Ecological Restoration Strategies Research Articles

Selection of Different Trees/Shrubs Species for Rehabilitation of Degraded Lands in Wag-Lasta Area, Northeastern Ethiopia

Due to human and livestock population pressure, land degradation is the main problem in many part of Ethiopia. To avert the situation, tree and shrub species selection on degraded lands are valuable tool for ecological restoration. Therefore, the aim of this study was to select the best performing tree and shrub species in three agro-ecological zones of Waglasta area, Ethiopia. The experiment was conducted in randomized block design with three replications in highland, mid altitude, and lowland sites. For total experimental setup 21 (seven for lowland, eight for mid altitude and six for highland) tree and shrub species were used. Growth and survival rate data were collected every 3 months interval for one year and every 6 months up to the end of the experiment. The result indicated that L. pallid (2.52 ± 0.19 m) at lowland site, Acacia senegal (1.32±0.23 m) at mid altitude and Acacia decurrens (4.0 ± 0.46 m) at highland site had shown better performance in height. Similarly, Moringa stenopetala at lowland, Jatropha carcus at mid altitude and Acacia saligna at highland site had shown 8.63 ± 2.37 cm, 3.1 ± 0.2 cm and 7.06 ± 0.75 cm performance in root collar diameter, respectively. However, the survival rate was higher for A. senegal (43 ± 7%) and M. stenoptella (44 ± 17%) at lowland site, A. senegal (98 ± 2%) at mid altitude and A. saligna (63.9 ± 20.0%) at highland site. Therefore, to restore degraded lands and to support the on-going land rehabilitation programs of Wag-lasta area, we recommend A. senegal and M. stenoptella for lowland site, A. senegal for mid altitude areas and A. saligna for highland site of Lalibela, Abergele and Sekota and similar agro-climatic zones. However, additional studies regarding soil nutrient dynamics, fostering effect and tree nursing should be integrated to develop sound ecological restoration strategies in the growth corridor as well as in the region.

Evaluating ecosystem functioning following river restoration: the role of hydromorphology, bacteria, and macroinvertebrates

Ecological restoration of freshwater ecosystems is now being implemented to mitigate anthropogenic disruption. Most emphasis is placed on assessing physico-chemical and hydromorphological properties to monitor restoration progress. However, less is known about the structural integrity and ecosystem health of aquatic ecosystems. In particular, little is known about how ecosystem function changes following river habitat restoration, especially in China. Leaf litter decomposition can be used as an indicator of stream ecosystem integrity. Therefore, the leaf breakdown rate was measured to assess the ecosystem function of restored rivers. By comparing leaf breakdown rates in urban rivers undergoing habitat restoration with that in degraded urban rivers and rivers in forested areas (i.e., reference conditions), we aimed to determine: (i) how habitat restoration affected leaf litter decomposition? (ii) the relationship between leaf litter decomposition to both environmental (habitat and physico-chemical variables) and biological factors (benthic communities), and (iii) identify the factors that contribute most to the variance in leaf litter breakdown rates. The results demonstrated a significant increase in leaf breakdown rate (120% in summer and 28% in winter) in the restored rivers compared to the degraded rivers. All environmental and biotic factors evaluated contributed synergistically to the differences in leaf litter decomposition among the three river types. The role of macroinvertebrates, mainly shredders, appeared to be particularly important, contributing 52% (summer) and 33% (winter) to the variance in decomposition, followed by habitat characteristics (e.g. substrate diversity, water velocity; 17% in summer, 29% in winter), physico-chemical variables (e.g. nutrient and organic pollutants; 11% in summer, 1% in winter) and biofilm bacteria (0% in summer, 15% in winter). Habitat restoration positively affected the structure and function of the previously degraded streams. Knowledge on controlling variables and their attribution to changes of ecosystem functioning provides guidance to assist the future planning of ecological restoration strategies.

