Latitudinal pattern of mountain vegetation zonation in southern and eastern Asia

A new scheme of altitudinal and latitudinal vegetation zonation is proposed for eastern Asia. The latitudinal patterns of mountain vegetation zonation show a clear boundary at ca. 20°–30° N. For the tropical mountains south of 20° N, the altitudinal series includes tropical lowland, tropical lower montane, and tropical upper montane zones. For the temperate mountains north of 30° N, the series includes temperate lowland, temperate lower montane, and temperate upper montane zones. The mountains located between 20° and 30° N show a transitional zonation pattern; the lower two zones are comparable to the lower two of the tropical zonation (tropical lowland and tropical lower montane), and the upper two zones are comparable to those of the temperate zonation (temperate lower montane and temperate upper montane). The tropical upper montane zone is not found north of 20°–30° N, while the tropical lower montane zone reaches down to sea level and constitutes the temperate lowland zone. Thus the zonation between 20° and 30° N includes tropical lowland, tropical lower montane/temperate lowland, temperate lower montane, and temperate upper montane zones. The latitudinal series of lowland rain forests follows the scheme of climatic division into tropical, subtropical/warm-temperate, cool-temperate and cold-temperate, with a shift of the respective life forms, evergreen, evergreen notophyllous, deciduous, and evergreen needle-leaved. The tropical lower montane forest can be correlated to the horizontal subtropical/ warm-temperate zone. The temperate altitudinal and latitudinal zonations above 30° N are correlated and show an inclined parallel pattern from high altitudes in the south to low altitudes down to sea level in the north.     

Influence of altitude on the distribution pattern of flora in a protected area of Western Himalaya

IntroductionDistribution pattern and diversity of flora was compared along an altitudinal gradient using the stratified random sampling design for identifying major plant communities of Kedarnath Wildlife Sanctuary of Garhwal Himalaya, India. The reconnaissance of flora is presented, along with the analysis of the distribution of species, genera, and families within five (5) altitudinal zones. Kedarnath Wildlife Sanctuary which is situated in the Indian Himalayas harbours a rich variety of flora and fauna. The Himalayas are recognized for diverse vegetation distributed over a wide range of topographical conditions.ResultsThe analysis of diversity within five (5) altitudinal zones was carried out and a total of 324 plant species, representing 219 genera belonging to 92 families, were found. The dominant family was Asteraceae; the co-dominant family was Rosaceae, followed by Lamiaceae and Ranunculaceae. Eight (8) families were observed in all the altitudinal zones, while forty (40) families were observed in a single altitudinal zone, and the remaining forty-four (44) families were found in more than one (1) altitudinal zone. Most of the tree species were contagiously distributed, but a few of them were randomly distributed in all the altitudinal zones. The shrubs and herbs were contagiously distributed in all the altitudinal zones. The correlation analysis (P < 0.05) between altitude and number of species showed that altitude is negatively correlated with tree (r = −0.96), shrub (r = −0.61), and herb species (r = −0.20). As per the cluster analysis of tree layer, altitudinal zone - III (2450–2650 m) and altitudinal zone - IV (2900–3100 m) were found most similar. Altitudinal zone–V (3350–3550 m) was found to be dissimilar from the other zones for herbs.ConclusionsAlthough species composition varies with altitude, but there is a complex relationship between species richness and altitudinal gradient. A decreasing pattern in both species richness and family richness for trees, shrubs and herbs, was recorded with increasing altitude. The predominant factors underlying this variability in plant species and biogeography appear to be climatic and specific to each taxonomic group.     

A survey of the fauna of streams on Mount Elgon, East Africa, with special reference to the Simuliidae (Diptera)

The stream fauna of Mt Elgon is described from collections taken during a 6-week visit. Collections were mainly made on the cultivated slopes below the belt of montane forest, and although stations were concentrated on the western sides of the mountain sufficient were worked elsewhere to show that there was little or no geographical variation of the fauna. The streams are physically diverse but faunistically rather uniform, with a few genera dominating the fauna throughout the entire range of altitude investigated. Most of the other taxa showed evidence of altitudinal limitation which may be attri-buted to the pronounced temperature gradients of the mountain's streams. As the species of Simuliidae and adult Elminthidae could be reliably distinguished their distributions were studied in greater detail. The Simuliidae showed a pronounced zonation of species, the majority being confined to narrow ranges of altitude below the forest margin. Factors considered to influence their distribution were principally altitude (temperature), current speed and, to a lesser extent, stream size. The influence of these factors on the distribution of adult Elminthids was less marked, although all species showed at least an upper or a lower limit of altitude, and more than half the commoner species a preference for a particular stream type. Taxonomic knowledge of African freshwater faunas allows few groups to be identified beyond the genus, and with this limitation the Elgon stream fauna is found to differ in only minor respects from the faunas of other highland areas in Central Africa.     

