Pioneer Grass Research Articles

Epichloë bromicola Enhances Elymus dahucirus Plant Growth and Antioxidant Capacity under Cadmium Stress

Elymus dahucirus is an essential plant for ecological restoration in fragile ecological areas and mining area restoration. As lawn grass, it can quickly cover soil and prevent soil erosion, so it is commonly used as a pioneer grass for lawn greening and slope protection. In recent years, with the development of mineral resources, Qinghai–Tibet Plateau soil is facing the threat of heavy metal cadmium (Cd) pollution. E. dahuricus can host the filamentous fungus Epichloë bromicola. To make better use of the advantages that Epichloë bring to host plants to alleviate heavy metal pollution in soil, plant growth and antioxidant capacity effects on E. bromicola infected (E+) and uninfected (E−) E. dahuricus were determined under Cd stress. During Cd treatment, plant growth was decreased by Cd stress, while E+ plants exhibited equal or better growth compared to E− plants. Cd treatment induces a proline and antioxidant enzyme burst in infected plants, while malondialdehyde (MDA) increases. E. bromicola improved plant growth and antioxidant capacity. E. dahuricus breeding strategies could use the information here in efforts to improve the performance of E. dahuricus in both environmental protection and agronomic contexts.

Abiotic legacies mediate plant–soil feedback during early vegetation succession on rare earth element mine tailings

Abstract An increasing number of studies have shown how feedback interactions between plants and soil can influence primary and secondary succession. However, very little is known about the patterns and mechanisms of such plant–soil feedbacks on stressed mine tailings ecosystem, which can be severely contaminated by a range of toxic elements. In a two‐phase plant–soil feedback experiment based on the rare earth element (REE) mine tailing soil, we investigated biotic (changes in bacterial and fungal communities) and abiotic (changes in chemical properties) legacies of three pioneer grass species, and examined feedback effects of three grasses, two legumes and two woody plants with different root traits. Positive plant–soil feedbacks were found in Miscanthus sinensis, Paspalum thunbergii and Tephrosia candida, and neutral feedbacks were observed in the other four plants. These effects corresponded with an increase in nutrients and total organic carbon, as well as a decrease in acidity and extractable aluminium and REEs. There were less signs of biotic changes in the conditioned tailings. The correlation analysis suggested a relationship between plants' responses to soil legacies and root traits, as well as root economics spectrum. On the mine tailings, acquisitive species with higher specific root length appeared to have greater potential for positive feedback. Synthesis and application. Our study shows that early succession on contaminated rare earth element mine tailings may lead to more positive plant–soil feedback than predicted based on results of non‐contaminated soils, mainly due to the alleviation of abiotic stress in tailings. Therefore, the improvement of specific abiotic soil stress and the trait‐based selection of acquisitive plants should be preferentially considered to promote the primary restoration of degraded land.

Dark septate endophytic fungi associated with pioneer grass inhabiting volcanic deposits and their functions in promoting plant growth

Abstract. Growth of the pioneer grass Miscanthus condensatus, one of the first vegetation types to be established on volcanic deposits, is promoted by root-associated fungi, particularly dark septate endophytes (DSEs). Fungal taxa within DSEs colonize the root of Miscanthus condensatus in oligotrophic Andosol, and their function in plant growth promotion remains largely unknown. We, therefore, comprehensively assessed the composition of the DSE community associated with Miscanthus condensatus root in volcanic ecosystems using the approaches of both metabarcoding (next-generation sequencing) and isolation (culturing). Also, the promotion effects of DSEs on plant growth (rice as a proxy) were evaluated by inoculation of core isolates to rice roots. Here, we found the following: (i) 70 % of culturable fungi that colonized Miscanthus condensatus phylogenetically belonged to DSEs; (ii) seven orders were identified by both sequencing and culturing methods; and (iii) inoculation of DSE isolates (Phialocephala fortinii, P. helvetica, and Phialocephala sp.) validated their effects on rice growth, particularly under an extremely low pH condition (compared to the control without inoculation, rice biomass was enhanced 7.6-fold after inoculation of P. fortinii). This study helps improve our understanding of the community of Miscanthus condensatus-associated DSE fungi and their functions in promoting plant growth.

