Leaf domatia in Korean plants: floristics,frequency, and biogeography

Leaf domatia, specialized structures on the undersides of leaves, appear to promote mutualism between plants and those mites that protect leaves from pathogenic fungi and small herbivorous arthropods. Their occurrence was surveyed on 425 plant species (368 native species and 57 species introduced from other regions of northeastern Asia), comprising 177 genera and 59 families of woody Dicotyledonae in the Korean flora. Domatia, primarily of tuft or pocket forms (84% of species), were present in vein axils on leaves of 152 species (36%) within 66 genera (37%) and 39 families (66%). Overall, we report leaf domatia in nine new families and 25 additional genera. Mites, primarily from families or suborders (e.g., Acaridida, Phytoseiidae, Tydeidae) in which arboreal representatives are primarily fungivorous or predaceous, were found in domatia on leaves of 78% of all species sampled. Domatia frequency depended upon both growth form and habit of species. They were especially common among tree species (55%), but less so on shrubs (20%) and woody vines (22%). Domatia were much more frequent on species of deciduous plants (40% of those sampled) than on evergreen species, of which only 10% had leaf domatia. This difference was consistent across a number of local deciduous and broadleaf evergreen forests in South Korea. The high frequency of leaf domatia in this survey indicates that plant-mite mutualism may be widespread in Korean plant communities. The floristic affinities of plants with domatia in Korea to those in other regions of East Asia, eastern North America, and Europe suggest that these plant-mite associations characterize the temperate broadleaf deciduous forest biome in the Northern Hemisphere.     

OCCURRENCE OF PREDATORY AND FUNGIVOROUS MITES IN LEAF DOMATIA

Domatia are small invaginations and hair tufts usually found at vein junctions on the undersides of leaves in many woody dicots. Domatia of 32 plant species (of worldwide origin from 18 families) growing in California, Hawaii, and Costa Rica were examined for mites. Domatia of 31 of 32 (97%) of these plants contained mites, and 24 of 32 (75%) contained mite eggs. Mites were found within the domatia of 48% of the sampled leaves. The domatia of 26 of 31 (84%) plants had mite species considered beneficial (primarily in the families Phytoseiidae and Tydeidae, but also Bdellidae, Cheyletidae and Stigmaeidae), while 6 of 31 (19%) had mite species considered harmful (Tenuipalpidae and Eriophyidae). Based on these findings (and in part upon Lundström's 1887 domatia theory), we hypothesize the existence of a widespread facultative mutualism between plants with leaf domatia and beneficial mites: leaf domatia serve as shelters and nurseries for mites which in turn eat phytophagous arthropods and pathogens using the plants. This proposed mutualism could be of importance to agriculture since domatia are known to occur in some crop plants, including coffee, grape, and walnut.     

Leaf domatia and mites on Australasian plants: ecological and evolutionary implications

Leaf domatia, specialized chambers in the vein axils on the underside of leaves of many plant species, have remained an enigma for over a century. In this study we show a strong association between foliar domatia and mites in 37 plant species in Australasia. Overall, mites accounted for 91% of the arthropods observed in domatia. Across all species, a median of 51% of domatia were occupied and 71% of leaves showed mite evidence in domatia. The level of mite association did not depend on domatia type (pit, pouch, pocket, or tuft) or provenance (Papua New Guinea, Queensland, Victoria, or New Zealand). Mite association with domatia commonly varied between plant species, between individuals within species, and between shoots within individuals. The leaf developmental stage probably explains much of the variation in association for many of these species. The presence of a variety of life history stages of mites within domatia indicates that these structures act as shelters for development and reproduction. Furthermore, in 12 of 13 plant species examined, domatia concentrate mites in particular locations on the leaf. Mite taxa that we classify as largely predaceous (e.g. phytoseiids, stigmaeids and tydeids) or fungivorous (e.g. acarids and oribatids) were most common in domatia and dominated the association in 21 of 24 plant species in which the relative abundance of herbivorous, fungivorous and predaceous groups was quantified. We evaluate hypotheses that explain the role of leaf domatia, including non-functional hypotheses (e.g. architectural constraints), physiological function (e.g. gas exchange and water uptake), bacterial symbiosis and antagonistic and mutualistic associations with mites. Our quantitative results confirm anecdotal accounts of mite association with leaf domatia and are most consistent with Lundströem's century-old hypothesis of plant-mite mutualism in which leaf domatia billet predaceous and fungivorous mites that prey on plant enemies. Leaf domatia are widespread among woody angiosperms and abundant in many temperate and tropical regions of Australasia. Mites, an ancient group of arthropods whose diversity and abundance parallels that of insects, are likely to be important selective agents on terrestrial plants. Our results (1) indicate that mite-domatia association represents a relationship of comparable scope to plant-ant associations mediated by specialized plant structures such as extrafloral nectaries, food bodies and specialized domatia; (2) suggest that sociality is not a necessary prerequisite for widespread and diverse mutualisms between arthropods and plants; and, (3) extend the diversity of organisms that produce specialized mite ‘houses’ from lizards, and wasps and bees to woody angiosperms.     