Spatial zonation of macrobenthic fauna in Zhanjiang Mangrove Nature Reserve, Guangdong, China

The spatial zonation of macrobenthic fauna in the core region of Zhanjiang Mangrove Nature Reserve was studied with two transects vertical to the shoreline. The first transect was near Deyao Village where three faunal zones of the mangrove swamp could be divided into the following types from the high tide part to the low tide part: the Assiminea lutea-Uca arcuata-Paracleistostoma crassipilum zone, the Cleistostoma dilatatum-Macrophthalmus erato-Littoraria melanostoma zone, and the Paracleistostoma depressum-Cerithidae cingulata zone. Mollusck and crustacean exhibited the highest individual density in this transect. Mollusck mainly influenced the dynamics of community biomass as well as the species diversity index. In the second transect near Hongzhai Village, the following four faunal zones could be determined: the Littoraria melanostoma-Pseudoringicula sinensis-Ceratonereis burmensis zone, the Assiminea lutea-Cleistostoma dilatatum zone with a dominant species belonging to the Ellobiidae, Upogebia sp.-Paracleistostoma depressum zone, and the Metaplax sheni-Cerithidae cingulata zone. The crustacean showed the highest individual density in this transect. Similar to the Deyao transect, dynamics of community biomass and the species diversity index of the Hongzhai transect were mainly influenced by mollusck. By hierarchical clustering and nonmetric multidimensional scaling, the macrobenthic fauna communities could be divided into three and four groups in the Deyao and Hongzhai transects, respectively. These groups corresponded to different types of vegetation of the mangrove swamp. Taken together, our observations indicated that the spatial zonation of the macrobenthic fauna was mainly affected by the characteristics of the mangrove community, sediment characteristics and the tidal line.     

Spatial zonation of macrobenthic fauna in Zhanjiang Mangrove Nature Reserve, Guangdong, China

The spatial zonation of macrobenthic fauna in the core region of Zhanjiang Mangrove Nature Reserve was studied with two transects vertical to the shoreline. The first transect was near Deyao Village where three faunal zones of the mangrove swamp could be divided into the following types from the high tide part to the low tide part: the Assiminea lutea-Uca arcuata-Paracleistostoma crassipilum zone, the Cleistostoma dilatatum-Macrophthalmus erato-Littoraria melanostoma zone, and the Paracleistostoma depressum-Cerithidae cingulata zone. Mollusck and crustacean exhibited the highest individual density in this transect. Mollusck mainly influenced the dynamics of community biomass as well as the species diversity index. In the second transect near Hongzhai Village, the following four faunal zones could be determined: the Littoraria melanostoma-Pseudoringicula sinensis-Ceratonereis burmensis zone, the Assiminea lutea-Cleistostoma dilatatum zone with a dominant species belonging to the Ellobiidae, Upogebia sp.-Paracleistostoma depressum zone, and the Metaplax sheni-Cerithidae cingulata zone. The crustacean showed the highest individual density in this transect. Similar to the Deyao transect, dynamics of community biomass and the species diversity index of the Hongzhai transect were mainly influenced by mollusck. By hierarchical clustering and nonmetric multidimensional scaling, the macrobenthic fauna communities could be divided into three and four groups in the Deyao and Hongzhai transects, respectively. These groups corresponded to different types of vegetation of the mangrove swamp. Taken together, our observations indicated that the spatial zonation of the macrobenthic fauna was mainly affected by the characteristics of the mangrove community, sediment characteristics and the tidal line.     

