of soil aggregate Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:退化森林的恢复一直是林业和生态学研究的热点。良好的森林土壤结构有助于林木生长发育,作为土壤最基本的结构单元,土壤团聚体组成和稳定性是衡量土壤肥力和质量的重要指标,其团聚结构的形成依靠土壤胶结物质。然而,土壤胶结物质与团聚体稳定性之间的关系尚不确定。为探明亚热带退化森林的不同恢复方式对团聚体稳定性的影响及其潜在机制,以自然恢复的次生林为对照(CK),选取了亚热带三种常见的人工林:一代杉木林(P1)、二代杉木林(P2)和黄山松林(P3),测定土壤团聚体稳定性及其胶结物质的含量,并分析了各胶结物质对团聚体稳定性的影响。研究发现:不同森林恢复方式显著影响了土壤pH值、碳氮比、速效磷含量、团聚体的组成和稳定性。所有森林类型中,三种人工林的团聚体稳定性显著高于CK,P2的大团聚体所占比例最大,团聚体稳定性最高。恢复方式显著影响了土壤游离氧化铁含量、菌根密度和易提取球囊霉素相关土壤蛋白(EEG)含量。团聚体稳定性与游离氧化铁含量、菌根密度呈正相关,但与EEG含量呈负相关。研究结果表明,亚热带退化森林的人工恢复比自然恢复更有助于增强土壤团聚体稳定性,土壤游离氧化铁、菌根密度和EEG是显著影响团聚体稳定性的胶结物质。 Abstract:The restoration of degraded forest has been a hot topic in forestry and ecology. As a basic structural unit of soil, soil aggregate composition and stability are important indicators of soil fertility and quality, and the formation of soil aggregate relies on aggregate bonding materials. However, the relationship between aggregate bonding materials and aggregate stability is uncertain. To explore the effects of different restoration approaches of degraded subtropical forests on aggregate stability and its underlying mechanisms, we compared the secondary forest (natural restoration) as a control (CK), with three different common subtropical plantations which were: (1) first-generation Cunninghamia lanceolata (P1), (2) second-generation C. lanceolata (P2), and a Pinus. taiwanensis plantation (P3). We measured the aggregate stability and the contents of different aggregate bonding materials, and then analyzed the influence of these materials on soil aggregate stability. Results showed that forest restoration approach significantly affected soil pH, C/N, available phosphorus, as well as the composition and stability of aggregate. Among all the forests, the aggregate stability was significantly lower in CK than in the other three plantations, and P2 had the greatest proportion of large aggregates and the highest aggregate stability. The forest restoration approach also significantly affected soil free Fe oxide content, mycorrhizal density, and easily extractable glomalin-related soil protein (EEG). Aggregate stability was positively correlated with free Fe oxide content and mycorrhizal density, but negatively correlated with EEG. For subtropical degraded forests, the results indicated that artificial restoration was better than natural restoration to enhance soil aggregate stability, with soil free Fe oxide, mycorrhizal density and EEG being the main bonding materials that significantly affected the aggregate stability. 参考文献 相似文献 引证文献

Effects of Post-Fire Timber Harvest and Mastication on Shrub Regrowth in the Sierra Nevada Mountains: A Lake Tahoe Case Study

Increasingly large high-severity wildfires in dry forests of the western United States have led to concern about how best to regenerate new forests after wildfires. Harvesting fire-killed trees, burning woody debris, and tree planting are commonly used reforestation strategies. This study evaluated the effects of a novel forest restoration approach that involved masticating un-merchantable dead trees and spreading the woody debris generated across the site to prevent erosion from the 2007 Angora Fire in Lake Tahoe, California. Woody material covered 82% of the site after treatment, with an average depth of 6.6 cm, and volume of 190 tonnes per hectare. We found that this treatment reduced shrub regrowth, compared to an untreated area nearby, and that shrub regrowth was inversely related to fuel depth. Seven years after the fire, shrub cover averaged only 50% on treated plots compared to 92% on untreated plots. The tallest shrubs averaged 69 cm in height on the treated site compared to 114 cm on nearby untreated sites. Tree seedlings planted on the treated site averaged 141 cm in height, well above the height of the shrubs. Advantages of this approach include controlling erosion while reducing drought stress, reducing the potential for weed introduction, and reducing the need for herbicide to control shrub competition. Although leaving a layer of woody material where new trees have been planted does constitute a fire hazard, so too does a vigorous shrub layer. Managers should consider and weigh these factors when deciding on a post-fire reforestation strategy.

