Herb population responses to large-scale disturbance on W5:
        Surveys of the herb population on W5 were conducted periodically after the harvest to monitor changes in the distribution pattern of individual species as a result of the disturbance and subsequent regrowth.

        1. Abstract
        2. Figure 1:  Wood aster and hay-scented fern
        3. Figure 2:  Red and painted trillium
        4. Figure 3:  Canada mayflower, bluebead lily and Indian cucumber root
        5. Figure 4:  Wood sorrel, shining club moss and spinulose wood fern
        6. Figure 5:  Red and painted trillium 1985-1997
        7. Table 1:  Frequency of occurrence for all species

 


1. Abstract

          We monitored changes in the populations of the dominant herbs on W5 using a network of 350 1x1 m permanent, mapped plots.  These plots were surveyed before harvest and in years 1, 2, 5 and 11-14 after harvest.  We hypothesized that the populations of understudy herbs would respond to the disturbance in predictable ways on the basis of their life history characteristics, especially shade tolerance, phenology and mode of reproduction.  The hypothesis generally was supported.  For example, populations of the intermediate shade tolerant herbs, Trillium undulatum and T. erectum, increased dramatically on W5, especially during the later years (see Figure 5);  this result was explained by high survivorship of pre-existing individuals and a marked increase in reproduction resulting from accelerated maturation.

          Herb species were classified into four categories on the basis of life history  features and reproductive modes that were expected to influence responses to large-scale disturbances.  Group 1 species were relatively shade intolerant, long-distance dispersers, like Aster acuminatus and Dennstaedtia punctilobula.  Measurements of abundance and pattern included stem density, frequency of occurrence at a 1 m2 scale, and Greens's index of clumping (GI), a measure of dispersion. High values of GI indicate pronounced clumping.

        Data and tables are from a thesis by Anna Stalter at Cornell University. "Patterns of herbaceous response to a clearcutting disturbance in a hardwood forest".
 
 
 

2. Figure 1


Density, frequency of occurrence, and GI of group I species 
following the whole-tree harvest: 
A) Aster acuminatus (Whorled wood aster) and 
B) Dennstaedtia punctilobula (Hay-scented fern)


 

 
 
 
3. Figure 2

        Density, frequency of occurrence, and GI of group II species 
following the whole-tree harvest: 
A) Trillium erectum (Red trillium) and 
B) Trillium undulatum (Painted trillium)


 

 
 
 
4. Figure 3

Density, frequency of occurrence, and GI of group III species 
following the whole-tree harvest: 
A) Maianthemum canadense (Canada mayflower) 
B) Clintonia borealis (Bluebead lily) and 
C) Medeola virginiana (Indian cucumber root)


 

 
 
 
5. Figure 4

Density, frequency of occurrence, and GI of group IV species 
following the whole-tree harvest: 
A) Oxalis acetosella (Northern wood sorrel) 
B) Lycopodium lucidulum (Shining club moss) and 
C) Dryopteris spinulosa (Spinulose wood fern).


 

 
 
 
6. Figure 5

Density of Trillium erectum and T. undulatum in W5 
Hubbard Brook Experimental Forest, 1985-1997.


 

 
 
 
7. Table 1

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Web page created June 2000
by Thomas Siccama and Ellen Denny