Ecological network construction of the heterogeneous agro-pastoral areas in the upper Yellow River basin

The increasing landscape heterogeneity in the agro-pastoral areas and the contradiction between the development and biodiversity conservation is becoming more and more prominent, especially in Northwest China. Rational ecological network construction has become an important issue for ecological restoration and ecological security pattern strategy. Taking a typical agro-pastoral ecotone in the upper Yellow River valley as the study area, an ecological network was established using Graphab software based on the integral landscape heterogeneity analysis, in which the morphological spatial pattern analysis (MSPA) and structural equation model (SEM) were used to identify the ecological source regions and determine the resistance surface. The results showed that grazing and agricultural activities are the main reasons for the landscape complexity and heterogeneity. SEM also revealed the interactions between geographical conditions and landscape heterogeneity. The regression coefficients showed that the contribution of various factors on landscape heterogeneity were in order from strong to weak elevation, roads, settlements and slope. The influencing effects on landscape patterns were mainly reflected by the patch density, fractal dimension and landscape division indexes, with coefficients of −0.94, −0.91 and −0.88, respectively. The established ecological network shows that the overall planning of natural habitat and cultivated land will effectively improve the landscape quality. The presence of "stepping stone" patches in the central and eastern regions of the study area increases the landscape connectivity. In addition, the rational planning and utilization of high heterogeneity areas in the landscape are critical for maintaining the structure and function of the landscape. Findings from our study could provide a reference method for maintaining the landscape stability and sustainable development of heterogeneous agro-pastoral ecotones.

Ecological function evaluation and restoration strategy of rivers in urban built-up areas: a case study of the Dasha River in Shenzhen

With the rapid development of urbanization and national economy, the ecological function of rivers has been seriously threatened. In order to evaluate the present situation of ecological function of rivers in urban built-up areas and provide theoretical basis for subsequent river ecological restoration and sponge city planning, we carry out a case study of the Dasha River in Shenzhen city. We construct the ecological function evaluation index system at the reach scale for the Dasha River, in which 10 indicators and 14 indexes of four functions of hydrological support, water environment sustainment, habitat and biodiversity maintenance are evaluated by index evaluation method with aquatic organisms as the core. The index weight is calculated by the analytic hierarchy process method. The results show that the middle reach of the Dasha River is in class Ⅱ level, which is less disturbed by human activities and has relatively integral ecological functions. The upper and middle upper reaches are class Ⅲ areas and some ecological functions are threatened. The lower estuary section is class Ⅳ reach, which is seriously affected by human activities. Combing with the evaluation results of ecological function, we put forward the ecological restoration strategies for each reach, and suggest the daily management measures from the aspects of pollutant, biological species management, ecosystem regulation, and public education. This study provides basis and guidance for the evaluation and restoration of the ecological function and the sponge city construction in urban built-up areas.

Combining genotype, phenotype, and environmental data to delineate site-adjusted provenance strategies for ecological restoration.

Despite the importance of climate-adjusted provenancing to mitigate the effects of environmental change, climatic considerations alone are insufficient when restoring highly degraded sites. Here we propose a comprehensive landscape genomic approach to assist the restoration of moderately disturbed and highly degraded sites. To illustrate it we employ genomic data sets comprising thousands of single nucleotide polymorphisms from two plant species suitable for the restoration of iron-rich Amazonian Savannas. We first use a subset of neutral loci to assess genetic structure and determine the genetic neighbourhood size. We then identify genotype-phenotype-environment associations, map adaptive genetic variation, and predict adaptive genotypes for restoration sites. Whereas local provenances were found optimal to restore a moderately disturbed site, a mixture of genotypes seemed the most promising strategy to recover a highly degraded mining site. We discuss how our results can help define site-adjusted provenancing strategies, and argue that our methods can be more broadly applied to assist other restoration initiatives.

