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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.
    
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   

3.
    
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   

4.
黄土丘陵区藓结皮人工培养方法试验研究   总被引：4，自引：0，他引：4       下载免费PDF全文
以陕北黄土丘陵区自然发育的藓结皮为繁殖材料,通过室内人工培养研究了藓类植物孢子繁殖法(孢子法)、植物碎片营养繁殖(断茎法)以及生物结皮团块粉碎(碎皮法)接种等不同方法对藓结皮形成发育的影响,并对不同培养温度和土壤含水量条件下的藓结皮生长发育进行比较分析.结果表明,(1)相同培养条件下,碎皮法接种有利于藓结皮盖度的形成,在20℃、光照5 230 lx、光周期12 h/d条件下,经80 d培养,藓结皮盖度、密度分别达到76%和59株/cm2,且显著高于其他方法.(2)不同的接种量对藓结皮形成发育影响显著,采用碎皮法,接种量在500～750 g/m2水平下藓结皮的盖度和藓类植物的密度生长较高.(3)温度显著影响藓结皮的形成和发育,在试验条件下,17℃有利于藓结皮盖度、藓类植株密度和株高的生长.(4)土壤含水量只有>60%田间持水量时才有藓结皮形成,当土壤含水量达到超饱和含水量,并在近地面处有水汽存在时则更有利于藓结皮的形成和发育.  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.
  总被引：2，自引：0，他引：2  
Biological soil crusts (biocrust) are microbial communities that develop at the soil surface of drylands and play an important role in erosion control and fertility. Soil surface disturbance from a broad range of natural and human processes (e.g. fire, livestock grazing, off‐road traffic) cause significant losses in biocrust cover and associated ecosystems services. Hence, biocrust restoration is emerging as an important intervention strategy to rehabilitate degraded dryland soils. In a multistep process, we designed protocols for the establishment of “microbial nurseries” to produce photosynthetic cyanobacterial inoculum for biocrust seeding at scale. We first report on the strategy for isolation, directly from the target site, of a large culture collection of cyanobacteria that included multiple representatives of the five most common biocrust taxa. After genetic pedigreeing of these isolates, we could select those that best matched field populations genetically for scale‐up cultivation. We then developed protocols for effective cyanobacterial biomass production to obtain sufficient inoculum. This was followed by conditioning treatments (hardening off) to preacclimate this inoculum to the stressful conditions expected in the field. Finally, we show that the inoculum obtained was fit to thrive in its original soil under natural outdoor conditions if sufficient water was available. We repeated this process successfully for four sites, two in the hot Chihuanuan desert and two in the cooler Great Basin Desert, and on two textural types of soils in each. The cyanobacterial biocrust nursery approach represents a versatile, viable, and safe tool for the rehabilitation of dryland soils.  相似文献   

7.
在黄土高原植被恢复初期,灌草植被显著降低了强降雨引起的水土流失,生物结皮与植被共同影响产流产沙过程,但它们的综合影响常被忽略。本研究通过室内人工模拟短历时、高强度的降雨试验,设置对照(无植被无生物结皮裸地)、草地、灌木、20%覆盖度生物结皮、草地+20%覆盖度生物结皮、灌木+20%覆盖度生物结皮、40%覆盖度生物结皮、草地+40%覆盖度生物结皮和灌木+40%覆盖度生物结皮9个处理,探究灌草植被和生物结皮对产流产沙过程的影响,并揭示其侵蚀动力机制。结果表明: 1)在降雨时间内对照组的产沙量始终最大,灌木、草本和生物结皮都具有良好的减蚀效益。2)灌木和草本植物处理产流量较对照组分别减少了21.9%和18.2%,具有促进土壤水分入渗的作用,而20%和40%盖度生物结皮处理的产流量分别增加了9.5%和17.4%,表现出抑制土壤水分入渗的作用,植被+生物结皮条件下,植被促进土壤水分入渗的作用大于生物结皮抑制土壤水分入渗的作用。3)草地+20%盖度生物结皮处理和所有40%盖度生物结皮处理的径流为缓流,其余处理为急流;各处理平均径流流速和径流动能显著小于对照组,而径流剪切力和阻力系数显著大于对照组,其中草地+40%盖度生物结皮处理的径流剪切力和阻力系数最大,较对照组分别增加了164.5%和213.8%,径流动能最小,较对照组减少了91.9%。综上,在植被生长恢复初期,保留适量生物结皮有益于防治水土流失和维持生态系统稳定,本试验条件下草地+40%盖度生物结皮处理的减蚀效果最好。  相似文献   

