Implications For Ecosystem Restoration Research Articles

A comprehensive framework for vegetation succession

AbstractSuccession is defined as a directional change in species populations, the community, and the ecosystem at a site following a disturbance. Succession is a fundamental concept in ecology as it links different disciplines. An improved understanding of succession is urgently needed in the Anthropocene to predict the widespread effects of global change on succession and ecosystem recovery, but a comprehensive successional framework (CSF) is lacking. A CSF is needed to synthesize results, draw generalizations, advance successional theory, and make improved decisions for ecosystem restoration. We first show that succession is an integral part of socio‐ecological system dynamics and that it is driven by social and ecological factors operating at different spatial scales, ranging from the patch to the globe. We then present a CSF at the local scale (patch and landscape) at which succession takes place and explain the underlying successional processes and mechanisms operating at that scale. The CSF reflects the increasingly broader perspective on succession and includes recent theoretical advances by not only focusing on species replacement but also on ecosystem development, considering succession as part of a socio‐ecological system, and taking the effect of past and current land use, the landscape context, biotic interactions, and feedback loops into account. We discuss how the CSF can be used to integrate and synthesize successional studies, and its implications for ecosystem restoration.

Spatio-Temporal Variation and Climatic Driving Factors of Vegetation Coverage in the Yellow River Basin from 2001 to 2020 Based on kNDVI

The Yellow River Basin (YRB) is a fundamental ecological barrier in China and is one of the regions where the ecological environment is relatively fragile. Studying the spatio-temporal variations in vegetation coverage in the YRB and their driving factors through a long-time-series vegetation dataset is of great significance to eco-environmental construction and sustainable development in the YRB. In this study, we sought to characterize the spatio-temporal variation in vegetation coverage and its climatic driving factors in the YRB from 2001 to 2020 by constructing a new kernel normalized difference vegetation index (kNDVI) dataset based on MOD13 A1 V6 data from the Google Earth Engine (GEE) platform. Using Theil–Sen median trend analysis, the Mann–Kendall test, and the Hurst exponent, we investigated the spatio-temporal variation characteristics and future development trends of the vegetation coverage. The climatic driving factors of vegetation coverage in the YRB were obtained via partial correlation analysis and complex correlation analysis of the associations between kNDVI and both temperature and precipitation. The results reveal the following: The spatial distribution pattern of kNDVI in the YRB showed that vegetation coverage was high in the southeast and low in the northwest. Vegetation coverage fluctuated from 2001 to 2020, with a main significant trend of increasing growth at a rate of 0.0995/5a. The response of vegetation to climatic factors was strong in the YRB, with a stronger response to precipitation than to temperature. Additionally, the main driving factors of vegetation coverage in the YRB were found to be non-climatic factors, which were mainly distributed in Henan, southern Shaanxi, Shanxi, western Inner Mongolia, Ningxia, and eastern Gansu. The areas driven by climatic factors were mainly distributed in northern Shaanxi, Shandong, Qinghai, western Gansu, northeastern Inner Mongolia, and Sichuan. Our findings have implications for ecosystem restoration and sustainable development in the YRB.

Difference in hydraulic resistance between planted forest and naturally regenerated forest and its implications for ecosystem restoration in subtropical karst landscapes

Drought-induced plant hydraulic failure is expected to increase under climate change, and this negatively affects reforestation under the fragile karst environment in subtropical China. Compared with naturally regenerated forests, planted forests can rapidly increase vegetation coverage and have considerable economic benefits; however, their degree of resistance to drought-induced hydraulic failure is still unclear. Our study aimed to fill this knowledge gap by examining the differences in hydraulic characteristics between planted forests and naturally regenerated forests. Sample sites for both types of forest were selected in the humid subtropical karst region, and the hydraulic safety margin, stomatal conductance, and species-specific growing season length were measured for statistical analyses. The planted forest had a narrower hydraulic safety margin and presented a greater vulnerability to hydraulic failure than the naturally regenerated forest; however, it can bud later and abscise leaves early to avoid hydraulic failure. This study is the first to provide evidence of coordination between plant safety margin and species-specific growing season length in fragile karst ecosystems. To increase vegetation coverage and reduce soil erosion, the combination of both forest types could be an optimal ecosystem restoration strategy. Our study provides critical information for ecosystem restoration and management in subtropical karst areas.

