Herb Cover Research Articles

Which factors influence the density of birch (Betula pendula Roth) seeds in soil seed banks in temperate woodlands?

The natural regeneration of disturbed forest sites is becoming increasingly important due to climate change. Following disturbance events affecting large areas seed trees are often absent from the site, and regeneration solely by means of seed rain may not be successful. In these situations, soil seed banks are an important driver of the regeneration and reforestation of forest sites. The aim of the study was to determine the birch seed density in the soil of birch stands, spruce–birch stands and spruce stands dependent upon the number of seed trees (stands) and upon varying degrees of ground cover using the ‘seedling emergence method.’ The study revealed a significant link between the quantity of germinated birch seedlings in soil samples and the presence of seed sources. Seedling densities of birch in the different stand categories reached 2644–6414 seedlings per m2 [n m−2] in birch stands, 392–759 n m−2 in spruce–birch stands and 25–122 n m−2 in pure spruce stands. The density of germinated birch seedlings was also negatively affected by the soil layer. In all stand types, the factors humus thickness, litter cover, moss cover and herb cover had no significant influence on the amount of birch seedlings. Successful rapid regeneration of disturbed sites by means of the birch soil seed bank is guaranteed in cases where birch stands, or at least birch seed trees, were present before the event. The influence of ground cover on the regeneration potential of birch from the soil is negligible.

Agricultural intensification erodes taxonomic and functional diversity in Mediterranean olive groves by filtering out rare species

Abstract Agri‐Environmental Schemes (AES) have been proposed to mitigate the impact of agriculture on both taxonomic and functional biodiversity. However, a better knowledge of the mechanisms involved in the loss of agrobiodiversity is needed to implement efficient AES. An unbalanced effort on research towards arable lands compared to permanent crops, and on fauna relative to plants, is patent, which limits the generalization of AES effectiveness. We evaluated the effects of agricultural management and landscape simplification on taxonomic and functional diversity of the ground herb cover of 40 olive groves. We use a recently developed approach based on Hill numbers (rare, common and dominant species based) to analyse taxonomic and functional dissimilarity between farms with contrasting agricultural practices, and its potential attenuation by landscape complexity. We further explore the filtering effect of agricultural intensification on functional traits, and the relationship between functional and species richness across landscapes. We found that taxonomic and functional dissimilarity of herb assemblages between intensively and low‐intensively managed fields was mainly due to rare species. Dissimilarity decreased as landscape complexity increased, evidencing that complex landscapes attenuate the impact of agriculture intensification on herb assemblage composition. Agricultural intensification favoured more functionally homogeneous assemblages and disfavoured the herbs pollinated by insects, while it did not seem to affect wind‐pollinated species. Overall, functional richness increased exponentially with species richness across landscapes, but the latter was insufficient to drive any clear enhancement in functional richness in simple landscapes. In contrast, high species richness accelerated the enhancement in functional richness in intermediate and complex landscapes. These results highlight the functional filtering that intensive agriculture has generated for decades in homogeneous olive‐dominated landscapes. Synthesis and applications. Herb cover is essential to support the fauna of permanent croplands and their sustainable production. Hence, Agri‐Environmental Schemes (AES) in these croplands should promote management practices favouring the diversity and functionality of herb assemblages. Such AES should be particularly prioritized in homogeneous landscapes, where ground herb cover composition and function has long been homogenized to a great extent.

Assessing Forest Structural and Topographic Effects on Habitat Productivity for the Endangered Apennine Brown Bear

Any forest management potentially affects the availability and quality of resources for forest-dwelling wildlife populations, including endangered species. One such species is the Apennine brown bear, a small and unique population living in the central Apennines of Italy. The conservation of this relict bear population is hampered by the lack of knowledge of the fine-scale relationships between productivity of key foods and forest structure, as this prevents the design and implementation of effective forest management plans. To address this issue, we sampled the main structural stand attributes within the bear’s range and used multivariate generalized linear mixed models in a Bayesian framework to relate forest structural attributes to proxies of productivity of key bear foods. We found that hard mast was positively associated with both forest typology and high forest system, but negatively related to both the time elapsed since the last forest utilization and the amount of deadwood. The availability of soft-mast producing species was positively related to past forestry practices but negatively associated with steep slopes historically managed with high tree densities and a low silvicultural disturbance. Our findings also suggest that herb cover was negatively affected by terrain steepness and basal area, while herb productivity was positively affected by northern and southern exposure. Additionally, richness of forest ants was associated with forests characterized by low volume and high density. Our findings confirm that the productivity of natural bear foods is strongly affected by forest structural and topographical characteristics and are relevant as preliminary information for forest management practices to support the long-term conservation of Apennine bears.

