scholarly journals Plant species richness, identity and productivity differentially influence key groups of microbes in grassland soils of contrasting fertility

2010 ◽  
Vol 7 (1) ◽  
pp. 75-78 ◽  
Author(s):  
Gerlinde B. De Deyn ◽  
Helen Quirk ◽  
Richard D. Bardgett

The abundance of microbes in soil is thought to be strongly influenced by plant productivity rather than by plant species richness per se . However, whether this holds true for different microbial groups and under different soil conditions is unresolved. We tested how plant species richness, identity and biomass influence the abundances of arbuscular mycorrhizal fungi (AMF), saprophytic bacteria and fungi, and actinomycetes, in model plant communities in soil of low and high fertility using phospholipid fatty acid analysis. Abundances of saprophytic fungi and bacteria were driven by larger plant biomass in high diversity treatments. In contrast, increased AMF abundance with larger plant species richness was not explained by plant biomass, but responded to plant species identity and was stimulated by Anthoxantum odoratum . Our results indicate that the abundance of saprophytic soil microbes is influenced more by resource quantity, as driven by plant production, while AMF respond more strongly to resource composition, driven by variation in plant species richness and identity. This suggests that AMF abundance in soil is more sensitive to changes in plant species diversity per se and plant species composition than are abundances of saprophytic microbes.

Oecologia ◽  
2021 ◽  
Vol 195 (1) ◽  
pp. 213-223
Author(s):  
Mark A. Lee ◽  
Grace Burger ◽  
Emma R. Green ◽  
Pepijn W. Kooij

AbstractPlant and animal community composition changes at higher elevations on mountains. Plant and animal species richness generally declines with elevation, but the shape of the relationship differs between taxa. There are several proposed mechanisms, including the productivity hypotheses; that declines in available plant biomass confers fewer resources to consumers, thus supporting fewer species. We investigated resource availability as we ascended three aspects of Helvellyn mountain, UK, measuring several plant nutritive metrics, plant species richness and biomass. We observed a linear decline in plant species richness as we ascended the mountain but there was a unimodal relationship between plant biomass and elevation. Generally, the highest biomass values at mid-elevations were associated with the lowest nutritive values, except mineral contents which declined with elevation. Intra-specific and inter-specific increases in nutritive values nearer the top and bottom of the mountain indicated that physiological, phenological and compositional mechanisms may have played a role. The shape of the relationship between resource availability and elevation was different depending on the metric. Many consumers actively select or avoid plants based on their nutritive values and the abundances of consumer taxa vary in their relationships with elevation. Consideration of multiple nutritive metrics and of the nutritional requirements of the consumer may provide a greater understanding of changes to plant and animal communities at higher elevations. We propose a novel hypothesis for explaining elevational diversity gradients, which warrants further study; the ‘nutritional complexity hypothesis’, where consumer species coexist due to greater variation in the nutritional chemistry of plants.


2013 ◽  
Vol 41 (7) ◽  
pp. 657-664 ◽  
Author(s):  
Hai Wang ◽  
Zheng-Xin Chen ◽  
Xiao-Yu Zhang ◽  
Si-Xi Zhu ◽  
Ying Ge ◽  
...  

2016 ◽  
Vol 113 (15) ◽  
pp. 4086-4091 ◽  
Author(s):  
Samuel M. Simkin ◽  
Edith B. Allen ◽  
William D. Bowman ◽  
Christopher M. Clark ◽  
Jayne Belnap ◽  
...  

Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these environmental factors. We assessed the effect of N deposition on herbaceous richness for 15,136 forest, woodland, shrubland, and grassland sites across the continental United States, to address how edaphic and climatic conditions altered vulnerability to this stressor. In our dataset, with N deposition ranging from 1 to 19 kg N⋅ha−1⋅y−1, we found a unimodal relationship; richness increased at low deposition levels and decreased above 8.7 and 13.4 kg N⋅ha−1⋅y−1 in open and closed-canopy vegetation, respectively. N deposition exceeded critical loads for loss of plant species richness in 24% of 15,136 sites examined nationwide. There were negative relationships between species richness and N deposition in 36% of 44 community gradients. Vulnerability to N deposition was consistently higher in more acidic soils whereas the moderating roles of temperature and precipitation varied across scales. We demonstrate here that negative relationships between N deposition and species richness are common, albeit not universal, and that fine-scale processes can moderate vegetation responses to N deposition. Our results highlight the importance of contingent factors when estimating ecosystem vulnerability to N deposition and suggest that N deposition is affecting species richness in forested and nonforested systems across much of the continental United States.


Author(s):  
Xue Yang ◽  
Meng Yuan ◽  
Jixun Guo ◽  
Lianxuan Shi ◽  
Tao Zhang

We examined the impacts of warming, nitrogen (N) addition and suppression of arbuscular mycorrhizal fungi (AMF) on soil bacterial and fungal richness and community composition in a field experiment. AMF root colonization and the concentration of an AMF-specific phospholipid fatty acid (PLFA) were significantly reduced after the application of the fungicide benomyl as a soil drench. Warming and N addition had no independent effects but interactively decreased soil fungal richness, while warming, N addition and AMF suppression together reduced soil bacterial richness. Soil bacterial and fungal species diversity was lower with AMF suppression, indicating that AMF suppression have negative effect on microbial diversity. Warming and N addition decreased the net loss of plant species and the plant species richness, respectively. AMF suppression reduced plant species richness and the net gain of plant species but enhanced the net loss of plant species. Structural equation modeling (SEM) demonstrated that the soil bacterial community responded to the increased soil temperature (ST) induced by warming and the increased soil available N (AN) induced by N addition through changes in AMF colonization and plant species richness; ST directly affected the bacterial community, but AN affected both the soil bacterial and fungal communities via AMF colonization. In addition, higher mycorrhizal colonization increased the plant species richness by increasing the net gains in plant species under warming and N addition. IMPORTANCE Arbuscular mycorrhizal fungi (AMF) can influence the composition and diversity of plant communities. Previous studies have shown that climate warming and N deposition reduce the effectiveness of AMF. However, how AMF affects soil bacterial and fungal communities under these global change drivers are still poorly understood. A 4-year field study revealed that AMF suppression decreased bacterial and fungal diversity irrespective of warming or N addition, while AMF suppression interacted with warming or N addition to reduce bacterial and fungal richness. In addition, bacterial and fungal community compositions were determined by mycorrhizal colonization which was regulated by soil AN and ST. These results suggest that AMF suppression can aggravate the severe losses to native soil microbial diversity and functioning caused by global changes and thus AMF plays a vital role in maintaining belowground ecosystem stability in the future.


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