Plant Growth Forms Research Articles

The rhizosphere effect on soil gross nitrogen mineralization: A meta-analysis

Rhizosphere effects play crucial roles in determining soil carbon (C) and nitrogen (N) cycling. However, the rhizosphere effect on soil gross nitrogen (N) mineralization (Nmin) has not been quantitatively assessed on the global scale. Here we performed a meta-analysis of compiled data from 24 publications and 37 species to synthesize the rhizosphere effect on soil gross Nmin and its influencing factors. We found that the rhizosphere effect significantly enhanced soil gross Nmin by 81% on average. Such rhizosphere effect was significantly higher in woody species than in nonwoody species, and higher in ECM (ectomycorrhizal) associated species than in AM (arbuscular mycorrhizal) associated species. Moreover, the variations of the rhizosphere effect on soil gross Nmin were correlated with those on soil C mineralization, phenol oxidase activity and root biomass rather than with other plant (growth form and mycorrhizal association) and climatic (mean annual temperature and precipitation) factors. These results support the ‘microbial activation’ and ‘microbial N mining’ hypotheses of rhizosphere effects and indicate the coupling of soil C and gross N mineralization in the rhizosphere. Overall, these findings provide novel insights into the rhizosphere effect on soil gross Nmin among plant growth forms and mycorrhizal associations, and improve our mechanistic understanding of soil N dynamics in the rhizosphere.

Quantifying variations in browsing pressure caused by feral deer for a range of threatened ecological communities and plant growth forms

AbstractGlobally, high‐density populations of feral deer have been associated with a range of negative ecological consequences. Within Australia, limited quantitative research has assessed the impacts of deer, particularly in threatened ecological communities (TECs). Our study aimed to quantify the impact of feral deer on the herbivory of a range of woody plant species, non‐woody growth forms and TECs; and assess whether feral deer increase herbivory in TECs above background rates caused by native herbivores. We surveyed 356 transects across 89 sites representing eight TECs and collected herbivory data for woody and non‐woody plants. At each site, we recorded the presence or absence of deer sign and abundance of macropod pellets to account for variations in herbivory between groups of sympatric species. Generalised linear mixed models were developed to predict: (i) proportion of individual plants browsed (or grazed); and (ii) average browsing (or grazing) intensity for woody plant species and non‐woody plants. Controlling for macropod abundance, we found the average grazing intensity and proportion of non‐woody plants grazed was higher when deer were present compared to absent. Specifically, grazing pressure on rushes, cycads, sedges and grasses was significantly higher where deer were present. In contrast, we did not observe a significant impact of deer on woody plant species. The presence of deer resulted in higher grazing intensity in coastal saltmarsh, freshwater wetland, littoral rainforest and bangalay sand forest TECs. Although the deer population across our study region generally appears to be at low density compared to neighbouring regions, their presence is resulting in grazing pressure above that caused by native herbivores for a range of non‐woody plants. Our results contribute to a growing body of research about the ecological impacts of feral deer in Australia and can be used as a baseline for ongoing regional monitoring of deer impacts in TECs.

Habitat determines plant community responses to climate change in the High Arctic

Plant climate responses may depend on site-specific environmental context. Using fences and open-top chambers, we enhanced snow depth (creating Ambient, Medium, and Deep regimes) over an 11-year period and increased temperatures for two summers in dry heath and mesic meadow habitats on Svalbard, Norway. Comparison of plant growth form abundance and diversity responses in these two habitats showed that the response was more limited in the dry heath than in the mesic meadow. Common to both habitats was a decrease in shrub abundance and vascular plant species richness in the Deep snow regimes. Bryophyte abundance increased with enhanced snow cover in both habitats, but only up to a certain extent of snow depth in the meadow. However, for many growth forms, the effects of snow enhancement were habitat specific. In the mesic meadow, the abundance of forbs and bryophytes increased with snow enhancement, but the effect was stronger when combined with summer warming. The “bryofication” — that is, an increased abundance of bryophytes in response to snow enhancement and summer warming — also influenced overall plant diversity in the mesic meadow. Bryophytes are species-rich taxa and may respond differently than vascular plants to environmental change. We show that the inclusion of even the most common bryophytes in measures of diversity may determine overall plant diversity responses to environmental change in the Arctic.