The biodiversity and ecosystem service contributions and trade-offs of forest restoration approaches.

Forest restoration is being scaled up globally to deliver critical ecosystem services and biodiversity benefits; however, there is a lack of rigorous comparison of cobenefit delivery across different restoration approaches. Through global synthesis, we used 25,950 matched data pairs from 264 studies in 53 countries to assess how delivery of climate, soil, water, and wood production services, in addition to biodiversity, compares across a range of tree plantations and native forests. Benefits of aboveground carbon storage, water provisioning, and especially soil erosion control and biodiversity are better delivered by native forests, with compositionally simpler, younger plantations in drier regions performing particularly poorly. However, plantations exhibit an advantage in wood production. These results underscore important trade-offs among environmental and production goals that policy-makers must navigate in meeting forest restoration commitments.

Sixty-five years of forest restoration in Nepal: Lessons learned and way forward

The increasing incidence of forest and land degradation is affecting billions of people, and causing loss of biodiversity and ecosystem services. Realizing the importance of forest restoration in moderating those impacts, various global and regional forest restoration initiatives (including Bonn Challenge 2011 and UN Decade on Ecosystem Restoration (2021–2030) have been launched. But the gap between restoration commitments and their ground realities is becoming a huge challenge because of the limited knowledge on forest restoration approach as well as underlying socio-economic and ecological factors impacting the restoration undertaking. Moreover, few studies have comprehensively looked at institutional, socio-economic, and ecological aspects of forest restoration in a common framework. By employing a systematic review of the literature (n = 64), review of policies, plans and project reports (n = 58) and expert survey (n = 22), this study has navigated the rise and fall of Nepal’s 65 years of forest restoration practices. Our study found that Nepal’s forest restoration interventions from 1956 to the early 1980s got mixed results because of the limited integration of socio-economic and ecological concerns in restoration programs. However, forest restoration works after the mid-1980 s charted a more successful pathway because of (1) policies favouring decentralized decision making and local institutions; (2) devolution of rights and responsibilities; (3) firmed commitment for and adoption of multistakeholder partnership for the forest and landscape restoration; (4) recognition of multifunctionality of forest ecosystems; (5) accommodation of socio-economic and ecological concerns in restoration program; 6) adoption of multiple restoration approaches at multiple scales; and 7) capacity development and extension services. As institutional, socio-economic, and ecological factors are often been overlooked in forest and landscape restoration initiatives, the inferences we made and suggestions we provided can inform the policymakers and practitioners (of Nepal and other countries) in translating regional and global restoration commitments into action.

Wild bees benefit from structural complexity enhancement in a forest restoration experiment

Structural complexity enhancement (SCE) is a forest restoration approach aiming to maintain or increase biodiversity in managed, secondary forests. Whether the diversity of wild bees also benefits from such restoration measures in temperate forests is not well studied. We conducted a restoration experiment in secondary spruce forests on twelve 50 × 50 m plots in the Black Forest National Park in Baden-Württemberg, Germany. SCE was carried out on half of the study plots (six) in 2016 comprised create deadwood through girdling and uprooting of 20 spruce trees per plot and thus initiating small gaps. The other six plots were used as control plots with no SCE. Wild bees were sampled in June 2018 and 2019 using coloured pan traps. We hypothesized that creation of deadwood influences bee abundance and richness, especially of aboveground-nesting bees, and thus would also change bee community composition at the plot scale. Furthermore, we assessed the influence of bilberry (Vaccinium myrtillus L.) cover in the plots and areas of meadows and roads of the intermediate surrounding on wild bees.Estimated species richness was higher on restored plots than on control plots. Deadwood originating from restoration increased the number of aboveground-nesting, solitary and cuckoo bee individuals. In particular standing deadwood had a positive impact on bee individuals. Increased bilberry cover and nearby meadow areas increased abundance and richness of the bee community.We conclude that creation of deadwood in coniferous forest is a promising restoration measure to promote solitary, aboveground-nesting bees. Increased light availability through restoration, which promotes bilberry flowering, is also beneficial for bees.

