Search

Copyright of Journal Architecture & Planning is the property of King Saud University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fire is a critical driver of giant sequoia (Sequoiadendron giganteum [Lindl.] Buchholz) regeneration. However, fire suppression combined with the effects of increased temperature and severe drought has resulted in fires of an intensity and size outside of the historical norm. As a result, recent mega‐fires have killed a significant portion of the world's sequoia population (13%–19%), and uncertainty surrounds whether severely affected groves will be able to recover naturally, potentially leading to a loss of grove area. To assess the likelihood of natural recovery, we collected spatially explicit data assessing mortality, crown condition, and regeneration within four giant sequoia groves that were severely impacted by the SQF‐ (2020) and KNP‐Complex (2021) wildfires within Sequoia and Kings Canyon National Parks. In total, we surveyed 5.9 ha for seedlings and assessed the crown condition of 1104 giant sequoias. To inform management, we used a statistical methodology that robustly quantifies the uncertainty in inherently "noisy" seedling data and takes advantage of readily available remote sensing metrics that would make our findings applicable to other recently burned groves. A loss of giant sequoia grove area would be a consequence of giant sequoia tree mortality followed by a failure of natural regeneration. We found that areas that experienced very high‐severity fire (above ~800 RdNBR) are at substantial risk for the loss of grove area, with tree mortality rapidly increasing and giant sequoia seedling density simultaneously decreasing with fire severity. Such high‐severity areas comprised 17.8, 142.0, 14.6, 1.6 ha and ~90%, ~14%, ~53%, and ~27% of Board Camp, Redwood Mountain, Suwanee, and New Oriole Lake groves, respectively. In all sampling areas, we found that seedling densities fell far below the average density measured after prescribed fires, where seedling numbers were almost certainly adequate to maintain giant sequoia populations and postfire conditions were more in keeping with historical norms. Importantly, spatial pattern is also important in assessing the risk of grove loss, and in two groves, Suwanee and New Oriole Lake, the high‐severity patches were not always contiguous, potentially making some areas more resilient to regeneration failure due to the proximity of surviving trees. [ABSTRACT FROM AUTHOR]

Establishing an artificial grassland is a common measure employed to restore heavily degraded alpine grasslands for regional sustainability. The Three-River Headwaters Region in China has significant areas of black-soil-type grassland which is typified by heavy degradation; nearly 35% of the grassland regions in the Three-River Headwaters Region has degraded into this type. There are different plant community types of black-soil-type grasslands, however, it is not clear which restoration measures should be adopted for different kinds of black-soil-type grasslands. Here, we investigate the plant community characteristics and soil physicochemical properties of artificial grasslands, two types of black-soiltype grasslands, and native undegraded grassland in the Three-River Headwaters Region, then analyzed the direct and indirect interactions between the plant and soil properties by partial least squares path models (PLS-PM). Our results revealed that establishing artificial grassland significantly increased aboveground biomass and plant community coverage, and also decreased plant species richness and diversity and soil water content, soil organic carbon and total nitrogen in the 0-10 cm soil layer as compared with black-soil-type grasslands. Plant community diversity had a positive effect on plant community productivity, soil nutrient, and soil water content in native undegraded grassland. These results suggest that more management interventions are needed after establishing an artificial grassland, such as reducing dominant species in two types of black-soil-type grasslands, water regulation in the A. frigida-dominated meadow, diversifying plant species (i.e., Gramineae and sedges), and fertilizer addition. [ABSTRACT FROM AUTHOR]

