Negative effects of fertilization on grassland species richness are stronger when tall clonal species are present

2017 ◽  
Vol 52 (3-4) ◽  
pp. 401-409 ◽  
Author(s):  
Katherine L. Gross ◽  
Gary G. Mittelbach
Keyword(s):  
Species Richness ◽  
Negative Effects ◽  
Grassland Species ◽  
Clonal Species

scholarly journals Intraspecific trait variation drives grassland species richness and productivity under changing precipitation

Ecosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Meifeng Deng ◽  
Weixing Liu ◽  
Ping Li ◽  
Lin Jiang ◽  
Shaopeng Li ◽  
...  
Keyword(s):  
Species Richness ◽  
Trait Variation ◽  
Grassland Species ◽  
Intraspecific Trait Variation

scholarly journals Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1726
Author(s):  
Nasr H. Gomaa ◽  
Ahmad K. Hegazy ◽  
Arafat Abdel Hamed Abdel Latef
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Stress Gradient ◽  
Growing Season ◽  
Annual Species ◽  
Negative Effects ◽  
Growing Seasons ◽  
Dry Seasons ◽  
The Impact ◽  
Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

scholarly journals Potential and Limitations of Grasslands α-Diversity Prediction Using Fine-Scale Hyperspectral Imagery

2021 ◽  
Vol 13 (14) ◽  
pp. 2649
Author(s):  
Hafiz Ali Imran ◽  
Damiano Gianelle ◽  
Michele Scotton ◽  
Duccio Rocchini ◽  
Michele Dalponte ◽  
...  
Keyword(s):  
Species Richness ◽  
Well Being ◽  
Hyperspectral Data ◽  
Hyperspectral Images ◽  
Grassland Species ◽  
Biodiversity Indices ◽  
Grassland Ecosystems ◽  
Natural Grasslands ◽  
Α Diversity ◽  
Diversity Metrics

Plant biodiversity is an important feature of grassland ecosystems, as it is related to the provision of many ecosystem services crucial for the human economy and well-being. Given the importance of grasslands, research has been carried out in recent years on the potential to monitor them with novel remote sensing techniques. In this study, the optical diversity (also called spectral diversity) approach was adopted to check the potential of using high-resolution hyperspectral images to estimate α-diversity in grassland ecosystems. In 2018 and 2019, grassland species composition was surveyed and canopy hyperspectral data were acquired at two grassland sites: Monte Bondone (IT-MBo; species-rich semi-natural grasslands) and an experimental farm of the University of Padova, Legnaro, Padua, Italy (IT-PD; artificially established grassland plots with a species-poor mixture). The relationship between biodiversity (species richness, Shannon’s, species evenness, and Simpson’s indices) and optical diversity metrics (coefficient of variation-CV and standard deviation-SD) was not consistent across the investigated grassland plant communities. Species richness could be estimated by optical diversity metrics with an R = 0.87 at the IT-PD species-poor site. In the more complex and species-rich grasslands at IT-MBo, the estimation of biodiversity indices was more difficult and the optical diversity metrics failed to estimate biodiversity as accurately as in IT-PD probably due to the higher number of species and the strong canopy spatial heterogeneity. Therefore, the results of the study confirmed the ability of spectral proxies to detect grassland α-diversity in man-made grassland ecosystems but highlighted the limitations of the spectral diversity approach to estimate biodiversity when natural grasslands are observed. Nevertheless, at IT-MBo, the optical diversity metric SD calculated from post-processed hyperspectral images and transformed spectra showed, in the red part of the spectrum, a significant correlation (up to R = 0.56, p = 0.004) with biodiversity indices. Spatial resampling highlighted that for the IT-PD sward the optimal optical pixel size was 1 cm, while for the IT-MBo natural grassland it was 1 mm. The random pixel extraction did not improve the performance of the optical diversity metrics at both study sites. Further research is needed to fully understand the links between α-diversity and spectral and biochemical heterogeneity in complex heterogeneous ecosystems, and to assess whether the optical diversity approach can be adopted at the spatial scale to detect β-diversity. Such insights will provide more robust information on the mechanisms linking grassland diversity and optical heterogeneity.

scholarly journals Low effect on open-farmland birds of young afforestations in heterogeneous Mediterranean croplands

2014 ◽  
Author(s):  
Juan S. Sánchez-Oliver ◽  
José M. Rey Benayas ◽  
Luis M. L.M. Carrascal
Keyword(s):  
Species Richness ◽  
Bird Species ◽  
Agricultural Landscapes ◽  
Tree Plantations ◽  
Conservation Value ◽  
Farmland Birds ◽  
Negative Effects ◽  
Bird Species Richness ◽  
Positive Effects ◽  
The One

