Fertile island effects across soil depths in drylands of the Tibetan Plateau

doi:10.21203/rs.3.rs-3583548/v1

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Fertile island effects across soil depths in drylands of the Tibetan Plateau

https://doi.org/10.21203/rs.3.rs-3583548/v1

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published 19 Mar, 2024

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Background and aims In arid regions, patches of vegetation serve a vital function in carbon and nutrient sequestration, fostering the emergence of 'fertile islands' within the soil beneath their canopies. However, the variation in the fertile island effects across soil depth remains an open question.

Methods To explore this, we sampled soils from two different layers (0-30 cm and 30-50 cm) within perennial vegetation patches and open areas across 54 drylands dispersed across the Tibetan Plateau. Our study focused on six key soil variables related to carbon, nitrogen, and phosphorus stocks, allowing us to assess the differences in fertile island effects at these varying depths.

Results Among six soil fertility parameters, organic carbon exhibited the most pronounced fertile island effect at both soil depths.. In the surface soil, the influence of vegetation in soil carbon content intensified with increasing precipitation seasonality and precipitation in the wettest quarter but declined with increasing temperature during the driest quarter. Conversely, in the deeper soil layer, the fertile island effect for nitrogen and phosphorus intensified with greater soil sand content and vegetation greenness.

Conclusions The fertile island effects responded differently to environmental factors at these two depths. These findings offer fresh and valuable insights into the interplay between environmental drivers and fertile island effects, a critical aspect of dryland ecosystems worldwide.

climate warming

precipitation of wettest quarter

relative interaction index

soil organic carbon

soil texture

Approximately 45% of the global landmass is composed of dryland regions, which collectively encompass around one-fifth of the global soil carbon stock (Huang et al., 2016; Pravalie, 2016). These regions display discrete clusters of discontinuous perennial vegetation, interspersed within an expanse of unvegetated soil (Eldridge, 1999; Valentin et al., 1999). Dryland vegetation patches possess the ability to seize and accumulate soil resources (carbon and nutrients) beneath their canopies and exhibit higher levels of biological functionality compared to nearby open areas lacking shrubs, leading to the emergence of what is commonly referred to as ‘fertile islands’ (de Graaff et al., 2014; Okin et al., 2004; Reynolds et al., 1999). These phenomena have received descriptions in arid regions worldwide (Ochoa-Hueso et al., 2018) and significantly impact the operation of ecosystems in dryland areas (Aguiar & Sala, 1999). Exploration of the phenomenon known as the fertile island typically emphasizes the surface level of soil (generally less than 30 cm deep), where soil fertility and biological activity are most pronounced in dryland ecosystems ((Holdo & Mack, 2014; Huang et al., 2012; Zhou et al., 2019). However, the depths to which shrub roots can extend are often beyond these limits, sometimes reaching up to 30 cm (He & Li, 2016). The biogeochemical cycling of soil matter, influencing soil carbon, nitrogen, and phosphorus contents is shaped by plant root exudates and communities of microorganisms (Coskun et al., 2017; Naylor et al., 2020). Moreover, soils at varying depths exhibit variations in their physical and chemical properties (Liu & Yang, 2022). As a result, when shrubs and trees contribute to the formation of fertile islands, we can anticipate that these effects will expand to encompass the underlying layers of soil. Surprisingly, existing research has not explored the potential effects of soil depth nor how these effects might be modulated by changing environmental factors across varying depths.

In this study, our objective was to evaluate the scale and principal drivers of the fertile island effect at two soil depths using the drylands of China's Tibetan Plateau as our study area. To achieve this, we conducted a comprehensive survey across 54 sites, encompassing the full spectrum of environmental conditions existing on the plateau. We systematically assessed six fertility variables from soil samples collected at two depths: beneath the canopies of perennial vegetation and in adjacent open areas lacking such vegetation.

We formulated two primary hypotheses, first that the fertile island effect would manifest at both soil depths, and second that the magnitude of this effect would vary with environmental factors affecting the surface and deeper soil layers. In particular, we expected that surface-level effects would be driven more by climatic factors whereas those at depth would be more closely associated with variation in soil properties. Our reasoning is that deeper soil layers typically exhibit a more stable microclimate and consistent moisture levels than the outermost stratum (Huang et al., 2023). Thus, fertile islands at the deeper layers would be shaped mainly by plant attributes and soil properties, with climatic factors playing a less prominent role.

