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opencc-by-4.0Jul 2021View details →

Determination of the Optimal Parameters for Self-Healing Efficiency of Encapsulated bacteria in Concrete Simulated Subtropical Climate

Concrete is a remarkable construction material. However, its low tensile strength makes it prone to cracking, which negatively affects its durability. To address this issue, bacterial concrete has been implemented as a self-healing alternative due to its capability to seal microcracks through microbial-induced calcium carbonate precipitation (MICCP). In this study, a bacterial strain (i.e, Bacillus Pseudiformus) was encapsulated through three different methods: encapsulation through hydrogel beads, vacuum impregnation on lightweight aggregates, and attachment to cellulose nanocrystals. Furthermore, three precursor types were used, magnesium acetate, calcium lactate, and sodium lactate were implemented. Compressive strength tests and flexural strength tests were performed on mortar specimens to characterize their mechanical properties. Once the crack was induced, samples were subjected to 28 days of wet/dry cycles in which the corresponding crack width was monitored. At the end of this period, the beams were retested to determine the strength recovery of the specimens. The results showed that the specimen groups in which calcium lactate was added to the cementitious matrix displayed the highest values in compressive strength. In terms of flexural strength, no major difference was found among the specimens. Moreover, the flexural strength recovery of the specimens did not show any significant difference as well. In terms of the healing efficiency, the sample that displayed the best results was the one containing calcium lactate as a precursor along with bacteria and yeast extract encapsulated in hydrogel beads. In addition, scanning electron microscopy (SEM) along with x-ray energy dispersive spectroscopy (EDS) was performed on the cracked specimens to characterize the healing products. Furthermore, a scale study was performed on concrete samples to determine the long-term implications of adding encapsulated bacteria along with calcium lactate and yeast extract in concrete.

opencc-zeroDec 2021View details →

Fire and forage quality: post-fire regrowth quality and pyric herbivory in subtropical grasslands of Nepal

Indiscriminate fire is rampant throughout subtropical South and Southeast Asian grasslands. However, very little is known about the role of fire and pyric herbivory on the functioning of highly productive subtropical monsoon grasslands lying within Cwa-climatic region. We collected grass samples from 60 m x 60 m plots and determined vegetation physical and chemical properties at regular 30-day intervals from April to July 2020, starting from 30 days after fire to assess post-fire regrowth forage quality. We counted pellet groups for the same four months from 2 m x 2 m quadrats that were permanently marked with pegs along the diagonal of each 60 m x 60 m plot to estimate grazing intensity to the progression of post-fire regrowth. We observed strong and significant reductions in crude protein (mean value 9.1 to 4.1 [55% decrease]) and phosphorus (mean value 0.2 to 0.11 [45% decrease]) in forage collected during different time intervals i.e., from 30 days to 120 days after fire. Mesofaunal deer utilised the burned areas extensively for a short period, i.e., up to two months after fire when the burned areas contained short grasses with a higher level of crude protein and phosphorus. Grazing intensity of chital (Axis axis) to post-fire regrowth differed significantly over time since fire, with higher intensity of use at 30 days after fire. Grazing intensity of swamp deer (Rucervus duvaucelii) did not differ significantly until 90 days after fire, however, decreased significantly after 90 days since fire. Large-scale indiscriminate single event fires thus may not fulfil nutritional requirements of all species in mesofaunal deer community in these subtropical monsoon grasslands. We recommend for a spatio-temporal manipulation of fire to reinforce grazing feedback and to yield for the longest possible period a reasonably good food supply for the conservation of mesofaunal deer.

opencc-zeroMay 2022View details →

Plant-root pathogenic fungal and plant-mycorrhizal fungal association networks in a subtropical forest

Although rhizosphere fungi are essential for plant survival and ecosystem functioning, little is known about the processes that structure plant–fungal association networks. In this study, we constructed association networks between 43 plant species and two groups of root-associated fungi (mycorrhizal and pathogenic fungi; MF and PF, respectively) in a diverse subtropical forest. We then evaluated the modularity of plant–MF and plant–PF networks and linked them to the functional traits and phylogenies of both plants and fungi. We observed strong modularity in both plant–MF and plant–PF networks. Phylogenetically related fungi tended to emerge in the same modules. MF from distinct modules associated with plants with different specific root length and specific root area in plant–MF networks. PF from distinct modules associated with plants with different dark respiration rate and light compensation point in plant–PF networks. Plant affiliation to modules was explained by both plant traits and phylogeny (22% for plant–MF and 37% for plant–PF networks). In contrast, fungal affiliation to modules was explained by fungal phylogeny (16% for plant–MF and 29% for plant–PF networks). Our results elucidate the link between modularity in plant–root fungal networks and the functional traits and phylogeny of the plants and fungi. Our study highlights the importance of traits and phylogeny in governing root fungal community assembly from network perspective.