Does microhabitat structure affect foliar mite assemblages?

1. Habitat structure is an important factor influencing population dynamics and trophic organisation of terrestrial invertebrates. The phylloplane zone on vascular plant leaves is topographically complex, containing a multitude of microhabitats such as leaf hairs, lesions, and structural refugia such as domatia, which may modify interactions between resident invertebrate communities, colonisers, and subsequent trophic relationships. Leaf domatia are small indentations on the underside of leaves and are often inhabited by potentially beneficial mites and other arthropods. 2. This study investigated the relationship between domatia availability and foliar mite assemblages in contrasting habitats (native forest, plantation forest, and pasture) using a standard test plant (the endemic New Zealand shrub Coprosma lucida, J.R. & G. Forst.). 3. Diverse woody native vegetation types supported higher numbers of mite species than either plantation forest or pastoral grasses. The highest number of mite species occurred in the native forest (63%), plantation forest (38%), and pastoral grasses (25%). In the native vegetation type, experimental C. lucida leaves with domatia supported higher mite densities, greater colonisation success, and more diverse mite assemblages than those without domatia. Mite assemblages within the pastoral site were significantly different from the other two vegetation types. Only one fungivorous mite species, Orthotydeus californicus, occurred compared to five mite species in native and plantation forests. 4. This study indicated that foliar mite assemblages in native vegetation on experimental C. lucida shrubs are influenced by domatia availability, resident foliar mites, and local mite assemblages.     

Benefits associated with the domatia mediated tritrophic mutualism in the shrub Coprosma lucida

The fitness benefits of plant structural adaptations that increase the effectiveness of fungivores against leaf pathogenic fungi are poorly understood. In a 12‐month field experiment, we investigated the effect of domatia on mite density, the role of these mites in limiting leaf fungi, and the associated effects on plant fitness in the endemic New Zealand shrub, Coprosma lucida. The presence of domatia on mite density was controlled using combinations of domatia blocking, sham blocking, mite addition and mite control using miticide. Limiting access to domatia reduced mite density and increased the proportion of leaves without mites. Mite families represented were predominantly fungivorous/detritivorous (97.2%), and predaceous (2.6%); herbivorous mites were absent. Mites significantly reduced fungal hyphae, fungal spores and pollen, but the effect was surface‐(upper/lower) and density‐dependent with the greatest reduction in fungi occurring over low mite densities. Fungal hyphae reduced leaf longevity, but were associated with increased production of new leaves. Hyphae density on old leaves was negatively correlated with the number of domatia produced on new leaves. New leaves in the mite reduction treatment had slightly reduced levels of carbon but not nitrogen. High levels of fungal infection on the lower surface increased the number of fruit fascicles per shoot, however on the upper surface where fungi were reduced by mites, hyphae density was negatively related to reproduction. The data support a limited interpretation of a fitness benefit for plants with domatia. While domatia increased mite density, control of fungi by mites occurred at lower average densities than supported by plants without functioning domatia. We suggest the primary function of leaf domatia in this mutualism is to increase the probability of a leaf‐level beneficial mite presence rather than to maximise mite density. Many mites are not necessarily better than few mites, but some mites are better than none.     

