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7,883 results for “Tropic”
Data from: Litter removal in a tropical rain forest reduces fine root biomass and production but litter addition has few effects
Many old-growth lowland tropical rain forests are potentially nutrient limited, and it has long been thought that many such forests maintain growth by recycling nutrients from decomposing litter. We investigated this by continuously removing (for ten years) freshly fallen litter from five (45 m x 45 m) plots, adding it to five other plots, there were five controls. From monthly measures over one year we show that litter removal caused lower: fine root (≤2 mm diameter) standing mass, fine root standing length, fine root length production and fine root length survivorship. Litter addition did not significantly change fine root mass or length or production. Nutrient concentrations in fine roots in litter removal plots were lower than those in controls for nitrogen (N), calcium (Ca) and magnesium (Mg), concentrations in fine roots in litter addition plots were higher for N and Ca. Chronic litter removal has resulted in reduced forest growth due to lack of nutrients, probably nitrogen. Conversely, long-term litter addition has had fewer effects.
Data from: What controls variation in carbon use efficiency among Amazonian tropical forests?
Why do some forests produce biomass more efficiently than others? Variations in Carbon Use Efficiency (CUE: total Net Primary Production (NPP)/ Gross Primary Production (GPP)) may be due to changes in wood residence time (Biomass/NPPwood), temperature, or soil nutrient status. We tested these hypotheses in 14, one ha plots across Amazonian and Andean forests where we measured most key components of net primary production (NPP: wood, fine roots, and leaves) and autotrophic respiration (Ra; wood, rhizosphere, and leaf respiration). We found that lower fertility sites were less efficient at producing biomass and had higher rhizosphere respiration, indicating increased carbon allocation to belowground components. We then compared wood respiration to wood growth and rhizosphere respiration to fine root growth and found that forests with residence times <40 yrs had significantly lower maintenance respiration for both wood and fine roots than forests with residence times >40 yrs. A comparison of rhizosphere respiration to fine root growth showed that rhizosphere growth respiration was significantly greater at low fertility sites. Overall, we found that Amazonian forests produce biomass less efficiently in stands with residence times >40 yrs and in stands with lower fertility, but changes to long-term mean annual temperatures do not impact CUE.
Data from: Mapping tropical dry forest succession using multiple criteria spectral mixture analysis
Tropical dry forests (TDFs) in the Americas are considered the first frontier of economic development with less than 1% of their total original coverage under protection. Accordingly, accurate estimates of their spatial extent, fragmentation, and degree of regeneration are critical in evaluating the success of current conservation policies. This study focused on a well-protected secondary TDF in Santa Rosa National Park (SRNP) Environmental Monitoring Super Site, Guanacaste, Costa Rica. We used spectral signature analysis of TDF ecosystem succession (early, intermediate, and late successional stages), and its intrinsic variability, to propose a new multiple criteria spectral mixture analysis (MCSMA) method on the shortwave infrared (SWIR) of HyMap image. Unlike most existing iterative mixture analysis (IMA) techniques, MCSMA tries to extract and make use of representative endmembers with spectral and spatial information. MCSMA then considers three criteria that influence the comparative importance of different endmember combinations (endmember models): root mean square error (RMSE); spatial distance (SD); and fraction consistency (FC), to create an evaluation framework to select a best-fit model. The spectral analysis demonstrated that TDFs have a high spectral variability as a result of biomass variability. By adopting two search strategies, the unmixing results showed that our new MCSMA approach had a better performance in root mean square error (early: 0.160/0.159; intermediate: 0.322/0.321; and late: 0.239/0.235); mean absolute error (early: 0.132/0.128; intermediate: 0.254/0.251; and late: 0.191/0.188); and systematic error (early: 0.045/0.055; intermediate: −0.211/−0.214; and late: 0.161/0.160), compared to the multiple endmember spectral mixture analysis (MESMA). This study highlights the importance of SWIR in differentiating successional stages in TDFs. The proposed MCSMA provides a more flexible and generalized means for the best-fit model determination than common IMA methods.
Data from: Ants as ecological indicators of rainforest restoration: community convergence and the development of an Ant Forest Indicator Index in the Australian wet tropics
Ecosystem restoration can help reverse biodiversity loss, but whether faunal communities of forests undergoing restoration converge with those of primary forest over time remains contentious. There is a need to develop faunal indicators of restoration success that more comprehensively reflect changes in biodiversity and ecosystem function. Ants are an ecologically dominant faunal group and are widely advocated as ecological indicators. We examine ant species and functional group responses on a chronosequence of rainforest restoration in northern Australia, and develop a novel method for selecting and using indicator species. Four sampling techniques were used to survey ants at 48 sites, from grassland, through various ages (1–24 years) of restoration plantings, to mature forest. From principal components analysis of seven vegetation metrics, we derived a Forest Development Index (FDI) of vegetation change along the chronosequence. A novel Ant Forest Indicator Index (AFII), based on the occurrences of ten key indicator species associated with either grassland or mature forest, was used to assess ant community change with forest restoration. Grasslands and mature forests supported compositionally distinct ant communities at both species and functional levels. The AFII was strongly correlated with forest development (FDI). At forest restoration sites older than 5–10 years that had a relatively closed canopy, ant communities converged on those of mature rainforest, indicating a promising restoration trajectory for fauna as well as plants. Our findings reinforce the utility of ants as ecological indicators and emphasize the importance of restoration methods that achieve rapid closed-canopy conditions. The novel AFII assessed restoration status from diverse and patchily distributed species, closely tracking ant community succession using comprehensive species-level data. It has wide applicability for assessing forest restoration in a way that is relatively independent of sampling methodology and intensity, and without a need for new comparative data from reference sites.