Exotic eucalypts: From demonized trees to allies of tropical forest restoration?

Abstract International forest landscape restoration commitments have promoted the restoration of millions of hectares of degraded and deforested lands globally, but few forest restoration approaches provide both ecologically‐sound and financially‐viable solutions for achieving the spatial scale proposed. One potential revenue source for restoration is selective harvesting of timber, a product for which there is a clear global market and increasing demand. The use of commercially valuable exotic trees may attract farmers to restoration, but can be a major concern for ecologists. Here, we present results collected over 7 years from experimental studies at three sites across the Brazilian Atlantic Forest to assess the impacts of incorporating exotic eucalypts as a transitional stage in tropical forest restoration on above‐ground biomass accumulation, native woody species regeneration and financial viability. Biomass accumulation was nine times greater in mixed eucalypt‐native species plantations than native only plantings due to fast eucalypt growth. Nonetheless, the growth of native non‐pioneer trees was not affected or only slightly reduced by eucalypts prior to logging. Eucalypts did not negatively affect the natural regeneration of native woody species before or after eucalypt logging. Canopy cover regrew quickly but was slightly lower a year following logging in mixed eucalypt‐native species plantations. Natural regeneration richness and planted non‐pioneer growth were similar across treatments in the post‐logging period. We found higher variation of biomass accumulation and native species regeneration among sites than between plantation types within sites. The income from eucalypt wood production offset 44%–75% of restoration implementation costs. Synthesis and applications. Many of the negative effects attributed to eucalypts on the growth and natural regeneration of native trees depend on features of the production system, landscape structure, soil, and climate in which they are grown, rather than the effects of eucalypts per se. In Brazil's Atlantic Forest region, exotic eucalypts can become important allies of tropical forest restoration, and their use and investment opportunities should be considered within the portfolio of options supported by public and private funding and policies.

Spatial congruence among indicators of recovery completeness in a Mediterranean forest landscape: Implications for planning large-scale restoration

Natural regeneration has been proposed as a cost-effective forest restoration approach for both small and large-scale initiatives. However, attributes for assessing the success of forest restoration through natural regeneration may vary among them in spatial patterns depending on the scale of analysis and on environmental gradients. Here we analysed the spatial patterns of recovery completeness (i.e. how similar attributes in restored forests are to the same attributes in reference forests) in response to environmental factors in a Mediterranean forest landscape of Central Chile. We evaluated (1) forest recovery completeness using basal area (BA), quadratic mean diameter (QMD), adult species density (ASD), adult species richness (ASR), and seedling species richness (SSR); (2) the spatial congruence of recovery completeness estimated by each of these indicators; and (3) the environmental factors potentially shaping these spatial patterns. We used field measurements and geospatial information sources to quantify and predict indicator responses by fitting boosted regression tree models. To assess the spatial congruence of predictions we overlaid high-level recovery completeness values for all indicators. Overall recovery completeness in the study area was 72.7%, suggesting positive prospects for attaining fully restored forests. Recovery completeness had a resulted higher for diversity (92.3%−99.6%) than structural forest attributes (33.5%−76.9%); however, spatial congruence among recovery indicators was low due to the uneven spatial responses of each indicator. The maximum potential spatial congruence was <10%, and was predicted only by two environmental variables (soil bulk density and slope). Our results suggest that low spatial congruence among forest recovery indicators may hinder the monitoring of restoration at large scales. The implications of such divergence in defining restoration success can be enormous given the current global challenge of forest restoration. Although our research was tested in a threatened region of global importance, our results may have wider significance for restoration planning providing cautionary notes and recommendations for the appropriate use of forest recovery indicators when monitoring large-scale restoration projects.

