Chapter 8. Dalea Carthagenensis (Jacq.)J.F.Macbr

Chapter 8. Dalea carthagenensis (Jacq.)J.F.Macbr. var. floridana (Rydb.) Barneby

Jennifer Possley and Stephen R. Hodges

Introduction

The sub-shrub Dalea carthagenensis var. floridana (Florida prairie clover) is a Florida endangered species and a candidate for the USFWS endangered species list (USFWS 2010). It is endemic to South Florida, and is found only in Miami-Dade and Monroe Counties. The taxon (hereafter “Dalea”) can be found only in four protected areas: Big Cypress National Preserve and three small Miami-Dade County preserves: CDE, RHMP and CR. It is also known to be present in three unprotected private properties in the Cutler Bay area of Miami-Dade County. This taxon is found in the ecotone between hammock and pineland as well as in the coastal strand plant community at CR.

Updates on Monitoring Wild Populations of D. carthagenensis var. floridana

Over the prior year we have monitored all known sites that we could access. We specifically targeted locations where Dalea was known to occur in the past but which have not been surveyed in several years. Additional survey work was conducted in the Goulds area where Dalea occurs on 3 private unprotected parcels. Unfortunately our search did not locate any additional populations. There was a 1930 collection of Dalea by Harold N. Moldenke from the edge of Cox Hammock (646, NY) (Gann 2002). On March 25 of 2014 Jennifer Possley and Stephen Hodges visited the Monkey Jungle, former site of Cox’s Hammock. We surveyed there but did not locate Dalea.

Big Cypress Preserve

On January 15, 2013 Fairchild staff members Stephen Hodges and Joyce Maschinski were joined by Big Cypress National Preserve botanist Jim Burch and Everglades National Park botanist Jimi Sadle to survey the four known populations of Dalea. We were able to relocate plants in two of them. At location A, north of Oasis visitor center, we counted 65 adults, 42 juvenile plants and 129 seedlings. All plants are immediately adjacent to a dirt road in a pineland hammock ecotonal community. Potential threats to the plants include possible road work. This population represents the vast majority plants remaining in the Big Cypress.

Site B is along 11 mile road in mesic pineland with nearby hammock areas. Despite our surveys we were unable to relocate this population. The area where they were thought to have been present is now heavily overgrown with hardwoods and so we suggest that surveys be conducted again if that area ever burns.

Site C and D are both located along Loop Rd. We were unable to locate plants at site C, but did find plants at site D. The area is immediately adjacent to the road, there has been some dumping at the location and exotics have encroached. The plants appeared unhealthy. We counted 9 adults, 7 juveniles and 1 seedling at the site. We recommend germplasm collection both for long term seed storage, but also to make sure that plants can be reintroduced in a more appropriate location in the immediate vicinity.

Unprotected Private Locations

There are three known sites where Dalea populations exist on unprotected land. We have been able to visit two of these locations, sites STF and HRS. The third location is a parcel of land owned by FPL. All three locations are highly disturbed and plants are growing in precarious scenarios. These locations are presumably along the historic black creek and are all within reasonable proximity to the current C1 canal.

Other potential locations for Dalea exist in this area, the best of which would probably be Black Creek Forest, owned by Miami-Dade County. That site has been surveyed many times but there have been no reports of Dalea being present at the site. Other undeveloped locations exist along the C1, many of which are disturbed and overrun with exotics. All of the sites we have been able to locate where Dalea might be present are privately owned and some pose somewhat of a security risk to survey. We surveyed locations from the vehicle or roadside in several cases, but have located no other populations. 31 Because a bike trail travels along much of the C1 canal, it would be possible to survey the canal banks and trail sides for possible presence of Dalea, but this has not been done yet.

We visited site STF on March 11th, 2014. This site is owned by a neighborhood association and is a highly degraded hammock with active dumping and a large invasive exotic plant presence. Plants exist on the edge in an area that is probably mowed occasionally. We located 2 adult plants and 15 juveniles. In March of 2011 Keith Bradley sent Institute for Regional Conservation data indicating population estimates for all known Dalea locations. He visited site STF with Sam Wright of Fairchild in 2010 and they estimated a total of 40 plants at the site.