Regional effects of plant diversity and biotic homogenization in urban greenspace – The case of university campuses across China

The human introduction and spread of species in urban greenspace may lead to an increase in the similarity of plant species composition between distant areas. Univervsity campuses are an important element of greenspace in many cities, but we know little about the extent to which such biotic homogenization of plant species can be detected across different regions and plant growth forms. Here, we collected plant species occurrence data from 253 Chinese university campuses in 130 cities to explore patterns and drivers of plant diversity and biotic homogenizations across different geographical regions and growth forms. We found that native species richness was positively correlated to campus area at the national scale, while non-native species richness was significantly associated with mean annual temperature, precipitation seasonality, campus area and campus age. We found limited support for homogenization caused by non-native plants in most regions. For growth forms, tree species exhibited significant biotic homogenization at the national scale, with weak or no effect for shrubs or herbs. Plant compositional similarity varied among regions, and eastern China always had the highest similarity in species composition with other regions. Combined effects of mean annual temperature and geographic distance overshadowed the roles of other predictors in shaping compositional dissimilarity in most regions. These findings suggest that multi-region settings and plant growth forms should be considered in urban biodiversity management, with special attention towards avoiding homogenization in trees. Increasing native species with local characteristics and considering region-specific environmental and socio-economic conditions are beneficial to mitigate biotic homogenization in urban greenspace.

Anatomical adaptations in aquatic and wetland dicot plants: Disentangling the environmental, morphological and evolutionary signals

Understanding how plants adjust their internal structures to withstand adverse environmental conditions is vital for predicting their responses to ongoing environmental change. Plants have repeatedly evolved small water transporting conduits and large storage parenchyma tissues to cope with anoxia, freezing- or drought‐induced damages. However, how these adaptations evolved in unrelated taxa across hydrological and thermal gradients, remains unclear. Here we show that stem anatomical variations in 212 European aquatic and wetland dicots are driven by thermal and hydrological constraints via control over plant size, growth form, and leaf traits, while phylogenetic constraints have only a weak effect. Phylogenetic comparative analyses controlling for confounding factors showed that both waterlogging (anoxia) and low-temperature promote smaller plants with reduced vessel conduits and limited lignification, but extended parenchyma and hence storage and tissue renewal capacity to secure resilience to biomass loss induced by running water or frost disturbances. Decreasing water depth and anoxia promote larger wetland plants with thick-walled libriform fibers, large vessels with simple perforation plates securing high hydraulic efficiency, and semi-ring porous xylem with wide earlywood vessels in spring and narrow latewood vessels in summer, providing both efficiency and safety in water transport. The aquatic environment promotes plants with a large cortex zone with photosynthetic chlorenchyma and starch-storing parenchyma cells along with extensive air spaces that provide aeration and buoyancy. Low temperatures promote short-stature forbs with smaller vessels, scalariform perforation plate, extended parenchyma, resulting in reduced embolism risk. Although most anatomical variation was explained by differences between aquatic and wet terrestrial growth forms, environmental gradients, plant size, and leaf properties exerted a significant control on plant tissue structures not confounded by phylogenetic inertia. Distinct habitats, spread across broad thermal and hydrological gradients, harbor unrelated species with different evolutionary histories that have converged to similar anatomical and hence morphological structures.

