Edge and land-use effects on epiphytic lichen diversity in the forest-steppe ecotone of the Mongolian Altai

Epiphytic lichen diversity was studied in forests of Siberian larch (Larix sibirica) in the forest-steppe ecotone of the Mongolian Altai. These forests are utilized for livestock grazing, fuelwood collection and occasional logging by pastoral nomads. The density of nomad households in the proximity of the forests influences epiphytic lichen diversity more strongly than the position of sample trees in the forest interior or at the forest line to the steppe. This suggests that land use exerts a stronger effect on lichen diversity than the distinct gradient in microclimate between the forest interior and the forest edge. The co-occurrence of nitrophytes with anitrophytic acidophytes on a small spatial scale as well as higher N and Ca concentrations and pH values in the bark of larch trees at the forest edge than in the forest interior indicate that moderate livestock grazing increases the epiphytic lichen diversity due to an increase of the diversity of chemically different microhabitats. Preference of many lichen species (and of rare species in particular) for overmature and decaying trees suggests that logging and fuelwood collection has adverse effects on epiphytic lichen diversity. This adverse effect is likely to be more crucial for lichen diversity than the putatively positive effect of livestock grazing, since more lichens with a preference for old and decaying trees than for nitrogen-enriched bark were found. The present study is the first one investigating the impact of pastoral nomadism in Central Asia on epiphyte diversity.     

Forest edge-interior differentiation in the epiphytic lichen diversity of the forest steppe in the Khangai Mountains,Mongolia

Aims The effects of traditional land use by mobile livestock keepers on biodiversity in forest steppe ecotones are insufficiently studied. Epiphytes are an important part of forest plant diversity. Here we analyze differences in the diversity and composition of the epiphytic lichen vegetation between the edge and the interior of Siberian larch forests in the Khangai Mountains, western Mongolia, which are highly subdivided into patches. We asked whether the epiphytic lichen vegetation at the forest edge differs significantly from that in the interior, whether the edge is inhabited by more nitrophilous species than the interior and whether the density of nomad camps around the forest affects epiphytic lichen diversity.Methods Cover percentages of epiphytic lichen species were recorded from 20 trees per plot on 6 plots in the interior and 6 plots at the edge of Larix sibirica forests. The position of nomad summer camps was surveyed using Global Positioning System. Data were analyzed with pairwise significance tests, analysis of similarities, nonmetric multidimensional scaling and canonical correspondence analysis.Important findings The composition of the epiphytic lichen vegetation clearly differed between the two habitats, with more species being more frequent at the edge than in the interior. However, there was no difference in species richness (α-diversity). The epiphyte vegetation at the edge was more uniform and characterized by lower variation of tree-level α-diversity and lower β-diversity than in the interior. At the edge, only nitrophytic lichens were dominant, whereas in the interior, nitrophytes and acidophytes were among the dominant species. This pattern is probably attributable to the spatial heterogeneity of the intensity of forest grazing and was shown to be influenced by the density of nomad summer camps in the vicinity of the forests. Tree-level α-diversity increased with stem diameter, but high-diameter trees were rare. The results suggest that the present level of forest patchiness and the effect of forest grazing increases the diversity of epiphytic lichens on the landscape level, while logging of high-diameter trees reduces lichen diversity.     

Response of tree-ring width to climate warming and selective logging in larch forests of the Mongolian Altai

