Fern leaf traits observation at the Luquillo Experimental Forest (LEF)



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Ferns are a common element of the understory of forests, yet little is known about the dynamics of leaf production. The long-term role of an individual fern in the ecosystem understory is a function of the number and size of leaves produced over time and the quality of those leaves. Selected functional plant traits (see also LUQ187 -Fern nutrients) were measured in order to supplement non-destructive measurements and detect patterns of primary productivity of ferns in the long-term studies at the Luquillo forest where ferns have been included (eg. Fern growth and demography (LUQ75), Canopy Trimming Experiment (LUQ143 and LUQ146) and the Luquillo Forest Dynamics Plot). Among the important characteristics of fern leaves in the forest understory are the area and biomass of leaves needed to calculate specific leaf area (SLA), leaf dry-matter content (LDMC) and leaf shrinkage. Therefore a large sample of whole leaves and leaf material from several species in the Luquillo Experimental Forest understory was collected, weighed and leaf area measured. The means and regression relationships among these functional traits for species, leaf type and leaf size can then be used to estimate leaf production and turnover rates in temporal studies of fern growth.

Date Range: 
1996-05-21 00:00:00 to 2014-06-09 00:00:00

Publication Date: 

2015-03-02 00:00:00





Leaves of 17 understory fern species were collected. Leaves that were selected were mature, mostly free of damage and young enough to be free of any signs of epiphyll growth. Early collections were taken when time permitted during monitoring visits throughout the duration of the longterm growth and demography study (LUQ75, 1991-2010) from leaves of experimentally defoliated plants and from untagged plants in the study areas. These collections were dried in a plant press until dry weight remained unchanged and weighed with a Metler balance. They were then taken from Luquillo and stored in plastic bags in a dry room. Additional leaves and leaf material were collected in June 2014. These freshly cut leaves were weighed and leaf area and thickness measured the same day as collected. They were then flattened and dried in the drying oven at the El Verde Field Station to 70 degrees C to obtain dry weights. Leaf areas were determined by scanning the leaves (Epson V550) and using ImageJ to measure lengths, widths and areas of leaf petioles, lamina and for some compound leaves, rachis and leaflets. Fresh and dry leaf lengths and leaf areas from the leaves collected in 2014 can then be used to calculate shrinkage rates, SLA and LDMC of leaves and leaf parts of the other dry leaves in the sample, and for living leaves included in long-term studies at the Luquillo LTER site.



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