Mountain Shrublands Research Articles

Soil functional indicators in a semi-arid environment change patchy under the influence of shrub species

The presence of mountain shrublands within semi-arid regions is of great importance due to their function in the preservation of water and soil resources and their contribution to the conservation of biodiversity. The study of the effects of semi-arid highland shrubs on soil functional indicators has not yet received sufficient attention. To fill this knowledge gap, we conducted a study to investigate the effects of different shrub species specifically Carpinus orientalis Miller, Berberis integerrima Bunge, Crataegus microphylla C. Koch, Prunus spinosa L., and Rhamnus pallasii Fisch. and C. A. Mey) on soil physical, chemical, and biological properties. For this study, 15 individuals of each of the above-mentioned shrub species were selected. Soil samples were collected at a depth of 10 cm and an area of 30 cm × 30 cm beneath the canopy of these particular species. The examination of the influence of various independent factors on the variability of soil microclimate and biological characteristics indicates that the presence of shrub covers is the primary determinant of changes in water content, fauna and microflora population, microbial respiration and biomass, whereas soil temperature, MBN/MBP and qCO2 are more affected by season factor. Based on the biological fertility index, all the studied shrub covers are in the medium class with the maximum score under Carpinus shrub. Results indicate that soil biological characteristics play a more significant role in distinguishing in terms of soil functional indicators. Based on hot spots output, the soil functional indicators decreased in order of Carpinus > Crataegus > Berberis > Prunus > Rhamnus. As a conclsuion, Carpinus create hot spots (areas) of soil functional indicators in the mountainous ecosystems that claimed the potentially role of nutrient-rich soil cycles.

Optimizing Drone-Based Surface Models for Prescribed Fire Monitoring

Prescribed burning and pyric herbivory play pivotal roles in mitigating wildfire risks, underscoring the imperative of consistent biomass monitoring for assessing fuel load reductions. Drone-derived surface models promise uninterrupted biomass surveillance but require complex photogrammetric processing. In a Mediterranean mountain shrubland burning experiment, we refined a Structure from Motion (SfM) and Multi-View Stereopsis (MVS) workflow to diminish biases in 3D modeling and RGB drone imagery-based surface reconstructions. Given the multitude of SfM-MVS processing alternatives, stringent quality oversight becomes paramount. We executed the following steps: (i) calculated Root Mean Square Error (RMSE) between Global Navigation Satellite System (GNSS) checkpoints to assess SfM sparse cloud optimization during georeferencing; (ii) evaluated elevation accuracy by comparing the Mean Absolute Error (MAE) of six surface and thirty terrain clouds against GNSS readings and known box dimensions; and (iii) complemented a dense cloud quality assessment with density metrics. Balancing overall accuracy and density, we selected surface and terrain cloud versions for high-resolution (2 cm pixel size) and accurate (DSM, MAE = 57 mm; DTM, MAE = 48 mm) Digital Elevation Model (DEM) generation. These DEMs, along with exceptional height and volume models (height, MAE = 12 mm; volume, MAE = 909.20 cm3) segmented by reference box true surface area, substantially contribute to burn impact assessment and vegetation monitoring in fire management systems.

The effect of different canopy composition of shrublands on soil quality indicators in a semi-arid climate of Iran

