Long‐term impact of legume‐based cropping with chemical and integrated fertilisation on viable weed seed density, diversity and community structure

Weed Research ◽  
2021 ◽  
Author(s):  
Chaitanya P. Nath ◽  
Kali K. Hazra ◽  
Chandra S. Praharaj ◽  
Ummed Singh ◽  
Sati S. Singh ◽  
...  
Keyword(s):  
Community Structure ◽  
Seed Density ◽  
Weed Seed ◽  
Long Term Impact

scholarly journals Effects of Reduced and Conventional Tillage on Weed Communities: Results of a Long-Term Experiment in Southwestern Spain

2019 ◽  
Vol 37 ◽  
Author(s):  
G. PARDO ◽  
A. CIRUJEDA ◽  
F. PEREA ◽  
A.M.C. VERDÚ ◽  
M.T. MAS ◽  
...  
Keyword(s):  
Diversity Index ◽  
Conventional Tillage ◽  
Seed Density ◽  
Weed Seed ◽  
Term Experiment ◽  
Weed Communities ◽  
Weed Diversity ◽  
Long Term Experiment ◽  
Seed Distribution

ABSTRACT: An important drawback in adopting minimum tillage (MT) and no-tillage (NT) techniques is the frequently observed weed shift promoting adapted species and achieving poorer weed control. These changes can be detected best with long-term experiments, and results might differ depending on soil characteristics and the local flora. The objectives of this work were to evaluate the effect of reduced tillage on weed seed distribution in the soil profile and to identify possible consequences on weed diversity on a long-term experiment maintained during 24 years in Seville (Spain) with three tillage systems: NT, MT and conventional tillage (CT) including moldboard plow on a vertisol. For this purpose, soil seedbanks at 0-8 cm and 8-16 cm depths were enumerated in autumn 2005 and in-field emerged plants in autumn 2005 and winter 2006. Shannon diversity index (H) and evenness (J’) were calculated for seedbank and aboveground weed communities. Total weed seed density was highest for NT and lowest for CT. Some big-seeded species, such as Chrozophora tinctorea L., showed highest seed density in CT. NT increased the relative density of Amaranthus blitoides S. Watson seeds in the seedbank and the abundance of emerged plants of Malva parviflora L., Anagallis arvensis L. and Picris echioides L. Overall, MT led to a less diverse seedbank in the 0-8 cm depth of soil than CT. The frequent drought-induced deep fractures in the expandable clay soil caused natural tillage, which probably resulted in fewer differences in weed seed and seedling densities among tillage treatments compared to what might be expected in other soil types.

scholarly journals Quantifying long-term evolution of intra-urban spatial interactions

2015 ◽  
Vol 12 (102) ◽  
pp. 20141089 ◽  
Author(s):  
Lijun Sun ◽  
Jian Gang Jin ◽  
Kay W. Axhausen ◽  
Der-Horng Lee ◽  
Manuel Cebrian
Keyword(s):  
Community Structure ◽  
Transport Cost ◽  
Spatial Interactions ◽  
Cross Sectional ◽  
Line Extension ◽  
Before And After ◽  
Spatial Reorganization ◽  
Long Term Impact ◽  
The Impact

Understanding the long-term impact that changes in a city's transportation infrastructure have on its spatial interactions remains a challenge. The difficulty arises from the fact that the real impact may not be revealed in static or aggregated mobility measures, as these are remarkably robust to perturbations. More generally, the lack of longitudinal, cross-sectional data demonstrating the evolution of spatial interactions at a meaningful urban scale also hinders us from evaluating the sensitivity of movement indicators, limiting our capacity to understand the evolution of urban mobility in depth. Using very large mobility records distributed over 3 years, we quantify the impact of the completion of a metro line extension: the Circle Line (CCL) in Singapore. We find that the commonly used movement indicators are almost identical before and after the project was completed. However, in comparing the temporal community structure across years, we do observe significant differences in the spatial reorganization of the affected geographical areas. The completion of CCL enables travellers to re-identify their desired destinations collectively with lower transport cost, making the community structure more consistent. These changes in locality are dynamic and characterized over short timescales, offering us a different approach to identify and analyse the long-term impact of new infrastructures on cities and their evolution dynamics.

The long-term impact of cefalexin on organic substrate degradation and microbial community structure in EGSB system

Chemosphere ◽  
2017 ◽  
Vol 184 ◽  
pp. 215-223 ◽  
Author(s):  
Ling-Wei Meng ◽  
Xiang-Kun Li ◽  
Shu-Tao Wang ◽  
Li-Li Liu ◽  
Kai-Li Ma ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Organic Substrate ◽  
Substrate Degradation ◽  
Long Term Impact

Crisis Phones - Suicide Prevention Versus Suggestion/Contagion Effects

Crisis ◽  
2015 ◽  
Vol 36 (3) ◽  
pp. 220-224 ◽  
Author(s):  
Steven Stack
Keyword(s):  
Suicide Prevention ◽  
Contagion Effects ◽  
Long Term Impact

Abstract. Background: There has been no systematic work on the short- or long-term impact of the installation of crisis phones on suicides from bridges. The present study addresses this issue. Method: Data refer to 219 suicides from 1954 through 2013 on the Skyway Bridge in St. Petersburg, Florida. Six crisis phones with signs were installed in July 1999. Results: In the first decade after installation, the phones were used by 27 suicidal persons and credited with preventing 26 or 2.6 suicides a year. However, the net suicide count increased from 48 in the 13 years before installation of phones to 106 the following 13 years or by 4.5 additional suicides/year (t =3.512, p < .001). Conclusion: Although the phones prevented some suicides, there was a net increase after installation. The findings are interpreted with reference to suggestion/contagion effects including the emergence of a controversial bridge suicide blog.

Long-Term Impact of Participation in the Adolescent Diversion Project

2009 ◽  
Author(s):  
Jenna L. Claes ◽  
Sean S. Hankins ◽  
J. K. Ford
Keyword(s):  
Long Term Impact
Sign in / Sign up

Export Citation Format

Share Document