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1.
Methods to reduce soil loss and associated loss of ecosystem functions due to land degradation are of particular importance in dryland ecosystems. Biocrusts are communities of cyanobacteria, lichens, and bryophytes that are vulnerable to soil disturbance, but provide vital ecosystem functions when present. Biocrusts stabilize soil, improve hydrologic function, and increase nutrient and carbon inputs. Methods to reestablish biocrust rapidly, when lost from ecosystems, have the potential to restore important dryland ecosystem functions and thereby increase probability of successful rehabilitation. The aim of this study was to identify habitat ameliorations to enhance the success of biocrust inoculation by: (1) reducing physiological stress on biocrusts and increasing resource availability (using shade, soil surface roughening, and watering), and (2) stabilizing mobile soils (using straw borders, three soil tackifiers [soil stabilizers], and a combination of shade, water, roughening, and tackifier). In the Great Basin Desert on the Utah Test and Training Range near Salt Lake City, we applied field‐harvested biocrust material to experimental plots on coarse‐ and fine‐textured soils with the top 2 cm of soil and biocrust removed. Habitat ameliorations were applied with and without biocrust addition. Shade provision increased biocrust cover 50% over controls. Biocrust cover and soil stability were 65% lower in straw border plots relative to controls. Soil tackifiers, alone and in combination with resource augmentation and stress reduction, did not improve cover and stabilization over inoculated controls. We found variability in recovery by time and between soil types. These results suggest plausible strategies to improve success of biocrust inoculation.  相似文献   

2.
Biological soil crusts are complex communities of organisms that develop on the top layer of dryland soils where they enhance important ecosystem services, including soil fertility and protection from erosion. Regrettably, a range of human activities such as cattle grazing, off‐road driving, hiking, and global warming result in significant deterioration of biocrust cover and their associated services. This scenario has prompted efforts to develop effective biocrust restoration strategies, which often involve the production of biocrust inoculum, both in greenhouse and in laboratory settings. Sometimes this inoculum is preconditioned in a process of “hardening” at considerable expense and effort in order to improve its fitness under harsh field conditions. But the positive effects of such hardening procedures have yet to be rigorously demonstrated. Here, we compared the growth performance of 20 cultured strains of biocrust cyanobacteria in outdoor tests on native soils as a function of preconditioning regimes consisting of increasingly high exposure to solar radiation, temperature and illumination daily variability, and recurrent wet‐dry cycles. Preconditioning improved performance in 13 out of 20 strains, particularly among pioneer crust‐forming Microcoleus spp. (eight out of eight). Improvements were variable among heterocystous strains (three out of four Scytonema spp., two out of four Tolypothrix spp., and none out of four Nostoc spp.). Based on these results, we recommend the inclusion of preconditioning treatments to increase inoculum survival rate and speed of cyanobacterial biocrust recovery in restoration of dryland soils.  相似文献   

3.
Features of the Loodsrecht Lakes, with emphasis on the main lake, are discussed with reference to restoration.Characteristics of the present situation are: (1) very low water transparency-Secchi-disc readings around 0.3 m occur in all seasons; (2) relatively small seasonal changes in sestonic matter; (3) important input of resuspended particles into the seston; (4) predominance of filamentous blue-green algae for most of the year; (5) relative scarcity of crustacean zooplankton, while rotifers are abundant; (6) poor development of littoral communities, and absence of benthic producers. The blue-green algae maintain high population density at very low growth rates: rates of loss are low. The zooplankton grazing rate is low due to inefficient filtering, but predation of larger crustaceans by fish may also be important. Studies on epipelon indicated that loss by deposition may be largely compensated by resuspension.Starting in 1984, the external phosphorus loading was markedly reduced. Results for 1984 and 1985 indicate that complementary measures are needed in order to improve water quality. Action should be directed towards increasing the phytoplankton turnover rates. Accelerated specific growth rate can be expected to accompany lower biomass, more successful competition by other algal groups, and enhancement of grazing pressure.Considering the shallowness of the system, promotion of littoral development and return of submerged vegetation may be important in establishing a new equilibrium of the system.  相似文献   