Mountain shrublands in semi-arid regions have a prominent role in regulating ecosystem services. Crataegus is a shrub distributed in wide areas of mountain semi-arid zones of the world. However, the effect of shrublands on soil quality indicators, especially fertility and biological activities, is poorly studied. In this study, the effect of various land covers with Crataegus melanocarpa M. B. (CM), Berberis integerrima Bunge. (BI), Ribes Uva – crispa L. (RU) and Prunus spinosa L. (PS) on soil quality indicators in Kinj region of northern Iran were investigated: 1) CM-BI-RU-PS; 2) CM-BI-RU; 3) CM-BI, and 4) pure CM. Soil samples were taken from 0 to 10 cm depth from each land cover as well as organic material (litter) and root samples. All samples were subjected to physical, chemical and biological analysis for soils and chemical analysis for litter and roots. The results showed that litter thickness under pure Crataegus (6.31 cm) was 4–53% higher than in mixed (2.95–6.05 cm) land covers. The soil fertility and biological characteristics were also lower by about 50% under the pure Crataegus than in the mixed shrublands. Based on principle component analysis (PCA), different land covers can be distinguished from each other based on litter, soil and root characteristics. In this regard, the first and second axes explained 36.86 and 16.40% of the total variance, respectively. PCA output showed that habitats with higher litter quality (i.e., higher values of N), and high soil fertility and biological activity belonged to CM-BI-RU-PS and CM-BI-RU land covers. Conversely, CM-BI and pure CM covers have poorer litter quality (i.e., higher values of C and C/N ratio) and lower levels of soil fertility indicators and biological activities. The results of this research indicate that the diversity of land cover in Crataegus ecosystems in semi-arid areas can maintain soil quality and create hotspots of soil quality indicators. Based on this, it is recommended to pay more attention to species diversity in order to restore degraded habitats in similar ecosystems, thus is important planting companion shrub species in addition to Crataegus.

Soil biological quality as affected by vegetation types in shrublands of a semi-arid montane environment

Mountain shrublands in semi-arid zones have a relevant effect in protecting water and soil, and conserving biodiversity. Nutrient availability in vegetation layers of semi-arid shrublands, may increase biomass production and litter accumulation rates that may affect the soil nutrient cycle through the positive feedback. However, the effect of semi-arid mountainous shrublands on litter quality and soil properties is poorly studied. To fill these gaps, we studied different vegetation types (i.e., Ulmus carpinifolia Gled., Berberis integerrima Bunge, Malus orientalis Ugl., Pistacia atlantica Desf., Amygdalus lycioides Spach., Rhus coriaria L., Cotoneaster kotschyi Klotz. and Juniperus excelsa M. Bieb.), to assess litter quality, soil properties, and C and N mineralization in Iran. Totally, 240 litter or organic horizon and topsoil (0–10 cm depth) samples were taken under the studied vegetation types. Based on analysis of variance and Tukey test, soil fauna (earthworms, acarina, collembola, nematode, protozoa), microflora (bacteria and fungi), microbial (basal and substrate-induced respirations, microbial biomass) and enzyme (urease, acid phosphatase, arylsulfatase and invertase) properties, as well as C and N mineralization were highest under deciduous species, especially U. carpinifolia vegetation type. Conversely, J. excelsa, as an evergreen species, decreased soil quality bio-indicators by decreasing litter quality and soil fertility in the high mountain vulnerable semi-arid sites. Based of heat plots of principal component analysis, soil biological and biochemical properties, especially enzyme indicators, created hot spots of soil quality under the studied vegetation types. As a conclusion, deciduous species are the hotspot's bioindicator in the mountainous ecosystems, indicating their potential role in enriching soil nutrient cycles.

Effects of Precipitation Variation on Annual and Winter Soil Respiration in a Semiarid Mountain Shrubland in Northern China

In response to global climate change, future precipitation changes are expected to profoundly influence soil respiration in arid and semiarid areas. However, few studies focus on CO2 emissions from soils undergoing precipitation changes in semiarid mountain shrublands in winter. A precipitation-manipulation experiment with three levels of precipitation (30% decreased precipitation (DP), ambient precipitation (AP), and 30% increased precipitation (IP)) was performed to examine the effects of variable precipitation on soil respiration (SR) and wintertime contributions to annual SR emissions in Vitex negundo var. heterophylla shrub ecosystems located on the Middle Taihang Mountain in Hebei Province, northern China. The results showed that the average annual SR rates and winter SR rates ranged from 1.37 to 1.67 μmol m−2 s−1 and 0.42 to 0.59 μmol m−2 s−1 among the different precipitation treatments. The model based on soil moisture better represented the soil-respiration rates, suggesting that the variable precipitation extended the water’s limitation of the soil’s CO2 emissions. The cumulative annual soil CO2 emissions were 523, 578, and 634 g C m−2 in response to the DP, AP, and IP treatments, respectively. The ratio of the soil CO2 emissions in winter to the annual CO2 emissions varied from 7.6 to 8.8% in response to the different precipitation treatments. Therefore, ignoring the soil CO2 emissions in winter leads to the underestimation of the carbon losses in semiarid shrublands. Our results highlight that variable precipitation significantly influences soil-respiration rates, and soil CO2 emissions in winter must not be ignored when predicting the future feedback between SR and climate change in semiarid regions.

