Scrub Communities Research Articles

Nickel-hyperaccumulating species of Phyllanthus (Phyllanthaceae) from the Philippines

Botanical exploration on ultramafic sites in Palawan, Surigao and Zambales has resulted in the discovery of a new hypernickelophore species (nickel (Ni) concentration >1%) of Phyllanthus (Phyllanthaceae). This paper reports in detail the Ni uptake of populations of P. erythrotrichus in Candelaria, Masinloc and Santa Cruz, Zambales, and confirms the status of P. securinegoides in Taganito, Surigao del Norte, which had been analysed only through herbarium specimens, and these were compared with a known hypernickelophore, P. balgooyi, which was collected in Narra and Puerto Princesa, Palawan. Nickel content of the dried leaves, stems and root tissues was quantified using atomic absorption spectrophotometer. P. erythrotrichus and P. securinegoides both had more than 10 000 µg g–1 Ni in the leaves, whereas the roots had 1195 µg g–1 and 4636 µg g–1. P. balgooyi accumulated 6319 µg g–1 of Ni in the leaves, whereas the roots had a higher Ni concentration of up to 8116 µg g–1, respectively. All three species had values of translocation factor and enrichment factor of >1.0, implying that all species have great potential in phytoremediation, specifically, phytoextraction of Ni. These three species of Phyllanthus are prominent in ultramafic scrub communities and, hence, should be used in ecological restoration of mined-out Ni lateritic areas. The implications of the unique adaptation of these species are also discussed in relation to a conservation strategy for their natural populations.

富士山北西斜面御庭付近のカラマツ低木林はなぜ維持されるのだろうか？

富士山北西斜面御庭付近のカラマツ低木林はなぜ維持されるのだろうか？

Functional diversity reveals complex assembly processes on sea‐born volcanic islands

AbstractQuestionsDo the mechanisms driving community assembly differ between two islands of different age and history of vegetation development? How does sampling scale affect the strength that each assembly mechanism poses on the assembly of plant communities?LocationVolcanic islands (Palea Kameni and Nea Kameni) of Santorini Archipelago, Greece.MethodsFunctional diversity has been proposed as a framework for discriminating among mechanisms of community assembly, such as habitat filtering, limiting similarity and random assembly. We investigated four plant communities in two sea‐born volcanic islands. We recorded plant diversity at scales from 1 m2 to 64 m2. We calculated three indices of functional diversity: functional richness, functional evenness and functional divergence, using 26 functional traits (including vegetative characteristics, ecological preferences and regenerative characteristics). We used null model analysis to test for two different assembly mechanisms: habitat filtering and limiting similarity or random assembly.ResultsThe assemblage of the four communities was complex and did not follow a single mechanism. In most cases, finer‐scale patterns indicated randomness, while coarser scales revealed more structured communities. In the older island, the scrub community was mainly defined by limiting similarity. The therophytic community displayed a limited range of functional traits, indicating mainly habitat filtering, but within this range, the evenness of the distribution indicated limiting similarity. On the younger island, the range of traits did not differ from random. However, within this range of traits, one therophytic community showed signs of limiting similarity, while the second therophytic community displayed uneven functional trait distribution, indicating mainly habitat filtering. The three indices reflected different facets of functional diversity and were not correlated, thus we may argue that they are not redundant, and we even detected different mechanisms of assembly within the same community.ConclusionsThe functional diversity of the therophytic communities in the younger island implied no specific assembly mechanism; perhaps due to its age, the community is still at the early stages of colonization (i.e. stochastic processes, such as arrival of new species, prevail). In the older island, the lack of disturbances for a long period allowed the establishment of communities assembled by specific mechanisms, such as competition and habitat filtering.

Assessing the effects of groundwater extraction on coastal groundwater-dependent ecosystems using satellite imagery

Terrestrial vegetation that depends on the subsurface presence of water can be severely affected by groundwater extraction. We analysed Landsat imagery to assess the ecological risk posed by groundwater pumping to native vegetation on the Tomago Sandbeds, a coastal sand mass in northern New South Wales. The effect of extraction on each major vegetation community was assessed by comparing rates of evapotranspiration between extraction zones and matched areas outside the influence of extraction. We found a significant long-term change in evapotranspiration close to groundwater extraction points within most forest, woodland and scrub communities, including those not currently regarded as being wholly dependent on groundwater. We therefore suggest that management of groundwater-dependent ecosystems should not be based on degree of dependence but instead on their sensitivity to groundwater management regimes. Our approach can provide policy makers with information needed to evaluate and adjust groundwater management within groundwater-dependent ecosystems.