Aims The Mongolian Altai is an old settlement area, which is populated by pastoral nomads since 2000–3000 years. Forests in this region (at ca. 2300 m a.s.l.) are highly fragmented and border on steppe and alpine grasslands, which are used for mobile livestock husbandry. The climate in Central Asia is warming to levels clearly above the global average, which affects the vegetation. Furthermore, the transition from planned to market economy and the decollectivization of livestock 20 years ago has strongly changed land use practices in Mongolia, especially resulting in an increase in recent logging activities. We were interested in the question how climate warming and selective logging influence the annual stem growth and the stand structure.Methods The impact of climate and land use by the pastoral nomads on the annual stem increment of more than 1800 trees of Siberian larch (Larix sibirica) was analyzed. Different groups of trees with divergent growth trends depending on the social position and stand history were identified by non-metric multidimensional scaling and analysis of similarities. Long-term trends in the annual stem increment were analyzed by establishing separate regional growth curves for trees of different age classes.Important findings Instrumental climate data substantiate an increase of temperature by 2.1°C since 1940 at constant precipitation. Trees benefit from the increased temperatures. Climate–response analysis revealed that radial stem increment was promoted by the temperature in early summer, but also high precipitation in spring and in the year before tree-ring formation. Forest dynamics is also strongly influenced by anthropogenic activities. In addition to the natural forest dynamics, logging resulted in divergent growth trends within given age classes and habitats (forest interior and forest edge); overall, 22 groups of trees with different characteristics in the annual radial stem increment were identified. A tree-ring series-based reconstruction of logging intensity since 1935 suggests that moderate selective logging occurred throughout the study period. However, selective logging was strongly intensified after 1990 as the result of the breakdown of the Communist regime in Mongolia and the transition from centrally planned to market economy. Because tree stump densities showed that the ratio of felled to live trees was 2:1 in the interior or even 0.9:1 at the edges of the forests and most logging occurred during the past 20 years, it must be concluded that the forests of the Mongolian Altai are presently exploited far beyond the level of sustainability. A close correlation of the ratio of felled to live trees with the density of summer camps of pastoral nomads in the vicinity suggests that trees are primarily felled by the local population.     

Higher climate warming sensitivity of Siberian larch in small than large forest islands in the fragmented Mongolian forest steppe

Forest fragmentation has been found to affect biodiversity and ecosystem functioning in multiple ways. We asked whether forest size and isolation in fragmented woodlands influences the climate warming sensitivity of tree growth in the southern boreal forest of the Mongolian Larix sibirica forest steppe, a naturally fragmented woodland embedded in grassland, which is highly affected by warming, drought, and increasing anthropogenic forest destruction in recent time. We examined the influence of stand size and stand isolation on the growth performance of larch in forests of four different size classes located in a woodland‐dominated forest‐steppe area and small forest patches in a grassland‐dominated area. We found increasing climate sensitivity and decreasing first‐order autocorrelation of annual stemwood increment with decreasing stand size. Stemwood increment increased with previous year's June and August precipitation in the three smallest forest size classes, but not in the largest forests. In the grassland‐dominated area, the tree growth dependence on summer rainfall was highest. Missing ring frequency has strongly increased since the 1970s in small, but not in large forests. In the grassland‐dominated area, the increase was much greater than in the forest‐dominated landscape. Forest regeneration decreased with decreasing stand size and was scarce or absent in the smallest forests. Our results suggest that the larch trees in small and isolated forest patches are far more susceptible to climate warming than in large continuous forests pointing to a grim future for the forests in this strongly warming region of the boreal forest that is also under high land use pressure.     

Carbon pool densities and a first estimate of the total carbon pool in the Mongolian forest‐steppe

The boreal forest biome represents one of the most important terrestrial carbon stores, which gave reason to intensive research on carbon stock densities. However, such an analysis does not yet exist for the southernmost Eurosiberian boreal forests in Inner Asia. Most of these forests are located in the Mongolian forest‐steppe, which is largely dominated by Larix sibirica. We quantified the carbon stock density and total carbon pool of Mongolia's boreal forests and adjacent grasslands and draw conclusions on possible future change. Mean aboveground carbon stock density in the interior of L. sibirica forests was 66 Mg C ha^?1, which is in the upper range of values reported from boreal forests and probably due to the comparably long growing season. The density of soil organic carbon (SOC, 108 Mg C ha^?1) and total belowground carbon density (149 Mg C ha^?1) are at the lower end of the range known from boreal forests, which might be the result of higher soil temperatures and a thinner permafrost layer than in the central and northern boreal forest belt. Land use effects are especially relevant at forest edges, where mean carbon stock density was 188 Mg C ha^?1, compared with 215 Mg C ha^?1 in the forest interior. Carbon stock density in grasslands was 144 Mg C ha^?1. Analysis of satellite imagery of the highly fragmented forest area in the forest‐steppe zone showed that Mongolia's total boreal forest area is currently 73 818 km², and 22% of this area refers to forest edges (defined as the first 30 m from the edge). The total forest carbon pool of Mongolia was estimated at ~ 1.5?1.7 Pg C, a value which is likely to decrease in future with increasing deforestation and fire frequency, and global warming.     

