Recovery Of Species Diversity Research Articles

Estimating the Impact of a Seasonal Fishing Moratorium on the East China Sea Ecosystem From 1997 to 2018

Fisheries management policies (FMPs) have been implemented in coastal countries to ensure a sustainable supply of seafood and the recovery of species diversity. Because of the depletion of fishery stocks, China has introduced a series of FMPs since 1995, including a seasonal fishing moratorium (SFM), a zero-growth strategy, and a minimum mesh size for fishing nets. Here, we built two mass balance models for 1997–2000 (M1997) and 2018–2019 (M2018) using Ecopath with Ecosim 6.6 to illustrate the interannual changes over the past two decades in the East China Sea (ECS). We then simulated two dynamic scenarios from 1997 to 2018, SFM (M2018SFM) and no SFM (M2018no-SFM), to test the role of the SFM under fishing pressure in the ECS. Ecopath showed that the ECS ecosystem is becoming more mature, although it is still unstable, featuring lower total primary production/total respiration, longer cycles, faster organic material circulation speed, and a higher omnivorous degree. This suggests a slow recovery for the ECS ecosystem in the past two decades. The biomass of fish in the ECS—especially the planktivores, dominated by small-sized Benthosema pterotum—significantly increased in M2018 versus M1997, but there were fewer medium- and large-sized fish. The keystone species switched from the planktivores/piscivores dominated by Decapterus maruadsi in M1997 to planktivores in M2018. Ecosim illustrated that the SFM has positive effects on fishery resources recovery, especially for commercial fishes (i.e., large yellow croakers and hairtails), as reflected by the significantly higher predicted biomass of fish in M2018SFM compared to M2018no-SFM and M1997, although the bioaccumulation was consumed by the intense fishing pressure after the SFM. However, the M2018SFM prediction for nektons was still lower than the actual value, especially for planktivores, which display a sharp increase in biomass. This should be partly attributable to the policy of the minimum mesh size (<5 cm was banned), which benefits B. pterotum due to its 3.5 cm maximum body size. Therefore, a series of FMPs, rather than only the SFM, functioned together in the ECS ecosystem. However, the mixed trophic impact indicated a negative impact if the fisheries were further developed. Fishery management in the ECS needs to be strengthened by extending the SFM and reducing fishing pressure after the SFM.

Regional landscape-scale comparison of species composition and recruitment in remnant tree patches 3 years after the 2011 Great East Japan Earthquake and tsunami

Understanding species composition and other characteristics of remnant trees that survive large-scale low-frequency disturbances such as tsunamis is an important step in monitoring and managing the process of recovery. This research was implemented in a study area along the shores of Sendai Bay, a region that was heavily damaged by the tsunami following the Great East Japan Earthquake of 2011. Field surveys of all the remnant patches of trees in the study area were conducted in 2014, three years after the disturbance. A total of 202 remnant patches were identified, and all the tree species, including both canopy trees and newly established seedlings, were recorded for each patch. The identified trees totaled 88 species, which were classified into three indicator-species types by a hierarchical cluster analysis. Comparisons based on species composition and similarity showed that species composition and other characteristics of the remnant patches were influenced by vegetation histories and other factors that only become visible at the regional landscape scale. The number of tree and seedling species per unit area was highest in patches that originated from pine plantations. Seven of the 25 seedling species identified were not present in any of the canopy layers in the study area, indicating that they dispersed from outside this area. These results show that, despite the immense scale of the tsunami, many diverse patches of trees managed to survive the disturbance. These patches function as hubs for species dispersion and accelerate recovery of species diversity in the disturbed area.

Are changes in remotely sensed canopy cover associated to changes in vegetation structure, diversity, and composition in recovered tropical shrublands?

The recovery of vegetation cover is a process that has important implications for the conservation of biodiversity and ecosystem services. Generally, the recovery of vegetation cover is documented over large areas using remote sensing, and it is often assumed that ecosystem properties and processes recover along with remotely sensed canopy cover. Here we analyze and compare the structure, composition, and diversity of trees and shrubs among plots established in a stratified random sampling design over four remotely sensed canopy cover change (CCC) categories defined according to a gradient in the percent of canopy cover. Plots were located in the Lake Cuitzeo basin (Mexico), where canopy recovery associated with agricultural abandonment has occurred in recent decades (1975–2000). We found that diversity measures, basal area, tree and shrub density, ground-truthed canopy cover, and mean plant height increased with increasing CCC category. However, Shannon index (H′) was lower in the CCC category with the most closed canopy cover category than in plots apparently not affected by agriculture. Furthermore, ordination analyses showed that composition of dominant species were not associated with CCC categories. Our results suggest that canopy closure in our study area is not associated with the recovery of species diversity, and does not result in similar species dominance as in sites not affected by agriculture.