A Study of Two High Intensity Fires across Corsican Shrubland

This paper reports two experimental fires conducted at field-scale in Corsica, across a particular mountain shrubland. The orientation of the experimental plots was chosen in such a way that the wind was aligned along the main slope direction in order to obtain a high intensity fire. The first objective was to study the high intensity fire behavior by evaluating the propagation conditions related to its speed and intensity, as well as the geometry of the fire front and its impact on different targets. Therefore, an experimental protocol was designed to determine the properties of the fire spread using UAV cameras and its impact using heat flux gauges. Another objective was to study these experiments numerically using a fully physical fire model, namely FireStar3D. Numerical results concerning the fire dynamics, particularly the ROS, were also compared to other predictions of the FireStar2D model. The comparison with experimental measurements showed the robustness of the 3D approach with a maximum difference of 5.2% for the head fire ROS. The fire intensities obtained revealed that these experiments are representative of high intensity fires, which are very difficult to control in the case of real wildfires. Other parameters investigated numerically (flame geometry and heat fluxes) were also in fairly good agreement with the experimental measurements and confirm the capacity of FireStar3D to predict surface fires of high intensity.

Spatio-temporal differences in pollinator species richness, abundance and conservation status in a Mediterranean island

Although the Mediterranean basin is a hotspot of pollinator diversity, little is still known about how such diversity is distributed in the region and about its conservation status. This study contributes to filling this information gap by studying pollinator diversity parameters in one of the main Mediterranean islands, Mallorca, and further evaluating their conservation category according to the IUCN criteria. We focus on three communities, two coastal and one mountain shrubland, which we have studied for several years. For each community, we obtained the following variables: (1) Shannon diversity (H'), (2) Pielou's index (J'), (3) Number of pollinators per plant (Lp), (4) Flower visitation rate (FVR), (5) Specialisation index (d') and (6) Normalised degree of pollinators, i.e. the number of plants visited per pollinator species relative to the total number of plant species in the community (ND). All pollinators were categorised into functional groups to test for differences in such variables among them. Differences across communities, years and functional groups were tested through GLMMs. The three communities showed differences in pollinator species composition, species richness and diversity. Pollinator diversity also varied with time, especially in the coastal community, which suffered a major disturbance during one of the study years. Regardless of the functional group, the pollinator specialisation degree seems context-dependent. Native and endemic species might disappear in the short term if appropriate management measures are not taken to narrow down the threats to pollinator populations. Further research is urgently needed to assess most insect pollinators' conservation status in the Mediterranean before such rich diversity is lost forever.

New data on the status and ecology of a galliform at risk of extinction: the Pyrenean grey partridge (Perdix perdix hispaniensis) in the Iberian System (Soria, Spain)

A study was conducted in 2008–2010 to gain knowledge on the status and ecology of the endangered subspecies of grey partridge (Perdix perdix hispaniensis), at its southernmost range edge. From an historic breeding range of 28,300 ha, 15 different coveys (adults with juveniles) were observed in an area comprising 5,550 ha, with an estimated minimum autumn population size of 103–113 birds and a maximum of 163–181 birds. Spring pair density was estimated at 2.3 pairs/1,000 ha, and when considering only coveys, 6.8 partridges/1,000 ha. The majority of birds were located at an altitude above 1,690 m a.s.l., mainly in mountain shrubland (especially Calluna vulgaris and Erica spp.). Habitat loss was the most important threat for the species’ conservation. In conclusion, efforts should prioritize urgent habitat recovery and monitoring in order to change the fate of the species.

