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opencc-zeroJul 2020View details →

Data from: Foraging by an avian ecosystem engineer extensively modifies the litter and soil layer in forest ecosystems

Ecosystem engineers physically modify their environment, thereby altering habitats for other organisms. Increasingly, 'engineers' are recognised as an important focus for conservation and ecological restoration because their actions affect a range of ecosystem processes and thereby influence how ecosystems function. The superb lyrebird Menura novaehollandiae is proposed as an ecosystem engineer in forests of south-eastern Australia due to the volume of soil and litter it turns over when foraging. We measured the seasonal and spatial patterns of foraging by lyrebirds and the amount of soil displaced in forests in the Central Highlands, Victoria. We tested the effects of foraging on litter, soil nutrients and soil physical properties by using an experimental approach with three treatments: lyrebird exclusion, lyrebird exclusion with simulated foraging, and non-exclusion reference plots. Treatments were replicated in three forest types in each of three forest blocks. Lyrebirds foraged extensively in all forest types in all seasons. On average, lyrebirds displaced 155.7 t/ha of litter and soil in a 12-month period. Greater displacement occurred where vegetation complexity (<50 cm height) was low. After two years of lyrebird exclusion, soil compaction (top 7.5 cm) increased by 37% in exclusion plots compared with baseline measures, whilst in unfenced plots it decreased by 22%. Litter depth was almost three times greater in fenced than unfenced plots. Soil moisture, pH and soil nutrients showed no difference between treatments. The enormous extent of litter and soil turned over by the superb lyrebird is unparalleled by any other vertebrate soil engineer in terrestrial ecosystems globally. The profound influence of such foraging activity on forest ecosystems is magnified by its year-round pattern and widespread distribution. The disturbance regime that lyrebirds impose has implications for diverse ecosystem processes including decomposition and nutrient cycling, the composition of litter- and soil-dwelling invertebrate communities, the shaping of ground-layer vegetation patterns, and fire behavior and post-fire ecosystem recovery. Maintaining lyrebird populations as a key facilitator of ecosystem function is now timely and critical as unprecedented wildfires in eastern Australia in summer 2019/2020 have severely burned ~12 million ha of forest, including ~30% of the geographic range of the superb lyrebird.

opencc-zeroAug 2020View details →

Soil organic carbon accumulation modes between pioneer and old-growth forest ecosystems

1. Increasing evidence suggests that high biomass and litterfall do not necessarily bring about soil organic carbon (SOC) sinks, contrary to the assumption that higher litterfall implies higher SOC when designing carbon models. The underlying mechanism is related to the quality of litter. 2. We conducted 15 years (2000–2015) of consecutive field measurements of δ13C values in SOC and plants in a pioneer forest (Pinus massoniana forest, PF) and an old-growth forest (monsoon evergreen broadleaved forest, BF), using an isotope mixing model based on mass balance to quantify the effects of vegetation on SOC stock and soil characteristics. 3. The carbon to nitrogen (C/N) ratio of litter in BF was lower than that in PF. The proportion of organic carbon yield input to the soil (Cinput) to the total litter carbon loss during decomposition was 38.7 ± 3.3% and 28.0 ± 2.1% in BF and PF, respectively. New carbon input was higher in BF (148.7 ± 8.8 g C m−2 yr−1) than PF (99.7 ± 4.5 g C m−2 yr−1), though there was a non-significant difference in annual litterfall between the two forests. Moreover, the Cinput was concentrated in the topsoil layer in PF but distributed in a more dispersed state across the whole soil profile in BF. Consequently, only the δ13C values of SOC decreased in the topsoil layer of PF, whereas these decreased at both soil depths in BF from 2000 to 2015. 4. Compared with PF, BF exhibited higher carbon input and a more favourable soil environment for carbon storage. It was the amount of intermediate product (i.e., Cinput) of litter decomposition, not the amount of litterfall itself, that drove the contrasting differences in SOC status. 5. Synthesis and applications. Litter quality controls SOC accumulation by regulating the fate of decomposing litter, which may explain why old-growth forests can sustainably accumulate carbon in soil. This finding questions the carbon models that predict the dependence of SOC accumulation on biomass and litter yield and suggests that litter quality should be valued in future carbon cycling models.30-Jul-2020

opencc-by-4.0Sep 2020View details →

Cs-137 in forests ecosystems contaminated by the Fukushima Daiichi Nuclear Power Plant Accident