4.
Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring–fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our treatments except quantum yield, which was reduced in dark BSCs during one of three sample times and in Collema BSCs two of three sample times. There was more response to UV augmentation the second year when air temperatures were above average. Declines were seen in 21% of the measured variables, including quantum yield, chlorophyll a, UV‐protective pigments, nitrogenase activity, and extracellular polysaccharides. N additions had some negative effects on light and dark BSCs, including the reduction of quantum yield, β‐carotene, nitrogenase activity, scytonemin, and xanthophylls. N addition had no effects on the Collema BSCs. When N was added to samples that had received augmented UV, there were only limited effects relative to samples that received UV without N. These results indicate that the negative effect of UV and altered precipitation on BSCs will be heightened as global temperatures increase, and that as their ability to produce UV‐protective pigments is compromised, physiological functioning will be impaired. N deposition will only ameliorate UV impacts in a limited number of cases. Overall, increases in UV will likely lead to lowered productivity and increased mortality in BSCs through time, which, in turn, will reduce their ability to contribute to the stability and fertility of soils in dryland regions.  相似文献   

5.
Cyanobacteria are photosynthetic bacteria that form a fundamental part of soil biocrusts, enhance soil function and structure, and can promote plant growth. We assessed the potential of cyanobacteria as a seed bio‐primer for mine‐site restoration in an arid region in Western Australia, examining its effects on native plant growth and the characteristics of mine soil substrates used in dryland restoration. Cyanobacteria strains indigenous to the study region (Leptolyngbya sp., Microcoleus sp., Nostoc sp., and Scytonema sp.) were used to create an inoculant. Seeds of seven native plant species were bio‐primed with the inoculant, and their germination and growth assessed in a laboratory experiment. Seedling growth after bio‐priming was assessed in a glasshouse experiment for a subset of three species, in two different substrates (topsoil and mine waste). Soil properties related to soil function, e.g. total organic carbon, total nitrogen, and microbial activity, were also measured. Minor effects on germination were recorded with only significantly higher germination rates reported in E. gamophylla. Soil parameters were generally higher in topsoil than in mine waste, regardless of bio‐priming treatment. However, bio‐priming resulted in seedlings of four species producing longer radicles and/or shoots. For example, seedling root lengths of bio‐primed G. wickhamii were 57% larger than the control treatment (30.1 ± 4.3 and 13.0 ± 1.6 mm, respectively); and shoots of T. wiseana were 54% longer in the bio‐primed treatment (18.6 ± 1.6 mm) compared to the control (8.53 ± 1.4 mm). Overall, our results highlight that bio‐priming with cyanobacteria may improve plant growth for some species commonly used in dryland restoration.  相似文献   

6.
植被恢复对土壤碳氮循环的影响研究进展   总被引:1,自引:0,他引:1  
翁伯琦  郑祥洲  丁洪  王煌平 《生态学杂志》2013,24(12):3610-3616
植被恢复重建是治理水土流失的主要手段之一,能够有效地促进侵蚀土壤发育、提高土壤肥力、增强土壤微生物活性,进一步影响土壤碳氮循环.因此,植被的恢复重建过程对土壤有机碳库、氮库累积以及温室气体的排放具有一定作用.本文综述了植被恢复对土壤碳、氮循环过程的影响以及土壤质量与植被修复之间的协同效应,并提出了今后进一步研究的方向.对评价植被恢复在应对全球气候变化中所起的作用具有借鉴与参考价值,对促进土壤肥力改善和退化生态系统的恢复及可持续发展也有重要的现实意义.  相似文献   

