Species densities, assembly order, and competence jointly determine the diversity-disease relationship.

Since species vary in abundance and host competence (i.e., ability to get infected and transmit a pathogen), changes in species composition caused by biodiversity loss impacts disease dynamics. Forecasting effects of species composition on disease depends on community (dis)assembly, processes determining how species are added to (or lost from) communities. We simulated community assembly by planting mesocosms, nested along a richness gradient, and tested how relationships between richness, species assembly order, and overall density affect disease risk. Mesocosms with up to six crop species of varying competence were inoculated with a soilborne fungal pathogen, Rhizoctonia solani. Disease was measured as species-level prevalence, community-level prevalence, and total number of diseased plants. Regardless of metric, richness limited disease when species assembly order negatively correlated with competence and total density remained unchanged with richness. When density increased with richness or species assembled randomly, richness primarily correlated positively or weakly with disease. Our results align with theoretical expectations and represent the first empirical study to test the influence of species densities, assembly order, and competence on diversity-disease relationships.

Partial least squares for efficient models of fecal indicator bacteria on Great Lakes beaches.

At public beaches, it is now common to mitigate the impact of water-borne pathogens by posting a swimmer's advisory when the concentration of fecal indicator bacteria (FIB) exceeds an action threshold. Since culturing the bacteria delays public notification when dangerous conditions exist, regression models are sometimes used to predict the FIB concentration based on readily-available environmental measurements. It is hard to know which environmental parameters are relevant to predicting FIB concentration, and the parameters are usually correlated, which can hurt the predictive power of a regression model. Here the method of partial least squares (PLS) is introduced to automate the regression modeling process. Model selection is reduced to the process of setting a tuning parameter to control the decision threshold that separates predicted exceedances of the standard from predicted non-exceedances. The method is validated by application to four Great Lakes beaches during the summer of 2010. Performance of the PLS models compares favorably to that of the existing state-of-the-art regression models at these four sites.

Evaluating the performance of volunteers in mapping invasive plants in public conservation lands.

Citizen science programs are touted as useful tools for engaging the public in science and for collecting important data for scientists and resource managers. To accomplish the latter, it must be shown that data collected by volunteers is sufficiently accurate and reliable. We engaged 119 volunteers over three years to map and estimate abundance of invasive plants in New York and New Jersey parklands. We tested their accuracy via collected pressed samples and by subsampling their transect points. We also compared the performances of volunteers and botanical experts. Our results support the notion that volunteer participation can enhance the data generated by scientists alone. We found that the quality of data collected might be affected by the environment in which the data are collected. We suggest that giving consideration to how people learn can not only help to achieve educational goals but can also help to produce more data to be used in scientific study.

Knowledge gain and behavioral change in citizen-science programs.

Citizen-science programs are often touted as useful for advancing conservation literacy, scientific knowledge, and increasing scientific-reasoning skills among the public. Guidelines for collaboration among scientists and the public are lacking and the extent to which these citizen-science initiatives change behavior is relatively unstudied. Over two years, we studied 82 participants in a three-day program that included education about non-native invasive plants and collection of data on the occurrence of those plants. Volunteers were given background knowledge about invasive plant ecology and trained on a specific protocol for collecting invasive plant data. They then collected data and later gathered as a group to analyze data and discuss responsible environmental behavior with respect to invasive plants. We tested whether participants without experience in plant identification and with little knowledge of invasive plants increased their knowledge of invasive species ecology, participation increased knowledge of scientific methods, and participation affected behavior. Knowledge of invasive plants increased on average 24%, but participation was insufficient to increase understanding of how scientific research is conducted. Participants reported increased ability to recognize invasive plants and increased awareness of effects of invasive plants on the environment, but this translated into little change in behavior regarding invasive plants. Potential conflicts between scientific goals, educational goals, and the motivation of participants must be considered during program design.

Resumen: Los programas de ciencia-ciudadana a menudo son vendidos como útiles para que el público avance en sus conocimientos sobre conservación, en su conocimiento científico y en el incremento de las habilidades de razonamiento científico. No existen directrices para la colaboración entre científicos y el público y casi no se ha estudiado el grado en que estas iniciativas ciudadanos-ciencia cambian el comportamiento. Durante dos años estudiamos a 82 participantes en un programa de 3 días que incluía educación sobre plantas invasoras no nativas y la recolección de datos sobre la ocurrencia de estas plantas. A los voluntarios se les proporcionó conocimiento básico sobre la ecología de plantas invasoras y fueron entrenados en un protocolo específico para la recolección de datos de plantas invasoras. Posteriormente recolectaron datos y se reunieron para analizarlos y discutir sobre comportamiento ambiental responsable en relación con plantas invasoras. Probamos si los participantes sin experiencia en la identificación de plantas y con poco conocimiento de plantas invasoras incrementaron su conocimiento de ecología de especies invasoras, si la participación incrementó su conocimiento de métodos científicos y si la participación afectó su comportamiento. El conocimiento de plantas invasoras incrementó 24% en promedio, pero la participación no fue suficiente para incrementar el entendimiento de cómo se lleva a cabo la investigación científica. Los participantes reportaron incremento en su habilidad para reconocer plantas invasoras e incremento en la conciencia sobre el efecto de las plantas invasoras sobre el ambiente, pero esto se tradujo en pocos cambios en el comportamiento respecto a las plantas invasoras. Los potenciales conflictos entre las metas científicas, las metas educativas y la motivación de participantes deben ser considerados durante el diseño del programa.