Domatia morphology and mite occupancy of Psychotria horizontalis (Rubiaceae) across the Isthmus of Panama

Leaf domatia are small plant structures in vein axials on the undersides of leaves that are often inhabited by mites of several species. The mites are presumed to benefit the plant because they are predatory or fungivorous. The domatia are thought to provide the mites shelter from predators and changes in relative humidity, and in exchange, the mites protect the plant from small herbivores and fungal spores. Differences in relative humidity can affect food availability, changing the interaction between plants and mites. We examined domatium morphology of the shrub Psychotria horizontalis (Rubiaceae) and its associated mite diversity at three sites along the rainfall gradient of the Isthmus of Panama, during the dry and wet seasons. The dry forest had a domatium morphology consistent with providing greater desiccation protection, with trichomes and a smaller domatium opening relative to domatium size (size/opening ratio). Additionally, this size/opening ratio was significantly higher in the dry season than in the wet season at all three sites. Mite diversity was highest at the intermediate rainfall site with a large degree of overlap with the other sites, whereas the dry site and wet site shared few mite species. More fungivorous mites were present in the moist forests and more facultative feeders on fungal spores and small mites in the dry forest. The average mite size at each site matched the average domatium size at each site. The dry forest had small mites in small domatia, whereas the moist forests had larger mites in larger domatia. While these data are primarily observational, the site and seasonal differences in domatium morphology and mite diversity are consistent with two main hypotheses: (1) that protection from changes in humidity would be particularly important when humidity was low, such as in the dry forest and during the dry season (2) more fungivorous mites would be found in domatia of the moist forests. The data presented here further highlight the close adaptive relationship between leaf domatia on plants and the mites that inhabit them.     

Annual photosynthetic activities of temperate evergreen and deciduous broadleaf tree species with simultaneous and successive leaf emergence in response to altitudinal air temperature

To explain why the composition of evergreen and deciduous forests changes along air temperature gradients, we measured several traits of single leaves from temperate deciduous and evergreen broadleaf trees with simultaneous and successive leaf emergence growing at different altitudes in the field. The parameters included seasonal net photosynthetic rate, longevity, mass per area, nitrogen content, and photosynthetic nitrogen-use efficiency. With decreasing altitude, the leaf longevity of deciduous broadleaf trees increased, whereas the maximum net photosynthetic rate decreased. In contrast, leaf longevity of evergreen broadleaf trees decreased, whereas the minimum net photosynthetic rate in winter increased. Along the air temperature gradient, the annual production of deciduous trees with simultaneous leaf emergence may be constant, because the integrated lifetime net photosynthetic rate (ILNPR) of a single leaf changed little. In comparison, deciduous trees with successive leaf emergence may show enhanced annual production with increasing air temperature, by increasing the total leaf number per branch and tree under an extended growing season. Temperate evergreen broadleaf tree species may also show increased annual production with increasing air temperature by sufficiently raising the number of the first-year leaves to the total leaves of branch and tree, which is accelerated by raising the integrated first-year net photosynthetic rate of the single leaf, despite little change in the ILNPR. With increasing air temperature from cool-temperate to warm-temperate zones, evergreen broadleaf tree species gain an advantage of the annual production over deciduous broadleaf tree species with simultaneous leaf emergence.     