Fine-scale distribution of the epiphytic lichen Usnea longissima on two even-aged neighbouring Picea abies trees

Abstract. Two neighbouring even-aged 130-yr old Picea abies trees in a homogeneous stand can differ substantially with respect to their epiphytic vegetation. Sampled branches from the canopy of one tree harboured 781 specimens of the old forest lichen Usnea longissima of which only 50 could be seen from the ground, whereas no U. longissima were found on its nearest neighbour. Usnea longissima was most abundant on branch tips in lower parts of the canopy on branch segments having the highest biomass of other alectorioid species. Trees with and without U. longissima showed a different pattern in their mineral composition, suggesting that a tree-specific difference in nutritional status might contribute to explain the patchy distribution of this lichen within seemingly homogeneous stands.     

Spatial patterns of gene expression in the extramatrical mycelium and mycorrhizal root tips formed by the ectomycorrhizal fungus Paxillus involutus in association with birch (Betula pendula) seedlings in soil microcosms

Functional compartmentation of the extramatrical mycelium of ectomycorrhizal (ECM) fungi is considered important for the operation of ECM associations, although the molecular basis is poorly characterized. Global gene expression profiles of mycelium colonizing an ammonium sulphate ((NH4)2SO4) nutrient patch, rhizomorphs and ECM root tips of the Betula pendula-Paxillus involutus association were compared by cDNA microarray analysis. The expression profiles of rhizomorphs and nutrient patch mycelium were similar to each other but distinctly different from that of mycorrhizal tips. Statistical analyses revealed 337 of 1075 fungal genes differentially regulated among these three tissues. Clusters of genes exhibiting distinct expression patterns within specific tissues were identified. Genes implicated in the glutamine synthetase/glutamate synthase (GS/GOGAT) and urea cycles, and the provision of carbon skeletons for ammonium assimilation via beta-oxidation and the glyoxylate cycle, were highly expressed in rhizomorph and nutrient patch mycelium. Genes implicated in vesicular transport, cytoskeleton organization and morphogenesis and protein degradation were also differentially expressed. Differential expression of genes among the extramatrical mycelium and mycorrhizal tips indicates functional specialization of tissues forming ECM associations.     

Fertilization effects on fineroot biomass, rhizosphere microbes and respiratory fluxes in hardwood forest soils

Fertilizer-induced reductions in CO(2) flux from soil ((F)CO(2)) in forests have previously been attributed to decreased carbon allocation to roots, and decreased decomposition as a result of nitrogen suppression of fungal activity. Here, we present evidence that decreased microbial respiration in the rhizosphere may also contribute to (F)CO(2) reductions in fertilized forest soils. Fertilization reduced (F)CO(2) by 16-19% in 65-yr-old plantations of northern red oak (Quercus rubra) and sugar maple (Acer saccharum), and in a natural 85-yr-old yellow birch (Betula allegheniensis) stand. In oak plots, fertilization had no effects on fine root biomass but reduced mycorrhizal colonization by 18% and microbial respiration by 43%. In maple plots, fertilization reduced root biomass, mycorrhizal colonization and microbial respiration by 22, 16 and 46%, respectively. In birch plots, fertilization reduced microbial respiration by 36%, but had variable effects on root biomass and mycorrhizal colonization. In plots of all three species, fertilization effects on microbial respiration were greater in rhizosphere than in bulk soil, possibly as a result of decreased rhizosphere carbon flux from these species in fertile soils. Because rhizosphere processes may influence nutrient availability and carbon storage in forest ecosystems, future research is needed to better quantify rhizo-microbial contributions to (F)CO(2).     

Complex effects of mammalian grazing on extramatrical mycelial biomass in the Scandes forest‐tundra ecotone