Altered water and nitrogen input shifts succession in a southern California coastal sage community.

Vegetation-type conversions between grasslands and shrublands have occurred worldwide in semiarid regions over the last 150 years. Areas once covered by drought-deciduous shrubs in Southern California (coastal sage scrub) are converting to grasslands dominated by nonnative species. Increasing fire frequency, drought, and nitrogen deposition have all been hypothesized as causes of this conversion, though there is little direct evidence. We constructed rain-out shelters in a coastal sage scrub community following a wildfire, manipulated water and nitrogen input in a split-plot design, and collected annual data on community composition for four years. While shrub cover increased through time in all plots during the postfire succession, both drought and nitrogen significantly slowed recovery. Four years after the fire, average native shrub cover ranged from over 80% in water addition, ambient-nitrogen plots to 20% in water reduction, nitrogen addition plots. Nonnative grass cover was high following the fire and remained high in the water reduction plots through the third spring after the fire, before decreasing in the fourth year of the study. Adding nitrogen decreased the cover of native plants and increased the cover of nonnative grasses, but also increased the growth of one crown-sprouting shrub species. Our results suggest that extreme drought during postfire succession may slow or alter succession, possibly facilitating vegetation-type conversion of coastal sage scrub to grassland. Nitrogen addition slowed succession and, when combined with drought, significantly decreased native cover and increased grass cover. Fire, drought, and atmospheric N deposition are widespread aspects of environmental change that occur simultaneously in this system. Our results imply these drivers of change may reinforce each other, leading to a continued decline of native shrubs and conversion to annual grassland.

Seasonal water use by deciduous and evergreen woody species in a scrub community is based on water availability and root distribution

AbstractIn a seasonally dry plant community of central Florida, USA, that experiences water limitation in the dry season and high water availability in the wet season, we first tested whether evergreen woody species shift from shallow water in the wet season to deep water in the dry season. Second, we tested whether deciduous woody species restrict water uptake to the shallow soil during the wet season and cease water uptake during the dry season. To address these questions, we measured water source use of two deciduous and three evergreen species over 13 months using stable isotopes. As hypothesized in previous studies, we showed that leaflessness in deciduous plants is an important source of stem water isotopic fractionation. Therefore, we compared stable isotope ratios of stem water only when deciduous species had leaves and found that all species, except the evergreen Lyonia ferruginea, used proportionally the same water sources. Early dry season water use was based on water availability for all species except L. ferruginea, and deep soil (50–150 cm) was the most important water source. During the late dry and wet seasons, water uptake from each soil layer was based on its respective proportion of fine roots. Nevertheless, deep water remained an important water source throughout the year. This study clearly demonstrates the limitations of using stable isotopes of stem water when comparing deciduous versus evergreen species. Further, this study is the first to directly quantify depth of water uptake via isotope analysis and couple these findings with root distribution. Copyright © 2014 John Wiley & Sons, Ltd.

Using Comparative Biogeography to Retrace the Origins of an Ecosystem: The Case of Four Plants Endemic to the Central Florida Scrub

