Spiraea Salicifolia Research Articles

До питання збільшення довговічності деяких видів кущових рослин

Наведено результати багаторічних досліджень проблеми підвищення віку, лісівничих і декоративних якостей восьми видів кущів: спіреї середньої (Spiraea media Schmidt), с. Вангутта (S. vanhouttei (Brio) Zab.), с. верболистої (S. salicifolia L.), жимолості звичайної (Lonicera xуlosteum L.), ж. татарської (L. tatarica L.), бирючини звичайної (Ligustrum vulgare L.), свидини кров’яної (Cornus sanguinea L.) та с. білої (C. alba L.) у зелених насадженнях міста Біла Церква та у лісових культурах Томилівського лісництва ДП «Білоцерківське лісове господарство». Періодично проводили обрізування їх надземної частини. Встановлено, що обрізування крон з періодичністю 15-17 років сприяє збільшенню довговічності кущів досліджуваних видів на 33-35 років і більше. За відсутності таких заходів повне відмирання кущів відбувається у віці 19-20 років. Періодичне обрізування сприяє також підвищенню лісівничих та декоративних властивостей кущів.

Synanthropization of the Baltic-type raised bog “Roby” (NW Poland)

Abstract Raised and transitional peat bogs, despite their considerable resistance to synanthropization, as a result of anthropogenic transformations are exposed to the colonisation by alien species. One of them is the peatland “Roby”, where, in the years 2007-2009 and 2014, floristic, phytosociological and soil studies were carried out in order to record the signs of ongoing synanthropization. Conducted observations and analyses indicated that the expansion of willows has taken place and at present they occupy a large part of the bog, encroaching into bog birch forest and successfully competing with Myrica gale. Progressive peat mineralisation and constructed surfaced roads within the bog, contributed to the appearance and wide distribution of synanthropic species, such as: Urtica dioica, Impatiens parviflora and Spiraea salicifolia. Raised bog communities and their characteristic species occur on a few fragments of the bog, in north-western part, where water regime is shaped mainly by precipitation and peat deposit is fairly well-preserved. At the same time, in the patches of these communities, a distinct unfavourable increase in the share of Molinia caerulea is observed.