New data on the status and ecology of a galliform at risk of extinction: the Pyrenean grey partridge (Perdix perdix hispaniensis) in the Iberian System (Soria, Spain)

A study was conducted in 2008–2010 to gain knowledge on the status and ecology of the endangered subspecies of grey partridge (Perdix perdix hispaniensis), at its southernmost range edge. From an historic breeding range of 28,300 ha, 15 different coveys (adults with juveniles) were observed in an area comprising 5,550 ha, with an estimated minimum autumn population size of 103–113 birds and a maximum of 163–181 birds. Spring pair density was estimated at 2.3 pairs/1,000 ha, and when considering only coveys, 6.8 partridges/1,000 ha. The majority of birds were located at an altitude above 1,690 m a.s.l., mainly in mountain shrubland (especially Calluna vulgaris and Erica spp.). Habitat loss was the most important threat for the species’ conservation. In conclusion, efforts should prioritize urgent habitat recovery and monitoring in order to change the fate of the species.

Modern pollen representation of the vegetation of the Tagus Basin (central Iberian Peninsula)

The study of modern vegetation–pollen relationships has long been recognized as crucial for the proper interpretation of fossil pollen records. Despite the quickly growing number of palynological studies from central Iberia and its adjacent Atlantic margin, comprehensive studies about modern pollen representation at broad spatial scales were still lacking. In this paper, we have studied the vegetation–pollen relationships in the Tagus Basin in 62 sites located along a wide environmental gradient from Thermomediterranean evergreen mixed thermophilous woodlands by the Atlantic coast to Oromediterranean shrublands above the treeline in the Guadarrama Mountains (central Spain). At each site, we analyzed pollen from moss polsters and conducted vegetation surveys. Most forested vegetation types (pinewoods, oak woods, evergreen mixed thermophilous woodlands) presented rather distinct pollen assemblages dominated by the pollen equivalents of the major tree species. Nevertheless, enhanced taxonomic resolution within Pinus and Quercus ilex-type would represent significant progress, e.g., enabling to separate Mediterranean and mountain pinewoods. Pollen spectra from shrubland and steppic communities are in general less differentiated, due to high regional pollen input associated with low local pollen production and/or the dominance of insect-pollinated species (e.g., Cytisus oromediterraneus in mountain shrublands). The results presented here will readily assist the interpretation of regional fossil pollen records from small mires/bogs/lakes and forest hollows, given their comparable pollen catchments. Comparison of modern pollen assemblages with pollen records from larger lakes and marine settings is not so straightforward, but our results suggest that marine pollen assemblages might average the pollen signature of the entire basin.

Improved Mapping of Mountain Shrublands Using the Sentinel-2 Red-Edge Band

Shrub encroachment into grassland and rocky habitats is a noticeable land cover change currently underway in temperate mountains and is a matter of concern for the sustainable management of mountain biodiversity. Current land cover products tend to underestimate the extent of mountain shrublands dominated by Ericaceae (Vaccinium spp. (species) and Rhododendron ferrugineum). In addition, mountain shrubs are often confounded with grasslands. Here, we examined the potential of anthocyanin-responsive vegetation indices to provide more accurate maps of mountain shrublands in a mountain range located in the French Alps. We relied on the multi-spectral instrument onboard the Sentinel-2A and 2B satellites and the availability of red-edge bands to calculate a Normalized Anthocyanin Reflectance Index (NARI). We used this index to quantify the autumn accumulation of anthocyanin in canopies dominated by Vaccinium spp. and Rhododendron ferrugineum and compared the effectiveness of NARI to Normalized Difference Vegetation Index (NDVI) as a basis for shrubland mapping. Photointerpretation of high-resolution aerial imagery, intensive field campaigns, and floristic surveys provided complementary data to calibrate and evaluate model performance. The proposed NARI-based model performed better than the NDVI-based model with an area under the curve (AUC) of 0.92 against 0.58. Validation of shrub cover maps based on NARI resulted in a Kappa coefficient of 0.67, which outperformed existing land cover products and resulted in a ten-fold increase in estimated area occupied by Ericaceae-dominated shrublands. We conclude that the Sentinel-2 red-edge band provides novel opportunities to detect seasonal anthocyanin accumulation in plant canopies and discuss the potential of our method to quantify long-term dynamics of shrublands in alpine and arctic contexts.

