Plant phenology or life-history pattern changes seasonally as plants grow, mature, flower, and produce fruit and seeds. Plant phenology follows seasonal patterns, yet annual variation may occur due to annual differences in the timing of rainfall and ambient temperature shifts. Foliage growth and fruit and seed production are important aspects of plant population dynamics and food resource availability for animals. The purpose of this study is to assess plant phenology patterns across a series of biotic communities that represent an environmental moisture gradient. These communites include: Chihuhuan Desert creosotebush shrubland, Chihuahuan Desert black grama grassland, and blue grama grassland. Plant phenology is recorded for all plant species across 4 replicate 200 m transects at each of the 3 habitat sites. Plant phenology measurements are taken once every month from February through October. The first ten individuals of each plant species encountered along each transect are assessed for life-history status. Data recorded include the status of leaves, flowers and fruit. Leaves are recorded as new, old, brown or absent. Reproductive status is recorded as absent, buds, flowers, fruits or both fruits and flowers. Data from the site P and J were only collected in 2000 and 2001 and are included in this data set.
The purpose of this study is to assess plant phenology patterns across a series of biotic communities that represent an environmental moisture gradient.
Locating the Transects:
Phenological conditions are recorded along four permanently marked 200 m x 2 m wide transects at each of the core study sites. The transects are located within four of the five rodent trapping webs. All five transects were originally measured, but in 2003 the least diverse transect at each site was dropped. Each web consists of twelve 100 m transects radiating as spokes from a central rebar stake marked #145. As measured from the center stake, the first four stakes within a ray are positioned at 5 m intervals and the remaining eight at 10 m intervals along a given transect. Plant phenology is recorded along two of these 100 m transects, the transect that extends due north from the central stake and the transect that extends due south from the central stake. The stakes that extend due north are marked 1-12 where stake #1 is closest to the center stake. The stakes that extend due south are marked 73-84 where stake #73 is closest to center.
Collecting the Data:
Each transect is sampled by one technician. Measurements are started from the northern (stake #12) end of each transect. The technician walks in a straight line from one stake to the next surveying a 1 m wide area on each side of the line until the opposite end of the transect is reached. As a transect is walked, phenological conditions are recorded for each species that occurs along the transect. The phenological condition of the first 10 individuals of each species is recorded. After the conditions of ten individuals have been recorded no more observations are made for that particular species even though more may be encountered. Conversely, for rare species only a few individuals may be encountered so there will be less than 10 observations.
Because measurements are taken on separate individuals, it is important to note that many plants have clonal growth forms. This can be seen in some grasses that occur as a clump of overlapping vegetation. In this case each clump is treated as a single individual. This is also true for some cactus and yucca species that appear as a cluster of many individual heads.
Determining Phenological Conditions:
1. New green foliage (N)
This category refers to a plant that is producing new vegetative tissue. The production of new vegetative tissue can be characterized in several ways depending on the species. In many herbaceous plants, new vegetative growth will be indicated by the presence of immature leaves or stems. In herbaceous plants this growth generally appears near the tips of shoots and also at axillary buds.
For species that have a rosette growth form (yucca, some herbaceous plants), the center of the rosette is examined for the presence of immature leaves.
In cacti, the spines are modified leaves and do not readily indicate new vegetative growth so cacti are examined for production of new stems. For example, in Opuntia spp., the presence of a new stem/pad represents new green foliage as each stem-joint represents a season's growth. Cacti that exhibit a cylindrical growth form are more difficult to classify. Cacti with tuberculate stems (Mammilaria spp.) are examined for new tubercules which can often be seen in the center of the head. More problematic are the ribbed cacti where the growth of one season is continuous with that of the preceding season. While these species may be producing new growth it is extremely difficult to identify and thus they are usually categorized as old green foliage.
2. Old green foliage (O)
This category refers to a plant that is not producing new vegetative tissue but exhibits only mature green foliage.
3. Brown leaves (B)
This category refers to a plant that has only brown leaves and is used to indicate a period of senescence or decline.
4. No leaves (Z)
This category is similar to the above category. It is meant to capture a period of senescence or decline and refers to a plant that has subsequently dropped its leaves. It only applies to growth forms that drop their leaves during a period of dormancy or senescence. This category is not used for plants such as Ephedra spp. that normally do not have leaves.
1. New flowers (FL)
This category refers to the presence of flowers at anthesis (open flowers). For many species the petals are large and showy making this condition easy to identify. In species with small or reduced flowers, this condition represents the presence of key reproductive structures such as stamens and/or carpels.
2. New fruit (FR)
This category refers to the presence of a ripened ovary that contains seed. Open fruits that do not contain seed are not categorized as fruiting. Open fruits that do contain seed belong in this category.
3. Fruits and Flowers (FF)
This category indicates that both fruit and flowers are present.
4. No Fruits or Flowers (Z)
This category indicates that neither fruits or flowers are present.
5. Flower buds (B)
This category indicates that only closed flower buds are present.
