NJ Natural Heritage Program, NJDEP Division of Parks and Forestry, Office of Natural Lands Management, 22 S. Clinton Ave, Plaza Bldg 4, Fl. 4, PO Box 404 Trenton, NJ, 08625-0404
N. of intersection of Duck Pond Road and Dove Island Road, off of Duck Pond Rd. (now a handicap path for Swartswood SP). Transect located between large Sycamore hollow at base on W shore to double ash on E shore.
GPS readings for other 3 plot corners: 1-NW) 41.06736, -74.81988; 2-SW) 41.06735, -74.81986; 3-SE) 41.06739, -74.81983
Shape
Rectangular
Area
10
m²
Permanence
permanent plot
Layout Narrative
Plot is 2 x 5 m, 48-50 m along the E side of the transect.
Environment Fields:
Elevation
148.7
m
Slope Aspect
(n/a, flat)
º
Slope Gradient
0
º
Landscape Narrative
Soil Texture: Mineral - marl
General Landscape Description: The area is best characterized as a karst terrain with ridges and valleys that are forested and scattered sinkhole depressions amongst the ridges. Some of the sinkholes are large enough to have several topographic levels - terraced, the lowest in the ponds, middle terrrace supporting floodplain forest, and the upper slopes with calcareous forest (mature and successional).
Known Land Use History: farming (stone wall across pond)
Overall Taxon Cover Values are Automatically Calculated?
no
Plot Quality Fields:
Plot Validation Level
(1) occurrence plot: sufficient for determining type occurrence
Overall Plot Vegetation Fields:
Dominant Stratum
Submerged
Growthform1 Type
Aquatic herb
Growthform2 Type
Herbs
Growthform1 Cover
70
%
Growthform2 Cover
2
%
Misc Fields:
Observation Narrative
General Description: This non-vascular aquatic vegetation community is found in the calcareous sinkhole ponds and marl ponds of the Valley and Ridge Physiographic Province of northwestern New Jersey. The dominant species is the green algae Chara (stonewort). The most common associate is Potamogeton gramineus. The invasive nonindigenous species Myriophyllum spicatum may be present in permanently flooded ponds that are degraded by nutrient input. The associated aquatic species are often site specific and locally abundant. Associated herbaceous species are very sparsely distributed in thick mats of dried Chara. Chara is always present and dominant, however the species composition of associated species varies temporally and spatially, linked inextricably to hydrology and proximal seed bank. This calcareous aquatic community is found on the bottom of solution sinkholes on Allentown Dolomite with glacial till/bedrock complex surficial deposits. Soils are silt marl, shell marl, or rarely silty clay. They are permanently or periodically inundated and very poorly drained. The water is often supersaturated with calcium carbonate that precipitates on the oxygen-rich surface of Chara “stem and leaves”, creating a white granular crust on the algae, and forming granular marl on the pond bottom. This community can occur in ponds that have either constant or fluctuating water levels. When calcareous sinkhole ponds are full of water they often contain dense beds of aquatic algae and pondweeds. In sinkhole ponds that are flooded in the winter and spring but drain completely in the summer and fall, the algae and aquatic plants dry out as they are exposed on the marl surface for long periods of time. The decomposed Chara and calcium carbonate precipitate are fundamental components of marl in karst ecosystems, and may be significant components of dolomite and limestone formations. The hydrology in ponds that support this non-vascular vegetation community is classified as semipermanently flooded. However it exists across the hydrologic spectrum and can be seasonally flooded, semipermanently flooded, or permanently flooded. The hydroperiod range of the ponds in this study is 14 to 20 weeks, averaging 16 to 18 weeks. Seasonal water level fluctuations can be dramatic, ranging between 1 and 18 feet. Aspect is generally flat but can be northwest or southeast, due to the linear, southwest-northeast orientation of carbonate bedrock and ponds. Slope is flat but can also be gentle or moderate in basins with steep sides and dramatic water level fluctuations. This community type is most often found in association with the Panicum capillare – Cyperus strigosus seasonally flooded herbaceous vegetation and the Boltonia asteroides – Aster racemosus – Mentha arvensis seasonally flooded herbaceous vegetation sinkhole pondshore communities.