We developed a dataset for radiocaesium (137Cs) in trees, soil, and mushrooms measured in the forests affected by the Fukushima nuclear accident. The 137Cs activity concentration and inventory data reported in scientific journal papers written in English or in Japanese, governmental reports, and governmental monitoring data on the web were collated. The ancillary information describing the forest stands were also collated, and environmental information was derived from the other databases using longitude and latitude coordinates of the sampling locations. The database consists of three separate files: 1) a data file, which contains radioactivity and ancillary data, 2) a field-description file, which explains the contents of the data file and the units of data, and 3) a reference list file, which contains the source number and the details of the reference. When the source has only a Japanese title, we translated the title into English, and included both titles in the reference list file.   Version 1.1 More descriptions have been added in "fields-description", and the data entry errors found in the review process have been modified.   The description of the dataset: Hashimoto et al. (2020) A dataset of 137Cs activity concentration and inventory in forests contaminated by the Fukushima accident, Scientific Data, 7 Article number 431. <a href="http://doi.org/10.1038/s41597-020-00770-1">doi: 10.1038/s41597-020-00770-1</a>  Contained in a journal's special "Collection": <a href="https://www.nature.com/collections/fhddajgafg">Infrastructure risk and disaster data / Nuclear disaster impact datasets</a>.   Funding: This study was supported by JSPS KAKENHI Grant Number 16H04945, and by research grants from FFPRI (#201501, #201901).

Data from: The impact of hurricanes Irma and Maria on the forest ecosystems of Saba and St. Eustatius, northern Caribbean

In September 2017, Irma became the first recorded category 5 hurricane to hit the Caribbean Windward Islands. The second category 5, Maria, followed two weeks later. In November 2017, we assessed the structural impact of this disturbance on highly valued Caribbean forest ecosystems. We recorded the status of 935 tree stems on Saba and St. Eustatius in stands at different elevations. Tree damage was substantial on both islands, with 93% of stems being defoliated, 84% having lost primary and/or secondary branches and 36% having structural stem damage. Average tree mortality was 18%, with mortality being nearly twice as high on St. Eustatius than on Saba. Surprisingly, we found that neither individual stem size nor community size distributions mediated the forests' response to the hurricanes. Our results show that these hurricanes comprised a density-independent disturbance, which may become more common as the frequency of strong hurricanes is projected to increase.

Data from: Can novel pest outbreaks drive ecosystem transitions in northern-boreal birch forest?

1. The boreal biome exhibits distinct alternative ecosystem states with high and low levels of tree-cover. Insect outbreaks facilitated by climate warming could potentially drive transitions from high to low tree-cover states. We investigated whether two key premises for such outbreak-induced transitions – critical thresholds (tipping points) and positive feedbacks that could maintain alternative states – are present in the northern-boreal mountain birch forest of Fennoscandia. Here, climate warming has promoted range expansions of defoliating geometrid moths, resulting in novel, severe multispecies outbreaks, most recently during 2002-2010. 2. We conducted regional-scale field surveys of forest damage and recovery in 280 mountain birch stands in a northeast Norway immediately after the outbreak (2010) and six years later (2016). Satellite-derived time series of the normalized difference vegetation index (NDVI) provided an index of stand defoliation during the outbreak period. 3. The proportion of dead stems per stand displayed a bimodal distribution, with stands generally being either lightly or severely damaged. This was due to a critical threshold in the relationship between defoliation and stem mortality, with mortality rates increasing abruptly in stands experiencing a mean drop in NDVI of more than 4 % during the outbreak. The two key forest regenerative pathways – basal sprouting and sapling production – both displayed positive feedbacks with surviving stems and trees, so that regeneration success declined with increasing damage to the mature tree layer. These feedbacks imply that stands which have been forced across critical defoliation thresholds and suffered collapses of living tree cover may struggle to recover, especially if the loss of positive regenerative feedbacks is compounded by ungulate browsing on birch recruits. 4. Synthesis. The north Fennoscandian mountain birch forest displays critical thresholds and positive feedbacks that conform to theoretical expectations for a system that could be vulnerable to abrupt and persistent changes of state in the face of novel, climatically facilitated insect outbreaks. These findings deepen the understanding of the persistent losses of tree-cover that have occasionally been observed after outbreaks in this system in the past, and adds to the list of mechanisms that could help explain the bistability of tree-cover across the boreal biome.