What shapes ground beetle assemblages in a tree species-rich subtropical forest?

As woody plants provide much of the trophic basis for food webs in forests their species richness, but also stand age and numerous further variables such as vegetation structure, soil properties and elevation can shape assemblages of ground beetles (Coleoptera: Carabidae). However, the combined impact of these numerous variables on ground beetle diversity and community structure has rarely been studied simultaneously. Therefore, ground beetles were studied in 27 plots in a highly diverse and structurally heterogeneous subtropical forest ecosystem, the Gutianshan National Park (southeast China) using pitfall traps and flight interception traps. Both trapping methods collected partly overlapping species spectra. The arboreal fauna was dominated by lebiines and to a smaller extent by tiger beetles and platynines; the epigeic fauna comprised mostly representatives of the genus Carabus and numerous tribes, especially anisodactylines, pterostichines, and sphodrines. Ground beetle species richness, abundance, and biomass of the pitfall trap catches were analyzed with generalized linear mixed models (GLMMs), fitted with seven environmental variables. Four of these variables influenced the ground beetle assemblages: Canopy cover, herb cover, pH-value of the topsoil and elevation. Contrary to our expectations, woody plant species richness and stand age did not significantly affect ground beetle assemblages. Thus, ground beetles seem to respond differently to environmental variables than ants and spiders, two other predominantly predatory arthropod groups that were studied on the same plots in our study area and which showed distinct relationships with woody plant richness. Our results highlight the need to study a wider range of taxa to achieve a better understanding of how environmental changes affect species assemblages and their functioning in forest ecosystems.

Range-wide breeding habitat use of the critically endangered Yellow-breasted Bunting Emberiza aureola after population collapse.

The population of the Yellow‐breasted Bunting Emberiza aureola, a formerly widely distributed and abundant songbird of northern Eurasia, suffered a catastrophic decline and a strong range contraction between 1980 and 2013. There is evidence that the decline was driven by illegal trapping during migration, but potential contributions of other factors to the decline, such as land‐use change, have not yet been evaluated. Before the effects of land‐use change can be evaluated, a basic understanding of the ecological requirements of the species is needed. We therefore compared habitat use in ten remaining breeding regions across the range, from European Russia to Japan and the Russian Far East. We also assessed large‐scale variation in habitat parameters across the breeding range. We found large variation in habitat use, within and between populations. Differences were related to the cover and height of trees and shrubs at Yellow‐breasted Bunting territories. In many regions, Yellow‐breasted Buntings occupied early successional stages, including anthropogenic habitats characterized by mowing, grazing, or fire regimes. We found that the probability of presence can be best predicted with the cover of shrubs, herbs, and grasses. Highest probabilities were found at shrub cover values of 40%–70%. Differences in habitat use along a longitudinal gradient were small, but we found strong differences across latitudes, possibly related to habitat availability. We conclude that the remaining Yellow‐breasted Bunting populations are not limited to specific habitat types. Our results provide important baseline information to model the range‐wide distribution of this critically endangered species and to guide targeted conservation measures.

Illegal harvesting and livestock grazing threaten the endangered orchid Dactylorhiza hatagirea (D. Don) Soó in Nepalese Himalaya.