We also visited site HRS on March 11th, 2014. This location is owned by Miami-Dade county public health trust and sits adjacent to a community health clinic. The site is ostensibly a natural area that had been overrun by invasive exotic plants (Figure 8-1). Apparently, there has been a major effort to remove some of these and much of the area has now been cleared, but the site is highly degraded. We located 3 adults and 18 juveniles. The plants are surrounded by disturbed species, both native and exotic, and there is the potential for the plants to be unintentionally harmed by crews clearing exotic vegetation.

On the same day we surveyed the FPL site from outside the property line. This property is highly impacted by invasive exotics, dumping and homeless activity. There are potential security concerns involved in surveying the property and if plants do remain there, every opportunity should be made to collect germplasm and possibly transplant individuals as soon as possible. Fairchild staff will continue to make efforts to gain access to the site.

Figure 8-1. Dalea habitat at site HRS. The vegetation primarily consists of disturbed area species, invasives exotics and other weedy species.

32 CDE

From 2003 to 2007, the number of woody Dalea in CDE’s north pineland was between 50 and 80 individuals, with the number of seedlings ranging from 3 to 54. In the past 5 years, we have documented pulses of seedling establishment (Figure 8-2). We conducted annual monitoring at CDE in January 2014, finding that the total population size in the north pineland (seedlings + woody plants) was 347 individuals, a very slight decline from the previous year’s survey.

Figure 8-2. Census data for Dalea in CDE’s north pineland (2003-2014).

33 RHMP

From 2004-2008, the Dalea population at RHMP diminished from 31 woody individuals to just one woody plant and three seedlings (Figure 8-3). In summer 2009, the wild population surged to 330 seedlings. We conducted annual monitoring at RHMP in January 2014, finding 98 individuals, a slight decline from the previous years’ survey. This does not include Dalea that resulted from our 2009 seed augmentation at RHMP (see below).

Figure 8-3. Census data for Dalea at RHMP (2003-2014)

Update on experimental seed augmentation

Jennifer Possley and Joyce Maschinski

By 2008, the Dalea population at RHMP appeared to near extirpation, with only four plants present. To bolster the declining wild population, we conducted an experimental seed augmentation. As reported previously, we initiated an experimental reintroduction of 6000 Dalea seed at RHMP in summer 2009. In brief, we introduced seeds that had been either frozen or not into intact pineland (with leaf litter raked away) or to a restored area (see Possley et al. (2010) for complete details). In 2010, we noted 152 Dalea had established in our experimental plots. During annual monitoring in January 2014, we documented 88 established plants. Of these, 36 were new (non-woody) seedlings. We returned to the augmentation plots again in late February 2014 and it was apparent that many more seedlings had germinated in the last two months. We re-conducted our census and counted 208 non-woody seedlings and 52 woody plants. We did not notice a similar germination pulse in the wild population, indicating that our augmentation may prove to be very important for the preservation of Dalea at RHMP.

We submitted a detailed manuscript on this seed augmentation to American Journal of Botany in April 2014. In addition to describing the field augmentation, we incorporated information on seed biology obtained through cooperative research with the USDA National Center for Genetic Resources Preservation (Maschinski et al. In review).

Next Steps

We will continue annual monitoring of Dalea populations in Miami-Dade County preserves, including wild and reintroduced populations.

References

Maschinski, J., J. Possley, C. Walters, L. Hill, D. Walters, L. Krueger, and D. Hazelton. In review. How seed biology influences Dalea carthagenensis (Fabaceae) episodic recruitment, demography, restoration, and population persistence in pine rockland habitat. Manuscript submitted to Am. J. Bot., April 2014.

Possley, J., J. Maschinski, and L. Krueger. 2010. Year 7 report: Biological monitoring for plant conservation in Miami-Dade County natural areas. Miami-Dade County Resolution #R-808-07.

