The Effects of Temperature on Pratylenchus scribneri and P. alleni Populations on Soybeans and Tomatoes

In soil temperature tests, rates of Pratylenchus scribneri and P. alleni reproduction were measured at various lemperatures on ''Clark 63'' and ''Cutler 71'' soybeans and ''Rutgers'' tomatoes. Recovered P. scribneri equaled or exceeded initial inoculum levels at temperatures of 27.5 C or higher on soybeans, and at 20 C or higher on tomatoes. Population increases were greatest at 3.5 C on both hosts. Populations increased on soybeans, but not on tomatoes, when soil temperature was raised from 25 to 35 C for either 3 or 9 days. Recovered P. alleni were less than the initial inoculum at 27.5 C but higher at 32 and 37.5 C and at 27.5 C on tomatoes, the lowest temperature tested for this nematode. In the field, soil temperatures 10 cm deep in eastern Kansas soybean growing areas reach 27.5 C only occasionally and for relatively short periods, which probably explains the relatively low and variable populations of P. scribneri and P. alleni on soybeans there.     

Marigold,Castor Bean,and Chrysanthemum as Controls of Meloidogyne incognita and Pratylenchus alleni

Root and soil populations of Meloidogyne incognita were significantly fewer from marigold, castor bean, and chrysanthemum than from tomato roots and soil, but not from fallow soil. Root populations of Pratvlenchus alleni were significantly fewer from marigold, castor bean, and chrysanthemum than from tomato: marigold had the fewest. Root populations of M. incognita and P. alleni from tomato simultaneously cultivated with marigold, castor bean, and chrysanthemum were significantly fewer than from tomato cultivated alone. Aborted giant cells and dead M. incognita (larvae and females) were observed in roots of marigold and castor bean, but not in chrysanthemum or tomato. Significantly more males than females occurred in castor bean roots. lnfcction sites of P. alleni appeared normal in all hosts. Thin-layer and column chromatography of alcoholic extracts from castor bean revealed no nematicidal thiophenc derivatives.     

Effect of wet and dry cycles in calcareous soil on mineral nutrient uptake of two grasses,Agrostis stolonifera L. and Festuca ovina L.

Shoot uptake of mineral nutrients (Ca, Cu, Fe, K, mg, Mn, P, S, Zn) by Agrostis stolonifera L. was compared with Festuca ovina L. under wet and dry cycles. Such conditions are typical for A. stolonifera sites, whereas F. ovina is growing mostly on consistently drier and better-drained soils. Plants were grown in a glasshouse, at controlled temperature and light conditions, using two moisture regimes, one constant at 60% WHC (water holding capacity), one wet/dry fluctuating between 35 and 100% WHC. Above ground and total biomass production was lower under wet/dry treatment than at constant water regime in F. ovina, but did not differ between regimes in A. stolonifera. Shoot uptake of most elements was severely reduced in F. ovina at the wet/dry regime. Shoot uptake and concentrations of most elements studied (Cu, K, Mn, P, S, Zn) were lower (p<0.05) under wet/dry treatment than at constant regime in A. stolonifera and tended to be lower also of Fe and Mg. Differences in biomass production observed are consistent with field evidence that A. stolonifera grows in sites which are periodically flooded but may become quite dry during other periods, and that F. ovina is limited to sites which are consistently drier and better drained. Evidence from the present study, however, does not support any view that alternating wet and dry cycles, as typical of A. stolonifera field sites, would be beneficial to nutrient acquisition of this species but that biomass production may develop normally at the lower uptake of most mineral nutrients measured under the wet/dry regime. Such regimes are decidedly unfavourable to both growth and nutrient acquisition of F. ovina.     

Tuber surface microorganisms influence the susceptibility of potato tubers to late blight