Harvesting of orchids for medicine and salep production is a traditional practice, and increasing market demand is spurring illegal harvest. Ethno‐ecological studies in combination with the effect of anthropogenic disturbance are lacking for orchids. We compared population density and structure, and tuber biomass of Dactylorhiza hatagirea (D. Don) Soó for three years in two sites: Manang, where harvesting of medicinal plants was locally regulated (protected), and Darchula, where harvesting was locally unregulated (unprotected). Six populations were studied along an elevation gradient by establishing 144 temporary plots (3 × 3 m2) from 3,400 to 4,600 m elevations. Mean density of D. hatagirea was significantly higher in the locally protected (1.31 ± 0.17 plants/m2) than in the unprotected (0.72 ± 0.06 plants/m2) site. The protected site showed stable population density with high reproductive fitness and tuber biomass over the three‐year period. A significant negative effect (p < .1) of relative radiation index (RRI) on the density of the adult vegetative stage and a positive effect of herb cover on juvenile and adult vegetative stages were found using mixed zero‐inflated Poisson (mixed ZIP) models. The densities of different life stages were highly sensitive to harvesting and livestock grazing. Significant interactions between site and harvesting and grazing indicated particularly strong negative effects of these disturbances on densities of juvenile and adult reproductive stages in the unprotected site. Semi‐structured interviews were conducted with informants (n = 186) in the villages and at the ecological survey sites. Our interview results showed that at the protected site people are aware of the conservation status and maintain sustainable populations, whereas the opposite was the case at the unprotected site where the populations are threatened. Sustainability of D. hatagirea populations, therefore, largely depends on controlling illegal and premature harvesting and unregulated livestock grazing, thus indicating the need for permanent monitoring of the species.

Forest plant and macrofungal differences in the Greater and Lesser Khingan Mountains in Northeast China: A regional-historical comparison and its implications

Forests in Northeast China in the Greater and Lesser Khingan Mountains (GKM and LKM) account for nearly 1/3 of the total state-owned forests in the country. Regional and historical comparisons of forest plants and macrofungi will favor biological conservation, forest management and economic development. A total of 1067 sampling plots were surveyed on forest composition and structure, with a macrofungi survey at Liangshui and Huzhong Nature Reserves in the center of two regions. Regional and historical differences of these parameters were analyzed with a redundancy ordination of their complex associations. There were 61–76 families, 189–196 genera, and 369–384 species, which was only 1/3 of the historical records. The same dominant species were larch and birch with Korean pine (a climax species) less as expected from past surveys in the LKM. Shrub and herb species were different in the two regions, as expected from historical records. There was 10–50% lower species diversity (except for herb evenness), but 1.8- to 4-time higher macrofungi diversity in the GKM. Compared with the LKM, both tree heights and macrofungi density were higher. Nevertheless, current heights averaging 10 m are half of historical records (> 20 m in the 1960s). Edible macrofungi were the highest proportion in both regions, about twice that of other fungal groups, having important roles in the local economy. A major factor explaining plant diversity variations in both regions was herb cover, followed by shrubs in the GKM and herb-dominant species in the LKM. Factors responsible for macrofungi variations were tree density and shrub height. Vaccinium vitis-idaea and Larix gmelinii in the GKM but tree size and diversity were important factors in the LKM. Our findings highlighted large spatial and historical differences between the GKM and LKM in plant-macrofungal composition, forest structure, and their complex associations, which will favor precise conservation and management of forest resources in two region in the future.

Influence of Abiotic and Biotic Factors on Soil Microbial Biomass in Robinia pseudoacacia Plantations in the Loess Hilly Region

The ecological productivity of the Robinia pseudoacacia L. (RP) widely cultivated on the Loess hilly region has been widely questioned with its aging. Soil microbial biomass (SMB) plays a key role in soil nutrient dynamics and productivity of the ecosystems. Understanding the main ecological drivers of SMB is supposed to be of importance for ecosystem functioning of RP in the Loess hilly region. In this study, we identified the most influential factors affecting SMB at 2 layers (0–10 cm and 10–30 cm) using forward selection in terms of plant characteristics (forest age, tree height, diameter at breast height, tree canopy, crown base height, herb height, herb number, herb coverage, herb ground diameter and herb diversity), soil physiochemical characteristics (soil bulk density, pH, water content, soil organ carbon, soil total and available nutrient content) and topographical properties (elevation, aspect and slope). We also analyzed individual and interactive effects (plant–soil, plant–topography, soil–topography, plant–soil–topography) using general linear model (GLM) analysis. Among all plant variables, tree canopy and understory richness had the greatest impact on SMB. The soil variables with the greatest impact on SMB were bulk density and available phosphorus. Elevation was the most important topographic factor affecting SMB. When we considered the interactive effects among plant, soil physicochemical and topographical variables on SMB, a significant interaction effect occurred at a depth of 10–30 cm soil layer. We concluded that individual effects of abiotic and biotic factors significantly affect SMB at 0–10 cm, while the interaction of these factors mainly played roles at 10–30 cm. These results provide a basis for maintaining soil health and productivity using efficient SMB by providing suitable abiotic and biotic habitats.