Data from: Can ecosystem functioning be maintained despite climate-driven shifts in species composition? Insights from novel marine forests

1. Climate change is driving a redistribution of species and reconfiguration of ecological communities at a global scale. Persistent warming in many regions has caused species to extend their geographical ranges into new habitats, with thermally-tolerant species often becoming competitively dominant over species with colder affinities. Although these climate-driven changes in species abundance and diversity are well documented, their ecosystem-level implications are poorly understood, and resolving whether reconfigured communities can maintain fundamental ecosystem functions represents a pressing challenge in an increasingly warmer world. 2. Here, we investigated how climate-driven substitutions of foundation species influence processes associated with carbon and nutrient cycling (biomass production, detritus flow, herbivory, decomposition) by comparing two habitat-forming kelp species with contrasting thermal affinities. We examined the wider consequences of the observed (and predicted) emergence of novel marine forests in the NE Atlantic, which are expected to become more dominated by range-expanding, warm-temperate kelps. 3. Warm-temperate kelps both accumulated and released 80% more biomass than the cold-temperate species despite being taxonomically closely-related and morphologically similar. Furthermore, the warm-temperate species accumulated biomass and released detritus year-round, whereas the cold-temperate species did so during short, discrete periods. The warm-temperate kelps supported higher densities of invertebrate grazers and were a preferred food source. Finally, their detritus decomposed 6.5 times faster, despite supporting comparable numbers of detritivores. Overall, our results indicate an important shift in the cycling of organic matter in kelp forests along parts of the NE Atlantic coastline following climate-driven expansion of a warm-affinity kelp, with novel forests supplying large amounts of temporally-continuous—yet highly labile—organic matter. 4. Synthesis. Collectively, our results show that, like species invasions, climate-driven range expansions and consequent shifts in the identity of dominant species can modify a wide range of important ecosystem processes. However, alterations in overall ecosystem functioning may be relatively limited where foundation species share similar ecological and functional traits.

opencc-zeroDec 2015View details →

Data from: The value of trophic interactions for ecosystem function: dung beetle communities influence seed burial and seedling recruitment in tropical forests

Anthropogenic activities are causing species extinctions, raising concerns about the consequences of changing biological communities for ecosystem functioning. To address this, we investigated how dung beetle communities influence seed burial and seedling recruitment in the Brazilian Amazon. First, we conducted a burial and retrieval experiment using seed mimics. We found that dung beetle biomass had a stronger positive effect on the burial of large than small beads, suggesting that anthropogenic reductions in large-bodied beetles will have the greatest effect on the secondary dispersal of large-seeded plant species. Second, we established mesocosm experiments in which dung beetle communities buried Myrciaria dubia seeds to examine plant emergence and survival. Contrary to expectations, we found that beetle diversity and biomass negatively influenced seedling emergence, but positively affected the survival of seedlings that emerged. Finally, we conducted germination trials to establish the optimum burial depth of experimental seeds, revealing a negative relationship between burial depth and seedling emergence success. Our results provide novel evidence that seed burial by dung beetles may be detrimental for the emergence of some seed species. However, we also detected positive impacts of beetle activity on seedling recruitment, which are probably because of their influence on soil properties. Overall, this study provides new evidence that anthropogenic impacts on dung beetle communities could influence the structure of tropical forests; in particular, their capacity to regenerate and continue to provide valuable functions and services.