Potato tubers (cvs Cara and Bintje) were grown in compost in a glasshouse and immature tubers harvested 57, 68 and 78 days after planting. Two moisture levels were imposed after the first harvest by disconnecting the water supply to one of the treatments and allowing the soil in that treatment to dry naturally. Tubers from wetter compost (59.4% moisture holding capacity) were more resistant to Phytophthora infestans than those from drier compost (14.7% moisture holding capacity) 78 days after planting. The potential causes of this difference were investigated. Aqueous extracts of wet compost did not inhibit the growth of P. infestans. The susceptibility of the internal tuber tissue, from which the periderm had been removed, was different to whole tuber susceptibility. The internal tissue of tubers from wet compost was more susceptible (cv. Cara), or as susceptible (cv. Bintje) as that of tubers from dry compost 78 days after planting. Fungi were isolated from the surface of whole tubers and there were no differences between the populations of potentially antagonistic fungal genera on tubers from wet and dry compost. As the experiment progressed, the number of bacteria per gram fresh weight on tubers grown in wet compost increased, whereas that on tubers from drier compost decreased (cv. Bintje) or remained similar (cv. Cara). There were significantly (P= 0.008) more bacteria on the surface of tubers from wet compost 78 days after planting. When P. infestans was co-cultured in Petri dishes with randomly selected tuber surface bacteria, some isolates (≤ 16.7%) inhibited the growth of the fungus. The percentage of the total bacterial population that was antagonistic to P. infestans was not significantly affected by soil moisture level (P= 0.368). The greater numbers of bacteria, of which a proportion are antagonistic to P. infestans, on the surface of tubers grown in wet compost may account for the greater resistance to tuber blight in that instance.     

Quantifying the effect of soil moisture content on segmenting root system architecture in X-ray computed tomography images

Aims

A commonly accepted challenge when visualising plant roots in X-ray micro Computed Tomography (μCT) images is the similar X-ray attenuation of plant roots and soil phases. Soil moisture content remains a recognised, yet currently uncharacterised source of segmentation error. This work sought to quantify the effect of soil moisture content on the ability to segment roots from soil in μCT images.

Methods

Rice (Oryza sativa) plants grown in contrasting soils (loamy sand and clay loam) were μCT scanned daily for nine days whilst drying from saturation. Root volumes were segmented from μCT images and compared with volumes derived by root washing.

Results

At saturation the overlapping attenuation values of root material, water-filled soil pores and soil organic matter significantly hindered segmentation. However, in dry soil (ca. six days of drying post-saturation) the air-filled pores increased image noise adjacent to roots and impeded accurate visualisation of root material. The root volume was most accurately segmented at field capacity.

Conclusions

Root volumes can be accurately segmented from μCT images of undisturbed soil without compromising the growth requirements of the plant providing soil moisture content is kept at field capacity. We propose all future studies in this area should consider the error associated with scanning at different soil moisture contents.     

Vertical Distribution of the Free-Living Amoeba Population in Soil under Desert Shrubs in the Negev Desert, Israel

A field study was designed to examine the effect of desert shrubs on the dynamics of free-living amoebae in arid soil. Soil samples from 0- to 50-cm depths were collected at 10-cm intervals in each of the four seasons. The vertical distributions of the four main morphological types of amoebae, grouped according to their mobility, and of small flagellate populations were measured under the canopies of Hammada scoparia and Atriplex halimus, shrubs belonging to the chloride-absorbing xerohalophytes. The result obtained from the field study demonstrated that the total number of protozoa was significantly higher during the wet seasons (winter and spring) than during the dry seasons. The protozoan population was more diverse under the canopy of H. scoparia during the wet seasons, reaching 8,000 individuals per 1 g of dry soil, whereas during the dry seasons, the populations were higher under the canopy of A. halimus, with a mean of 250 individuals. The protozoan population in the deeper layers (40 to 50 cm) was found to be as active as that in the upper layers, demonstrating that, in the desert, soil columns below 20 cm are fertile and worth studying. The type 1 amoebae (e.g., Acanthamoeba and Filamoeba spp.) were the most abundant throughout the study period, and their numbers were significantly higher than those of the other amoeba types.     

Photosynthate Partitioning and Enzymes of Sucrose Metabolism in Sugarbeet Roots

Populations of sugarbeet (Beta vulgaris L.) plants that differed in taproot/leaf weight ratio and in photosynthate partitioning between taproots and fibrous roots did not differ in root/shoot ratio as indicated by relative dry weight distribution. Based on the hypothesis that dry weight distribution is influenced by the metabolism of imported sucrose, we examined the relationships between the activity of the enzymes of sucrose metabolism and dry weight distribution as a function of genotype and ontogeny. A decreased specific activity of acid invertase in taproots was associated with increased taproot/fibrous root weight ratio at 21 and at 28 days post-emergence. Alkaline invertase activity was negatively correlated with taproot/fibrous root weight ratio at 28 days. Sucrose synthetase specific activities of taproots were not correlated with dry matter distribution. Acid invertase may influence photosynthate partitioning between the taproot and fibrous roots via regulation of sucrose levels in the region of fibrous root initiation.     