Plant functional traits along an old-field succession in the high tropical andes

The páramo, a high tropical Andean ecosystem, presents very distinct climatic, floristic and ecological features. Paramo plants have adapted to pronounced daily temperature fluctuations, freezing temperatures any night of the year, high incoming radiation and seasonal unfavorable water availability conditions. Long fallow agricultural systems are common in the páramo, permitting partial recuperation of the vegetation through a secondary succession. Different hypothesis related to plant traits (water relations and gas exchange characteristics or biomass allocation patterns) during succession have been proposed. Particular traits have been associated to the stages along successional gradients from early species (traits related to high resource acquisition abilities) to late species (traits linked to internal conservation of resources). Our purpose was to study plant functional responses of different herbaceous species in an old-field succession in the high tropical Andes. Plant traits (specific leaf area (SLA), maximum CO2 assimilation rates (Amax), leaf nitrogen content (Nleaf), leaf water relations and biomass allocation) were studied in grasses and forbs along different successional stages. Clear trends in SLA, Amax on a mass basis, Nleaf and aboveground/belowground biomass allocation were found along the successional gradient for grasses, while patterns were not as well-defined for forbs in the latter two traits. No patterns in leaf water relations characteristics were observed for either plant-growth forms. Strategies associated to plant traits significantly influence plant species dominance and community assembly during secondary succession in tropical alpine open environments like the páramos. Plant traits linked to rapid growth (SLA, Amax and Nleaf) dominate during early succession. In contrast to previous studies, drought resistance traits were not found to dominate in late succession stages for either grasses or forbs.

The convergence of species composition along the drawdown zone of the Three Gorges Dam Reservoir, China: implications for restoration.

Many rivers across the globe are regulated by dams, resulting in a strong alteration of the plant community composition of the drawdown zone. But, how these changes happen along the drawdown zone is less understood. In this study, a multivariate analysis was used to explore plant composition and similarity along the drawdown zone of the Three Gorges Dam Reservoir (TGDR), China. The dominant plant species, species richness, indicator species, and growth form were compared among the upstream, midstream, and downstream of the TGDR. Moreover, variation partitioning was used to determine the relative importance of environmental factors and spatial factors. Results showed that only a few species contributed the most to the community composition of the study area, and there was an extreme similarity in the plant community composition across the three different river segments. Furthermore, the results of the linear regression model demonstrated a steady declining trend in species richness along the drawdown zone, with the lowest species richness in the downstream segment. In addition, variation partitioning revealed 11% and 8% of the species composition change under environmental and spatial factors, respectively. Our results suggested that the dam impoundment led to the convergence of species composition along the drawdown zone of the TGDR, and environmental filtering and dispersal limitation played an imperative role in shaping species composition. The study highlighted the importance of restoration activities in overcoming the barriers of seed dispersal and seedling establishment in the degraded drawdown zone ecosystem of the TGDR.

Vegetation responses to 26 years of warming at Latnjajaure Field Station, northern Sweden

Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment. We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analyzed based on a seven-year Community-Level Interaction Program experiment. The communities had distinct soil moisture conditions, leading to community-specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs, and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.

The birth of modern rainforests

Paleoecology The origin of modern rainforests can be traced to the aftermath of the bolide impact at the end of the Cretaceous. Carvalho et al. used fossilized pollen and leaves to characterize the changes that took place in northern South American forests at this time (see the Perspective by Jacobs and Currano). They not only found changes in species composition but were also able to infer changes in forest structure. Extinctions were widespread, especially among gymnosperms. Angiosperm taxa came to dominate the forests over the 6 million years of recovery, when the flora began to resemble that of modern lowland neotropical forest. The leaf data also imply that the forest canopy evolved from relatively open to closed and layered, leading to increased vertical stratification and a greater diversity of plant growth forms. Science , this issue p. [63][1]; see also p. [28][2] [1]: /lookup/doi/10.1126/science.abf1969 [2]: /lookup/doi/10.1126/science.abh2086

Community‐level responses to increasing dryness vary with plant growth form across an extensive aridity gradient