Spontaneous succession on road verges—An effective approach with minimum effort

AbstractRoad verges represent new habitats providing an opportunity for enhancing biodiversity in human‐altered landscapes. However, it is common practice to plant trees or sow species‐poor seed mixtures regardless of their geographical origin. We assessed the effectiveness of spontaneous restoration to fulfil the requirements for both functions, the formation of vegetation cover to prevent erosion and native species‐rich vegetation, which may provide conservation benefits. We sampled 113 vegetation plots on road verges in the Czech Republic, central Europe. The sampling plots were 25 m2 in size and differed in age (1–42 years). We recorded surrounding landscape (land‐cover categories, landscape heterogeneity, and length of roads and railways in a 1‐km radius zone) and site factors (altitude, substrate texture, slope, aspect, and potential solar radiation) and analysed the data using multivariate methods. Species composition was significantly explained by successional age, altitude, substrate texture, and surrounding forest area. The total herb cover reached on average 30% already in the first 2 years, and later shrub and tree layers developed. Out of 320 identified vascular plant species, almost 5% (15 species) were endangered and 6% (19 species) were invasive aliens. Early successional stages were characterised by a high cover of insect‐pollinated species, which can serve as important food sources for insects. Despite some limitations (poor seed sources and inconvenient site conditions), our results showed that spontaneous succession could be used more often in the restoration of road verges because this approach may provide an alternative, cost‐effective solution of reasonable conservation value.

INFLUENCE OF SINGLE TREES ON FLORISTIC DIVERSITY OF STEPPE MEADOWS AND POPULATION STRUCTURE OF SOME RARE PLANT SPECIES

In the zone of broad-leaved forests of the European Russia, steppe meadows have been preserved showing rich floristic composition and making a significant contribution to the biological diversity of the territories. Bryansk oblast is one of the forest regions in Russia where such meadows are found. Here, steppe meadows with high floristic diversity and a large number of rare plant species have survived. Trees from surrounding forest areas are constantly encroaching on these meadows. Most of the young trees die from regular grass fires and economic activity. However, some individuals survive and reach a generative state, becoming relatively resistant to ground fires. The influence of single trees on the floristic diversity of steppe meadows was studied at two levels of living system organization – coenotic and population levels. Polydominant steppe meadows and polydominant steppe meadows with single generative trees were studied at the coenotic level; and coenopopulations of Iris aphylla, Anemone sylvestris, and Anthericum ramosum were studied at the population level. Collecting the material, we used different methods: geobotanical, demographic, and measurements of environmental factors (illumination, slope steepness, and the frequency of grass fires). Polydominant steppe meadows were found to be were preserved in the middle part of steep slopes unsuitable for haymaking and grazing and subjected to infrequent grass fires. These communities have high floristic diversity and stable coenopopulations of model species. Ontogenetic spectra of Anemone sylvestris, Anthericum ramosum, and Iris aphylla are of the complete left-hand type with the maximum number of individuals. Single trees (Quercus robur, Tilia cordata) have controversial influence on the vegetation of polydominant steppe meadows. On the one hand, with the introduction of trees, species diversity of communities increases. This is due to the fact that trees offer resting places and shelter for birds that spread plant diaspores. On the other hand, mature trees shade the herb cover. This leads to cover reduction and occurrence of steppe and dry meadow species, as well as affects their population structure. The ontogenetic spectrum of Anemone sylvestris is still complete, whereas that of Iris aphylla becomes incomplete, and the spectrum of Anthericum ramosum becomes unfinished.

