Treesearch

In its invaded range in western North America, Bromus tectorum (cheatgrass) can host more than 100 sequence-based, operational taxonomic units of endophytic fungi, of which an individual plant hosts a subset. Research suggests that the specific subset is determined by plant genotype, environment, dispersal of locally available endophytes, and mycorrhizal associates. But, interactions among members of the endophyte community could also be important. In a sampling of 63 sites throughout the invaded range of B. tectorum, a fungivorous nematode, Paraphelenchus acontioides, and an endophyte,...

Proper management of naturally forested landscapes requires knowledge of key disturbance processes and their effects on species composition and structure. Spatially-intensive fire and forest histories provide valuable information about how fire and vegetation may vary and interact on heterogeneous landscapes. I constructed 800-year fire and tree recruitment chronologies for two eastern Great Basin fire-sheds using fire-scar and tree establishment evidence from 48 gridded plots (500 m spacing) and from fire-scarred trees between plots. Fire-sheds are located in the Snake Range of eastern...

In 2009, we repeated a freshwater turtle survey first conducted in 1976 in the Lower Rio Grande Valley (LRGV) of Texas to determine whether the abundance of freshwater turtles in the LRGV has changed over the past three decades. We captured significantly fewer red-eared sliders (Trachemys scripta elegans) and Texas spiny softshells (Apalone spinifera emoryi) in 2 recently urbanized counties (Cameron and Hidalgo), and more red-eared sliders and Texas spiny softshells in a nonurbanized county (Willacy). Landuse changes, increased urbanization, and commercial turtle harvest are likely...

Mountain pine beetle outbreaks have caused widespread tree mortality in North American forests in recent decades, yet few studies have documented impacts on carbon cycling. In particular, landscape scales intermediate between stands and regions have not been well studied. Remote sensing is an effective tool for quantifying impacts of insect outbreaks on forest ecosystems at landscape scales. In this study, we developed and evaluated methodologies for quantifying aboveground carbon (AGC) stocks affected by mountain pine beetle using field observations, lidar data, and multispectral imagery....

The unique vegetation assemblage of the Black Hills in conjunction with the frequent occurrence of natural and anthropogenic disturbances emphasizes the need to use locally adapted native species in a wide variety of restoration efforts. However, a general lack of information regarding germination and propagation requirements for most native plant species has restricted their usage. A better understanding of dormancy and germination patterns for native species will increase their availability and affordability. We selected two common native species, hairy goldaster (Heterotheca villosa)...

Blackbrush (Coleogyne ramosissima Torr. [Rosaceae]) is a landscape- dominant shrub that occurs in an ecotonal band between warm and cold deserts of the western US. This vegetation type is at considerable risk from stand-replacing wildfires due to the introduction of exotic annual grasses. Because blackbrush does not form a persistent seedbank, restoration following fire requires that seed produced in mast years be collected and stored for future use. This study examined germination of 32 collections of blackbrush seed following 12 to 27 y of storage at room temperature. Germination and...

Although some may doubt its usefulness in a future with rapidly changing climates, exotic introductions, and increased human land use, the historical range of variation (HRV) of ecological landscape characteristics provides a relatively useful reference point for evaluating the impacts of landmanagement activities. Unfortunately, comprehensive spatial and temporal data describing historical landscape conditions are rare for many areas, with most information being limited in geographic scope and relatively recent. The main problem facing many ecologists, scientists, and land managers is how...

Simulation modeling can be a powerful tool for generating information about historical range of variation (HRV) in landscape conditions. In this chapter, I will discuss several aspects of the use of simulation modeling to generate landscape HRV data, including (1) the advantages and disadvantages of using simulation, (2) a brief review of possible landscape models. and (3) the pitfalls and limitations of the simulation approach. This information provides a reference for planning, preparing, implementing, and interpreting HRV simulations and their results.

Seasonal variations in background aerosol optical depth (AOD) and aerosol type are investigated over various ecosystems in China based upon three years' worth of meteorological data and data collected by the Chinese Sun Hazemeter Network. In most parts of China, AODs are at a maximum in spring or summer and at a minimum in autumn or winter. Minimum values (0.10~0.20) of annual mean AOD at 500 nm are found in the Qinghai-Tibetan Plateau, the remote northeast corner of China, the northern forest ecosystems and Hainan Island. Annual mean AOD ranges from 0.25 to 0.30 over desert and oasis...

Geomorphic and ecological effects of instream wood have been documented primarily along rivers in the temperate zones. Instream wood loads in tropical rivers might be expected to differ from those in analogous temperate rivers because of the higher transport capacity and higher rates of wood decay in the tropics. We use data from four field sites in Costa Rica and Panama to demonstrate that wood loads are consistently lower in tropical rivers, despite substantial variations among tropical sites as a result of differences in mechanisms of wood recruitment. We develop a model of wood...