Study sites

We conducted a survey in 54 dryland regions situated on the Tibetan Plateau in China in the stage marked by peak development (July to August) in both 2020 and 2021, focusing on areas where had the aridity index (AI, precipitation/potential evapotranspiration) less than 0.65 (UNEP 1997). The areas surveyed included 24 semiarid, 28 arid and two hyper arid sites (Fig. S1). The surveyed locations covered a wide range of aridity index values, from 0.02 to 0.41, average annual temperatures ranging between − 1.1 and 8.4°C, and average annual precipitation levels varying from 25 to 443 mm. Additionally, the elevation of these sites varied significantly, spanning from 1501 to 4778 m above sea level. The most prevalent vegetation species in the research site are Caroxylon passerinum, Reaumuria songarica, and Sympegma regelii; they are all non-leguminous shrubs that share a very similar plant size and life history.

Field survey

At every site, we established three quadrats measuring 10 m by 10 m. Within each quadrat, we collected four soil samples: one from the uppermost layer of soil (depth ranging from 0 to 30 cm) and one from the underlying layer of soil (depth ranging from 30 to 50 cm) in areas where vegetation was absent; and one each from the topsoil and subsoil beneath the overhead covering formed by the prevailing perennial plants, following the methodology outlined in Cai et al. (2023). Consequently, a combined sum of 12 samples of soil were gathered at every location.

The soil samples underwent filtration using a 2 mm mesh before being transported to further measurement and analysis. To measure the impact of fertile islands, we measured six soil fertility variables related to carbon, nitrogen, and phosphorus, including total carbon, organic carbon, inorganic carbon, total nitrogen, organic nitrogen, total phosphorus (Cai et al., 2023). We measured total carbon, total nitrogen, and organic carbon utilizing an elemental analyzer manufactured by Elementar (Vario MACRO Cube model from Germany). Soil inorganic carbon can be calculated as the discrepancy between total carbon and organic carbon. An auto-flow injection system for analysis (manufactured by Skalar, located in Breda, Netherlands) was employed to quantify levels of inorganic nitrogen. Soil organic nitrogen can be calculated as the discrepancy between total nitrogen and inorganic nitrogen. The soil total phosphorus was quantified using the molybdate-blue colorimetric method as described by Mehlich in 1984 (Mehlich, 1984). The soil sand content of each soil sample was determined using the Mastersizer 2000 instrument (Malvern, UK). We utilized a pH meter (Alalis, PH400, America) to determine the pH level in a slurry consisting of 10 grams of air-dried soil mixed with 25 milliliters of distilled water.

The climatic data of the 54 sites was obtained from WorldClim (https://worldclim.org/), where the spatial resolution is set at 1 km (Fick & Hijmans, 2017) and included 19 bioclimatic variables. From these we selected three (mean temperature of driest quarter, precipitation seasonality, precipitation of wettest quarter) that had relatively low correlation (< 0.6, Table S1) and are associated with the fertile island effect. The normalized difference vegetation index (NDVI) has been extensively utilized for assessing the growth and productivity of vegetation (Ye et al., 2019). We downloaded NDVI data from the National Tibetan Plateau Data Center (https://data.tpdc.ac.cn/en) (Gao et al., 2023). The temporal resolution of the NDVI data covers a period of 16 days spanning from 2000 to 2022, and its spatial resolution is set at 250 m. We extracted the average of the monthly maximum NDVIs of 2000–2022 as a proxy of the growing season vegetation.

Quantifying the fertile island effect

The relative interaction index (RII) (Armas et al., 2004) was employed to assess the extent of the fertile island effect for every soil fertility variable. The RII is a measure of the relative difference between shrub patches and inter-patch open areas for each measured variable. It is calculated using the following formula:

\({{\left( {{X_s} - {X_u}} \right)} \mathord{\left/ {\vphantom {{\left( {{X_s} - {X_u}} \right)} {\left( {{X_s}+{X_u}} \right)}}} \right. \kern-0pt} {\left( {{X_s}+{X_u}} \right)}}\)

The X_s and X_u represent the soil fertility variable of interest measured beneath the foliage of shrubs (s) and in a unvegetated area (u), correspondingly. This index has a scale of -1 to 1, where RII values > 0 indicate the presence of enhanced soil fertility beneath the shrub canopy (i.e., indicating a fertile island effect for specific soil fertility variables). This index enabled us to eliminate the impact of uncontrollable factors across different sites that may influence soil fertility in the sampled areas, but are unrelated to the extent of the fertile island effect (Ochoa-Hueso et al., 2018). The RII was determined for both surface and subsurface soils.