AbstractAimPerennial plant communities are crucial for regulating ecological processes and maintaining ecosystem functions. Variation in community structure is driven by both biotic and abiotic factors, reflecting adaptation strategies of plant communities to various environments. Although much is known about the response of individual perennial plants to drier climates, empirical evidence of the community‐level responses to increasing dryness is limited.LocationEastern Australia; 1500 km gradient.TaxonPerennial plants.MethodsWe measured the abundance and size distribution (median, skewness and variance) of perennial plant communities from different growth forms (trees, shrubs and grasses), the spatial arrangement of trees in the overstorey and both biotic (competition) and abiotic (climate, soil properties) factors at 150 sites along an extensive aridity gradient from humid to arid areas. We used regression analyses and linear models to explore variation in community structure with increasing aridity and key driving factors for different perennial plant communities.ResultsVariation in community structure differed with growth form. As aridity increased, trees had wider canopies and were spatially aggregated, shrubs became miniaturised, but highly variable in size, and grasses comprised more larger individuals. Biotic and abiotic factors exerted different effects on different growth forms, with trees and shrubs consistently affected by competition and aridity, respectively, whereas grasses were weakly affected by aridity, summer rainfall and soil texture.Main conclusionsOur study highlights the idiosyncratic adaptation strategies used by trees, shrubs and grasses in response to drying climates at the community level through their effect on the size distribution or spatial aggregation. The structure of different perennial growth forms was influenced by different effects from either biotic (competition) or abiotic (climate, soil) factors. Under forecasted drier climates, canopy expansion and greater aggregation of trees might enhance resource sinks and shelter for diverse biota, potentially shielding plant communities against predicted aridification.

Fine root trait-function relationships affected by mycorrhizal type and climate

Root respiration is a critical function of root carbon cycling and accounts for a major component of the global carbon budget. However, the insufficient understanding of the global scaling relationships between root traits and respiration rate (Rr) impedes the accurate prediction of carbon effluxes from roots. Here, we analyzed a dataset of 138 species to unravel and quantify the effects of mycorrhizal type, climate, soil, and phylogenetic structure of species on fine root trait-function relationships. Four commonly measured traits were included: root nitrogen content (RNC), specific root length (SRL), root diameter, and root tissue density. We found that mycorrhizal type and climate affected the relationships between fine root traits and Rr. Specifically, the slopes of SRL-Rr and RNC-Rr relationships for ectomycorrhizal (EM) plants were significantly greater than those for arbuscular mycorrhizal (AM) plants, irrespective of the phylogenetic conservatism or plant growth forms. This finding suggested that EM plants consumed more carbon than AM plants for constructing root tissue structures. In a warmer environment, the SRL-Rr relationship was stronger while the RNC-Rr relationship was weaker, possibly because Rr was limited by enzyme activity at low temperature and by substrate supply at high temperature. Our results highlighted the importance of mycorrhizas in influencing the root trait-function relationships. Thus, incorporating mycorrhizal types into trait-based terrestrial biosphere models may help to more accurately predict the future carbon-climate change feedback.

Extending vegetation site data and ensemble models to predict patterns of foliage cover and species richness for plant functional groups

ContextEnsembles of artificial neural network models can be trained to predict the continuous characteristics of vegetation such as the foliage cover and species richness of different plant functional groups.ObjectivesOur first objective was to synthesise existing site-based observations of native plant species to quantify summed percentage foliage cover and species richness within four functional groups and in totality. Secondly, we generated spatially-explicit, continuous, landscape-scale models of these functional groups, accompanied by maps of the model residuals to show uncertainty.MethodsUsing a case study from New South Wales, Australia, we aggregated floristic observations from 6806 sites into four common plant growth forms (trees, shrubs, grasses and forbs) representing four different functional groups. We coupled these response data with spatially-complete surfaces describing environmental predictors and predictors that reflect landscape-scale disturbance. We predicted the distribution of foliage cover and species richness of these four plant functional groups over 1.5 million hectares. Importantly, we display spatially explicit model residuals so that end-users have a tangible and transparent means of assessing model uncertainty.ResultsModels of richness generally performed well (R2 0.43–0.63), whereas models of cover were more variable (R2 0.12–0.69). RMSD ranged from 1.42 (tree richness) to 29.86 (total native cover). MAE ranged from 1.0 (tree richness) to 20.73 (total native foliage cover).ConclusionsContinuous maps of vegetation attributes can add considerable value to existing maps and models of discrete vegetation classes and provide ecologically informative data to support better decisions across multiple spatial scales.