Effect of Harvest Time on the Seed Yield and Quality of Kengyilia melanthera

Kengyilia melanthera is one of the most important forages, and has received significant attention as a desirable ecological pioneer grass for conserving grasslands and mitigating degradation pressure in a region. It is widely distributed in the alpine sandy meadow zone of the Eastern Qinghai–Tibet Plateau (QTP). Therefore, determining the optimal harvest time of this species is critical. A two-year field experiment (2016–2017) was utilized in this study to evaluate the impact of eight harvest times on the seed yield and quality of K. melanthera ‘Aba’. The results show that the fresh weight (FW), dry weight (DW), seed yield (SY), thousand-grain weight (TGW), accelerated aging germination percentage (AAGP), and dehydrogenase activity (DA) of seeds increased with the extension of harvest time in two trial years, while the water content (WC) of seeds decreased. In both trial years, the germination percentage (GEP), germination potential (GP), and acid phosphatase activity (APA) of seeds increased initially and then decreased with the extension of harvest time. The comprehensive evaluation of the membership function and hierarchical clustering revealed that the 30th day after peak anthesis was the optimal harvest time for both 2016 and 2017. During this time, FW, DW, SY, TGW, AAGP, DA, WC, GEP, GP, and APA reached their optimal value, with 0.815 g, 0.518 g, 1773.67 kg·hm−2, 143.81%, 66%, 16.23 µg·mL−1, 36.01%, 87%, 85%, and 2.50 nmol·min−1 in 2016 and 0.805 g, 0.515 g, 1847.42 kg·hm−2, 133.96%, 65%, 16.52 µg·mL−1, 36.04%, 86.5%, 83.5%, and 2.55 nmol·min−1 in 2017, respectively. This study uncovers several high-efficiency and long-term technological solutions for cultivating high yields and quality production of K. melanthera in East QTP.

Effect of nitrogen fertilizer on seed yield and quality of Kengyilia melanthera (Triticeae, Poaceae).

Widely distributed in the alpine sandy grassland in east Qinghai-Tibet Plateau (QTP), Kengyilia melanthera is considered as an ideal pioneer grass for the restoration of degraded and desertification grassland in the region. Under the special ecological and climatic conditions in the northwest Sichuan plateau located in east QTP, it is of great significance to optimize the amount of nitrogen fertilizer for the seed production of this species. The impact of nitrogen (N) fertilizer application on seed yield and quality of K. melanthera ‘Aba’, the only domesticated variety in the Kengyilia genus of Poaceae, was investigated based on two-year field experiments in the northwestern Sichuan plateau. The results showed that with the increase of N fertilizer application, the number of tillers, number of fertile tillers, 1,000-seed weight and seed yield of this species increased likewise. The optimum N fertilizer rate deduced in the present study was 180 kg·hm−2, where the number of fertile tillers 1,000-seed weight and seed yield reached the peak values. Interestingly, the standard germination rate, germination energy, accelerated aging germination rate, dehydrogenase and acid phosphatase activity of seeds were not affected by the increasing the input of N fertilizer. The comprehensive evaluation of membership function showed that the optimal N fertilizer treatment was 180 kg·hm−2 both for 2016 and 2017. This study provided a certain practical suggestion for the improvement of seed production of K. melanthera in the northwest Sichuan plateau.

Root Traits and Erosion Resistance of Three Endemic Grasses for Estuarine Sand Drift Control

In southern Taiwan, rivers sporadically cease to flow and dry up in winter. The exposed dry riverbeds are very vulnerable to wind erosion. The strong northeast monsoon often induces serious estuarine sand drift and fugitive dust, which cause damages to agricultural crops, human health and infrastructures. Giant reed (Arundo formosana), common reed (Phragmite australis) and the wild sugarcane (Saccharum spontaneum) are pioneer grass species in estuary areas. They have great potential to reduce wind erosion and control windblown dust on agricultural lands. Nevertheless, their root traits, biomechanical characteristics and wind erosion resistance have not been investigated. In this research, the root traits were investigated utilizing the hand digging technique and the WinRHIZOPro System. Root pullout resistance and root tensile strength were estimated using vertical pullout and root tensile tests. Wind tunnel tests were executed to evaluate the wind erosion resistance using six-month-old plants. The results demonstrated that the growth performance and root functional traits of S. spontaneum are superior to those of A. formosana and P. australis. Additionally, the root anchorage ability and root tensile strength of S. spontaneum plants are notably greater than those of A. formosana and P. australis plants. Furthermore, the results of the wind tunnel tests showed that the wind erosion resistance of A. formosana is remarkably higher than those of S. spontaneum and P. australis. This study demonstrates that A. formosana and S. spontaneum are superior to P. australis, considering root traits, root anchorage ability, root tensile strength and wind erosion resistance. Taken together, our results suggest that S. spontaneum and P. australis are favorable for riverbed planting, while A.formosana is applicable for riverbank planting in estuary areas. These results, together with data on the acclimation of estuarine grasses in waterlogged soils and brackish waters, provide vital information for designing planting strategies of estuary grasses for the ecological engineering of estuarine sand drift control.