Forest restoration approaches affect soil compositions of lignin, substituted fatty acids, and lignin degradation-associated genes

The study of soil microorganisms and the composition of organic carbon is important for understanding the dynamics of soil organic carbon. The means by which forest restoration approaches might affect the soil composition of lignin, substituted fatty acids,11substituted fatty acids, SFA and the lignin degradation genes, remain understudied. We hypothesized that the soils of naturally restored forests have more abundant and stable lignin, SFA, and lignin degradation genes than those of artificially restored plantations. We analyzed the compositions of lignin, SFA, and the lignin degradation genes in soils restored with natural secondary forests, native species plantations, and introduced species plantations. We found that the extractable lignin content, leaf-derived SFA, leaf- to root-derived SFA ratio, and lignin oxidation state were higher in natural secondary forests than in plantations. The abundances of genes involved in glyoxal oxidase, lignin peroxidase, and manganese peroxidase were higher in the soils of natural secondary forests than in those of the two plantation types. No significant differences in the above indices were found between soils of native and introduced plantations. Nutrients and lignin oxidation state, including tree richness, litter stock, available nitrogen, combined clay and silt content, syringyl-based lignin to vanillyl-based lignin ratio, syringic acid to syringaldehyde ratio, and SFA content significantly affected the composition of genes involved in lignin degradation. Nutrients and lignin oxidation state explained 41.9% of the variation in the composition of lignin degradation genes. The lower lignin oxidation state, higher nutrient availability, and higher aboveground inputs led to a higher abundance of lignin degradation genes in the soils of natural secondary forests than in those of the plantations. These results provide insight into the effects of forest restoration approaches on soil carbon sequestration.

Early seedling establishment of endangered and valuable tree species in cloud forest restoration plantings

Tropical montane cloud forests (TMCF) host high biodiversity and endemicity and are severely threatened by illegal selective logging, deforestation, fragmentation and climate change. The fragments of TMCF present high heterogeneity over short spatial intervals and a regional forest restoration approach must therefore incorporate seedling performance throughout the TMCF elevation range. We examined early seedling establishment in 12 endangered and valuable TMCF species in the understory of unplanned selectively logged TMCF and assessed the influence of elevation and canopy cover on seedling performance. Tree seedlings (10-18 mo-old) were transplanted into restoration plantings in 6 forest sites along an elevation range (1,250 to 1,995 m) in Veracruz, Mexico. In each forest, 30 seedlings per species were planted and their survival and relative growth rates in height (RGRh) and basal stem diameter (RGRd) recorded, along with canopy cover. Survival was high for all species after one year (81.1 to 99.4%) and was unaffected by elevation. Canopy cover positively affected the survival probability of 3 species. Both RGRh and RGRd decreased at lower elevations in 4 species; however, overall growth rates were positive. Our results indicate a positive early seedling establishment response in the evaluated tree species under the TMCF canopy (66-97% of canopy cover).

Is applied nucleation a straightforward, cost‐effective forest restoration approach? Counter‐response to Holl and Zahawi (2018)

Holl and Zahawi (2018) agree on a number of approaches that we describe in a local case study of tropical montane cloud forest restoration in Mexico. However, they contend our argument that most applied nucleation projects have taken place in tropical lowlands as a mistake. They also provide data on the per‐hectare cost of restoration projects in Costa Rica and compare it to a higher cost figure of plantation‐style reforestation, a view contrary to ours. Last, Holl and Zahawi recognize that applied nucleation requires specialized personnel, but imply that the amount of training needed for this endeavor is not very different than what is required to implement other forest recovery projects. In this counter‐response, we provide some refinements to our original opinion and offer further information in support to our perspective.