Divergent roles of environmental and spatial factors in shaping plant β-diversity of different growth forms in drylands

The biogeographic patterns and its drivers of plant diversity across drylands have been well documented, while the associated difference in the determinants of plant β-diversity between different growth forms remain unclear. Here, we selected 68 plots from a typical dryland region of Northwest China to explore how and to what extent different environmental and spatial factors influence plant β-diversity of different growth forms. The results showed that environmental and spatial factors were significantly correlated with whole community, shrub and herb β-diversity (P < 0.001), and the combinations of soil, climate, topography, and spatial factors explained approximately 24, 10, and 20% of the variation in whole community, shrub and herb β-diversity, indicating that niche and neutral processes work together to regulate plant β-diversity in drylands of Northwest China. However, the relative contribution of environmental filtering and spatial processes varid between shrub and herb layers, where shrub β-diversity was predominantly determined by spatial processes, but herb β-diversity was largely determined by environmental filtering. Taken together, these findings provide an important empirical evidence that niche processes may not always be dominant processes of community assembly, even in harsh environments of drylands. Future research that focuses on the comparisons among different plant growth forms would likely shed new insights into mechanisms of community assembly under climate change.

Effects of host plant growth form on dropping behaviour in leaf beetles

Abstract Many leaf-eating insects drop from their host plants to escape predators. However, they must return to the leaves of the host plant after dropping, which represents a cost associated with this behaviour. In woody plants, the positioning of leaves is generally higher than that of herbaceous plants, which suggests that dropping from woody plants might be costlier for leaf-eating insects than dropping from herbaceous plants. Therefore, we predicted that dropping behaviour would be observed less frequently in insects that feed on woody plant leaves than in those that feed on herbaceous plant leaves. To test this prediction, we investigated dropping behaviour experimentally in larvae (23 species) and adults (112 species) of leaf beetles (Coleoptera: Chrysomelidae) on their host plants (86 species of 44 families) in field conditions. Larvae on woody plants exhibited dropping behaviour less frequently than those on herbaceous plants. However, this pattern was not detected in adults. Thus, host plant growth form might affect the evolution of dropping behaviour in leaf beetle larvae, but not in winged adults, perhaps owing to their higher mobility.

Decades of Recovery From Sheep Grazing Reveal No Effects on Plant Diversity Patterns Within Icelandic Tundra Landscapes

Tundra plant communities are often shaped by topography. Contrasting wind exposure, slopes of different inclination and landforms of different curvature affect habitat conditions and shape plant diversity patterns. The majority of tundra is also grazed by ungulates, which may alter topographically induced plant diversity patterns, but such effects may depend on the spatial scales of assessments. Here we ask whether topographically induced patterns of within (alpha) and between (beta) plant community diversity are different in contrasting grazing regimes. We studied plant communities within tundra landscapes that were located in the North and Northwest of Iceland. Half of the studied landscapes were grazed by sheep, whereas the other half was currently un-grazed and recovering for several decades (up to 60 years).Alphaandbetadiversity were assessed on explicitly defined, nested spatial scales, which were determined by topographical units. Although we contrasted currently grazed vegetation to vegetation that witnessed several decades of grazing recovery, we found no statistically significant differences in plant diversity patterns. We relate these findings to the low resilience of our study system toward grazing disturbances, which has important implications for management practices in the tundra. Effects of topography on species richness were only found for specific spatial scales of analyses. Species rich topographical units were associated with relatively large biomass of plant growth forms that promote nutrient availability and potential plant productivity in the tundra, such as forbs. This suggests that biomass of such plant growth forms within habitats can be a useful proxy of potential plant productivity and may predict spatial patterns of plant species richness in tundra.

Host functional traits affect plant responses to pathogen stress: A meta-analysis

Pathogens impose major biotic stresses on plant growth and development. A meta-analysis of 73 articles and 301 case studies was conducted to investigate whether plant functional traits affect plant responses to pathogen stress. Plant lifespan, herbaceous plant growth form, and N-fixing ability were found to be general determinants of plant growth following pathogen inoculation. Plant carbon fixation pathways and mycorrhizal association ability had inconsistent effects on plants growth following pathogen inoculation. Specifically, we found long-lived plants were less affected by pathogen inoculation than short-lived plants. The growth of forbs relative to grasses was more reduced by pathogen inoculation. The growth of non-N-fixing species relative to N-fixing species was less reduced by pathogen inoculation. Pathogen inoculation did not have significantly different effects on species with different carbon fixation pathways or different capacities for mycorrhizal associations. Our findings highlight the importance of plant functional traits in the responses of host plants to pathogen stress.