Premise of research. Plant communities assemble through historical, adaptive, and stochastic processes, with their relative contributions varying among communities. This study traces the origin of the highly threatened Florida scrub ecosystem, a series of relic sand dunes with exceptionally high endemism. We used dated phylogenies with four endemic angiosperms to test two hypotheses on the origins of the Florida scrub: the western hypothesis, which emphasizes the role of mid-Pliocene fragmentation of the xeric belt between southwestern North America and Florida, and the eastern hypothesis, which emphasizes the glacial cycles of the Pleistocene. Methodology. Augmenting existing phylogenies, we sequenced the nuclear internal transcribed spacer region and several plastid loci of species of Prunus (Rosaceae), Polygala (Polygalaceae), Persea (Lauraceae), and Ilex (Aquifoliaceae) to phylogenetically place the Florida scrub endemics and identify their putative sister taxa. We used topology tests, ancestral area reconstruction analyses, and time-calibrated trees to evaluate the western and eastern hypotheses both geographically and temporally. Pivotal results. Results for Polygala and Ilex support the eastern hypothesis for the origin of the central Florida endemics, while data for Persea and Prunus are ambiguous. However, all species show an eastern ancestral distribution to some degree. Molecular dating analyses suggest that extant Ilex opaca populations diverged in the Pleistocene, with older Pliocene origins for the North American Persea clade, Polygala lewtonii, and Prunus geniculata. Conclusions. Taken together, our results support eastern North America as the dominant origin of the plant species of the central Florida scrub. However, contrary to the current eastern hypothesis, molecular dating suggests that the origins of the four endemics predate the last glacial cycles. These results have implications for the age of the Florida scrub itself as well as its component species, suggesting that the Florida scrub or its precursor existed before Pleistocene glaciation. Furthermore, the more ancient age of this assemblage of species than envisioned by most accounts suggests that interspecific interactions in this community are not recently formed (i.e., since the end of the Pleistocene) and may have been established over much longer periods of geological history. These fundamental associations argue for enhanced conservation efforts of both the individual species and the persistent remnants of the scrub community.

不同植被恢复类型的土壤肥力质量评价

PDF HTML阅读 XML下载 导出引用 引用提醒 不同植被恢复类型的土壤肥力质量评价 DOI: 10.5846/stxb201306111672 作者: 作者单位: 华南农业大学林学院,华南农业大学林学院,华南农业大学林学院,华南农业大学林学院,华南农业大学林学院 作者简介: 通讯作者: 中图分类号: S714.8 基金项目: 广东省林业科技创新专项（2010KJCX012-02，2011KJCX031-02） Soil fertility quality assessment under different vegetation restoration patterns Author: Affiliation: College of Forestry, South China Agricultural University,College of Forestry, South China Agricultural University,College of Forestry, South China Agricultural University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:科学确定森林土壤肥力指标并进行肥力质量的评价，对立地生产力和多目标森林经营的研究有着重要意义。以采伐（径级12 cm择伐）迹地上发育来的稀树灌丛、针叶林、针阔混交林和常绿阔叶林为研究对象，进行每木调查与群落分析，并比较各群落土壤因子间的差异，用典范对应分析（CCA）和因子分析对土壤肥力质量进行定量评价。结果表明，CCA可以有效地筛选土壤肥力质量指标，有助于质量指标的科学确定；土壤肥力质量综合评价分值为稀树灌丛（0.438） > 常绿阔叶林（0.414） > 针阔混交林（-0.170） > 针叶林（-0.331）；演替初期（19 a）的植被恢复并未使土壤结构发生明显变化，土壤肥力质量是下降的；无人为干扰的3种群落类型，针叶林表现为更高的生物量积累，而天然更新的常绿阔叶林则更有利于生物多样性的增加与土壤养分的保蓄。 Abstract:Soil fertility quality assessment based on scientifically determined indicators has significant implications for the study of stand productivity and multi-objective forest management. We carried out plant census and community analysis, and compared soil physicochemical properties among forest communities in Kanghe Nature Reserve. The four community types, i.e., scrub, evergreen broadleaved forest, coniferous-broadleaved mixed forest, and coniferous forest, represented different vegetation restoration patterns originating from a selective-logging (at 12 cm diameter) event on the subtropical evergreen broadleaved forest. The main soil factors influencing tree composition and distribution were screened by Canonical Correspondence Analysis (CCA), which were subsequently used to build the minimum data set (MDS). Soil fertility quality was quantitatively assessed with Factor Analysis on MDS.The results showed that distribution of tree species was unevened. With the lowest species richness, the coniferous forest was exclusively dominated by Cunninghamia lanceolata, whereas in the most species rich evergreen broadleaved forest, codominant tree species existed. Average tree DBH (diameter at breast height) decreased successively among coniferous forest, coniferous-broadleaved mixed forest and evergreen broadleaved forest.Soils were highly acidic (pH < 5.0) and the content of AvK, ExMg, AvMn, AvZn and AvFe had no significant difference(P > 0.05)across the four forest communities. A lower canopy density due to less canopy trees resulted in the lower soil moisture content in the scrub community, which had a higher mineral element content than other vegetation patterns as a whole. Distribution of trees was closely related to soil environmental factors, but the results of CCA indicated that there was no significant correlation (Monte Carlo Test,P > 0.05) between composition and distribution of tree species and the seven soil factors, i.e., AN, ExCa, AvK, TP, ST, AP and NCP, which should be excluded when building the MDS. Therefore, the findings revealed that CCA was an effective tool for screening soil fertility quality indicators and establishing MDS by demonstrating the effect of soil fertility on plant patterns.Factor analysis was applied on MDS to assess the fertility quality and the cumulative variance explained by five principal components was 84.67%, indicating this evaluation method was reliable. The integrated soil fertility quality assessment scores for scrub, evergreen broadleaved forest, coniferous-broadleaved mixed forest, and coniferous forest were, in a descending order, 0.438, 0.414, -0.170, and -0.331, respectively. Vegetation restoration did not obviously change soil structural parameters, such as soil texture, capillary porosity, non-capillary porosity, and bulk porosity, however, soil fertility quality declined in the early succession stage (19 a). In the three community types without human disturbance, coniferous forest had the highest biomass accumulation, whereas evergreen broadleaved forest from natural regeneration was more conducive to the increase of biodiversity and soil nutrient accumulation. Site-specific indicators, including soil physicochemical factors and biological factors, should be selected in future assessment of soil fertility quality. The appropriate quantitative ecological methods could make the determination of evaluation index more scientific. 参考文献 相似文献 引证文献