Degradation and recovery of an alpine plant community: experimental removal of an encroaching dwarf bamboo

The dwarf bamboo Sasa kurilensis has responded to recent climate change by expanding its distribution into alpine snow meadows in Japan. Tall, dense clonal patches of bamboo suppress alpine plant growth, alter ecosystem functioning, and reduce diversity. We aim to assess the ecological impacts of bamboo expansion and the effectiveness of bamboo control for restoring alpine vegetation and species diversity. We quantified the extent of bamboo expansion, its effects on an alpine ecosystem, and the recovery of species diversity by bamboo removal over 6 years in Daisetsuzan National Park, northern Japan. We established paired, experimental plots assigned to either removal or control treatments following an encroaching gradient from interior to terminal locations in a large bamboo patch. We monitored bamboo development and aboveground production, and its impact on soil moisture and species diversity to assess the recovery process of snow meadow species after its removal. In control plots, bamboo density consistently increased and accumulated biomass from year to year. In the removal treatment, bamboo culm density, height and biomass decreased through time at all locations. Furthermore, soil moisture increased in the removal plots and remained consistently higher than controls throughout the growing season. Dwarf bamboo strongly suppressed alpine plants and reduced species diversity. However, alpine snow meadow species rapidly recovered and diversity increased through time in the removal treatment. This study presents an effective management strategy for restoring alpine plant diversity impacted by bamboo expansion under global climate change.

Amoxicillin-clavulanic acid and ciprofloxacin-treated SPF mice as gnotobiotic model

The experiment was carried out on 24 SPF BALB/c female mice and lasted for 15days with a 5-day antibiotic (ATB) treatment and then 10days without ATB treatment. The aim of our study was to acquire an animal model with reduced and controlled microflora and, at the same time, to ensure that the good health of these animals is maintained. Per oral administration of amoxicillin and clavulanate potassium in Amoksiklav (Sandoz, Slovenia) at a dose of 387.11mg/kg body weight (0.2ml of dilution per mouse) and subcutaneous administration of ciprofloxacin in Ciloxan (Alcon, Spain) at a dose of 18.87mg/kg body weight (0.1ml of dilution per mouse) were performed every 12h during first 5days of experiment. Five-day treatment with ATB led to a reduced survivability of microorganisms in faeces (28.33±0.43% on day 2) and caecum content (28.10±1.56%), where no cultivable microorganisms in faeces were present. Ten-day convalescence of decontaminated animals under gnotobiotic conditions prevented recovery of species diversity in mice gut microflora. This was reduced to two detectable cultivable species, namely Escherichia coli (GenBank KX086704) and Enterococcus sp. (GenBank KX086705) which were capable to restore its metabolic (CRL 2012) and morphological potential (Baratta et al. Histochem Cell Biol 131:713-726, 2009) within physiological range. Animals obtained under this procedure can be used in further studies. As a result, we created a mouse gnoto model with reduced and controlled microflora without alteration of the overall health status of the respective animals.

Regaining habitats from invasive weeds by planting limited-recruitment endemic trees on an oceanic island: successes and failures 11 years later

The degradation of biodiversity caused by anthropic habitat destruction is a global issue. The recovery of natural habitats from invasive alien weeds in order to conserve endemic ecosystems is especially important on small oceanic islands. Planting of endemic trees may be an effective measure, but a complete restoration process within the island is essential to avoid accidental introduction of invasive aliens. To test planting techniques, we planted two endemic tree species whose regeneration was hindered by alien species on degraded lands on Chichi-jima (Ogasawara Islands) and monitored vegetation changes. During an 11-year period, about half of the Elaeocarpus photiniifolius seedlings survived in gap areas, but all Morus boninensis failed. The E. photiniifolius trees reached a height of 4.7 ± 2.4 m. The restored canopy created a dark environment that greatly reduced the volume of the predominant invasive weeds. These results suggest that E. photiniifolius is suitable for restoration of forests on degraded land and for the suppression of weeds on the island. Low species diversity in the restored forests, however, was a remaining issue to be addressed. Herein we discuss potential improvement measures to facilitate the recovery of species diversity, including other native tree candidates.