35 Population Trends at CR and Factors influencing Pulses of Dalea Seed Germination

Joyce Maschinski

Dalea carthagenensis var. floridana is under severe threat from fire suppression, invasive exotic species, and human activities that have contributed to an alteration or reduction of its habitat. We examined population growth patterns of the federal candidate species growing in coastal strand habitat from 2007- 2014.

Methods

Demography Study

At Site CR in February 2007 we initiated demographic studies of D. carthagenensis var. floridana growing in coastal strand. The demographic plot measuring 3m X 10m, stretched randomly through the total population area of 145m2 and sampled approximately 70% of the population. In 2007 we estimated population size as 1000 plants. In 2012 we expanded the demographic monitoring plot to encompass an additional 3 m X 10m area because a portion of the 2007 plot has not supported many plants for several years. In 2014, we estimated the total plants at CR to be 500 plants.

Each year we tagged new individuals, recorded location along the x and y axes of the plot and measured height, perpendicular widths 1 & 2, and counted the number of inflorescences. We categorized plants into one of four growth stages: 1) seeds in the seed bank; 2) seedlings were not woody and had 10 or fewer leaves. Some had cotyledons present. 3) Juveniles were woody plants lacking inflorescences, with > 10 leaves and generally > 15 cm tall. 4) Reproductive adults had inflorescences present.

We generated population viability models under scenarios of germination from the seed bank where seeds received germination cues (with) and when seeds did not receive germination cues (without cues). We used CR demographic data for eight transition periods between 2007-2014. This timespan included 2009-2010, when high seedling recruitment occurred and six transition years when low seedling recruitment occurred. For each transition year, we created matrices for two scenarios simulating years with environmental germination cues (WITH CUE) and without environmental germination cues (NO CUE). Vital rates for percent survival and transitions to larger stages for plants in three stages (seedlings, juveniles, and reproductive adults) were fixed for each transition year based upon observations of survival and mortality of plants in the stages. We varied seed bank stasis, seedling emergence from seed bank, and reproductive value to simulate years with and without environmental germination cues. We used field control and freezing pretreatment germination rates as the vital rates for seedling emergence from the soil seed bank (Field Control (no cue) = 4%; Frozen (with cue) = 9%). To estimate the seed bank size we determined the number of viable seed present within 15 inflorescences by visually assessing the proportion of good seeds and testing their germination and viability in the laboratory. We determined that the average proportion of good seeds within an inflorescence was 0.54. We derived reproductive values for models with and without germination cues from the formula: (inflorescence/adult) * 0.54 (mean proportion good seeds/inflorescence) * average germination (with germination cue 0.96 and without germination cue 0.205) * 0.33 (the average proportion of adults to contribute more than 20 seeds in a year). Because we had no measure of seed mortality in the seed bank from herbivory or other causes, we assumed 26% mortality for seeds in the seed bank based upon Chambers (2001). In addition we modeled a range of seed bank mortality from 1%-100% for 2010-2011 to assess how this assumption affected elasticity values and lambda. Using the stochastic simulation program RAMAS GIS (Akcakaya, 2005), we generated models with 1000 simulations over 50 years, and calculated population growth rate, extinction risk, and elasticities for each transition year and scenario.

Seed Research

To understand what environmental factors may trigger germination or conversely seed storage in the soil seed bank, with NCGRP colleagues we conducted seed germination research. We compared speed of germination and total percent germination of fresh D. carthagenensis var. floridana seeds exposed to several treatments. We collected seeds for experimental use in Feb 2007 from plants of CR provenance growing in the Fairchild greenhouse and in March 2011 from wild CR plants. We dried seeds at 25% RH and stored at 5oC for 1 month until used. We conducted germination trials at Fairchild Tropical Botanic 36 Garden with the 2007 collection and at the National Center for Genetic Resources Preservation with the 2011 collection. To simulate conditions seeds might experience in the wild, we applied treatments to seeds after exposure to water on blotter paper (hereafter called “sown”). We imposed freezing or clipping treatments to sown seeds that had not germinated within at least 17 days. Treatments were: 1) Clipped where we clipped seeds using a razor blade, making a shallow slice through the seed coat at the end distal to the embryonic axis after 123, 274 and 600 days; or 2) Frozen, where we placed petri dishes with seeds sown on damp blotter paper for 17, 86 and 138 days into a standard freezer (-20oC) for 3 days, then returned each to the 25oC growth chamber. The 17 and 138 day treatments used 2011 cohort seeds, while the 86 day treatment used 2007 cohort seeds. Conducting trials of sown seeds for up to 600 days allowed us to assess how long seeds remained viable.