Distribution of Leguminosae tree species in different altitudinal levels along the Atlantic Rain Forest in the Brazilian coast

The Atlantic Forest is one of the most threatened tropical forests in the world. Leguminosae, by its great richness and dominance among arboreal stratum elements, is of major importance in the floristic composition and structure of this forest. We investigated the distribution of legume species on an altitudinal gradient to find out the altitudinal zones with higher richness of species; the altitudinal zones with greater floristic similarity; the possible presence of species that may be exclusive to certain vegetation types and the altitudinal amplitudes of those species, as well as the occurrence of species substitution along the altitudinal gradient. Therefore, thirty one studies conducted in different altitudinal levels between 5° S and 29° S were analyzed. A matrix with 142 tree species distributed in altitudinal zones (every 100 m) from sea level to 2100 m was built. The greatest species richness was observed in the Submontane Forest (50–500 m) with 92 species. The cluster analysis revealed a strong dissimilarity of the 1400–2100 m (Upper Montane) and 0–10 m zones (Restinga Forest). The Submontane and the Montane Forest share the highest number of species (38 ssp.). Forty species are unique to Submontane. Substitution of species was verified. Some species have their preferred habitat located at a specific altitudinal amplitude, as is the case of Inga laurina and I. subnuda (0–10 m), I. lanceifolia and Machaerium scleroxylon (800–1200 m). The Leguminosae, although well adapted to the first colonization and establishment of diverse environment, was poorly represented above 1500 m altitude.     

Zonal transition of evergreen,deciduous, and coniferous forests along the altitudinal gradient on a humid subtropical mountain,Mt. Emei,Sichuan, China

Altitudinal zonation of evergreen, deciduous and coniferous forests on Mt. Emei (3099 m asl, 29°34.5' N, 103°21.5' E), Sichuan, China was studied to understand the transition of vegetation zonation from tropical to temperate mountains in humid Asia. On the basis of quantitative data on floristic composition and community structure sampled at ten plots selected in different altitudes on the eastern slope of the mountain, forest zonation and the inter-relationships among different life-forms of trees in each zonal forest community were studied quantitatively. Three forest zones were identified physiognomically along the altitudinal gradient, viz. (i) the evergreen broad-leaved forest zone (660–1500 m asl), (ii) the mixed forest zone (1500–2500 m asl), and (iii) the coniferous forest zone (2500–3099 m asl). Great compositional changes were observed along elevation, and the zonal forest communities were characterized by their dominants and floristic composition. Maximum tree height decreased from 33 m at lower middle altitude (965 m asl) to 13 m near the summit (2945 m asl). There was no apparent deciduous forest zone along the altitudinal gradient, but true mixed forests of three life-forms (evergreen, deciduous, and coniferous) were formed around 2000–2500 m asl. Patches of deciduous forest were found in a lower part of the mixed forest zone, particularly on scree slopes, between 1450 m and 1900 m asl. These patches were dominated by the Tertiary relic deciduous trees, such as Davidia involucrata, Tetracentron sinense, and Cercidiphyllum japonicum var. sinense. High species diversity in the mixed forest zone resulted from the overlapping of different life-forms at middle altitudes, which is partly due to wider variety of temperature-altitude correlations. A comparison of the altitudinal zonation with the other east Asian mountain vegetation clarified that Mt. Emei is located exactly at the ecotone between tropical and temperate zonation types in eastern Asia.     

Structural comparison of tropical montane rain forests along latitudinal and altitudinal gradients in south and east Asia

Geographical patterns of altitudinal zonation, floristic composition, and structural features of tropical montane rain forests were examined along latitudinal gradients in south and east Asia. On equatorial mountains, the tropical montane rain forests occur above 1000 m. Toward middle latitudes, they come farther down and reach sea level at c. 35° N. Thus, the forests are equivalent to the subtropical rain forests of the latitudinal, horizontal zonation series. They exhibit gradual changes in floristic composition and structure along both altitudinal and latitudinal gradients. On equatorial mountains, they are divided into three types, i.e. tropical lower montane, upper montane, and subalpine forests. The three tree regeneration types, having emergent, sporadic and inverse-J type stem-diameter class frequency distributions, coexist in the lower montane forests, but the upper and subalpine forests display only the inverse-J type species with a few species of the sporadic type. Toward the northern latitudinal limit, the distinction between the three tropical montane forest zones in equatorial mountains becomes less clear. This can be explained by temperature conditions: on equatorial mountains, a temperature sum of 85° C months which controls the upper limit of the lower montane forests, and a coldest month mean temperature of-1° C which controls the evergreen broad-leaved trees, appear at c. 2500 and c. 4000 m respectively. The altitudinal range between 2500 m and 3800 m, which is the upper forest limit, is covered by upper montane and subalpine forests. On the other hand, at the latitudinal northern limit, the tropical upper montane and subalpine forests cannot exist because the above mentioned two temperature conditions occur at nearly the same point. Thus, at the northern latitudinal limit of the tropical montane forests, the three zones of equatorial mountains amalgamate into a single subtropical lowland forest community. This is due to the seasonal temperature climate in middle latitudes in, e.g., central Japan and central China.A part of this paper was presented as an oral presentation at the Vth International Congress of Ecology, Yokohama 23–30.8.1990.     