8.
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       下载免费PDF全文
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   

9.
    
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   

10.
    
In most drylands, biological soil crusts (biocrusts), an assemblage of lichens, bryophytes, fungi, green algae, and cyanobacteria, are critical to healthy ecosystem function. However, they are extremely sensitive to disturbance and attempts to facilitate their recovery have had variable success. In this study, we applied soil amendments designed to improve soil surface stability and accelerate biocrust recovery on an area disturbed by oil/gas exploration vehicles. Treatments included: (1) control (one time water only); (2) biocrust‐only: biocrust inoculum + nutrients in water; (3) polyacrylamide gels (which are known to stabilize soils) + biocrust inoculum + nutrients in water; (4) gypsum + biocrust inoculum + nutrients in water; and (5) saline (NaCl) solution + biocrust inoculum + nutrients in water. Only the NaCl treatment showed any effects on soil properties and these were only short term. These effects included an increase in soil strength and a reduction in soil aggregate stability, unsaturated hydraulic conductivity (Kh), and cyanobacterial biomass. The inoculated biocrust material failed to develop and even after 10 years, there was only a very low natural recolonization of the plots. These results show that inoculating soils or applying these levels of soil amendments does not guarantee recovery of soil stability or biocrust, and that some sites are unlikely to recover without assistance. Thus, there is a need for more research into ways to enhance soil stability and identify the factors limiting biocrust establishment.  相似文献   

11.
    
The artificial cultivation of moss biocrusts can accelerate the recovery of degraded arid lands and is closely related to moss productivity. Understanding the properties of inoculation materials on the regenerative capacity of mosses, in particular the effect of time limits on storage, has the potential to benefit the cultivation of artificial moss biocrusts. We investigated the vegetative regeneration and physiological characteristics of three desiccation‐tolerant mosses (Barbula unguiculata, Didymodon vinealis, and Didymodon tectorum) upon rehydration after periods of desiccation storage for 40, 89, 127, and 197 days. Regenerative capacity, represented by gametophyte vigor index, decreased with increased storage time. The greatest change in vegetative regeneration among storage times was observed in B. unguiculata, where the gametophyte vigor index decreased by 95.74% after 197 days of storage. Over the same period, there were smaller decreases in gametophyte vigor index of D. vinealis and D. tectorum of 42.17% and 13.30%, respectively. Malondialdehyde and soluble sugar increased with longer periods of storage time, while soluble protein content first increased, then decreased. Oxidation levels are important factors influencing the recovery of desiccation‐tolerant mosses. All three moss species regenerated after 197 days of storage, but regenerative capacity is dependent on species. For land managers, biocrust restoration can be facilitated by careful screening of suitable moss species, based on their capacity to regenerate new growth after extended periods of storage and selection of species based on variations in physiological characteristics.  相似文献   

12.
    