7.
Mosses are an often‐overlooked component of dryland ecosystems, yet they are common members of biological soil crust communities (biocrusts) and provide key ecosystem services, including soil stabilization, water retention, carbon fixation, and housing of N2 fixing cyanobacteria. Mosses are able to survive long dry periods, respond rapidly to precipitation, and reproduce vegetatively. With these qualities, dryland mosses have the potential to be an excellent dryland restoration material. Unfortunately, dryland mosses are often slow growing in nature, and ex situ cultivation methods are needed to enhance their utility. Our goal was to determine how to rapidly produce, vegetatively, Syntrichia caninervis and S. ruralis, common and abundant moss species in drylands of North America and elsewhere, in a greenhouse. We manipulated the length of hydration on a weekly schedule (5, 4, 3, or 2 days continuous hydration per week), crossed with fertilization (once at the beginning, monthly, biweekly, or not at all). Moss biomass increased sixfold for both species in 4 months, an increase that would require years under dryland field conditions. Both moss species preferred short hydration and monthly fertilizer. Remarkably, we also unintentionally cultured a variety of other important biocrust organisms, including cyanobacteria and lichens. In only 6 months, we produced functionally mature biocrusts, as evidenced by high productivity and ecosystem‐relevant levels of N2 fixation. Our results suggest that biocrust mosses might be the ideal candidate for biocrust cultivation for restoration purposes. With optimization, these methods are the first step in developing a moss‐based biocrust rehabilitation technology.  相似文献   

8.
Biocrusts' functional importance and vulnerability to disturbance have motivated consistent interest in biocrust restoration, as well as a recent increase in research to cultivate biocrusts in laboratory and greenhouse settings for use in ecological restoration. As part of a sustainable approach to developing biocrust restoration, we argue that a complementary step is to improve and accelerate methods for salvaging biocrusts that would otherwise be destroyed in a forthcoming disturbance. The increasing rate and scale of disturbance pressures in drylands where biocrusts flourish means that the supply of salvageable biocrust and demand for that material in restoration greatly exceed the present cultivable supply. In this article we describe the state of knowledge for biocrust salvage, present a simple set of steps for conducting a salvage harvest, discuss risks and benefits when considering using salvage, and suggest future research directions to facilitate scaling up biocrust restoration using salvaged material. A focus on the use of salvaged biocrust as a restoration source may prove an important step to improve ecological restoration in notoriously difficult to restore dryland ecosystems.  相似文献   

9.
Biological soil crusts (biocrusts) are common and ecologically important members of dryland ecosystems worldwide, where they stabilize soil surfaces and contribute newly fixed C and N to soils. To test the impacts of predicted climate change scenarios on biocrusts in a dryland ecosystem, the effects of a 2–3 °C increase in soil temperature and an increased frequency of smaller summer precipitation events were examined in a large, replicated field study conducted in the cold desert of the Colorado Plateau, USA. Surface soil biomass (DNA concentration), photosynthetically active cyanobacterial biomass (chlorophyll a concentration), cyanobacterial abundance (quantitative PCR assay), and bacterial community composition (16S rRNA gene sequencing) were monitored seasonally over 2 years. Soil microbial biomass and bacterial community composition were highly stratified between the 0–2 cm depth biocrusts and 5–10 cm depth soil beneath the biocrusts. The increase in temperature did not have a detectable effect on any of the measured parameters over 2 years. However, after the second summer of altered summer precipitation pattern, significant declines occurred in the surface soil biomass (avg. DNA concentration declined 38%), photosynthetic cyanobacterial biomass (avg. chlorophyll a concentration declined 78%), cyanobacterial abundance (avg. gene copies g?1 soil declined 95%), and proportion of Cyanobacteria in the biocrust bacterial community (avg. representation in sequence libraries declined 85%). Biocrusts are important contributors to soil stability, soil C and N stores, and plant performance, and the loss or reduction of biocrusts under an altered precipitation pattern associated with climate change could contribute significantly to lower soil fertility and increased erosion and dust production in dryland ecosystems at a regional scale.  相似文献   