黄土丘陵沟壑区主要物种植冠种子库动态及其生态策略

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土丘陵沟壑区主要物种植冠种子库动态及其生态策略 DOI: 10.5846/stxb201305101011 作者: 作者单位: 西北农林科技大学资源环境学院,中国科学院水利部水土保持研究所,水利部海河水利委员会海河流域水土保持监测中心站,中国科学院水利部水土保持研究所,西北农林科技大学林学院,西北农林科技大学水土保持研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院重要方向项目(KZCX2-EW-406);国家自然科学基金重点项目(41030532). Dynamics and ecological strategies of aerial seed bank of main species in the hill-gully Loess Plateau Author: Affiliation: ollege of Resources and Environment, Northwest Agriculture and Forest University,Institute of Soil and Water Conservation, Chinese Academy of Sciences,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植冠种子库是植物适应环境并应对外界干扰的种子生态策略之一,研究了黄土丘陵沟壑区12种主要植物植冠种子库动态,结果表明:杠柳不具有植冠种子库,其他11种植物均具有植冠种子库;除了黄刺玫种子在翌年5月达到脱落高峰,其他植物大部分种子在冬季脱落,其中杠柳、达乌里胡枝子、茭蒿、黄柏刺和水栒子的大部分种子脱落集中偏早,铁杆蒿和土庄绣线菊的大部分种子脱落集中偏晚;植冠宿存对大部分植物种子的萌发特性表现为促进作用;但不同植物种子的萌发时滞对植冠宿存响应差异较大;9种植物种子在植冠上宿存至翌年2月底,其种子活力仍能维持达60%以上;该区植物表现出不同的植冠种子库策略,通过不同的方式来减少干扰的威胁,提高成功萌发与更新的几率,它们或具有较大规模的宿存量、或调控种子萌发特性、或提高种子维持活力的百分比。此外,全面了解该区植物形成植冠种子库的机理及对应的生态策略还有待于全面、深入的研究。 Abstract:Delayed seed dispersal, leading to form an aerial seed bank, is one way to deal with disturbances in the special environment. Previous studies on aerial seed bank have focused on the fire-prone and arid desert habitats. However, there are few studies on aerial seed storage in the eroded slope habits, where lack of available soil water due to low soil water holding capacity caused by water erosion and drought. The dynamics of aerial seed banks, the seed germination and viability characteristics of 12 main species were studied in the hill-gully Loess Plateau, then the aerial seed bank strategies were analyzed which adapt the disturbances in the study region. The results showed that the seeds of Periploca sepium can't form aerial seed bank with no seed stored on plants until the end of the next February. While the seeds of the Rose xanthina can form the persistent aerial seed bank with seeds stored on plants until the next October. The other 10 species excepted Periploca sepium and Rose xanthina also can form aerial seed bank, which density are not significant high with percentages of seeds stored on plants below 5% up to the next May. Most seeds of the other 11 species dispersed during the winter, except the seeds of the Rose xanthina dispersed intensively until the next May. The seeds of the Periploca sepium, Lespedeza davurica, Artemisia giraldii, Berberis virgetorum and Cotoneaster multiflorus dispersed intensively earlier among 12 species while the seeds of the Artemisia gmelinii and Spiraea salicifolia dispersed intensively later among 12 species. Delayed seed dispersal promoted the ability of seed germination for most species. The cumulative percentage of seed germination rate reached the peak in December for Artemisia giraldii, Artemisia gmelinii and Hippophae rhamnoides, and at the end of the next February for Sophora davidii, Potentilla chinensis, Syringa oblata, Spiraea salicifolia, and in the next May for Lespedeza davurica. However, delayed seed dispersal reduced the ability of seed germination for the Berberis virgetorum. The seeds stored on plants belonged to different species need different time for seeds beginning to germinate. The seeds of nine species can retain on plants until the end of the next February, of which the percentage of seed with viability reached up to 60%. The percentages of the seeds with viability from five species were increased after stored on plants until the end of the next February. There were different aerial seed bank strategies for the species to deal with disturbances in the study region. The seeds avoided threaten from uncertainties of the erosion environments, then germinated and regenerated successfully by storing more seeds on the canopy, regulating the seed germination and increasing the percentage of viable seeds. Moreover, it's uncertain that weather the seeds can form aerial seed bank in different environments or in different years. The aerial seed bank types of some species varied as the environmental condition changed, which indicated that the aerial seed bank dynamics of some species had variability. Thus, more studies should be done in this field. 参考文献 相似文献 引证文献