生长型分类方案不同导致森林生态系统植物功能性状的统计偏差

PDF HTML阅读 XML下载 导出引用 引用提醒 生长型分类方案不同导致森林生态系统植物功能性状的统计偏差 DOI: 10.5846/stxb202002010188 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31870462）；浙江省"万人计划"（2019R52014）；浙江师范大学重点建设项目（2017PT009， 2017XM023） Statistical bias of plant functional traits in forest ecosystems caused by different classifications of growth form Author: Affiliation: Fund Project: g Province (2019R52014), and the Key Program of Zhejiang Normal University (2017PT009, 2017XM023). 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:将植物划分为不同的生长型来统计植物功能性状特征，是当前植物性状研究中常用的方法；但生长型分类方案的不同很可能造成植物功能性状统计分析的偏差，对此偏差的评估却尚未见报道。根据植物志描述及野外调查实际情况，将生长型划分为3种不同的分类方案：分类1：根据植物志信息划分为传统意义的乔木和灌木；分类2：根据树高和胸径划分乔木、小乔木和灌木；分类3：仅根据树高划分乔木层与灌木层的乔木和灌木。以东部亚热带常绿阔叶林区域的浙江金华北山35种优势阔叶木本植物的枝叶性状为研究对象，比较不同生长型分类对植物枝叶性状统计数据的影响。结果表明：（1）与传统的分类1相比，分类2对乔木植物枝叶性状影响的显著程度要高于分类3，而对灌木植物枝叶性状的影响程度低于分类3；但不同生长型分类方案中乔木和灌木的枝叶性状总体差异不显著。而与分类2小乔木相比，分类1以及分类2内部的乔木和灌木生长型的性状与分类2小乔木差异非常明显；（2）将不同生长型植物再划分为不同生活型后，不同生长型分类方案对性状统计的影响增大。无论是常绿还是落叶生活型的小乔木，其与不同生活型乔木和灌木的性状差异仍然显著。可见，不同的生长型分类方案可造成植物功能性状统计的差异；把小乔木植物这一功能类群划分出来，能更好地反映森林生态系统性状特征的差异性。 Abstract:In current research of plant functional traits, classifying plants into different growth forms to statistically analyze features of plant functional traits is a common approach. Different classifications of growth form, however, may lead to statistical bias of plant trait values, and such bias has not been evaluated. In this paper we investigate how different classifications of growth form influence the calculation of plant functional traits. We classified the growth form of 35 dominant woody plants in eastern subtropical evergreen broadleaved forest region in Beishan Mountain of Jinhua, Zhejiang Province into three schemes according to the Flora of China and actual situation in filed investigation: the classification 1, traditional tree and shrub described in the floras; classification 2, trees, small trees and shrubs based on height and diameter in breast height; and classification 3, trees and shrubs of tree layer and shrub layer according to height only. The statistical bias of plant leaf and twig traits under three classifications of growth form was analyzed and compared. The results showed that: (1) compared with the traditional classification 1, classification 2 had a significant influence on twig and leaf traits of trees than classification 3, while the influence on twig and leaf traits of shrubs was lower than classification 3. However, there was no significant difference of tree and shrub traits in different growth classification schemes. Compared with small trees in classification 2, leaf and twig traits of trees and shrubs in classification 1 and even within the classification 2 were significantly different to those of small trees in classification 2; (2) After subdividing different growth forms into different life forms, the impact of different growth form classification schemes on trait statistics increased. However, leaf and twig traits of both evergreen and deciduous small trees were still significantly different from those of trees and shrubs in different life forms. In general, different classification schemes of plant growth forms can result in the statistical bias of plant functional traits. Separating the small tree from the tree and shrub functional groups could better reflect the differences of plant functional traits in forest ecosystems. 参考文献 相似文献 引证文献

Post‐fire changes in plant growth form composition and diversity in Andean páramo grassland

