共查询到20条相似文献,搜索用时 15 毫秒
1.
Christopher J. Lortie Eva Gruber Alex Filazzola Taylor Noble Michael Westphal 《Ecology and evolution》2018,8(1):706-715
Deserts are increasing in extent globally, but existing deserts are decreasing in health. The basic biology and ecology of foundation plant species in deserts are limited. This is a direct study that provides an estimate of the capacity for a locally dominant foundation shrub species in California to recover from damage. Desert shrubs are cleared and damaged by humans for many purposes including agriculture, oil and gas production, and sustainable energy developments; we need to know whether foundation species consistently facilitate the abundance and diversity of other plants in high‐stress ecosystems and whether they can recover. A total of 20 Ephedra californica shrubs were clipped to the ground at a single site and systematically resampled for regrowth 2 years later. These shrubs were damaged once and regrew rapidly, and relatively, larger shrubs were not more resilient. This study provides evidence for what we termed the “Groot Effect” because smaller individuals of this shrub species can recover from significant aboveground damage and continue to have positive effects on other plant species (similar to the popular culture reference to a benefactor tree species). The density of other plant species was consistently facilitated while effects on diversity varied with season. These findings confirm that E. californica is a foundation species that can be an important restoration tool within the deserts of California in spite of extreme cycles of drought and physical damage to its canopy. 相似文献
2.
Sonia Kéfi;C J. Lortie;Lohengrin A. Cavieres; 《Oikos》2024,2024(8):e10984
Global change is a multifaceted, unprecedented crisis hitting the life support system of our planet. Among global changes, climate change is regarded as one of the most grave threats to biodiversity because of its direct impacts on species and ecosystems integrity and because of its indirect consequences through synergistic effects with other global change factors such as biological invasions. The challenges presented to either reduce or mitigate this biodiversity crisis derived from climate change require novel synthesis and innovation in ecological and evolutionary theory. Positive species interactions within and between trophic levels can play a key role in the resilience of ecological communities. Depending on the tolerance of nurse species to different aspects of climate change, communities can be more or less resilient to those changes. This knowledge has important implications for both natural communities and agroecosystems. Further, our fundamental understanding of the role of positive interactions can also enable both effective conservation and restoration levers in space and time. 相似文献
3.
Mei Li Zhong Wei Jianing Wang Alexandre Jousset Ville‐Petri Friman Yangchun Xu Qirong Shen Thomas Pommier 《Ecology letters》2019,22(1):149-158
While several studies have established a positive correlation between community diversity and invasion resistance, it is less clear how species interactions within resident communities shape this process. Here, we experimentally tested how antagonistic and facilitative pairwise interactions within resident model microbial communities predict invasion by the plant–pathogenic bacterium Ralstonia solanacearum. We found that facilitative resident community interactions promoted and antagonistic interactions suppressed invasions both in the lab and in the tomato plant rhizosphere. Crucially, pairwise interactions reliably explained observed invasion outcomes also in multispecies communities, and mechanistically, this was linked to direct inhibition of the invader by antagonistic communities (antibiosis), and to a lesser degree by resource competition between members of the resident community and the invader. Together, our findings suggest that the type and strength of pairwise interactions can reliably predict the outcome of invasions in more complex multispecies communities. 相似文献
4.
- Plant facilitation promotes coexistence by maintaining differences in the regeneration niche because some nurse species recruit under arid conditions, whereas facilitated species recruit under more mesic conditions. In one Mexican community, 95% of species recruit through facilitation; Mimosa luisana being a keystone nurse for many of them. M. luisana individuals manifest greater fitness when growing in association with their facilitated plants than when growing in isolation. This observation suggests that nurses also benefit from their facilitated plants, a benefit thought to be mediated by mycorrhizal fungi.
- Under field conditions, we experimentally tested whether mycorrhizal fungi mediate the increased fitness that M. luisana experiences when growing in association with its facilitated plants. We applied fungicide to the soil for nurse plants growing alone and growing in association with their facilitated plants in order to reduce the mycorrhizal colonisation of roots. We then assessed the quantity and quality of seed production of M. luisana in four treatments (isolated‐control, isolated‐fungicide, associated‐control and associated‐fungicide).
- Fungicide application reduced the percentage root length colonised by mycorrhizae and reduced fitness of M. luisana when growing in association with their facilitated plants but not when growing in isolation. This reduction was reflected in the total number of seeds, number of seeds per pod, seed mass and seed viability.