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   

13.
生物土壤结皮在中国西北干旱半干旱地区生态系统氮循环过程中发挥着至关重要的作用。气候模型预测西北地区未来将会经历降水模式的显著变化,而氮循环对这些变化特别敏感。然而,降水量的增加或减少会对生物土壤结皮氮循环过程产生哪些影响仍然不是很清楚。在宁夏荒漠草原生态修复野外定位观测研究区内,采用单因素完全随机试验设置降水量增减观测样地,借助宏基因组测序方法,对自然降水(CK)、减水 50%(DW)、增水 50%(AW)这 3 种处理条件下参与氮循环的微生物群落结构以及功能基因多样性对降水量变化的响应机制进行了分析。结果表明,藓结皮土壤参与氮循环的微生物群落结构组成主要包括细菌域的放线菌门(Actinomycetota)和假单胞菌门(Pseudomonadota)以及属于古菌域的亚硝化球菌门(Nitrososphaerota)。NMDS分析结果表明,不同降水条件下藓结皮土壤中参与氮循环的微生物类群存在显著差异,与氮循环相关的功能基因多样性也存在显著差异。narB基因的相对多度在AW条件下显著高于CK和DW,nasB基因的相对多度在AW条件下显著高于DW,nrfA基因的相对多度在DW条件下显著低于CK,pmoB/amoB基因的相对多度不论在DW还是AW条件下均显著高于CK。PERMANOVA分析结果表明,不同降水处理以及土壤有机质(SOM)可以分别解释参与氮循环微生物属水平组成差异的20.25%和14.12%以及参与氮循环功能基因多样性组成差异的26.23%和19.33%。藓结皮土壤微生物参与氮循环的过程中,受到降水量的显著影响,在未来降水量增加的背景下,藓结皮土壤中的化学性质能够保持动态平衡,同化性硝酸盐还原过程会增强。未来出现降水量减少的趋势,可能会导致藓结皮土壤中NH+4-N含量的增加,同时会限制异化性硝酸盐还原过程。无论减水还是增水条件下,都会促进氨氧化过程的增强。藓结皮微生物组响应降水量变化的过程中,其功能基因多样性的差异表明了微生物在氮循环功能方面的适应性调整。  相似文献   

14.
    
In some arid regions, rehabilitation of whole system N-fixation may be strongly facilitated by the recovery of populations of the lichen genus Collema . Identification of the limits to recovery of Collema in apparently suitable habitat should inform selection of rehabilitation techniques. We simultaneously tested the relative importance of three hypothetical limits to Collema recovery: active erosion, resource limitation, and propagule scarcity. We found that in our experimental system, active erosion had no effect on short-term establishment of Collema, whereas propagule addition did enhance recovery and microhabitat (a resource availability gradient) also exerted a strong influence. It is possible that attempts to improve N cycling via re-establishment of Collema might be best served by developing economical means of simulating moister, cooler microhabitats, e.g., sloping soil or creating partial shade, which would favor the establishment of naturally dispersed propagules, rather than introducing propagules.  相似文献   

15.
    
Agricultural activities have been expanding globally with the pressure to provide food security to the earth's growing population. These agricultural activities have profoundly impacted soil organic carbon (SOC) stocks in global drylands. However, the effects of clearing natural ecosystems for cropland (CNEC) on SOC are uncertain. To improve our understanding of carbon emissions and sequestration under different land uses, it is necessary to characterize the response patterns of SOC stocks to different types of CNEC. We conducted a meta-analysis with mixed-effect model based on 873 paired observations of SOC in croplands and adjacent natural ecosystems from 159 individual studies in global drylands. Our results indicate that CNEC significantly (p < .05) affects SOC stocks, resulting from a combination of natural land clearing, cropland management practices (fertilizer application, crop species, cultivation duration) and the significant negative effects of initial SOC stocks. Increases in SOC stocks (in 1 m depth) were found in croplands which previously natural land (deserts and shrublands) had low SOC stocks, and the increases were 278.86% (95% confidence interval, 196.43%–361.29%) and 45.38% (26.53%–62.23%), respectively. In contrast, SOC stocks (in 1 m depth) decreased by 24.11% (18.38%–29.85%) and 10.70% (1.80%–19.59%) in clearing forests and grasslands for cropland, respectively. We also established the general response curves of SOC stocks change to increasing cultivation duration, which is crucial for accurately estimating regional carbon dynamics following CNEC. SOC stocks increased significantly (p < .05) with high long-term fertilizer consumption in cleared grasslands with low initial SOC stocks (about 27.2 Mg ha−1). The results derived from our meta-analysis could be used for refining the estimation of dryland carbon dynamics and developing SOC sequestration strategies to achieve the removal of CO2 from the atmosphere.  相似文献   

