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  • Volume 10 Issue 5
    An autumn alpine meadow in Amdo County, north Tibet Autonomous Region, China. The flora is dominated by Kobresia robusta, Maximowicz and Kobresia pygmaea, Cyperaceae. In the center of the picture is a Thermokarst pond. Photo taken by Dr. Xiaodong Wu.
    Research Articles
    David García-Callejas, Roberto Molowny-Horas, Javier Retana
    2017, 10 (5): 731-743.
    Abstract ( 148 )   PDF   Save
    Aims Distribution and abundance patterns of species arise from the spatiotemporal dynamics of demographic processes. Population rates of birth, death, growth and patterns of dispersal are, in turn, influenced by environmental conditions and biotic interactions. However, current approaches for modelling large-scale geographical patterns often bypass these simple premises. Centred in the mainland territory of Spain and using Pinus halepensis as a case study, our goal was to gain insight into the main drivers affecting local demographic processes, and how large-scale distribution and abundance patterns are shaped by these local variations in vital rates.
    Methods We applied the integral projection methodology to develop a spatially explicit demographic model of tree species in mainland Spain, using individual-level data from a national forest inventory. In our integral projection model, environmental conditions and competitive interactions influence the survival, growth and reproduction of trees, and we model explicitly the dynamic colonization of new patches. With this framework, the projected distribution and abundance patterns of P. halepensis up to 2090 were evaluated under two different climate scenarios.
    Important findings When environmental conditions were kept constant, populations tended to decrease in net number of adults and to increase in net basal area, thus consisting in fewer and bigger individuals. Accounting for climate change in our simulations exacerbated the trend in mortality, causing widespread losses in number of trees, and few locations maintained populations of>100 adult individuals per hectare. The expected increase in mortality under climate change, on the other hand, prompted a higher degree of regeneration via the release of niche space, although not enough to maintain current abundance levels. Colonization spatial patterns did not vary significantly with climatic conditions, but the species was able to increase its distribution under climate change more than in a constant climate scenario. Our approach yields relevant information at different spatial scales, from plot-level processes to large-scale abundance patterns. With it, we clearly indicate the strong role that climate change could have in shaping future forest communities through its differential influence on demographic processes.
    Nan Cong, Miaogen Shen, Shilong Piao
    2017, 10 (5): 744-752.
    Abstract ( 159 )   PDF   Save
    Aims Information about changes in the start and end of the vegetation growing season (SOS and EOS) is crucial for assessing ecosystem responses to climate change because of the high sensitivity of both to climate and their extensive influence on ecological processes in temperate and cold regions. Climatic warming substantially advanced SOS on the Tibetan Plateau from 1982 to 2011. However, it is unclear why EOS showed little delay despite increasing temperature over this period.
    Methods We used multiple methods to determine EOS from the satellite-observed normalized-difference vegetation index and investigated the relationships between EOS and its potential drivers on the Tibetan Plateau over 1982–2011.
    Important findings We found a slight but non-significant delay in regionally averaged EOS of 0.7 day decade-1 (P = 0.18) and a widespread but weak delaying trend across the Plateau over this period. The inter-annual variations in regionally averaged EOS were driven mainly by pre-season temperature (partial R = 0.62, P < 0.01), and precipitation and insolation showed weak impact on EOS (P> 0.10). Pre-season warming delayed EOS mainly in the eastern half and north-western area of the plateau. In the south-west, EOS was significantly and positively related to SOS, suggesting potentially indirect effects of winter weather conditions on the following autumn's phenology through regulation of spring phenology. EOS was more strongly related with pre-season temperature in colder and wetter areas, reflecting vegetation adaptation to local climate. Interestingly, pre-season temperature had weaker delaying effects on EOS for vegetation with a shorter growing season, for which SOS had a stronger control on inter-annual variations in EOS than for vegetation with a longer growing season. This indicates that shorter-season Tibetan Plateau vegetation may have lower plasticity in adjusting the length of its growing season, whenever it begins, and that climate change is more likely to shift the growing season than extend it for that vegetation.