Phytolith assemblages in modern top soils under plant communities of Northern and Western Altay, Russia

We investigated 120 assemblages of phytoliths from modern top soils of 40 different plant communities of Northern and Western Altay region of Russia. The samples were collected from elevations between 360 m and 2360 m above sea level. Using statistical analyses, it was discovered that many communities produce sufficiently distinct assemblages based on standard morphotypes. Specifically we studied 6 kinds of forests (larch, spruce, fir, pine, cedar pine and birch-dominated), 3 kinds of steppes (true, meadow and petrophytic), 5 kinds of meadows (steppe-like, upland dry, wet floodplain, subalpine, alpine), alpine tundra, and mountain shrubland communities. The communities were not evenly sampled, with more redundancy in some types than in others. Using PCA, it was possible to reveal the few morphotypes most responsible for distinguishing different communities, e.g., low conical rondels, rondel sum, long cell sum, lanceolate cells with massive base, and bulliform cell sum.

Nutritional quality of kermes oak (<i>Quercus coccifera</i> L.) acorns as affected by altitude in a typical Mediterranean area

Abstract. The impact of altitudinal zone on the nutritional quality of kermes oak (Quercus coccifera L.) acorns was assessed in Xirovouni Mountain shrublands in northwestern Greece. Whole acorns were collected during autumn 2011 from 15 sites located at three altitudinal zones (i.e. lower, middle, upper). Kermes oak acorn samples were manually separated into kernel and hull and analysed for chemical composition (crude protein, CP; neutral detergent fibre, NDF; acid detergent fibre, ADF; lignin), in vitro dry matter (DM) digestibility (IVDMD), in vitro NDF digestibility (IVNDFD), digestible energy (DE), and minerals (i.e. Ca, P, K, Mg, Mn, Fe, Zn, Cu). Altitude had a negative correlation with CP, IVDMD, and IVNDFD and positively correlated to cell wall contents in both kernel and hull. Acorns growing under higher temperatures (at lower altitude) have more digestible cell wall compared to acorns growing under lower temperatures (at higher altitude) due to increased CP content and decreased cell wall content. It seems that environmental factors affect the nutritional value of acorns. Thus, goat farmers should take this into account when collecting acorns to feed their animals.

Plant community resilience in the face of fire: experimental evidence from a semi‐arid shrubland

AbstractThe ability of communities or ecosystems to recover their structure and function after a disturbance is known as resilience. According to different views, resilience can be influenced by the resource‐use strategies of the plant functional types that dominate the community or by the existence of functional redundancy within plant functional types. We investigated how the dominance of different plant functional types and species affected the resilience of a mountain shrubland after an intense fire. We took advantage from a pre‐existing long‐term removal experiment in which either whole plant functional types (deciduous shrubs, graminoids, perennial forbs and annual forbs) or the dominant species within each plant functional type were removed for 10 years. We sampled species and plant functional types cover during the first growing season after the fire. First, to test whether functional redundancy increased resilience, we analyzed the existence of functional compensation inside plant functional types. Second, to test whether the dominance of plant functional types with different resource‐use strategies affected recovery, we compared resilience at the levels of species, plant functional types and total cover, estimated on the basis of a change index and multivariate Euclidean distances. No compensation was observed in any of the plant functional types. At the level of species, we found that the assemblages dominated by conservative resource‐use strategies were the ones showing higher resilience. This was due to the high recovery of the dominant species of shrubs plant functional type. The opposite (lowest recovery of conservative resource‐use strategies) was found at the plant functional type and total cover‐levels. Our study did not support the hypothesis of resilience by functional redundancy. Instead, regeneration by buried meristems from the pre‐fire stage appeared to be the factor that most influenced recovery. Resource‐use strategies explained resilience of vegetation cover, but not of floristic composition. Regeneration traits, rather than vegetative traits or mechanism of functional compensation, appeared as the most relevant to explain the response of this system after fire.