Clear-Cuts Are Not Clean Slates: Residual Vegetation Impediments to Savanna Restoration

ABSTRACT In response to widespread losses of savanna ecosystems worldwide, many restoration efforts are underway. For savannas degraded by fire suppression and hardwood invasion, a first step towards restoration typically involves removal of unwanted trees and shrubs, but after invasive nonnative woody plants are top-killed, savanna restoration is often impeded by their resprouts. To evaluate patterns of vegetative recovery following clear-cuts and to explore their implications for ecosystem restoration, we determined the origins of the vegetation that develops after a clear-cut in hardwood-invaded sites being restored to pine savanna in Florida. We excavated stumps and other sprout sources, characterized the soil seed bank, and estimated seed production by early-to-mature species during the first growing season after treatment. In twenty 100-m2 plots, there was approximately one source of woody plant sprouts per square meter. Root sprouts were more abundant than sprouted stumps, and most of the stumps t...

Occurrence of Shortleaf × Loblolly Pine Hybrids in Shortleaf Pine Orchards: Implications for Ecosystem Restoration

Occurrence of Shortleaf × Loblolly Pine Hybrids in Shortleaf Pine Orchards: Implications for Ecosystem Restoration

Strong inference from transect sign surveys: combining spatial autocorrelation and misclassification occupancy models to quantify the detectability of a recovering carnivore

Monitoring of species using surveys of ambiguous signs and assuming 100% detectability produces potentially biased occupancy estimates. Novel analytical tools have been developed that correct for bias arising from imperfect detectability, species misidentification and spatial autocorrelation between detection survey replicates that can affect transect surveys. To date they have been applied individually, but their combined value is unclear.The recovery of carnivores such as the European pine marten Martes martes potentially has far reaching, but largely unknown, implications for ecosystem restoration. Analysis of the species' distribution has as yet been crude and hence unsuited for informing management. We aimed to assess the validity of standard scat surveys to provide recommendations to increase inference from future surveys.We employed spatially replicated scat surveys along forest paths in NE Scotland, genetic verification of scat provenance and occupancy modelling techniques to quantify pine marten detectability and variation therein. Detectability for 1 km and 1.5 km transects, comparable to standard protocols, was estimated to be 0.35 and 0.58 respectively, highlighting the importance of accounting for imperfect detectability. Detection probabilities decreased with vegetation cover and increased with path width. Models accounting for spatial autocorrelation between adjacent transect segments suggested that segments of ≥ 400 m could be analysed as spatial replicates with negligible bias. As is the norm, not all scats yielded DNA to genetically verify they were produced by pine marten. This was accounted for through the use of ‘miss‐classification occupancy models’ which allowed the use of unverified scats, increasing detection probabilities while accounting for the probability of unverified scats being false positive detections.This study exemplifies that robust inference on species occupancy is achievable through careful consideration of sampling design and the application of readily available analytical techniques. Adopting best‐practice need not increase monitoring costs and can even increase cost‐efficiency.

Patterns of vegetation composition and diversity in pine-dominated ecosystems of the Outer Coastal Plain of North Carolina: Implications for ecosystem restoration

Terrestrial ecosystems of the Atlantic coastal plain have experienced considerable change over the past two centuries, largely due to agricultural activities and fire suppression and exclusion. Many areas that were once dominated by open longleaf pine (Pinus palustris) woodlands now support closed canopy stands of loblolly pine (Pinus taeda) with a dense midstory of broadleaved shrubs and trees. In recent years, efforts to restore the herbaceous plant communities typically found in fire-maintained longleaf pine woodlands have focused on the use of midstory thinning to produce savanna-like conditions and to facilitate the restoration of historical fire regimes through prescribed burning. Previous efforts to restore longleaf pine stands have focused on the potential of fire-suppressed longleaf pine woodlands, which have been met with some success. However, it is unclear what the potential is for loblolly pine stands to act as a ’surrogate’ environment for the restoration of the often species-rich herbaceous layer of longleaf pine woodlands. To assess the effectiveness of longleaf pine restoration treatments in existing loblolly pine stands, we analyzed the drivers of plant community composition in loblolly pine stands with mechanical midstory removal treatments, untreated loblolly pine stands, longleaf pine stands, and pond pine dominated high-pocosin systems. We sampled 75 plots, from which more than 200 individual plant taxa were identified, with species richness (number of species per 0.1ha) ranging from 9 in pond pine pocosins to 118 in longleaf pine woodlands. Plant species richness and composition varied in response to soil properties, with the first NMS ordination axis correlated with soil properties related to soil moisture and organic matter content (SOM), and the second NMS ordination axis correlated to the concentration of certain soil nutrients (P, Ca), the variability of which may be due, in part, to historic fertilizer applications. While stand types were largely distinct from each other in their vegetation composition, there was nevertheless some compositional overlap among some longleaf and loblolly pine stands. Areas of compositional overlap appear to have somewhat similar soil properties, whereby the soils found in overlapping loblolly pine stands were closer to those found in longleaf pine stands (i.e. low SOM content). Thus, an assessment of the soil properties of loblolly pine stands may allow for an identification of candidate sites for which longleaf pine restoration treatments may be most effective.