- These results suggest that nurses benefit from the presence of their facilitated plants through links established by mycorrhizae, indicating that both plants and belowground mutualistic communities are all part of one system, coexisting by means of intrinsically linked interactions.
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Multi‐species mixed plantations can be designed to meet social, economic, and environmental objectives during forest restoration. This paper reports results from an experiment in southern Sweden concerning the influence of three different fast growing nurse tree species on the cover of herbaceous vegetation and on the performance of several target tree species. After 10 years, the nurse trees had reduced the competing herbaceous vegetation but the effect was weak and it may take more than a decade to achieve effective vegetation control. The nurse tree species Betula pendula and Larix x eurolepis did improve stem form in some target tree species, but had a minor effect on survival and growth. The open conditions before crown closure of nurse trees strongly influence seedling performance and so delayed planting of target tree species may provide a means to avoid those conditions. Survival and growth differed greatly among the tree species. Besides the two nurse tree species mentioned above, high survival was found in Picea abies and Quercus robur and intermediate survival in Fagus sylvatica, Tilia cordata, and in the N‐fixing nurse tree Alnus glutinosa. Survival was low in the target tree species Fraxinus excelsior L. and Prunus avium. For restoration practitioners, our results illustrate the potential of using nurse trees for rapidly building a new forest structure and simultaneously increase productivity, which might be a cost‐effective strategy for forest restoration. 相似文献
8.
Dylan R. Kent Joshua S. Lynn Steven C. Pennings Lara A. Souza Melinda D. Smith Jennifer A. Rudgers 《Ecology and evolution》2020,10(13):6385-6394
Patterns of insect herbivory may follow predictable geographical gradients, with greater herbivory at low latitudes. However, biogeographic studies of insect herbivory often do not account for multiple abiotic factors (e.g., precipitation and soil nutrients) that could underlie gradients. We tested for latitudinal clines in insect herbivory as well as climatic, edaphic, and trait‐based drivers of herbivory. We quantified herbivory on five dominant grass species over 23 sites across the Great Plains, USA. We examined the importance of climate, edaphic factors, and traits as correlates of herbivory. Herbivory increased at low latitudes when all grass species were analyzed together and for two grass species individually, while two other grasses trended in this direction. Higher precipitation was related to more herbivory for two species but less herbivory for a different species, while higher specific root length was related to more herbivory for one species and less herbivory for a different species. Taken together, results highlight that climate and trait‐based correlates of herbivory can be highly contextual and species‐specific. Patterns of insect herbivory on dominant grasses support the hypothesis that herbivory increases toward lower latitudes, though weakly, and indicates that climate change may have species‐specific effects on plant–herbivore interactions. 相似文献
9.
Jacob E. Lucero Merav Seifan Ragan M. Callaway Christopher J. Lortie 《Diversity & distributions》2020,26(9):1177-1197
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Xi Shan Kevin H. Gardner D.R. Muhandiram Lewis E. Kay Cheryl H. Arrowsmith 《Journal of biomolecular NMR》1998,11(3):307-318
Deuterium decoupled, triple resonance NMR spectroscopy was used to analyze complexes of 2H,15N,13C labelled intact and (des2–7) trp repressor (2–7 trpR) from E. coli bound in tandem to an idealized 22 basepair trp operator DNA fragment and the corepressor 5-methyltryptophan. The DNA sequence used here binds two trpR dimers in tandem resulting in chemically nonequivalent environments for the two subunits of each dimer. Sequence- and subunit-specific NMR resonance assignments were made for backbone 1HN, 15N, 13C positions in both forms of the protein and for13 C in the intact repressor. The differences in backbone chemical shifts between the two subunits within each dimer of 2–7 trpR reflect dimer-dimer contacts involving the helix-turn-helix domains and N-terminal residues consistent with a previously determined crystal structure [Lawson and Carey (1993) Nature, 366, 178–182]. Comparison of the backbone chemical shifts of DNA-bound 2–7 trpR with those of DNA-bound intact trpR reveals significant changes for those residues involved in N-terminal-mediated interactions observed in the crystal structure. In addition, our solution NMR data contain three sets of resonances for residues 2–12 in intact trpR suggesting that the N-terminus has multiple conformations in the tandem complex. Analysis of C chemical shifts using a chemical shift index (CSI) modified for deuterium isotope effects has allowed a comparison of the secondary structure of intact and 2–7 tprR. Overall these data demonstrate that NMR backbone chemical shift data can be readily used to study specific structural details of large protein complexes. 相似文献
12.