AbstractQuestionsFire suppression policies have been widely adopted in the páramo grasslands of the northern Andes to protect their biodiversity and ecosystem services. Páramos have been regularly burned for many years, and it is not clear how páramo vegetation will respond to significant changes in their fire regimes. This study investigates differences in plant growth form composition, light levels and soil temperatures in páramo plots representing a range of recovery times since the last fire.LocationReserva Ecológica El Ángel and La Bretaña Nature Reserve, Carchi, Northern Ecuador.MethodsWe assessed the frequency of ten páramo growth forms, vegetation height, soil temperature, and light intensity in fifteen fire sites with historical records of fire (&lt;1–15 years since fire), and one recently unburned site (at least 40 years since fire). A chronosequence of sites was used to assess potential changes in plant community composition in post‐fire succession of páramo.ResultsThe recovery of páramo vegetation after fire comprised three phases: initial recruitment with high growth form diversity, followed by reduced diversity, light and soil temperatures in dense tussock vegetation, and ultimately canopy height stratification with a return of diversity. All but one of the plant growth forms were represented in each of the three phases, and the changes reflected differences in relative abundance.ConclusionsPost‐fire páramo succession is characterised by clear shifts in the relative abundance of plant growth forms, ending with (co‐)dominance of upright shrubs. The long‐term consequences of such shifts for biodiversity and ecosystem function, given the widespread adoption of fire suppression policies in the páramo, need careful, evidence‐based consideration.

Heritability Paterns of Some Agro-Botanical Characters Related to Yield and Drought Tolerance in Two Landraces of Rice

AbstractTwo landraces of rice, AWGUII-04 and IJ-124, were characterised and assessed for phenotypic variability, heritability, genetic advance and modes of inheritance of some primary yield and drought-tolerance traits. The target traits for yield were a percentage of filled spikelets, plant form, tillering, and for drought tolerance, leaf rolling, ratooning and maturity. This study was carried out to help both breeders and farmers make a wise choice when carrying out hybridisation and on the field. Hybridisation produced three F1 hybrids that were advanced to F2 generation. Quantitative and qualitative vegetative and reproductive data were taken from each F2 population. The results obtained showed high heritability (62–100%) in all the thirty-eight vegetative and reproductive traits. The genetic advance was high (&gt; 20%) in all the target traits except for leaf rolling. The traits segregated in the following ratio: plant growth form – 9:6:1; the percentage of filled spikelets – 13:3; ratooning – 3:1; maturity – 15:1; the number of tillers – 15:1 and leaf rolling – 15:1. The high heritability of the above traits makes them highly dependable for rice crop improvement.

Changes of leaf functional traits in karst rocky desertification ecological environment and the driving factors

Karst rocky desertification (KRD), a degraded land form, has seriously damaged the balance and stability of the ecosystem. Plant functional traits reflect the response and adaptation of plants to the growth environment. However, little is known about the effects of ecological environment of KRD on plant functional traits. To explore plant ecological strategies and driving factors in ecological environment of KRD, the plants in three study areas of rocky desertification of South China Karst were selected as the study objects. The relationships between the leaf functional traits and plant characteristic (growth form) and environmental factors (climate, soil, lithology, landform, growth form and degree of KRD) were statistically analyzed. The results show that: As the transition of constructive species from herbs and liana to arbors, leaf thickness (LT), leaf area (LA) and leaf carbon content (LCC) showed an increasing trend, while specific leaf area (SLA), transpiration rate (Tr) and leaf phosphorus content (LPC) showed a gradually decreasing trend. After feature extraction by PCA, the different growth forms of plants were divided into three types: quick-gain type (herb and liana); slow-gain type (arbor); transitional type (shrub). The plant ecological strategies of different ecological environments of KRD are also different. The plants in the moderate-intense KRD area belong to the quick-gain type, while those in the non-potential KRD area belong to the slow-gain type. Variance partitioning showed that plant characteristic and environmental factors explained the change of leaf functional traits by 5% and 31%, respectively. Our study shows that environmental factors contribute more to the shaping of leaf functional traits than plant characteristic in KRD area. Among the environmental factors, average annual temperature, average annual precipitation, pH and degree of KRD are the main influencing factors for the change of leaf functional traits in ecological environment of KRD.