New Records of Marginal Locations for American Pika (Ochotona princeps) in the Western Great Basin

We describe 46 new site records documenting occupancy by American pika (lOchotona princeps) at 21 locations from 8 mountain regions in the western Great Basin, California, and Nevada. These locations comprise a sub- set of sites selected from regional surveys to represent marginal, isolated, or otherwise atypical pika locations, and to provide information for assessing environmental tolerance limits. Several locations are known from historic observations (Madeline Plain, Bodie Mtns., Wassuk Mtns., Mono Craters) and are included here to update current status. Site eleva- tions range from 1848 m to 3392 m; relative to the broad range of pika sites in the region, the new locations have cli- mates that are 2—4 °C warmer and receive approximately half the annual precipitation. Sites are located in lava flows and domes, inselbergs (isolated, rocky exposures on a small hill), eroding bedrock, rock-glacier till, talus slopes, and anthro- pogenic roadbed armaments and mining ore dumps. Several sites are situated in uncommon vegetation contexts, for example, montane desert scrub communities or locations where vegetation adjacent to taluses is sparse or lacking. Prox- imity to surrounding pika habitats (as a measure of marginality) was evaluated based on relative talus distribution pat- terns for 0.5-km, 2.5-km, and 5.0-km circular areas nested around each site. Seven idealized, schematic spatial patterns were used to assess potential connectivity among sites, ranging from “island” (no other talus within the respective areas) to “even” (many talus patches regularly distributed). Applying this approach to the 21 sites demonstrated a simple method for qualitatively assessing pika habitat relative to dispersal potential and metapopulation viability and also revealed complexities of biogeographic patterns related to marginality.

Dissecting the Effects of Simulated Cattle Activity on Floristic Composition and Functional Traits in Mediterranean Grasslands

Livestock exerts direct and indirect effects on plant communities, changing colonization and extinction rates of species and the surrounding environmental conditions. There is scarce knowledge on how and to what extent these effects control the floristic and functional composition of plant communities in grasslands. We performed an experiment that included several treatments simulating trampling, defoliation, faeces addition and their combinations in a Mediterranean scrub community grazing-abandoned for at least 50 years. We monitored the plots for four years, and collected data on species composition, photosynthetically active radiation (PAR) and red∶far-red ratio (R∶FR), soil moisture and compaction. We estimated community weighted means (CWM) for height, habit, life cycle, seed mass and SLA. Neither compaction nor soil moisture were modified by the treatments, while PAR and R∶FR increased in all treatments in comparison to the Control and Faeces treatments. The floristic composition of all treatments, except for Faeces, converged over time, but deviated from that of the Control. The functional traits displayed the trends expected in the presence of grazing: loss of erect species and increased cover of short species with light seeds, with rosettes and prostrate habit. However, contrary to the results in literature, SLA was lower in all the treatments than Control plots. Like the results for floristic composition, all treatments except for Faeces converged towards a similar functional composition at the end of the four year period. The results of this study show the initial evolution of a Mediterranean plant community in the presence of grazing, driven primarily by the destructive action of livestock. These actions seem to directly affect the rates of extinction/colonization, and indirectly affect the light environment but not the soil conditions. However, their effects on floristic and trait composition do not seem to differ, at least at the small spatio-temporal scale.

