Selective burning of forest vegetation in Canton Ticino (southern Switzerland)

Abstract

Detailed knowledge of factors controlling fire regime is a prerequisite for efficient fire management. We analyzed the fire selectivity of given forest vegetation classes both in terms of fire frequency and fire size for the present fire regime (1982–2005) in Canton Ticino (southern Switzerland). To this end, we investigated the dataset in four categories (all fires, anthropogenic winter fires, anthropogenic summer fires, and natural summer fires) and performed 1000 random Monte Carlo simulations on frequency and size. Anthropogenic winter and summer fires have a similar selectivity, occurring mostly at low elevations in chestnut stands, broadleaved forests, and in the first 50 m from the forest edge. In winter half of the fires in chestnut stands are significantly larger than 1.0 ha and the average burnt area in some coniferous forests tends to be high. Lightning fires seem to occur more frequently in spruce stands and less often in the summer‐humid chestnut and beech stands and the 50–100 m buffer area. In beech forests, in mixed forests, and in the spruce stands affected by natural fire in summer, the fires tend to be small in size. The selectivity observed, especially the selectivity of anthropogenic fires in terms of fire frequency, seems to be also related to geographical parameters such as altitude and aspect, and to anthropogenic characteristics such as closeness to roads or buildings.     

Aspen Increase Soil Moisture,Nutrients, Organic Matter and Respiration in Rocky Mountain Forest Communities

Development and change in forest communities are strongly influenced by plant-soil interactions. The primary objective of this paper was to identify how forest soil characteristics vary along gradients of forest community composition in aspen-conifer forests to better understand the relationship between forest vegetation characteristics and soil processes. The study was conducted on the Fishlake National Forest, Utah, USA. Soil measurements were collected in adjacent forest stands that were characterized as aspen dominated, mixed, conifer dominated or open meadow, which includes the range of vegetation conditions that exist in seral aspen forests. Soil chemistry, moisture content, respiration, and temperature were measured. There was a consistent trend in which aspen stands demonstrated higher mean soil nutrient concentrations than mixed and conifer dominated stands and meadows. Specifically, total N, NO₃ and NH₄ were nearly two-fold higher in soil underneath aspen dominated stands. Soil moisture was significantly higher in aspen stands and meadows in early summer but converged to similar levels as those found in mixed and conifer dominated stands in late summer. Soil respiration was significantly higher in aspen stands than conifer stands or meadows throughout the summer. These results suggest that changes in disturbance regimes or climate scenarios that favor conifer expansion or loss of aspen will decrease soil resource availability, which is likely to have important feedbacks on plant community development.     

Contribution of ambient ozone to changes in Scots pine defoliation. Step II of Lithuanian studies

This study aimed to explore if changes in peak ozone (O3) concentrations may reinforce the phytotoxic effects of air concentration of acidifying compounds and their deposition, as well as unfavorable climatic factors on pine crown defoliation. Forty-eight pine stands with more than 8000 sample pine trees have been monitored annually. The impact of sulfur dioxide (SO2) on pine defoliation was found to be the most significant. The impacts of peak O3 concentrations, acid deposition, and amount of precipitation were considerably lower, whereas the impact of air temperature, the least. Contribution of peak O3 concentrations to the integrated impact of acid deposition and amount of precipitation on pine defoliation was most significant, whereas the contribution to the impact of acidifying air compounds, mainly SO2, was the least. No synergetic effect between peak O3 concentrations and high temperature during vegetation period was detected.     

The Sibyla model and development of beech forests affected by air pollution

The paper deals with the health status, production and structure of autochthonous beech stands in the eastern part of the Krkonoše Mts. (Czech Republic). The region was affected by increased air pollution load due to long-range SO₂ transmission from the late 1970s to the early 1990s. In 1980, five research plots were established in long unmanaged beech stands at an optimum stage. Tree coordinates and initial biometrical measurements were made in 1980 and repeated in 2005. The defoliation of individual trees was monitored every year (ICP Forests principles). The actual stand development is compared with the model development worked out by the Sibyla growth simulator in variants with a model of natural mortality and with entering a real mortality of trees. Differences between the stand characteristics of actual and simulated development of forest stands suggest some production losses. The reason to the losses can be seen in the long-term impact of air pollution in the first decade of monitoring and its after-effects on soil quality and worsening health condition of stands. The anticipated acceleration in the onset of the phase of stand disintegration under the influence of air pollution load was not demonstrated.     

