Hiking trails shift plant species' realized climatic niches and locally increase species richness

Testing for synergistic effects of natural and anthropogenic disturbance on ecological communities at a landscape scale

Context

Anthropogenic and natural disturbances may interact synergistically, magnifying their individual effects on biodiversity. However, few studies have measured responses of ecological communities to multiple stressors at landscape scales.

Objectives

We use a long-term dataset to test for synergistic effects of anthropogenic and natural disturbance on plant community diversity and composition in a large protected area.

Methods

We quantified changes in plant communities over two decades in 98 plots in Waterton Lakes National Park, Canada. Fifty-three plots burned in a wildfire in the interim. We modeled the effects of wildfire, proximity to trails or roads, and their interaction on changes in species richness, community composition, relative abundance of disturbance-associated species, and colonization by exotic species.

Results

Interactions between wildfire and proximity to roads and trails affected all metrics except species richness. Only one interaction was synergistic: the relative abundance of disturbance-associated species following wildfire was magnified closer to recreational corridors. The other community metrics showed unexpected patterns. For example, plots with no exotic species in the baseline survey that burned in the wildfire were more likely to gain exotic species than unburned plots only when they were distant from recreational corridors.

Conclusions

Our study demonstrates interactive effects of natural and anthropogenic disturbance at landscape scales within a protected area. Plant community response to wildfire was influenced by proximity to recreational corridors, sometimes in surprising ways. As the frequency and severity of anthropogenic and natural disturbances both continue to rise, documenting the prevalence and magnitude of interactions between them is key to predicting long-term effects and designing mitigation strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10980-024-01844-w.

Not all who wander are lost: Trail bias in community science

The exponential growth and interest in community science programs is producing staggering amounts of biodiversity data across broad temporal and spatial scales. Large community science datasets such as iNaturalist and eBird are allowing ecologists and conservation biologists to answer novel questions that were not possible before. However, the opportunistic nature of many of these enormous datasets leads to biases. Spatial bias is a common problem, where observations are biased towards points of access like roads and trails. iNaturalist-a popular biodiversity community science platform-exhibits strong spatial biases, but it is unclear how these biases affect the quality of biodiversity data collected. Thus, we tested whether fine-scale spatial bias due to sampling from trails affects taxonomic richness estimates. We compared timed transects with experienced iNaturalist observers on and off trails in British Columbia, Canada. Using generalized linear mixed models, we found higher overall taxonomic richness on trails than off trails. In addition, we found more exotic as well as native taxa on trails than off trails. There was no difference between on and off trail observations for species that are rarely observed. Thus, fine-scale spatial bias from trails does not reduce the quality of biodiversity measurements, a promising result for those interested in using iNaturalist data for research and conservation management.

Distribución de plantas nativas y exóticas a lo largo de gradientes de elevación en senderos de montaña en los Andes de Mendoza, Argentina

Introducción y objetivos: El cambio climático, el ganado y el creciente uso turístico favorecen la dispersión de plantas exóticas, amenazando la conservación de los ecosistemas altoandinos. Estudiamos los patrones de distribución de plantas nativas y exóticas en senderos recreativos de montaña. M&M: Implementamos el protocolo MIREN en seis senderos (2400-3600 m s.n.m.) en dos áreas protegidas de los Andes centrales de Mendoza en las Cordilleras Frontal y Principal. Resultados: Encontramos 180 especies nativas y 41 exóticas. La riqueza de especies nativas fue máxima a elevaciones intermedias, mientras que la riqueza de exóticas disminuyó con la elevación. La riqueza regional de nativas fue mayor en la Cordillera Frontal que en la Principal (114 versus 71 nativas, respectivamente) mientras que la riqueza regional de exóticas fue menor en la Frontal que en la Principal (20 versus 28 exóticas, respectivamente). La riqueza de exóticas por parcela fue mayor en la Cordillera Frontal que en la Principal. El rango de distribución altitudinal de exóticas fue mayor en la Cordillera Frontal. Dos exóticas abundantes, Taraxacum officinale y Cerastium arvense, estuvieron a lo largo de todo el gradiente en la Cordillera Frontal, alcanzando los 3600 m s.n.m. Encontramos siete exóticas no citadas anteriormente. Conclusiones: Los nuevos registros amplían los rangos de distribución conocidos para algunas especies exóticas. A pesar de que el número de especies exóticas fue similar cerca y lejos de los senderos, cinco especies sólo estuvieron en los bordes de los mismos, lo que sugiere que los senderos favorecen los procesos de invasión.