In a second set of trials, we exposed 2011 cohort unsown seeds (i.e., seeds at ambient temperature and humidity that had not been exposed to water on blotter paper) to clipping, scarification with sandpaper, and freezing pretreatments to quantify permeability of the seed coat (Table 2). The specific treatments were: 1) Clipped, which involved clipping seeds using a razor blade, making a shallow slice through the seed coat at the end distal to the embryonic axis; 2) Dry scarification, where we dried 30 to 50 seeds to 14% RH (placed over a saturated LiCl solution) for at least 5 days and scarified them using a modified stone polishing device fitted with 220 grit paper and held the pressure at 5 psi for 0.5, 1, 2 and 4 minutes; 3) Moist scarification, in which we placed 30 to 50 seeds moistened over wet paper towels (~100% RH) for 5 days and scarified with 220 grit sand paper for 0.5, 1 and 2 minutes; 4) Freeze-thaw, in which we froze 99 seeds at -20oC for 2 days and returned them to the 25oC incubator; and 5) Control, where seeds received no pre-treatment.

For all trials we placed seeds on damp blotter paper in Petri plates sealed with parafilm and held them under a 12hr light cycle at 25oC. We recorded radicle emergence daily for the first 7 days after sowing, then twice a week for the first month and monthly thereafter. In addition, we compared the fresh mass of dry seeds with those that had not germinated after 600 days under germination conditions.

Using a generalized linear model with a binomial error distribution, we examined the significance of clipping, scarification and freeze treatments on germination relative to untreated controls (Crawley, 2012). We treated germination as proportional data and seed abrasion treatments and time after sowing (if relevant) as categorical variables (Crawley, 2012). For each treatment group, we calculated germination speed as (G1-Gf) : (T1-Tf), where G is the germination proportion and T is time after sowing and subscripts 1 and f are time for first and final germination event.

Results

Population Growth

The population at CR declined by 33% from 2007 to 2009, but high seedling recruitment increased numbers by 2010 and numbers stabilized until 2014 when a second pulse of high recruitment occurred (Figure 8-4). Most seedlings recruited in partial shade beneath adult plants. In most years we observed low levels of recruitment, however high seedling recruitment occurred in 2010 and 2014.

During our demographic study 3 transition years had declining growth and 4 transition years had stable or increasing growth. This cyclic pattern is characteristic of short-lived species. Whether there is a cyclic pattern to high germination pulses is yet to be determined. As we study these plants for more years we will be able to gather more information to substantiate this idea.

The 2010 recruitment coincidentally occurred during a cold wet winter of 2009-2010, while the 2014 recruitment occurred during a cold dry winter (Figure 8-5). Unfortunately high seedling mortality followed the high 2010 recruitment event. Time will tell whether the 2014 seedlings will have good survival. When we examined winter weather patterns for the past 86 years from online sources, we discovered that all of the years in which we’ve observed high recruitment at CR, RHMP, and DER have been comparatively cool winters, while precipitation has not shown a pattern.

Figure 8-4. Numbers of Dalea carthagenensis var floridana seedlings, juveniles, and adults alive in demographic plot at CR in 2007- 2014.

Figure 8-5. Minimum winter temperature versus total winter precipitation climate patterns from 1927-2013 in South Florida. High recruitment years are indicated with large black squares. Demographic monitoring years with low recruitment are indicated with large circles. All other years are diamonds. The dotted lines indicate boundaries of + 1 SD of mean values, while the central solid line divides the average quadrat. Note that years of high recruitment at CR, RHMP and DER are all on the left side of average minimum winter temperatures, indicating these were cooler than years with low recruitment. Sources: (http://www.ncdc.noaa.gov/cdo-web/ and http://fawn.ifas.ufl.edu/.