High resolution environmental conditions of the last interglacial (MIS5e) in the Levant from Sr, C and O isotopes from a Jerusalem stalagmite

The southern Levant region at the fringe of the Saharan-Arabian deserts is particularly vulnerable to warming and desertification, therefore reconstruction of the hydroclimate conditions of this region during periods of past climate change provide important insight on what may occur in the future. Here we report on high temporal resolution 87 Sr/ 86 Sr, δ 13 C and δ 18 O isotope data of a stalagmite from the Har Nof cave in Jerusalem, demonstrating major climate changes during the last interglacial MIS5e between ~131–116 ka. We combine also data from other caves in Israel and the ICDP Dead Sea deep drill core. The following palaeoenvironmental history is observed: • At 131–127.5 ka, Jerusalem experienced moderate Mediterranean climate conditions. Desert dust accumulated above the cave, while salt deposition occurred in the Dead Sea. • At 127.5–122 ka, across the MIS5e insolation peak and Sapropel S5 interval in the Mediterranean, highly negative speleothem δ 18 O indicate both Mediterranean and southern (tropical) derived rains. Surface cover diminished, and by 122 ka the 87 Sr/ 86 Sr and δ 13 C values indicate complete soil removal above the cave. Very high temperatures and intensive fires caused the removal of C 3 vegetation. The rainfall season shifted from winter to summer with tropical-sourced precipitation. • At 122–120.5 ka, the 87 Sr/ 86 Sr ratios indicate contributions of sea salts. Extremely high speleothem δ 13 C values indicate no vegetation. • At ~120.5–118 ka there was higher rainfall and lower temperatures, associated with re-establishment of vegetation, including savannah-like C 4 pioneer grasses that appeared on soil patches. • At 118–116 ka, the sedimentation rate of Har Nof AF12 stalagmite is extremely low, indicating regional aridity, coinciding with massive salt deposition in the Dead Sea. • Last interglacial unstable environment in the southern Levant is demonstrated. • Heat, fires and rainfall season shift caused loss of Mediterranean vegetation. • Tropical-sourced summer rains intruded the southern Levant. • Savannah-like vegetation replaced Mediterranean forest. • Reconstruction is based on speleothems, corroborated by models and Dead Sea records.

Isolation of Mercury-Resistant Endophytic and Rhizosphere Microorganisms from Grasses in Abandoned Gold Mining Area

There were about 900 hotspots of artisanal and small scale gold mining (ASGM) in Indonesia that recovered gold through amalgamation and cyanidation techniques. Amalgamation technique causes mercury (Hg) pollution to the soil. This study was a preliminary study that aimed to isolate Hg-resistant endophytic and rhizosphere microorganisms from pioneer grasses in the Hg-polluted soil. The most potential microorganism will be used for Hg phytoremediation in the future study. Pioneer grasses were collected from the abandoned gold mining area in Central Lombok Regency, West Nusa Tenggara. Total microorganisms were counted using Colony Forming Unit (CFU) or Standard Plate Count. The microorganism colony was characterized based on morphological characteristics. Hg-resistant endophytic and rhizosphere microorganisms were successfully isolated from pioneer grass (Cynodon dactylon and Eleusine indica) in the study site. The colonies of rhizosphere microorganisms were diverse morphologically compared to endophytic microorganisms based on the number of isolated microorganisms, 20 isolates and 17 isolates, respectively. The density of rhizosphere microorganisms was higher (96%) than endophytic microorganisms (4%). The density of rhizosphere bacteria and fungi were 47x103 and 2x103 CFU g-1, respectively. However, the density of endophytic bacteria and fungi were only 2x103 and 1x103 CFU g-1, respectively.
 Keywords: endophytic microorganism, Hg-resistant, microorganism density, rhizosphere microorganism

Tussock Circumference, Land Use Type and Drought Variably Influence Spider Assemblages Associated with Hyparrhenia hirta Grass Tussocks