Plants,mites and mutualism: leaf domatia and the abundance and reproduction of mites on Viburnum tinus (Caprifoliaceae)

Associations between mites and leaf domatia have been widely reported, but little is known about their consequences for either plants or mites. By excising domatia from leaves of the laureltinus, Viburnum tinus L. (Caprifoliaceae), in the garden and laboratory, we showed that domatia alter the abundance, distribution, and reproduction of potential plant mutualists. Over 4 months, leaves with domatia on six garden shrubs had 2–36 times more predatory and microbivorous mites, and more mite eggs than leaves without domatia. However, this effect varied among plants and was weaker on one shrub with few mites on its leaves. Domatia also influenced the distribution of mites on leaves. A significantly higher fraction of mites, representing all life stages, was found in vein axils of leaves with domatia than in vein axils on leaves without domatia. Single-leaf experiments in the laboratory showed that domatia enhanced reproduction by the predatory mite, Metaseiulus occidentalis, especially at low relative humidity (30–38%). When domatia were removed, oviposition was reduced significantly only at low relative humidity, suggesting that domatia provide mites with refuge from environmental extremes on the leaf surface. Moreover, the use of domatia by predatory mites may reduce the impact of some plant enemies. In two experiments where prey consumption was measured, M. occidentalis ate significantly higher percentages of the eggs of the two-spotted spider mite (Tetranychus urticae). Our results are consistent with the viewpoint that mite-domatia associations are mutualistic. By directly aiding and abetting the third trophic level, plants with leaf domatia may increase the efficiency of some predaceous and microbivorous mites in consuming plant enemies.     

Biotic interactions of mites, plants and leaf domatia

Leaf domatia, minute structures that typically house mites and other small arthropods, are produced by an impressive number of plants; however, their role in mediating plant-mite mutualism has only recently been elucidated. New evidence indicates that domatia function primarily as refuges for beneficial mites against predators. The presence of domatia therefore results in more beneficial mites on leaves, fewer pathogen attacks and reduced leaf herbivory. Unexpectedly, herbivorous mites are specialized domatia inhabitants of some plants. By providing refuges for herbivores, however, domatia may stabilize interactions between predator and their mite prey and thereby reduce the chances of herbivore outbreaks. Understanding the ecological mechanisms that promote beneficial interactions between mites and plants could have important implications for pest management.     

Do leaf domatia mediate a plant–mite mutualism? An experimental test of the effects on predators and herbivores

1. Leaf domatia are tiny structures in leaf vein axils that are widespread among plant taxa and have been described to be typically inhabited by predatory and fungivorous mites. The mutualism hypothesis for the function of leaf domatia predicts that predatory and/or fungivorous mites benefit from having a favourable place to take refuge and reproduce and that plants benefit indirectly from reduced herbivory and/or pathogen attack.
2. The effect of leaf domatia on populations of predatory and herbivorous mites was examined for avocado, Persea americana . In separate experiments, domatia were added to leaves of a variety of avocado plants lacking domatia (Hass) and domatia were blocked on a domatia-bearing variety (Toro Canyon).
3. In two out of the five experiments conducted, domatia-bearing plants had significantly higher numbers of predatory mites compared with controls. Although herbivore numbers were consistently lower on plants with domatia than on plants without domatia, in no case did the presence of leaf domatia result in a statistically significant decrease in herbivorous mite populations.
4. These results suggest that domatia may frequently benefit predatory mites, however, indirect effects on herbivorous mites may not commonly exist or may be too difficult to detect.     

Associations between mites and leaf dornatia

Associations between mites and leaf domatia are widespread, abundant and probably ancient. Recent research has shown that mites commonly shelter, develop and reproduce within domatia on plants in many geographic regions, from the tropics to the temperate zone, and most of these mites belong to predaceous or fungivorous taxa. Of hypotheses offered to explain these associations, protective mutualism is most consistent with the reported characteristics and patterns of mitedomatia association.     

我国温带山地森林48种常见树种叶片重量-出叶强度的关系

叶片是植物的主要光合器官, 其质量与数量的权衡关系体现植物对环境的适应策略。在全球气候变化的背景下, 研究叶片质量与数量关系有助于理解植物对环境变化的响应趋势。该研究应用标准化主轴回归方法, 探讨了我国温带山地森林中48个常见树种的单叶干重与出叶强度的权衡关系。结果表明, 所有物种以及落叶阔叶林、常绿和落叶阔叶树种、单叶以及亚冠层阔叶树种的单叶干重与出叶强度表现为异速生长关系; 针叶林、针阔混交林、常绿及落叶针叶树种、复叶以及冠层阔叶树种则表现为等速生长关系。研究结果表明, 叶大小和出叶强度并无恒定的权衡关系。     