Causes of reintroduction failure of the brown treecreeper: Implications for ecosystem restoration

Reintroductions are conducted to re-establish a self-sustaining population of a species and contribute to ecosystem restoration. The brown treecreeper (Climacteris picumnus) reintroduction into two nature reserves in the Australian Capital Territory in south-eastern Australia failed to meet its predetermined criteria for success. This occurred despite prior habitat restoration within the reserves where reintroduction occurred. Low survival of reintroduced brown treecreepers, particularly due to predation by native predators, has previously been highlighted as a key factor in the failure of the programme. We compared bird behaviour and habitat characteristics between the reintroduction reserves and the sites where brown treecreepers were sourced (which support stable brown treecreeper populations). We did not identify an indication of significantly higher predation pressure in the reintroduction reserves in comparison with the source sites. However, our results revealed that reintroduced individuals may be more vulnerable to predation because of an increased flight time to reach a refuge area. This was a result of a significantly lower number of refuge areas in logs and trees and a higher number of shrubs (which may obstruct escape paths and hinder detection of predators) in the reintroduction reserves compared with the source sites. We identified a lower ground foraging habitat quality in the reintroduction reserves because of lower numbers of ant mounds and lower areas of forageable ground. However, brown treecreepers were able to disperse extensively throughout the reserves and settle in areas with generally higher-quality foraging habitat. Therefore, the negative effect of low ground foraging habitat quality would have been most pronounced immediately after release. This study emphasizes the inherent complexities of species reintroductions and ecosystem restoration. Despite experimental restoration activities within the reintroduction reserves, there were still deficiencies in habitat quality. We emphasize that further habitat restoration is required within these reserves to achieve more complete restoration.

Fish Assemblages in the Degraded Mangrove Ecosystems of the Coastal Zone, Benin, West Africa: Implications for Ecosystem Restoration and Resources Conservation

Mangrove forests are unique habitats in their function as potential food source and nurseries, and support an important fisheries resource. In the Benin coastal zone, the mangrove fishes have been surveyed to investigate fish species diversity, community structures and ecosystem degradation impacts in order to protect and to improve the mangrove fish resources. Results from wet, high-water and dry season samplings revealed that the two dominant mangrove species, Rizophora racemosa and Avicennia africana, are being intensively degraded for domestic use such as firewood and house building. Fifty one (51) fish species belonging to 25 families were recorded with Eleotridae (7 species), Cichlidae (5 species), and Mugilidae (5 species), the most speciose families. Dominant trophic guilds were detritivores (54.57%) and planktinovores/microcarnivores (30.41%). Six (6) species, Sarotherodon melanotheron, Dormitator lebretonis, Gerres melanopterus, Hemichromis fasciatus, Ethmalosa fimbriata, and Aplocheilichthys spilauchen, dominated the samples and accounted for about 80.27%. Sarotherodon melanotheron constituted the major dominant species and accounted numerically for about 29% of the total catches and 46.7% of the total biomass. The Margalef index of species richness ranged between 2.42 and 4.43, the Shannon-Weaver index of species diversity between 1.39 and 2.27, and the evenness between 0.50 and 0.62. Lower indices were observed for the highly degraded and the moderately degraded sites whereas higher indices were recorded for the less degraded and the restored sites. Species richness, species diversity and dominant species abundance were positively correlated with depth and transparency and negatively correlated with temperature. Multi-species fisheries dominate the coastal zone with Sarotherodon melanotheron, Dormitator lebretonis, Gerres melanopterus, Ethmalosa fimbriata, Liza falcipinus, Mugil sp. and Chrysichthys nigrodigitatus, the major species in the commercial catches. In addition to the mangrove destruction, the hydro electrical dam have greatly modified the Mono River flooding regime, water quality and the fish composition of the Benin coastal lagoon system. An integrated approach of the mangrove resource management/conservation, including intensive mangrove restoration, management of key fish species, freshwater prawns (Macrobrachiun sp.), peneids shrimps, mangrove oysters (Crassostrea sp.), and crabs (Callinectes sp., Cardiosoma sp.), and habitat protection is required for ecosystem recovery and sustainable exploitation.

Dissolved Organic Matter in the Florida Everglades: Implications for Ecosystem Restoration

Dissolved organic matter (DOM) in the Florida Everglades controls a number of environmental processes important for ecosystem function including the absorption of light, mineral dissolution/precipitation, transport of hydrophobic compounds (e.g., pesticides), and the transport and reactivity of metals, such as mercury. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the present transport of DOM from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. In part, the restoration plan calls for increasing water flow throughout the Everglades by removing some of the manmade barriers to flow in place today. The land- and water-use practices associated with the plan will likely result in changes in the quality, quantity, and reactivity of DOM throughout the greater Everglades ecosystem. The authors discuss the factors controlling DOM concentrations and chemistry, present distribution of DOM throughout the Everglades, the potential effects of DOM on key water-quality issues, and the potential utility of dissolved organic matter as an indicator of success of restoration efforts.