四种园林植物对土壤镉污染耐受性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 四种园林植物对土壤镉污染的耐受性 DOI: 10.5846/stxb201306101560 作者: 作者单位: 浙江农林大学风景园林与建筑学院,浙江省森林生态系统碳循环与固碳减排重点实验室,浙江省森林生态系统碳循环与固碳减排重点实验室,浙江省森林生态系统碳循环与固碳减排重点实验室,浙江省森林生态系统碳循环与固碳减排重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31300581);国家"十二五"科技支撑项目(2012BAD22B0503);浙江省重大科技专项重点项目(2012C12909-5) Tolerance and accumulation of four ornamental species seedlings to soil cadmium contamination Author: Affiliation: College of Landscape and Architecture,Zhejiang A F University,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration,Zhejiang A F University,Lin’an,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration,Zhejiang A F University,Lin’an,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration,Zhejiang A F University,Lin’an,Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration,Zhejiang A F University,Lin’an Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用模拟Cd污染土壤培养法,测定了Cd胁迫下山矾、桑树、绣线菊、山茶4种园林植物幼苗的生长、生物量变化,根茎叶的Cd含量,光合色素含量与MDA含量,对耐性指数(Ti)、转移系数(TF)、生物富集系数(BCF)进行了评价。结果表明:(1)山矾、桑树、绣线菊和山茶的平均耐性指数分别为93.99、82.33、82.10和87.25;(2)4个树种幼苗根茎叶的Cd含量都随着Cd处理浓度的增加而增加,转移系数值(TF)都小于1,转移能力为山矾 > 山茶 > 绣线菊 > 桑树。对Cd累积能力为山矾 > 山茶 > 桑树 > 绣线菊;山矾和山茶生物量吸收的Cd总量显著高于绣线菊和桑树。(3)Cd处理浓度的不断增加, 叶绿素a/叶绿素b比值与对照相比变化不显著,类胡萝卜素的含量持续增加;桑树、山茶、山矾和绣线菊MDA含量分别平均上升为15%、10.17%、9.69%、12.86%。不同Cd浓度下,MDA上升幅度顺序为桑树 > 绣线菊 > 山茶 > 山矾。研究表明山矾具有很高的Cd耐性、转移能力、以及地上部分积累镉的能力,是一种抗Cd污染较好的园林绿化树种。 Abstract:Four kinds of ornamental plants, Symplocos caudate, Morus alba, Spiraea salicifolia, and Camellia japonica were tested under five cadmium (Cd) application rate levels that range from 0mg/kgto 100mg/kg in a greenhouse pot experiment. Effects of Cd stress on growth indexes, biomass increment, Cd content of root, stem, leaf, content of photosynthetic pigment, and content of MDA in them were investigated after one year growth. Tolerance index (Ti), Translocation factor(TF)and bio concentration factor(BCF)of 4 species are evaluated. The results showed that (1) Cd had distinct inhibition on the growth of plant, the average tolerance index of S. caudate, M. alba, S. salicifolia, and C. japonica were 93.99, 82.33, 82.10 and 87.25 separately. (2) With increasing soil Cd content, the 4 species seedlings had a increase of Cd content of root, stem and leaf. The Translocation factor of these tree species to soil Cd contamination are all lower than 1and followed the order of S.caudate > C. japonica > S. salicifolia > M. alba. BCF values of these tree species to soil Cd contamination followed the order of S. caudate > C. japonica > M. alba >S. salicifolia;The total contents of Cd absorbed in S. caudate and C. japonica are significantly higer than in S. salicifolia and M. alba. (3) Chlorophyll a/b values of them were not obviously changed compared with CK, but the contents of carotenoid of them increased with the increasing Cd concentration. The average content of MDA in M. alba, S. salicifolia, C. japonica and S. caudate increased 15%, 10.17%, 9.69% and 12.86% separately and followed the order of M. alba > S. salicifolia > C. japonica > S. caudate. The study suggested that S. caudate is a good candidate species for phytoremediation of Cd contaminated soil because of its higher Cd tolerance, transfer and accumulation ability of aboveground biomass. 参考文献 相似文献 引证文献

Morphological traits and physiological characteristics in drought tolerance in 20 shrub species on the Qinghai-Xizang Plateau

Aims Providing indispensably theoretical evidence for establishing indices of evaluation on drought tolerance in shrubs, and screening for tree species that are drought tolerant for afforestation in arid regions or for matching their characteristics with suitable habitat conditions are the key to vegetation restoration in the Qinghai-Xizang Plateau. However, these issues are not adequately addressed in recent research due to lack of systematic methods. Therefore, our objective was to make a comprehensive evaluation on drought tolerance in 20 shrub species collected from different areas in Qinghai-Xizang Plateau, and to study their underlying mechanisms in drought tolerance. Methods We made measurements on variables depicting root characteristics, including the root length(TRL), surface area(TRSA), volume(TRV), and tips number(TRTN) of all roots, the root length(FRL), surface area(FRSA), volume(FRV), and tips number(FRTN) of fine roots(d ≤2 mm), and derived plant characteristic indices including thickness of cuticle(CT), thickness of palisade tissue(TPT), thickness of spongy tissue(TST), TPT/TST, thickness of leaf(LT), palisable tissue cell density, and tissue structural tense ratio(CTR = TPT/LT × 100%) and spongy tissue loosened ratio(SR = TST/LT × 100%) of leaf anatomical structure, root to shoot ratio(RSR), leaf transpiration rate(Tr), instantaneous water use efficiency(WUEi), and carbon isotopic composition(δ13C) of the20 shrub species through field experiments. Correlation analysis and principal component analysis were performed on the 19 variables and indices. Important findings Different shrubs had different mechanisms of drought tolerance. In this study, the characteristics of drought tolerance were mainly categorized into 6 types, involving modifications of(1) root systems,(2) leaf anatomical structure,(3) leaf pattern, and(4) biomass allocation, or via(5) low water-consumption and(6) high WUEi. Different genera or different tree species within the same genus clearly differed in drought tolerance. The species of the genus Hippophae were relatively poorly tolerant to drought, whereas several shrubs including Potentilla fruticosa, Berberis julianae, Caragana arborescens, Spiraea salicifolia and Hippophae rhamnoides ssp. mongolica occurred to be more drought tolerant than other shrub species investigated in this study. On the other hand, there were highly significant correlations among the characteristics of root systems and among characteristics of leaf anatomical structure. The results of principal component analysis on 19 variables and indices showed that TRL, TRSA, TRV, TRTN, FRL, FRSA, FRV, FRTN, CT, TPT, TST and WUEi could be effective indicators of drought tolerance of shrubs in the Qinghai-Xizang Plateau. In addition, the drought tolerance of shrubs had a close connection with their origin of collections; the shrubs collected from Xining prefecture in Qinghai Province were more drought tolerant than those from Tianshui Prefecture in Gansu and Lasa Prefecture in Xizang.