10.
Losses of grasslands have been largely attributed to widespread land-use changes, such as conversion to row-crop agriculture. The remaining tallgrass prairie faces further losses due to biological invasions by non-native plant species, often with resultant ecosystem degradation. Of critical concern for conservation, restoration of native grasslands has been met with little success following eradication of non-native plants. In addition to the direct and indirect effects of non-native invasive plants on beneficial soil microbes, management practices targeting invasive species may also negatively affect subsequent restoration efforts. To assess mechanisms limiting germination and survival of native species and to improve native species establishment, we established six replicate plots of each of the following four treatments: (1) inoculated with freshly collected prairie soil with native seeds; (2) inoculated with steam-pasteurized soil with native seeds; (3) noninoculated with native seeds; or (4) noninoculated/nonseeded control. Inoculation with whole soil did not improve seed germination; however, addition of whole soil significantly improved native species survival, compared to pasteurized soil or noninoculated treatments. Inoculation with whole soil significantly decreased reestablishment of non-native invasive Bothriochloa bladhii (Caucasian bluestem); at the end of the growing season, plots receiving whole soil consisted of approximately 30% B. bladhii cover, compared to approximately 80% in plots receiving no soil inoculum. Our results suggest invasion and eradication efforts negatively affect arbuscular mycorrhizal hyphal and spore abundances and soil aggregate stability, and inoculation with locally adapted soil microbial communities can improve metrics of restoration success, including plant species richness and diversity, while decreasing reinvasion by non-native species.  相似文献   

11.
秸秆覆盖量对红壤旱地棉花生长及土壤温度的影响   总被引:6,自引:0,他引:6  
为探索红壤旱地较适宜的秸秆覆盖量,采取随机区组大田试验,设置4个秸秆覆盖水平:S1为0 kg/hm~2、S2为4375 kg/hm~2,S3为8750 kg/hm~2和S4为13125 kg/hm~2,研究秸秆覆盖量对红壤旱地棉花产量、出苗率、株高、叶绿素含量和土壤温度的影响。结果表明:秸秆覆盖处理(S2—S4)较不覆盖处理(S1),一是提高棉花出苗率,差异极显著(P0.01);二是影响棉花生育后期的主茎生长速度,以S4效果最好;三是可明显促进棉花叶绿素含量的增加,且以S3和S4的效果较好;四是调节土壤温度,在8:00和20:00提高土壤温度,在14:00降低土壤温度,且日均地温变化幅度小,但随着土层的加深,调温作用逐渐减弱,整个覆盖期内日均温的差值与土壤深度具有高度的相关性;五是显著增加棉花产量,S2、S3和S4分别比S1高11.4%、35.9%和37.7%,差异极显著(P0.01),且随着覆盖量的增加,增产效果逐渐提高。综合来看,秸秆覆盖在改善红壤旱地棉花产量、出苗率、株高、叶绿素含量、调节土壤温度方面发挥着重要作用,且以8750—13125 kg/hm~2效果显著,是红壤旱地值得推广的栽培模式。  相似文献   

12.
土壤生物与土壤污染研究前沿与展望   总被引:11,自引:0,他引:11  
随着社会经济发展,人类生产活动对自然环境产生越来越广泛深刻的影响,土壤污染已成为危及生态系统稳定、农产品质量安全和人体健康的突出环境问题之一。重金属、有机污染化合物、病原菌及抗性基因等各类污染物大量进入土壤后,对土壤生物系统造成毒害作用,影响到土壤生态功能;另一方面,土壤生物如细菌、真菌、土壤动物等在一定程度上能够适应土壤污染,深刻影响着污染物在土壤中的迁移转化过程,在土壤污染修复中具有潜在重要作用。从土壤污染的生态毒理效应、土壤生物对土壤污染的响应与适应机制、污染土壤修复原理与技术等三方面综述了土壤生物与土壤污染相关研究前沿,展望了重点研究方向。  相似文献   

13.
As dryland degradation continues, it is increasingly important to understand how to effectively restore biocrust communities. Potential techniques include the addition of biocrust inoculum to accelerate biocrust recovery. Enhanced erosion typical of degraded environments creates a challenge for these approaches, due to loss by wind or water and burial by saltating particles. To retain and protect added inoculum, the inclusion of habitat‐amelioration techniques can improve recovery rates. This study tested three different types of inoculum (field‐collected, greenhouse‐cultivated, and laboratory‐cultivated biocrust) coupled with two treatments to augment soil stability and ameliorate habitat limitations: soil surface polyacrylamide additions and installation of straw barriers. This was done across two deserts (Great Basin and Chihuahuan) and separated into generally coarse‐ or finer‐textured soils in each desert, with results monitored for 3 years (2015, 2016, 2017). While the inoculum type, coupled with habitat ameliorations, occasionally enhanced biocrust growth across years and treatments, in other cases, it made no difference compared to natural recovery rates. Rather, the desert location and soil texture groupings were the most prominent factors in determining recovery trajectories. Recovery proportions were similar in the finer‐textured sites in both the Great Basin and the Chihuahuan deserts, while the coarser‐textured site in the Great Basin did show some recovery over time and the Chihuahuan coarser‐textured site did not. This study demonstrates the importance of understanding site potential and identifying key limitations to biocrust recovery for successful restoration projects.  相似文献   