Seed Studies

Within a seed cohort, a proportion of seeds germinated without any pretreatment. Untreated 2011 cohort seeds germinated at 24% within 30 days (Figure 8-6A) and periodically during the next 600 days an additional 16% germinated (Figure 8-6B). In contrast, the 2007 seed cohort had only 11% germination within 30 days (See Frozen on Day 86 treatment, (Figure 8-6B). Note this group was not maintained to observe germination response after 600 days. The average germination of untreated seeds was 20.5%.

The seeds that had not germinated with moisture alone responded if clipped or frozen. More than 91% of clipped seeds germinated within 3 to 4 days after clipping (Figure 8-6B) and this high germination response occurred regardless of the timing of clipping after sowing, whether 123, 274, and 600 days. Freezing sown seeds also stimulated germination and the timing after sowing 17 and 86 days did not significantly affect total germination (P > 0.05). The rate of germination did differ between clipping and freezing. Seeds germinated within 3 days after clipping, but 9-21 days after freezing.

For unsown seeds, several pretreatments also stimulated germination. Greater than 94% of clipped or scarified seeds germinated. And high germination occurred regardless of whether seeds were dry or humid before receiving the abrasion treatment (Figure 8-6A & B). However, when seeds were exposed to freezing temperatures while dry, they achieved only 45% germination by day 123 (Figure 8-6B), while moist frozen seeds had greater germination within the same time period (Figure 8-6A). Generally seeds germinated more rapidly when exposed to more intensive abrasion of seed coat.

Figure 8-6 A & B. Germination time courses for Dalea carthagenensis var. floridana. A) Comparison of speed and percent germination within 50 days of Dalea carthagenesis var. floridana seeds exposed to clipping, scarification with sand paper while dry for 0.5 minutes (SCAR RH11 0.5) and 1 minute (SCAR RH11 1.0) and while moist for 0.5 minutes (SCAR RH100 0.5), freeze-thaw cycles (FREEZE-THAW) and control (NO TRT). Note that treatments abrading seed coats to the greatest extent have most rapid germination, while in the absence of pretreatment seeds slowly germinated. B) Percent germination of sown Dalea carthagenesis var. floridana seeds without clipping treatment, with clipping treatments after 274 and 600 days, and frozen after 17 and 86 days in the laboratory.

40 PVA Models

Previous PVA models we have done for Dalea carthagenesis var. floridana did not include seed banks. Thanks to the above laboratory seed studies and the field seed introduction at RHMP, we have enough information to include a seed bank into our models. We found that the impact of seedling emergence from the seed bank is an important buffer for the population. Because seeds are out of site, it is easy to forget their contribution to total population (Figure 8-7). At CR, years with high seedling recruitment coincided with years of high flower production. Note that at the time of our observations, seedlings are emerging from the seed bank, because seeds in inflorescences are immature at this time. Apparently conditions that favor flower production also favor seedling recruitment.

It is not surprising that high recruitment events increased population numbers in the year of the event, but mortality of seedlings afterwards determined the overall impact on the population. Our population viability models indicated that the external cues required to break dormancy positively influenced D. carthagenensis var. floridana population dynamics, but if coupled with seedling mortality, serious population decline resulted. This was the case in 2010-2011, when high seedling mortality at CR occurred. Low winter temperature coupled with average rainfall resulted in high seedling recruitment and good seedling survival, however if high rainfall (>1SD) followed cold winter temperatures as in winter 2010, seedling mortality was high (Table 8-1). PVA models population for 2012-2013 indicates that it is stabilized and has a low extinction risk within the next 50 years (Table 8-1). We hope that the seedlings will have high survival this year.

Figure 8-7. Numbers of Dalea carthagenensis var floridana aboveground plants and plants with seedbank in demographic plots at CR in 2007- 2014.