Loss of secondary‐forest resilience by land‐use intensification in the Amazon

Summary Understanding how land‐use intensification affects forest resilience is a key for elucidating the mechanisms underlying regeneration processes and for planning more sustainable land‐use systems. Here, we evaluate how the intensification of a swidden cultivation system affects secondary‐forest resilience in the Amazon. Along a gradient of land‐use intensity, we analysed the relative role of management intensity, soil properties and landscape configuration in determining the resilience of early secondary forests (SFs). We assessed resilience as the recovery level of forest structure and species diversity achieved by SFs 5 years after abandonment. We used as a reference the recovery level achieved by SFs subjected to the lowest intensity of use, given that these SFs are part of a dynamic system and may not develop to old‐growth forests. Therefore, we interpreted a deviation from this reference level as a change in forest resilience. The recovery of forest structure was determined by management intensity, while the recovery of species diversity was driven by landscape configuration. With increasing number of cycles and weeding frequency along with decreasing fallow period and patch area, SF basal area and canopy height decreased, regeneration shifted from a seed‐ to sprout‐dependent strategy, and liana infestation on trees increased. With decreasing area covered by old‐growth forest, species richness and Shannon diversity decreased. Secondary‐forest resilience decreased with land‐use intensification, mainly mediated by the effect of management intensity upon regeneration strategies. Our findings demonstrate the – many times overlooked – importance of previous management intensity in determining the structure of SFs and highlight the importance of regeneration strategy for forest resilience. Synthesis. Swidden cultivation supports people's livelihoods and transforms landscapes in the tropics. The sustainability of this system depends on ecosystem services provided by SFs that develop during the fallow period. Land‐use intensification reduces the resilience of SFs and ultimately may drive the system towards an arrested succession state that holds a lower potential to deliver ecosystem services to the Amazonian people. Under an intensification scenario, the adaptation of management practices is needed to guarantee the resilience of swidden cultivation systems.

Recovery of species diversity and composition of braconid parasitic wasps after reforestation of degraded grasslands in lowland East Kalimantan

Human-induced disturbances and wildfires can transform areas of tropical rainforest into Imperata-dominated grassland, but it may be possible that recovery of biodiversity is facilitated by reforestation with fast-growing trees. We compared the assemblages of braconid wasps as parasitoids of taxonomically diverse groups of insects among Imperata grasslands, young and mature plantations of Acacia mangium, young secondary forests after wildfires, and old secondary forests in the lowland of East Kalimantan. The abundance and species richness of braconids, which had declined in Imperata grasslands, somewhat increased in Acacia plantations, and also the species composition of braconids in Acacia plantations was transitional between Imperata grasslands and old secondary forests. Parasitoids of detritivores and wood borers increased markedly after plantation, while those of herbivores showed a distinct turnover of species all over the range from grasslands to old secondary forests. The plantation of A. mangium had most likely facilitated the recovery of the diversity of host forest and their parasitoids, but the recovery was just at the rudimentary stage even in mature plantations. Monitoring of parasitic wasps would be useful to test the continuous recovery of forest biodiversity in plantation stands.

Low functional redundancy in coastal marine assemblages

AbstractThe relationship between species and functional diversity remains poorly understood for nearly all ecosystem types, yet determining this relationship is critically important for developing both a mechanistic understanding of community assembly and appropriate expectations and approaches to protecting and restoring biological communities. Here we use two distinct data sets, one from kelp forests in the Channel Islands, California, and one from a global synthesis of marine reserves, to directly test how variation in species diversity translates into changes in functional diversity. We find strong positive relationships between species and functional diversity, and increased functional diversity of fish assemblages coinciding with recovery of species diversity in marine reserves, independent of the method used for classifying species in functional groups. These results indicate that low levels of redundancy in functional species traits exist across a suite of marine systems, and that fishing tends to remove whole functional groups from coastal marine ecosystems.

Recovery of species diversity after disturbance of broad-leaved Korean pine mixed forest in Changbai Mountain

Recovery of species diversity after catastrophic disturbance was influenced by a few factors, such as intensity of disturbance, availability of propagules, and the environmental conditions. In this paper, we examined pattems of species development after nearly 60a succession in burned broad-leaved Korean pine mixed forest on northem slope of Changbai Mountain. We assessed the recovery of plant species diversity in 3 types of forests under the condition with gradient of soil moisture. Results revealed that recovery of plant species diversity varied greatly under different environmental conditions. Species richness of secondary forests greatly related to the site condition. Secondary birch forest on mesic site had the greatest number of plant species and the following was poplar-birch forest and larch-birch forest. Most of characteristic taxa could be found in birch forest after 60a succession. For larch-birch forest on hydra site, most of climax species were still not able to invade, so it had the lowest species diversity.

Effects of a Non‐Selective Arsenical Herbicide on Plant Biomass and Community Structure in a Fescue Meadow

Community structure and standing crop biomass of vegetation were affected similarly in a fescue meadow by single applications of sodium cacodylate and by severe heat stress. Recovery of species diversity and percentage similarly toward control levels was rapid, although not complete in one growing season. Repeated applications of the herbicide were necessary to suppress fescue growth, and this treatment regime caused sustained simplification of community structure and reductions in biomass throughout the growing season. Litter accumulated on heat—stressed areas, but its rapid decomposition on sprayed areas diminished an important nutrient sink and exposed the ecosystem of possible leaks in nutrient pools.