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- Douglas A. Landis (1)
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- Wim H. Putten van der (1)
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- E.R.J. Wubs (1)
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Nonlinear responses of soil nematode community composition to increasing aridity
Xiong, Dan ; Wei, Cun Zheng ; Wubs, Jasper E.R. ; Veen, G.J. ; Liang, Wenju ; Wang, Xiaobo ; Li, Qi ; Putten, Wim H. Van der; Han, Xingguo - \ 2019
Global Ecology and Biogeography (2019). - ISSN 1466-822X
aridity - biodiversity - global climate change - grassland transect - nonlinear response - soil nematode community
Aim: Increasing aridity under global change is predicted to have a profound impact on the structure and functioning of terrestrial ecosystems, yet we have a poor understanding of how belowground communities respond. In order to understand the longer term responses of different trophic levels in the soil food web to increasing aridity, we investigated the abundance, richness and community similarity of the soil nematode community along a 3,200 km aridity gradient. Location: A transect across semi-arid and arid grasslands in Northern China, where the aridity ranges from.43 to.97. Time period: July and August 2012. Major taxa studied: Soil-borne Nematoda. Methods: We used generalized additive (mixed) models to analyse the abundance, richness and community similarity patterns of soil nematodes. We used structural equation modelling (SEM) to disentangle the direct and indirect environmental drivers (aridity, soil and plant variables) of the nematode community. Results: The abundance, richness and similarity of nematode communities declined nonlinearly with increasing aridity. The most pronounced decline in nematode richness and community similarity occurred in arid conditions (aridity >.80). However, the shape of the response to aridity differed among nematode feeding groups. In arid conditions, the abundance and richness of bacterial feeders were less sensitive to changes in aridity than for fungal feeders. The SEM analysis revealed that nematode community responses to aridity were not mediated via changes in plant and soil variables, but instead were affected directly by aridity. Main conclusions: Our results showed that in mesic grasslands, increasing aridity primarily caused a decline in nematode abundance, whereas increasing aridity in xeric grasslands led to a loss of nematode diversity. The nonlinear responses of nematodes to aridity could also result in nonlinear shifts in ecosystem functioning, because soil nematodes operate at various trophic levels in the soil food web, thereby influencing the performance of plants, soil biodiversity and biogeochemical cycling.
Applying the aboveground-belowground interaction concept in agriculture: Spatio-temporal scales matter
Veen, G.F. ; Jasper Wubs, E.R. ; Bardgett, Richard D. ; Barrios, Edmundo ; Bradford, Mark A. ; Carvalho, Sabrina ; Deyn, Gerlinde B. De; Vries, Franciska T. de; Giller, Ken E. ; Kleijn, David ; Landis, Douglas A. ; Rossing, Walter A.H. ; Schrama, Maarten ; Six, Johan ; Struik, Paul C. ; Gils, Stijn van; Wiskerke, Johannes S.C. ; Putten, Wim H. van der; Vet, Louise E.M. - \ 2019
Frontiers in Ecology and Evolution 7 (2019)AUG. - ISSN 2296-701X
Above-belowground biotic interactions - Agroecology - Spatio-temporal scales - Steering communities - Sustainable agriculture
Interactions between aboveground and belowground organisms are important drivers of plant growth and performance in natural ecosystems. Making practical use of such above-belowground biotic interactions offers important opportunities for enhancing the sustainability of agriculture, as it could favor crop growth, nutrient supply, and defense against biotic and abiotic stresses. However, the operation of above-and belowground organisms at different spatial and temporal scales provides important challenges for application in agriculture. Aboveground organisms, such as herbivores and pollinators, operate at spatial scales that exceed individual fields and are highly variable in abundance within growing seasons. In contrast, pathogenic, symbiotic, and decomposer soil biota operate at more localized spatial scales from individual plants to patches of square meters, however, they generate legacy effects on plant performance that may last from single to multiple years. The challenge is to promote pollinators and suppress pests at the landscape and field scale, while creating positive legacy effects of local plant-soil interactions for next generations of plants. Here, we explore the possibilities to improve utilization of above-belowground interactions in agro-ecosystems by considering spatio-temporal scales at which aboveground and belowground organisms operate. We identified that successful integration of above-belowground biotic interactions initially requires developing crop rotations and intercropping systems that create positive local soil legacy effects for neighboring as well subsequent crops. These configurations may then be used as building blocks to design landscapes that accommodate beneficial aboveground communities with respect to their required resources. For successful adoption of above-belowground interactions in agriculture there is a need for context-specific solutions, as well as sound socio-economic embedding.
The steering role of plant-soil interactions in natural community dynamics and nature restoration
Wubs, Engel Reinder Jasper - \ 2017
Wageningen University. Promotor(en): W.H. Putten; T.M. Bezemer. - Wageningen : Wageningen University - ISBN 9789463434447 - 242
soil plant relationships - soil - plants - ecological restoration - terrestrial ecosystems - soil inoculation - plant communities - soil ecology - bodem-plant relaties - bodem - planten - ecologisch herstel - terrestrische ecosystemen - bodeminoculatie - plantengemeenschappen - bodemecologie
Biodiversity is declining worldwide and many ecosystems have been degraded due to human actions. There have been many attempts to restore degraded ecosystems, but restoration success varies. Past human management has left important abiotic and biotic legacies and active intervention is needed to overcome these legacies. Legacy effects include altered abiotic conditions and limited availability of appropriate seeds. However, plants also have many interactions with the myriad organisms that inhabit the soil. Soil biota include e.g. bacteria, fungi, nematodes, collembolan, and mites. Restoring plant-soil interactions may be key to successful ecological restoration, because studies on natural succession in ecosystems show that both plant and soil communities develop in concert. In addition, late-successional soil communities promote the performance of late-succession plant species that are often the target species for restoration. The aims of my thesis were to 1) test whether inoculation of living soil can improve restoration of species-rich grasslands and dry heathlands, and 2) understand how plant-soil interactions affect plant composition and diversity.