Naturalness Assessment of Forest Management Scenarios in Abies balsamea–Betula papyrifera Forests

Research Highlights: This research provides an application of a model assessing the naturalness of the forest ecosystem to demonstrate its capacity to assess either the deterioration or the rehabilitation of the ecosystem through different forest management scenarios. Background and Objectives: The model allows the assessment of the quality of ecosystems at the landscape level based on the condition of the forest and the proportion of different forest management practices to precisely characterize a given strategy. The present work aims to: (1) verify the capacity of the Naturalness Assessment Model to perform bi-directional assessments, allowing not only the evaluation of the deterioration of naturalness characteristics, but also its improvement related to enhanced ecological management or restoration strategies; (2) identify forest management strategies prone to improving ecosystem quality; (3) analyze the model’s capacity to summarize the effect of different practices along a single alteration gradient. Materials and Methods: The Naturalness Assessment Model was adapted to the Abies balsamea–Betula papyrifera forest of Quebec (Canada), and a naturalness assessment of two sectors with different historical management strategies was performed. Fictive forest management scenarios were evaluated using different mixes of forestry practices. The sensitivity of the reference data set used for the naturalness assessment has been evaluated by comparing the results using data from old management plans with those based on Quebec’s reference state registry. Results: The model makes it possible to identify forest management strategies capable of improving ecosystem quality compared to the current situation. The model’s most sensitive variables are regeneration process, dead wood, closed forest and cover type. Conclusions: In the Abies balsamea–Betula papyrifera forest, scenarios with enhanced protection and inclusion of irregular shelterwood cuttings could play an important role in improving ecosystem quality. Conversely, scenarios with short rotation (50 years) could lead to further degradation of the ecosystem quality.

Water use characteristics of the common tree species in different plantation types in the Loess Plateau of China

Knowledge concerning the water use characteristics of revegetated species has profound implications for understanding soil–plant interaction mechanisms and guiding ecological restoration strategies in water-limited ecosystems. Although afforestation is an important way to improve ecosystem functions and services in degraded ecosystems, there is limited understanding about the water use characteristics of dominant species within and between different types of plantations. We investigated plant water use characteristics in three representative types of plantations on the Chinese Loess Plateau: mixed plantation consisting of three deciduous tree species Robinia pseudoacacia, Armeniaca sibirica and Ailanthus altissima (Mspa), pure R. pseudoacacia plantation (Pp) and pure A. sibirica plantation (Ps). We measured the leaf δ13C of the dominant species within each plantation type and the δ2H and δ18O of xylem and soil water within 400 cm of the soil surface. The results showed that three main species in the mixed plantation exhibited significant difference (p < 0.05) in proportional contributions of water sources, suggesting that the plants had water source segregation. A. sibirica in the mixed plantation utilized more proportional shallow soil water than that in the pure plantation and correspondingly lessened deep soil water depletion. However, no significant difference was found in the water uptake proportions of R. pseudoacacia between the different plantation types. The leaf δ13C values of the plant species in the mixed plantation were significantly higher than those in the pure plantations. The leaf δ13C values of R. pseudoacacia under different plantation were positively associated with SWCs, but this relationship was not observed in A. sibirica. These results indicate that plantation type affected plant water use characteristics with species-specific responses to plantation type and different water source competition effects between interspecific versus intraspecific competition.

Investigation of the relationship between precipitation extremes and sediment discharge production under extensive land cover change in the Chinese Loess Plateau

