populations

A population is a group of organisms of the same species. Like canaries in the coalmine, changes in populations of organisms can be important indicators of environmental changes.

Stream Algae Ash-Free Dry Mass

Abstract: 

As part of the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, a systematic sampling program has been undertaken to monitor the abundance and species distribution of algal mats in glacial meltwater streams of the region. This table contains data showing the ash-free dry mass represented by algal type (brown-colored, red-colored, orange-colored, or green-colored algae, filamentous, sand, rock or moss) and incubation type (light, dark, or none) for multiple streams, dates, and replications.

Data set ID: 

14

Core Areas: 

Short name: 

strmafdm.dat

Methods: 

Within each transect, algal mats were visually identified as either orange, red, black, or green. Not all types of algal mats were found within every transect. A maximum of five algal samples of each color were collected from each transect using a #13 cork borer (diameter = 17 mm, area = 227 square mm). Algal samples were preserved in 10% formalin for laboratory identifications. In all, 141 algal samples were collected from 12 streams. maximum of five additional algal samples of each color were collected for ash-free dry mass analyses. Moss samples were also collected using the same method as for algae samples. Samples for ash-free dry mass measurements were filtered through GF/C glass fiber filters and frozen. The samples were dried (100 degrees C) for 24 hours, weighed, ashed (450 degrees C) for 4 hours, rehydrated with water, dried for 24 hours, and reweighed.

Data sources: 

strmafdm

Maintenance: 

Data from this table was initially included in the raw data files specified under the variable for 'file name'. These are Microsoft Excel version 5.0 files and can be found on the McMurdo LTER data manager's personal computer at INSTAAR. Once submitted to INSTAAR, the data manager combined all of the stream biology files that included information for "ash-free dry mass", and removed any variables that had no direct influence on it. The resulting files are represented in the "strmafdm.dat" and "strmafdm.txt" files used on the web page. In July, 2000, dataset code and location code (strmtrnsid) fields were added. This would simplify generating links between different data and metadata fields and assist in making the data more relational / useful in Oracle and ArcInfo.

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