1. When herbivores of distinct feeding guilds, such as phloem feeders and leaf chewers, interact, the outcome of these interactions often shows facilitation. However, whether this facilitation turns into competition at stronger herbivory pressure remains unknown. 2. Using an integrative approach that links ecological processes (behavioural choices of insects) with physiological plant mechanisms (nutrient and phytohormone levels) for the wild crucifer Brassica nigra (L.) Koch., this study evaluates preferences of leaf chewers for plants previously infested with several densities of the specialist aphid Brevicoryne brassicae L. (Hemiptera, Aphididae). As leaf chewers, four species of caterpillars (Lepidoptera) were selected that differ in their degree of specialisation in crucifers. 3. These results show that, whereas at low and medium aphid densities caterpillars displayed a preference for aphid‐infested plants or no preference, at high aphid infestation density, all four species of caterpillar preferred uninfested plants, with a significant difference for Pieris rapae and Mamestra brassicae. 4. In contrast to our expectation, the consistent preference for uninfested plants at a high aphid density could not be associated with a decrease in plant nutrition. However, while jasmonate concentrations [i.e. 12‐oxo‐phytodienoic acid and jasmonic acid (JA)] at medium aphid‐density infestation decreased compared with low levels of infestation, at high infestation level, the jasmonates JA as well as JA conjugated with the amino acid isoleucine were present at higher levels compared with low‐infestation treatments. 5. This work provides evidence that positive interactions observed in herbivore communities can be transient, leading to negative interactions mediated by changes in plant defences rather than in plant nutrition. 相似文献
13.
The majority of terrestrial plants form mutualistic associations with arbuscular mycorrhizal fungi (AMF) and rhizobia (i.e., nitrogen‐fixing bacteria). Understanding these associations has important implications for ecological theory and for restoration practice. Here, we tested whether the presence of AMF and rhizobia influences the performance of native woody plants invaded by a non‐native grass in experimental microcosms. We planted eight plant species (i.e., Acacia acuminata, A. microbotrya, Eucalyptus loxophleba subsp. loxophleba, E. astringens, Calothamnus quadrifidus, Callistemon phoeniceus, Hakea lissocarpha and H. prostrata) in microcosms of field‐conditioned soil with and without addition of AMF and rhizobia in a fully factorial experimental design. After seedling establishment, we seeded half the microcosms with an invasive grass Bromus diandrus. We measured shoot and root biomass of native plants and Bromus, and on roots, the percentage colonization by AMF, number of rhizobia‐forming nodules and number of proteaceous root clusters. We found no effect of plant root symbionts or Bromus addition on performance of myrtaceous, and as predicted, proteaceous species as they rely little or not at all on AMF and rhizobia. Soil treatments with AMF and rhizobia had a strong positive effect (i.e., larger biomass) on native legumes (A. microbotrya and A. acuminata). However, the beneficial effect of root symbionts on legumes became negative (i.e., lower biomass and less nodules) if Bromus was present, especially for one legume, i.e., A. acuminata, suggesting a disruptive effect of the invader on the mutualism. We also found a stimulating effect of Bromus on root nodule production in A. microbotrya and AMF colonization in A. acuminata which could be indicative of legumes’ increased resource acquisition requirement, i.e., for nitrogen and phosphorus, respectively, in response to the Bromus addition. We have demonstrated the importance of measuring belowground effects because the aboveground effects gave limited indication of the effects occurring belowground. 相似文献
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Julio M. Alcntara Jos L. Garrido Alicia Montesinos‐Navarro Pedro J. Rey Alfonso Valiente‐Banuet Miguel Verdú 《植被学杂志》2019,30(6):1239-1249
Ecological network studies are providing important advances about the organization, stability and dynamics of ecological systems. However, the ecological networks approach is being integrated very slowly in plant community ecology, even though the first studies on plant facilitation networks (FNs) were published more than a decade ago. The study of interaction networks between established plants and plants recruiting beneath them, which we call Recruitment Networks (RNs), can provide new insights on mechanisms driving plant community structure and dynamics. RNs basically describe which plants recruit under which others, so they can be seen as a generalisation of the classic FNs since they do not imply any particular effect (positive, negative or neutral) of the established plants on recruiting ones. RNs summarise information on the structure of sapling banks. More importantly, the information included in RNs can be incorporated into models of replacement dynamics to evaluate how different aspects of network structure, or different mechanisms of network assembly, may affect plant community stability and species coexistence. To allow an efficient development of the study of FNs and RNs, here we unify concepts, synthesise current knowledge, clarify some conceptual issues, and propose basic methodological guidelines to standardise sampling methods that could make future studies of these networks directly comparable. 相似文献
15.