Many human activities have an impact on the fauna and flora of the South African Grassland Biome, including agriculture, fire and urbanisation. Disturbances in grassland habitats often result in Hyparrhenia hirta, a native pioneer grass species, establishing dense stands. Here the assemblage composition, species richness and abundance of spiders associated with H. hirta tussocks was investigated at three grassland sites (annually burnt, suburban local road traffic and undisturbed control) in the central Free State Province of South Africa during winter 2015 and 2016. Further, inter-annual differences during a period of intense drought were evaluated. An increase in spider species richness, abundance and different assemblage composition with increased tussock height and basal circumference was expected, and we predicted these effects would differ between land use types. Overall, Tibellus spp. immatures (Philodromidae) and Poachelas striatus Haddad & Lyle, 2008 (Trachelidae) were the most abundant spider species, while Philodromidae and Gnaphosidae were the most abundant spider families at all three sites during both years. The most species-rich families were Gnaphosidae, Salticidae and Thomisidae. Over the two-year sampling period there was a significant decline in overall spider abundance (58.09 %) and species richness (28.17 %), which could be explained by the cumulative effects of a severe drought experienced in central South Africa during 2015 and 2016. Species richness and assemblage composition were influenced by tussock basal circumference and disturbance effects, but not by tussock height. Several species were associated with the control site, while certain diversity metrics of the burnt and road verge sites were more stable, pointing to the importance of primary productivity in the former and water in the latter, for spider diversity. Trade-offs related to disturbance need to be carefully considered when developing management strategies for biodiversity.

Strength and size of phosphorus-rich patches determine the foraging strategy of Neyraudia reynaudiana

BackgroundUnder natural conditions, soil nutrients are heterogeneously distributed, and plants have developed adaptation strategies to efficiently forage patchily distributed nutrient. Most previous studies examined either patch strength or patch size separately and focused mainly on root morphological plasticity (increased root proliferation in nutrient-rich patch), thus the effects of both patch strength and size on morphological and physiological plasticity are not well understood. In this study, we examined the foraging strategy of Neyraudia reynaudiana (Kunth) Keng ex Hithc, a pioneer grass colonizing degraded sites, with respect to patch strength and size in heterogeneously distributed phosphorus (P), and how foraging patchily distributed P affects total plant biomass production. Plants were grown in sand-culture pots divided into ½, ¼, 1/6 compartments and full size and supplied with 0 + 0/30, 0 + 7.5/30 and 7.5 + 0/30 mg P/kg dry soil as KH2PO4 or 0 + 15/15, 0 + 18.5/ 18.5, 7.5 + 15/15 mg kg − 1 in the homogenous treatment. The first amount was the P concentration in the central region, and that the second amount was the P concentration in the outer parts of the pot.ResultsAfter 3 months of growth under experimental conditions, significantly (p < 0.05) high root elongation, root surface area, root volume and average root diameter was observed in large patches with high patch strength. Roots absorbed significantly more P in P-replete than P-deficient patches. Whole plant biomass production was significantly higher in larger patches with high patch strength than small patches and homogeneous P distribution.ConclusionThe result demonstrates that root morphological and physiological plasticity are important adaptive strategies for foraging patchily distributed P and the former is largely determined by patch strength and size. The results also establish that foraging patchily distributed P resulted in increased total plant biomass production compared to homogeneous P distribution.

Photosynthetic Properties of Miscanthus condensatus at Volcanically Devastated Sites on Miyake-jima Island.

How photosynthetic-related leaf traits of non-nitrogen (N)-fixing pioneer species respond to extreme habitat conditions of primary succession is still not well-elucidated, especially in volcanically N-deplete habitats. The effect of N-deplete soil on photosynthetic-related leaf traits can provide a basis for predicting how plants adjust their strategies to adapt to such habitats. To examine the responses of leaf traits to extreme conditions, we investigated Miscanthus condensatus (a non-N-fixing C4 pioneer grass) which grows on a volcanically devastated area on Miyake-jima Island, Japan, in which the volcanic ash has been deposited for 17–18 years since the 2000-year eruption. Leaf N content (Narea), light-saturated photosynthetic rate (Amax), and photosynthetic N use efficiency (PNUE) in three contrasting study sites: bare land (BL), shrub land gap (SLG), and shrub land under canopy (SLUC) were determined. Results indicated that compared to previous studies and internal comparison of Miyake Island, M. condensatus in BL was able to maintain a relatively high Amax, Narea and PNUE. The higher Amax was in part a result of the higher PNUE. This is a characteristic necessary for its successful growth in N-deplete soils. These results suggest that M. condensatus has photosynthetic-related advantages for adaptation to volcanically N-deplete habitats.