Each month, the data is QAQCd for typos and incorrect plant codes. To do this in Excel, place the cursor in the first cell of the actual data, not the headings. Go to Data/Filter and select auto filter. Each list formed should fit the parameters listed above. The plant list and the unknown plant list should be updated regularly. Check all errors against the paper data. Be sure that the numbers at the end of the kartez codes are correct. In most cases, all errors can be fixed at this time.
At the end of every year, compile all the data into one file for the year. Check to make sure no data is missing or duplicated. Also, each year, all the previous years data should be updated using the unknown plant list to replace former unknowns with their proper kartez code. At this point all compiled, yearly data sets should be re-archived, replacing the old data sets. Meta data should be maintained with every data set.
Recording the Data:
For each transect, the following is recorded:
1. Recorder- Recorder's initials and also the initials of anyone helping take measurements on that particular transect.
2. The date (month, day, year)
3. The site (B, G, C, J, P)
B = Blue grama grassland
G = Five-Points grassland
C = Five-Points creosote
J = Juniper Savanna
P = Pinon-Juniper woodland
4. The web (1,2,3,4,5)
5. The page number (1/3, 2/3, 3/3)
The species code for all the species occurring along the transect is recorded. Then the phenological conditions of the individual plants in the area are recorded in the Fol and Flw columns of the data sheet. The Fol column is for status codes reflecting the condition of a plant's foliage and the Flw column is for codes reflecting the reproductive status of the plant. The status codes are as follows:
N = new green foliage
O = old green foliage only
B = brown leaves only
Z = no leaves
FL = new flower
FR = new fruits
FF = new fruits and flowers
Z = no fruits or flowers
B = Only buds present
BFL = Buds and flowers
BFR = Buds and fruits
The phenology data is taken with paper and pencil.
For both 2007 and 2008, individual monthly files were checked for errors and compiled in pc_field/phenology. These were uploaded into navicat. Then all the data was exported and put on line with this updated meta data and EML.
Phenology data from 2001-2006 was taken out of flat files and imported into MySQL. Once in the database, I checked for duplicates. These most often happened when a recorder had already taken data for a particular species and accidentally started a new row for data for that species. In these instances, no data was deleted, but the observation numbers were made consecutive. Therefore, they end up with more than 10 observations per web. In no case was this more than 20. The other reason I found duplicates was in years where certain recorders collected separate data for seedlings and adults. In these cases, no data was thrown away and againg the observation number was made consecutive and there also can be up to 20 observations per web for these species. Always in this case the comment "SEEDLING" was added to the relevant observations. I also checked every plant code against the USDA Plants database online at http://plants.usda.gov/ All plant codes that have had nomenclature changes were updated. All previously unknown plants that have since been identified were also updated. All unknown plants that will never be identified were dropped from the database. All typos were corrected. The original code was stored in the database under the collumn title OLD_SPECIES, but is not available online.
Each month, the data should be QAQCd for typos and incorrect plant codes. To do this in Excel, place the cursor in the first cell of the actual data, not the headings. Go to Data/Filter and select auto filter. Each list formed should fit the parameters listed above. The plant list and the unknown plant list should be updated regularly. Check all errors against the paper data. Be sure that the numbers at the end of the kartez codes are correct. In most cases, all errors can be fixed at this time.At the end of every year, compile all the data into one file for the year. Check to make sure no data is missing or duplicated. Also, each year, all the previous years data should be updated using the unknown plant list to replace former unknowns with their proper kartez code. At this point all compiled, yearly data sets should be re-archived, replacing the old data sets. Meta data should be maintained with every data set.
Additional Information on the personnel associated with the Data Collection / Data Processing
Sevilleta Field Crew Employee History
Chandra Tucker (CAT; 04/2014-present), Megan McClung (MAM; 04/2013-present), Stephanie Baker (SRB; 10/2010-present), John Mulhouse (JMM; 08/2009-06/2013), Amaris Swann (ALS; 08/2008-01/2013), Maya Kapoor, August 9, 2003-January 21, 2005 and April 2010-March 2011, Terri Koontz, February 2000-August 2003 and August 2006-August 2010, Yang Xia, January 31, 2005-April 2009, Karen Wetherill, February 7, 2000-August 2009, Michell Thomey, September 3, 2005-August 2008, Jay McLeod, January 2006-August 2006, Charity Hall, January 31, 2005-January 3, 2006, Tessa Edelen, August 15, 2004-August 15, 2005, Seth Munson, September 9, 2002-June 2004, Caleb Hickman, September 9, 2002-November 15, 2004, Heather Simpson, August 2000-August 2002, Chris Roberts, September 2001-August 2002, Mike Friggens, 1999-September 2001, Shana Penington, February 2000-August 2000.
Dates of collection for each field site:
Site B: April 2001 - present
Site C: April 2000 - present
Site G: April 2000 - present
Site J: April 2000 - November 2001
Site P: April 2000 - November 2001