opencc-zeroMay 2022View details →

Data from: UV radiation doubles microbial degradation of standing litter in a subtropical forest

UV radiation has been recognized as a direct driver of litter decomposition by photodegrading organic matter in dryland ecosystems. However, the importance and mechanism of UV radiation on litter decomposition, especially on standing litter, in humid forest ecosystems remain unclear. We conducted a factorial experiment in a humid subtropical forest gap, manipulating the effects of UV radiation on the decomposition of standing litter under different microbial conditions. After 366 days of standing incubation, under normal conditions (UV pass with microorganisms), up to 40.63% of the litter mass was lost. However, under a UV pass without microorganisms, litter mass loss was only 16.30%. Under a UV block, the mass loss of litter with microorganisms was 27.68% and that of litter without microorganisms was 15.54%. Without microorganisms, UV radiation had no significant effect on the mass loss of litter carbon. However, UV radiation increased the DOC concentration of litter. And in the presence of microorganisms, UV radiation contributed to an increased mass loss of lignin by 16.72% and of cellulose by 14.75%. No negative effects of UV radiation on microorganisms were observed. These results suggest that UV radiation increased the net mass loss of litter by 106.67%, and this doubling promotion was achieved through microbial degradation. Synthesis. The increase in microbial degradation under UV radiation may be linked to the increased degradability of lignin and cellulose caused by photodegradation. Our study indicates that direct photodegradation by UV radiation could be weak in subtropical forests, but UV photofacilitation generates rapid turnover of carbon in this system.

opencc-zeroJun 2022View details →

Climate and mycorrhizae mediate the relationship of tree species diversity and carbon stocks in subtropical forests

1. It is increasingly being recognized that tree species diversity has positive effects on forest ecosystem carbon (C) stock. However, at broad spatial scales this relationship may depend on climate conditions and species mycorrhizal associations. 2. Here, observations from 667 forest plots in subtropical China, were used to investigate the effects of species diversity, mean annual precipitation (MAP), mean annual temperature (MAT) and mycorrhizal type (arbuscular or ectomycorrhizal) on the forest C stock and its components (tree C stock, shrub layer C stock, herb layer C stock, litter layer C stock, root C stock and soil C stock). 3. We found positive effect of tree species diversity on total forest C stock. MAP had positive effects on total forest C stock and its components, while MAT had consistently negative effects on total forest C stock and most of its components. Different levels of MAP and MAT did modulate the strength of effect of species diversity on forest C stock and its components. In addition, species diversity, MAT and MAP showed a significant positive relationship with arbuscular mycorrhiza-associated tree C stock but had no or negative relationship with ectomycorrhiza-associated tree C stock. 4. Synthesis. Our results indicate that maintaining high level of species diversity may support the buffering of negative effects resulting from climate warming. Furthermore, under climate warming the specific C stock of AM trees can increase, which can potentially promote forest C stock. Taken together, our study suggests that afforestation policies should consider not only tree species diversity to increase forest C stock but also the effects of different tree mycorrhizal types.

opencc-zeroJul 2022View details →

Ecological drivers of avian diversity in a subtropical landscape: effects of habitat diversity, primary productivity and anthropogenic disturbance

Understanding the roles of ecological drivers in shaping biodiversity is fundamental for conservation practice. In this study, we explored the effects of elevation, conservation status, primary productivity, habitat diversity, and anthropogenic disturbance (represented by human population density and birding history) on taxonomic, phylogenetic and functional avian diversity in a subtropical landscape in southeastern China. We conducted bird surveys using 1-km transects across a total of 30 sites, of which 10 sites were located within a natural reserve. Metrics of functional diversity were calculated based on six functional traits (body mass, clutch size, dispersal ratio, sociality, diet and foraging stratum). We built simultaneous autoregression models to assess the association between the ecological factors and diversity of the local avian communities. Local avian diversity generally increased with increasing habitat diversity, human population density and primary productivity. We also detected phylogenetic and functional clustering in these communities, suggesting that the avian assemblages were structured mainly by environmental filtering, rather than interspecific competition. Compared to sites outside the natural reserve, sites within the natural reserve had relatively lower avian diversity but a higher level of phylogenetic heterogeneity.