Spatial pattern analysis of dominant species in Exochorda giraldii community in Xingtang Temple of Taiyue Mountains, Shanxi, China

Aims The Exochorda giraldii community is a secondary shrubland developed following destruction of warm temperate and deciduous broad-leaved forests. The objective of this study was to explore the distribution and in- ter-relationships of dominant species in E. giraldii communities in Taiyue Mountains, Shanxi, China. Methods Based on the vegetation survey data on a 50 m × 50 m plot, point pattern analysis (O-ring) and fractal analyses (including box-counting dimension analysis, information dimension analysis and correlation dimension analysis) were performed to determine the spatial patterns of dominant species in a E. giraldii community. Important findings In the E. giraldii community, most of the dominant species showed the characteristics of aggregated distribution at smaller scales. However, Periploca sepium and Spiraea salicifolia showed an aggrega- tion distribution at all scales. With increases in scale, the distributions of E. giraldii and Forsythia suspensa changed from aggregation to random and to uniform. Based on the point pattern analysis, the dominant species in the E. giraldii community showed aggregation distribution characteristics at different scales. The box-counting dimension analysis indicated that the ability of dominant species to occupy the space in the E. giraldii community was in the order of E. giraldii > F. suspensa > S. salicifolia > P. sepium. The information dimension analysis in- dicated that the degree of changes in pattern intensity of dominant species with scale in the E. giraldii community was in the order of P. sepium > S. salicifolia > E. giraldii > F. suspensa. The correlation dimension analysis showed that the spatial correlations of dominant species in the E. giraldii community was in the order of P. sepi- um > E. giraldii > F. suspensa > S. salicifolia. On a smaller scale, the E. giraldii population showed aggregated distribution; the F. suspensa population and the E. giraldii population had a positive correlation; the S. salicifolia population and the E. giraldii population had a positive correlation; the P. sepium population and the E. giraldii population had a negative correlation. Point pattern analysis and fractal analyses produced consistent results, re- vealing the spatial distribution patterns of secondary shrubs following destruction of the warm temperate and de- ciduous broad-leaved forests.

국지적으로 분포하는 식물에 대한 기후 및 환경변수 영향

Climate is generally accepted as one of the major determinants of plants distribution. Plants are sensitive to bioclimates, and local variations of climate determine habitats of plants. The purpose of this paper is to identify the factors affecting the distribution of narrow-range plants in South Korea using National Survey of Natural Environment data. We developed species distribution models for 6 plant species using climate, topographic and soil factors. All 6 plants were most sensitive to climatic factors but less other factors at national scale. Meliosma myriantha, Stewartia koreana and Eurya japonica, distributed at southern and coast region in Korea, were most sensitive to precipitation and temperature. Meliosma myriantha was mostly effected by annual precipitation and precipitation of driest quarter, Stewartia koreana was effected by annual precipitation and elevation, and Eurya japonica was affected by temperature seasonality and precipitation of driest quarter. On the other hand, Spiraea salicifolia, Rhododendron micranthum and Acer tegmentosum, distributed at central and northern inland in Korea, were most sensitive to temperature and elevation. Spiraea salicifolia was affected by mean temperature of coldest quarter and annual mean temperature, Rhododendron micranthum and Acer tegmentosum were affected by mean temperature of warmest quarter and elevation. We can apply this result to future plant habitat distribution under climate change.