16.
以腾格里沙漠东南缘固沙植被区和相邻天然植被区发育的藻类和藓类结皮为研究对象,采用不同规格的OTCs研究了冬季低温及短期模拟升温对其固氮活性的影响。结果表明:不同规格的OTCs装置冬季全天气温升温幅度在1℃左右,不同深度土层升温幅度更加明显,约为3.2℃;冬季试验期,湿润条件下藻类和藓类结皮均具有固氮活性,平均固氮活性分别为1.2×104和0.4×104nmolC2H4·m-2·h-1,藻类结皮的固氮活性显著高于藓类结皮(P<0.01);试验期藻类和藓类结皮的固氮活性均与培养期气温显著正相关(P<0.001),与试验前3d降水量也呈显著正相关(P<0.001)。低温湿润冷冻环境下,结皮生物体胞内冰晶形成而导致的固氮酶体系受损可能是造成冬季结皮固氮活性降低的主要原因,冬季升温能促进结皮固氮活性的提高。本研究表明,在未来全球变暖和降水格局变化背景下,冬季升温能促进生物土壤结皮对区域生态系统的氮贡献。  相似文献   

17.
    
Predicting the distribution of biocrust species, mosses, lichens and liverworts associated with surface soils is difficult, but climatic legacies (changes in climate over the last 20 k years) can improve our prediction of the distribution of biocrust species. To provide empirical support for this hypothesis, we used a combination of network analyses and structural equation modelling to identify the role of climatic legacies in predicting the distribution of ecological clusters formed by species of mosses, lichens and liverworts using data from 282 large sites distributed across 0.6 million km2 of eastern Australia. Two ecological clusters contained 87% of the 120 moss, lichen and liverwort species. Both clusters contained lichen, moss and liverwort species, but were dominated by different families. Sites where the air temperature increased the most over 20k years (positive temperature legacies) were associated with reductions in the relative abundance of species from the lichen (Peltulaceae and Teloschistaceae) and moss (Bryaceae) families (Cluster A species), greater groundstorey plant cover and lower soil pH. Sites where precipitation has increased over the past 20k years (positive precipitation legacy) were associated with increases in the relative abundance of lichen (Cladoniaceae, Lecideaceae and Thelotremataceae) and moss (Pottiaceae) families (Cluster B species) and lower levels of soil pH. Sites where temperatures have increased the most in the past 20k years suppressed the negative effects of plant cover on Cluster B by reducing plant cover. Increased intensity of grazing suppressed the negative effect of soil pH and the positive effect of soil carbon, on the relative abundance of Cluster B taxa. Finally, increasing temperature and precipitation legacies reduced the negative effect of soil pH on Cluster B. Understanding of the importance of climatic legacies improves our ability to predict how biocrust assemblies might respond to ongoing global environmental change associated with increasing land use intensification, increasing temperature and reduced rainfall.  相似文献   

18.
    
