Plant phenology transect at NPP sites

Data Access: 


Dataset status: 

Study number: 


Data set ID: 


Date range: 

1992-07-15 to 2010-12-14

Original investigator: 

Laura Huenneke

Data contact: 


The phenological stage of all perennial plant species on the 15 NPP sites is recorded on a monthly basis.

This allows us to track the influence of weather and of site differences on plant reproduction. The boundaries of the (80m x 80m) study plot are walked and each individual plant of any perennial species in a 1-m belt is examined and its phenology noted (non-reproductive, in bud, in flower, in fruit, or dormant).


field data sheets

Each of the 15 NPP plots is to be monitored monthly (done as near to the 15th day of each month as possible) for the phenological condition of perennial grasses and woody plants. This monitoring will result in counts of plants in each of several states, from which percentages can be calculated. Sampling is done along the west and south side of each NPP plot by walking along the outside of the plot with the center of a meter stick held perpendicular to an imaginary line that connects all the buffer zone corner posts. Exceptions: there are no buffers at the three playa sites or at M-NORT, or along the south side of G-SUMM. On these sites the S and W boundaries of the NPP plot itself are walked with the 100cm end of the meter stick touching the outside of the rebar. At P-COLL the E and N boundaries of the NPP plot itself are walked. In January 2001 there was a change in methodology at P-TOBO; the E and S boundaries are walked. All perennial grasses, shrubs and subshrubs species falling within this 1 meter wide belt will be tallied in one of the following categories: dormant, non-reproductive (non-rep), in bud, fully open flowers, mature fruits. The most advanced phenological stage present is the one recorded; a plant is considered to be in flower (for example), if there is at least one open flower present (even if the majority of flowers are in the bud stage). Tallies are to be done in the dot-box method, where each individual is tallied as either a dot or line; 4 dots from corners of a box, and additional counts are represented as lines joining the corners and forming 2 diagonals (completed box with diagonals = count of 10). Each species in a site will have its own line on the data sheet. The following grass species are considered "path-forming" species: BOER, MUPO, and PLMU. For these species, the entire patch is considered a single tally. A patch is defined as a contiguous area of overlapping vegetation with no easily discernable distinctions between basal units when viewed from above. Certain species of grasses are present in large numbers at some sites. These grasses are measured along a line intercept, as opposed to a belt transect, running between the S and W buffer zone rebars. Each patch or individual of these species that contacts the line is tallied. This method applies to the following grasses at the following sites: BOER - all sites DAPU - M-RABB, C-CALI, and C-SAND MUAR - T-TAYL PLMU - P-TOBO SCBR - G-BASN, T-EAST, T-TAYL, T-WEST SPAI - P-TOBO At two playa sites where PAOB is found in dense stands, each square meter (using the meter stick) along the line was checked for reproductive state rather than the entire line being counted as one. This resulted in high counts of 170 at P-COLL and 140 at P-SMAL. As counts are essential for data analysis, a count is obtained for each plant even when all plants of a species are in a single state rather than just "all" being recorded. In addition to reproductive phenology, information on dates of leaf drop or dormancy in those species which are not green over the winter (or in drought periods) is recorded. Those individuals which have dropped leaves or otherwise appear to be dormant, i.e. grass with no visible green, are tallied in the "dormant" column. If everything is dormant, phenology is not recorded or read to minimize traffic. In certain seasons seedlings are present in large numbers. A separate tally for seedlings should be made and recorded in the comments section on the data sheet. These individuals can be added to the total phenological counts once the plants have reached reproductive size. Certain species require specific instructions regarding method of tallying. At M-NORT and M-RABB, each mesquite dune is considered one PRGL tally. At the three tarbush sites and G-BASN, the dioecious grass SCBR is present; when determining phenology, flowering individuals must be male plants whereas fruiting individuals must be female plants. Note: Individual plant tally numbers will change from month to month as a person cannot walk the exact same transect line each census. Extra effort should be made not to miss individuals of species which are not abundant on a given transect to ensure useable data are collected. Often species abundance changes over time due to recruitment and senescence. If the line-transect method is used for a particular species (such as DAPU) and the number of individuals drops consistently to small numbers, it is appropriate to swith back to the belt transect method with approval from Laura Huenneke. All changes should be noted in the history log. Protocol for Documentation and Data Entry: 1. Enter data into PLPHXXXX.xls immediately following field work (where XXXX represents data set year. Data entry should take less than 15 minutes. Remember to update header 'last updated' information. 2. Save excel file and update NPPPhen.his if necessary. Remember to add update info at the end of the file. Save history file. 3. Send both files to John Anderson for archiving. Any updates to history log or data file added between field days should be sent to John. 4. At the end of the calendar year history log and excel files are sent to John and an ascii version of the data file should be created. a. In excel replace blank cells with periods. Highlight area where blanks should be replaced with zeros. Go to 'Edit' and 'Replace.' Leave the 'Find What' cell blank and add a zero in the 'replace with' cell. Click Replace all. (This may not be available in more recent versions of excel.) b. Left align Column K. Select columns A through K (comment column) and copy. c. In KEDIT open new file. Paste excel columns. Make sure appropriate header and variable information is present. (see other *.dat files if in doubt.) d. Save as PLPHxxxx.dat (where XXXX represents data set year). e. Send ascii version to John. 5. Take raw data sheets and bind them with purple cover sheets. PH_book_cover.doc contains the cover sheet file. 6. Create new excel file for next calendar year (simply open old file, 'Save As' the new file year name, and delete old data points).

Quality assurance: 

Additional information: 

Phenology transects run along the 5 meter buffer on the west and south sides (80m x 80m) of the 15 NPP sites. Transects that begin at the SE (southeast) corner extend to the SW (southwest) corner and then to the NW (northwest) corner. Transects that begin at the NW (northwest) corner extend to the SW (southwest) corner and then to the SE (southeast) corner. The exception is P-COLL site where there is no buffer because of the LTER-I transects on west and east sides. The phenology transect begins at the SE corner (NPP Quad 16) and extends to Quad 1 at the NE corner, then to Quad 37 at the NW corner. 15 NPP Sites: C GRAV Begin SE Corner C SAND Begin NW Corner C CALI Begin NW Corner G SUMM Begin SE Corner G BASN Begin NW Corner T EAST Begin NW Corner P TOBO Begin NW Corner M NORT Begin SE Corner M RABB Begin SE Corner M WELL Begin either end G IBPE Begin SE Corner P COLL Begin SE do E then N T TAYL Begin NW Corner T WEST Begin SE Corner P SMAL Begin SE Corner



Long-term dataset: 

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LTER VI Proposal Category: