Relationship between Diversity and Stability of a Karst Plant Community

The relationships among species diversity, functional diversity, functional redundancy, and community stability are central to community and ecosystem ecology. This paper examines plant communities at different stages of vegetation restoration in the Guizhou karst plateau to study the relationship among functional diversity, functional redundancy, and stability of plant communities. The most important results include the following. (1) Species diversity (SD), functional redundancy (FR), and stability (STB) gradually increased with restoration, and there were significant differences among the different stages; functional diversity (FD) increased at first and then decreased, and reached the highest level at the tree irrigation stage. (2) Plant height (PLH) and specific leaf area (SLA) were functional traits that affected the diversity and stability of the plant community, and PLH was positively correlated with plant community diversity and stability, while SLA was negatively correlated with plant community diversity and stability. (3) During the community recovery, FD and FR interacted to maintain stability. In the early and late stages of recovery, the effect of functional redundancy on stability was greater than that of functional diversity, but it was the opposite in the middle stages. (4) The tree irrigation stage is the likely point at which the species diversity of plant communities in karst areas reached saturation, and the growth rate of functional redundancy after species diversity saturation was greater than that before saturation.

Why Do Communities Recover Differently after Socio-Natural Disasters? Pathways to Comprehensive Success of Recovery Projects Based on Bam’s (Iran) Neighborhoods’ Perspective

Although recent studies have provided explanations for the causes of success and failure in recovery projects following socio-natural disasters, there is a need for a concise understanding of how different combinations of factors may contribute to recovery failure or success. In this study, to examine the community recovery pathways after the 2003 Bam earthquake, we conducted a fuzzy-set qualitative comparative analysis of 11 neighborhoods in Bam city and Baravat (the neighborhoods represent the division of the areas damaged by the earthquake, as presented by local government). The success of socio-natural disaster recovery projects is presented in three pathways in which the absence or presence of public engagement had a significant influence on the results. The results indicate that a recovery project should respond to the needs of the project within the continuous lifecycle of the project. Additionally, on the one hand, public participation and prompt rescue operations have a significant effect on project success. On the other hand, neglecting the needs of people and the area’s climate in housing design have led to project failure. It is expected that the findings from this study can be used to develop strategies for empowering people in recovery projects and to develop housing guidelines that respect residents’ needs while focusing on on-time and sufficient rescue processes. However, care should be taken when applying the present findings in practice, because every socio-natural disaster is unique and requires careful consideration of complex sets of features.

Temporal variation of patch connectivity determines biodiversity recovery from recurrent disturbances

Understanding the capacity of ecological systems to withstand and recover from disturbances is a major challenge for ecological research in the context of environmental change. Disturbances have multi-scale effects: they can cause species extinctions locally and alter connectivity between habitat patches at the metacommunity level. Yet, our understanding of how disturbances influence landscape connectivity remains limited. To fill this gap, we develop a novel connectivity index that integrates the temporal variation of patch connectivity induced by disturbances, which can be applied to any spatially-structured habitat. We then combine this index with a metacommunity model to specifically investigate biodiversity recovery from drying events in river network metacommunities. We demonstrate that patch connectivity explains variations of species richness between groups of organisms with contrasting dispersal modes and captures the effect of drying intensity (i.e., fraction of patches that dry-up) and drying location on community recovery. As a general rule, loss of patch connectivity decreases community recovery, regardless of patch location in the river network, dispersal mode, or drying intensity. Local communities of flying organisms maintained higher patch connectivity in drying river networks compared to organisms with strictly aquatic dispersal, which explained the higher recovery capacity of this group from drying events. The general relationship between patch connectivity and community recovery we found can be applied to any spatial network subject to temporal variation of connectivity, thus providing a powerful tool for biodiversity management in dynamic landscapes.

Recovery of Subtidal Benthic Macroinvertebrate Communities Following Natural and Experimental Disturbances

<p>The recovery processes of subtidal benthic macroinvertebrate communities following large-scale natural and meso-scale experimental disturbances were studied in Wellington Harbour, New Zealand, a temperate semi-enclosed embayment. This is the first time that long-term effects (>1 year post-disturbance) of a naturally occurring toxic plankton bloom have been investigated in the Southern hemisphere. For 2 years macroinvertebrate communities were studied at three sites of differing hydrodynamic regime. Samples were taken with a Van Veen grab and washed through a 500 [mu]m mesh. Community recovery following the bloom was site-specific. Multivariate analyses revealed that at two sites community recovery was not completed >3 years post-bloom, whereas at the third site the community composition oscillated from year to year, but did not show any signs of a sequential recovery process. The hydrodynamic regime was identified as a major factor influencing the observed recovery processes. Communities exposed to an active hydrodynamic regime were less affected by the bloom and recovered faster, as they were naturally in a perpetual state of recovery as indicated by a dominance of r-selected species. The community at the hydrodynamically less active site was more affected by the bloom. Complete recovery to the pre-disturbance climax community dominated by K-selected species was estimated to take 4-5 years, if not interrupted by other disturbances. For the first time a defaunation experiment was conducted in a hydrodynamically active site to mimic the effects of a plankton bloom on the benthic macroinvertebrate community. Three sediment plots of 25 m2 were covered by plastic tarpaulins, thereby creating a benthic die-off caused by oxygen depletion. This method of defaunation had not been used in the subtidal before. Community recovery was studied for 1 year and compared with community composition in undisturbed control plots. Macroinvertebrate samples were taken by diver-operated cores and washed through a 500 [mu]m mesh. Recovery was slow until after 70 days when abundance and number of species increased synchronously in disturbed and control plots. Multivariate analyses showed that community composition fluctuated strongly in the first 100 days. After 1 year, although disturbed and control communities were converging, differences in community composition were still significant. Time for complete recovery was estimated to be approximately 2 years. Predictions of current succession models were generally fulfilled in both studies. Recovered communities were similar in their composition to either pre-disturbance or surrounding communities. The major deviation from model predictions was that no abundance peak of opportunistic species occurred in either study. Timing of the disturbance, in both studies past the major macroinvertebrate recruitment peak, and the hydrodynamic regime were identified as major factors influencing recovery processes of the communities studied. Such deviation from model predictions indicates that the general models cannot take into account the multiplicity and complexity of factors influencing recovery processes. Thus, their applicability in predicting recovery times and endpoints for specific disturbances at specific locations is limited. Location-specific models might be a useful alternative. Recommendations are made to combine uni- and multivariate techniques to assess recovery processes due to their different sensibilities to changes in community composition.</p>

Recovery of Subtidal Benthic Macroinvertebrate Communities Following Natural and Experimental Disturbances

<p>The recovery processes of subtidal benthic macroinvertebrate communities following large-scale natural and meso-scale experimental disturbances were studied in Wellington Harbour, New Zealand, a temperate semi-enclosed embayment. This is the first time that long-term effects (>1 year post-disturbance) of a naturally occurring toxic plankton bloom have been investigated in the Southern hemisphere. For 2 years macroinvertebrate communities were studied at three sites of differing hydrodynamic regime. Samples were taken with a Van Veen grab and washed through a 500 [mu]m mesh. Community recovery following the bloom was site-specific. Multivariate analyses revealed that at two sites community recovery was not completed >3 years post-bloom, whereas at the third site the community composition oscillated from year to year, but did not show any signs of a sequential recovery process. The hydrodynamic regime was identified as a major factor influencing the observed recovery processes. Communities exposed to an active hydrodynamic regime were less affected by the bloom and recovered faster, as they were naturally in a perpetual state of recovery as indicated by a dominance of r-selected species. The community at the hydrodynamically less active site was more affected by the bloom. Complete recovery to the pre-disturbance climax community dominated by K-selected species was estimated to take 4-5 years, if not interrupted by other disturbances. For the first time a defaunation experiment was conducted in a hydrodynamically active site to mimic the effects of a plankton bloom on the benthic macroinvertebrate community. Three sediment plots of 25 m2 were covered by plastic tarpaulins, thereby creating a benthic die-off caused by oxygen depletion. This method of defaunation had not been used in the subtidal before. Community recovery was studied for 1 year and compared with community composition in undisturbed control plots. Macroinvertebrate samples were taken by diver-operated cores and washed through a 500 [mu]m mesh. Recovery was slow until after 70 days when abundance and number of species increased synchronously in disturbed and control plots. Multivariate analyses showed that community composition fluctuated strongly in the first 100 days. After 1 year, although disturbed and control communities were converging, differences in community composition were still significant. Time for complete recovery was estimated to be approximately 2 years. Predictions of current succession models were generally fulfilled in both studies. Recovered communities were similar in their composition to either pre-disturbance or surrounding communities. The major deviation from model predictions was that no abundance peak of opportunistic species occurred in either study. Timing of the disturbance, in both studies past the major macroinvertebrate recruitment peak, and the hydrodynamic regime were identified as major factors influencing recovery processes of the communities studied. Such deviation from model predictions indicates that the general models cannot take into account the multiplicity and complexity of factors influencing recovery processes. Thus, their applicability in predicting recovery times and endpoints for specific disturbances at specific locations is limited. Location-specific models might be a useful alternative. Recommendations are made to combine uni- and multivariate techniques to assess recovery processes due to their different sensibilities to changes in community composition.</p>

Trait-based responses to cessation of nutrient enrichment in a tundra plant community

Plant communities worldwide show varied responses to nutrient enrichment—including shifts in species identity, decreased diversity, and changes in functional trait composition—but the factors determining community recovery after the cessation of nutrient addition remain uncertain. We manipulated nutrient levels in a tundra community for 6 years of nutrient addition followed by 8 years of recovery. We examined how community recovery was mediated by traits related to plant resource-use strategy and plant ability to modify their environment. Overall, we observed persistent effects of fertilization on plant communities. We found that plants with fast-growing traits, including higher specific leaf area, taller stature and lower foliar C:N, were more likely to show a persistent increase in fertilized plots than control plots, maintaining significantly higher cover in fertilized plots 8 years after cessation of fertilization. Additionally, although graminoids responded most strongly to the initial fertilization treatment, forb species were more vulnerable to fertilization effects in the long-term, showing persistent decline and no recovery in 8 years. Finally, these persistent fertilization effects were accompanied by modified environmental conditions, including persistent increases in litter depth and soil phosphorous and lower soil C:N. Our results demonstrate the potential for lasting effects of nutrient enrichment in nutrient-limited systems and identify species traits related to rapid growth and nutrient-use efficiency as the main predictors of the persistence of nutrient enrichment effects. These findings highlight the usefulness of trait-based approach for understanding the persistent feedbacks of nutrient enrichment, plant dynamics, and niche construction via litter and nutrient build-up.

Spatial Assessment of Community Resilience from 2012 Hurricane Sandy Using Nighttime Light

Quantitative assessment of community resilience is a challenge due to the lack of empirical data about human dynamics in disasters. To fill the data gap, this study explores the utility of nighttime lights (NTL) remote sensing images in assessing community recovery and resilience in natural disasters. Specifically, this study utilized the newly-released NASA moonlight-adjusted SNPP-VIIRS daily images to analyze spatiotemporal changes of NTL radiance in Hurricane Sandy (2012). Based on the conceptual framework of recovery trajectory, NTL disturbance and recovery during the hurricane were calculated at different spatial units and analyzed using spatial analysis tools. Regression analysis was applied to explore relations between the observed NTL changes and explanatory variables, such as wind speed, housing damage, land cover, and Twitter keywords. The result indicates potential factors of NTL changes and urban-rural disparities of disaster impacts and recovery. This study shows that NTL remote sensing images are a low-cost instrument to collect near-real-time, large-scale, and high-resolution human dynamics data in disasters, which provide a novel insight into community recovery and resilience. The uncovered spatial disparities of community recovery help improve disaster awareness and preparation of local communities and promote resilience against future disasters. The systematical documentation of the analysis workflow provides a reference for future research in the application of SNPP-VIIRS daily images.

Te Rito Toi in New Zealand: A Caring Response to the Pandemic

Te Rito Toi is an online open access educational resource designed to help teachers respond to the extraordinary circumstances of the pandemic and provide all children with opportunities to engage with the arts. Central to the Te Rito Toi project was the concept of well-being, one of the United Nations Sustainable Development Goals (SGD 3). The study reported in this article delved into the perspectives of a group of New Zealand educators who used Te Rito Toi after the Covid-19 lockdown to explore the ways in which this resource helped them to engage their students in both individual and collective recovery. The analysis of the interviews revealed the following four themes: 1) building relationships and a sense of belonging; 2) enhancing communication and empathy; 3) connecting with wider social issues; and 4) contributing to community recovery.