    Frank M. Thomas, Michael Jeschke, Ximing Zhang, Petra Lang
    2017, 10 (5): 753-764.
    Abstract ( 151 )   PDF   Save
    Aims Along Central-Asian rivers in arid regions, lowering of the groundwater level constitutes a major threat to the riparian forests, whose tree layers are dominated by Euphrates poplar (Populus euphratica). Some of these fragile ecosystems are supplied with additional ('ecological') water for protection and conservation. We investigated interrelationships among groundwater distance, stand structure and above-ground wood production (at the tree and the stand level) in P. euphratica stands along a groundwater gradient (distances of 2.0–12.0 m) that also included a plot supplied with 'ecological water'.
    Methods We measured the height, diameter at breast height and basal area of poplar trees and determined the annual above-ground wood production for the three most recent years on the basis of tree-ring analyses and allometric regressions at three sites at the upper, middle and lower reaches of the Tarim River, Xinjiang, NW China.
    Important findings The distribution of age classes differed significantly among the plots: in accordance with their life histories, stands growing at a larger distance to the groundwater harboured a larger fraction of old trees (>80 years) and, in most cases, a smaller fraction of young trees (≤20 years). The annual above-ground wood production per ha was highest on a plot with a short groundwater distance (2.0 m; maximum of the 3-year investigation period: 3.0 t ha-1 a-1) and lowest, at a plot with a large distance to the water table (6.6 m; minimum: 0.23 t ha-1 a-1). However, the plot located close to the groundwater (and to the river) at the middle reaches exhibited a relatively large interannual variation in above-ground wood production, which can be attributed to interannual variations in the river discharge. At the middle and the lower reaches, these interannual variations on plots with the most favourable water supply were even more obvious at the tree level. For the fraction of mature trees (60–99 years old), no significant differences in above-ground wood production were found between the plots with the most and the least favourable water supply. Overall, the productivity at the stand level was most closely correlated with the stand density (number of trees per ha, tree cover percentage). Productivity was negatively related to tree age, whereas groundwater distance alone was not a good predictor of above-ground wood production. In conclusion, vigorous growth of P. euphratica is possible at sites with groundwater distances of up to 12 m. Supply with 'ecological water' may be beneficial to trees growing at groundwater distances not larger than ~6 m. However, allocation of water should focus on stands with a short distance to the groundwater because only under these conditions, natural generative reproduction of the poplars is possible.
    Rita de Cássia Quitete Portela, Alexandra dos Santos Pires, Maria Isabel Guedes Braz, Eduardo Arcoverde de Mattos
    2017, 10 (5): 765-770.
    Abstract ( 142 )   PDF   Save
    Aims Knowledge of species richness is of prime importance to both basic and applied aspects of ecological studies. However, quantifying plant species richness in the tropics is potentially time-consuming because of high species diversity. Plant species richness estimates are also frequently biased, because many rare species are not detected. To address these problems, the use of a variable area method has been proposed as an alternative to fixed area methods, but its applicability to plants with aggregated distributions has been questioned based on simulation studies. We use empirical data to compare the efficiency and accuracy of a variable area method and a fixed area method for estimating species richness, density and basal area for plants with aggregated distributions, using palms as a model taxon.
    Methods Adult palms were sampled in twenty 10×30 m transects in an Atlantic Forest in Rio de Janeiro state, Brazil. All individuals were considered in the fixed area method, while in the variable area method only the first six adults in each transect were sampled; in this case, transect length was defined according to the distance of the sixth adult from the beginning of the transect. When fewer than six individuals were observed in a given transect, transect length was extended up to 50 m to search for additional individuals. The efficiency of both methods was compared based on species rarefaction curves, using the Chao 1 statistic (for abundance data). For each species we calculated mean density per transect and basal area, according to each sampling method. Sampling effort in terms of the number of individual plants and the area necessary to characterize maximum species richness in each sampling method, as well as mean time taken to sample a single transect, were compared as measures of efficiency.