Soil pH Effects on Nematode Populations Associated with Soybeans

''Amsoy'' soybeans were grown for 2 months in nonsterilized Jackson silt loam amended to pH 4.0, 6.0, and 8.0. Nematodes were extracted biweekly from soil and roots. The greatest numbers of Pratylenchus alleni colonized soybean roots at pH 6.0. Hoplolaimus galeatus and members of the Tylenchinae-Psilenchinae survived best at pH 6.0, while numbers o f the Dorylaimoidea were greatest at both pH 6.0 and 8.0. The non-stylet nematodes were recovered in greater numbers from pH 8.0 soil. Potassium, manganese, and phenols were highest in soybean plants grown in pH 4.0 soil, the pH at which there were the fewest nematodes. A thicker suberized outer layer o f root tissue occurred in plants grown at pH 4.0.     

Importance of internal hydraulic redistribution for prolonging the lifespan of roots in dry soil

Redistribution of water within plants could mitigate drought stress of roots in zones of low soil moisture. Plant internal redistribution of water from regions of high soil moisture to roots in dry soil occurs during periods of low evaporative demand. Using minirhizotrons, we observed similar lifespans of roots in wet and dry soil for the grapevine 'Merlot' (Vitis vinifera) on the rootstock 101-14 Millardet de Gramanet (Vitis riparia x Vitis rupestris) in a Napa County, California vineyard. We hypothesized that hydraulic redistribution would prevent an appreciable reduction in root water potential and would contribute to prolonged root survivorship in dry soil zones. In a greenhouse study that tested this hypothesis, grapevine root systems were divided using split pots and were grown for 6 months. With thermocouple psychrometers, we measured water potentials of roots of the same plant in both wet and dry soil under three treatments: control (C), 24 h light + supplemental water (LW) and 24 h light only (L). Similar to the field results, roots in the dry side of split pots had similar survivorship as roots in the wet side of the split pots (P = 0.136) in the C treatment. In contrast, reduced root survivorship was directly associated with plants in which hydraulic redistribution was experimentally reduced by 24 h light. Dry-side roots of plants in the LW treatment lived half as long as the roots in the wet soil despite being provided with supplemental water (P < 0.0004). Additionally, pre-dawn water potentials of roots in dry soil under 24 h of illumination (L and LW) exhibited values nearly twice as negative as those of C plants (P = 0.034). Estimates of root membrane integrity using electrolyte leakage were consistent with patterns of root survivorship. Plants in which nocturnal hydraulic redistribution was reduced exhibited more than twice the amount of electrolyte leakage in dry roots compared to those in wet soil of the same plant. Our study demonstrates that besides a number of ecological advantages to protecting tissues against desiccation, internal hydraulic redistribution of water is a mechanism consistent with extended root survivorship in dry soils.     

Deuterium labelling of roots provides evidence of deep water access and hydraulic lift by Pinus nigra in a Mediterranean forest of NE Spain

We studied the tree access to deep water sources and the possibility of hydraulic lift from the deep roots of a Pinus nigra tree to the shallow soil layers in a Mediterranean forest of NE Spain. We also studied the use of hydraulically lifted water by neighboring trees, shrubs, and sprouts. We enriched the roots of a large P. nigra (10 m tall) with deuterium by accessing them from a below ground cave. During the next 3 days we measured stable deuterium isotopic composition of xylem sap, shoot predawn and midday water potentials, and the leaf δ¹³C and δ¹⁵N of the P. nigra tree, neighboring Quercus ilex ballota trees and sprouts, and Juniperus oxycedrus shrubs. The study was conducted both in dry summer and in wet spring. In summer, deuterated water absorbed by deep roots of P. nigra appeared in the stem water of neighboring plants and in surface soil. The most δD-enriched plant xylem sap was found in the enriched P. nigra tree, followed by the Q. ilex sprouts, the small Q. ilex trees and the surface soil (15 cm). All these trends disappeared in the wet spring season, when HDO only slightly appeared in the surface soil. The results show that the studied P. nigra tree accesses deep water source and conducts hydraulic lift in this Mediterranean forest in dry summer but not necessarily in wet spring.     