Applied nucleation is a straightforward, cost‐effective forest restoration approach: reply to Ramírez‐Soto et al. (2018)

We agree with Ramírez‐Soto and colleagues that applied nucleation can be an effective approach for tropical forest restoration both in lowland and higher elevation tropical forests. We also contend that it is cheaper than standard plantation‐style plantings and is straightforward to train personnel to implement this approach.

Testing heterogeneity–diversity relationships in tropical forest restoration

Restoring small-scale habitat heterogeneity in highly diverse systems, like tropical forests, is a conservation challenge and offers an excellent opportunity to test factors affecting community assembly. We investigated whether (1) the applied nucleation restoration strategy (planting tree islands) resulted in higher habitat heterogeneity than more homogeneous forest restoration approaches, (2) increased heterogeneity resulted in more diverse tree recruitment, and (3) the mean or coefficient of variation of habitat variables best explained tree recruitment. We measured soil nutrients, overstory and understory vegetation structure, and tree recruitment at six sites with three 5- to 7-year-old restoration treatments: control (no planting), planted tree islands, and conventional, mixed-species tree plantations. Canopy openness and soil base saturation were more variable in island treatments than in controls and plantations, whereas most soil nutrients had similar coefficients of variation across treatments, and bare ground was more variable in control plots. Seedling and sapling species density were equivalent in plantations and islands, and were substantially higher than in controls. Species spatial turnover, diversity, and richness were similar in island and plantation treatments. Mean canopy openness, rather than heterogeneity, explained the largest proportion of variance in species density. Our results show that, whereas canopy openness and soil base saturation are more heterogeneous with the applied nucleation restoration strategy, this pattern does not translate into greater tree diversity. The lack of a heterogeneity-diversity relationship is likely due to the fact that recruits respond more strongly to mean resource gradients than variability at this early stage in succession, and that seed dispersal limitation likely reduces the available species pool. Results show that planting tree islands facilitates tree recruitment to a similar degree as intensive plantation-style restoration strategies.

南方红壤区3种典型森林恢复方式对植物群落多样性的影响

Plant diversity has important ecosystem function in forest ecosystem.Forest restoration approaches can impact plant diversity,especially the understory plant diversity.We studied the floristic characteristics,plant community structure and diversity of three forest restoration approaches in red soil region of southern China,which included introduced species slash pine(Pinus elliottii) plantations,native species Masson pine(Pinus massoniana) plantations and natural secondary forests.For each forest restoration approach,a total of 15 independent plots were surveyed.On each plot,three 10 m × 10 m subplots of area were surveyed for trees′ abundance,height and diameter at breast height.Within each tree subplot,one to two shrub quadrates(5 m × 5 m) and one to three herb quadrates(1 m × 1 m) were surveyed for plant species abundance.A total of 127 tree subplots,238 shrub subplots and 357 herb subplots were effectively surveyed for plant community structure.The results showed that:(1) 155 species(which belong to 160 genera and 86 families),137 species(which belong to 97 genera,59 families) and 226 species(which belong to 160 genera,86 families) were identified in slash pine plantations,Masson pine plantations and natural secondary forests,respectively.Dominant species in these 3 forest restoration approaches varied in tree,shrub and herb layers.Dominant species in Masson pine plantations were more similar to that of natural secondary forests compared with that of slash pine plantations.In tree layer,the dominant plant in slash pine plantations was only P.elliotti.Similarly,the dominant plant in Masson pine plantations was only P.massoniana.The dominant species in natural secondary forests belong to Fagaceae,Lauraceae and Theaceae.In shrub layer,the dominant plants were Verbenaceae,Gramineae,Hamamelidaceae,Theaceae and Euphorbiaceae for slash pine plantations;Hamamelidaceae,Verbenaceae,Theaceae,Fagaceae and Myrtaceae for Masson pine plantations;Fagaceae,Hamamelidaceae,Theaceae,Rosaceae,Rubiaceae and Myrtaceae for natural secondary forest.In herb layer,the dominant plants were Gramineae,Gleicheniaceae and Thelypteridaceae for slash pine plantations;Gleicheniaceae,Hamamelidaceae,and Dryopteridaceae for Masson pine plantations;Myrsinaceae,Gramineae,Dryopteridaceae,Cyperaceae and Rubiaceae for natural secondary forests;(2) natural secondary forests had more flora types(21 flora types) than Masson pine plantations(16 flora types) and slash pine plantations(18 flora types),and had higher ratio of temperate flora.Natural secondary forests had more unique flora types in comparison with Masson pine plantations and slash pine plantations;(3) forest restoration approach had significant effects on forest community diversity.In tree,shrub and herb layer,natural secondary forest had higher species richness and Shannon-Wiener diversity index than Masson pine plantations and slash pine plantations.There was no significant difference in these indexes between slash pine plantations and Masson pine plantations;(4) multivariate analysis showed that these three reforestation approaches differed significantly in their species composition.Moreover,compared with slash pine plantations,the community composition of Masson pine plantations was more similar to the natural secondary forests.In conclusion,natural restoration is an important forest restoration approach since it was better than artificial plantations of P.massoniana and P.elliottii,yet the native species of P.massoniana plantations were superior to the introduced species of P.elliottii plantations in maintaining plant community structure.