    Important findings An accurate estimate of species richness was achieved using both methods, but in the variable area method, a quarter of the number of individuals and half the area was sufficient to characterize maximum species richness. Density and basal area did not differ between methods for any of the species studied. In the fixed area method sampling effort was 90min per transect, whereas in the variable area method it was 30min per transect. The variable area method, with its faster assessment of palm species richness, should facilitate greater spatial representativeness by making it easier to sample a larger number of plots at different spatial scales. We thus find sufficient evidence to recommend the variable area method for rapid and robust evaluations of species richness for palms with aggregate distributions, as well as for other plants with similar spatial patterns, in tropical forests.
    Andreza Viana Neri, Gladson Ramon Alves Borges, João Augusto Alves Meira-Neto, Luiz Fernando Silva Magnago, Ian Michael Trotter, Carlos Ernesto G. R. Schaefer, Stefan Porembski
    2017, 10 (5): 771-779.
    Abstract ( 282 )   PDF   Save
    Aims The vegetation on Brazilian Páramos consists of assemblages that are driven mainly by the influence of strong environmental filtering. It is very important to understand the effect of environmental variation on taxonomic diversity and on functional diversity. Considering the lack of information about the functional diversity in Brazilian Páramos, we analyzed for the first time the effects of altitude and edaphic attributes on functional traits, as well as on taxonomic and functional diversity. We also wanted to answer the questions: Which ecological strategies are favorable in high-altitude grassland? Does soil attributes determine distributions of traits in high-altitude grassland? Considering the studied altitudinal gradient is altitude an important variable in the community assembly?
    Methods The study was conducted on three mountains: Mammoth (1850 m), Elephant (1790 m) and Totem (1690 m) in Serra do Brigadeiro State Park, Minas Gerais State, Brazil. Those mountains represent the 'Serra das Cabe?as', a smaller ridge that is surrounded by the Atlantic Forest, one of the 25 hotspot of biodiversity. The samples were taken using 100 plots of 1 m 2 per mountain that were randomly distributed. All plants except mosses were sampled. The taxonomic diversity was evaluated using richness, Shannon diversity, effective number of species and Pielou evenness. For the functional diversity, we considered the functional richness, functional evenness and functional divergence. Generalized linear models (GLM/Poisson and quasi-Poisson) were used to evaluate the effect of abiotic variables (altitude, soil depth and soil chemical attributes) on biotic variables (number of species and individuals, life form, dispersal and fruit type) and ordinary least squares regression to evaluate the effect of abiotic variables on the functional and taxonomic diversity.
    Important findings The soil variables presented a considerable edaphic gradient associated with altitude. The soil in Serra das Cabe?as plays an important role for the plant diversity: richness and diversity index were positively related with fertility. With regard to the life form, nanophanerophytes tended to increase with altitude and soil depth, while therophytes tended to decrease with altitude. The dispersal type was also associated with the abiotic variables: autochory decreases with altitude, while zoochory increases. Functional richness increases with fertility and the functional evenness with altitude. The studied gradient showed that altitude is working as a filter for functional traits and indices and is, together with soil attributes, an important determinant for the distribution of plants on Brazilian Páramos .
    Shiqin Xu, Xibin Ji, Bowen Jin, Jinglin Zhang
    2017, 10 (5): 780-790.
    Abstract ( 154 )   PDF   Save
    Aims Root architecture is a crucial determinant in the water use of desert shrubs. However, lack of integrated research on the root functional type and water uptake dynamic hinders our current understanding of the water-use strategies of desert species.
    Methods A field experiment was conducted to investigate the root functional type of three dominant desert species, Haloxylon ammodendron, Nitraria tangutorum and Calligonum mongolicum, and the dynamics of their root water uptake. The stem sap flow and microclimate were monitored, and the intact root systems of these shrubs were excavated in their native habitats on the oasis-desert ecotone of northwestern China during the summer of 2014.
