USGS Science⌕ Search

SEARCH · USGS Science

Results for “Growth”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
USGS2017

The growth of sport shooting participation: What does this trend mean for conservation revenue?

Enacted in 1937, the Federal Aid in Wildlife Restoration Act – more commonly known as the Pittman-Robertson Act – is one of the oldest and most reliable sources of funding for wildlife conservation in the United States. The result of organized support form sportsmen, fish and wildlife agencies, firearms manufacturers, conservation organizations, and even garden clubs, the PR Act created an excise tax on so-called “long guns” and ammunition used by hunters, thereby establishing the first sustainable source of revenue dedicated to conservation and land management efforts throughout the country. Later, legislators amended the PR Act to include an excise tax on pistols, revolvers, bows, arrows, and other archery equipment.

The Wildlife Professional↗
USGS1998

Characterization of an old-growth bottomland hardwood wetland forest in Northeast Texas: Harrison Bayou

Most wetland losses in the southern region over the past 200 years have occurred in bottomland hardwood forests. By 1980 the original extent of palustrine bottomland in Texas had been reduced by 63%, from roughly 16 to 6 million acres. Additional losses have occurred during more recent years as a result of conversion to agriculture and timber harvests; these factors and the need to supply new hardwood chip mills in the region pose a potential threat to the remaining hardwood resource. The Harrison Bayou watershed in northeast Texas contains one of the few relatively undisturbed bottomland hardwood wetland forests in the State. Harrison Bayou is part of the Caddo Lake wetlands complex, most of which was designated a Wetland of International Importance under the Ramsar Treaty in October of 1993. Caddo Lake State Park is one of fifteen "Ramsar" wetlands in the United States; it is the only wetland with this designation in the State of Texas. Harrison Bayou is an important component of the Caddo Lake watershed; it represents a model bottomland hardwood wetland in both structure and ecological function. Three major forest cover types illustrate the diversity of the 600-hectare bottomland hardwood/baldcypress forest at Harrison Bayou. Comparison of wetland forest extent and species composition in 1977 with 1993 revealed very little change in wetland forest community structure.

Texas↗
USGS1993

Thermal stratification of dilute lakes - evaluation of regulatory processes and biological effects before and after base addition: effects on brook trout habitat and growth

Addresses the significance of changes in summer thermal stratification patterns of Adirondack lakes affected by acidification to cold-water fish populations inhabiting these sensitive lakes . Brook trout Salvelinus fontinalis is the primary cold-water fish species indigenous to acid-sensitive lakes in the Adirondack region of N New York State; the ability of these lakes to sustain this important sport species is highly dependent on the availability of adequate summer habitat, consisting of cool, well-oxygenated water. Brook trout populations presently most susceptible to negative effects from acidification-induced increases in transparency and consequent reductions in preferred thermal habitat occur primarily in shallow, low-color lakes that are marginally acidified and either weakly stratified or strongly stratified with anoxic hypolimnia. Significant improvements in brook trout thermal habitat could be achieved in these lakes by reducing acidity levels, eg by liming.

New York↗
USGS2020

Nexus between wildfire, climate change and population growth in California

Since the year 2000 California has experienced a remarkable upsurge in wildfires. Over five million hectares have burned in the last 20 years, which is double the area burned in the previous two decades. Much of this increase has been driven by large fires of more than 50,000 hectares that cause catastrophic losses of lives and property (Keeley and Syphard 2019). This increased fire activity has been correlated with an increase in average temperature over this same period, leading many observers to assert that global climate change must be playing a major role. Climate models forecast continued warming and thus some have suggested these catastrophic fires are the “new normal” or the “new abnormal” (Birnbaum 2018). In contrast, others have declared that these fires are the result of ‘forest mismanagement’ (Cranley 2018) and this has stimulated renewed interest in fuel reduction (Office of Governor 2019). It’s almost as though these opinions aren’t even in reference to the same fires, and as described below, there is some validity to this assertion.

California↗
USGS1974

Geometry and growth of the White Sands dune field, New Mexico

Recent studies of the cores from four drill holes at the White Sands dune field in New Mexico demonstrated that the eolian sand body below the present active dunes ranges in thickness from 23 to 34 ft in the area tested. It consists of one to two older generations of dune and associated interdune deposits, which rest on playa and fluvial deposits. Relatively thick sheets of clean, well-sorted dune sand are separated from one another by thin zones of darker colored interdune deposits. In vertical sections of test trenches and in cores, these interdune deposits appear as thin zones of tan or buff, poorly sorted, subparallel strata between relatively thick units of white cross-stratified sand. The interdune deposits are buried by the advancing foresets of the encroaching dunes and their thickness is limited by the time of exposure. The subsurface dune deposits are relatively thin as compared to the active surface dunes. This difference in thickness apparently results from the beveling or truncation of dunes by the migration of interdune areas.

New Mexico↗