Altitudinal zonation of the southern flank of western and Eastern Tannu-Ola Ranges: Principal types of plant communities

Three types of altitudinal zonation are described on the southern flank of the Tannu-Ola Ranges. Principal types of plant communities are characterized for each zone. Classification scheme is established.     

A mangrove community in the New Hebrides, south-west Pacific

A general survey of the mangal at Port Stanley, Malekula, New Hebrides, the most extensive mangal in the archipelago, was conducted over an 11-day period in September/October 1971. Seventeen species of true mangrove tree and mangrove associates were recorded. As is characteristic of mangal, this flora was distributed in a zonal pattern, four zones being recognized. Certain anomalies in zonation were attributed to a recent episode of crustal uplift. The aquatic component of the fauna was dominated by molluscs (26 species) and Crustacea (20 species). The terrestrial vertebrate fauna consisted of 4 species of reptiles, 21 birds and 5 mammals.
The mangrove community at Port Stanley is an integral part of that of the Indo-West Pacific region. However it is much restricted in number of species, and reasons for this are suggested: distance from Malesia, lack of fresh water, and shallow soils with little silt deposition. Faunal impoverishment is clearly associated with floral impoverishment.     

深圳福田红树林区底栖大型动物群落的空间分带及灌污的可能影响

本文自１９９１年４月至１９９３年１月对深圳福田红树林中底栖大型动物的空间分带及灌污的可能影响进行了研究。结果表明,该红树林湿地中主要出现的底栖动物为拟沼螺科,黑螺科,汇螺科,沙蟹科,方蟹科和弹涂鱼科种类。红树区内底栖动物从高潮位到低潮位可分为３个群落分布带：亮泽拟沼螺带;拟黑螺－褶痕相手蟹带;弧边招潮－印尼拟蟹守螺－刻纹拟沼螺带。群落的分带可能主要由潮位线,食物适应性及底质结构因素决定。林前泥滩底栖动物种类多样性最大,生物量最高。林内动物群落则表现出低种类多样性,高种群个体数的特点。群落总栖息密度的变化基本上由软体动物所主导。生活污水排灌对红树林中底栖大型动物的影响不明显,仅在排污口端引起少数污水动物种类的出现及群落总生物量轻微的升高。     

New findings on the geographic distribution of the verrucarum group (Diptera: Psychodidae) in Colombia

The incrimination of sand flies belonging to verrucarum species group in the leishmaniasis transmission underscores the need for a detailed information on the geographical distribution of these species. The current listing adds 34 new records that extend significantly the knowledge of the geographical distribution of the verrucarum group in Colombia. The most important new records pertain to Lutzomyia spinicrassa in the tropical dry forest of the Atlantic coast, Lutzomyia ovallesi in the Orinoco and Amazon River watersheds regions of Colombia, and the sympatric occurrence of Lutzomyia spinicrassa and Lutzomyia quasitownsendi in the eastern chain of the Andes mountains. Additionally, the municipal and altitudinal distributions are compiled for 19 new species recorded for Colombia. The series townsendi of the verrucarum group generally restricted to premontane and lower montane zones based on distribution data on Lutzomyia longiflocosa, L. quasitownsendi, Lutzomyia sauroida, L. spinicrassa, Lutzomyia torvida, Lutzomyia townsendi and Lutzomyia youngi. The series verrucarum is distributed from the tropical lowland to the montane zones, and includes species with wide geographical range (Lutzomyia evansi, Lutzomyia columbiana, L. ovallesi, Lutzomyia nuneztovari, Lutzomyia nevesi), and species of highly endemic distribution (Lutzomyia andina, Lutzomyia disiuncta, Lutzomyia moralesi, Lutzomyia antioquiensis). Members of the series pia (Lutzomyia pia, Lutzomyia limafalcaoae) and the series serrana (Lutzomyia serrana) occur from the tropical lowlands to the lower montane zones. The altitudinal divergences may be intrinsically tied to speciation process, especially as it relates to the climatic and geologic events that have affected the flora and fauna of the Andean region.     