    Important findings Based on root functional type, H. ammodendron is phreatophytic, while N. tangutorum and C. mongolicum are non-phreatophytic species, which means H. ammodendron can utilize multiple potential water sources, N. tangutorum and C. mongolicum mainly utilize shallow and middle soil water. The average root water uptake rates (RWU) of H. ammodendron, N. tangutorum and C. mongolicum were 0.56 (±0.12), 1.18 (±0.19) and 1.31 (±0.30) kg m ?2 h-1, respectively, during the experimental period; the contributions of night-time RWU to total water uptake amount for the corresponding species were 12.7, 2.9 and 10.6%, respectively. The diurnal and seasonal dynamics of RWU in the three species were significantly different (P < 0.05), and closely related to environmental variables, especially to photosynthetically active radiation and vapor pressure deficit. Our results suggested that the three species have distinct water-use patterns in combination with the patterns of root distribution, which may alleviate water competition during long-term water shortages. H. ammodendron appears to be more drought tolerant than the other species due to its use of multiple water sources and stable water uptake rates during growing season.
    Lai Jiang, Suhui Ma, Zhang Zhou, Tianli Zheng, Xingxing Jiang, Qiong Cai, Peng Li, Jianxiao Zhu, Yide Li, Jingyun Fang
    2017, 10 (5): 791-799.
    Abstract ( 191 )   PDF   Save
    Aims Soil respiration is one of the most important components in the carbon (C) cycle in terrestrial ecosystems. To investigate the contribution of each component of C cycle to the total soil C efflux, we quantified the rates of litter, root, and other mineral soil respiration from 2012 to 2014 in the primary and secondary tropical mountain rain forests in Hainan Island, China.
    Methods The seasonal dynamics of soil (R s), non-litter (R NL) and non-root (R NR) respiration rates were measured using an automatic chamber system (Li-8100). Litter removal and root removal treatments were used to assess the contribution of litter and roots to belowground C production. We estimated the annual C efflux of each component of soil respiration in primary and secondary forests using a temperature-based exponential model and analyzed the impact of each component in each forest type.
    Important findings The annual total soil C efflux was significantly higher in the primary rain forest (1567±205g C m ?2 yr-1) than that in the secondary forest (1300±70g C m ?2 yr-1, P < 0.05). The litter, root, and mineral soils contributed 22% (349±185g C m ?2 yr-1), 38% (589±100g C m ?2 yr-1), and 40% (628±128g C m ?2 yr-1) to the total soil C efflux in primary rain forest, respectively. In secondary forest, these three components contributed 11% (148±35g C m ?2 yr-1), 45% (572±259g C m ?2 yr-1), and 44% (580±226g C m ?2 yr-1), respectively. The temperature sensitivity (Q 10) of R s (2.70±0.14) in the primary forest was significantly higher than that in the secondary forest (2.34±0.12), with the Q 10 values for respiration decreasing in the order of R NR> R s> R NL. These results show that the difference in litter respiration between primary and secondary forest caused the major difference in annual soil respiration efflux between these two forest types. In addition, the litter respiration is more sensitive to the soil temperature than the other soil respiration components.
    M. Noelia Barrios-Garcia, Mariano A. Rodriguez-Cabal, Jennifer A. Rudgers, Gregory M. Crutsinger
    2017, 10 (5): 800-807.
    Abstract ( 146 )   PDF   Save
    Aims While a growing number of studies have demonstrated the importance of intraspecific differences within plant species on associated arthropod communities, little is known regarding the relative strength of these effects compared to environmental factors. In this study, we examined whether intraspecific plant differences and nutrient fertilization interact to shape the arthropod community of a dominant coastal shrub, Baccharis pilularis (coyote bush).
    Methods We overlaid a fertilization treatment on a 12-year-old common garden experiment planted with erect and prostrate architectural morphs of Baccharis in California, USA. To collect the associated arthropod community, we vacuum sampled the crown of each Baccharis and identified individuals to species or morphospecies.
    Important findings We found that arthropod richness and abundance were 2- to 3-fold greater on prostrate Baccharis than on erect morphs, but observed no main effects of fertilizer addition on the overall arthropod communities. Predators responded as strongly as herbivores to plant morph, and both were unaffected by nutrient additions. Only the specialist stem galler, Gnorimoschema baccharisella, showed an interactive response to plant morph and fertilization. Nitrogen, phosphorous and potassium addition had opposite effects on the two morphs, increasing stem gall abundance by 50% on prostrate morphs, but reducing galling by 20% on erect morphs. The architectural complexity of prostrate morphs could be the driving mechanism of differences in arthropod assemblages. Overall, our results demonstrate that community-level consequences of intraspecific differences in plants are strong, rather than being context dependent, and are generally maintained under different resource environments. The growing number of studies showing strong genotype than nutrient effects on associated arthropod communities suggests that this might be a generalized pattern.
