共查询到10条相似文献,搜索用时 140 毫秒
1.
ANITA ANTONINKA JULIE E. WOLF MATTHEW BOWKER AIMÉE T. CLASSEN NANCY COLLINS JOHNSON 《Global Change Biology》2009,15(4):914-929
Cryptic belowground organisms are difficult to observe and their responses to global changes are not well understood. Nevertheless, there is reason to believe that interactions among above- and belowground communities may mediate ecosystem responses to global change. We used grassland mesocosms to manipulate the abundance of one important group of soil organisms, arbuscular mycorrhizal (AM) fungi, and to study community and ecosystem responses to CO2 and N enrichment. Responses of plants, AM fungi, phospholipid fatty acids and community-level physiological profiles were measured after two growing seasons. Ecosystem responses were examined by measuring net primary production (NPP), evapotranspiration, total soil organic matter (SOM), and extractable mineral N. Structural equation modeling was used to examine the causal relationships among treatments and response variables. We found that while CO2 and N tended to directly impact ecosystem functions (evapotranspiration and NPP, respectively), AM fungi indirectly impacted ecosystem functions by influencing the community composition of plants and other root fungi, soil fungi and soil bacteria. We found that the mycotrophic status of the dominant plant species in the mesocosms determined whether the presence of AM fungi increased or decreased NPP. Mycotrophic grasses dominated the mesocosm communities during the first growing season, and the mycorrhizal treatments had the highest NPP. In contrast, nonmycotrophic forbs were dominant during the second growing season and the mycorrhizal treatments had the lowest NPP. The composition of the plant community strongly influenced soil N, and the community composition of soil organisms strongly influenced SOM accumulation in the mesocosms. These results show how linkages between above- and belowground communities can determine ecosystem responses to global change. 相似文献
2.
土壤线虫对气候变化的响应研究进展 总被引:2,自引:0,他引:2
全球变化对陆地生态系统功能具有重要而深远的影响。陆地生态系统地下部分具有重要的生态功能,其组成及结构对气候变化的响应将进一步减缓或加剧全球化进程。土壤线虫在各类生态系统中分布十分广泛,是地下食物网的重要组分,在维持土壤生物多样性及营养物质循环过程中发挥重要作用,其组成及结构对不同气候变化驱动因子的响应机制与模式不尽相同。增温及降水格局变化主要是通过改变线虫生境而直接影响其种群密度与结构,两者通常表现为正效应且作用效果随处理时间的延长而增强。CO2与大气氮沉降主要是通过影响地上植被,凋落物质量,土壤理化性质等间接过程影响土壤线虫。同时,不同的全球变化因子之间存在着复杂的交互作用,深入理解这些因子之间交互作用对线虫群落的影响模式与机制对于探讨未来气候变化情景下生态统生物多样性及养分循环过程具有重要的理论指导意义。 相似文献
3.
Changes in biocrust cover drive carbon cycle responses to climate change in drylands 总被引:2,自引:0,他引:2
Fernando T. Maestre Cristina Escolar Mónica Ladrón de Guevara José L. Quero Roberto Lázaro Manuel Delgado‐Baquerizo Victoria Ochoa Miguel Berdugo Beatriz Gozalo Antonio Gallardo 《Global Change Biology》2013,19(12):3835-3847
Dryland ecosystems account for ca. 27% of global soil organic carbon (C) reserves, yet it is largely unknown how climate change will impact C cycling and storage in these areas. In drylands, soil C concentrates at the surface, making it particularly sensitive to the activity of organisms inhabiting the soil uppermost levels, such as communities dominated by lichens, mosses, bacteria and fungi (biocrusts). We conducted a full factorial warming and rainfall exclusion experiment at two semiarid sites in Spain to show how an average increase of air temperature of 2–3 °C promoted a drastic reduction in biocrust cover (ca. 44% in 4 years). Warming significantly increased soil CO2 efflux, and reduced soil net CO2 uptake, in biocrust‐dominated microsites. Losses of biocrust cover with warming through time were paralleled by increases in recalcitrant C sources, such as aromatic compounds, and in the abundance of fungi relative to bacteria. The dramatic reduction in biocrust cover with warming will lessen the capacity of drylands to sequester atmospheric CO2. This decrease may act synergistically with other warming‐induced effects, such as the increase in soil CO2 efflux and the changes in microbial communities to alter C cycling in drylands, and to reduce soil C stocks in the mid to long term. 相似文献
4.