Surface temperature and shrub cover drive ground beetle (Coleoptera: Carabidae) assemblages in short‐rotation coppices

Increasing demand for biomass has led to an on‐going intensification of fuel wood plantations with possible negative effects on open land biodiversity. Hence, ecologists increasingly call for measures that reduce those negative effects on associated biodiversity. However, our knowledge about the efficiency of such measures remains scarce. We investigated the effects of gap implementation in short rotation coppices (SRCs) on carabid diversity and assemblage composition over 3 years, with pitfall traps in gaps, edges and interiors. In parallel, we quantified soil surface temperature, shrub‐ and herb cover. Edges had the highest number of species and abundances per trap, whereas rarefied species richness was significantly lower in short rotation coppice interiors than in other habitat types. Carabid community composition differed significantly between habitat types. The main environmental drivers were temperature for number of species and abundance and shrub cover for rarefied species richness. We found significantly higher rarefied species richness in gaps compared with interiors. Hence, we argue that gap implementation benefits overall diversity in short rotation coppices. Furthermore, the differences in species community composition between habitat types through increased species turnover support carabid diversity in short rotation coppices. These positive effects were largely attributed to microclimate conditions. However, to maintain positive effects, continuous management of herb layer might be necessary.

Ecological Vulnerability Evaluation Model of Sichuan-Tibet Railway Based on Fuzzy Matter-element Analysis

In order to identify the ecological conditions of Sichuan-Tibet Railway, based on the vulnerability evaluation framework of “exposure-sensitivity-adaptation”, this paper selects 20 evaluation indexes including temperature, precipitation, snowfall, herb coverage, total number of plant species, population density and per capita GDP, and establishes a multi-element and multi-attribute comprehensive evaluation system. The comprehensive evaluation system is divided into eight basic judgment indexes, and the weight is determined based on the fuzzy matter-element analysis method. The basic judgment index scores are obtained through cluster analysis, and the ecological vulnerability evaluation model is established. It is expected to provide theoretical reference for the construction of Sichuan-Tibet Railway in ecologically fragile areas to protect and improve the ecological environment.

Living fences decrease the edge effect on nest predation in a tropical dry forest landscape: evidence from an experiment using artificial nests

Agricultural expansion has contributed to the loss and fragmentation of natural habitats and, as a consequence, the edge effect in these habitats has increased, leading to nest predation rates higher at the edge of fragments than in the interior. Living fences in abandoned croplands, however, add a structural component to the landscape which can help to mitigate the effects of disturbance. We used artificial nests to assess whether a living fence at the edge of a fragment of tropical dry forest, immersed in an agricultural landscape, can assuage the edge effect by decreasing predation rates. We identified the predators that attacked nests at several distances from the living fence and related the frequency of predator attacks with plant height, leaf height diversity, and tree and herb coverage. Vegetation structure of the living fence was vertically more complex than that found inside the fragment. 52% of nests were predated and we did not find a significant relationship between predation rates and the proximity of nests to the living fence, suggesting a null edge effect on predation. Birds were the most frequent predators, followed by rodents and carnivorous mammals, with the composition of predators varying among transects. The composition of predators and vegetation structure of the living fence were the factors that explained the null edge effect on nests predation. Our results indicate that the presence of a living fence at the edge of a fragment in agroforestry systems could mitigate the edge effects on nest predation.

Seeds and seedlings of oaks suffer from mammals and molluscs close to phylogenetically isolated, old adults.

Mammals and molluscs (MaM) are abundant herbivores of tree seeds and seedlings, but how the trees and their environment affect MaM herbivory has been little studied. MaM tend to move much larger distances during the feeding stage than the more frequently studied insect herbivores. We hypothesize that MaM (1) select and stay within the patches that promise to be relatively the richest in seeds and seedlings, i.e. patches around adult trees that are old and within a distantly related, less productive neighborhood; and (2) try to remain sheltered from predators while foraging, i.e. mammals remain close to adult trees or to cover by herbs while foraging, and might force their mollusc prey to show the opposite distribution. We exposed oak acorns and seedlings in a temperate forest along transects from adult conspecifics in different neighbourhoods. We followed acorn removal and leaf herbivory. We used exclusion experiments to separate acorn removal by ungulates vs. rodents and leaf herbivory by insects vs. molluscs. We measured the size of the closest conspecific adult tree, its phylogenetic isolation from the neighbourhood and the herbaceous ground cover. Consistent with our hypothesis, rodents removed seeds around adult trees surrounded by phylogenetically distant trees and by a dense herb cover. Molluscs grazed seedlings surrounding large conspecific adults and where herb cover is scarce. Contrary to our hypothesis, the impact of MaM did not change from 1 to 5 m distance from adult trees. We suggest that foraging decisions of MaM repulse seedlings from old adults, and mediate the negative effects of herbaceous vegetation on tree recruitment. Also, an increase in mammalian seed predation might prevent trees from establishing in the niches of phylogenetically distantly related species, contrary to what is known from insect enemies.