Afforestation programs such as the one promoted by the EU Common Agricultural Policy have spread tree plantations on former cropland. These afforestations attract generalist forest and ubiquitous species but may cause severe damage to open habitat species, especially birds of high conservation value. We investigated the effects of young (< 20 yr) tree plantations dominated by pine P. halepensis on bird communities inhabiting the adjacent open farmland habitat in central Spain. We hypothesize that pine plantations with larger surface, and areas at shorter distances from plantations, would result in lower bird species richness and conservation value of open farmland birds. Regression models controlling for the influence of land use types around plantations revealed significant positive effects of distance to pine plantation edge on community species richness in winter, and negative effects on an index of conservation concern (SPEC) during the breeding season. However, plantation area did not have any effect on species richness or community conservation value. Our results indicate that pine afforestation of Mediterranean cropland in heterogeneous agricultural landscapes has an overall low detrimental effect on bird species that are characteristic of open farmland habitat.

scholarly journals Anti-predator defence and the complexity–stability relationship of food webs

2007 ◽  
Vol 274 (1618) ◽  
pp. 1617-1624 ◽  
Author(s):  
Michio Kondoh
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Food Webs ◽  
Community Level ◽  
Negative Effects ◽  
Food Web Structure ◽  
Wide Range ◽  
The Stability ◽  
Food Web Complexity ◽  
Predator Defence

The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey–predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity–stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance–stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance–stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.

REALISTICALLY LOW SPECIES EVENNESS DOES NOT ALTER GRASSLAND SPECIES-RICHNESS–PRODUCTIVITY RELATIONSHIPS

Ecology ◽  
2004 ◽  
Vol 85 (10) ◽  
pp. 2693-2700 ◽  
Author(s):  
Brian J. Wilsey ◽  
H. Wayne Polley
Keyword(s):  
Species Richness ◽  
Species Evenness ◽  
Grassland Species

scholarly journals The Habitat Amount Hypothesis implies negative effects of habitat fragmentation on species richness and occurrence

2020 ◽  
Author(s):  
Santiago Saura
Keyword(s):  
Species Richness ◽  
Habitat Fragmentation ◽  
Spatial Configuration ◽  
Spatial Scales ◽  
Conservation Strategies ◽  
Negative Effects ◽  
Habitat Amount ◽  
Habitat Configuration ◽  
Habitat Amount Hypothesis ◽  
Individual Site

AbstractThe Habitat Amount Hypothesis (HAH) predicts that species richness, abundance or occurrence in a habitat site increases with the amount of habitat in the ‘local landscape’ defined by an appropriate distance around the site, with no distinct effects of the size of the habitat patch in which the site is located. It has been stated that a consequence of the HAH, if supported, would be that it is unnecessary to consider habitat configuration to predict or manage biodiversity patterns, and that conservation strategies should focus on habitat amount regardless of fragmentation. Here, I assume that the HAH holds and apply the HAH predictions to all habitat sites over entire landscapes that have the same amount of habitat but differ in habitat configuration. By doing so, I show that the HAH actually implies clearly negative effects of habitat fragmentation, and of other spatial configuration changes, on species richness, abundance or occurrence in all or many of the habitat sites in the landscape, and that these habitat configuration effects are distinct from those of habitat amount in the landscape. I further show that, contrary to current interpretations, the HAH is compatible with a steeper slope of the species-area relationship for fragmented than for continuous habitat, and with higher species richness or abundance for a single large patch than for several small patches with the same total area (SLOSS). This suggests the need to revise the ways in which the HAH has been interpreted and can be actually tested. The misinterpretation of the HAH has arisen from confounding and overlooking the differences in the spatial scales involved: the individual habitat site at which the HAH gives predictions, the local landscape around an individual site, and the landscapes or regions (with multiple habitat sites and different local landscapes) that need to be analysed and managed. The HAH has been erroneously viewed as negating or diminishing the relevance of fragmentation effects, while it actually supports the importance of habitat configuration for biodiversity. I conclude that, even in the cases where the HAH holds, habitat fragmentation and configuration are important for understanding and managing species distributions in the landscape.

scholarly journals Unexpected effects of pigeon-peas (Cajanus cajan) in the restoration of rupestrian fields

2011 ◽  
Vol 29 (4) ◽  
pp. 717-723 ◽  
Author(s):  
R.R Hilário ◽  
S.A.B Castro ◽  
F.T.O Ker ◽  
G Fernandes
Keyword(s):  
Species Richness ◽  
Cajanus Cajan ◽  
Biosphere Reserve ◽  
Plant Species Richness ◽  
Superficial Layer ◽  
Exchange Capacity ◽  
Individual Plant ◽  
Native Plant ◽  
Negative Effects ◽  
Rupestrian Fields