Host plant manipulation of natural enemies: leaf domatia protect beneficial mites from insect predators

Acarodomatia are small tufts of hair or invaginations in the leaf surface and are frequently inhabited by several taxa of non-plant-feeding mites. For many years, ecologists have hypothesized that these structures represent a mutualistic association between mites and plants where the mites benefit the plant by reducing densities of phytophagous arthropods and epiphytic microorganisms, and domatia benefit the mite by providing protection from stressful environmental conditions, other predaceous arthropods, or both. We tested these hypothesized benefits of domatia to domatia-inhabiting mites in laboratory and growth chamber experiments. In separate experiments we examined whether domatia on the wild grape, Vitis riparia, provided protection against drying humidity conditions or predaceous arthropods to two species of beneficial mite: the mycophagous species Orthotydeus lambi, and the predaceous species Amblyseius andersoni. For both taxa of beneficial mite, domatia significantly increased mite survivorship in the presence of the predatory bug, Orius insidiosus and the coccinellids Coccinella septempunctata and Harmonia varigata. There was no evidence for a protective effect of domatia with a third species of predatory arthropod, lacewing larvae Chrysoperla rufilabris. In contrast, there was no evidence for either species of beneficial mite that domatia provided any protection against low humidity. Thus in this system the primary mechanism by which domatia benefit beneficial mites is by protecting these organisms from other predatory arthropods on the leaf surface.     

亚热带常绿阔叶林和暖温带落叶阔叶林叶片热值比较研究

植物干重热值(GCV)是衡量植物生命活动及组成成分的重要指标之一,反映了植物光合作用中固定太阳辐射的能力。利用氧弹量热仪测定了亚热带和暖温带两个典型森林生态系统常见的276种常见植物叶片的干重热值,探讨了亚热带和暖温带植物热值分布特征,以及不同生活型、乔木类型间植物热值的变化规律。实验结果发现:亚热带常绿阔叶林和暖温带落叶阔叶林叶片热值的平均值分别为17.83 k J/g(n=191)和17.21k J/g(n=85),整体表现为亚热带植物暖温带植物。不同地带性植被的植物叶片热值在不同生活型间表现出相似的规律,其中亚热带常绿阔叶林表现为:乔木(19.09 k J/g)灌木(17.87 k J/g)草本(16.65 k J/g);暖温带落叶阔叶林表现为:乔木(18.41 k J/g)灌木(17.94 k J/g)草本(16.53 k J/g);不同乔木类型间均呈现常绿乔木落叶乔木、针叶乔木阔叶乔木的趋势。落叶阔叶乔木表现为亚热带暖温带,而常绿针叶乔木则呈现亚热带暖温带的趋势。此外,我们对于两个分布区域内的4种针叶树种叶片热值进行了比较,发现华北落叶松(19.32 k J/g,暖温带)杉木(19.40 k J/g,亚热带)马尾松(19.82 k J/g,亚热带)油松(20.95 k J/g,暖温带)。亚热带常绿阔叶林和暖温带落叶阔叶林植物热值的特征及其变化规律,为森林生态系统的能量流动提供了理论基础。     

Seasonal variation in leaf-litter input and leaf dispersal distances to streams: the effect of converting broadleaf riparian zones to conifer plantations in central Japan