Statistical analyses

We compared the RII differences between the two soil depths, using the grouped t-test in the “ggpubr” package (Kassambara, 2018) of R 4.2.2. We used the Duncan test to analyze RII differences among the six soil fertility variables in each soil layer, using the “agricolae” package (Mendiburu, 2023). We also explored the changes in RII across the environmental gradient (mean temperature of driest quarter, precipitation seasonality, precipitation of wettest quarter, soil sand content and NDVI) using linear regression. We further explored the indirect and direct impacts of environmental factors on fertile islands at both surface and subsurface depths by structural equation modelling (Grace, 2006). We selected environmental factors to develop a priori causal model that can be later subjected to empirical testing. We postulated that the fertile island effect could be influenced by climatic factors, which in turn affect soil and vegetation characteristics. We conducted structural equation modelling analyses using the “lavaan” R package (Rosseel, 2012).

Soil total nitrogen and carbon, organic nitrogen and carbon were significantly greater beneath plant canopies than open areas for both depths (Fig. 1). The fertile island effects of inorganic carbon were not significant at either depth, and that of total phosphorus was significant only in the uppermost layer of the soil (Fig. 1). In the uppermost layer, the fertile island effect of soil organic carbon (SOC) was the highest, while that of inorganic carbon was the lowest; the fertile island effects of total carbon and total phosphorus were higher than that of inorganic nitrogen but lower than that of SOC. Generally same pattern was detected in the subsurface layer, SOC exhibited the highest fertile island effect among the six fertility variables studied. The magnitudes of the fertile island effect between the two soil depths did not show a significant difference for any of the variables evaluated (paired t-test, Fig. 1).

When we analyzed the data with a focus on different soil depths, we observed noteworthy variations in the fertile island effects. Specifically, there were six significant fertile island effects observed in the topsoil, whereas only three in the subsurface. For example, within the surface layer, the fertile island effects for total and inorganic carbon increased with higher precipitation levels during the wettest quarter, but there was no effect was in the deeper layers (Fig. 2a, 2b). For total and organic carbon, the fertile island effect declined with greater precipitation seasonality in the surface soils but remained unchanged at depth (Fig. 2c, 2d). Furthermore, the fertile island effects for total and inorganic carbon decreased with increasing temperature during the driest quarter in the surface soils but did not change at depth (Fig. 2e, 2f). In the deeper soil layer, the fertile island effects for total and organic nitrogen increased with increasing soil sand content, but there was no effect in the surface soils (Fig. 2g, 2h). Finally, the fertile island effect for total phosphorus increased significantly with greater NDVI, but this effect was only observed at depth (Fig. 2i).

Our structural equation models confirmed the direct positive effect of precipitation seasonality and soil sand content on the fertile island effect for organic carbon in the topsoil (Fig. 3a) but not in the underlying (Fig. 3b) layers. Our model suggests an indirect, weak suppressive effect of precipitation in the wettest quarter on the fertile islands in the surface layer via a negative association with soil sand content, but this was not apparent at deeper soil depths (Fig. 3b). NDVI exhibited a direct positive impact on the fertile islands of total phosphorus in the subsurface (Fig. 3d), but not the surface (Fig. 3c), layer. Precipitation in the wettest quarter and precipitation seasonality had indirectly positive effects (via NDVI) on the fertile island of total phosphorus in the subsurface (Fig. 3d), but not the surface layer (Fig. 3c).