Is the soil seed bank a reliable source for passive restoration of bush-cleared semi-arid rangelands of South Africa?

BackgroundBush clearing of encroached rangelands is crucial for restoration of herbaceous cover and diversity. Regeneration after bush clearing depends largely on the soil seed bank (SSB) size and composition. To assess the potential of the SSB to facilitate post-clearing herbaceous restoration, we examined the SSB density, composition and diversity and similarity between SSB and aboveground vegetation (AGV).MethodsThe study was conducted in semi-arid rangelands of Maseding and Kgomokgomo in North-West Province of South Africa. In each rangeland, all woody plants in three 1250 m2 plots were cut using saws and loppers, with the stumps treated with picloram. Paired observations were conducted in cleared and uncleared microsites. Soil samples were collected at three depths (0–10, 10–20 and 20–30 cm) in each microsite in April (pre-treatment), August, October and December 2016 and in April and August 2017. SSB was assessed using seedling emergence method, whereas pre- and post-clearing surveys of AGV were conducted in February 2016 and 2017, respectively.ResultsCleared microsites had significantly (p < 0.01) higher seed bank densities (1872 and 693 seeds m-2 at Maseding and Kgomokgomo, respectively) relative to uncleared microsites in August 2017, with grasses accounting for higher densities than other plant functional groups in the upper 0–10 cm. Pioneer grasses (Aristida congesta subsp. barbicollis, Brachiaria eruciformis and Tragus berteronianus) and invasive forbs (Bidens pilosa and Schkuhria pinnata) dominated the SSB in cleared microsites at Maseding, whereas succulents (Portulaca spp.) and pioneer grasses (T. berteronianus and Urochloa mosambicensis) were abundant at Kgomokgomo in August 2017. SSB and AGV were dissimilar until December 2016; thereafter, similarity increased significantly (p < 0.05) in cleared microsites (Sørensen’s coefficient = 0.60 to 0.66 at Maseding and 0.43 to 0.52 at Kgomokgomo) compared to uncleared microsites. Species diversity was highest in August 2016 and April 2017 at Maseding, but it did not differ between two microsites (p > 0.05). At Kgomokgomo, SSB was more diverse in cleared than uncleared microsites in April and August 2017.ConclusionHigh seed bank densities in the upper soil layer in cleared microsites would promote passive restoration, but regeneration is likely to be initiated by early successional species. However, close monitoring and eradication of invasive forbs and succulents is necessary following bush clearing. The tendency of SSB resembling AGV over time in cleared microsites signifies that seed production from AGV is important for passive restoration following bush clearing.

Ecological and Floristic Features of Pioneer Grass Vegetation on Automorphic Sandy Soils as a Pine-Forest Recovery Phase in the Southern Part of the Nonchernozem Zone of Russia

This article addresses the phytocoenotic diversity of psammophytic grass communities in the southern part of the nonchernozem zone of Russia, where the restoration of Scots pine (Pinus sylvestris) is either ongoing or potentially possible. Community structure and composition formation trends developing under the influence of key environmental and coenotic factors have been identified. The studies were carried out in Bryansk, Kaluga, and Smolensk oblasts in 2010–2018; over 150 geobotanical releves of psammophytic grass communities have been produced. This vegetation belongs to the class Koelerio-Corynephoretea Klika 1931, which combines dry grasslands on sandy soils and rocky outcrops in the temperate and boreal zones of Europe, on islands of the North Atlantic, and in Greenland. Differences between environmental regimes of various habitats occupied by psammophytic communities have been identified. In most cases, the environmental amplitudes of syntaxonomic units vary significantly by the three key edaphic factors (moisture, soil reaction, and soil richness in mineral nitrogen) and form pretty compact environmental spaces: within each syntaxon, numerical values of the above factors, expressed in score points, normally vary within a narrow range. Regression analysis has established that the species richness of psammophytic communities depends statistically significantly only on the mineral nitrogen supply and soil moisture. Based on the statistical analysis results, the number of Pinus sylvestris plants of any age does not depend on the species richness in the community, total projective cover of the grass stand (excluding the Scots pine), separately calculated moss and lichen projective covers, and average numerical values of environmental factors identified by H. Ellenberg in the community. It is established that numbers of pine trees on study sites depend on only one factor: distance from the diaspora source determining the invasion possibility. The data on the phytocoenotic and floristic diversity of the psammophytic grass vegetation are to be incorporated into the unified database on the southern part of the nonchernozem zone of Russia to identify environmental and botanical–geographical features of this plant community type in the region.