Biocrust structure responds to soil variables along a tropical scrubland elevation gradient

Biocrusts are composed of diverse organisms including bryophytes, lichens, archaea, bacteria, cyanobacteria, microfungi, and green algae. While biocrusts are distributed worldwide, most of our knowledge comes from temperate regions, and scarce information is available from tropical regions. We aimed to: i) generate the first map of potential areas of occurrence of biocrust in Ecuador, ii) describe the structure of biocrust components along an elevation gradient predicted by our map analysis to support biocrusts. Our maps identified 9145 km2 as potential area for the occurrence of biocrusts, which represents 18% of Ecuadorian drylands. Our study site was located in mountain shrubland in southeastern Ecuador. Species richness increased with elevation and species composition was significantly different among elevation levels. The abundance of species forming biocrusts was related to several soil variables, including pH and fine texture. Our results provide insights into the importance of soil variables as drivers of biocrust composition and abundance in the tropics. Moreover, the information generated in this study could be useful in assigning conservation priorities to Ecuadorian drylands. Thus, our results help fill current gaps in our knowledge of biocrusts and add to the scant literature dealing with these organisms in tropical drylands.

Using carbon finance to support climate policy objectives in high mountain ecosystems

Carbon markets and climate finance payments are being used to incentivize the mitigation of CO2 arising from anthropogenic land-use change in forests, marine ecosystems, and lowland grasslands. However, no such consideration has been given to how these ‘carbon finance incentives’ might be applied to mountain grasslands and shrublands, ecosystems that contain a substantial amount of carbon. These incentives amount to more than US$350 billion per annum and could potentially support underfunded natural resource management (NRM) activities, which are urgently needed to address numerous stressors impacting these important ecosystems. In the mountain context, NRM activities could include adaptive grazing management, sustainable cropping, ecosystem preservation, ecosystem restoration, and engineered soil conservation measures. This article investigates the stressors, challenges, and priorities related to the NRM of carbon stocks in mountain grasslands and shrublands; why carbon markets and climate finance have not yet been utilized in this context; and, what is required to position mountain-based NRM activities as eligible for carbon finance incentives. Using surveys and interviews triangulated with a systematic literature review, the study found that carbon finance incentives are not well understood, both amongst mountain-focused experts and in the literature. The study also found the required technical methodologies, policy frameworks, and data to be largely undeveloped. This article proposes a top-down conceptual policy framework that can be used to develop key ‘enabling factors’ with the view of extending the eligibility of carbon markets and climate finance to NRM activities undertaken in mountain grasslands and shrublands in the same way that has been afforded to other ecosystems.Policy relevanceThis is the first study to explicitly highlight the important role that the mountain grasslands and shrublands might play in international climate policy, and how carbon finance mechanisms might support better NRM in these areas. It is also the first to investigate why these incentives have not been adopted thus far. The article concludes by proposing a novel top-down ‘carbon incentive enabling’ framework that could be driven by governments and mountain development focused organizations so as to capture some of the opportunities offered by carbon-based incentives, and help meet international climate policy objectives.

Food Availability, Foraging Behavior, and Diet of Autumn Migrant Landbirds in the Boise Foothills of Southwestern Idaho

Abstract. Food availability and acquisition are critical components of a stopover site's suitability, but we know relatively little about how changes in food availability affect the stopover ecology of migrating landbirds. We examined fruit and arthropod availability in three habitats, studied foraging behavior and diet, and investigated use versus availability for passerines migrating through southwestern Idaho in autumn. Hemiptera dominated foliage-dwelling arthropod communities in all three habitats, whereas Hymenoptera were most numerous among ground-dwelling arthropods. Mountain shrubland had relatively high biomass of both ground-dwelling and foliage-dwelling arthropods, whereas conifer forest had high biomass of foliage-dwelling arthropods only and shrubsteppe had high biomass of ground-dwelling arthropods only. Species' foraging behavior varied, but most species foraged in mountain shrubland more often than expected by chance. Diets of most species included a high proportion of certain Hemiptera a...