Fertile island effects have rarely been compared between soil depths (Cao et al., 2021), particularly across large environmental gradients, despite the fact that effects may vary between different depths. In our study we showed strong fertile island effects at 54 dryland sites across the Tibetan Plateau but no differences between the two soil depths examined. We also demonstrated that the extent of the fertile island effect varied greatly among different soil fertility variables, with soil organic and inorganic carbon showing the highest and lowest effects at both depths, respectively. Overall, it is clear that our dryland shrub species have the capacity to accumulate carbon and nutrients at both the soil surface and at depth. The primary contributor of soil organic carbon to the soil is derived from plant litter (Dove et al., 2019). Plant roots additionally provide readily available exudates to nourish soil microbes, promoting their proliferation and conversion into organic carbon within the soil (Huang et al., 2000; Sokol & Bradford, 2019; Villarino et al., 2021). Therefore, it is not unexpected that we found a greater quantities of soil organic carbon beneath the plant canopies than the open areas. Carbonates formed during weathering are a major source of inorganic carbon in dryland ecosystems (Pan & Guo, 1999). Hence, changes in soil inorganic carbon were less affected by plants and that the fertile island effect was the lowest (Fig. 1).

In the surface layer, we observed a notable increase in the fertile island effects for soil organic carbon as precipitation seasonality increased. The surface soil layer experiences more rapid fluctuations in water conditions, i.e., it is frequently wet and dries out faster than to the deeper soil layers (Ebrahimi & Or, 2015). These varying wet-dry cycles in the upper layer may lead to an elevated soil fungal-to-bacterial ratio, thereby enhancing the capacity of the soil to retain nutrients (Gordon et al., 2008; Tecon & Or, 2016). Our structural equation modelling further revealed that organic carbon affected by the fertile island effect was directly impacted by precipitation seasonality. This link may be attributed to the structural and functional alterations that occur in microbial communities in response to wet-dry alternations (Gordon et al., 2008; Tecon & Or, 2016). We noted that the fertile island effects of total carbon increased with rising precipitation in the wettest quarter and increasing precipitation seasonality, but decreased with higher temperatures during the driest quarter. Greater precipitation seasonality appeared to intensify the magnitude of the fertile island effects for soil organic carbon, subsequently influencing the fertile island effects of total carbon. Moreover, the fertile island effect for inorganic carbon increased with increasing precipitation during the wettest quarter, but decreased with increasing temperature of the driest quarter. Higher precipitation levels in dryland soils tend to increase soil water content and microbial biomass (Manzoni et al., 2014; Nielsen & Ball, 2015; Sierra et al., 2017). Microorganisms, under these conditions, effectively decompose organic acids and matter into carbonate minerals, which ultimately contribute to inorganic carbon in the soil (Ferdush & Paul, 2021). The study area experiences an average temperature below freezing during the driest quarter, and snow cover provides thermal insulation that retards microbial metabolic activity. However, increasing temperatures, frequent freeze-thaw cycles and greater temperature fluctuations can have detrimental effects on surface soil microorganisms, ultimately inhibiting the organic carbon mineralization process into inorganic carbon (Campbell et al., 2005).

In the underlying layer of soil, it was observed that the fertile island effect for nitrogen increased with higher soil sand content, while the effect for phosphorus trended upwards with increasing vegetation greenness. In these deeper soil layers, the availability of oxygen is comparatively lower than in the surface layer, and the carbon substrate remains relatively stable, which limits the decomposition of carbon (Wang et al., 2022). Additionally, temperatures in deeper soil layers are less influenced by atmospheric temperature fluctuations compared to surface depths, which makes the fertile island effect of soil carbon less sensitive to climatic factors at this depth. In open areas, as soil sand content increases, the adsorption of nitrogen compounds by clay is inhibited, hindering the nitrogen mineralization process and resulting in reduced nitrogen content (Li et al., 2022). Furthermore, soils containing a greater proportion of sand are prone to experiencing nitrogen loss due to elevated levels of leaching and runoff (Dai et al., 2022; Zhao et al., 2022). Plants are the primary conduits for nitrogen entry into the soil (Chen et al., 2021). In areas with vegetation cover, plants act to reduce soil nitrogen loss through leaching and runoff (von Felten et al., 2009). Additionally, plant leaf and root litter make up a substantial source of soil organic nitrogen (Chen et al., 2022). Abundant nutrients derived from plants and the creation of diverse microbial habitats within plant communities can contribute to the promotion of soil microbial biomass and activity, leading to an acceleration in both nitrogen mineralization and immobilization rates (Hooper & Vitousek, 1998; Zak et al., 2003). These factors contribute to the observed increase in soil nitrogen content differences between subcanopy areas and bare sections. Consequently, the fertile island effect for total nitrogen and organic nitrogen exhibited an increase with coarser soil texture.