Nestedness in Arbuscular Mycorrhizal Fungal Communities in a Volcanic Ecosystem: Selection of Disturbance-tolerant Fungi along an Elevation Gradient.

Arbuscular mycorrhizal (AM) fungi play a significant role in the establishment and resilience of vegetation in harsh environments, such as volcanic slopes, in which soil is frequently disturbed by ash falling and erosion. We characterized AM fungal communities associated with a pioneer grass in a volcanic slope based on the disturbance tolerance of the fungi, addressing the hypothesis that soil disturbance is a major ecological filter for AM fungi in volcanic ecosystems and, thus, fungi that are more tolerant to soil disturbance are selected at higher elevations (i.e. nearer to the crater). Paired soil-core samples were collected from the rhizosphere of Miscanthus sinensis between the vegetation limit and forest limit on a volcanic slope and used in a trap culture with M. sinensis seedlings, in which one of the paired samples was sieved to destroy hyphal networks (disturbance treatment), while the other was not (intact treatment). Seedlings were grown in a greenhouse for two months, and the roots were subjected to molecular analysis of fungal communities. AM fungal diversity decreased with increasing elevations, in which nested structure was observed. Community dissimilarity between the disturbed and intact communities decreased with increasing elevations, suggesting that communities at higher elevations were more robust against soil disturbance. These results suggest that AM fungi that are more tolerant to soil disturbance are more widely distributed across the ecosystem, that is, they are generalists. The wide distribution of disturbance-tolerant fungi may have significant implications for the rapid resilience of vegetation after disturbance in the ecosystem.