Prevalence of endoparasitic mites on four West African leaf‐litter frogs depends on habitat humidity

Amphibian species are known to carry endoparasitic mites. The infestation probability, prevalence, and intensity of mites vary among species and habitats. Mites of the genus Endotrombicula are known to infest African and Malagasy frogs. However, the factors leading to an increase in the probability of mite infestation are unknown. To test for inter‐ and intraspecific differences in infestation probability and its potential correlation with sex, age, habitat preferences, and/or season within a species‐rich West African leaf‐litter frog assemblage, we examined more than 6,800 individual frogs for the presence of mites throughout two independent time increments, 1999–2000 and 2016–2017. We found only members of the leaf‐litter frog genus Phyrnobatrachus to be infested, while other syntopically occurring genera were not affected. Within Phrynobatrachus, only four out of eight species were infested. Mites prevalence differed between species (highest P. phyllophilus, followed by P. alleni), sex (males higher than females in P. alleni and P. phyllophilus), and age (adults higher than juveniles in P. alleni), as well as season (more mites during wet than dry season in P. phyllophilus). The prevalence of mite infestation did not influence mate choice in P. alleni. Increased humidity showed a clear positive effect on infestation prevalence. We also detected a marked decrease in the prevalence of mites from 1999–2000 to 2016–2017, a period during which climatological changes within the study area have been reported with a tendency toward drier conditions. The decrease in mite infestation prevalence over time might be a signal of increasingly drier conditions.     

Anhydrobiosis in Pratylenchus penetrans and Tylenchorhynchus n. sp. in Cultivated Soils Cropped to Winter Rye

Anhydrobiotes of Pratylenchus penetrans were found in two cultivated soils sown to rye in southern Ontario during the growing season. Anhydrobiotes at the 0-2.5-cm depth were recovered from 9 and 6 of 11 samplings, respectively, of a Vineland silt loam and a Fox loamy sand during the dry summer of 1983. At the 2.5-15.0-cm depth, anhydrobiotes were recovered less frequently. In the summer of 1984, anhydrobiotes of P. penetrans were recovered once and anhydrobiotes of Tylenchorhynchus n. sp. twice in 11 samplings. The percentages of P. penetrans populations that were anhydrobiotes in 1983 and 1984 were closely related to soil moisture content and corresponding moisture tensions. Populations of P. penetrans were greatest in October in the lower soil depth, 2.5-15.0 cm; those of Tylenchorhynchus n. sp. were greater in the surface layer of soil, 0-2.5 cm, and peaked in August.     

Shifts in root-associated fungal communities under drought conditions in Ricinus communis

Rhizosphere and endophytic microbial communities are crucial for plant fitness and affect how plants cope with abiotic stress. In this study, we provide evidence that drought stress affected alpha and beta diversity of fungal communities associated with the roots and rhizosphere of castor bean (Ricinus communis) through metabarcoding of 18S rRNA gene. Plants were cultivated in soil columns in the greenhouse at three different watering regimes, i.e., 50% water holding capacity (WHC; wet) or adjusted to 50% WHC every 2 weeks (dry) or every month (extremely dry). Ascomycota, Basidiomycota, Chytridiomycota and Fusarium dominated the soil and rhizosphere and Fusarium, Cladosporium, Mucor, Cystofilobasidium, Penicillium and Malassezia the roots. Under extremely dry conditions, root and rhizosphere taxonomic and functional alpha diversity increased compared to the wet treatment. However, the species turnover decreased in the stressed compared to the non-stressed roots, enriching specific fungal groups. Drought did not affect the association between castor bean and arbuscular mycorrhizal (AM) fungi. The phenolic content in stressed roots was significantly lower compared to wet conditions with a negative correlation between AM fungal colonization and root phenolic content.     

Biosynthesis, translocation, and accumulation of betaine in sugar beet and its progenitors in relation to salinity

Like other halophytic chenopods, sugar beet (Beta vulgaris L.) can accumulate high betaine levels in shoots and roots. N,N,N-trimethylglycine impedes sucrose crystallization and so lowers beet quality. The objective of this research was to examine the genetic variability and physiological significance of betaine accumulation in sugar beet and its relatives. Three cultivated genotypes of B. vulgaris and two genotypes of the wild progenitor B. maritima L. were grown with and without gradual salinization (final NaCl concentration = 150 millimolar). At 6 weeks old, all five genotypes had moderately high betaine levels in shoots and roots when unsalinized (averages for all genotypes: shoots = 108 micromoles per gram dry weight; roots = 99 micromoles per gram dry weight). Salinization raised betaine levels of shoots and roots 2- to 3-fold, but did not greatly depress shoot or root growth. The genotype WB-167—an annual B. maritima type—always had approximately 40% lower betaine levels in roots than the other four genotypes, although the betaine levels in the shoots were not atypically low.