In the deeper soil layer, the fertile island effect for total phosphorus significantly increased with a rise in the value of the NDVI. A higher NDVI typically indicates greater vegetation productivity (Santin-Janin et al., 2009) and, consequently, greater litter production. Our findings are likely attributed to the buildup of plant debris in the soil beneath plant canopy, resulting in the release of phosphorus when this organic material decomposes. The presence of organic substances may result in the liberation of organic acids (Shan et al., 2008), which can potentially diminish the capacity of soil particles to retain phosphorus (Dossa et al., 2008; Ge et al., 2019), thereby enhancing the availability of extractable phosphorus (Yao et al., 2019). Furthermore, owing to the deep root distribution of shrubs, phosphorus accumulation may occur in the deeper soil layers.

Our findings indicate that the fertile island effects in surface and subsurface soil depths are of similar magnitude across Tibetan Plateau drylands, at least under the shrub species that we assessed. However, different environmental factors regulated the fertile islands in surface and subsurface soil depths. The influence of climatic factors (precipitation of wettest quarter, precipitation seasonality, and temperature of driest quarter) on the fertile island effect was primarily evident in the soil surface layer. Increasing precipitation seasonality may strengthen the fertile islands effect of soil carbon in the surface layer, while climate warming may reduce this fertile island effect. In deeper soil layers, the fertile island effect is regulated by vegetation and soil texture, suggesting the importance of vegetation in redistributing nutrients in deeper soils. Our findings offer fresh perspectives on the variations in crucial factors influencing the fertility of islands at different depths, which is a significant characteristic observed in dryland ecosystems across the globe.

Funding

This work was financially supported by the Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0305), the Fundamental Research Funds for the Central Universities (lzujbky-2022-ct01). Fernando T. Maestre has received research support from the University of Alicante (UADIF22-74 and VIGROB22-350) and the Spanish Ministry of Science and Innovation (PID2020-116578RB-I00).

Competing Interests

The authors have no relevant financial or non-financial interests to disclose.

Author Contributions

Jiansheng Ye designed the research. Tao Ma, Tenglong Hu and Wenbin Ke collected the samples and conducted laboratory analyses. Tao Ma, Jiansheng Ye, Fernando T. Maestre and David J. Eldridge wrote the manuscript. All authors read and approved the final manuscript.

Data Availability

The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.