Mycorrhizal associations are widespread in high‐latitude ecosystems and are potentially of great importance for global carbon dynamics. Although large herbivores play a key part in shaping subarctic plant communities, their impact on mycorrhizal dynamics is largely unknown. We measured extramatrical mycelial (EMM) biomass during one growing season in 16‐year‐old herbivore exclosures and unenclosed control plots (ambient), at three mountain birch forests and two shrub heath sites, in the Scandes forest‐tundra ecotone. We also used high‐throughput amplicon sequencing for taxonomic identification to investigate differences in fungal species composition. At the birch forest sites, EMM biomass was significantly higher in exclosures (1.36 ± 0.43 g C/m²) than in ambient conditions (0.66 ± 0.17 g C/m²) and was positively influenced by soil thawing degree‐days. At the shrub heath sites, there was no significant effect on EMM biomass (exclosures: 0.72 ± 0.09 g C/m²; ambient plots: 1.43 ± 0.94). However, EMM biomass was negatively related to Betula nana abundance, which was greater in exclosures, suggesting that grazing affected EMM biomass positively. We found no significant treatment effects on fungal diversity but the most abundant ectomycorrhizal lineage/cortinarius, showed a near‐significant positive effect of herbivore exclusion (p = .08), indicating that herbivory also affects fungal community composition. These results suggest that herbivory can influence fungal biomass in highly context‐dependent ways in subarctic ecosystems. Considering the importance of root‐associated fungi for ecosystem carbon balance, these findings could have far‐reaching implications.     

An Analysis of Vegetation Restoration on Opencast Oil Shale Mines in Estonia

We compared four types of 30‐year‐old forest stands growing on spoil of opencast oil shale mines in Estonia. The stand types were: (1) natural stands formed by spontaneous succession, and plantations of (2) Pinus sylvestris (Scots pine), (3) Betula pendula (silver birch), and (4) Alnus glutinosa (European black alder). In all stands we measured properties of the tree layer (species richness, stand density, and volume of growing stock), understory (density and species richness of shrubs and tree saplings), and ground vegetation (aboveground biomass, species richness, and species diversity). The tree layer was most diverse though sparse in the natural stands. Understory species richness per 100‐m² plot was highest in the natural stand, but total stand richness was equal in the natural and alder stands, which were higher than the birch and pine stands. The understory sapling density was lower than 50 saplings/100 m² in the plantations, while it varied between 50 and 180 saplings/100 m² in the natural stands. Growing stock volume was the least in natural stands and greatest in birch stands. The aboveground biomass of ground vegetation was highest in alder stands and lowest in the pine stands. We can conclude that spontaneous succession promotes establishment of diverse vegetation. In plantations the establishment of diverse ground vegetation depends on planted tree species.     

Evidence for discontinuous water columns in the xylem conduit of tall birch trees

The continuity of the xylem water columns was studied on 17- to 23-m tall birch trees (trunk diameter about 23 cm; first branching above 10 m) all year round. Fifty-one trees were felled, and 5-cm thick slices or 2-m long boles were taken at regular, relatively short intervals over the entire height of the trees. The filling status of the vessels was determined by (i) xylem sap extraction from trunk and branch pieces (using the gas bubble-based jet-discharge method and centrifugation) and from trunk boles (using gravity discharge); (ii) ¹H nuclear magnetic resonance imaging of slice pieces; (iii) infusion experiments (dye, ⁸⁶Rb⁺, D₂O) on intact trees and cut branches; and (iv) xylem pressure measurements. This broad array of techniques disclosed no evidence for continuous water-filled columns, as postulated by the Cohesion–Tension theory, for root to apex directed mass transport. Except in early spring (during the xylem refilling phase) and after extremely heavy rainfall during the vegetation period, cohesive/mobile water was found predominantly at intermediate heights of the trunks but not at the base or towards the top of the tree. Similar results were obtained for branches. Furthermore, upper branches generally contained more cohesive/mobile water than lower branches. The results suggest that water lifting occurs by short-distance (capillary, osmotic and/or transpiration-bound) tension gradients as well as by mobilisation of water in the parenchymatic tissues and the heartwood, and by moisture uptake through lenticels.     

Changes in the chemical content of birch (<Emphasis Type="Italic">Betula pendula </Emphasis>Roth) leaves in the air polluted Krusne hory mountains

Analyses of birch leaves (Betula pendula Roth) sampled from trees in the air polluted Krusne hory mountains and Decin sandstone highlands were performed in 1995 and 1998. The results revealed a connection between reduction of air pollutants and overall decrease in sulphur and nitrogen content of the leaves. Simultaneously, in many stands an increase in calcium content and a decrease in contents of phosphorus, magnesium and potassium occurred. The content of microelements and non-nutrient elements did not change.     