Selection harvest in temperate deciduous forests: impact on herb layer richness and composition

Herb layer richness and composition of four forest types and three different management treatments were investigated in 16 deciduous forest stands of northern Germany. Specifically, we compared the species richness and composition occurring in mature forest stands that were single-tree and group selection harvested to those in unmanaged reference stands. Mean species richness of all herb layer species increased significantly with increasing harvest severity. When analyzing plant groups separately, it became obvious that this overall pattern was not consistent. While a negative relationship was detected between vernal herb richness and harvest severity, group selection harvest significantly increased species richness of summer herbaceous forest species and generalists. Woody species richness was not related to harvest severity. Community composition of the spring aspect was not significantly affected by selection harvest, whereas herb layer species composition in the summer aspect differed significantly among the three harvest treatments. A dominance of highly competitive shrub and generalist species was confined to some parts of the most intensively harvested stands. Overall, our results indicate that the herb layer community was not severely adversely affected by selection harvest at the intensities used in the studied stands. It is suggested that selection harvest systems may be feasible tools with which to conserve local forest vascular plant diversity and at the same time to meet the demand for timber products. However, information about forest history and the implementation of the selection harvest system are basic requirements when interpreting the results of studies on understorey response to selection harvest.     

Trend in ambient ozone and an attempt to detect its effect on biota in forest ecosystem. Step I of Lithuanian studies

The presented study aimed to explore the relationships between ambient ozone (O3) and tree defoliation, specific diversity, and abundance of soil microarthropods, stream macroinvertebrates, and small mammals (mainly rodents) in order to test the hypothesis that changes in the considered objects of the forest ecosystem could be related to changes in ambient O3, concentration of which is below critical level. The observations were carried out from 1994 at three integrated monitoring stations. The obtained data revealed that only peak O3 concentrations (from 125-215 microg x m(-3)) had significant effect on changes in the considered components of forest biota.     

Weather or weathering? Growth of Nothofagus dombeyi on volcanic soils differing in nitrogen and phosphorus concentrations

Aims We tested whether—in addition to weather conditions—the concentrations of nitrogen and phosphorus in the substrate have an effect on the radial stem increment of Nothofagus dombeyi trees in old-growth forest stands on volcanic soil at the western slopes of the Andes in South-Central Chile.Methods We took soil samples and tree increment cores from five proximate sites (1000–1300 m a.s.l.) that are located in the volcanic region of the Conguillío National Park and differ in the age of the substrate (Miocene—3500 years B.P.) and in its concentrations of nitrogen (N) and phosphorus (P). The soil samples were also analysed on their concentrations of other plant mineral nutrients, carbon (C) and nitrogen isotope ratios (δ 15 N). Tree-ring widths and the stem basal area increment (BAI) were related to climate parameters. In selected tree rings, the stable isotope ratios of carbon (δ 13 C) and oxygen (δ 18 O) were determined and related to growth and climate parameters.Important findings Consistent with theory, the soils on the oldest substrate showed the highest (least negative) δ 15 N values, but mineral N was the only nutrient whose concentration exhibited a straightforward (increasing) relationship with increasing substrate age. The BAI was largest on the soil with the highest concentration of plant-available P. In contrast to BAI, tree-ring chronologies did not differ among the study sites. However, tree-ring chronologies and BAI exhibited significantly positive correlations with summer precipitation, and negative correlations, with summer (December) temperature. A negative correlation was found between δ 13 C and precipitation anomalies in the growing season (November–March). We interpret the negative correlations between growth and temperature, and between δ 13 C and δ 18 O in the tree rings, as an impairment of net carbon assimilation by anomalously warm weather conditions during the growing season. We conclude that the growth of N. dombeyi is mainly affected by high temperature and low precipitation in spring and summer irrespective of the substrate's age, and enhanced by higher concentrations of plant-available P in the soil. Our results may be representative of N. dombeyi stands on volcanic substrate within their principal distribution range along the Andes of South America.     