Spatial Distribution of the Nematode Fauna and Production of Three Nematodes (Tobrilus gracilis,Monhystera stagnalis,Ethmolaimus pratensis) in the Profundal of Piburger See (Austria, 913 m a.s.l)

The species composition and the spatial distribution of the nematode fauna of Piburger See is discussed briefly. The study then concentrates on the three species (Tobrilus gracilis, Monhystera stagnalis, Ethmolaimus pratensis) which form the lake's profundal nematode fauna between depths of roughly 8 and 13 meters. This profundal fauna is separated by a distinct metalimnetic abundance minimum from the very diverse littoral community. In addition to taxonomic and ecological considerations, the zonation of the three species within their main habitat is described, and life cycles cohort production as well as annual production are evaluated from the field data. Total annual nematode production within the profundal habitat (8–13 m) in Piburger See amounts to 11.6 kg per hectare. 65 % of which are contributed by T. gracilis, 22 % by M. stagnalis and 13 % by E. pratensis. For the whole area under observation (6 to 13.5 m, including the scarcely populated border zones) mean annual nematode production is 7 kg per hectare.     

Altitudinal effects on habitat selection of dung beetles (Scarabaeoidea: Aphodiidae) in the northern Iberian peninsula

The effects or vegetation cover on the abundance and species richness of dung beetles (Aphodiidae) were examined in three altitudinal zones: lowland (520–600 m), mid-altitude (950–963 m) and highland (1230–1275 m). Pitfall traps baited with fresh cattle dung were placed in three vegetation types at each altitudinal zone: forest, heathland and pasture. Species richness was lower in forests than in the other vegetation types. The total abundance of beetles also varied with vegetation type, but the effect was dependent on altitude. Number of individuals was higher in pasture at highlands and in heathland and forest at mid-altitude and lowlands. An altitudinal dependence of distribution of individuals between vegetation types was also found for the more abundant species in the study area. These results could be explained if the local distribution of individuals between vegetation types was determined by microcli-matic factors, mainly temperature. Differences in altitude between sites are associated with temperature changes, determining the habitat selection of species at each altitude.     

Distribution patterns and chorological analysis of fish fauna of the Arctic Region

Chorological structure of ichthyofauna of the Arctic Region is described. Distribution patterns of 504 fish-like vertebrates and fish species are characterized. One hundred and eighty-nine range types are defined, which are combined into eight main categories: 1—Arctic; 2—Atlantic-Arctic; 3—transitional subarctic zone of Atlantic sector; 4—Pacific-Arctic; 5—transitional subarctic subarctic zone of Pacific sector, 6—Pacific-Atlantic (amphiboreal); 7—bipolar; 8—continental (fresh and brackish waters). Arctic and boreal regions are bordered by transitional (subarctic) zones, which are the areas of intermutual penetration of faunas. The distribution of most fish species that penetrate into to the Arctic Region from the southern areas is limited by these transitional zones. The benthic fish species prevail in the group of autochthonous Arctic species (which includes 64 species or 14% of marine fauna). The demersal fauna of the Arctic preudoabyssal is presented by endemic species. Ten variations of amphiboreal distribution patterns are revealed. Three areas may be defined within the Atlantic-subarctic zone in regard to the fish fauna and range types, i.e., Labrador-Greenland region, the Barents Sea region, and Icelandic (transitional) region.     

四川鞍子河国家级自然保护区及邻近地区蚁科昆虫区系分析

为揭示四川鞍子河国家级自然保护区及邻近地区蚂蚁区系特征,2016年6—7月采用样地调查法研究了该区域的蚂蚁区系.结果显示:共采集蚂蚁6亚科32属62种;在世界动物地理界中,分布于东洋界的共32属,东洋界分布种最多(62种),新热带界种最少(3种);在中国动物地理区中,西南区种最多(62种),蒙新区种最少(4种);在种的...     

Stream hydraulics as a major determinant of benthic invertebrate zonation patterns

SUMMARY. 1. Studies on the zonation of benthic fauna in fourteen streams situated in a variety of latitudes from Alaska to New Zealand have been evaluated.
2. We suggest that physical characteristics of flow ('stream hydraulics') are the most important environmental factor governing the zonation of stream benthos on a world-wide scale.
3. From the source to the mouth of a stream, zones of transition in stream hydraulics' occur, to which the general pattern of stream invertebrate assemblages can be related. In these zones benthic community stability and resilience must be different from those upstream and downstream of the hydraulic transition zones.     