A non-native woody plant compromises conservation benefits of mid-field woodlots for birds in farmland

Agricultural intensification seriously threatens European biodiversity. To mitigate this threat, farmland habitat suitability should be improved. Mid-field woodlots surrounded by intensively cultivated fields or grasslands, represent one of the promising tools for such improvement. However, woodlots can be dominated by non-native plants and their impacts on woodlot function as refugees for biodiversity remains unclear. Therefore, we studied the impact of the invasive black locust (Robinia pseudoacacia L.) on bird species richness in woodlots in intensively cultivated Central European farmland. We surveyed 27 mid-field woodlots (13 covered by native vegetation and 14 dominated by black locust) in the Czech Republic, relating the species richness of all birds, habitat specialists and habitat generalists to woodlot characteristics: black locust occurrence, distance to the main forest, age of the woodlot, vegetation structure, arthropod biomass (representing food supply for birds), surrounding habitats and type of crops in which they are embedded. Our results suggest that the woodlots covered by the black locust had lower species richness of all birds, habitat specialists and habitat generalists than the woodlots covered by native tree species. The negative impact of the invasive woody plant on birds was likely driven by changes in vegetation structure since such woodlots had lower coverage of the shrub layer and less continuous canopy. This mechanism was particularly supported in habitat generalists, whereas habitat specialists additionally showed positive relationships to the other vegetation characteristics (namely the coverage of herbs in the ground layer and the proportion of medium-sized trees). Our study shows that even though mid-field woodlots host numerous bird species, their role in the delivery of conservation benefits for breeding birds is compromised if non-native woody plants dominate the vegetation. Therefore, from the perspective of breeding birds’ conservation, the native woody plant species should be used for woodlot establishment.

Tree Change in Nemoral Spruce Forests of the Central Forest Reserve

The paper discusses changes in forest-forming species in the nemoral spruce forests of the Central Forest Reserve (Tver Region, the Russian Federation). A comparison is made of the characterization of vegetation in the reserve spruce forests, carried out during the first survey of the reserve by Ya. Ya. Alekseev in 1931 (Alekseev, 1935) with the descriptions of vegetation made by the author from 2011 to 2019. It is shown that the coverage of nemoral herbs in the spruce forests of the reserve has increased over the past 90 years. In addition, three types of broadleaf trees (Tilia cordata Mill., Acer platanoides L. and Ulmus scabra Mill.) have greatly increased their abundance in the stand, most notably the linden. In recent decades, the decay of nemoral spruce forests has been taking place in the Central Forest Reserve. The birch-aspenspruce stand is not replenished with spruce renewal but is replaced by linden-maple forests. The vitality of spruce undergrowth is deteriorating. After the decay of a spruce forest, a change of the tree dominants occurs on 74% of the trial plots and the stand continues with a spruce forest on 26%. The largest part of the reserve's nemoral spruce forests arose after major disturbances 100–150 years ago (on the site of burned-out areas, hurricane windblows and cuttings). Old nemoral spruce forests were formed during the period when severe frosts prevented linden and maple from entering the stand. Currently, the coincidence of climate warming with the aging of the spruce stand and the removal of anthropogenic influence contributed to the release of maple and linden from the undergrowth into the stand and change to a spruce-deciduous forest. Under the prevailing climatic conditions, a return to the spruce forest is possible in the event of a burning out or when the climate becomes cold. The nemoral spruce forest is an ecotone type and, depending on conditions, becomes a spruce or broad-leaved forest.