To quantify the effects of rainfall and catchment characteristics on sediment yield is of essential importance for sustainable land management. Precipitation extremes are the external cause of the majority of serious soil erosion and suspended sediment yield (SSY) events in the Chinese Loess Plateau (CLP), which has undergone extensive land use/cover change (LUCC). The investigation of the linkage between climate variables and SSY production is crucial to the precise implementation of ecological restoration strategies, thereby reducing soil loss in the CLP. In this study, a partial least squares regression (PLSR) approach is used to investigate this issue using 1961–2015 data from 16 main catchments in the CLP. This period includes the reference period (1961–1979, Period-I), integrated soil conservation project period (1980–1999, Period-II), and the “Grain for Green” program period (2000–2015, Period-III). The results indicate that the dominant climate factors driving SSY are precipitation extremes including maximum precipitation events, heavy precipitation (daily precipitation ≥25 mm), consecutive wet days, erosive precipitation (daily precipitation ≥12 mm), and annual total precipitation. The effects of the precipitation extremes on sediment yield generation are stronger in drier catchments. The influence of the precipitation extremes on sediment generation can be strengthened by cultivation and weakened by revegetation (especially reforestation). The climate-driven sediment yield decreased by 951 t·km−2·yr−1 during Period-II and 505 t·km−2·yr−1 during Period-III in comparison with Period-I. The dominant cause of the sediment yield reduction was LUCC, with the contribution increasing from 73% in Period-II to 92% in Period-III. This study provides a greater understanding of the effects of climate variation and LUCC on sediment yield, and is beneficial for better catchment management.

Urban flood resilience, a discursive-institutional analysis of planning practices in the Metropolitan City of Milan

Flood risk is increasing all over the globe due to urbanization and the effects of climate change. Water managers and urban planners try to cope with flood risk by enhancing urban flood resilience. Three main discourses of resilience are engineering, ecological, and socio-ecological resilience. Whereas the discourse of engineering resilience emphasizes the use of flood protection infrastructures, the discourses of ecological and socio-ecological resilience advocate river restoration and spatial strategies to reduce flood risk. In this paper, we investigate which resilience discourse is dominant in the Lambro river basin (Metropolitan City of Milan), and how this discourse has been translated into institutions (rules-in-use) and outcomes, such as flood protection infrastructures or building regulations. Our discursive-institutional analysis is informed by the (politicized) Institutional Analysis and Development (IAD) framework, which highlights the role of discursive, institutional, and contextual factors in explaining the outcomes of strategic interactions within action arenas. It is shown that whereas bottom-up initiatives try to foster socio-ecological resilience, the engineering resilience discourse still dominates within the Lambro river basin because national policies and funds are geared towards hard infrastructure measures.

Identification of climate variables dominating streamflow generation and quantification of streamflow decline in the Loess Plateau, China

Precipitation-extremes-driven floods, which compose an important proportion of streamflow but cause severe adverse impacts in the Loess Plateau of China, urged the progressive implementation of ecological restoration (ER) strategies in the Loess Plateau (LP) of China. Knowledge of the linkage between climate variables (especially precipitation extremes) and streamflow generation become more essential for advanced catchment management as ER and climate variability have resulted in reduced streamflow and freshwater stress. Here, a partial least squares regression (PLSR) approach was used to investigate this issue at 16 main catchments of the LP over a reference period (1961–1979). Then, we quantified streamflow decline during the “Integrated Soil and Water Conservation” (1980–1999) and the “Grain for Grain” (2000–2015) strategies by PLSR modeling. We found that the dominant climatic variables controlling annual streamflow include heavy precipitation amount and heavy precipitation days, maximum precipitation event amount, number of consecutive wet days, annual total precipitation (daily precipitation ≥1 mm), and effective precipitation amount (daily precipitation ≥5 mm). Further, the effect of precipitation extremes on streamflow generation is stronger in drier catchments. The impacts of precipitation extremes on streamflow generation can be strengthened by agricultural cultivation and weakened by revegetation (especially reforestation). Overall, we found that climate-driven annual streamflow decreased by 7.5 mm during 1980–1999 and by 5.6 mm during 2000–2015, in comparison to 1961–1979. The dominant cause of streamflow reduction was ER, with the contribution increasing from 59% in 1980–1999 to 82% in 2000–2015. The PLSR approach enables the identification of linkages between climate variables and streamflow generation, and the prediction of climate-driven streamflow. This study yields a greater understanding of the influences of climate variability and ER on streamflow change, and is helpful to identify hydroclimatological trends and projections.