Data from: Seed to seedling transitions in successional habitats across a tropical landscape
Recognition that tree recruitment depends on the balance between seed arrival and seedling survival has led to a surge of interest in seed-dispersal limitation and seedling-establishment limitation in primary forests. Virtually unaddressed are comparisons of this balance in mature and early successional habitats. We assessed seed rain and seedling recruitment dynamics of tree species in primary forest, secondary forest and pasture released from grazing in a tropical agricultural landscape. Seed to seedling ratios (seed effectiveness; Φi) for 43 species in southern Mexico determined differences in the extent to which seeds produced seedlings by habitat, life history, and dispersal mode. Reproductive potential as estimated by the transition from seed rain to seedling recruitment, differed by habitats, and varied dramatically by life history and dispersal mode. Expected recruit densities (Eit) were higher for animal-dispersed than wind-dispersed species, and for non-pioneer than pioneer species. Non-pioneers and animal-dispersed species had higher expected relative recruit abundance (εit) in primary forest (median of 4 seeds recruit−1) whereas in secondary forest wind-dispersed pioneers had the highest expected relative recruit abundance (median of 16 seeds per recruit). In pastures, wind-dispersed pioneer species were most successful with many more seeds per recruit (median of 291) than both forest habitats. Seeds per recruit (Φi) appeared to decrease with increase in seed mass for 43 species for which data were available (r = –0.55, P < 0.001). This was associated with a negative correlation of Φi with seed size in primary forest (r = –0.50, P = 0.08 for 13 species); Φi was not correlated with seed size in secondary forest (n = 16) or pasture (n = 14). Metrics of seeds per recruit, expected recruit density and expected relative recruit abundance dramatically illustrate differences in barriers to recruitment in successional habitats.
Data from: Dry-season decline in tree sapflux is correlated with leaf turgor loss point in a tropical rainforest
1. Water availability is a key determinant of forest ecosystem function and tree species distributions. While droughts are increasing in frequency in many ecosystems, including in the tropics, plant responses to water supply vary with species and drought intensity, and are therefore difficult to model. Based on physiological first principles, we hypothesized that trees with a lower turgor loss point (πtlp), i.e., a more negative leaf water potential at wilting, would maintain water transport for longer into a dry season. 2. We measured sapflux density of 22 mature trees of 10 species during a dry season in an Amazonian rainforest, quantified sapflux decline as soil water content decreased, and tested its relationship to tree πtlp, size, and leaf predawn and midday water potentials measured after the onset of the dry season. 3. The measured trees varied strongly in the response of water use to the seasonal drought, with sapflux at the end of the dry season ranging from 37 to 117% (on average 83 ± 5 %) of that at the beginning of the dry season. The decline of water transport as soil dried was correlated with tree πtlp (Spearman ρ≥0.63), but not with tree size or predawn and midday water potentials. Thus, trees with more drought-tolerant leaves better maintained water transport during the seasonal drought. 4. Our study provides an explicit correlation between a trait, measurable at the leaf level, and whole-plant performance under drying conditions. Physiological traits such as πtlp can be used to assess and model higher-scale processes in response to drying conditions.
Data from: Overlooked biodiversity loss in tropical smallholder agriculture
Smallholder agriculture is the main driver of deforestation in the western Amazon, where terrestrial biodiversity reaches its global maximum. Understanding the biodiversity value of the resulting mosaics of cultivations and secondary forest is therefore crucial for conservation planning. However, Amazonian communities are organized across multiple forest‐types that support distinct species assemblages, and little is known about smallholder impacts across the range of forest habitats that are essential for sustaining biodiversity. We address this issue with a large‐scale field inventory of birds and trees in primary forest and smallholder agriculture in northern Peru, spanning three key forest‐types that structure Amazonian biodiversity. For birds, smallholder agriculture supported species richness comparable to primary forest within each forest‐type, but biotic homogenization across forest‐types resulted in substantial losses of biodiversity overall. These overall losses are invisible to studies that focus solely on upland (terra firme) forest. For trees, biodiversity losses in upland forests dominated the signal across all habitats combined, and homogenization across habitats did not exacerbate biodiversity loss. Proximity to forest strongly predicted the persistence of forest‐associated bird and tree species in the smallholder mosaic, and because intact forest is ubiquitous in our study area, our results probably represent a best‐case scenario for biodiversity in Amazonian agriculture. Land‐use planning both inside and outside of protected areas should recognize that tropical smallholder agriculture has pervasive biodiversity impacts that are not apparent in typical single‐habitat studies. The full range of forest‐types must be surveyed to accurately assess biodiversity losses, and primary forests must be protected to prevent landscape‐scale biodiversity loss.