Aguiar M, Sala OE (1999) Patch structure, dynamics and implications for the functioning of arid ecosystems. Trends Ecol Evol 14:273–277. https://doi.org/10.1016/s0169-5347(99)01612-2
Armas C, Ordiales R, Pugnaire FI (2004) Measuring plant interactions: A new comparative index. Ecology 85:2682–2686. https://doi.org/10.1890/03-0650
Cai QY, Wang XS, Ma T, Ye JS (2023) Soil fertility thresholds driven by sand content indicate drylands degradation phases on the Tibetan Plateau. Land Degrad Dev 34:3272–3280. https://doi.org/10.1002/ldr.4682
Campbell JL, Mitchell MJ, Groffman PM, Christenson LM, Hardy JP (2005) Winter in northeastern North America: a critical period for ecological processes. Front Ecol Environ 3:314–322. https://doi.org/10.2307/3868565
Cao Y, Su Y, Huang G, Li Y (2021) Soil texture modulates the intensity of fertile islands through affecting the distribution of shrub fine roots. J Arid Environ 189:104503. https://doi.org/10.1016/j.jaridenv.2021.104503
Chen X, Chen HYH, Searle EB, Chen C, Reich PB (2021) Negative to positive shifts in diversity effects on soil nitrogen over time. Nat Sustain 4:225–232. https://doi.org/10.1038/s41893-020-00641-y
Chen X, Feng J, Ding Z, Tang M, Zhu B (2022) Changes in soil total, microbial and enzymatic C-N-P contents and stoichiometry with depth and latitude in forest ecosystems. Sci Total Environ 816:151583. https://doi.org/10.1016/j.scitotenv.2021.151583
Coskun D, Britto DT, Shi WM, Kronzucker HJ (2017) How Plant Root Exudates Shape the Nitrogen Cycle. Trends Plant Sci 22:661–673. https://doi.org/10.1016/j.tplants.2017.05.004
Dai LJ, Ge JS, Wang LQ, Zhang Q, Liang T, Bolan N, Lischeid G, Rinklebe J (2022) Influence of soil properties, topography, and land cover on soil organic carbon and total nitrogen concentration: A case study in Qinghai-Tibet plateau based on random forest regression and structural equation modeling. Sci Total Environ 821. https://doi.org/10.1016/j.scitotenv.2022.153440
de Graaff MA, Throop HL, Verburg PSJ, Arnone JA, Campos X (2014) A Synthesis of Climate and Vegetation Cover Effects on Biogeochemical Cycling in Shrub-Dominated Drylands. Ecosystems 17:931–945. https://doi.org/10.1007/s10021-014-9764-6
Dossa EL, Bakam J, Kkouma M, Sene M, Kizito F, Dick RP (2008) Phosphorus Sorption and Desorption in Semiarid Soils of Senegal Amended with Native Shrub Residues. Soil Sci 173:669–682. https://doi.org/10.1097/SS.0b013e3181893999
Dove NC, Stark JM, Newman GS, Hart SC (2019) Carbon control on terrestrial ecosystem function across contrasting site productivities: the carbon connection revisited. Ecology 100:e02695. https://doi.org/10.1002/ecy.2695
Ebrahimi A, Or D (2015) Hydration and diffusion processes shape microbial community organization and function in model soil aggregates. Water Resour Res 51:9804–9827. https://doi.org/10.1002/2015wr017565
Eldridge DJ (1999) Distribution and floristics of moss- and lichen-dominated soil crusts in a patterned Callitris glaucophylla woodland in eastern Australia. Acta Oecologica-International Journal of Ecology 20:159–170. https://doi.org/10.1016/S1146-609x(99)80029-0
Ferdush J, Paul V (2021) A review on the possible factors influencing soil inorganic carbon under elevated CO2. Catena 204. https://doi.org/10.1016/j.catena.2021.105434
Fick SE, Hijmans RJ (2017) WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas. Int J Climatol 37:4302–4315. https://doi.org/10.1002/joc.5086
Gao J, Shi Y, Zhang HY, Chen X, Zhang W, Shen W, Xiao T, Zhang Y (2023) China regional 250m normalized difference vegetation index data set (2000–2022). https://doi.org/10.11888/Terre.tpdc.300328. National Tibetan Plateau Data Center
Ge NN, Wei XR, Wang X, Liu XT, Shao MA, Jia XX, Li XZ, Zhang QY (2019) Soil texture determines the distribution of aggregate-associated carbon, nitrogen and phosphorous under two contrasting land use types in the Loess Plateau. CATENA 172:148–157. https://doi.org/10.1016/j.catena.2018.08.021