Estimation of potential ecological carrying capacity in China

It is urgent to explore the potential ecological carrying capacity (PECC) of regions where the study of ecological carrying capacity (ECC) is difficult to meet the real-world requirements of building an ecological civilization. In this study, classification and regression tree models were applied for estimating potential normalized difference vegetation index (PNDVI) based on climate variables and training data of actual NDVI. Then, potential net primary productivity (PNPP) was simulated by using Carnegie-Ames-Stanford Approach (CASA) model and PNDVI. On this basis, PECC of 31 provinces in China was estimated using the improved ecological footprint model and compared results with actual condition in 2015. The results showed the following: per capita PECC presented immense spatial differences, with high values in the northwest and low values in the southeast. The total PECCs of eight provinces were far greater than their actual total ECCs in 2015. Human activities in five provinces had the greatest negative impact on the ecological environment and the greatest pressure on ecological restoration. This study provided a new way to estimate the spatial distribution of potential ecological carrying capacity and found that spatial simulations of PNDVI, PNPP, and PECC can better quantify the difference between actual and potential ecological conditions under external pressures and can provide a trustworthy scientific basis for formulating differentiated ecological restoration strategies.

Passive and active ecological restoration strategies for abandoned farmland leads to shifts in potential soil nitrogen loss by denitrification and soil denitrifying microbes

AbstractEcological restorations of abandoned farmland have been performed in degraded ecosystems with the goal of increasing ecosystem sustainability. The environmental benefits of ecological restoration can at least be partially neutralized by enhanced nitrogen (N) loss and potential nitrous oxide (N2O) emissions via denitrification. However, few studies have focussed on comparative analysis of the contributions of ecological restoration strategies to soil denitrifying microbes, particularly in arid and semiarid degraded ecosystems, where N is often the limiting nutrient. In this study, artificial afforestation (artificial forest sites) and natural revegetation (grassland sites) of abandoned farmland have an enhanced effect on reducing potential denitrification rates (PDR) compared with farmland sites and orchard sites, leading to lower N losses and potential N2O emissions. Combined analyses indicated that the greatest differences in microbial abundance, species richness, and diversity were observed among different ecological restoration strategies. The abundance, richness, and diversities of denitrifying microbes (nirS, nirK, and nosZ genes) were decreased by natural revegetation and artificial afforestation, leading to attenuated denitrifying activity responsible for the reduced PDR. Notably, the abundance and diversity of denitrifying microbes were dominant variables that explained the changes in PDR (up to 0.96). Overall, our results contribute to a better understanding of the feedback of denitrifying microorganisms to ecological restoration strategies and how these microorganisms collaboratively contribute to N loss and potential N2O emissions in arid and semiarid degraded ecosystems.

Foraging behavior of the Eurasian Three-toed Woodpecker (Picoides tridactylus) and its implications for ecological restoration and sustainable boreal forest management

Several studies have shown that the Three-toed Woodpecker (Picoides tridactylus) is strongly favored by large-scale disturbances, including forest fires. However, natural disturbances have largely disappeared from European boreal forests because of modern forestry practices and fire suppression. We currently lack knowledge on the foraging activity and resource use of the Eurasian Three-toed Woodpecker, especially in burned forests, and this restricts our ability to develop strategies for sustainable forest management and ecological restoration aiming at improving the situation of this woodpecker and associated species. In order to fill this knowledge gap, we studied the characteristics of selected foraging substrates and the foraging behavior of the Three-toed Woodpecker during the breeding season in unburned forests and forests that have been subjected to prescribed burning. We used instantaneous sampling duringtwo consecutive springs (2016-2017), where we observed the woodpeckers’ foraging behavior during a total of 977 minutes in burned forest and 962 minutes in unburned forests. The preferred foraging substrate for Three-toed Woodpeckers in both burned and unburned forests can be characterized as freshly dead trees with a DBH > 15 cm. However, data on time spent foraging on different substrates suggest that also substrates in the 5-15 DBH range and living trees are important. Additionally, prescribed burnings led to less pronounced selection of tree species, which suggest that fire may reduce differences in abundance of saproxylic insect prey between tree species. This information on substrate selection and foraging time provide complementary knowledge and thus should be used simultaneously when management strategies for improved woodpecker habitat are developed. Our results suggest that both prescribed burning and protecting forests with high density and diversity of dead wood provides habitat opportunities for Three-toed Woodpeckers and using both in management may maximize conservation outcome