不同种植方式下两种草本营养元素对土壤厚度和水分减少的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 不同种植方式下两种草本营养元素对土壤厚度和水分减少的响应 DOI: 10.5846/stxb201709191673 作者: 作者单位: 三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院，重庆 400715,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院，重庆 400715,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院，重庆 400715,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院，重庆 400715,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院，重庆 400715,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院，重庆 400715,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31500399）；教育部第49批留学回国人员科研启动基金资助项目 Responses of nutrient elements of two grasses to the decline of soil thickness and/or water under different planting patterns Author: Affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Education,Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region,School of Life Sciences,Southwest University,Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Education,Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region,School of Life Sciences,Southwest University,,Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Education,Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region,School of Life Sciences,Southwest University,,Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Education,Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region,School of Life Sciences,Southwest University,Key Laboratory of Eco-environment in Three Gorges Reservoir Region(Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of life Sciences, Southwest University, Chongqing 400715, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了探究不同种植方式下草本植物对喀斯特"土层浅薄"和"岩溶干旱"生境的养分调节响应，选择苇状羊茅（Festuca arundinacea）和黑麦草（Lolium perenne）为研究材料，在盆栽水分控制条件下设置了2种土壤厚度[对照土壤厚度（TCK）和浅土（TS）]、2种水分处理[对照水分（WCK）和干旱（WD）]和2种种植方式（单种和混种），研究土壤厚度和水分减少对混种下两种草本植物元素含量、积累和分配的影响。结果表明：（1）与对照组（CK：TCKWCK）相比，在浅土组（S：TSWCK）、干旱组（D：TCKWD）和浅土+干旱组（SD：TSWD），苇状羊茅和黑麦草的地上和根系C和N含量在单种和混种下（浅土除外）显著增加，P含量和各部分元素积累量显著降低；而苇状羊茅的根系各元素分配比在3种低资源水平下（S、D、SD）由单种时增加转为混种时降低，而黑麦草的根系营养元素分配比在浅土中增加，但在干旱处理下减少。（2）在对照资源水平下（CK），混种后苇状羊茅的地上部分C含量、根系P含量、地上、地下和总的元素积累量和根系元素分配比显著高于单种，而在3种低资源水平下达到各参数在单种和混种下无显著差异。（3）在各资源水平下，混种后黑麦草各部分C、N、P的含量、积累量和根系元素分配比大体上与单种无显著差异。结果表明，在低资源水平下，苇状羊茅和黑麦草通过增加C和N元素含量表现出较强的资源获取和防御能力。在混种条件下，苇状羊茅能够通过调节自身元素的积累和分配来提高竞争力，而黑麦草保持相对恒定的策略来响应竞争。 Abstract:The karst ecosystems in southwest China are extremely fragile and vulnerable. The phenomenon of rocky desertification has become more serious, which causes karst soil to be scarcer and shallower. In addition, under the change of global rainfall pattern, the climate in SW China appears to have the trend of high temperature, low rainfall, and frequent occurrence of the continuous extreme drought events, which exacerbates the frequency and intensity of karst drought. Plants in karst regions have strong morphological plasticity and physiological regulation ability to minimize the impact of adverse environmental factors, such as shallow soil and drought. Meanwhile, in order to maximize the use of limited resources, plants in karst regions may have some ecological niche differentiation to reduce the inhibition of resource limitation on co-existence species. The nutritional characteristics play an important role in plant growth and physiological regulation, and might reveal clues about the adaptive and competitive mechanisms of plants in karst habit with shallow soil and karst drought. The gramineous perennial grass, Festuca arundinacea, is a deep-rooted plant as the root can be up to 40 cm depth in soil, while Lolium perenne, with root depth up to 25 cm, is a shallow-rooted plant. These two species are both introduced as pioneer grasses for re-vegetation in karst regions due to their high drought resistance, barren-tolerance, strong ecological adaptability, high yield and good economic benefit. They effectively improve the local ecological environment and help to alleviate rural poverty. Therefore, we chose these two species to study the effects of decline of soil thickness and/or water on the nutrient element contents, accumulation and distribution under different planting patterns. In our study, three factors, namely soil thickness (TCK:15 cm, and TS:5 cm), water (WCK:120 mL/3 d and WD:36 mL/3 d), and planting pattern (monoculture and mixture) were designed in a full three-way randomized block design. The results showed that:(1) Compared with control group (CK:TCKWCK), the C and N contents in aboveground part, root, and whole plant of both species increased (except in shallow soil group, S:TSWCK), while the P contents and their accumulations decreased in the shallow soil group (S:TSWCK), drought group (D:TCKWD), and shallow soil plus drought group (SD:TSWD) both in monoculture and in mixture. The root nutrient distribution ratio of F. arundinacea increased in monoculture but decreased in mixture at three low resource levels (S, D, SD). The root nutrient distribution ratio of L. perenne increased in the shallow soil group, but decreased in the drought group. (2) The C content in aboveground part, P content in root, and their accumulations of each part and root nutrient distribution ratio of F. arundinacea were significantly higher in mixture than in monoculture at control resource level (CK), while there was no-significant difference between mixture and monoculture for above traits of F. arundinacea at low resources levels. (3) At all resource levels, there was no significant difference between monoculture and mixture for all the above traits of L. perenne. The results indicated that both species had higher absorbing-resource and defense abilities by increasing C and N contents at low resource levels. In mixed planting, F. arundinacea could improve its competitiveness by adjusting element accumulation and distribution, while L. perenne might maintain a constant strategy of nutrient regulation in response to competition. 参考文献 相似文献 引证文献

3-1-16 Molecular Analysis of Microbial Communities Associated with Roots of Pioneer Grass Miscanthus condensatus on Recent Miyake-jima Volcanic Deposits

3-1-16 Molecular Analysis of Microbial Communities Associated with Roots of Pioneer Grass Miscanthus condensatus on Recent Miyake-jima Volcanic Deposits

Linkage between root systems of three pioneer plant species and soil nitrogen during early reclamation of a mine site in Lusatia, Germany

In 2005, a 7‐ha artificial watershed (Chicken Creek) was built on a post mined landscape in Lusatia, Germany from sandy substrates of Pleistocene origin, commonly used in reclamation. The watershed was developed to investigate the initial phase of soil and ecosystem development under natural conditions. At this early stage, mineral nitrogen in young sandy soils is primarily limited and nitrogen fixing legumes become key components of natural succession. Local abundant pioneering legumes Lotus corniculatus and Trifolium arvense and one pioneer grass species Calamagrostis epigeios were investigated 5 years after watershed construction. In this study, we investigated the influence of spatial root and nodule distribution of these species on soil nitrogen accumulation. Soil, including roots, was sampled from field monoliths covered with the aforementioned plant species. Root systems of both legumes were mainly restricted to the upper 20 cm of soil, whereas roots of C. epigeios also developed strongly at greater depths. A positive relationship was found, with higher plant densities associated with higher root densities which were associated with higher nodule densities for legumes and which were all associated with significantly higher soil nitrogen content relative to non‐vegetated areas. This research provides rare information on the role root systems of pioneer legumes play in soil nitrogen input in the early stage of soil and ecosystem development during revegetation by natural succession.