In a large-scale field experiment, called “Reijerscamp-experiment”, I tested the potential of soil inoculation to speed up ecosystem restoration. On a former arable field large areas of on average 0.5 ha were inoculated with a thin layer of <1 cm living soil, which was taken either from a mid-succession grassland or a dry-heathland. After six years I monitored the species composition of the vegetation and the soil community. I found that both types of inoculum had substantially altered the community composition of both soil and vegetation. Moreover, the soil inocula had caused a shift in the direction of the respective donor communities. In a parallel mesocosm experiment I repeated the experiment while sowing a standardized species-rich seed mixture to ensure that seed availability was the same in all treatments. Also in this case the sown plant community developed towards the respective communities found in the donor sites. Consequently the soil community is, at least in part, able to steer plant community composition in the field.
I also tested how mixtures of inocula from different donor systems affect restoration success. In a greenhouse experiment I made replacement series of soil inocula sourced from arable fields, mid-succession grasslands and dry heathlands and monitored the responses of target and ruderal plant species. The target species all responded positively to higher proportions of heathland material in the inoculum, while the responses of the ruderal species were variable. Interestingly, a 50:50 mixture of arable and heathland inoculum strongly reduced the growth of the ruderal species. Soil inoculation may be considered as a way of microbiome engineering, which is a newly emerging field mainly used to improve human health and agricultural production. My results show that conceptually similar techniques can be applied to improve inocula for the restoration of ecological communities.
In a second field experiment I tested the long-term consequences of soil inoculation with and without sowing mid-successional plant species for plant and soil community composition. I found that sowing strongly altered plant community composition for over two decades. Soil inoculation, on the other hand, substantially altered the composition of the soil nematode community and that these effects persisted for at least 15 years. However, in contrast to the Reijerscamp experiment, the effect of soil inoculation on vegetation composition was transient. I propose that in this case the presence of an intact arable top soil, as well as perhaps a too minimal difference between the composition of the donor and recipient soil communities may have limited the impact of the soil inocula.
In general, the restoration of plant cover and a number of common (‘matrix’) plant species can be achieved using standard approaches, e.g. reducing site fertility and providing seed material, but creating conditions that allow for coexistence of both locally dominant and rare subordinate species proves much more elusive. Fundamental knowledge on how biodiversity is regulated is needed to restore diverse plant communities including the rare species. Testing plant-soil feedback provides a way to directly study the net consequences of the myriad interactions between plants and soil biota for plant performance and community composition. However, while both plants and soil communities are strongly heterogeneous in space and time, spatiotemporally explicit tests of plant-soil feedback are rare.
In a greenhouse experiment I studied how spatial heterogeneity in plant-soil feedbacks influence plant communities. I found that when multiple species conditioned the soil, plant performance was reduced compared to mono-specific soil conditioning. This reduction in competitive ability led to a higher plant diversity in the experimental communities. The plant responses were not related to differences in abiotic conditions, but soil conditioning induced clear changes in fungal community composition. Recent meta-analyses and experiments have shown that spatial heterogeneity in abiotic conditions only promotes plant diversity when the grain of the heterogeneity is larger than the size of individual plants. When it is smaller, heterogeneity simply selects for those species that have the highest root plasticity and this leads to lower plant diversity. Together, these results suggest that spatial heterogeneity in abiotic conditions only promotes plant beta diversity, while interaction with the soil community, primarily soil-borne antagonists, maintains plant alpha diversity.
Finally, I used repeated soil conditioning by conspecific and heterospecific species to show that soil feedbacks may carry over across soil conditioning periods. In contrast to what is commonly assumed my data show that heterospecific soil-conditioning can result in equally negative PSF as repeated conspecific soil-conditioning and repeated conspecific soil-conditioning does not always lead to stronger negative feedback. Instead, the particular sequence of plant species that successively condition the soil strongly determines the sign and magnitude of PSF. These results highlight the need to incorporate sequential soil-conditioning in models of plant communities and effective crop-rotations.
In conclusion, plant-soil interactions are a key aspect in the natural dynamics of plant communities and can be used to improve restoration of semi-natural ecosystems. Abiotic conditions and dispersal ability determine which species may occur in a given site. However, at small spatial scales plant-soil feedbacks and particularly interactions with soil borne antagonists can enhance plant species diversity. Manipulation of the soil community, through inoculation of soil from well-developed donor sites can speed up natural succession and even steer its direction in the field. However, soil inoculation success will not be universal and depends on the match in abiotic conditions of donor and recipient sites, as well as the community composition of the inoculum and the resident communities. Future studies are needed to test the success of introducing soil communities across environmental gradients.
|Planteninventarisatie: Voorovergebogen de grond aftasten (interview met Jasper Wubs)
Wubs, E.R.J. - \ 2012