Distribution and environmental characteristics of the spawning grounds of Scomberomorus niphonius in the coastal waters of Yellow Sea, China

Japanese Spanish mackerel (Scomberomorus niphonius) is one of the main economic fish species in the Yellow Sea. To understand its spawning habitat and population dynamics in the early stage, we examined the distribution and environmental characteristics of spawning ground of Japanese Spanish mackerel using their egg survey data collecting in 2015 (late May) and 2017 (late May) in the coastal waters of Yellow Sea. The generalized additive model (GAM) with the Tweedie distribution was used to analyze the distribution and environmental characteristics of its spawning ground. The results showed that egg distribution was significantly related to the location (i.e., latitude and longitude), water depth, and sea surface temperature (SST), but not related to sea surface salinity (SSS). The optimal range of depth and SST were 15-30 m and 16-20 ℃, respectively. The mackerel spawning ground mainly distributed in the region Shidao fishing ground (area near 36°30' N,121°48' E) and Haizhou Bay (33°30'-36° N,119°30'-121°30' E). There were some clear inter-annual differences in the distribution of mackerel spawning ground, with the spawning ground tending to northward in the year with higher sea temperature. Therefore, it is necessary to manage and protect the above spawning ground (especially the Haizhou Bay), establishing the corresponding ecological protection and restoration strategy, to realize sustainable exploitation of mackerel fisheries resources in the Yellow Sea.

Study on soil ecological environment restoration strategy of abandoned mining area

Mine ecological restoration is the current necessary step in the process of resources exploitation, so for the study of the mining area ecological restoration, ecological restoration of phosphate rock mountain lands after the ecological benefit evaluation, using the analytic hierarchy process (AHP) method and frequency analysis method to select the phosphate rock mountain land ecological benefit evaluation index, evaluated by calculation results shows that the calculation by using the underground runoff water conservation quantity is 11832.036 m3/a with water and soil conservation quantity of 14976.4 m3/a. If the area of vegetation broad-leaved forest that can be formed after ecological restoration in the mining area is 50.0 h m2 and the area of coniferous forest is 10.0 h m2, the blocking dust capacity can be obtained to be 832.11 t/a. The indirect economic value of water conservation, water and soil conservation, and environmental purification calculated by shadow engineering method is respectively 8791.6 yuan/a, 166.6 yuan/a, and 141458.7 yuan/a, and the environmental value of water purification is 13121.784 yuan/a, and the overall indirect economic benefit value is 1.64 105 yuan/a. The practice shows that the research index of ecological restoration strategy is more comprehensive and scientific, which provides another method for ecological environment restoration strategy of mining areas in China and promotes the sustainable development of ecological environment.

A watershed scale assessment of phosphorus remediation strategies for achieving water quality restoration targets in the western Everglades