Spiraea salicifolia: a new plant host of “Candidatus Phytoplasma ziziphi”-related phytoplasma

Spiraea salicifolia is widely grown in China as an ornamental plant, and its roots and young leaves have many medical uses. On the campus of Northwest A&F University, we observed diseased S. salicifolia plants that had yellowed, dwarfed, deformed leaves and other symptoms resembling diseases caused by phytoplasma. This study was aimed at determining the causal agent of the disease. On the basis of phytoplasma-specific DNA amplification by PCR, a phytoplasma infection of S. salicifolia was confirmed. The phytoplasma was related to “Ca. Phytoplasma ziziphi” according to RFLP and phylogenetic analyses. This report is the first of phytoplasma infection of S. salicifolia in China.

만덕산일대의 관속식물 분포 특성

The vascular plants in the Mt. Manduk was listed 560 taxa composed of 110 families, 345 genera, 488 species, 1 subspecies, 67 varieties and 4 forms. Based on the list of the rare plants by the Forest Research Institute, 4 taxa were recorded in the studied areas; Lilium distichum (Preservation priority order; No. 159), Tricyrtis dilatata (No. 97), Aristolochia contorta (No. 151) and Prunus yedoensis (No. 110). Based on the list of Korean endemic plants, 12 taxa were recorded; Cephalotaxus koreana, Carex okamotoi, Lilium amabile, Populus tomentiglandulosa, Salix purpurea var. japonica, Pseudostellaria multiflora, Prunus yedoensis, Stewartia koreana, Forsythia koreana, Paulownia core ana, Weigela subsessilis and Aster koraiensis. Based on the list of approved for delivering overseas of plants, 7 taxa were recorded; Carex okamotoi, Lilium distichum, Aristolochia contorta, Vaccinium oldhami, Paulownia coreana, Asperula lasiantha and Saussurea seoulensis. Specific plants by floral region were total 32 taxa; Prunus yedoensis in class V, Wistaria floribunda in class IV, 5 taxa (Girardinia cuspidata, Spiraea salicifolia, Acer palmatum, Stewartia koreana, Asperula lasiantha) in class III, 3 taxa (Potentilla dickinsii, Viola tokubuchiana var. takedana and Caryopteris incana) in class II and 22 taxa (Pinus koraiensis, Hosta capitata, Chloranthus japonicus, Salix glandulosa, Juglans mandshurica, etc.) in class I. The naturalized plants in the surveyed sites were 14 families, 36 genera, 44 species, 2 varieties, 46 taxa and naturalization rate was 8.2% of all 560 taxa of vascular plants. Wild plants disturbing ecosystem like Ambrosia artemisiifolia var. elatior have been increasing. Therefore, continuous control and conservation measures are needed on the ecosystem of Mt. Manduk.

Effects of scale‐dependent factors on herbaceous vegetation patterns in a wetland, northern Japan

Herbaceous vegetation was examined in an Otanoshike wetland in northern Japan to clarify the relationships between vegetation patterns and environmental factors with different scales. Alders (Alnus japonica) have recently invaded and might modify the herbaceous vegetation. In total, 150 50 × 50 cm plots were established on the transitional areas between alder thickets and grassy marshland. Cover was measured for the vascular plant taxa, and canopy area, number of stumps, number of mounds, water depth, elevation difference, litter thickness, soil organic matter, and soil pH were measured in each plot. TWINSPAN cluster analysis classified four vegetation groups: (i), grasslands represented by Phragmites australis, Trientalis europaea, Lythrum salicaria, and Hosta rectifolia; (ii), Calamagrostis langsdorfii, and Polygonum thunbergii grasslands with Spiraea salicifolia; (iii), reed swamp dominated by Phragmites australis, and (iv), marshland dominated by Carex lyngbyei. Canonical correspondence analysis indicated that water depth primarily divided vegetation groups 1–2 and 3–4. Alder established in drier sites mostly by re‐sprouting, and the canopy affected light and soil conditions on the ground surface. The second axis of canonical correspondence analysis was related to the canopy area and soil pH, and explained the vegetation differentiation between groups 1 and 2, and groups 3 and 4. In conclusion therefore, scale‐dependent or hierarchical variables affected the vegetation patterns in different ways, that is, the herbaceous vegetation was first differentiated by water depth that was corresponding to alder establishment on a large scale, and subsequent light and soil conditions were second determinants on a small scale.