Many raised bogs in Central Europe are in an unfavorable state: drainage causes high emissions of carbon dioxide (CO2) and nitrous oxide (N2O), while rewetting may result in high methane (CH4) emissions. Also, the establishment of typical bog species is often hampered during restoration. Measures like topsoil removal (TSR) or introduction of target vegetation are known to improve restoration success in other systems, but experiences on bogs after long‐term agricultural use are scarce and their climate effects including carbon losses from TSR are unknown. In a field trial in north‐western Germany, consisting of seven plots (intensive grassland, IG, and six restoration approaches), we explored the effects of rewetting, TSR and Sphagnum introduction on greenhouse gas (GHG) emissions. We measured GHG fluxes to obtain two‐year GHG budgets and applied a radiative forcing model to assess the time‐dependent climate effects. Existing uncertainty of decomposition processes in the translocated topsoil has been incorporated by different topsoil accounting scenarios. According to our data, rewetting alone reduced CO2 emissions by approximately 75% compared to IG, but substantially increased CH4 emissions. After TSR and rewetting, on‐site CO2 emissions were close to zero or, with Sphagnum introduction, net negative while CH4 emissions remained very low. The climatic warming effect of TSR including C export becomes less climate warming than rewetting nutrient‐rich peatlands after a few decades. For raised bog restoration, we therefore recommend a TSR sufficient to achieve nutrient‐poor and acidic conditions needed for rapid Sphagnum establishment. [ABSTRACT FROM AUTHOR]

Forests in eastern North America are experiencing high densities of white-tailed deer (Odocoileus virginianus) and encroachment by invasive plants, both of which threaten native biodiversity. We review the literature on deer and invasive plant impacts focusing on studies that simultaneously evaluate the consequences of both. Deer have more frequent and more consistently negative effects than invasive plants. Widespread deer impacts now threaten many native plant species through much of their range. In contrast, invasive plant effects currently remain more localized and/or of smaller extent within forests. Deer impacts are also cumulative, hitting preferred plant species especially hard as they decline in density. This generates difficult-to-reverse legacy effects. Invasive plant effects, in contrast, tend to be more diffuse and may be more readily reversed. High deer populations also shift physical and chemical conditions in soils promoting "invasion cascades" involving non-native earthworms and certain introduced plants. Removing invasive plants without reducing deer populations can increase deer impacts on native species. Management should be integrated to address both deer and invasive plants. To safeguard and restore native biota when resources are limited, however, it may be most effective for managers to first reduce deer populations before investing in efforts to reduce invasive populations (except when invasions are at an early stage). We should rethink and reform traditional approaches to managing deer so that we can better integrate land vegetation with wildlife management to achieve broad public objectives. Interacting effects of high ungulate populations and invasive plants deserve further study to determine whether similar recommendations apply to other regions. [ABSTRACT FROM AUTHOR]

Questions: Deer‐proof fencing is an essential conservation tool to protect and recover plant species diversity in deer‐overbrowsed ecosystems, including species‐rich sub‐alpine grasslands. However, community‐level conservation tools (such as fencing) may be insufficient for single‐species conservation, particularly for non‐target endangered or rare species that are sparsely distributed. We examined whether fencing that can protect and recover total plant species richness also benefits non‐target endangered or rare species. Location: A sub‐alpine semi‐natural Kirigamine grassland in Nagano Prefecture, Japan. Methods: We conducted two complementary plant surveys (typical vegetation survey using 1‐m2 sampling units and flowering survey using 150‐m2 sampling units) to account for scarce species. We examined the community‐level responses (species richness, flowering species richness, and flowering abundance) of all species and endangered or rare species and the species‐level responses (occurrence and flowering abundance) of each species to deer fences. Results: Fencing benefited not only the community‐level response of all species, but also that of endangered or rare species. As species‐level responses, about half of 43 endangered or rare species had greater flowering abundance inside the fences than outside, but only three of them showed a positive effect on their occurrence. These results suggest that once an endangered or rare species has disappeared, it may be difficult to recover. Conclusions: Continued placement of deer fences is necessary to protect community‐level plant species richness of sub‐alpine endangered and rare species in deer‐overbrowsed ecosystems. We also highlight the necessity of additional strategies focusing on non‐target individual species across broad areas outside fences. [ABSTRACT FROM AUTHOR]

Questions: Sod cutting has been used extensively as an effective measure in removing excess N and restoring dwarf shrub dominance in heathlands affected by increased nitrogen deposition. However, recovery of other plant species is often very limited. One barrier is high soil acidity following sod cutting, which results in soil aluminium (Al3+) and ammonium (NH4+) reaching toxic concentrations. Sod‐cutting management also removes most of the major nutrients from the system, so intensified nutrient limitation could be an additional barrier to the recovery of species‐rich communities. Soil phosphorus (P) is of special interest as research indicates sod‐cutting management can shift the system to P limitation. Location: Hoge Veluwe National Park, The Netherlands. Methods: We set up a full‐factorial experiment in sod‐cut heathland formerly encroached by Molinia caerulea, adding phosphate (P+) and lime (Ca+) and over the next three growing seasons, we recorded soil chemistry and plant responses. Results: Soil inorganic N, especially soil NH4+, strongly declined after liming compared to the control situation, confirming that liming alleviates NH4+ toxicity. Addition of P resulted in a similar decline, also suggesting a role for soil phosphate availability in this process. Acid‐sensitive plant species richness increased significantly in both Ca+ and P+ treatment, whereas acid‐insensitive plant species richness only increased significantly as a result of P+ treatment. Mean vegetation relative growth rate increased significantly in both Ca+ and P+ treatments. Conclusions: Excessive P removal due to sod cutting constitutes a second barrier to restoration in addition to soil acidity. We discourage the large‐scale use of sod cutting to reduce soil N availability in heathlands and propose to use interventions that leave the soil nutrient balance intact, such as burning and grazing, mowing or litter removal, in combination with measures that restore the soil buffer capacity. [ABSTRACT FROM AUTHOR]

Past management practices may continue to influence ecosystem functions and processes for decades, centuries or even longer after they have been abandoned. Until now, few researchers have attempted experiments which test the effects of restoring some of these past management practices on long-term community developmental trajectories., Strong evidence indicates that the diversity of various taxonomic groups declined in European lowland forests in the second half of the 20th century, following the abandonment of some traditional forest management practices. We carried out a five-year field trial in a lowland thermophilous oak forest to describe the effects of restoration of litter raking and grass cutting on the long-term developmental trajectory of species composition and the diversity of understorey vegetation. We used target species groups, that is species specific to thermophilous forests and dry grassland vegetation and plant functional traits to evaluate the restoration success using both compositional and functional outcomes., Dissimilarity in species composition between the managed plots and controls increased significantly during the 5 years of the trial. Litter raking increased the richness and cover of the thermophilous forest and dry grassland species, whereas grass cutting increased the richness and cover of only the dry grassland species. We did not record any overall trends in divergence of functional trait composition between managed and control plots. In the litter raking plots, we recorded increases in community-weighted means of specific leaf area, in lateral spread and in Ellenberg indicator values for nutrients and soil reaction. In contrast, we found little evidence for predictability of species functional trait composition subjected to grass cutting., Synthesis and applications. Following the restoration of traditional forest management practices, we were able to change the community's developmental trajectory towards higher richness and cover of target species. The evaluation of community developmental trajectories using species and functional trait composition supports the idea that restoration of traditional forest management practices should carefully distinguish among possible interventions. [ABSTRACT FROM AUTHOR]

While phenology data (the timing of recurring biological events) has been used to explain and predict patterns related to global change, and to address applied environmental issues, it has not been clearly identified as pertinent for restoration. This opinion article thus aims to raise awareness of the potential of phenology to enhance the quality of restoration projects and ecological restoration theory. We based our analysis on a systematic literature survey carried out in February 2014, searching the words 'phenology' or 'phenological' in books dealing with restoration, the term 'phenolog*' in the journal Restoration Ecology, and the terms 'restoration' and 'phenolog*' in the database Web of Science until February 2014. We finally selected 149 studies relevant to our goals, and first classified them according to the context in which phenology was addressed. We then analyzed them within the framework of the five key steps of restoration projects: (1) the reference ecosystem; (2) biotic resources; (3) restoration methods; (4) monitoring; and (5) adaptive management. The literature survey showed that phenological information improved decision-making in the few restoration projects in which it was incorporated. We thus advocate taking phenological data into account at all stages of restoration when appropriate: from the acquisition of baseline data on the reference ecosystem to treatment design, and from restoration action planning and timing to monitoring. Phenological data should at minimum be collected for sown, keystone, dominant, and/or rare species to improve restoration quality. Phenology studies and monitoring should be promoted in future restoration guidelines. [ABSTRACT FROM AUTHOR]

Headwaters and small streams are crucial components of riverine systems, harbouring many highly specialized and unique invertebrate species. Unfortunately, the overwhelming majority of the Central European lowland headwaters are channelized, eutrophicated and/or polluted, and many related species have become critically endangered. Artificial streams established to drain some post-mining sites supplement a network of headwaters and generally do not suffer from agricultural pollution. Nevertheless, the biodiversity and conservation potential of the streams at post-mining sites has never been evaluated. We studied the biodiversity of dragonflies and damselflies (Odonata) at 53 sections (30 m) of an extraordinarily dense system of drainage ditches at a large lignite spoil heap in the Czech Republic. We recorded 22 dragonfly species, of which eight are threatened according to the national Red List. Moreover, four of them are closely associated with the endangered environment of small streams. Overall diversity was generally low at very tiny and/or narrowed streams and was also strongly reduced by high water velocity, high bankside inclination and dominance of expansive common reeds. Sufficient cover of rather shallow sediment layers strongly supports the studied diversity indicators. We thus conclude that post-mining streams in drainage ditches could have a strong potential to offer secondary habitats for threatened headwater biodiversity. However, intermittent reed suppression and the establishment of gently sloping banks and a structured stream bottom are necessary measures for maximizing post-mining stream conservation. [ABSTRACT FROM AUTHOR]

Long-term (10 years) growth responses of residual trees to prescribed fire and thinning were evaluated using standard dendrochronological protocols to understand the broader effects of the treatments on mixed-oak forest ecosystems in southern Ohio. Analysis of 696 increment cores (348 trees ≥ 25 cm DBH; five species) from 80 0.1 ha permanent plots distributed evenly across four treatments (control, thin, thin + burn, burn) indicated substantial increase in tree basal area increment (BAI) following the treatment. Post-treatment mean BAI of trees from the three active treatments ranged from 20.52 to 23.55 cm 2 y −1 compared with pre-treatment values of 16.86–17.07 cm 2 y −1. BAI rates (averaging 15.13 and 16.33 cm 2 y −1, respectively, for pre- and post-treatments) in the control plots did not change much over time. Mechanical treatments were more effective than prescribed fire at enhancing BAI of trees. However, basal area growth depended to some degree on the severity of prescribed fire. Analysis of percent BAI change revealed an interesting temporal trend with moderate to major growth releases during the first 5-year post-treatment period, and a slight attenuation thereafter, suggesting the need for periodic application of treatments to sustain growth over a longer timescale. Growth responses varied greatly among species, with yellow-poplar and hickories exhibiting the highest and lowest post-treatment BAI rates of 31.11 and 15.71 cm 2 y −1, respectively. Given their variable growth responses, integrating residual trees into current monitoring programs may help in elucidating the consequences of prescribed fire and thinning on forest dynamics and development. [ABSTRACT FROM AUTHOR]

Forest paths are characterised by a zonation in vegetation composition as a result of gradients in abiotical conditions and continued recreational impact. Little is known about how much seed bank composition is affected by recreation and the existing path structure. As it is difficult to assess the contribution of seed banks to vegetation restoration, this study imparts relevant knowledge to restore vegetation on paths which are closed for recreational use. We surveyed seed bank and field layer vegetation composition in transects across path ecotones in deciduous forest. Analysis concentrated on seed bank characteristics and similarities of the seed bank and field layer vegetation in terms of ecological and seed size groups. A total of 74 species and 9,815 seedlings germinated out of the seed bank samples. The total seed density does not differ between path zones, but significant differences exist in the depth distribution and composition of the seed bank throughout transects. There is a large discrepancy between the composition of the seed bank and the vegetation. Small seeded species of disturbed environments dominate in each path zone. Typical forest species dominate in the vegetation while their contribution to the seed bank is low. Only with reference to the proportion of species of forest edges and clearings, the seed bank and vegetation do not differ significantly. Similarity between the seed bank on the path centre and the vegetation in the respective path zones decreases towards the undisturbed forest vegetation. Some competitive species like Urtica dioica and Lythrum salicaria are excessively represented in the seed bank and efficiently may obstruct further visitor use. However, these early successional species may not contribute to the conservation values of forests. Therefore management should carefully consider alternative amendments (e.g. soil scarification and seeding) to stimulate vegetation restoration. [ABSTRACT FROM AUTHOR]