海南岛尖峰岭热带山地雨林的群落结构特征

本文讨论了海南岛尖峰岭热带山地雨林乔木层的群落结构的一些基本特征,结果表明：热带山地雨林种类成份复杂,生物多样性指标高,原始林的Shannon－Wiener多样性指数（乔木层）为5．8—6．3,而更新林则在4．5—4．8之间,均匀度指标均在81％以上,反映了优势种群不明显的特点。群落组成种类以热带成份占优势,达80％以上。乔木层的胸径和树高分布均合理;群落组成种群的频度分布不同于RaunKiaer提出的频度定律,而是以A＞＞B＞C＞DE→0（原始林）和A＞＞B＞C＞D→0＜E（天然更新林）的形式存在,并且以A级频度占绝对优势,反映了热带林在世界植被中的特殊性。     

Quantifying the canopy nectar resource and the impact of logging and climate in spotted gum Corymbia maculata forests

Nectar in tall forest canopies is a significant, but unquantified resource for Australian fauna. We investigated the impact of logging on nectar production in the canopy of spotted gum Corymbia maculata in southern New South Wales. In addition, we quantified the magnitude of canopy nectar production and how this varied with climate over 2 years. In 2005 flowers were bagged on large and small trees in replicate recently logged, regrowth and mature forest. Neither logging history nor tree size significantly affected overnight nectar production per flower, although there was a significant interaction. When nectar production was scaled up to the forest stand (incorporating flower and tree density) mature forest produced almost 10 times as much sugar per ha as recently logged forest, with regrowth being intermediate. Under current forest practices at the compartment scale, the difference between mature forest and recently logged forest was reduced to a factor of two times. One distinctive characteristic of C. maculata nectar in 2005 was its high sugar content (40–60%) compared with the concentrations measured in 2003 (～18%). Nectar was only slightly depleted in unbagged flowers in 2005 when flowering was unusually extensive. We estimated that, on average, mature spotted gum forest produced a vast resource of nectar overnight: 35 000 Kj ha^?1. Flowers measured in 2003 provided a strong contrast with only occasional stands of trees flowering, much less sugar per flower early in the morning and unmeasurable quantities by mid‐morning, indicating that nectar was limiting. Measurements at sites in 2003 indicated that regrowth sites could be more productive than mature forest; however, few sites were measured. We suggest that management should focus mitigations on poor flowering years when the nectar resource is limiting. Models of nectar production collated over both years, using climate and site variables, indicated nectar volumes and sugar concentration respond differently to environmental conditions. Predicting the nectar resource, which is made up of both components, was most consistently related to recent conditions that were unfavourable to foliage production.     

Seasonal variation in soil CO<Subscript>2</Subscript> efflux in evergreen coniferous and broad-leaved deciduous forests in a cool-temperate forest,central Korea

We measured the soil surface CO₂ efflux (R _S) from January 2005 to December 2006 in two neighboring stands in Gwangneung Forest, central Korea: evergreen coniferous forest (Abies holophylla, stand A) and broad-leaved deciduous forest (Quercus-dominated, stand Q). Regarding seasonal variation, R _S rate was low during the winter and early spring months in each stand and peaked in late July [1170 (stand A) and 1130 (stand Q) in 2005, and 1000 (stand A) and 740 (stand Q) mg CO₂ m⁻² h⁻¹ in 2006]. R _S rate was higher in stand A than in stand Q during most of the growing season. The pattern of summer rainfall differed between 2005 and 2006. R _S rate for both stands was suppressed significantly by the droughts in June 2005 and September 2006. After the heavy rainfall of July 2006, R _S rate was lower than in July 2005 in both stands, but this decrement was much greater in stand Q than in stand A. In midsummer (August) 2006, under higher soil temperature (ST) and lower soil water content (SWC) conditions than in August 2005, R _S rate of stand A was lower than that in August 2005, whereas stand Q showed no marked change. The exponential relationship between ST and R _S accounted for approximately 91–97% of the R _S variability in each stand and in each year. In stand A, the application of a second-order polynomial function indicated a significant correlation between SWC and R _S when the soil was warm (ST > 15°C). Our results suggest that the seasonality of R _S is strongly affected by the pattern of summer rainfall even in an Asia monsoon climate regime. In addition, the vegetation type (i.e., evergreen coniferous forest vs. broad-leaved deciduous forest) plays a significant role in response of R _S to various environmental fluctuations such as drought, heavy rainfall, and hot-dry condition.     