Data from: Tree species richness increases ecosystem carbon storage in subtropical forests

Forest ecosystems are an integral component of the global carbon cycle as they take up and release large amounts of C in short time (C flux) or accumulate it over longer time (C stock). However, there remains uncertainty about whether and in which direction C fluxes and in particular C stocks may differ between forests of high vs. low species richness. Based on a comprehensive dataset derived from field-based measurements, we tested the effect of species richness (3–20 tree species) and stand age (22–116 years) on six compartments of above- and belowground C stocks and four components of C fluxes in subtropical forests in south-east China. Across forest stands, total C stock was 149 ± 12 Mg ha-1 with richness explaining 28.5% and age explaining 29.4% of variation in this measure. Species-rich stands had higher C stocks and fluxes than stands with low richness; and, in addition, old stands had higher C stocks than young ones. Overall, for each additional tree species the total C stock increased by 6.4%. Our results provide comprehensive evidence for diversity-mediated above- and belowground C sequestration in species-rich subtropical forests in south-east China. Therefore, afforestation policies in this region and elsewhere should consider a change from the current focus on monocultures to multi-species plantations to increase C fixation and thus slow increasing atmospheric CO2 concentrations and global warming.

opencc-zeroDec 2015View details →

Data from: Ecosystem carbon density and allocation across a chronosequence of longleaf pine forests

Forests can partially offset greenhouse gas emissions and contribute to climate change mitigation, mainly through increases in live biomass. We quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris Mill.) forests ranging in age from five to 118 years located across the southeastern USA and estimated above and belowground C trajectories. Ecosystem C stock (all pools including soil C) and aboveground live tree C increased nonlinearly with stand age and the modeled asymptotic maxima were 168 Mg C/ha and 80 Mg C/ha, respectively. Accumulation of ecosystem C with stand age was driven mainly by increases in aboveground live tree C, which ranged from <1 Mg C/ha to 74 Mg C/ha and comprised <1% to 39% of ecosystem C. Live root C (sum of below-stump C, ground penetrating radar measurement of lateral root C, and live fine root C) increased with stand age and represented 4% to 22% of ecosystem C. Soil C was related to site index, but not to stand age, and comprised 39% to 92% of ecosystem C. Live understory C, forest floor C, down dead wood C and standing dead wood C were small fractions of ecosystem C in these frequently burned stands. Stand age and site index accounted for 76% of the variation in ecosystem C among stands. The mean root to shoot ratio calculated as the average across all stands (excluding the grass stage stand) was 0.54 (standard deviation of 0.19) and higher than reports for other conifers. Long-term accumulation of live tree C, combined with the larger role of belowground accumulation of lateral root C than in other forest types, indicates a role of longleaf pine forests in providing disturbance-resistant C storage that can balance the more rapid C accumulation and C removal associated with more intensively managed forests. Although other managed southern pine systems sequester more C over the short-term, we suggest that longleaf pine forests can play a meaningful role in regional forest C management.

FIGURE 18 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 18. Map showing the location of Phong Nha - Ke Bang National Park (1) within Quang Binh Province, central Vietnam, and Tam Dao National Park (2) in the North of Vietnam.

FIGURE 15 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 15. Spotted slug snake (Pareas macularius) in its habitat in Phong Nha - Ke Bang (ZFMK 86446). Photo: Thomas Ziegler

FIGURE 12 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 12. Portrait of the preserved specimen of Lycodon cf. ruhstrati from Phong Nha - Ke Bang (ZFMK 86451). Photo: Thomas Ziegler

FIGURE 10 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 10. Green bush ratsnake (Gonyosoma prasinum) while passing a forest road in Phong Nha - Ke Bang (ZFMK 86443). Photo: Astrid Heidrich

FIGURE 8 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 8. Portrait of the preserved male Calamaria thanhi from Phong Nha - Ke Bang (SRC PNKB III '06-1). Photo: Thomas Ziegler

FIGURE 7 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 7. Thanh's reed snake (Calamaria thanhi), preserved male from Phong Nha - Ke Bang in ventral view (SRC

FIGURE 6 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 6. Thanh's reed snake (Calamaria thanhi), preserved male from Phong Nha - Ke Bang in dorsal view (SRC PNKB III '06-1). Photo: Thomas Ziegler

FIGURE 17 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 17. Snake families and species recorded for Phong Nha - Ke Bang, after Ziegler et al. (2006a) and new data (this paper).

FIGURE 9 in The diversity of a snake community in a karst forest ecosystem in the central Truong Son, Vietnam, with an identification key

FIGURE 9. Ventral view of the head of the preserved male Calamaria thanhi from Phong Nha - Ke Bang (SRC PNKB III '06-1). Photo: Thomas Ziegler