Watershed scale models have become important tools to assess the effectiveness of regional and farm level remediation strategies for ecological restoration. The Everglades is an ecologically unique and complex system posing numerous challenges to water managers in South Florida. The Feeder Canal Basin (FCB) in Hendry County, Florida, drains 277 km2 of land into the central Everglades. During 2008–2017, the average annual total phosphorus (TP) concentration at the FCB outflow was approximately 89 μg/L, almost an order of magnitude higher than the restoration target for the Everglades marshes. This study aimed at evaluating remediation strategies - Best Management Practices (BMPs) and Stormwater Treatment Areas (STAs) to achieve TP targets for ecosystem restoration using an integrated modeling framework with a top-down approach. The baseline regime was modeled using the Watershed Assessment Model with multi-gage calibration (2000−2003) and validation (2004–2010). With the model performing satisfactory to very good for all gage locations, results indicated that row crops, groves & orchards, and improved pastures were largely responsible for TP concentrations and/or loads. BMP scenario results showed that TP loads could be reduced by 8% to 24% at the FCB outlet under minimal or very aggressive BMPs, respectively, indicating the need for additional water quality improvement projects to meet restoration targets. A preliminary design of two STAs, using the Dynamic Model for Stormwater Treatment Areas, estimated that a total of 52 km2 and 11.3 km2 of STAs will be required to achieve the TP concentration targets. The analysis framework employed in this study can be replicated in other watersheds to provide a holistic picture of remediation measures required to achieve water quality targets.

Formulating an Elasticity Approach to Quantify the Effects of Climate Variability and Ecological Restoration on Sediment Discharge Change in the Loess Plateau, China

AbstractSuspended sediment yields (SSY) respond strongly to ecological restoration (ER) efforts, and significant improvements in SSY control have been achieved in the Loess Plateau of China. However, it remains challenging to quantify the net impacts of ER on SSY. Here, we formulate the notion of elasticity of sediment discharge, by associating SSY change to climate variability and ER over the period 1950s to 2014. All ten of the subcatchments studied experienced significant decreases in annual SSY, streamflow, and suspended sediment concentration. Our results strongly support the hypothesis that changes to both streamflow volumes and to the suspended sediment concentration versus water discharge (C‐Q) relationships result in reduced SSY, so that streamflow is reduced but runs clearer. We find that two of the ER strategies resulted in weaker relative impacts of climate variability, largely by reducing streamflow (by 55% to 75%). Meanwhile, ER predominantly decreased SSY (by 63% to 81%). Regarding ER practices, (i) the predominant measure acting to reduce SSY changed, over time, from engineering to reforestation; (ii) check dams preferentially act to regulate the C‐Q relationships, whereas reforestation preferentially acts to moderate streamflow. Overall, our results suggest that a combination of engineering and vegetation measures is critical to achieving high‐efficiency ER. While change to the ER strategy increased the efficiency of streamflow for SSY control, the lost water discharge per unit SSY reduction increased from 5.2 to 6.4 m3·t−1. Conflicting demands for water necessitate that further ER should target precision management by revegetation of targeted areas in the Loess Plateau.

Regional water-energy cycle response to land use/cover change in the agro-pastoral ecotone, Northwest China

A better understanding of responses of the regional water-energy cycle to land use/cover change (LUCC) is important for ecological restoration in the agro-pastoral ecotone, Northwest China (APENWC). In this study, we examined the responses to various types of LUCC in the APENWC during the implementation of the Grain-for-Green project between 1993 and 2010 using the weather research and forecasting (WRF) model. The performance of the WRF model was validated by multiple types of observations. Results show that the WRF can accurately simulate regional water and energy processes in the APENWC, and that the water-energy cycles in the region are strongly affected by vegetation dynamics. During the period of 1993 and 2010, the most obviously increased land cover types were the grassland and barren land, and the decreased land cover types were shrublands and croplands in the study region. A significantly negative correlation (R2 = 0.78) between land surface temperature (LST) and albedo was found, associated with a 0.5 °C reduction in the annual mean surface temperature in the APENWC between 1993 and 2010. Negative correlations between changes in evapotranspiration (ET) and albedo during the period in all seasons were also detected, except summer, when the correlation was positive (R2 = 0.49). This is attributed to transpiration from plants being the main contributor to ET in summer and, hence total ET. The changes resulted in an increase of ET by 19.79 mm in summer, and decreases of ET by 1.15 mm, 13.22 mm, and 0.96 mm, respectively, in spring, fall, and winter. The LUCC also resulted in reductions in precipitation (of 2.3, 7.31, and 7.8 mm in spring, summer, and fall, respectively) by altering local ET and vapor flux cycles in the APENWC, and the study region contributed additional moisture from the local ET into the north of the region. The findings show that the grassland expansion reduces mean land surface temperature, which will delay germination of seeds and initiation of vegetation growth in spring. Increases in seasonal ET and reductions in seasonal precipitation will lead to soil drying, exacerbating risks of summer drought in the APENWC. The findings provide important information in facilitating formulation of effective strategies for sustainable development and ecological restoration in the APENWC and similar regions.