The transfer of hay from a donor site onto a receptor site is currently a widely accepted restoration procedure to establish grasslands with high biodiversity and rich in species. The impact of this procedure on vegetation has been well studied. However, its influence on the insect population has not been investigated. This study verifies that individuals ofMetrioptera bicolor(Orthopteroidea: Tettigoniidae) were successfully transferred with hay. Three individuals transferred with the hay were still able to reproduce after the hay transfer. This result corresponds to 4.6% of the 65 marked individuals that were mapped on the donor site on the day of hay transfer. Of the estimated 1220-3013 individuals on the donor site (8300 m2), 56-139 reproductively able individuals were transferred with the hay. Suitable habitat structures presupposed, this number is sufficient to initiate a persistent colonisation of the species on the receptor site. The loss rate ofM. bicolordue to grass cutting totalled 42%, which can be considered a very high mortality rate. Comparable studies on bush crickets show a medium loss rate of 21%, in relation to body size. [ABSTRACT FROM AUTHOR]

Abstract. Wooded meadows on the Baltic Island of Öland result from traditional agricultural management over centuries which has led to a species‐rich vegetation with high species diversity. Today, nearly all of these meadows have been abandoned and became rapidly overgrown by deciduous shrub and tree species forming a closed canopy which resulted in a rapid and strong decrease in species numbers of the herb layer. Recent efforts aim to restore overgrown wooded meadows by cutting single shrubs and trees to open the canopy. However, the effects of abandonment as well as of any restoration management in wooded meadows have rarely been documented until now. Mechanisms driving succession after restoration such as the dispersal potential of the respective species over time and space have not been analysed yet. Therefore, a chronosequence was studied which included a traditionally managed wooded meadow, an overgrown meadow which has been abandoned for more than 100 yr and a meadow which was restored 36 yr ago by cutting and is now grazed. We analysed the soil seed bank of the 3 meadows in comparison with the established vegetation and endozoochorous seed dispersal by cattle and sheep. After abandonment 87% of the typical grassland species vanished from the established vegetation and were replaced by species characteristic of woodland and disturbed grassland communities. The mean number of species decreased from 52 species per plot (4 m2) to 18 species. Mean species number and number of seeds in the seed bank declined significantly from the traditionally managed to the overgrown meadow. Most of the grassland species were assigned to a transient seed bank type while only 1/3 could be classified as having a short‐term persistent seed bank. Thus, restoration of wooded meadows cannot rely on the soil seed bank. Endozoochorous seed dispersal by cattle and sheep was shown for 15% of the species with seed densities per 100 g air dried dung of 737 and 767, respectively. Movement of animals between ancient and restored wooded meadows is recommended since many of the species only occurred in low densities and therefore, will probably not be found in the dung samples. [ABSTRACT FROM AUTHOR]

We resumed mowing in two plots of ca. 100 m2 in an abandoned meadow dominated by Brachypodium pinnatum on the slope of Monte Generoso (Switzerland). We monitored species composition and hay yieldusing point quadrats and biomass samples. Species frequencies changed little during 10 yr (1988-1997) while hay yields showed large fluctuations according to mean relative humidity in April-June. We performed a seed-addition experiment to test whether the establishment of meadow species is limited by lack of diaspores or favourable micrositesfor germination and recruitment from the seed bank. We sowed ca. 12,000 seeds of 12 species originating from a nearby meadow individuallyin plots of a 4 x 6 unbalanced Latin square with four treatments, burning, mowing, mowing and removal of a layer of decayed organic matter, and a control. We monitored the fate of seedling individuals for 24 months. Seedlings of all species were established and survived for 12 months, 10 species survived during at least 24 months, some reached a reproductive stage. Species responded to different qualities of microsites provided by the different treatments thus required different regeneration niches. Spontaneous long-distance immigration was insignificant. We conclude that the former species composition of abandoned meadows cannot easily be restored by mowing alone because many plant species of meadows do not have persistent seed banks and immigration over distances of more than 25 m and successful establishment is very unlikely. [ABSTRACT FROM AUTHOR]