Trophic habits of feral cats in the high mountain shrublands of the Macaronesian islands (NW Africa, Atlantic Ocean)

Feral cats Felis catus Linnaeus, 1758 have contributed to the extinction of numerous native species on islands, which are clearly sources of global biodiversity. We studied the diet of this introduced predator in the Madeira and Cape Verde archipelagos, which harbour important colonies of endangered seabirds in the high mountain habitats, and compared the results with those obtained in the same habitat in the Canary Islands, Macaronesian archipelago. On Madeira, 461 prey were identified from 143 scat groups. Mammals, overall mice, constituted the basic diet appearing in 95% of cat scats. On Fogo (Cape Verde), 657 prey items were obtained from 145 scats, and mammals were also the most important prey, reaching a frequency of occurrence of 88%. Although introduced mammals were the main prey category on all Macaronesian islands, we observed variation in feral cat diet among these islands. Birds were more frequently consumed on Madeira, lizards on Tenerife (Canaries) and invertebrates on Fogo. No specific differences were observed in relation to La Palma. We suggest that the diet composition on these islands varies according to the respective availability of the different prey types.

Bird responses to fire severity and time since fire in managed mountain rangelands

AbstractBroom matorrals are subjected to extensive burning in the Pyrenees to improve grazing value, despite being a habitat of conservation interest in Europe. Our aim here is to evaluate the impact of such management practices over the long term, and of fire severity over the short term, on avifauna. Bird‐habitat stations were distributed in broom shrublands from a few months to 51 years after fire, at 1400–2100 m a.s.l. Overall, shrub cover was the main habitat variable affecting the bird community composition. The abundance trends of bird species for half a century after fire were varied, but population recovery seemed slower (especially in the Dartford warbler Sylvia undata) than it had been reported at a lower altitude. Three species of European conservation concern (Alauda arvensis, Lullula arborea and Lanius collurio) showed abundance peaks at 10–19 years after fire. This time interval showed the highest species richness, abundance and conservation value, whereas shrub cover continued to increase afterwards. The bird assemblage tended to impoverish with increasing fire severity in the first year after a fire. Our results emphasize: (1) the slow recovery of bird community of burnt mountain shrublands; (2) the need for long‐term biodiversity assessments to help improve planning of fire intervals at different altitudes; (3) the relevance of reducing fire severity due to its impact on fauna.

Predicting and mitigating weed invasions to restore natural post-fire succession in Mesa Verde National Park, Colorado, USA

Six large wildfires have burned in Mesa Verde National Park during the last 15 years, and extensive portions of burns were invaded by non-native plant species. The most threatening weed species include Carduus nutans, Cirsium arvense, and Bromus tectorum, and if untreated, they persist at least 13 years. We investigated patterns of weed distribution to identify plant communities most vulnerable to post-fire weed invasion and created a spatially explicit model to predict the most vulnerable sites. At the scale of the entire park, mature piñon–juniper woodlands growing on two soil series were most vulnerable to post-fire weed invasion; mountain shrublands were the least vulnerable. At a finer scale, greater richness of native species was correlated with greater numbers of non-native species, indicating that habitats with high native biodiversity are at the greatest risk of weed invasion. In unburned areas, weed density increased with greater soil nitrogen and phosphorus, and lower salinity. In burned areas weed density correlated with soil nitrogen status and textural class. We also evaluated the effectiveness of a variety of weed mitigation methods; aerial seeding of targeted high-risk areas with native grasses was the most effective treatment tested. We recommend a conservative mitigation plan using natives grass seed on only the most invasible sites.