Interpretation of nutrient concentrations inPinus radiata foliage at Belanglo state forest

Foliage from six youngPinus radiata trees on a phosphorus limited site were chemically analysed annually for ten years. Nutrient differences were found between trees and between years. The pre-sampling period rainfall (last month of summer plus all autumn) accounted for 68% of variance of annual phosphorus concentrations and pre-sampling rainfall and age together accounted for 83%. The figures for calcium and nitrogen were 65% and 56% respectively. Testing the relationships in older stands of the same forest indicated age was only critical in stands which were less than about 16 years of age. When the information was used in conjunction with a site survey which showed Site Index to be related to phosphorus status, it was shown that the required concentrations of phosphorus needed to be modified according to rainfall. These relationships are discussed in relation to the use of foliage analysis for determining fertilizer requirements.     

Diversity of bryophyte vegetation in some forest types in Estonia: a comparison of old unmanaged and managed forests

The bryophyte vegetation of 3 pairs of unmanaged and managed forest stands, representing Oxalis drained peatland, Aegopodium and Oxalis forest site type, were compared. The total number of bryophyte species in unmanaged stands was 74 and that in managed stands 54. Out of the 20 species occurring only in unmanaged forests, 9 grow on decaying wood, and 3 on trunks or bases of big trees; 13 of them were hepatics. In unmanaged forests 11 hemerophobic species were recorded altogether. Although the difference in substrate and species diversity between unmanaged and managed stands is not statistically significant, in unmanaged forests more substrates characteristic for an old-growth stand are available, and the percentage of species preferring dryer habitats or prolonged humidity is a bit higher than in managed forests; the percentage of species associated with better illuminated habitats is higher in managed forests. Analysis of classification structure of the bryophyte layer synusia shows that the number of societies is also higher in unmanaged forests. This is associated with more numerous microhabitats; the average light and humidity indices calculated for every society, confirm this conclusion. The large discrepancy in bryophyte layer classification structure in old-growth and managed forests of the same forest site type is manifested not so much by species content in synusia as by their abundance proportions. The larger diversity of classification units in unmanaged forests is also seen at the synusia facies level; four of nine facies are confined exclusively to unmanaged stands. This is a strong argument for the informativeness of bryophyte layer classification structure for purposes of indication and monitoring as well.     

官山白颈长尾雉活动区域海拔高度的季节变化及其影响因素

2005年7月至2006年12月,采用无线电遥测的方法在江西官山国家级自然保护区内对5只白颈长尾雉（Syrmaticus ellioti）的活动区域进行了跟踪监测,结合GIS技术和样方法分析其活动区域的海拔高度随季节变化的影响因素。结果表明：海拔400-600m为白颈长尾雉全年最适活动带,其主要活动区域的海拔高度呈现明显的季节变化：夏秋季最高,春季次之,冬季最低。水源是其冬季喜欢在低海拔区域活动的最主要原因;而距林缘距离、灌木数量、灌木种数、灌木盖度等与增加食物丰富度和隐蔽度相关的因子是促使它们在春季和夏秋季倾向于在高海拔区域活动的主要因素。     

Foliar and wood chemistry of sugar maple along a gradient of soil acidity and stand health

The decline of sugar maple (Acer saccharum Marsh.) in forest of north-eastern North America is an important environmental issue. In this study, relationships between, soil, wood and foliar chemistry were assessed for 17 stands distributed within a large area of the Quebec sugar maple forest and that were growing on soils with a strong gradient of acidity and base saturation. There were many significant relationships between variables describing the acid-base status of the top-B soil (Ca and Mg concentrations, exchangeable acidity and base saturation) and Ca and Mn concentrations and Ca/Mn and Mg/Mn in tree tissues. Manganese was the element that showed the strongest inverse non-linear relationships with top-B soil base saturation with variance explanation of 71 and 65%, for wood and foliage, respectively. The 17 sites were divided in two groups according to their level of decline. The declining stands had significantly higher wood Mn and Mg concentrations and lower Ca/Mn ratios and significantly higher foliar Mn and lower Ca and Al concentrations. It was impossible to determine if these differences were a cause or a symptom of sugar maple health. However, the increase in Mn concentrations in tree tissues with increasing soil acidity, as well as the higher Mn concentrations in declining as compared to healthy stands suggest that Mn, as well as low Ca availability, could be an important contributing factor in the sugar maple decline.     