二代野猪放牧对夹金山针阔混交林物种多样性与土壤理化性质的影响

为了深入认识二代野猪放牧对夹金山针阔混交林物种多样性特征和土壤理化性质的影响,以便为该区域针阔混交林的生态稳定性维持以及科学放牧提供参考,该研究在全面踏查的基础上,根据牧道数量、面积、野猪行为特征及活动范围划分4种放牧干扰强度(由强到弱依次为I、II、III、IV),并设置无干扰状态作为对照(CK),探讨不同放牧干扰强度对物种多样性和土壤理化性质的影响以及二者之间的作用关系。主要结果:(1)共记录到维管植物172种,隶属于55科117属,轻度干扰(IV)下乔灌草的科、属、种数目均达到最高。(2)乔灌草3层多样性指数对干扰强度的响应基本一致,IV级干扰下丰富度指数(S)、Shannon多样性指数(H′)和Simpson优势度指数(D)达到最大,高于CK,随干扰增强多样性水平均趋下降;各干扰强度间Pielou均匀度指数(E)差异不显著。(3)相比于CK,野猪放牧致使土壤含水量、最大含水量、全氮含量下降,放牧压力越大,下降比例越大;土壤孔隙度、全磷、速效磷、有机质含量在IV级干扰时有所增加, I–III级干扰下明显削减;土壤密度随干扰增强而增大。(4)冗余分析结果表明:土壤有机质含量、速效磷...     

Influence of management on the species composition of epiphytic cryptogams in Danish Fagus forests

Abstract. The purpose of this study is to evaluate and to quantify the influence of management on the epiphytic species composition in Danish Fagus sylvatica forests. Trunks were chosen at random within selected blocks in both managed and unmanaged Fagus stands.117 trunks in 43 sample plots in three forests were investigated. Cover was estimated for 72 lichens, 29 bryophytes and two fungi on vertical trunks 0.3 ‐2 m above ground. 18 explanatory variables were recorded and arranged in three groups: eight management‐related variables, six micro‐climatic‐ and soil variables, and four geographical‐ and geological variables. Canonical Correspondence Analysis was used to test and to quantify the explaining power of the three groups of variables applying the variation partitioning approach. Detrended Correspondence Analysis was used to evaluate whether important gradients were ignored. It was concluded that the traditional ‘shelterwood uniform system’ used in Fagus forests has a marked influence on the epiphytic species composition. Thus, management‐related variables explained more than one third of the total variation explained, which equals 10.9% of the total variation. Microclimatic and soil variables explained 9.0%, and geographical and geological variables explained 6.0%. The following three recommendations are suggested to reduce the significant influence of management on the epiphytic species composition. First, it should be attempted to ensure a continuous occurrence of some big trees per ha to be left for natural death and decomposition. Second, regular thinning is necessary, especially in the first part of rotation. Third, a multi‐layered forest, where wind and desiccation effects are minimized, is recommended.     

The effects of climate change on the birch pollen season in Denmark

During the last two decades the climate inDenmark has become warmer and in climatescenarios (IPCC, 2001) it is foreseen that thetemperature will increase in the comingdecades. This predicted future increase intemperature will probably affect both theflowering of plants and the dispersion ofpollen in the air. In this study the alreadyobserved effects on the birch pollen season arestudied.Trend analyses of the birch pollen seasonfor two stations in Denmark more than 200 kmapart give similar results. In Copenhagen thereis a marked shift to an earlier season – itstarts about 14 days earlier in year 2000 thanin 1977, the peak-date is 17 days earlier andthe season-end is 9 days earlier. For Viborgthe trend to an earlier season is in generalthe same, but slightly smaller.During the same period there has also beena distinct rise in the annual-total amount ofbirch pollen, peak-values and days withconcentrations above zero.Rising mean temperatures during winter andspring can explain the calculated trends towardearlier pollen season. Models for estimation ofthe starting date based on Growing Degree Hours(GDH's) give very fine results with acorrelation coefficient around 0.90 and rmserror around 4.2 days.For annual-total there is a significantpositive correlation with the mean temperaturein the growing season the previous year.     