Climate change and plant regeneration from seed 总被引:2,自引:0,他引:2
JEFFREY L. WALCK SITI N. HIDAYATI KINGSLEY W. DIXON KEN THOMPSON PETER POSCHLOD 《Global Change Biology》2011,17(6):2145-2161
At the core of plant regeneration, temperature and water supply are critical drivers for seed dormancy (initiation, break) and germination. Hence, global climate change is altering these environmental cues and will preclude, delay, or enhance regeneration from seeds, as already documented in some cases. Along with compromised seedling emergence and vigour, shifts in germination phenology will influence population dynamics, and thus, species composition and diversity of communities. Altered seed maturation (including consequences for dispersal) and seed mass will have ramifications on life history traits of plants. Predicted changes in temperature and precipitation, and thus in soil moisture, will affect many components of seed persistence in soil, e.g. seed longevity, dormancy release and germination, and soil pathogen activity. More/less equitable climate will alter geographic distribution for species, but restricted migratory capacity in some will greatly limit their response. Seed traits for weedy species could evolve relatively quickly to keep pace with climate change enhancing their negative environmental and economic impact. Thus, increased research in understudied ecosystems, on key issues related to seed ecology, and on evolution of seed traits in nonweedy species is needed to more fully comprehend and plan for plant responses to global warming. 相似文献
5.
Laura B. Martínez‐García Gerlinde B. De Deyn Francisco I. Pugnaire David Kothamasi Marcel G. A. van der Heijden 《Global Change Biology》2017,23(12):5228-5236
Substantial amounts of nutrients are lost from soils through leaching. These losses can be environmentally damaging, causing groundwater eutrophication and also comprise an economic burden in terms of lost agricultural production. More intense precipitation events caused by climate change will likely aggravate this problem. So far it is unresolved to which extent soil biota can make ecosystems more resilient to climate change and reduce nutrient leaching losses when rainfall intensity increases. In this study, we focused on arbuscular mycorrhizal (AM) fungi, common soil fungi that form symbiotic associations with most land plants and which increase plant nutrient uptake. We hypothesized that AM fungi mitigate nutrient losses following intensive precipitation events (higher amount of precipitation and rain events frequency). To test this, we manipulated the presence of AM fungi in model grassland communities subjected to two rainfall scenarios: moderate and high rainfall intensity. The total amount of nutrients lost through leaching increased substantially with higher rainfall intensity. The presence of AM fungi reduced phosphorus losses by 50% under both rainfall scenarios and nitrogen losses by 40% under high rainfall intensity. Thus, the presence of AM fungi enhanced the nutrient interception ability of soils, and AM fungi reduced the nutrient leaching risk when rainfall intensity increases. These findings are especially relevant in areas with high rainfall intensity (e.g., such as the tropics) and for ecosystems that will experience increased rainfall due to climate change. Overall, this work demonstrates that soil biota such as AM fungi can enhance ecosystem resilience and reduce the negative impact of increased precipitation on nutrient losses. 相似文献
6.
Uffe N. Nielsen Graham H. R. Osler Colin D. Campbell David F. R. P. Burslem René van der Wal 《Journal of Biogeography》2010,37(7):1317-1328
Aim We used a landscape‐scale study of birch invasion onto heather moorland to determine the consistency of changes in vegetation type and soil properties and in the community composition of five soil organism groups. Our aim was to determine whether the degree to which soil organisms respond to natural changes and/or induced changes (e.g. changes in land‐use type and climate) in habitat is consistent across trophic and taxonomic groups in the context of conservation policies for birch woodland and heather moorland. Location Mainland Scotland. Methods We sampled mesostigmatid mites, oribatid mites, fungi, bacteria and archaea in adjacent patches of birch woodland (dominated by Betula pubescens) and heather moorland (dominated by Calluna vulgaris) at 12 sites for which annual rainfall ranged between 713 and 2251 mm. Differences in community composition were visualized using non‐metric multidimensional scaling based on Bray–Curtis dissimilarities. The factors contributing to differences between habitats within sites were explored using general linear models and those among sites using redundancy analysis. Results The communities of all groups differed between habitats within sites, but only the oribatid mites and fungi differed consistently between habitats across sites. Within sites, dissimilarity in fungal communities was positively related to the difference in C. vulgaris cover between habitats, whereas dissimilarities in bacteria and archaea were positively related to differences in soil pH and C:N ratio between habitats, respectively. Main conclusions The influence of vegetation type and soil properties differed between groups of soil organisms, albeit in a predictable manner, across the 12 sites. Organisms directly associated with plants (fungi), and organisms with microhabitat and resource preferences (Oribatida) were strongly responsive to changes in habitat type. The response of organisms not directly associated with plants (bacteria, archaea) depended on differences in soil properties, while organisms with less clear microhabitat and resource preferences (Mesostigmata) were not strongly responsive to either vegetation type or soil properties. These results show that it is possible to predict the impact of habitat change on specific soil organisms depending on their ecology. Moreover, the community composition of all groups was related to variation in precipitation within the study area, which shows that external factors, such as those caused by climate change, can have a direct effect on belowground communities. 相似文献
7.