Sugi (Cryptomeria japonica D. Don) is one of the most important evergreen coniferous plantation species in Japan. Much of the riparian forest that was originally dominated by deciduous broadleaf trees has been converted into sugi plantations. The present study investigated the seasonality of leaf-litter input and leaf dispersal to streams to assess the effects of converting riparian forest to sugi plantations. The seasonality of leaf-litter input was assessed at three streams in Nagoya University Forest. At one stream dominated by deciduous broadleaf trees, input was limited to autumn. At two streams in a sugi plantation, input was prolonged from autumn to early spring, and was dominated by sugi needles from winter to early spring. These results suggest that sugi plantations alter the seasonality of leaf-litter input from riparian forests and affect stream ecosystems. Leaf dispersal was assessed by considering the relationship between leaf dispersal distance from three forest layers to the stream and leaf-litter input into two streams. The maximum leaf dispersal distance was 26–28 m for deciduous broadleaf trees from mid-October to November and 10–12 m for sugi needles from December to April. Leaf dispersal distance depended on the tree species. Four species of deciduous broadleaf tree showed greater leaf dispersal than that of sugi. The mean weight of individual sugi needles was higher than that of the broadleaf trees’ leaves, and dispersal depended on strong winds in winter and early spring. Although the leaf dispersal distance from the understory was within 2–4 m, it could be a significant source of leaf-litter input to streams.     

贵州施秉喀斯特地区林地土壤甲螨的群落组成及多样性（英文）

【目的】为了解施秉喀斯特地区林地土壤甲螨的分布和群落组成特点,明确中国西南喀斯特地区林地类型对土壤甲螨群落密度、组成和物种多样性的影响,对该区林地土壤甲螨的群落结构及多样性进行了的调查和分析。【方法】2012年8月选取了中国西南施秉喀斯特地区典型生境中的8个样地,每个样地9个取样点,用Berlese-Tullgren装置分离土样24 h。多样性分析采用常见的多样性指数;群落相似性分析采用Jaccard相似性系数(C_J);群落聚类分析分别采用Marczewski Steinhaus 距离(C_ms)和Bray-Curtis距离,应用R 2.11程序进行类平均法聚类。【结果】结果显示,中国西南喀斯特8个样地中土壤甲螨由少数的优势属和数量众多的稀有属组成。其中全菌甲螨属 Perscheloribates (22.48%)和长单翼甲螨属 Protoribates (11.45%)个体数量最为丰富。长单翼甲螨属 Protoribate、上罗甲螨属Epilohmannia、小奥甲螨属 Oppiella、小盾珠甲螨属 Suctobelbella 和盖头甲螨属 Tectocepheus 分布广泛。本区的甲螨组成（属级水平）表现出明显热带和亚热带地区特点。在天然常绿落叶阔叶林中,甲螨的个体数量和种类数较多,但多样性不高,而在人工针叶林中甲螨多样性最高。甲螨群落组成和分布特征多样,异质性高,特别是在天然常绿落叶阔叶林中突出。【结论】研究表明,施秉喀斯特生态系统的不同林分影响甲螨的物种多样性和群落稳定性,天然常绿落叶阔叶混交林是甲螨的“避难所”。     

中国4种典型森林中常见乔木叶片的非结构性碳水化合物研究

植物叶片的非结构性碳水化合物(non-structural carbohydrates,NSC)不仅为植物的代谢过程提供重要能量,还能一定程度上反映植物对外界环境的适应策略。以温带针阔混交林(长白山)、温带阔叶林(东灵山)、亚热带常绿阔叶林(神农架)和热带雨林(尖峰岭)4种森林类型的树种为研究对象,利用蒽酮比色法测定了163种常见乔木叶片可溶性糖、淀粉和NSC(可溶性糖+淀粉)含量,探讨了不同森林类型植物叶片NSC的差异及其地带性变化规律。结果显示：（1）从森林类型上看,植物叶片NSC含量从北到南递减,即温带针阔混交林(170.79 mg/g)>温带阔叶林(100.27 mg/g)>亚热带常绿阔叶林(91.24 mg/g)>热带雨林(80.13 mg/g)。（2）从生活型上看,无论是落叶树还是阔叶树,其叶片可溶性糖、淀粉和NSC含量均表现为：温带针阔混交林>温带阔叶林>亚热带常绿阔叶林>热带雨林;北方森林叶片可溶性糖、淀粉和NSC含量均表现为落叶树种>常绿树种,或阔叶树种>针叶树种。（3）森林植物叶片NSC含量、可溶性糖与淀粉含量比值与年均温和年均降水量均呈显著负相关。研究表明,森林植物叶片可溶性糖、淀粉和NSC含量以及可溶性糖与淀粉含量比值均具有明显的从北到南递减的地带性规律;其NSC含量以及可溶性糖与淀粉含量比值与温度和水分均呈显著负相关的变化规律可能是植物对外界环境适应的重要机制之一。该研究结果不仅为阐明中国主要森林树种碳代谢和生长适应对策提供了数据基础,而且为理解区域尺度森林植被对未来气候变化的响应机理提供新的视角。     

