ABSTRACT
Active management practices to reduce or promote particular vegetation, known as vegetation treatments, are a common part of environmental management and they are conducted for a variety of purposes including wildfire risk mitigation, invasive species management, and ecological restoration. Vegetation treatment for wildfire mitigation in particular have increased dramatically in the Western United States in the past several decades. While vegetation treatments are common, data regarding the timing, location, and type of treatments conducted are often only maintained by the organization that conducted the work, hampering the ability of managers and researchers to understand the distribution and timing of vegetation treatments across a landscape. This dataset is a collection of spatially referenced records of vegetation treatments such as mechanical thinning, prescribed burning, and herbicide applications that were conducted in the state of New Mexico, USA and adjacent parts of Colorado, Oklahoma, and Texas. Spatial data were collected through requests to the regional or state offices for the relevant agencies (e.g., The Bureau of Land Management, the U.S. Forest Service, New Mexico State Forestry Division). The accuracy of this data collection approach was assessed by conducting more intensive data collection in five randomly selected focal watersheds across New Mexico. In these watersheds local offices of the larger agencies were contacted, as well as any smaller groups (e.g., soil and water conservation districts, municipalities, and environmental non-profits), and in person visits were made to gather any information on vegetation treatments possible. The overall dataset includes records of treatments spanning a century and includes records of 9.9 million acres of treatments conducted by more than a dozen different organizations. In the five focal watershed that we surveyed the database contained 7.4 % fewer acres of treated land than the more intensive interview approach. This spatially extensive dataset on vegetation treatments will be useful for researchers quantifying or modelling the effect of vegetation management on fire risk and behaviour. Additionally, this data will be useful to ecologists studying the distribution, movement, and habitat associations of a variety of plant an animal species. Finally, this data will be useful for research on landscape conservation and management.
ABSTRACT
Invasive grasses are a threat to some tropical savannas, but despite being fire-prone ecosystems, little is known about the relationships between fire season, climatic conditions and invasive species on these systems. We evaluated the response of the perennial invasive grasses Melinis minutiflora and Urochloa brizantha to three fire seasons in an open tropical savanna in South America: Early-Dry (May), Mid-Dry (July) and Late-Dry (October) in relation to unburned Controls. Moreover, we investigated how these responses were influenced by precipitation and extreme air temperatures. We hypothesized that biomass of both species would be reduced by fires during their reproductive period and that climatic conditions would affect them equally. We conducted prescribed burns on 15 × 15 m plots (4 plots x 4 treatment x 2 invasive species = 32 plots) in 2014. We sampled the biomass before the burn experiments and for the next two years (five 0.25 m2 samples/plot). Our experiments revealed that the fire season did not influence the abundance of either species. However, the two species responded differently to fire occurrence: M. minutiflora decreased whereas U. brizantha was not affected by fires. Early-Dry and Late-Dry fire treatments enhanced the replacement of M. minutiflora by U. brizantha. We found that the influence of precipitation depended on the species: it reduced M. minutiflora but increased U. brizantha abundance. Lower monthly minimum temperatures decreased the abundance of both species. It directly reduced live M. minutiflora and increased dead U. brizantha biomass. Monthly maximum temperatures affected the invasive grasses by reducing live M. minutiflora. Since tropical savannas are predicted to face climatic instability and that climate influences the differential response of invasive species, the management of invaders should consider both the identity of the target species and the possible interactions with other invasive species. Moreover, it is essential to keep an adaptive management approach to face the uncertainties that climate change may pose to biodiversity conservation.