Impacts of reforestation approaches on runoff control in the hilly red soil region of Southern China

Vegetation structure and soil properties are not only correlated with forest management practices, but also affect soil and water loss significantly. To estimate the long-term influences of regenerating forest cover on soil and water loss from degraded land, the runoff and soil loss in the context of different forest restoration approaches, including a control plot (CL) and plantations of slash pine (Pinus elliottii), Chinese fir (Cunninghamia lanceolata), tea-oil camellia (Camellia oleifera), and natural secondary forest, were monitored in runoff plots over a 4-year period (2000–2003) in a hilly red soil region in Southern China. Relevant ecological factors and management intensity, were also measured. The results indicated that the four forest restoration approaches decreased surface runoff by 63.0–88.1% and soil erosion by 75.5–97.1% compared to the control. Moreover, runoff and soil erosion in tea-camellia plantation (TCP) and natural secondary forest (NSF) plots were significantly lower than with other treatments. Canopy cover, litter fall, plant roots, plant life forms, soil properties, and vegetation structure are important ecological factors that determine the magnitude of soil loss. Vegetation structure and plant life forms are the main factors reducing surface runoff and the movement of sediments. Effective control of soil and water loss in NSF and TCP are closely related to multiply stratified communities and the presence of specific plant life forms (the herbaceous keystone species Dicranopteris linearis), respectively. In addition, the above mentioned factors were sensitive to forest management patterns, including improper mechanical cultivation. Management practices should attempt to minimize disturbances to these factors to control runoff and soil erosion in each forest management unit. In particular, mechanical cultivation should loosen the soil around the base of a tree only, instead of over the entire ground surface, in the early stages of forest restoration.

Effects of regenerating forest cover on soil microbial communities: A case study in hilly red soil region, Southern China