Gordon H, Haygarth PM, Bardgett RD (2008) Drying and rewetting effects on soil microbial community composition and nutrient leaching. Soil Biol Biochem 40:302–311. https://doi.org/10.1016/j.soilbio.2007.08.008
Grace JB (2006) Structural Equation Modeling and Natural Systems. Cambridge University Press. https://doi.org/10.1017/CBO9780511617799
He JL, Li XG (2016) Potentilla fruticosa has a greater capacity to translocate phosphorus from the lower to upper soils than herbaceous grasses in an alpine meadow. Agric Ecosyst Environ 228:19–29. https://doi.org/10.1016/j.agee.2016.04.021
Holdo RM, Mack MC (2014) Functional attributes of savanna soils: contrasting effects of tree canopies and herbivores on bulk density, nutrients and moisture dynamics. J Ecol 102:1171–1182. https://doi.org/10.1111/1365-2745.12290
Hooper DU, Vitousek PM, EFFECTS OF PLANT COMPOSITION AND DIVERSITY ON NUTRIENT CYCLING (1998) Ecol Monogr 68:121–149. https://doi.org/10.1890/0012-9615(1998)068[0121:EOPCAD]2.0.CO;2
Huang G, Zhao XY, Li YQ, Cui JY (2012) Restoration of shrub communities elevates organic carbon in arid soils of northwestern China. Soil Biol Biochem 47:123–132. https://doi.org/10.1016/j.soilbio.2011.12.025
Huang J, Yu H, Guan X, Wang G, Guo R (2016) Accelerated dryland expansion under climate change. Nat Clim Change 6:166–171. https://doi.org/10.1038/nclimate2837
Huang W, Kuzyakov Y, Niu S, Luo Y, Sun B, Zhang J, Liang Y (2023) Drivers of microbially and plant-derived carbon in topsoil and subsoil. Glob Change Biol. https://doi.org/10.1111/gcb.16951
Huang ZQ, Liao LP, Wang SL (2000) Allelopathy of phenolics from decomposing stump-roots in replant Chinese fir woodland. J Chem Ecol 26:2211–2219. https://doi.org/10.1023/A:1005580718765
Kassambara A (2018) ggpubr:“ggplot2” based publication ready plots (Version 0.1. 7). Obtido desde https://CRAN.R-project.org/package=ggpubr
Li HC, van den Bulcke J, Kibleur P, Mendoza O, De Neve S, Sleutel S (2022) Soil textural control on moisture distribution at the microscale and its effect on added particulate organic matter mineralization. Soil Biology & Biochemistry 172. https://doi.org/10.1016/j.soilbio.2022.108777
Liu YXY, Yang YP (2022) Detecting a Declining Trend of Multidepth Soil Moisture Over the Mongolian Plateau From 1950 to 2020 Using ERA5-Land Reanalysis Datasets. Ieee Access 10:95509–95526. https://doi.org/10.1109/Access.2022.3204780
Manzoni S, Schaeffer SM, Katul G, Porporato A, Schimel JP (2014) A theoretical analysis of microbial eco-physiological and diffusion limitations to carbon cycling in drying soils. Soil Biol Biochem 73:69–83. https://doi.org/10.1016/j.soilbio.2014.02.008
Mehlich A (1984) Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant. Commun Soil Sci Plant Anal 15:1409–1416. https://doi.org/10.1080/00103628409367568
Mendiburu F (2023) d agricolae: Statistical Procedures for Agricultural Research. https://CRAN.R-project.org/package=agricolae
Naylor D, Sadler N, Bhattacharjee A, Graham EB, Anderton CR, McClure R, Lipton M, Hofmockel KS, Jansson JK (2020) Soil Microbiomes Under Climate Change and Implications for Carbon Cycling. Annu Rev Environ Resour 45 45:29–59. https://doi.org/10.1146/annurev-environ-012320-082720
Nielsen UN, Ball BA (2015) Impacts of altered precipitation regimes on soil communities and biogeochemistry in arid and semi-arid ecosystems. Glob Change Biol 21:1407–1421. https://doi.org/10.1111/gcb.12789
Ochoa-Hueso R, Eldridge DJ, Delgado-Baquerizo M, Soliveres S, Bowker MA, Gross N, Le Bagousse-Pinguet Y, Quero JL, Garcia-Gomez M, Valencia E, Arredondo T, Beinticinco L, Bran D, Cea A, Coaguila D, Dougill AJ, Espinosa CI, Gaitan J, Guuroh RT, Maestre FT (2018) Soil fungal abundance and plant functional traits drive fertile island formation in global drylands. J Ecol 106:242–253. https://doi.org/10.1111/1365-2745.12871
Okin GS, Mahowald N, Chadwick OA, Artaxo P (2004) Impact of desert dust on the biogeochemistry of phosphorus in terrestrial ecosystems. Glob Biogeochem Cycles 18. https://doi.org/10.1029/2003gb002145. Article Gb2005