Altitudinal zonation of evergreen broad-leaved forest on Mount Lopei,Taiwan

Abstract. Evergreen broad-leaved forest was studied in a transect on the northwestern slope of Mount Lopei in order to reveal altitudinal zonation in structure and floristic composition and the decisive environmental factors. 20 plots of 20 m × 20 m at altitudes from 540 m to 1320 m were analysed. 144 woody species were found. The results of a DCA ordination clearly pointed to a single dominant altitudinal gradient. Nevertheless, wind-exposure associated topography was found to account for additional variation for a given altitudinal range. Along the altitudinal gradient, four dominance-based forest types were recognized. Tree density, species diversity and evenness of the four types differed significantly but total basal area and tree volume were not significantly different. The 95 % turnover range for woody species as measured by the Community Coefficient was calculated as 1030 m, and the 50 % turnover range as 238 m. For the understorey, the change in species composition with altitude was less obvious. Species population structures of 57 sufficiently abundant species revealed four characteristic patterns, but most species showed a good fit to the negatively exponential or power function distribution and thus appeared to have good reproduction and regular recruitment. Both ANOVA and Redundancy Analysis (RDA) showed that significant differences among forest types were found for most soil variables. Organic C, exchangeable Na and K tended to increase with altitude, while pH and available N showed a reverse trend. There was little evidence that the differences in soil pH and available N were responsible for the variation in forest growth.     

Multi-scale altitudinal patterns in species richness of land snail communities in south-eastern France

Aim Species richness is an important feature of communities that varies along elevational gradients. Different patterns of distribution have been described in the literature for various taxonomic groups. This study aims to distinguish between species density and species richness and to describe, for land snails in south‐eastern France, the altitudinal patterns of both at different spatial scales. Location The study was conducted on five calcareous mountains in south‐eastern France (Etoile, Sainte Baume, Sainte Victoire, Ventoux and Queyras). Methods Stratified sampling according to vegetation and altitude was undertaken on five mountains, forming a composite altitudinal gradient ranging from 100 to 3100 m. Visual searching and analysis of turf samples were undertaken to collect land snail species. Species density is defined as the number of species found within quadrats of 25 m². Species richness is defined as the number of species found within an elevation zone. Different methods involving accumulation curves are used to describe the patterns in species richness. Elevation zones of different sizes are studied. Results Eighty‐seven species of land snails were recovered from 209 samples analysed during this study. Land snail species density, which can vary between 29 and 1 species per 25 m², decreases logarithmically with increasing altitude along the full gradient. However, on each mountain separately, only a linear decrease is observable. The climatic altitudinal gradient can explain a large part of this pattern, but the great variability suggests that other factors, such as heterogeneity of ground cover, also exert an influence on species density. The altitudinal pattern of species richness varies depending on the spatial resolution of the study. At fine resolution (altitudinal zones of 100 m) land snail species richness forms a plateau at altitudes below 1000 m, before decreasing with increasing altitude. At coarse resolution (altitudinal zones of 500 and 1000 m) the relationship becomes linear. Main conclusions This study reveals that land snail species density and land snail species richness form two different altitudinal patterns. Species density exhibits strong variability between sites of comparable altitude. A large number of samples seem necessary to study altitudinal patterns of species density. Species density decreases logarithmically with increasing altitude. Above a critical altitudinal threshold, this decrease lessens below the rate seen in the first 1500 m. Different methods exist to scale‐up species density to species richness but these often produce different patterns. In this study, the use of accumulation curves has yielded a pattern of species richness showing a plateau at low altitude, whereas simple plotting of known altitudinal ranges from single mountains would have produced stronger mid‐altitudinal peaks. This study shows that not only factors such as temperatures and habitat heterogeneity, but also an ecotone effect, are responsible for the observed patterns.     

滇西北昆虫区系特点

本文对滇西北昆虫区系特征进行了分析。滇西北昆虫区系具有以下特点:古北区与东洋区种类过渡与交混明显;新发现的种类及特有种和狭布种十分丰富;原始古老的种类多;垂直分布明显。如以江河分水岭为界,尚可分为怒江、澜沧江、金沙江3个小区。滇西北典型的东洋区系成份,一般在海拔3000m以下地区,海拔3000m以上则以古北区系成份为主。