Find research datasets worth reusing

Search datasets from major research repositories and use ShareScore to quickly assess how well each record supports discovery, access, and reuse.

106

datasets available to search

ShareScore release 0.9.0

Dataset results

106 results for “encroachment”

Learn how ShareScore rates datasets ↗

dryad32/100

Facilitation by isolated trees triggers woody encroachment and a biome shift at the savanna-forest transition

1. Woody encroachment into grassy biomes is a global phenomenon, often resulting in a nearly complete turnover of species, with savanna specialists being replaced by forest-adapted species. Understanding the mechanisms involved in this change is important for devising strategies for managing savannas. 2. We examined how isolated trees favor woody encroachment and species turnover by overcoming dispersal limitation and environmental filtering. In a savanna released from fire in southeastern Brazil (Cerrado) we sampled woody plants establishing under 40 tree canopies and in paired treeless plots. These trees comprised eight species selected for habitat preference (savanna or forest) and dispersal syndrome (bird-dispersed or not). We recorded dimensions of each tree, dispersal syndrome and habitat preference of recruits, and quantified the physical environment within each plot, aiming at a mechanistic understanding of woody encroachment. 3. We found clear evidence that isolated trees cause nucleation and drive changes in functional composition of savanna. Effectiveness as nucleator differed among species, but was unrelated to their functional guilds (habitat preference or dispersal syndrome). Density of saplings in nuclei was partially explained by soil moisture (+), daily temperature amplitude (-), and sum of bases (-). 4. Our results indicate that isolated trees act first as perches, strongly favoring bird-dispersed species. They then act as nurse trees, considerably changing the environment in favor of forest-adapted recruits. In the long term, as the nuclei expand and merge, savanna specialists tend to disappear and the savanna turns into a low-diversity forest. 5. Synthesis and applications: Fire suppression has allowed the nucleation process and consequently the woody encroachment and fast replacement of savanna specialists by forest species in the Cerrado. By elucidating the mechanisms behind woody encroachment, we recommend using prescribed fires to burn forest seedlings and to reduce tree canopy size wherever the management goal is to maintain the typical savanna structure and composition.

opencc-zeroAug 2021View details →

dryad32/100

High-intensity fires may have limited medium-term effectiveness for reversing woody plant encroachment in an African savanna

1. Woody thickening or "bush encroachment" is a growing concern in savannas worldwide and can reportedly be reversed by applying high-intensity fires. Preliminary findings following experimental fires in 2010 and 2013 indicated that woody plant cover declined one year after high-intensity fires, but increased after low-intensity fires. However, the longer-term outcomes of high-intensity fires are largely unknown. 2. To establish longer-term outcomes, we re-assessed sites subjected to Low, Medium and High-intensity fire treatments 10 years after the initial experimental fires. We compared woody vegetation structure in 2010 with that in 2020 using both ground surveys and airborne LiDAR. 3. Ground surveys revealed increases in the number of stems and individual shrubs (< 10 m tall) over 10 years, and decreases in shrub height, with no significant differences between treatments. Large trees (≥ 10 m) declined by about 65% in number due to ongoing high mortality across treatments over 10 years. 4. LiDAR surveys revealed significant but very small differences in woody plant height and cover between treatments after 10 years. Median height was around 2 m in all treatments, and 90th percentile tree height was moderately taller in the Low fire treatment. Mean canopy cover was about 55% in all treatments. The treatments, therefore, did not result in a meaningful reversal of woody encroachment with no discernible difference between the treatment sites after 10 years. 5. Synthesis and applications. The application of high-intensity fires did not reverse woody encroachment in the longer term. In addition, the application of such treatments would be impractical at a large scale. Within a framework of Strategic Adaptive Management, the next logical step would be to attempt a different approach. In this case, it is intended to use early or late wet season burns to increase the mortality of shrubs when they are in a more vulnerable phenological state. This study illustrates the importance of ongoing long-term monitoring, review and adaptation for finding practical ways to achieve desired ecological outcomes.

opencc-zeroJan 2023View details →

dryad32/100

Woodland wildfire enables fungal colonization of encroaching Douglas-fir

<ol> <li>Self-reinforcing differences in fire frequency help closed-canopy forests, which resist fire, and open woodlands, which naturally burn often, to co-occur stably at landscape scales. Forest tree seedlings, which could otherwise encroach and overgrow woodlands, are killed by regular fire, yet fire has other effects that may also influence these feedbacks. In particular, many forest trees require symbiotic ectomycorrhizal fungi in order to establish. By restructuring soil fungal communities, fire might affect the availability of symbionts or the potential for symbiont sharing between encroaching trees and woodland vegetation.</li> <li>To investigate this possibility, we performed a soil bioassay experiment using inoculum from burned and unburned oak woodlands and Douglas-fir forests. We examined how fire, ecosystem type, and neighboring heterospecific seedlings affect fungal root community assembly of Douglas-firs and oaks. We asked whether heterospecific seedlings facilitated fungal colonization of seedling roots in non-native soil, and if so, whether fire influenced this interaction.</li> <li>External fungal colonization of oak roots was more influenced by fire and ecosystem type than by the presence of a Douglas-fir, and oaks increased the likelihood that Douglas-fir roots would be colonized by fungi in oak woodland soil. Yet fire increased colonization of Douglas-fir in oak soil, diminishing the otherwise crucial role played by oak facilitation. Fire also strengthened the positive effect of Douglas-firs on oak root-associated fungal diversity in Douglas-fir forest soil.</li> <li>Prior work shows that fire supports woodland ecosystems by stemming recruitment of encroaching seedlings. Here, we find evidence that it may contrastingly reduce fungal limitation of invasive seedling growth and establishment, otherwise relieved only by facilitation. Future work can investigate how these opposing effects might contribute to the net impact of changes in fire regime on landcover stability.</li> </ol>

opencc-zeroMay 2023View details →

zenodo32/100

Dataset for the article "Alnus viridis: an encroaching species with valuable nutritional value reducing livestock greenhouse gas emissions"

Both files provide the data used for the article "Alnus viridis: an encroaching species with valuable nutritional value reducing livestock greenhouse gas emissions"   <ol> <li>"Data_file_1" provides the measured components of A. viridis, i.e. the chemical composition (micro/macro-elements, fibre fractions, ash), the phenolic content and the functional traits. </li> <li>"Data_file_2" provides the results of the in vitro measurements on organic matter digestibility and gas production.</li> </ol>

opencc-by-4.0Jun 2023View details →

zenodo32/100

Nitrogen translocation by Highland cattle grazing in Alnus viridis‑encroached pastures

Dataset detailing the N excreted, N ingested and N fluxes in vegetation patches for the article "Nitrogen translocation by Highland cattle grazing in Alnus viridis‑encroached pastures"

opencc-by-4.0Mar 2023View details →

dryad32/100