Spatial Utilization and Microhabitat Selection of the Snow Leopard (Panthera uncia) under Different Livestock Grazing Intensities

AbstractThere is increasing conflict between snow leopards and humans in many protected areas, the main driver of which is the overlap in spatial utilization between snow leopards and livestock. Understanding the spatial utilization and microhabitat selection of snow leopards in areas featuring different levels of livestock grazing is important to better understand and resolve this conflict, but such studies are rare. Here, we conducted line transect and plot surveys in low- and high-grazing-disturbance areas (LGDAs and HGDAs) in Wolong National Reserve, southwestern China. We compared snow leopard spatial utilization and microhabitat characteristics between LGDAs and HGDAs. Results showed that snow leopards had aggregated distribution in both LGDAs and HGDAs, but the distribution of snow leopards in HGDAs was more centralized than in LGDAs. Herb cover and height in LGDAs were greater than in HGDAs. We fit a resource selection function (RSF) that showed that snow leopards preferentially selected higher elevation, smaller basal diameter of shrubs, and lower height of herbs in LGDAs. In contrast, there were no significant microhabitat factors in our snow leopard RSF in HGDAs. Our results indicate that high-intensity grazing tends to reduce the habitat types available to and preferential selectivity of habitat by snow leopards. We recommend that livestock grazing should be controlled to restore the diversity of the alpine ecosystems in Wolong Nature Reserve. Our findings also highlight the need for evaluating the impact of livestock grazing on rare animals in alpine environments (e.g., snow leopard) in other areas facing similar issues.

青海东部人工生态公益林近自然经营的林分结构调整

依据研究区5种典型人工林近自然状况，以人工生态公益林的近自然经营管理为目标，提出林分结构调整策略与方法。主要从林分结构、物种组成、年龄及枯死木几个方面考虑选取了垂直结构、水平结构、草本盖度及其多样性、天然更新、物种多样性、组成系数、直径分布、枯木比例、健康木比例10个指标，应用基于单位圆的π值法则，采取定性与定量相结合的方法，对5种林分的近自然状态做出评价并依据评价结果提出相应改造措施。青海云杉-白桦混交林（ω_PB=0.4786）属于远近自然林分，此类林分在密度合理的情况下无需过多人为抚育；青杨-白桦混交林（ω_BP=0.2664）属于近人工林，此类林分以伐除病虫害严重的青杨、调整密度和补植青海云杉为主；青海云杉-青杨混交林（ω_PP=0.2283）属于近人工林，此类林分以伐除病虫害严重的青杨、调整密度和补植白桦为主；青海云杉-落叶松混交林（ω_PL=0.1872）属于人工林，此类林分以调整密度和补植白桦为主；青海云杉纯林（ω_P=0.0190）属于人工林，此类林分以调整密度和营造杉桦混交林为主。通过近自然度评价与分析，为当地近自然经营提供了直观可靠的依据。在进行林分结构调整时，首先通过伐除干扰木来调整林分密度，其次要营造针阔混交林分，其中以青海云杉和白桦混交林为主要目标林分。;At present, although large-scale forest land has been restored and exploited in China through a large number of artificial afforestation, the tree species of the plantation are simple and the structure law,it has caused many ecosystem problems such as pests and diseases, soil fertility decline, etc. Therefore, ensuring the sustainable development of forests through near-natural management is of great significance. Near-natural forest stands can effectively resist natural disasters and pests, optimize soil physical and chemical properties, increase biodiversity, and improve the ecological and economic benefits of forests. Through the evaluation of near-naturalness, we can understand the actual growth status of the stand and construct a near-natural evaluation system that conforms to the conditions of the local site conditions, thus providing a reliable basis for near-natural management. According to the natural conditions of five typical plantation forests in the eastern part of Qinghai province, this paper aims at the near-natural management of plantation ecological public forests and tries to put forward the stand structure adjustment strategies and methods. The vertical structure, horizontal structure, herb coverage and its diversity, natural regeneration, species diversity, composition coefficient, diameter distribution, ratio of dead wood, and healthy wood are mainly selected from the aspects of stand structure, species composition, age and dead wood. Based on the combination of qualitative description and quantitative analysis, the near-natural unit circle π-value rule was applied to evaluate the natural characteristics of five typical forest stands and propose corresponding reform measures based on the evaluation results. Picea crassifolia-Betula platyphylla mixed forest (ω_PB=0.4786) is a far from nature forest. Such forests do not need too much artificial rearing under reasonable density. Populus cathayana-Betula platyphylla mixed forest (ω_BP=0.2664) is near plantation forest. In this kind of stand, the main activities are to cut down the Populus cathayana infested with insect pests, adjust the density and replant Picea crassifolia. Picea crassifolia-Populus cathayana mixed forest (ω_PP=0.2283) is near plantation forest. This kind of stand is mainly to cut off the Populus cathayana with serious disease and insect pest, adjust the density, and replant Betula platyphylla. Picea crassifolia-Larix principis-rupprechtii mixed forest (ω_PL=0.1872) is plantation forest. This type of stand is mainly to adjust density and replant Betula platyphylla. Picea crassifolia forest (ω_P=0.0190) is plantation forest. This type of stand is mainly for adjusting density and constructing Picea crassifolia-Betula platyphylla mixed forests. Through the evaluation and analysis of the near-natural condition, it provides a direct and reliable basis for local near-natural management. The method to adjust the stand structure is to first adjust the stand density by removing disturbing trees, and then create a mixed forest of coniferous and broad-leaved trees, among which Picea crassifolia-Betula platyphylla mixed forest is the main one.