The rapidly changing climate in Antarctica is impacting the ecosystems. Since records began, climate changes have varied considerably
throughout Antarctica with both positive and negative trends in temperatures and precipitation observed locally. However,
over the course of this century a more directional increase in both temperature and precipitation is expected to occur throughout
Antarctica. The soil communities of Antarctica are considered simple with most organisms existing at the edge of their physiological
capabilities. Therefore, Antarctic soil communities are expected to be particularly sensitive to climate changes. However,
a review of the current literature reveals that studies investigating the impact of climate change on soil communities, and
in particular nematode communities, in Antarctica are very limited. Of the few studies focusing on Antarctic nematode communities,
long-term monitoring has shown that nematode communities respond to changes in local climate trends as well as extreme (or
pulse) events. These results are supported by in situ experiments, which show that nematode communities respond to both temperature
and soil moisture manipulations. We conclude that the predicted climate changes are likely to exert a strong influence on
nematode communities throughout Antarctica and will generally lead to increasing abundance, species richness, and food web
complexity, although the opposite may occur locally. The degree to which local communities respond will depend on current
conditions, i.e., average temperatures, soil moisture availability, vegetation or more importantly the lack thereof, and the
local species pool in combination with the potential for new species to colonize. 相似文献
8.
How plants communicate using the underground information superhighway 总被引:23,自引:0,他引:23
The rhizosphere is a densely populated area in which plant roots must compete with invading root systems of neighboring plants for space, water, and mineral nutrients, and with other soil-borne organisms, including bacteria and fungi. Root-root and root-microbe communications are continuous occurrences in this biologically active soil zone. How do roots manage to simultaneously communicate with neighboring plants, and with symbiotic and pathogenic organisms within this crowded rhizosphere? Increasing evidence suggests that root exudates might initiate and manipulate biological and physical interactions between roots and soil organisms, and thus play an active role in root-root and root-microbe communication. 相似文献
9.
Plant secondary metabolites (SMs) play crucial roles in plant-environment interactions and contribute greatly to human health. Global climate changes are expected to dramatically affect plant secondary metabolism, yet a systematic understanding of such influences is still lacking. Here, we employed medicinal and aromatic plants (MAAPs) as model plant taxa and performed a meta-analysis from 360 publications using 1828 paired observations to assess the responses of different SMs levels and the accompanying plant traits to elevated carbon dioxide (eCO2), elevated temperature (eT), elevated nitrogen deposition (eN) and decreased precipitation (dP). The overall results showed that phenolic and terpenoid levels generally respond positively to eCO2 but negatively to eN, while the total alkaloid concentration was increased remarkably by eN. By contrast, dP promotes the levels of all SMs, while eT exclusively exerts a positive influence on the levels of phenolic compounds. Further analysis highlighted the dependence of SM responses on different moderators such as plant functional types, climate change levels or exposure durations, mean annual temperature and mean annual precipitation. Moreover, plant phenolic and terpenoid responses to climate changes could be attributed to the variations of C/N ratio and total soluble sugar levels, while the trade-off supposition contributed to SM responses to climate changes other than eCO2. Taken together, our results predicted the distinctive SM responses to diverse climate changes in MAAPs and allowed us to define potential moderators responsible for these variations. Further, linking SM responses to C-N metabolism and growth-defence balance provided biological understandings in terms of plant secondary metabolic regulation. 相似文献
10.
Secondary succession after agriculture abandonment (old-fields) is mostly dominated by exotic grass species. Non-native plant invasions may alter soil fauna, potentially inducing plant-soil feedbacks. Despite their importance in nutrient cycling and plant-soil interactions, meso and macrofauna received less attention than bacteria or fungi. Here we compared the composition of the soil arthropod community in native remnants and plant exotic-dominated old-fields grasslands in the Inland Pampa, Argentina. We sampled independent remnants and old-field grassland plots within a 100 km2 agricultural landscape to test the hypothesis that the abundance of soil arthropod organisms is related to the quality of the plant biomass, whereas the diversity of the soil biota is related to plant species richness, resulting in a different soil biota composition because of differing plant communities. When compared to non-invaded remnant grasslands, soil activity and soil food-web characteristics of the old-fields sites included: 1. Higher total arthropod abundance, particularly of Isopoda, Pseudoescorpionida and Blattaria; 2. Lower abundance of Hymenoptera and Enthomobryomorpha (Collembola); 3. Lower diversity, and evenness, but similar richness of soil organisms orders; 4. Higher soil respiration rates and soil temperature; and 5. Higher total soil N and K+content, but lower soil P content. These results illustrate that soil arthropod composition can vary widely within grasslands patches depending on plant species composition. Also, the more diverse plant community of remnant grasslands supports a more diverse soil biota, although soil activity is slower. Our results support the strong linkage between plant community and soil arthropod composition and suggest that changes in soil biota composition might promote plant-soil feedback interactions inducing the persistence of these alternative grassland states in new agricultural human-modified landscapes. 相似文献