Table 8-1. Transition matrices, population growth (lambda or λ) and estimated extinction risk (ER) for all transition years from 2007-2014 for Dalea carthagenesis var. floridana growing at CR. Scenarios for conditions when seeds receive a germination cue (WITH CUE) vs. when seeds do not receive a germination cue (NO CUE) are indicated.

WITH 2007‐ ER CUE 2007‐2008 λ = 1.16 ER=0 NO CUE 2008 λ = 0.88 =0.91 Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult

Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0.18 0 3.22 0.04 0.18 0 0.688 Juvenile 0 0.24 0.17 0.07 0 0.24 0.17 0.07 Adult 0 0.05 0.46 0.59* 0 0.05 0.46 0.59*

WITH 2008‐ CUE 2008‐2009 λ = 1.25 ER=0 NO CUE 2009 λ = 0.98 ER=0 Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult

Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0 0 2.11 0.04 0 0 0.496 Juvenile 0 0.32 0.19 0.13 0 0.32 0.19 0.13 Adult 0 0.1 0.63 0.67* 0 0.1 0.63 0.67*

WITH 2009- 2009‐ CUE 2010 λ = 1.03 ER=0 NO CUE 2010 λ = 0.91 ER=0.7 Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult

Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0 0 7.48 0.04 0 0 1.597 Juvenile 0 0.25 0.23 0.14 0 0.25 0.23 0.14 Adult 0 0 0.19 0.56* 0 0 0.19 0.56*

WITH 2010‐ CUE 2010‐2011 λ =0.75 ER=1 NO CUE 2011 λ = 0.74 ER= 1 Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult

Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0.15 0 2.38 0.04 0.15 0 0.508 Juvenile 0 0.01 0.38 0.17 0 0.01 0.38 0.17 Adult 0 0 0.25 0.61* 0 0 0.25 0.61*

42 WITH 2011‐ CUE 2011‐2012 λ = 1.09 ER=0 NO CUE 2012 λ = 0.88 ER=0.99 Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult

Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0.04 0 3.85 0.04 0.04 0 0.82 Juvenile 0 0.21 0.45 0.03 0 0.21 0.45 0.03 Adult 0 0 0.3 0.7* 0 0 0.3 0.7*

WITH 2012‐ CUE 2012‐2013 λ = 1.04 ER=0 NO CUE 2013 λ = 0.85 ER=0.98

Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0.5 0 5.41 0.04 0.5 0 1.16 Juvenile 0 0.14 0.16 0 0 0.14 0.16 0 Adult 0 0 0.21 0.7* 0 0 0.21 0.7*

WITH CUE 2013‐2014 λ = 3.25 ER= 0 NO CUE 2013‐2014 λ = 1.95 ER = 0

Seedbank Seedling Juvenile Adult Seedbank Seedling Juvenile Adult Seedbank 0.65 0 0 0.54 0.7 0 0 0.54 Seedling 0.09 0.30 0 60 0.04 0.30 0 13 Juvenile 0 0.22 0.375 0.05 0 0.22 0.375 0.05 Adult 0 0.09 0.375 0.825 0 0.09 0.375 0.825

Literature Cited

Akcakaya, H. R. 2005. RAMAS GIS: Linking spatial data with population viability analysis (version 5). Applied Biomathematics, Setauket, New York, USA.

Chambers, J. C. 2001. Pinus monophylla establishment in an expanding Pinus-Juniperus woodland: Environmental conditions, facilitation and interacting factors. Journal of Vegetation Science 12: 27-40.

Crawley M. J. 2007. The R Book. John Wiley & Sons, West Sussex.

Online Sources http://www.ncdc.noaa.gov/cdo-web/ http://fawn.ifas.ufl.edu/.