Co-Variation among Vegetation Structural Layers in Forested Wetlands

Co-variation among vegetation structural layers occurs in some forests but has been minimally found in forested wetlands. We assessed co-variation in six vegetation layers (three size classes of trees, tree seedlings, shrubs, and herbs) in 39 forested wetlands including in five before and after invasion by the beetle emerald ash borer (Agrilus planipennis; EAB) in northwestern Ohio, USA. Across the 39 wetlands, cover of wetland herbs requiring full sunlight was negatively related to tree density, while herbs tolerant of shade minimally co-varied with tree layers. Several wetlands contained both large trees and regeneration (small trees and seedlings) of the same tree species, but often distributions of large trees and regeneration were disjointed. Variation in plant community quality (e.g., non-native cover, floristic quality) for understory layers was partly modeled (34–75% of variance) using multivariate combinations of tree layers. Low-density pin oak (Quercus palustris) flatwoods, which contained species-rich, high-quality understories, drove much co-variation in vegetation layers, suggesting that coupling of layers might occur on only segments of landscape gradients. Another factor was that nearly every site had a different dominant herbaceous species, producing extreme compositional heterogeneity (94% dissimilarity among plots), limiting possible co-variation, but creating high beta diversity. On the five long-term EAB sites, shrub and herb composition co-varied before EAB invasion, but not 14 years later after shrub cover doubled. High diversity in vegetation layers among sites suggests that conserving forested wetlands, including sites that individually might not have high floristic quality, can be a major contributor to landscape diversity.

Rodent assemblage composition as indicator of fire severity in a protected area of south‐central Chile

AbstractFires have a considerable impact on biological communities and ecosystems, within which the assessment of burned habitats requires consideration of indicator species or assemblages useful for monitoring. The short‐term effects of fires can be easily deduced from analysing assemblages of animals with short generation times and high fertility rates, such as rodents. Here, we evaluated the effect of fire severity in a protected area of southern Chile on abundance, composition and diversity of rodent assemblages. We sampled rodents and vegetation variables during summer and fall over two years (2017 and 2018) in forest stands with different levels of fire severity (high, low and unburned stands). Changes in diversity and abundance were found between unburned and burned stands, with these differences being more noticeable during the fall of the first year. Abundances of rodent species exhibited marked fluctuations over the study period, but two species consistently decreased their abundances as fire severity increased, and with the absence of one species in burned stands. The adverse fire effects were less evident during the second year due to the overall low capture rates (1.3–1.9%). Rodent species were differently affected by fire, with Irenomys tarsalis (arboreal rat) being the species most sensitive to fires. The effect of fire severity on abundance of rodent species was associated with changes in the vegetation variables, where dead wood, canopy and herb cover showed a low correlation (R = 0.147). Our results suggest that fires of high severity cause important disturbances on habitat and food resources that result in short‐term effects on the rodent assemblage. Fires apparently act as an ecological filter for the more specialised species while offering an opportunity for the settlement of generalist species. Hence, the monitoring of rodent species differing in their ecological traits, such as food habits and space use, offers an opportunity for assessing the short‐term recovery patterns of wildlife after fire disturbances.