Effects of clearcutting on the tree species composition, structure, and diversity of a mixed broadleaf-Korean pine (Pinus koraiensis) forest on Changbai Mountain: implications for ecosystem restoration.

Large areas of primary mixed broadleaf-Korean pine forests on Changbai Mt., on the border between China and North Korean have been replaced by secondary forests through clearcuting since the 1950s. How clearcutting impacts the mixed forest ecosystem still remains unclear. We compared the tree species composition, structure, and diversity of a primary and a secondary forest that had suffered clearcutting, 30 yr. previously. Results showed that the mean basal area of trees (≥10 cm diameter at breast height (DBH)) was markedly lower in the secondary forest than in the primary forest, whereas the density of seedlings (＜2 cm DBH, ≥50 cm tall), saplings (2~9.9 cm DBH), and trees were all significantly higher in the former. Values for the species richness and both Simpson's and Shannon's diversity indices for seedlings and saplings were greater in the secondary forest than in the primary forest, but the values of these 3 indices for trees were significantly lower in the former. These results indicate that clearcutting altered the forest structure by significantly decreasing the basal area of trees and increasing the numbers of seedlings and saplings. It also altered the species composition with the secondary forest having more pioneer species than the primary forest. The secondary forest has higher species diversity and abundant climax species of seedlings and saplings, and this potentially favorable situation offers an opportunity to develop restoration plans.

The effect of topsoil removal in restored heathland on soil fauna, topsoil microstructure, and cellulose decomposition: implications for ecosystem restoration

Communities of soil macrofauna, oribatid mites, and nematodes as well as vegetation and soil chemistry were studied on twelve plots representing three replicates of the following treatments: agricultural meadow, heathland, and heathland restored either by partial or complete topsoil removal 15 years earlier. We also studied the effect of soil macrofauna on decomposition and the microstructure of the soil surface layer with litterbags in combination with the analysis of thin soil sections. The communities of soil macrofauna and oribatid mites significantly differed between agricultural meadows and heathlands. The partial and complete topsoil removal plots were more similar to heathlands with respect to macrofauna and to agricultural meadows with respect to oribatid mites. The density and diversity of soil macrofauna was higher in agricultural meadows than in heathlands; in particular, earthworms, litter transformers, root feeders, and microsaprophags were more abundant on meadows. Heathlands, in contrast, contained a much higher diversity of oribatid mites. The community structure of nematodes did not significantly differ among the treatments. Analysis of thin soil sections revealed a thick organic fermentation layer in heathlands, which was absent in agricultural meadows and only weakly developed in the topsoil removal plots. In agricultural meadows, litterbags and thin soil sections indicated that abundant macrofauna, including endogeic earthworms, were very effective in removing the litter from the soil surface and mixing it into the mineral soil. Possible effects of this soil mixing on restoration success are discussed.

Multiple‐scale soil moisture distribution and its implications for ecosystem restoration in an arid river valley, China

AbstractThe spatial distribution of soil moisture and its multiple‐scale correlations to other environmental factors were examined along the Upper Minjiang River valley, China, a landscape subject to severe land degradation of soil and water erosion but also under investigation for potential ecosystem restoration. Results showed that: (1) Soil moisture was highest in the headwaters, and lowest in the arid valley, while moderate values characterized outside the arid valley. The polynomial model of soil moisture distribution on slopes was concave in the lightly disturbed headwaters, convex in the highly damaged arid valley, while convex on south facing slopes and concave on north facing slopes in highly damaged areas in better environmental condition. (2) Soil moisture was correlated with environmental factors at different scales, where elevation and air humidity were only correlated at the sample plot scale, light intensity and wind speed were found to be significant at both slope and site scales and slope and sample plot scales; while slope angle was correlated at all the three scales. From this we conclude that it is possible to improve soil moisture conditions in the arid valley by lowering slope angle and adding low‐cost irrigation systems. (3) The practical threshold of soil moisture for growing meadows, shrubs, and forests were 11ċ800 per cent, 3ċ925 per cent, and 16ċ078 per cent respectively; the arid valley displayed soil‐moisture conditions unfavourable to forest growth. The planned reforestation project is not ecologically reasonable. Reducing human disturbance and revegetating with natural shrubs and meadows may produce more effective results. Copyright © 2004 John Wiley & Sons, Ltd.