Plant species' range type determines local responses to biotic interactions and land use

Carex pulicaris abundance is positively associated with soil acidity, rainfall and floristic diversity in the eastern distribution range

Carex pulicaris is considered an endangered species, and further losses are forecast under the influence of even moderate climate change. Local studies indicate that temporal declines in C. pulicaris abundance are positively correlated to decreases in precipitation and increases in air temperature. Determining ecological properties on larger scales than local ones can help develop effective protection programs for the species. We hypothesize that the local relationships observed between C. pulicaris abundance and precipitation, air temperature and soil properties will be confirmed in a spatially-oriented large-scale study performed in situ. Therefore, the present study takes a novel, large-scale integrated approach to (1) precisely characterize the ecological requirements of C. pulicaris within its eastern distribution range, and (2) determine the influence of its community type, soil properties and climatic conditions on its abundance. It was found that C. pulicaris is not a dominant or codominant species in the studied phytocoenoses in the eastern distribution range. Five natural vegetation groups including C. pulicaris, with significantly diverse species compositions, were resolved: well supported Estonian, Polish, Slovak and Radecz groups, and a weakly-supported Ambiguous group. The abundance of C. pulicaris was found to be positively correlated with the composition of the geographically-diversified plant communities and atmospheric precipitation, and to be also negatively associated with latitude and soil pH. Although the species is adapted to a relatively wide range of soil types, such adaptation requires appropriate substrate moisture level and light conditions. The species prefers moist organic and mineral soils and grows on both acid and neutral medium, characterized by a narrow C:N ratio, with various amounts of digestible total P, Mg and N, and low levels of digestible K. Climate change, manifested by reduced rainfall, may be one of the most important predictors negatively affecting the occurrence of C. pulicaris.

A case for associational resistance: Apparent support for the stress gradient hypothesis varies with study system

According to the stress gradient hypothesis (SGH), ecological interactions between organisms shift positively as environmental stress increases. In the case of associational resistance, habitat is modified to ameliorate stress, benefitting other organisms. The SGH is contentious due to conflicting evidence and theoretical perspectives, so we adopted a meta-analytic approach to determine if it is widely supported across a variety of contexts, including different kingdoms, ecosystems, habitats, interactions, stressors, and life history stages. We developed an extensive list of Boolean search criteria to search the published ecological literature and successfully detect studies that both directly tested the hypothesis, and those that were relevant but never mentioned it. We found that the SGH is well supported by studies that feature bacteria, plants, terrestrial ecosystems, interspecific negative interactions, adults, survival instead of growth or reproduction, and drought, fire, and nutrient stress. We conclude that the SGH is indeed a broadly relevant ecological hypothesis that is currently held back by cross-disciplinary communication barriers. More SGH research is needed beyond the scope of interspecific plant competition, and more SGH research should feature multifactor stress. There remains a need to account for positive interactions in scientific pursuits, such as associational resistance in tests of the SGH.

The impact of liquefaction disaster on farming systems at agriculture land based on technical and psychosocial perspectives

This research aims to determine the attitudes of the farmers whose lands are affected by liquefaction in Jono Oge, Central Sulawesi Province, The Republic of Indonesia. The methods used here were integrated survey and experimental design. The survey approach was intended to figure out the attitudes of the farmers viewpoints: (1) to return to their activities on the agricultural lands affected by liquefaction; (2) to consume their own agricultural products; and (3) of their willingness to be relocated. The experimental design approach was used to figure out the effectiveness of organic material input combined with the SP-36 fertilizer. The obtained results were analyzed using the Likert Scale, diversity test, correlational test, and regression test. The results showed that the farmers persevered farming on the lands affected by liquefaction (Index = 88.82%) yet refused to consume their own agricultural products with the reason that corpses remained buried beneath their lands (Index = 27.82%); and they also refused to be relocated (Index = 28.80%). The continued production suitability of the affected land was also investigated. Terrain profile identification results in Jono Oge showed the disaster impact was dominantly landslide as it still showed a clear characteristic horizon between the topsoil and the sub soil. This contrasts to terrain at Petobo, Central Sulawesi Province, where the high mix of the topsoil with the sub soil of agricultural land affected by liquefaction, prevented demarcation of the horizon. The land treatment of organic material and SP-36 fertilizer showed that the combined dose (M) of 40-kg ha-1 with P 300-kg ha-1 had the highest effect by changing the field pH from 5.7 to 6.41, increased the availability of P and increased the corncob indicator plant weight. Based on these indications, the lands affected by the liquefaction in Jono Oge can still be used as agricultural lands through restoration, from both social and technical aspects.