    Johannes Heinze, Sabine Gensch, Ewald Weber, Jasmin Joshi
    2017, 10 (5): 808-821.
    Abstract ( 185 )   PDF   Save
    Aims Plants directly and indirectly interact with many abiotic and biotic soil components. Research so far mostly focused on direct, individual abiotic or biotic effects on plant growth, but only few studies tested the indirect effects of abiotic soil factors on plant growth. Therefore, we investigated how abiotic soil conditions affect plant performance, via changes induced by soil biota.
    Methods In a full-factorial experiment, we grew the widespread grass Dactylis glomerata either with or without soil biota and investigated the impact of soil temperature, fertility and moisture on the soil biota effects on plant growth. We measured biomass production, root traits and colonization by arbuscular mycorrhizal fungi as well as microbial respiration.
    Important findings We found significant interaction effects between abiotic soil conditions and soil biota on plant growth for fertility, but especially for soil temperature, as an increase of 10°C significantly changed the soil biota effects on plant growth from positive to neutral. However, if tested individually, an increase in soil temperature and fertility per se positively affected plant biomass production, whereas soil biota per se did not affect overall plant growth, but both influenced root architecture. By affecting soil microbial activity and root architecture, soil temperature might influence both mutualistic and pathogenic interactions between plants and soil biota. Such soil temperature effects should be considered in soil feedback studies to ensure greater transferability of results from artificial and experimental conditions to natural environmental conditions.
    Fei Ren, Weimin Song, Litong Chen, Zhaorong Mi, Zhenhua Zhang, Wenyan Zhu, Huakun Zhou, Guangmin Cao, Jin-Sheng He
    2017, 10 (5): 822-830.
    Abstract ( 161 )   PDF   Save
    Aims Nitrogen (N)-fixing legumes, despite being highly phosphorus (P)-demanding, constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands. However, legume performance, including biomass, abundance and species richness, is expected to change, because anthropogenic activities have drastically increased soil N and P availability worldwide. We conducted a field experiment to assess the effects of N and P addition, alone and in combination, on legume performance in an alpine grassland, and identified and clarified the mechanisms underlying these changes.
    Methods A three year field experiment of N addition (10g N m ?2 year-1), P addition (5g P m ?2 year-1), and N + P combined addition (both N and P, same amounts as solo treatments) was conducted in an alpine grassland on the Tibetan Plateau in China from 2011 to 2013. Effects of nutrient addition were assessed at the community level (above-ground net primary production (ANPP), height and light intensity), functional group level (biomass, species richness, relative height, relative coverage and relative density of legumes) and species level (foliar N, P concentration of two legumes).
    Important findings Overall, adding N alone significantly increased ANPP by 20.82%, but adding P alone did not; whereas, addition of N and P together resulted in a large increase in ANPP (+37.03%) than addition of either alone, indicating potential co-limitation of alpine grasslands. In contrast, adding P alone significantly promoted legume performance as measured by 65.22% increase in biomass and 58.45% increase in relative abundance, while adding N alone reduced legume performance as measured by 39.54% decrease in biomass and 50.36% in relative abundance. Combining P and N addition did not mitigate the negative effect of N addition on legume performance and, surprisingly, suppressed legume biomass by 53.14% and relative abundance by 63.51%. N and P addition altered the balance of light competition between grasses and legumes as indicated by the changes in light levels, plant heights and litter accumulation. However, there were no obvious changes in legume species richness in response to N and P within our experimental timeframe. This study provides further evidence of the importance of P as a co-limiting nutrient in alpine grasslands, contrary to the traditional view that N limitation predominates in such regions. The contrasting effects of N and P addition on legume performance provide important insights into potential changes in legume performance in nutrient-limited grasslands following N and P enrichment under climate change, with implications for nutrient management in alpine grasslands.