Contribution to the knowledge of some rare plant communities from the southwestern Iberian System

Several herbaceous communities from the southwestern Iberian System poorly known from the phytosociological perspective are documented and framed into their correspondent syntaxa, including calcareous (Epipactido palustris-Primuletum farinosae) and siliceous sedge fens (Caricetum echinato-nigrae), Nardus swards (Genisto anglicae-Nardetum strictae), and rush meadows (Deschampsio hispanicae-Juncetum effusi and Hyperico undulati-Juncetum acutiflori). We also validate an unpublished association for thyme scrub communities of the endemic Thymus leptophyllus subsp. izcoi, proper from siliceous substrates in the north and southwestern Iberian System.

He coastal vegetation of the portuguese divisory sector: dunes, cliffs and low scrub communities

The Portuguese Divisory Sector is an original biogeographical unit within the Gaditano-Onubo-Algarvish Province of the Mediterranean chorological region. There are four superdistricts along its coastal area: "Olissiponense", "Sintrano", "Costeiro Português" (Portuguese Coastal) and "Berlenguense". The portuguese Coastal superdistric has not been sufficiently studied; it is the largest and its transitional biogeographical character lies between those of the Mediterranean and Eurosiberian regions due to its paleo-ecological history and joint position in relation to Atlantic and Mediterranean floristic migratory pathways. Due to these multiple influences a wealth of original taxa and syntaxa are found there which make large areas of the region suited for biodiversity conservation. In this work we characterise briefly 27 plant associations of dunes and sea-cliffs. Endemic or protected taxa and communities are cited. We also propose four new syntaxes.

Composición vegetal de la estación biológica de la UCM ‘Finca de Ontalba’

Se ha llevado a cabo un estudio sobre la vegetación de la recientemente designada Estación Biológica Complutense ‘Finca de Ontalba’, localizada en la Sierra de Guadarrama (N Madrid). Identificamos 12 comunidades vegetales agrupadas en siete grandes tipos de vegetación: 1) Comunidades higrófilas y acuáticas; 2) Prados; 3) Comunidad pionera de suelos alterados; 4) Vegetación herbácea nitrófila de líndero de bosque; 5) Vegetación herbácea de lindero de bosque; 6) Comunidad arbustiva de orla de bosque; y 7) Vegetación forestal. Se señala el interés de la Estación para trabajos de investigación. Su campo de aplicación incluye sucesión primaria, ambientes anfibios, gradientes de humedad del suelo, ecotonos, y ambientes forestales. La Estación Biológica alberga, además, un tipo de hábitat listado en la Directiva 92/43/CEE que corresponde a cursos de agua de llanura o montanos con vegetación de Ranunculion fluitantis y Callitricho-Batrachion (hábitat 3260).

Mycorrhizal colonization of Palafoxia feayi (Asteraceae) in a pyrogenic ecosystem

Although a number of factors have predictable effects on mycorrhizal colonization, determining generalized patterns for some variables have remained elusive. In particular, fire has been identified as a major event that may influence plant-mycorrhiza interactions, yet efforts to date have yielded contradictory results. Here, we assess the impact of fire on mycorrhizal colonization in Palafoxia feayi, a plant commonly found in the fireswept, nutrient-poor scrub community of central Florida. We determined soil nutrient conditions and percent colonization patterns for plants growing in replicate plots that were burned 1 to 15years previously. The results showed a negative relationship between mycorrhizal colonization and time since fire, but there was no effect of fire return interval (lapsed time between successive fires). Soil nutrient analyses corroborated previous studies and showed no change in soil nutrients following fire. In contrast to previous studies of mycorrhizal colonization in Florida scrub, we conclude that fire can affect arbuscular mycorrhizal fungi colonization and we speculate that this is mediated by light availability.