Vegetation, hydrology, and development of a coastal mire in Hokkaido, Japan, affected by flooding and tephra deposition

Mires in coastal lowlands in Hokkaido, northern Japan, have repeatedly been affected by flooding events and tephra (aerially transported volcanic ejecta) deposition during their development. Vegetation, hydrology, and stratigraphy of Kiritappu Mire in eastern Hokkaido were investigated along two transects and are discussed in relation to disturbance by mineral deposition. The vegetation pattern showed little relation to past geologic events. Five plant communities, two of which (A and C) could be further divided into subgroups, were distinguished (A, Alnus japonica - Spiraea salicifolia community; B, Sasa chartacea community; C, Myrica gale var. tomentosa - Sphagnum fuscum community; D, Carex lyngbyei community; E, Carex subspathacea - Aster tripolium community). Water levels, pH, electric conductivity, and ionic composition of groundwater and surface water were measured in communities A-C. Mean water levels were similar in communities A and C; in community B, it was lower. The pH was higher in community A than in communities B and C. Ion concentrations were influenced by sea water at some sites. Plant macrofossils and ash contents of 31 cores were analysed. Sedge roots were the dominant peat component, often mixed with remains of Phragmites australis, Sphagnum spp., and Polytrichum juniperinum var. strictum. Ash contents were high, and up to nine different mineral layers consisting of tephra, sand, silt, and clay were detected. In some cases, mineral deposition induced changes in the macrofossil composition of the peat. However, in a greater number of cases, no changes in the macrofossil composition were found at the mineral layers, and most shifts were not related to mineral deposition.Key words: mire, vegetation, hydrology, disturbance, flooding, tephra.

The impact on the senjogahara ecosystem of extreme run‐off events from the river Sakasagawa, Nikko National Park

AbstractDuring high run‐off events the river Sakasagawa carries extremely large quantities of alluvial materials which are deposited in the north east corner of the Senjogahara moor.This study was initiated to examine the effects, both recent and historic, that this periodic and catastrophic inundation has had on the ecology of this area. It also questions the potential importance of alluvial deposition on the conservation of the moor as a whole. From the data presented it is clear that the present day vegetation of the north east corner of the moor represents a mosaic of vegetation reflecting differential levels of damage to the plants, deposition of alluvial material and the establishment of erosion channels in a space‐time continum. The results indicate that Malus Toringo and Salix integra can survive in the areas outside the heaviest flood damage, whereas Ulmus Davidiana var. japonica, Betula platyphylla var. japonica and Larix Kaempferi are quite sensitive to flooding. Similarly Sasa nipponica var. nana is intolerant of even light alluvial deposition in contrast to Lonicera caerulea var. emphyllocalyx and Spiraea salicifolia which are also still dominant beyond the zone of major alluvial deposition.

OBSERVATIONS ON A CYCLIC FLUCTUATION IN THE LEAF SERRATIONS OF SPIRAEA SALICIFOLIA, AND ON THE ASYMMETRY OF THE LEAF

A shoot of Spiraea salicifolia bears serrate leaves in a spiral sequence. The number of serrations on any single undamaged leaf margin can be counted without ambiguity. Let us define (Fig. i) left and right margins as seen from the adaxial side and let the numbers of serrations upon these margins be L and R respectively. These numbers have been recorded for several shoots from a cultivated clone, taking the counts for successive leaves along the stem. We will consider first the behaviour of the total (R -+ L).