Drought-deciduous behavior reduces nutrient losses from temperate deciduous trees under severe drought

Nutrient resorption from senescing leaves is an important mechanism of nutrient conservation in temperate deciduous forests. Resorption, however, may be curtailed by climatic events that cause rapid leaf death, such as severe drought, which has been projected to double by the year 2100 in the eastern United States. During a record drought in the southeastern US, we studied 18 common temperate winter-deciduous trees and shrubs to understand how extreme drought affects nutrient resorption of the macronutrients N, P, K, and Ca. Four species exhibited drought-induced leaf senescence and maintained higher leaf water potentials than the remaining 14 species (here called drought-evergreen species). This strategy prevented extensive leaf desiccation during the drought and successfully averted large nutrient losses caused by leaf desiccation. These four drought-deciduous species were also able to resorb N, P, and K from drought-senesced leaves, whereas drought-evergreen species did not resorb any nutrients from leaves lost to desiccation during the drought. For Oxydendrum arboreum, the species most severely affected by the drought, our results indicate that trees lost 50% more N and P due to desiccation than would have been lost from fall senescence alone. For all drought-deciduous species, resorption of N and P in fall-senesced leaves was highly proficient, whereas resorption was incomplete for drought-evergreen species. The lower seasonal nutrient losses of drought-deciduous species may give them a competitive advantage over drought-evergreen species in the years following the drought, thereby impacting species composition in temperate deciduous forests in the future.     

Leaf domatia mediate mutualism between mites and a tropical tree

Although associations between mites and leaf domatia have been widely reported, their consequences for plants, especially for natural tree populations, particularly in the tropics, are largely unknown. In experiments with paired Cupania vernalis (Sapindaceae) saplings in a semi-deciduous forest in south-east Brazil, we blocked leaf domatia to examine their effect: (1) on mites and other arthropods, and (2) on damage caused by fungi and herbivorous arthropods. In general, plants with resin-blocked domatia had fewer predaceous mites on leaves than control plants with unaltered domatia, but the total abundances of fungivorous and of phytophagous mites remained unchanged. However, phytophagous eriophyid mites, the most numerous inhabitants of domatia, decreased on leaf surfaces with the blocking treatment. In a second experiment, treated plants lacking functional domatia developed significantly greater numbers and areas of chlorosis, apparently due to increased eriophyid attacks, whereas fungal attack, epiphyll abundance and leaf-area loss were unaffected. This seems to be the first experimental study to demonstrate that leaf domatia can benefit plants against herbivory in a natural system. The possible stabilizing effect of leaf domatia on predator-prey interactions is discussed.     

辽宁东部的主要植被类型及其分布

辽宁东部位于铁岭一营口一线以东地区。北部为山地,属于长白植物区系区。南部为辽东半岛丘陵,属于华北植物区系区,并具有一些耐寒性的亚热带植物。红松(Pinus koraiensis)、沙松(Abies holophylla)—阔叶混交林和油松 (Pinus tabulaeformis)、赤松(P.densiflora)、落叶阔叶林是辽宁东部的地带性植被。但是,目前次生的蒙古栎(Quercus mongolica)林和各类灌丛分布很广。以开原一南杂木一青城子一青椅山线为界把辽东分为两个植被地带：1)北部为温带针叶阔叶混交林地带;2)南部为暖温带落叶阔叶林地带。在暖温带落叶阔叶林地带内,熊岳一青椅山线的东南部为亦松栎林亚地带,西北部为油松栎林亚地带。