14.
In arid and semiarid ecosystems, the potential threats of exotic invasive species are enhanced due to increasing human activities. Biological soil crusts (BSCs), acting as arid ecosystem engineers, may play an important role in preventing the establishment of exotic invasive plants. Our goal was to examine whether BSCs could inhibit the establishment of probable exotic plant species originating from adjacent grasslands located along the southeast edge of the Tengger Desert. In our study, we investigated the effects of three BSC types (cyanobacteria, lichen, and moss crusts) under two disturbance conditions (intact and disturbed) on the establishment of two exotic plant species (Ceratoides latens and Setaria viridis) using indoor experiments. We found both negative and positive effects of BSCs on the establishment of the two exotic plant species. Compared with the disturbed BSCs, the germination percentages of C. latens and S. viridis were reduced by 54% to 87% and 89% to 93%, respectively, in intact BSCs. In contrast, BSCs significantly promoted the height growth and aboveground biomass of the two exotic plant species (< .05) by enhancing the soil water and nutrient availability for the exotic plants. Our results confirm that BSCs strongly suppress the rapid expansion of exotic plant populations by inhibiting germination of seed with big size or appendages and have a weak inhibitory effect on exotic plant with small and smooth seeds. This may decrease the threat of propagation of exotic species. In the meantime, BSCs promote the growth of a few successful engraftment seedlings, which increased the beta diversity. Our work suggests that better understanding the two opposing effects of BSCs on the establishment of exotic plant species in different growth stages (germination and growth) is important for maintaining the health and stability of revegetated regions.  相似文献   

15.
以黄土丘陵区近20年的封禁地为研究对象,采用野外调查结合室内分析,研究了不同强度的踩踏干扰对半干旱生态系统下生物结皮盖度、有机碳、易氧化碳和有机碳矿化量、矿化速率的影响,并应用一级动力学方程模拟了踩踏干扰下各层次生物土壤结皮有机碳矿化潜力的变化特征.结果表明:干扰后藻结皮和藓结皮盖度呈现逐渐降低的趋势,干扰度间差异显著;与不干扰处理相比,藻结皮盖度降幅在264%~339%,藓结皮盖度降幅在46%~127%.与不干扰处理相比,干扰显著降低了生物结皮层有机碳含量,降幅在211%~300%,干扰度间差异不显著;干扰增加了生物结皮层易氧化碳含量,增加量在1.5~3.4 g·kg-1,30%、40%和50%干扰度处理与不干扰处理间差异显著.干扰显著增加了生物结皮层的有机碳累积矿化量,但未改变其日均矿化速率;40%干扰度下的累积矿化量较不干扰处理显著增加77%.干扰显著增加了生物结皮层的有机碳矿化潜力,对0~2和2~5 cm土层无显著影响;40%干扰度下有机碳矿化潜力较不干扰处理显著增加4.7 g·kg-1;主成分分析结果显示,有机碳、易氧化碳、累积矿化量、矿化速率可以解释生物结皮层土壤有机碳矿化潜力变化的76.7%.干扰可能是诱发研究区生物结皮层有机碳矿化潜力增加的因素之一.  相似文献   