Drylands are unique among terrestrial ecosystems in that they have a significant proportion of primary production facilitated by non-vascular plants such as colonial cyanobacteria, moss, and lichens, i.e., biocrusts, which occur on and in the surface soil. Biocrusts inhabit all continents, including Antarctica, an increasingly dynamic continent on the precipice of change. Here, we describe in-situ field surveying and sampling, remote sensing, and modeling approaches to assess the habitat suitability of biocrusts in the Lake Fryxell basin of Taylor Valley, Antarctica, which is the main site of the McMurdo Dry Valleys Long-Term Ecological Research Program. Soils suitable for the development of biocrusts are typically wetter, less alkaline, and less saline compared to unvegetated soils. Using random forest models, we show that gravimetric water content, electrical conductivity, and snow frequency are the top predictors of biocrust presence and biomass. Areas most suitable for the growth of dense biocrusts are soils associated with seasonal snow patches. Using geospatial data to extrapolate our habitat suitability model to the whole basin predicts that biocrusts are present in 2.7 × 105 m2 and contain 11–72 Mg of aboveground carbon, based on the 90% probability of occurrence. Our study illustrates the synergistic effect of combining field and remote sensing data for understanding the distribution and biomass of biocrusts, a foundational community in the carbon balance of this region. Extreme weather events and changing climate conditions in this region, especially those influencing snow accumulation and persistence, could have significant effects on the future distribution and abundance of biocrusts and therefore soil organic carbon storage in the McMurdo Dry Valleys.  相似文献   

19.
李永刚  张元明 《生态学报》2023,43(4):1584-1595
藓结皮作为干旱区重要的地表覆盖物,主要呈斑块状分布,其大小能够明显改变土壤和藓类植物的含水量、蒸散量以及养分含量,对荒漠地表的稳定和碳循环具有重要作用。降雨是干旱荒漠区土壤水分的主要来源,能够直接影响藓结皮的生理活性,决定了藓结皮土壤的碳源-碳汇效应。然而不同大小藓结皮斑块碳通量对降雨的响应是否不同并不清楚。以古尔班通古特沙漠齿肋赤藓(Syntrichia caninervis Mitt.)斑块为研究对象,施加不同降雨量(0 mm、2 mm、5 mm、15 mm降雨),连续54 h测定不同大小藓结皮斑块(直径为：4.6 cm、5.6 cm、10 cm)碳通量。结果显示：(1)在2 mm和5 mm降雨量下,不同斑块大小藓结皮静碳交换速率连续54 h内的变化趋势相似,直径为4.6 cm和5.6 cm斑块累积碳通量呈负值,表现为碳固定,10 cm斑块则相反表现为碳释放,在15 mm降雨量下,不同斑块大小藓结皮碳通量均表现为碳释放,直径为10 cm的藓结皮斑块净碳交换速率随时间的变化趋势与直径5.6 cm和4.6 cm藓结皮斑块不同;(2)斑块大小和降雨量变化均显著影响藓结皮斑块碳通量,土壤含...  相似文献   

20.
大气降尘是矿区土壤重金属的主要来源,而生物结皮对大气降尘重金属有显著的富集作用。为探究不同类型生物结皮对大气降尘重金属的富集规律及其影响因子,选取宁东典型火电厂周边生物结皮广布区作为试验样地,3类生物结皮作为研究对象,并以临近裸土作为对照,对比分析了生物结皮富集大气降尘过程中土壤理化性质、酶活性及重金属含量的变化,采用相关分析、冗余分析和方差分解方法探讨了不同类型生物结皮的结皮层(A层)和层下土壤(B层)重金属含量与其土壤物理、化学性质及酶活性之间的关系。结果表明：燃煤烟尘是矿区大气降尘重金属污染的主要来源,涉及重金属元素包括Cd、Cr、Hg、Pb、Zn、As。生物结皮对源自大气降尘的重金属元素均具有显著的富集作用,且在不同演替阶段生物结皮间的富集规律完全一致：藓结皮>混生结皮>藻结皮;重金属综合污染指数评价结果显示：生物结皮对重金属具有表层富集效应,表现为A层污染程度高于B层。不同类型生物结皮A、B层综合污染指数存在显著差异,排序为：藓结皮>混生结皮>藻结皮;和对照相比,三类生物结皮均能通过富集大气降尘增加其A、B层养分和细颗粒物含量并改善土壤质地。方差分解结...  相似文献   

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