Genome sequence of dwarf birch (Betula nana) and cross‐species RAD markers

New sequencing technologies allow development of genome-wide markers for any genus of ecological interest, including plant genera such as Betula (birch) that have previously proved difficult to study due to widespread polyploidy and hybridization. We present a de novo reference genome sequence assembly, from 66× short read coverage, of Betula nana (dwarf birch) - a diploid that is the keystone woody species of subarctic scrub communities but of conservation concern in Britain. We also present 100 bp PstI RAD markers for B. nana and closely related Betula tree species. Assembly of RAD markers in 15 individuals by alignment to the reference B. nana genome yielded 44-86k RAD loci per individual, whereas de novo RAD assembly yielded 64-121k loci per individual. Of the loci assembled by the de novo method, 3k homologous loci were found in all 15 individuals studied, and 35k in 10 or more individuals. Matching of RAD loci to RAD locus catalogues from the B. nana individual used for the reference genome showed similar numbers of matches from both methods of RAD locus assembly but indicated that the de novo RAD assembly method may overassemble some paralogous loci. In 12 individuals hetero-specific to B. nana 37-47k RAD loci matched a catalogue of RAD loci from the B. nana individual used for the reference genome, whereas 44-60k RAD loci aligned to the B. nana reference genome itself. We present a preliminary study of allele sharing among species, demonstrating the utility of the data for introgression studies and for the identification of species-specific alleles.

Molecular evidence indicates that subarctic willow communities in Scotland support a diversity of host-associated Melampsora rust taxa

Rare and threatened subarctic willow scrub communities in the UK are the subject of ongoing conservation programmes, yet little is known about the diversity of fungal taxa that they support. Isolates of the rust genus Melampsora were sampled from 112 leaves of eight subarctic willow (Salix) taxa and their hybrids from twelve sites in the UK. In order to determine the number of Melampsora taxa present in the samples, isolates were sequenced for the Internal Transcribed Spacer (ITS) region of rDNA and data were subject to phylogenetic analysis. Maximum likelihood and Bayesian analysis indicated that the isolates fell into three strongly supported host-associated clades. Clade I contained only isolates from Salix herbacea and was distinguished morphologically by dense urediniospore echinulation and thin cell walls. Clade II contained isolates from Salix arbuscula and Salix reticulata only. These could not be distinguished morphologically from isolates in Clade III which were found on Salix lapponum, Salix myrsinites, Salix myrsinifolia, Salix aurita, Salix lanata, and their hybrids. Clade II was most distinct in ITS sequence, differing by 50 bases from Clades I and III, while the latter clades differed in sequence by only 24 bases on average. Clades I and III are likely to represent the previously recognised taxa Melampsora alpina Juel 1894 and Melampsora epitea Thüm. 1879 respectively, but Clade II has not apparently been described before. Significant differences in the intensity of infection by isolates of Clade III were found among different Salix species at a single site, suggesting either differences in resistance among Salix taxa, or the presence of further cryptic taxa within Clade III. The study illustrates the power of molecular phylogenetic analysis to reveal cryptic biodiversity within Melampsora, and suggests that conserving Salix host diversity within subarctic willow communities will ensure that a diversity of associated Melampsora taxa is maintained.

Patterns of Aboveground Biomass Regeneration in Post-Fire Coastal Scrub Communities

An evaluation of ALOS PALSAR (Phased Array type L-band Synthetic Aperture Radar) data for shrub height and aboveground biomass (AGB) estimation has been performed in scrub-dominated ecosystems of central coastal California. Comparison between AGB field measurements and SAR estimations showed a correlation coefficient of R2 = 0.53 for the HV polarization. Post-fire AGB regeneration was examined two years after the Big Sur Basin Complex fire of 2008. In 2009, the average patch size of AGB density classes between 20-40 Mg ha-1 and 50-70 Mg ha-1 was 0.49 ha and 0.09 ha, respectively. In 2010, patch sizes in these same two AGB density classes increased to averages of 0.8 ha to 0.15 ha, respectively. No strong saturation in the SAR-AGB relationship was found, which indicated the potential for more advanced applications of L-band SAR data for coastal ecosystem AGB mapping.