Several degraded areas can be found along the Highway MG-010 that crosses the Espinhaço Mountain Biosphere Reserve in the Brazilian state of Minas Gerais. Restoration by planting the legume Cajanus cajan was implemented in some of these areas. The present study compares plant species richness, diversity, abundance, equitability, similarity, and soil composition between restored and non-restored areas, in an attempt to evaluate the effectiveness of the use of C. cajan in the restoration process in the mountain environment. Each treatment (restored and non-restored) had four sampling areas, each with three 300 m² plots. We counted and identified every individual plant found within these plots. We also collected soil from the superficial layer (0-10 cm) of each sampling area in both treatments. The areas where C. cajan was planted revealed lower species richness, diversity, and plant abundance. The soil of these areas also contained higher levels of Phosphorus and Magnesium. Plant equitability and similarity between plots and other soil components (pH, Nitrogen, Aluminum, Calcium, Potassium, H+Al, sum of bases - SB, cation exchange capacity - CTC, base saturation - V%, aluminum saturation - M%) did not differ between the two treatments. Contrary to the expectations, soil enhancement in the quartzitic soil poor in nutrients in the rupestrian fields can facilitate the invasion by exotic plants, which are not adapted to the lack of nutrients. As it appears, the use of C. cajan in restoration projects represents a mistake and future restoration plans should avoid the use of exotic species, given that they may cause negative effects on the native plant community, as demonstrated here in the rupestrian fields.

Effect of summer livestock grazing on plant species richness and composition in the Himalayan rangelands

2015 ◽  
Vol 37 (3) ◽  
pp. 309 ◽  
Author(s):  
Suman Aryal ◽  
Geoff Cockfield ◽  
Tek Narayan Maraseni
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
National Park ◽  
Plant Species Richness ◽  
Livestock Grazing ◽  
Environmental Data ◽  
Negative Effects ◽  
Conservation Area ◽  
Α Diversity ◽  
Study Sites

Grazing systems in the high Himalayas are changing in response to socioeconomic factors and policy decisions. As well as effects on livelihood of herders, such changes may have significant impacts on plant species richness and composition. The objectives of this study were to explore how plant species richness and composition respond to livestock grazing in the high Himalayan rangelands. The study was conducted in three mountainous Protected Areas of Nepal viz. Sagarmatha (Mt Everest) National Park, Gaurishankar Conservation Area and Khaptad National Park. Species and environmental data were collected along perpendicular transects outwards from goths (semi-permanent stopping and camping points). It was found that the distance from goths generally represents a grazing disturbance gradient. The core areas near goths had low species richness per plot (α-diversity) where nitrophilous and grazing-tolerant species were commonly found. However, the highest species richness, total numbers of species and occurrences of rare species at mid- and farther distances from goths within 800 m suggest that negative effects of summer livestock grazing were small and confined to limited areas near goths. Altitude, soil moisture content, percentage shrub cover and distance from goths were the variables significantly correlated with species composition, although the relative importance of these factors varied across study sites. This research can be used to inform decision-making about seasonal livestock grazing in the Himalayan rangelands, which should incorporate both ecological as well as socioeconomic considerations.

scholarly journals Are Plant Species’ Richness and Diversity Influenced by Fragmentation at a Microscale?

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jesús Aguirre-Gutiérrez
Keyword(s):  
Species Richness ◽  
Forest Fragmentation ◽  
Vegetation Type ◽  
Plant Species Richness ◽  
Medium Size ◽  
Negative Effects ◽  
Forest Patches ◽  
Species Richness And Diversity ◽  
Short And Long Term

It is argued that forest fragmentation has negative effects on biodiversity at the short and long term; however, these effects might be dependent on the specific vegetation of the study area and its intrinsic characteristics. The processes leading to fragmentation are very diverse and many of them have anthropogenic causes as logging actions and clearings for agricultural fields. Furthermore, it is thought that scale plays an important role in the expected effects of fragmentation on biodiversity. In this study the effect of forest fragmentation and its impact on the woody plants species, richness and diversity are analysed considering three vegetation types in a poorly studied and difficult access biodiversity hotspot in northern Mexico. The results show that the effects of fragmentation are dependent on the vegetation type and that these are not strongly related to the species richness, and diversity in a microscale (100 m2). Fragmentation effects on biodiversity must be analysed in a broad scale, considering the fragment as a whole. Furthermore, conservation priority should be given to the larger fragments, which could potentially maintain a higher portion of biodiversity. Management should also be focused on increasing the connectivity between these big and medium size forest patches.

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