    Hong-Wei Yu, Wei-Ming He
    2017, 10 (5): 831-838.
    Abstract ( 137 )   PDF   Save
    Aims Studying legacy effects (i.e. the indirect effect that persists for a period after casual factors cease) can provide novel insights into the role of ecological drivers. Leaf lifespan is among the key traits with multi-level functions. It is clear about the direct effects of water and nitrogen (N) amendment on leaf lifespan, but it remains unclear about their legacy effects on leaf lifespan and the associated mechanisms.
    Methods We performed a five-year field experiment with supplemental water and N, and quantified the legacy effects of field water and N addition on the leaf lifespan, length and growth rate of four dominant species, Agropyron cristatum, Cleistogenes squarrosa, Leymus chinensis and Stipa grandis in a temperate steppe.
    Important findings Across all the species, the legacies of water and N addition increased their leaf length and growth rate directly but decreased their leaf lifespan through direct and indirect pathways. Leaf lifespan was positively linked with leaf length but negatively associated to leaf growth rate. The legacy effect of water addition on leaf lifespan was greater than that of N addition. Field N addition induced soil acidification and eutrophication, as well as altered soil microbes, but only eutrophication had negative legacy effects on leaf lifespan. These findings provide substantial evidence that rainfall and N amendment have negative legacy effects on leaf lifespan, and also highlight that multiple mechanisms or pathways determine legacy effects. Additionally, our results suggest that field water and N manipulations may influence the other leaf traits and functions.
    Renato Gerdol, Roberta Marchesini, Paola Iacumin
    2017, 10 (5): 839-850.
    Abstract ( 121 )   PDF   Save
    Aims Altitude is often used as a proxy for ascertaining how warming affects plant growth and leaf level properties. However, we have a poor understanding of how the effects of altitude-related warming varies across geology. Therefore, this study examined the independent and interactive effects of altitude and geology and species on plant growth and foliar nutrient status.
    Methods We determined leaf growth rates and concentrations of major nutrients (nitrogen, N and phosphorus, P) in leaves of five species across two altitudinal gradients (1200–2200 m) in the Dolomites (south-eastern Alps, Italy). The two transects were located on carbonate bedrock and silicate bedrock, respectively. We also determined concentrations of inorganic and organic N and P forms in soils, and δ 15 N signature in leaves and soils.
    Important findings Foliar N concentrations were unrelated to bedrock geology. The negative foliar δ 15 N signature suggested that organic N was the primary source of N supply across the gradients. Foliar P concentrations were strongly affected by bedrock geology and their altitudinal patterns depended on the concentrations of organic and inorganic P forms in the soil. Phosphates and organic P appeared to be the main sources of P supply. Leaf growth rates increased with higher altitude on silicate bedrock and decreased with higher altitude on carbonate bedrock and presented a significant positive correlation with foliar N:P. In conclusion, bedrock geology interacted with altitude in controlling the foliar nutrient status mainly owing to availability of soil P and its effect on foliar nutrient stoichiometry.
    Andrew H. Lybbert, Samuel B. St. Clair
    2017, 10 (5): 851-858.
    Abstract ( 123 )   PDF   Save
    Aims Wildfire and ungulate herbivore pressure are increasing globally due to human activities, including arid ecosystems that are sensitive to disturbance, and are highly dependent on pollinator mutualisms. We evaluated how wildfire and ungulate herbivore pressure influence plant reproductive success and pollinator mutualisms.
    Methods We evaluated flower production, floral herbivory, pollinator visitation and fruit set of two Yucca species with highly specialized pollinator mutualisms (Yucca baccata and Yucca brevifolia) in unburned and burned landscapes created by fires that occurred in the Mojave Desert in 2005.