16.
程才  李玉杰  张远东  高敏  李晓娜 《生态学报》2020,40(24):9234-9244
苔藓结皮是石漠化生态系统的重要地表覆被物,但其在土壤养分累积和元素循环过程中的作用尚不明确。以我国贵州典型喀斯特高原峡谷石漠化区-花江大峡谷两岸不同等级石漠化生境下的苔藓结皮及其覆被土壤为研究对象,研究了苔藓结皮覆被对土壤养分及生态化学计量特征的影响。结果表明:(1)苔藓结皮层养分含量显著高于下层土壤,结皮覆被土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)、碱解氮(AN)、速效磷(AP)、速效钾(AK)平均含量分别为25.95、3.05、1.00、5.10 g/kg和189.61、1.59、275.10 mg/kg,较无结皮覆被的裸土分别增加46.08%、26.50%、53.62%、20.25%、25.24%、110.47%和83.76%。(2)苔藓结皮覆被土壤C/N、C/K、P/K显著高于裸土,且随土层加深而递减;N/P显著低于裸土,且随土层加深而升高。(3)苔藓结皮覆被土壤养分恢复指数为33.16%—72.48%,呈现随石漠化等级升高而增加的趋势,中度和强度石漠化阶段较无石漠化阶段分别增加83.26%和118.58。本研究表明苔藓结皮能有效促进土壤养分累积,加速石漠...  相似文献   

17.
煤矿废弃地生态修复的土壤有机碳效应   总被引:6,自引:0,他引:6  
采煤使得植被和土壤遭到损毁破坏,导致原生态系统碳汇功能的急剧退化甚至完全丧失。采煤堆积的煤矸石可发生氧化自燃,是巨大的CO_2排放源。生态修复对减少矿区碳排放及减缓大气温室效应具有重要意义。分析了国内外煤矿废弃地生态修复后的土壤有机碳动态特征,修复模式、修复时间和修复措施对土壤有机碳及其活性组分的影响,总结了土壤固碳的主要影响因子。研究结果表明,土壤有机碳在人工植被修复和有机物添加后增加显著,且与修复时间成正比。煤矿废弃地通过采取适宜的生态修复措施,有很大的土壤固碳潜力。未来应加强团聚体固碳等土壤固碳机理和土壤活性有机碳等科学问题的研究,以期为退化区生态修复进程中土壤固碳功能提升提供参考。  相似文献   

18.
Restoration managers inoculate microorganisms to enhance soil function and improve restoration success, but the efficacy of these inoculations in real-world conditions is still unclear. We conducted a field experiment to test whether applying extruded seed pellets inoculated with native microbes affected soil properties related to ecosystem function in severely degraded mine soil. We found that inoculating with bacteria did not affect soil carbon, metabolic quotient (a measure of microbial stress), or basal respiration, but increased soil nitrogen by 75%, substrate-induced respiration by 147% and reduced carbon-to-nitrogen ratio by 44% compared to the control. This suggests that the bacteria inoculant contained free-living N fixers that increased the soil N content. Thus, inoculating with bacteria could supplement nitrogen fertilizers in degraded soils during soil restoration. However, we found that inoculating with a mix of bacteria and cyanobacteria did not affect any of the soil properties. This finding is counter to results in laboratory studies, suggesting that field tests are critical for understanding real-world outcomes of microbial inoculation. Finally, we found that soil microbial composition was changed by the inoculation with a mix of bacteria and cyanobacteria. None of the treatments significantly changed the diversity of soil microbial communities. Our data suggest that microbial inoculation could improve some aspects of ecosystem function and thus provide beneficial effects that might facilitate restoration of degraded sites.  相似文献   

19.
20.
Better understanding of the connection between aboveground plant communities and belowground soil organisms and processes has led to an explosion in recent research on the applications of this link to the field of ecological restoration. Research is only beginning to have the capacity to link soil organisms and specific ecosystem functions. Establishing general ecological principles of the role microbial communities have during ecological restoration is also still in its infancy. As such, the literature is at a critical point to generate a Special Feature that brings together novel approaches of linking soil and restoration to promote more regular inclusion and consideration of soil organisms and soil‐based processes in ecological restoration. In this special feature, we bring together nine research articles from different ecosystems that study the relationship between restoration activities, soil microbial communities, and soil properties. From these research articles, we describe two primary themes: (1) research on the impacts of ecosystem‐specific restoration activities on soil organisms and processes and (2) research testing methods of soil manipulation to improve restoration outcomes. We hope to inspire readers and restoration practitioners to consider soil microbes and soil processes in their research, restoration projects, and world views.  相似文献   

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