The site and pathway of betaine synthesis were investigated in young, salinized sugar beet plants by: (a) supplying 1 micromole [¹⁴C]ethanolamine to young leaf blades or to the taproot sink of intact plants; (b) supplying tracer [¹⁴C]formate to discs of leaf, hypocotyl, and taproot tissues in darkness. Conversion of both ¹⁴C precursors to betaine was active only in leaf tissue. Very little ¹⁴C appeared in the phospholipid phosphatidylcholine before betaine was heavily labeled; this was in marked contrast to the labeling patterns in salinized barley. Phosphorylcholine was a prominent early ¹⁴C metabolite of both [¹⁴C]ethanolamine and [¹⁴C]formate in all tissues of sugar beet. Betaine translocation was examined in young plants of sugar beet and WB-167 by applying tracer [methyl-¹⁴C]betaine to a young expanded leaf and determining the distribution of ¹⁴C after 3 days. In all cases, extensive ¹⁴C translocation to young leaves and taproot sink occurred; neither in the fed leaf nor in sink organs were any ¹⁴C metabolites of betaine detected.

     

Species of Pratylenchus Associated with Solanum tuberosum cv Superior in Ohio

Seventy-three Ohio fields comprising ca. 440 ha of cv Superior potatoes were surveyed in 1977 for plant-parasitic nematodes. Of eight genera of plant-parasitic nematodes, Pratylenchus was found most frequently, occurring in 65% of the soil samples and 84% of the root samples. Populations of Pratylenchus were consistently higher than populations of the other nematode genera. The six species of Pratylenchus extracted from potato roots, in descending order of frequency, were P. crenatus, P. penetrans, P. scribneri, P. alleni, P. thornei, and P. neglectus. Prevalence of these Pratylenchus species in Ohio potato fields suggests that they could be involved with vascular wilt fungi in premature death of cv Superior potato vines known in Ohio as "early dying."     

Influence of Some Environmental Factors on Populations of Pratylenchus minyus in Wheat

The distribution and density of Pratylenchus minyus and possible relationships of several environmental components, including ammonium nitrate, were investigated in a wheat field in South Australia. Seasonal variation as measured every 2-4 weeks was eliminated from the observations by periodic regression. Correlation and regression analyses were then used to investigate the association of host plant, rainfall, temperature, and the fungus Gaeumannomyces graminis with P. minyus. Other than seasonal effects, soil moisture and G. graminis were the only components associated with P. minyus. Ammonium nitrate usually was correlated with fewer P. minyus in wheat roots. Much higher numbers of P. minyus were observed in seminal than in crown roots of wheat.     

Symptomatology and Histopathology of Soybean Roots Infected by Pratylenchus scribneri and P. alleni

Size of lesions caused by Pratylenchus scribneri on roots of ''Clark 63'' soybean was correlated with nematode colony size within roots. A single nematode was capable of causing a detectable lesion. When a root became highly necrotic and shrunken, few nematodes but numerous eggs remained in the tissue. In histological sections made 5, 11, 18, and 45 d after planting, P. scribneri was located entirely within the cortex and generally was oriented longitudinally to the vascular cylinder, either outstretched in the same plane or coiled through several cells. Nematodes moved intracellularly, causing extensive rupturing of cell walls, retraction and disappearance of cytoplasm, and thickening of cell walls and necrosis of cells around feeding sites. Depth of penetration within the cortex and necrosis of cells increased with time after infection, eventually resulting in formation of cavities in the cortex and occasional secondary injury to the endodermis. Stele tissue was unaffected by feeding, and damage to the epidermis was limited to nematode entry points. Orientation of P. alleni and histopathology of its infection at 45 days were identical to those of P. scribneri, except that there was no injury to the endodermis.     

Efficacy of Metarhizium anisopliae isolate MAX-2 from Shangri-la, China under desiccation stress

Background

Metarhizium anisopliae, a soil-borne entomopathogen found worldwide, is an interesting fungus for biological control. However, its efficacy in the fields is significantly affected by environmental conditions, particularly moisture. To overcome the weakness of Metarhizium and determine its isolates with antistress capacity, the efficacies of four M. anisopliae isolates, which were collected from arid regions of Yunnan Province in China during the dry season, were determined at different moisture levels, and the efficacy of the isolate MAX-2 from Shangri-la under desiccation stress was evaluated at low moisture level.