    Important findings Yucca baccata plants in burned landscapes had a greater proportion of flowering individuals than plants in unburned areas (23 versus 12%). All Y. brevifolia individuals in burned and unburned landscapes produced flowers. Sixty-four percent of Y. baccata inflorescences were removed due to herbivory by cattle in burned areas, compared to 51% in unburned locations. Forty-two percent of Y. brevifolia inflorescences on branches ≤2 m in height were removed in burned areas due to cattle herbivory compared to 39% in unburned locations. However, we did not observe any inflorescence removal on Y. brevifolia branches> 2 m where the majority of Y. brevifolia inflorescences are produced. Yucca moths, the only known pollinators of these two species, visited Y. brevifolia uniformly in burned and unburned areas but failed to visit Y. baccata altogether. Yucca brevifolia had strong fruit production, but not a single fruit was produced among the thousands of flowering Y. baccata plants surveyed. Floral herbivory and the loss of obligate pollinator mutualisms appear to be critical threats to the long-term viability of Y. baccata populations in this landscape. The reproductive resilience of Y. brevifolia and the maintenance of its pollinator populations appear to be due to its taller stature, which allows vertical escape of flowers from ungulate herbivores. Removal of livestock during the flowering period appears to be a critical first step to restoring Y. baccata's pollinator mutualisms and capacity for sexual reproduction.
    Polyanne A. Coelho, Paola Ferreira Santos, Eduardo de Paiva Paula, Deborah M. G. Apgaua, Bruno Gini Madeira, Gisele Cristina de Oliveira Menino, Yule Roberta Ferreira Nunes, Rubens M. Santos, David Y. P. Tng
    2017, 10 (5): 859-868.
    Abstract ( 172 )   PDF   Save
    Aims Understanding succession in tropical forest is an important aspect of vegetation science, but to date, successional processes in seasonally dry tropical forests (SDTFs) have received much less attention than evergreen humid tropical forests. We aim to fill this knowledge gap.
    Methods We investigated vegetation succession in SDTF areas consisting of three different successional stages (early, intermediate, late), and a SDTF-savanna ecotone in the municipal district of Juramento, north of Minas Gerais State, Brazil. Using twelve 400 m 2 plots in each area, we compared vegetation parameters and structural variables (absolute density and basal area) and examined the floristic composition of the tree component to find gradients of change.
    Important findings We found evidence of species turnover along a successional gradient, with the intermediate stage showing the highest species richness and diversity. This was accompanied with a significant increase in the number of tree individuals and basal area from the ?early to intermediate successional stage. However, the intermediate and late SDTF successional stages were more similar in structure and floristics. The ecotone was the most species rich and was similar to the intermediate SDTF and early successional stage in species richness and floristic composition respectively. These results will have implications for guiding SDTF management and recovery programs.
    Xabier Santiso, Rubén Retuerto
    2017, 10 (5): 869-881.
    Abstract ( 148 )   PDF   Save
    Aims The limited water supply in the Mediterranean Basin will be exacerbated in the immediate future as result of severe drought events. Thus, the study of the intraspecific variability in functional traits of plant species is important, because such variability modulates species' responses. Here, we aimed to analyse the variability in plasticity of physiological and structural traits of Arbutus unedo L. in response to water availability and to determine whether the levels of phenotypic plasticity varied in plants of different provenances.
    Methods We kept two sets of plants under contrasted water regimes (high water and low water) and calculated a phenotypic plasticity index to determine the plastic response to water stress. We compared the response among kind of traits and provenance. We also performed analysis of variance to assess the trait and provenance effect.
    Important findings We found that biomass and key physiological traits decrease under drought conditions, while the water use efficiency increased. Plasticity differed between groups of traits, being higher in structural and gas exchange parameters, but the provenance did not account for significant variation in plasticity. A. unedo has evolved a 'good saver' strategy, involving decreasing growth and water use—when this resource is unavailable—together with the dissipation of excess of radiation that it cannot process. The homogeneous response between provenances may be the result of a canalization event. This strategy, based on a high degree of plasticity, is a probable determining factor in the success of the species over its wide range of environmental conditions and will be critical to withstand the ongoing environmental changes.
IF: 1.780
5-year IF: 2.674
Wen-Hao Zhang
Bernhard Schmid
CN 10-1172/Q
ISSN 1752-9921(print)
ISSN 1752-993X(online)