Nutrient dynamics along a precipitation gradient in European beech forests

Precipitation as a key determinant of forest productivity influences forest ecosystems also indirectly through alteration of the nutrient status of the soil, but this interaction is not well understood. Along a steep precipitation gradient, we studied the consequences of reduced precipitation for the soil and biomass nutrient pools and dynamics in 14 mature European beech (Fagus sylvatica L.) forests on Triassic sandstone. We tested the hypotheses that lowered summer precipitation (1) is associated with less acid soils and (2) a reduced accumulation of organic matter on the forest floor, and (3) reduces nutrient supply from the soil and leads to decreasing foliar and root nutrient concentrations. Soil acidity, the amount of forest floor organic matter, and the associated organic matter N and P pools decreased to about a half from wet to dry sites; the C/P and N/P ratios, but not the C/N ratio, of forest floor organic matter were reduced as well. Net N mineralization and P and K pools in the mineral soil did not change with decreasing precipitation. Foliar P and K concentrations (beech sun leaves) increased while N remained constant, resulting in decreasing foliar N/P and N/K ratios. Estimated N resorption efficiency increased toward the dry sites. We conclude that a reduction in summer rainfall significantly reduces the soil C, N and P pools but does not result in decreasing foliar N and P contents in beech. However, the decreasing foliar N/P ratios towards the dry stands indicate that the importance of P limitation for tree growth declines with decreasing precipitation.     

Nitrogen fixation in hardwood forests of the northeastern United States

Summary Nitrogen-fixing activity in hardwood forests of the northeastern United States occurred in wood litter, greater than 2 cm in diameter. Activity in large dead wood was independent of species, in the case of deciduous wood litter, but was restricted to partially decayed wood with a high moisture content. Maximum rates of activity were observed in the summer months, minimum rates in the winter. Evidence from six stands of varying ages showed that fixation in large wood litter occurred in only 25% of the samples assayed.Fixation was highest in the youngest, 4 years, and oldest, over 200 years, stands; being about 2 kg/ha/yr. The quantity of nitrogen fixed appears to be related to the biomass of dead wood. Large amounts of wood litter in the youngest stands were from slash left after cutting. As the supply of slash is exhausted by decay, nitrogen fixation decreases, with a low around year 20. Fixation then gradually increases as natural thinning adds wood to the litter compartment.Apparently, the amount of nitrogen fixed in dead wood the first 20 years following clearcutting can only replace a modest fraction of the amount lost as a result of the cutting and product removal. Finally, the results indicate that nitrogen fixation in wood litter does not equal nitrogen fixation in a northern hardwood forest calculated using a mass balance approach, suggesting that additional nitrogen inputs exist.     

Monitoring of Ips typographus and Pityogenes chalcographus: influence of trapping site and surrounding landscape on catches

• 1 The influence of trapping site (i.e. fresh clear‐cuts) characteristics and habitat amount (i.e. area of stands that may hold breeding material) in the surrounding landscape on catches of the bark beetles Ips typographus (L.) and Pityogenes chalcographus (L.) in pheromone‐baited flight‐barrier monitoring traps was studied.
• 2 For the two species, the study investigated: (i) the extent of the variation in catches among trapping sites; (ii) the extent of this variation that can be explained by models including trapping site characteristics (clear‐cut size, percentage of spruce in the cut stand, altitude) and habitat amounts in the surrounding landscape; and (iii) the spatial scale at which beetles respond to the habitat amount in the landscape.
• 3 The variation in catches among trap sites was 15‐fold larger for I. typographus than for P. chalcographus. There was a positive relationship between the catches of I. typographus and (i) the percentage of the surrounding landscape covered by mature spruce forest at radii 500–4000 m and (ii) the percentage of spruce in stands cut when the clear‐cuts used as trapping sites were created. For P. chalcographus, only the second relationship could be demonstrated.
• 4 Thus, for monitoring of I. typographus: (i) several trapping sites per landscape are required; (ii) the amount of mature spruce forest around trapping sites needs to be considered when choosing trapping sites; and (iii) the trapping sites need to be standardized with respect to the percentage of spruce in the cut stand when fresh clear‐cuts are used. For P. chalcographus, fewer trapping sites per landscape are required and only the percentage of spruce in the cut stand needs to be considered.