Aluminum effects on the kinetics of calcium uptake into cells of the wheat root apex

The effects of aluminum on the concentration-dependent kinetics of Ca²⁺ uptake were studied in two winter wheat (Triticum aestivum L.) cultivars, Al-tolerant Atlas 66 and Al-sensitive Scout 66. Seedlings were grown in 100 M CaCl₂ solution (pH 4.5) for 3 d. Subsequently, net Ca²⁺ fluxes in intact roots were measured using a highly sensitive technique, employing a vibrating Ca²⁺-selective microelectrode. The kinetics of Ca²⁺ uptake into cells of the root apex, for external Ca²⁺ concentrations from 20 to 300 M, were found to be quite similar for both cultivars in the absence of external Al; Ca²⁺ transport could be described by Michaelis-Menten kinetics. When roots were exposed to solutions containing levels of Al that were toxic to Al-sensitive Scout 66 but not to Atlas 66 (5 to 20 M total Al), a strong correlation was observed between Al toxicity and Al-induced inhibition of Ca²⁺ absorption by root apices. For Scout 66, exposure to Al immediately and dramatically inhibited Ca²⁺ uptake over the entire Ca²⁺ concentration range used for these experiments. Kinetic analyses of the Al-Ca interactions in Scout 66 roots were consistent with competitive inhibition of Ca²⁺ uptake by Al. For example, exposure of Scout 66 roots to increasing Al levels (from 0 to 10 M) caused the K _m for Ca²⁺ uptake to increase with each rise in Al concentration, from approx. 100 M in the absence of Al to approx. 300 M in the presence of 10 M Al, while having no effect on the V _max. The same Al exposures had little effect on the kinetics of Ca²⁺ uptake into roots of Atlas 66. The results of this study indicate that Al disruption of Ca²⁺ transport at the root apex may play an important role in the mechanisms of Al toxicity in Al-sensitive wheat cultivars, and that differential Al tolerance may be associated with the ability of Ca²⁺-transport systems in cells of the root apex to resist disruption by potentially toxic levels of Al in the soil solution.We would like to thank Dr. Lionel F. Jaffe, Director of the National Vibrating Probe Facility, Marine Biological Laboratory, Woods Hole, Mass., USA, for making his calcium-selective vibrating-mi-croelectrode system available for a portion of this work. The research presented here was supported in part by USDA/NRI Competitive Grant number 91-37100-6630 to Leon Kochian. Contribution from the USDA-ARS, U.S. Plant, Soil and Nutrition Laboratory, Cornell University, Ithaca, N.Y. This research was part of the program of the Center for Root-Soil Research, Cornell University, Ithaca, N.Y. Department of Soil, Crop and Atmosphere Science, paper No. 1741.     

Evaluation of the effects of the parameters involved in the purification of clavulanic acid from fermentation broth by aqueous two-phase systems

The purification of clavulanic acid (CA), which is an important β-lactam antibiotic produced by submerged cultivation of Streptomyces clavuligerus, was studied through the use of phosphate and polyethylene glycol-based aqueous two-phase systems. The parameters’ effect on the yield and purification was evaluated through an experimental design and the preliminary results showed that the polyethylene molecular mass and tie-line length and phase volume ratio exerted the strongest effect on the yield and distribution coefficient in the range tested. In addition, the response surface methodology was used to optimize the distribution coefficient, yield, and purification factor. The optimal conditions of yield and purification factor are in the regions where polyethylene has a low molecular mass, pH close to the isoelectric point, and lower top phase volume. A 100% yield and a 1.5-fold purification factor are obtained when extracting CA by maximizing the conditions of an aqueous two-phase system.     

泛素化修饰对维甲酸诱导基因I样受体家族(RLRs)信号通路分子调控作用的研究进展

维甲酸诱导基因I样受体家族(retinoid acid-inducible gene-I-like receptors, RLRs)信号通路作为众多抗感染免疫信号通路之一，在诱导促炎细胞因子、趋化因子和I型干扰素产生等方面发挥重要的调控作用。作为蛋白质翻译后修饰之一的泛素化(ubiquitination)，是由泛素蛋白(ubiquitin)与目标蛋白上不同的氨基酸位点产生结合来调控蛋白的命运，如启动蛋白酶体途径降解蛋白或激活转运等功能。而RLRs信号通路分子的泛素化修饰既是调控多种效应因子的方式之一，也是病毒经此诱发动物重要疾病以及自身免疫病、慢性炎症的经典路径之一。本文主要综述RLRs信号通路中重要的效应器分子的典型结构特征、泛素化修饰类型和功能，探讨泛素化修饰调控RLRs信号通路关键分子的作用，为相关疾病的干预或治疗提供参考。