Drought resistance of native pioneer species indicates potential suitability for restoration of post-mining areas

Abstract. In order to test whether invasive exotic species, predominantly used for restoring post-mining areas in north-eastern Vietnam, may be replaced by ecologically superior native pioneer species, we conducted a drought stress experiment in a greenhouse. We hypothesized that juvenile individuals of four native pioneer tree and two native pioneer grass species have a drought resistance comparable to two exotic reference species. Our results confirm this hypothesis: even under drought, native trees had a higher biomass and root : shoot ratio than exotic trees, although their maximum relative elongation rate and biomass were reduced more strongly than for exotic trees with respect to well-watered conditions. Native grasses had a higher root length density and a similar drought-induced reduction of stomatal conductance compared to exotic trees. In spite of a higher biomass reduction, native grasses produced more biomass under drought in absolute terms. Notwithstanding that further investigations of other adverse environmental factors need to be performed, our results indicate with respect to drought resistance that native pioneer species are a potential alternative to exotic species for the ecological restoration of subtropical post-mining areas, which may accelerate secondary succession.

Soil mutualists modify priority effects on plant productivity, diversity, and composition

AbstractQuestionThe importance of priority effects on community assembly is well recognized, as is, increasingly, the role of environmental context in shaping those priority effects. Distinguishing the effects of soil nutrients and soil mutualists may be critical in the context of restoration, but remains poorly understood. Additionally, we asked whether pioneer species and soil conditions influenced trade‐offs or complementarities between vegetation production and species diversity.LocationPlant Growth Center, Montana State University, Bozeman, MT, US.MethodsUsing experimental seed addition in mesocosms, we investigated how the priority effects of different plant species influenced productivity, diversity and composition of the resulting plant community. We also experimentally manipulated soil nutrients and mycorrhizae to determine how they modified those priority effects.ResultsWe found that species‐specific priority effects of pioneers strongly governed the productivity, diversity and species composition of the resulting community. Pioneer grasses, one native and one non‐native species, both preempted light and space, prevented the colonization and growth of the subsequent community and restricted community dispersion (i.e. differences in species composition among mesocosms). By contrast, the pioneer forb species had little influence on the recruitment and establishment of the later colonizing species, and supported the assembly of divergent communities. We found evidence to suggest that amendments of soil mutualists, but not soil nutrients, modified the influence of one pioneer species on characteristics of the resulting community by enhancing community productivity and diversity in mesocosms with non‐native grass pioneers. Across all treatments, species diversity declined as vegetation production increased, indicating an overall trade‐off between productivity and diversity. However, relationships between productivity and diversity varied among pioneer treatments and mycorrhizal amendments.ConclusionsOur results emphasize important interactions between priority effects and the use of soil mycorrhizal amendments in restoration, as well as highlight how pioneer species and mycorrhizae influence potential trade‐offs between restoration objectives aimed at enhancing productivity vs species diversity.

Remotely Sensed Mapping of Ammophila spp. Distribution and Density at Cape Cod National Seashore

Timm, B.C.; Smith, S.M., and Greenspan, S.E., 2014. Remotely sensed mapping of Ammophila spp. distribution and density at Cape Cod National Seashore. Ammophila breviligulata and Ammophila arenaria are pioneer grass species that have been planted within and outside their natural ranges in efforts to stabilize mobile dune fields. While the presence of Ammophila spp. may be considered beneficial in some situations (e.g., for dune stabilization and storm surge protection), there are other cases where Ammophila spp. introductions have had negative ecological consequences (e.g., reduction in native plant and animal diversity, altered dune dynamics). Thus, it is important to be able to effectively map and monitor the distribution and density of these species. In this study, we constructed and assessed the accuracy of a fine-resolution (i.e. 1.0-m-pixel resolution) remote-sensing-based distribution and density map of Ammophila spp. throughout an extensive coastal dune ecosystem at Cape Cod National Seashore, United States. We achieved high classification accuracies for both the presence/absence and percent cover throughout our study area, indicating that this approach is an effective method to map and monitor Ammophila spp. in dune ecosystems.