Pan G, Guo T (1999) Pedogenic carbonate of aridic soils in China and its significance in carbon sequestration in terrestrial systems
Pravalie R (2016) Drylands extent and environmental issues. A global approach. Earth Sci Rev 161:259–278. https://doi.org/10.1016/j.earscirev.2016.08.003
Reynolds JF, Virginia RA, Kemp PR, de Soyza AG, Tremmel DC (1999) Impact of drought on desert shrubs: Effects of seasonality and degree of resource island development. Ecol Monogr 69:69–106. https://doi.org/10.1890/0012-9615(1999)069[0069:Iodods]2.0.Co;2
Rosseel Y (2012) lavaan: An R package for structural equation modeling. J Stat Softw 48:1–36. https://doi.org/10.18637/jss.v048.i02
Santin-Janin H, Garel M, Chapuis JL, Pontier D (2009) Assessing the performance of NDVI as a proxy for plant biomass using non-linear models: a case study on the Kerguelen archipelago. Polar Biol 32:861–871. https://doi.org/10.1007/s00300-009-0586-5
Shan YH, Cai ZC, Han Y, Johnson SE, Buresh RJ (2008) Organic acid accumulation under flooded soil conditions in relation to the incorporation of wheat and rice straws with different C:N ratios. Soil Sci Plant Nutr 54:46–56. https://doi.org/10.1111/j.1747-0765.2007.00218.x
Sierra CA, Malghani S, Loescher HW (2017) Interactions among temperature, moisture, and oxygen concentrations in controlling decomposition rates in a boreal forest soil. Biogeosciences 14:703–710. https://doi.org/10.5194/bg-14-703-2017
Sokol NW, Bradford MA (2019) Microbial formation of stable soil carbon is more efficient from belowground than aboveground input. Nat Geosci 12:46–53. https://doi.org/10.1038/s41561-018-0258-6
Tecon R, Or D (2016) Bacterial flagellar motility on hydrated rough surfaces controlled by aqueous film thickness and connectedness. Sci Rep 6. https://doi.org/10.1038/srep19409
Valentin C, d'Herbes JM, Poesen J (1999) Soil and water components of banded vegetation patterns. CATENA 37:1–24. https://doi.org/10.1016/S0341-8162(99)00053-3
Villarino SH, Pinto P, Jackson RB, Piñeiro G (2021) Plant rhizodeposition: A key factor for soil organic matter formation in stable fractions. Sci Adv 7:eabd3176. https://doi.org/10.1126/sciadv.abd3176
von Felten S, Hector A, Buchmann N, Niklaus PA, Schmid B, Scherer-Lorenzen M (2009) Belowground nitrogen partitioning in experimental grassland plant communities of varying species richness. Ecology 90:1389–1399. https://doi.org/10.1890/08-0802.1
Wang M, Guo X, Zhang S, Xiao L, Mishra U, Yang Y, Zhu B, Wang G, Mao X, Qian T, Jiang T, Shi Z, Luo Z (2022) Global soil profiles indicate depth-dependent soil carbon losses under a warmer climate. Nat Commun 13:5514. https://doi.org/10.1038/s41467-022-33278-w
Yao YF, Shao MG, Fu XL, Wang X, Wei XR (2019) Effects of shrubs on soil nutrients and enzymatic activities over a 0-100 cm soil profile in the desert-loess transition zone. CATENA 174:362–370. https://doi.org/10.1016/j.catena.2018.11.031
Ye JS, Delgado-Baquerizo M, Soliveres S, Maestre FT (2019) Multifunctionality debt in global drylands linked to past biome and climate. Glob Change Biol 25:2152–2161. https://doi.org/10.1111/gcb.14631
Zak DR, Holmes WE, White DC, Peacock AD, Tilman D (2003) PLANT DIVERSITY, SOIL MICROBIAL COMMUNITIES, AND ECOSYSTEM FUNCTION: ARE THERE ANY LINKS? Ecology. 84:2042–2050. https://doi.org/10.1890/02-0433
Zhao LQ, Wu XN, Huang N, Fu DG, Peng PY, Shang HY, Huang GN, Duan CQ (2022) Opposite responses of soil phosphorus fractions to two dominant species during early succession in subtropical phosphorus-enriched degraded mountain ecosystems. Catena 211. https://doi.org/10.1016/j.catena.2021.105962
Zhou Y, Boutton TW, Wu XB (2019) Woody plant encroachment amplifies spatial heterogeneity of soil phosphorus to considerable depth (vol 99, 136, 2018). Ecology 100. https://doi.org/10.1002/ecy.2860

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Fertile island effects across soil depths in drylands of the Tibetan Plateau

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