opencc-by-4.0Aug 2022View details →

Molecular Level Estimation of the Composition and Fate of Dissolved Organic Matter in Fire-Impacted Temperate and Subtropical Peatlands

Calculated values of optical (UV-visible and fluorescence) spectroscopy parameters and molecular formulas determined by ultrahigh resolution mass spectrometry for dissolved organic matter (DOM) in porewaters from a temperate and sub-tropical peatland. These data were used to generate figures in a manuscript submitted to the Journal of Geophysical Research - Biogeosciences.

opencc-by-4.0Jul 2022View details →

Data_Changes in Tree Diversity, Structure and Functional Trait Identity Drive Biomass Increase along Elevational Gradients in Subtropical Forests of Southern China

In this article "Changes in Tree Diversity, Structure and Functional Trait Identity Drive Biomass Increase along Elevational Gradients in Subtropical Forests of Southern China", these files contain community inventory data collected at our three study sites.

opencc-zeroOct 2022View details →

Spatio-temporal variation in deep soil water use patterns of overstory and understory layers in subtropical plantations predict community assembly

1. Deep soil water utilization allows plants to cope with drought stress. However, little is known about the roles of the understory layers in driving spatio-temporal variations of deep soil water in forests and how the patterns of deep soil water use among life forms contribute to community assembly processes. 2. We assessed the spatio-temporal patterns and determinants of deep water utilization of tree, shrub and herb layers in subtropical coniferous plantations and investigated associations between deep water use parameters and dominance and richness of understory vegetation. 3. We found that the understory layer had a higher reliance on deep soil water in the dry season, a larger seasonal plasticity of deep soil water uptake, but lower spatial variability in deep soil water utilization than the tree layer. We showed that greater reliance of the tree layer on deep soil water was associated with decreased shrub layer diversity, whereas greater reliance of the shrub layer on deep water was associated with increased herb layer diversity. 4. Synthesis. Our results highlight the roles of understory layers in driving the temporal dynamics of deep soil water in forests and improve our understanding of how deep soil water use patterns amongst life forms shape community assembly in forests.

opencc-by-4.0Jun 2022View details →

Figs 1–6 in New records of tropical and subtropical noctuoid moths (Lepidoptera: Erebidae, Nolidae) from Primorsky krai, Russia

Figs 1–6. Habitus (1, 2, 4, 5) and genitalia (3, 6) of Erebid moths from Primorsky krai (5

Figure 5 in Phyllostomid bats distribution and richness gradient in a subtropical Brazilian state

Figure 5. Box plot showing that the species richness predicted for the Serra do Mar is larger than for any other ecoregion of the Santa Catarina. Box plots show medians (vertical line) and each box is bounded by the 25th and 75th percentiles.The horizontal lines extend to the 5th and 95th percentiles. Outliers are indicated by dots. *** p-value <0.001.

Figure 3. Potential distribution for 10 in Phyllostomid bats distribution and richness gradient in a subtropical Brazilian state

Figure 3. Potential distribution for 10 species of phyllostomid bats from Santa Catarina, southern Brazil, generated through the Maxent algorithm and bioclimatic variables.The climate suitability values range from 0 (gray regions on the map) to 1 (red regions on the map). Black dots indicate the ocurrence records used to build the models.

Figure 4 in Phyllostomid bats distribution and richness gradient in a subtropical Brazilian state

Figure 4. Phyllostomid bats richness gradient predicted for Santa Catarina, Southern Brazil, and its association with Protected Areas. The map was obtained by stacking maps of species potential distribution generated through the Maxent algorithm.

Figure 1 in Phyllostomid bats distribution and richness gradient in a subtropical Brazilian state

Figure 1. Santa Catarina state (southern Brazil) and its main ecoregions, according to Olson et al. (2001).

