Individual study: The effect of gap creation on the flowering of peony Paeonia mascula in Mount Meiron Nature Reserve, Israel
Ne’eman G. (2003) To be or not to be – the effect of nature conservation management on flowering of Paeonia mascula (L.) Miller in Israel. Biological Conservation, 109, 103-109
Mount Meiron Nature Reserve consists mainly of Mediterranean oak-maquis Quercus calliprinos (Kermes oak)- Pistacia palestina (pistachio). Historically the area had been used for wood-cutting and goat grazing, and deforested to make way for traditional agriculture, which created a habitat mosaic of secondary succession. However, after it was declared a reserve in 1965, these activities were halted and the vegetation succeeded to a dense shaded oak-maquis. This reserve is the sole site of the rare peony Paeonia mascula in Israel, and by 1973 it only occured in 3 km², under shaded conditions, with only 5% of plants flowering. In this study, the effect of gap creation by tree cutting on the flowering of peony was investigated.
Study site: The effect of gap creation by removing scrub and trees on flowering of the peony Paeonia mascula was undertaken in the Mount Meiron Nature Reserve from 1997 to 2001.
Treatments: Fifteen permanent plots (5 x 5 m) with peonies were marked: five plots with flowering peonies were in small open gaps, and 10 plots with non-flowering plants were under closed canopy. Of the latter 10 plots, five had all trees cleared in November 1997 and the other five were left as a closed canopy control.
Peony census: From 1998-2001, in each spring at the end of the flowering season, the number of peony plants and flowers was counted and the height measured in each plot.
Relative photosynthetic active radiation (RPAR): RPAR (400-700 nm) was measured in each plot using an AccuPAR. Radiation measurements were taken between 10:00 and 14:00 h. For each plant within a plot, five measurements were taken above the plant. The average radiation of a plot was taken from four measurements made at each of 16 points 1 x 1 m apart (= 64 measurements).
Peony flowering: In 1998, there was no difference between peony flowering between cleared and closed canopy control plots, while peonies in the open gap plots grew significantly more flowers than both. From 1999-2001, however, plants in cleared plots grew a similar amount of flowers to those in the open gap plots, and much higher amounts of flowers than those in the closed canopy control plots (Table 1, estimated from original figure).
Relative photosynthetic active radiation (RPAR): Average (± S.E.) RPAR of the five sites with flowering peonies (47.4 ± 2.6%) was significantly higher than the 10 sites without flowering peonies (27.3 ± 1.3%). After tree cutting, there was a 10-fold increase in RPAR in the cleared compared to the closed canopy control plots.
Peony height: In 1998, peonies in the cleared plots were significantly shorter than in the open gap plots, but not different in height from those in the closed canopy control plots. In the next three years, peonies in the cleared plots were taller, and there was no difference between them and the plants in the open plots (Table 2, estimated from original figure). Finally, the relationship between the average height of peonies and RPAR suggests that 40% RPAR is the optimal light regime for peony growth.
Conclusions: Creation of 5 x 5 m gaps in closed canopy habitat allows increased photosynthetic active radiation, and it increased peony flowering from 5% to 20%. Consequently, to ensure the survival of this species in Mount Meiron Nature Reserve, one recommendation is to create small gaps by cutting and removal of canopy-forming trees and shrubs.
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