The invasive erect prickly pear cactus (Opuntia stricta) has reduced rangeland quality and altered plant communities throughout much of the globe. In central Kenya's Laikipia County, olive baboons (Papio anubis) frequently consume O. stricta fruits and subsequently disperse the seeds via defecation. Animal‐mediated seed dispersal can increase germination and subsequent survival of plants. However, consumption of seeds (seed predation) by rodents may offset the potential benefits of seed dispersal for cactus establishment by reducing the number of viable seeds. We investigated foraging preferences of a common and widely distributed small mammal—the fringe‐tailed gerbil (Gerbilliscus robustus), between O. stricta seeds deposited in baboon faeces versus control O. stricta seeds. In addition to providing evidence of seed predation on O. stricta by G. robustus, our data show that seed removal was higher (shorter time to use) for seeds within faeces than for control seeds. G. robustus clearly prefers seeds within faeces compared to control seeds. These results suggest that high abundances of rodents may limit successful establishment of O. stricta seeds, possibly disrupting seed dispersal via endozoochory by baboons. 相似文献
16.
Maowei Liang Jiquan Chen Elise S. Gornish Xue Bai Zhiyong Li Cunzhu Liang 《Ecology and evolution》2018,8(16):8187-8196
Grazing effects on arid and semi‐arid grasslands can be constrained by aridity. Plant functional groups (PFGs) are the most basic component of community structure (CS) and biodiversity & ecosystem function (BEF). They have been suggested as identity‐dependent in quantifying the response to grazing intensity and drought severity. Here, we examine how the relationships among PFGs, CS, BEF, and grazing intensity are driven by climatic drought. We conducted a manipulative experiment with three grazing intensities in 2012 (nondrought year) and 2013 (drought year). We classified 62 herbaceous plants into four functional groups based on their life forms. We used the relative species abundance of PFGs to quantify the effects of grazing and drought, and to explore the mechanisms for the pathway correlations using structural equation models (SEM) among PFGs, CS, and BEF directly or indirectly. Grazers consistently favored the perennial forbs (e.g., palatable or nutritious plants), decreasing the plants’ relative abundance by 23%–38%. Drought decreased the relative abundance of ephemeral plants by 42 ± 13%; and increased perennial forbs by 20 ± 7% and graminoids by 80 ± 31%. SEM confirmed that annuals and biennials had negative correlations with the other three PFGs, with perennial bunchgrasses facilitated by perennial rhizome grass. Moreover, the contributions of grazing to community structure (i.e., canopy height) were 1.6–6.1 times those from drought, whereas drought effect on community species richness was 3.6 times of the grazing treatment. Lastly, the interactive effects of grazing and drought on BEF were greater than either alone; particularly, drought escalated grazing damage on primary production. Synthesis. The responses of PFGs, CS, and BEF to grazing and drought were identity‐dependent, suggesting that grazing and drought regulation of plant functional groups might be a way to shape ecosystem structure and function in grasslands. 相似文献
17.
VIVIAN O. LIMA PETERSON R. DEMITE CAMILA VIEIRA REINALDO J. F. FERES GUSTAVO Q. ROMERO 《Ecological Entomology》2013,38(2):193-200
- Ecosystem engineers are organisms that change the physical structure of environments and provide habitats for other organisms. Lepidopteran caterpillars may act as ecosystem engineers by rolling leaves as shelters to complete metamorphosis. After being abandoned, these structures may provide shelter for other organisms. In this study, the influence of leaf‐rolling caterpillars on tropical mite communities was reported.
- Expanded leaves and leaves rolled by larvae and also developed field experiments using leaves rolled manually with different shapes and sizes (i.e. different architectures) in different seasons were surveyed (dry and rainy).
- While the abundance and diversity of predatory mites were higher in rolled leaves, the abundance of phytophages decreased in these leaves. Species composition differed between rolled and expanded leaves. The structure of shelters affected the distribution of predatory mites, with higher abundances found on funnel‐shaped leaves. Predatory mites only benefited from the rolled leaves in the dry season.