Fusion of Hyperspectral and L-Band SAR Data to Estimate Fractional Vegetation Cover in a Coastal California Scrub Community

A study was carried out to investigate the utility of airborne hyperspectral and satellite L-band Synthetic Aperture Radar (SAR) data for estimating fractional coverages of herbaceous, coastal scrub, and bare ground cover types on the central California coast. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imagery collected in September of 2008 and Phased Array L-band SAR (PALSAR) (HH- and HV-polarizations) captured in April and July of 2008 were combined for vegetation cover mapping. Hyperspectral features, computed as AVIRIS indices (NDVI, TCARI/OSAVI, and PRI), and textural information (energy, contrast, homogeneity, and fractal dimension) produced by L-band SAR were fused together to generate a new feature space. We used global Ordinary Least Squares (OLS) linear regression to integrate and decompose the new feature space for fractional vegetation mapping. Ground measurements of fractional cover were collected from plots located within the U.S. Forest Service’s Brazil Ranch study site for validation of the OLS model predictions. Significant linear relationships were found between fractional cover mapping from remote sensing and the ground-truth data. The estimation accuracy of fractional coverage mapping from remote sensing in terms of Root Mean Square Error (RMSE) was 17%, 12%, and 10%, for the herbaceous, coastal scrub, and bare ground covers, respectively. Decomposition results showed that textural information from L-band SAR strongly supported herbaceous and coastal scrub fractional mapping, while indices features from AVIRIS significantly improved mapping of herbaceous cover and bare ground.

Seasonal priority effects: implications for invasion and restoration in a semi‐arid system

Summary1. The timing of seasonal activity (i.e. phenology) may play an important role in plant invasions. In ecosystems characterized by seasonal rainfall, early‐active exotic species may pre‐empt resources and attain competitive dominance via a seasonal ‘priority advantage’. Exotic annual grasses in California are often active earlier than native species, potentially because they possess greater germination plasticity. While these problematic invaders may usually benefit from having early phenology, their flexible germination cues might be manipulated as a restoration strategy to germinate seeds far in advance of favourable growing conditions, leading to a ‘priority disadvantage’.2. We manipulated the start of the growing season in an invaded California coastal sage scrub community characterized by a Mediterranean‐type climate to (i) identify whether early‐season phenology confers a performance advantage and (ii) test whether rainfall timing could be manipulated to favour native species. We compared the performance of seeded native and exotic focal species under ambient rainfall timing (winter rains) vs. with a pre‐growing season (late‐summer) watering event.3. Under ambient rainfall timing, exotic annual grasses and forbs germinated earlier and reached higher levels of abundance than native species, consistent with a seasonal priority advantage. Many exotic annual grasses germinated with pre‐season watering, but none survived until the onset of natural rains. Observations suggest that early‐germinating seedlings suffered mortality via herbivory. The watering pulse thus depleted the exotic seedbank, fewer exotic individuals germinated with winter rains, and exotic species attained lower abundance than under the natural rainfall timing.4. Native species, whether annual or perennial, did not germinate with the pre‐season watering pulse, suggesting they may have more constrained germination cues than the exotic species.5. Synthesis and applications. Our results suggest that phenology is an important factor influencing invasion success, and that this could be manipulated to favour native species. Manipulation of the start of the growing season, for example through a pre‐growing season watering event, could be a successful restoration strategy for native species in some ecosystems.

Distribution patterns, ecological characteristic and conservation status of endemic plants of Tadzhikistan – A global hotspot of diversity

Based on literature data and own fieldwork in Tadzhikistan (Middle Asia), the taxonomic structure, distribution, habitat preferences as well as conservation state of a group of 1486 species of vascular plants of endemic and sub-endemic character are presented. In addition to verifying the number of endemics, the present study has shown that Tadzhik endemics are the most numerous in the northwest of the country, in the Gissar-Darvasian and Zeravshan regions. An analysis of average richness of endemics per surface unit has revealed that Gissar-Darvasian F is the richest area. An assessment of the taxonomic similarity of geobotanical regions based on endemic species composition has shown that differences in general correspond to the geobotanical subdivision of Tadzhikistan. The endemics studied are stenochoric species with a distributional area for endemics sensu stricto varying between ca. 486 and 111,489 km 2 (average 12,478 km 2) and between 11,830 and 349,473 km 2 (mean 74,097 km 2) for sub-endemics. The habitats harbouring the richest group of endemics are steppes and semi-savannas, alpine forests, xerothermophilous shrubs, alpine meadows and swards. The most numerous endemic groups have been recorded from altitudes of around 1800, 2000 and 2500 m above sea level. The most important threats to Tadzhik endemics are intensive grazing and erosion of soils, as well as denudation. Vegetation types most vulnerable to human impact are forest and scrub communities. For effective protection of endemics a greater involvement of international organisations as well as legal and organisational changes in the Republic of Tadzhikistan are needed.