Results

M. anisopliae isolates MAX-2, MAC-6, MAL-1, and MAQ-28 showed gradient descent efficacies against sterile Tenebrio molitor larvae, and gradient descent capacities against desiccation with the decrease in moisture levels. The efficacy of MAX-2 showed no significant differences at 35% moisture level than those of the other isolates. However, significant differences were found at 8% to 30% moisture levels. The efficacies of all isolates decreased with the decrease in moisture levels. MAX-2 was relatively less affected by desiccation stress. Its efficacy was almost unaffected by the decrease at moisture levels > 25%, but slowly decreased at moisture levels < 25%. By contrast, the efficacies of other isolates rapidly decreased with the decrease in moisture levels. MAX-2 caused different infection characteristics on T. molitor larvae under desiccation stress and in wet microhabitat. Local black patches were found on the cuticles of the insects, and the cadavers dried without fungal growth under desiccation stress. However, dark black internodes and fungal growth were found after death of the insects in the wet microhabitat.

Conclusions

MAX-2 showed significantly higher efficacy and superior antistress capacity than the other isolates under desiccation stress. The infection of sterile T. molitor larvae at low moisture level constituted a valid laboratory bioassay system in evaluating M. anisopliae efficacy under desiccation stress.     

EFFECTS OF SOIL WATER DISTRIBUTION ON THE LATERAL ROOT DEVELOPMENT OF THREE SPECIES OF CALIFORNIA OAKS

The responses of seedling root systems of three species of oaks in California to two experimental soil moisture regimes were studied by comparing lateral root development, root and shoot weights, and root: shoot ratios. In the first soil moisture treatment the taproot was allowed to extend into moist soil throughout the duration of the experiment (control), while in the second treatment (shallow) the taproot grew into a dry substrate below 30 cm of moist soil. The treatments were intended to approximate soil moisture conditions experienced by oak seedlings in the field when deep soil water sources vary in their accessibility (control: accessible, shallow: inaccessible). Lateral root growth of Quercus agrifolia did not increase significantly when the primary root tip died in the shallow treatment, resulting in an overall decrease in the percent of the root system composed of lateral roots. Q. douglasii and Q. lobata increased lateral root weights by 80% and 70%, respectively, on the upper 30 cm of the primary root when the primary root tip died. Q. lobata was the only species that decreased in shoot and root weight (25% and 21%, respectively) with the loss of the root tip, indicating that, unlike the other species, it was dependent on the primary root for maximum growth. The morphological responses of these species correspond with their distributions and also may be a factor that influences their interactions with other species.     

川滇高山栎灌丛萌生过程中的营养元素供应动态

萌生更新是森林更新的重要方式, 是硬叶栎林受到干扰后植被恢复的主要机制。以位于青藏高原东南缘的川西折多山东坡川滇高山栎(Quercus aquifoliodes)灌丛为研究对象, 调查分析了砍伐后灌丛萌生过程中基株根系和萌株生物量动态、营养元素含量, 以及基株根系和土壤对萌株生长过程中的营养元素供应动态。结果表明, 川滇高山栎灌丛平均地上和地下生物量分别为(11.25 ± 0.92) t·hm^-2和(34.85 ± 2.02) t·hm^-2, 具有较大的根冠比(3.10:1); 萌生过程中, 萌株生物量呈线性增加趋势, 以灌丛活细根生物量变化为最大, 其次是活中根和活粗根, 树桩和根蔸生物量变化最小; 萌生过程中, 灌丛细根和中根N、P含量表现为先增加、后降低的变化趋势, 萌生初期树桩、粗根和根蔸中N和K的含量明显下降, 根蔸中Ca含量略有下降, 而P没有明显下降, 根系Mg含量变化幅度较大, 灌丛地下根系储存了较多的营养元素; 土壤、树桩、粗根和根蔸是川滇高山栎灌丛砍伐后0-120天萌生生长的主要营养来源, 砍伐后60天, 萌株生长所需的营养除K元素主要来源于根系外, 其余营养元素主要来源于土壤; 在砍伐后60-120天, 基株根系对萌株生长所需的N、K和Ca贡献较大, 而对P和Mg的贡献较小; 在砍伐后120-180天, 根系除K元素对萌生生长还保持较大的贡献外, 对其余营养元素的贡献均较小。高山栎林管理要注重加强地下根系的保护。