Data from: The activity of dung beetles increases foliar nutrient concentration in tropical seedlings
Dung beetles are extensively used as a focal taxon in tropical forests. Yet, information for most of their ecological functions comes from other systems. We present results from a field experiment in a tropical rainforest showing that dung beetle activity increases foliar phosphorus concentration in seedlings of the tree Brosimum lactescens. Our results open new lines of research to assess the multiple effects that dung beetles may have on rainforest plants.
Supplemental information, code, and data for the MS: Defaunation impacts carbon storage in tropical forests.
<p># MS_Carbon<br /> Supplemental information, code, and data for the MS: <br /> Carolina Bello, Mauro Galetti, Marco A. Pizo, Luiz Fernando S. Magnago, Mariana Ferreira Rocha, Renato A. F. Lima, Carlos A. Peres, Otso Ovaskainen, and Pedro Jordano (2015). Defaunation impacts carbon storage in tropical forests.</p> <p> </p> <p>*Summary*:<br /> Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation and climate change have significant impacts on tropical carbon stocks, however an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, yet many of these frugivores are threatened by hunting, illegal trade and habitat loss. We used a large dataset on tree species composition and abundance, seed, fruit and carbon related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores at 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion (10%) of large-seeded trees are extirpated.</p> <p> </p>
FIGURE 2 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 2. Amazopimpla errabunda Sääksjärvi, Gauld & Jussila, sp.n. Mesosoma, anterior part of metasoma and hind leg, showing colour pattern (Holotype female).
FIGURE 6 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 6. Amazopimpla errabunda Sääksjärvi, Gauld & Jussila, sp.n. The tip of the ovipositor (Holotype female).
FIGURE 9 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 9. Amazopimpla lutea Palacio, Sääksjärvi, Gauld & Jussila, sp.n. The tip of the ovipositor (Paratype female).
FIGURE 8 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 8. Amazopimpla guayanaensis Sääksjärvi, Gauld & Jussila, sp.n. The tip of the ovipositor (Holotype female).
FIGURE 3 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 3. Amazopimpla farallonensis Palacio, sp.n. Mesosoma, anterior part of metasoma and hind leg, showing colour pattern (Holotype female).
FIGURE 3 in New phytoseiid mites (Acari: Phytoseiidae) from tropical Africa
FIGURE 3. Typhlodromips extrasetus Moraes, Oliveira & Zannou, n. sp.: A. Female dorsal shield; B. Female ventral surface; C. Spermatheca; D. Female leg IV; E. Spermatodactyl; F. Male ventrianal shield.
FIGURE 5 in New phytoseiid mites (Acari: Phytoseiidae) from tropical Africa
FIGURE 5. Typhlodromus (Anthoseius) cephalochaitosus Moraes, Oliveira & Zannou, n. sp. (female): A. Dorsal shield; B. Ventral surface; C. Chelicera; D. Spermatheca; E. Leg IV.
FIGURE 4 in New phytoseiid mites (Acari: Phytoseiidae) from tropical Africa
FIGURE 4. Australiseiulus laterisetus Moraes, Oliveira & Zannou, n. sp. (female): A. Dorsal shield; B. Ventral surface; C. Spermatheca; D. Leg IV.
FIGURE 2 in New phytoseiid mites (Acari: Phytoseiidae) from tropical Africa
FIGURE 2. Typhlodromips occidentafricanus Moraes, Oliveira & Zannou, n. sp. (female): A. Dorsal shield; B. Ventral surface; C. Spermatheca; D. Leg IV.
FIGURE 1 in New phytoseiid mites (Acari: Phytoseiidae) from tropical Africa
FIGURE 1. Typhlodromalus breviscutus Moraes, Oliveira & Zannou, n. sp. (female): A. Dorsal shield; B. Ventral surface; C. Chelicera; D. Spermatheca; E. Leg IV.
FIGURE 2. Saltipedis navassensis n in Saltipedis navassensis, a new species of apseudomorph tanaidacean (Crustacea: Peracarida: Parapseudidae) from the tropical northwestern Atlantic
FIGURE 2. Saltipedis navassensis n. sp. A, female maxilliped, with enlargment of inner endite showing coupling hooks. B, male cheliped with enlargement of propodus and dactylus. C, articulation of male cheliped (diagrammatic showing groove in basis to accommodate carpus). D, female cheliped. Scale bar: B,C = 0.25 mm; A,D = 0.1 mm
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.