The stability and function of a soil ecosystem depends on the cycling of nutrients by the soil microbial community. To evaluate the effects of regenerating forest cover on the function of microbial community, the differences of four forest restoration approaches, including plantations of slash pine, Chinese fir, tea-oil camellia and natural secondary forest, in soil microbial community size, activity and metabolic diversity were measured by microbial biomass and metabolic diversity (BIOLOG) assays in a hilly red soil region, Southern China. Native soils were sampled and assessed with 0–20 and 20–40 cm layers. Results showed that significant differences ( p < 0.05) were found in soil microbial biomass among four forest restoration approaches. It was highest in the soil of natural secondary forest, medial in the plantations of tea-oil camellia and Chinese fir and the least in slash pine plantation. Principal component analysis (PCA) further revealed consistent differences of the metabolic diversity patterns in 0–20 cm soil, but not for Chinese fir plantation, tea-oil camellia plantation and natural secondary forest in 20–40 cm soil. Average well colour development (AWCD) and indices of richness and diversity showed significant difference in the four forest restoration approaches. The variable tendency of the indicators was the same as microbial biomass. These suggested that the ability to utilize sole-carbon-source and functional diversity (metabolic diversity) for soil microbial community were stronger in natural secondary forest than that in plantations. Altogether, microbial biomass and metabolic diversity patterns in 0–20 cm soil of natural secondary forest were dominant, comparing with that of three plantations, viz. slash pine plantation, Chinese fir plantation and tea-oil camellia plantation. While in 20–40 cm soil there were no recognizable differences for above indicators among four vegetation types. Factors affecting the structure and function of soil microbial community appeared to be linked closely with artificial tending, soil and water loss, root biomass and litter production. The information gathered from the studies can be used to baseline data for forest restoration projects.

How different reforestation approaches affect red soil properties in southern China

AbstractSignificant differences were found in soil physicochemical and biological effects between various forest restoration approaches of a hilly red‐soil region, southern China. Soil quality was the highest in natural secondary forest (0·95), while in sites revegetated with tea‐oil camellia (Camellia oleifera), Chinese fir (Cunninghamia lanceolata) and slash pine (Pinus elliottii) and control sites, integrated soil quality indices were 0·68, 0·55, 0·36 and 0·04 respectively. The lower soil quality of plantations and controls resulted from increased disruption of soil physical structure, lower quality litter fall, lower litter fall production, reduction in microbial biomass, decline of microbial function and loss of soil nutrients due to periodically artificial tending and accelerated soil erosion. Improvement in soil physicochemical properties and enhanced soil microbial function at a natural secondary forest site demonstrated the inherent restoration of these soils. Hence, natural restoration, as well as reducing human disturbance, is a better approach to improving soil properties than returning farmland to planted woodlands. Copyright © 2005 John Wiley &amp; Sons, Ltd.

ECOLOGICAL RESTORATION OF SOUTHWESTERN PONDEROSA PINE ECOSYSTEMS: A BROAD PERSPECTIVE

The purpose of this paper is to promote a broad and flexible perspective on ecological restoration of Southwestern (U.S.) ponderosa pine forests. Ponderosa pine forests in the region have been radically altered by Euro-American land uses, including livestock grazing, fire suppression, and logging. Dense thickets of young trees now abound, old- growth and biodiversity have declined, and human and ecological communities are in- creasingly vulnerable to destructive crown fires. A consensus has emerged that it is urgent to restore more natural conditions to these forests. Efforts to restore Southwestern forests will require extensive projects employing varying combinations of young-tree thinning and reintroduction of low-intensity fires. Treatments must be flexible enough to recognize and accommodate: high levels of natural heterogeneity; dynamic ecosystems; wildlife and other biodiversity considerations; scientific uncertainty; and the challenges of on-the-ground im- plementation. Ecological restoration should reset ecosystem trends toward an envelope of ''natural variability,'' including the reestablishment of natural processes. Reconstructed historic reference conditions are best used as general guides rather than rigid restoration prescriptions. In the long term, the best way to align forest conditions to track ongoing climate changes is to restore fire, which naturally correlates with current climate. Some stands need substantial structural manipulation (thinning) before fire can safely be reintro- duced. In other areas, such as large wilderness and roadless areas, fire alone may suffice as the main tool of ecological restoration, recreating the natural interaction of structure and process. Impatience, overreaction to crown fire risks, extractive economics, or hubris could lead to widespread application of highly intrusive treatments that may further damage forest ecosystems. Investments in research and monitoring of restoration treatments are essential to refine restoration methods. We support the development and implementation of a diverse range of scientifically viable restoration approaches in these forests, suggest principles for ecologically sound restoration that immediately reduce crown fire risk and incrementally return natural variability and resilience to Southwestern forests, and present ecological perspectives on several forest restoration approaches.