Figure 2. Potential distribution for 10 in Phyllostomid bats distribution and richness gradient in a subtropical Brazilian state

Figure 2. Potential distribution for 10 species of phyllostomid bats from Santa Catarina, southern Brazil, generated through the Maxent algorithm and bioclimatic variables. The climate suitability values range from 0 (gray regions on the map) to 1 (red regions on the map). Black dots indicate the ocurrence records used to build the models.

opencc-zeroOct 2022View details →

Data from: Variations of trophic structure and niche space in fish community along a highly regulated subtropical large river

The trophic interactions between consumers and resources play a vital role in the stability of communities. In river systems, fragmentation of natural habitats and environmental changes alters the energy basis and community composition, consequently leading to variations in the community's trophic structure and niche space. However, our understanding of how the trophic structure responds to environmental changes is still very limited. Here, based on stable isotope data, we explored and compared trophic positions (TPs), community-wide trophic metrics, and isotope niche space of fish communities in three reaches with different hydrogeomorphic conditions along a highly regulated subtropical river over three seasons. The community trophic structure and niche space showed notable spatiotemporal variations. Overall, the downstream reach had lower TPs and trophic diversity but higher trophic redundancy. The middle reach occupied a wider isotope niche space than other reaches, with the largest niche size during autumn. Furthermore, the niche overlap was relatively high in winter between reaches and in the downstream between seasons. The results implied a homogenization of feeding functional groups and energy flow pathways of species in the downstream community associated with the change of energy source and stability of hydrological conditions. The relationship between trophic structure and environmental factors suggested that the dam-induced alteration in hydrological-related aspects may drive the changes in the functional group composition, together with changes in energy basis, resulting in differences in the trophic structure of the community. The results of the present study deepen our understanding of how ecosystem functions respond to disturbance, thus contributing to an improved ability to conserve river ecosystems.

opencc-zeroOct 2022View details →

Recent photosynthates are the primary carbon source for soil microbial respiration in subtropical forests

Tropical and subtropical forests represent the largest terrestrial carbon pool. Elucidating the carbon sources for soil microbial respiration (Rm) in tropical and subtropical forests is of fundamental importance to the global carbon cycle in a warming world. Based on hourly measurements, we quantified Rm of in situ forest soil and soil cores from a subtropical forest. We found recent photosynthates, not soil organic carbon (SOC), contributed 88% ± 12% of the carbon source fueling Rm. The control of recent photosynthates on Rm is also supported by the close relationship between Rm and photosynthetically active radiation as well as literature data synthesis results. These results challenge conventional models based on the tenet that Rm is mainly regulated by soil temperature in all forest ecosystems. The results imply that the widely observed warming-induced Rm increases are largely explained by the enhanced input of recent photosynthates in tropical forests, not SOC consumption.

opencc-by-4.0Dec 2017View details →

Meteorological and Ecosystem Flux Data for: Climate Change Impacts on Net Ecosystem Productivity in a Subtropical Scrubland of Northwestern México

This dataset accompains the paper: Climate Change Impacts on Net Ecosystem Productivity in a Subtropical Scrubland of Northwestern México which is submitted for publication at the Journal of Geophysical Research - Biogeosciences  With this data set, we calibrate and validate an ecohydrological and a soil carbon model to assess climate change impacts in a subtropical scrubland located in northwest México. Model calibration and validation is performed using five continuous years of water, energy and carbon flux measurements from an eddy covariance tower and remotely-sensed vegetation indices.

opencc-zeroMay 2024View details →

Data from: Can faster growth compensate for increased mortality in subtropical dry forest fragments?

Capturing the effects of fragmentation and ongoing changing climate on the population dynamics of long-lived trees requires long-term datasets, but these are uncommon in rainforests and dry forests outside of the tropics. This study capitalised on nine 0.04-ha permanent plots established in 1982 within corridors of old-growth subtropical dry forest (Araucarian vine forest) retained as fire breaks within forestry plantations in Imbil (southern Queensland, Australia). Tree diameter growth and survival were censused in 1997 and 2021, resulting in two monitoring periods. The most recent period was associated with an increasing trend in vapour-pressure deficit (VPD). Consistent with this trend, we found that survival was substantially lower across all size classes in the second period. Mortality-induced reductions in stem density were associated with faster growth rates in all but the largest stems in the second period. Growth was also moderately faster in plots near forest edges in the second period. The richness of obligate understory species declined significantly by an average of 1.44 species over the 40-year study period. Synthesis and applications: Overall, our results are consistent with increasing tree mortality rates reported recently for the Australian wet tropics and suggest widespread and alarming impacts of increasing VPD on rainforest and dry forest community dynamics. To increase forest resilience in a changing climate, we recommend the retention of a buffer of plantation trees adjacent to old growth forest corridors; widening the forest corridors using faster-growing species identified in this study and maintaining connections between scrub breaks and larger tracts of forest for species dispersal.