     

Former land use affects the nitrogen and phosphorus concentrations and biomass of forest herbs

The colonization rates of understorey plants into forests growing on former agricultural land differ remarkably among species. Different dispersal and recruitment largely account for the contrasting colonization rates, but different effects of the soil legacies of former agricultural land use on plant performance may also play a role. Seven herbaceous forest species were sampled in paired post-agricultural and ancient forest stands to study whether land-use history has an effect on the aboveground nutrient concentrations (N, P and N:P ratios) and biomass of forest herbs and, if so, whether slow and fast colonizing species respond differently. Results showed that P concentrations were significantly affected by former land use with higher concentrations in the post-agricultural stands. N concentrations were unaffected and N:P ratios were significantly higher in the ancient stands. Nutrient concentrations varied considerably among species, but the variation was unrelated to their colonization capacity. Six out of the seven species had higher biomass in the post-agricultural stands relative to the ancient stands, and the degree to which the species increased biomass was positively related to their colonization capacity, i.e., the fast colonizing species showed the strongest increase. Such differential responses to past land use may contribute to the contrasting colonization capacity of forest plants. Land-use history thus affected both the nutrient concentrations and biomass of forest herbs, and only the biomass response was related to colonization capacity.     

Communities of ground-living spiders in deciduous forests: Does tree species diversity matter?

The relationships between species diversity and ecosystem functions are in the focus of recent ecological research. However, until now the influence of species diversity on ecosystem processes such as decomposition or mineral cycling is not well understood. In deciduous forests, spiders are an integral part of the forest floor food web. In the present study, patterns of spider diversity and community structure are related to diversity of deciduous forest stands in the Hainich National Park (Thuringia). In 2005, pitfall trapping and quantitative forest floor sampling were conducted in nine plots of forest stands with one (Diversity Level 1), three (DL 2) and five (DL 3) major deciduous tree species. Species richness, measured with both methods, as well as spider abundance in forest floor samples were highest in stands with medium diversity (DL 2) and lowest in pure beech stands (DL 1). The Shannon-Wiener index and spider numbers in pitfall traps decreased from DL 1 to DL 3, while the Shannon-Wiener index in forest floor samples increased in the opposite direction. Spider community composition differed more strongly between single plots than between diversity levels. Altogether, no general relationship between increasing tree species diversity and patterns of diversity and abundance in spider communities was found. It appears that there is a strong influence of single tree species dominating a forest stand and modifying structural habitat characteristics such as litter depth and herb cover which are important for ground-living spiders.     

古田山国家级自然保护区白颈长尾雉的分布格局及其季节变化

为了解浙江省古田山国家级自然保护区内白颈长尾雉(Syrmaticus ellioti)的分布格局和季节变化, 2014年5月至2016年4月, 我们对其进行了为期2年的网格化监测。共有44个公里网格拍摄到白颈长尾雉, 独立探测数量为211次, 雌雄性比为1 : 1.64。白颈长尾雉主要分布在实验区和缓冲区, 其探测率在常绿落叶阔叶混交林、杉木(Cunninghamia lanceolata)林、针阔叶混交林、人工油茶(Camellia oleifera)林和常绿阔叶林中依次递减, 主要分布在海拔600-800 m。冬、春两季, 白颈长尾雉活动强度和区域相对较小, 而夏、秋两季活动强度和区域相对增加, 其分布在海拔段(F_4,12 = 3.76, P < 0.05)和季节间(F_3,12 = 3.34, P < 0.05)都存在显著差异。对海拔和气候因子进行回归分析发现, 日平均气温和海拔对白颈长尾雉是否出现均有极显著影响(P < 0.01); 白颈长尾雉月探测率和探测到白颈长尾雉位点的海拔均与月平均气温呈极显著正相关(P < 0.001), 而与月平均降水量无显著线性关系(P > 0.05)。这表明白颈长尾雉的活动在很大程度上受海拔和气温影响, 随月平均气温的升高有向高海拔迁移的趋势。模型选择和多模型推断显示, 最优模型仅保留“100 m内水源”这一个变量, 次优模型是“100 m内水源 × 海拔”, 最优和次优模型的权重分别为0.18和0.14, “100 m内水源”和“海拔”是影响白颈长尾雉在保护区内分布的重要因子, 重要值分别为0.82和0.51。因此, 白颈长尾雉的分布并非仅由某一个或几个环境变量决定, 而是由多个环境变量共同决定。气温的变化和对不同海拔段的选择是导致白颈长尾雉形成不同季节分布格局的原因。