Changes in soil properties rather than functional gene abundance control carbon and nitrogen mineralization rates during long-term natural revegetation

Agricultural abandonment has been taken as one of the most widely used strategies for ecological restoration. Abandoned croplands expanded worldwide since the middle of the twentieth century and will increase considerably in the future. Whether agricultural abandonment alters the abundances of soil carbon (C) and nitrogen (N) mineralization genes, and whether these functional genes are linked to alterations in C and N mineralization rates remain unknown. We took advantage of a well-established chronosequence of nature restoration sites on abandoned croplands which represent a century of vegetation succession in China’s Qinling Mountains, to determine soil C and N mineralization rates, and their relationships with vegetation succession, edaphic characteristics, soil microbial communities, and functional genes based on GeoChip 5.0. We found that soil C and N mineralization rates, microbial biomass and composition, and the number and abundances of functional genes were significantly affected by vegetation succession following agricultural abandonment. Soil C and N mineralization rates increased by sixfold and threefold, respectively, along the cropland to forest successional gradient. The NO3-N, NH4-N and soil available phosphorus (P) concentrations were important factors associated with the C and N mineralization genes. The shifts in edaphic environments (i.e., soil moisture, cation exchange capacity, and C/P ratio), vegetation-derived substrates (i.e., soil organic C and N), and soil microbial composition (i.e., Fungi/Bacteria ratio, amounts of Gram-negative bacteria, Actinomycetes, and arbuscular mycorrhizal fungi), rather than the abundances of functional genes involved in mineralization processes, controlled soil C and N mineralization rates along the long-term vegetation successional gradient. Abandoning cropland for natural succession could facilitate the recuperation of soil C and N processes and alter soil microbial composition and functional genes. The abundances of microbial functional genes are less important than previously expected in regulating soil C and N mineralization rates.

Ecological restoration for biodiversity conservation improves habitat quality for an insectivorous passerine in boreal forest

It is increasingly recognized that successful biodiversity conservation will necessitate active ecological restoration measures. In boreal forests, emulating natural disturbances is commonly used as a restoration tool for improving habitat quality for a range of sensitive species. We assessed the consequences of prescribed burning and artificial gap creation on the demographic parameters of an insectivorous bird, the pied flycatcher (Ficedula hypoleuca). This to improve our ability to develop strategies for successful ecological restoration aiming at improving the conservation status of boreal forest birds. Pied flycatchers reproduced equally well in nature reserves, forests subjected to ecological restoration and untreated control stands. Nestling body weight was found to be higher in stands restored through prescribed burning. Considering that nestling condition at the time of fledging is known to be positively related to survival rates after fledging, our results suggest a positive effect of prescribed burning on population dynamics and on local habitat quality. Our findings should encourage forest managers to actively use prescribed burning as a management tool in boreal forests to complement other conservation measures. However, one should be careful with generalizing these results to other bird species as they only are directly applicable to pied flycatchers. Still, they may potentially apply also to other insectivorous bird species with similar habitat requirements. In addition, it should be stressed that to maintain diverse boreal forest bird assemblages, heterogeneous landscapes are needed including both burned and unburned forest of different successional stages.