- This is the first study showing (i) the contrasting effects of ecosystem engineers on microarthropod communities, favouring some feeding guilds and inhibiting others; (ii) that the shape of rolled leaves has variable effects on mite communities; and (iii) that facilitation was temporally dependent, i.e. occurred only in the dry season.
18.
Does Invasion of Exotic Plants Promote Invasion of Exotic Flower Visitors? A Case Study from the Temperate Forests of the Southern Andes 总被引:2,自引:0,他引:2
Habitat disturbance, particularly of human origin, promotes the invasion of exotic plants, which in turn might foster the invasion of alien-interacting animals. Here we assess whether the invasion of exotic plants – mostly mediated by habitat disturbance – facilitates the invasion of exotic flower visitors in temperate forests of the southern Andes, Argentina. We recorded visit frequencies and the identity of visitors to the flowers of 15 native and 15 exotic plant species occurring in different highly disturbed and less disturbed habitats. We identified three alien flower visitors, the hymenopterans Apis mellifera, Bombus ruderatus, and Vespula germanica. We found significantly more visitation by exotic insects in disturbed habitats. This pattern was explained, at least in part, by the association between alien flower visitors and flowers of exotic plants, which occurred more frequently in disturbed habitats. However, this general pattern masked different responses between the two main alien flower visitors. Apis mellifera exploited almost exclusively the flowers of a subset of herbaceous exotic plants that thrive under disturbance, whereas B. ruderatus visited equally flowers of both exotic and native plants in both disturbed and undisturbed habitats. We did not find any strong evidence that flowers of exotic plants were more generalist than those of native plants, or that exotic flower visitors were more generalist than their native counterparts. Our results suggest that alien plant species could facilitate the invasion of at least some exotic flower visitors to disturbed habitats. Because flowering plants as well as flower visitors benefit from this mutualism, this association may enhance, through a positive feedback, successful establishment of both exotic partners. 相似文献
19.
Uttamkumar Samanta Debnath Pal Pinak Chakrabarti 《Acta Crystallographica. Section D, Structural Biology》1999,55(8):1421-1427
The geometry of the interaction of the aromatic side chains of phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp) and histidine (His) with the indole ring of Trp has been analyzed using the structures in the Protein Data Bank in order to understand the dependence of the packing behaviour on the size and chemical nature of the aromatic rings. The Phe ring prefers to interact either perpendicularly, with its edge pointing towards the Trp face, or in an offset-stacked arrangement. The edge-to-face motif is typical of a Trp–Trp pair. While parallel stacking is the dominant feature of Trp–His interaction, Tyr packs in a more uniform manner around Trp with a higher than expected occurrence at the edge and a few cases of possible OH–π interaction. 相似文献
20.
Maristella De Cicco Lech‐G. Milroy Sonja A. Dames 《Protein science : a publication of the Protein Society》2018,27(2):546-560
Increased efforts have been undertaken to better understand the formation of signaling complexes at cellular membranes. Since the preparation of proteins containing a transmembrane domain or a prenylation motif is generally challenging an alternative membrane anchoring unit that is easy to attach, water‐soluble and binds to different membrane mimetics would find broad application. The 33‐residue long FATC domain of yeast TOR1 (y1fatc) fulfills these criteria and binds to neutral and negatively charged micelles, bicelles, and liposomes. As a case study, we fused it to the FKBP506‐binding region of the protein FKBP38 (FKBP38‐BD) and used 1H–15N NMR spectroscopy to characterize localization of the chimeric protein to micelles, bicelles, and liposomes. Based on these and published data for y1fatc, its use as a C‐terminally attachable membrane anchor for other proteins is compatible with a wide range of buffer conditions (pH circa 6–8.5, NaCl 0 to >150 mM, presence of reducing agents, different salts such as MgCl2 and CaCl2). The high water‐solubility of y1fatc enables its use for titration experiments against a membrane‐localized interaction partner of the fused target protein. Results from studies with peptides corresponding to the C‐terminal 17–11 residues of the 33‐residue long domain by 1D 1H NMR and CD spectroscopy indicate that they still can interact with membrane mimetics. Thus, they may be used as membrane anchors if the full y1fatc sequence is disturbing or if a chemically synthesized y1fatc peptide shall be attached by native chemical ligation, for example, unlabeled peptide to 15N‐labeled target protein for NMR studies. 相似文献