Conservation Action Plan Dalea carthagenensis var. floridana

Species Name: Dalea carthagenensis (Jacq.)J.F.Macbr. var. floridana (Rydb.) Barneby Common Name(s): Florida prairieclover Synonym(s): Parosela floridana Rydberg Family: Fabaceae Species/taxon description: a shrub to 6 feet tall with a light brown woody stem and non-woody, light brown or reddish branches. Leaves have 11-23 oval, gland-tipped leaflets and are gland-dotted on underside. Flowers are in small loose heads at ends of hairy, glandular stalks. Flower is less than 0.4 inches long; whitish turning maroon; wing, keel, and banner petals are different lengths and shapes; stamens 9 or 10. Fruit a tiny, 1 seeded pod, mostly enclosed by the hairy, gland-dotted calyx (description modified from Chafin, 2000). Legal Status: Federal candidate, Florida endangered Biogeographic Value: Native, endemic to South Florida

Prepared by: Devon Powell, Jennifer Possley, Stephen Hodges and Joyce Maschinski, Kushlan Tropical Science Institute, Fairchild Tropical Botanic Garden Last Updated: March 2014

Dalea carthagenensis var. floridana flowers.

44 Background and Current Status

Range-wide distribution – past and present

Florida (Historic) Collier, Miami-Dade, and Palm Beach Counties and the Monroe County mainland (IRC, 2002).

(Current) Found in four conservation areas in Collier, Miami-Dade and Monroe Counties: BCY; CDE, RHMP, and CR. Dalea carthagenensis var. floridana also occurs on unprotected land in Miami-Dade County; we are aware of two such populations that are not currently protected and are unlikely to be protected in the future (Maschinski, 2014). A third population, also on private land, was present in the same vicinity but we have been unable to confirm the current status.

Population and reproductive biology/life history

Annual/Perennial: Perennial Habit: Shrub Short/Long-Lived: Short (typically <7 years) Pollinators: Unknown Flowering Period: October through March Fruiting: November through April Annual variability in flowering: Unknown Growth Period: Rainy season (plants often die back in the dry season, November-March) Dispersal: Gravity and wind may disperse seeds short distances. Seed Maturation Period: Jan through May with peak in Feb-March Seed Production: Varies with plant size. Large individuals may produce 500 plus seeds. Seed Viability: High, 98% when the seed coat is scarified (Fairchild internal data, Norcini and Frances 2006). Regularity of Establishment: Pulses of seed germination have been documented following cool and cold winters. Seeds can persist in the seed bank. High emergence follows germination cues. Germination Requirements: Seed coat scarification, cold stratification, freezing or fire Establishment Requirements: Most seedlings establish beneath conspecifics that probably provide some shelter from cold and desiccation. Population Size: As of 2014, we observed approximately 500 adult plants and with an additional 600 juvenile and seedling plants. Annual Variation: Populations cycle in a typical short-lived perennial profile. We have observed pulses of high recruitment every 3 or more years in the 3 largest wild populations. Number and Distribution of Populations: 7 populations in 4 protected areas and two unprotected areas in Collier, Miami-Dade and Monroe counties.

Habitat description and ecology

Type: Pine rockland, pine flatwoods, pineland/hammock ecotone, coastal strand and disturbed sites.

Physical Features: Soil: Limestone covered by little or no organic matter. Elevation: The Miami rock ridge ranges from 7-4 m above sea level (Snyder et al., 1990). Aspect: Unknown Slope: All populations grow on level substrate Moisture: Low Light: Fairchild’s seed reintroduction at RHMP showed no significant relationship between seedling establishment and light conditions. However, field observations show that young seedlings do best in shade from adjacent grasses and low vegetation, but adults perform best and flower most in full sun.

45 Biotic Features: Community: Associated species in the pine rocklands of Miami-Dade County include Pinus elliottii var. densa, Serenoa repens, Sabal palmetto, and a variety of native grasses, herbs and shrubs. Many of these same common pine rockland species also occur in the pine flatwoods and coastal strand communities where the plant is also found.

Interactions: Competition: Dalea carthagenensis var. floridana is a poor competitor with larger native hardwoods and more fast-growing non-native weedy species. Mutualism: Unknown Parasitism: Frequently parasitized by love vine (Cassytha filiformis) and lobate lac scale at RHMP and CDE. Host: Not applicable Mycorrhizae associations: Unknown Other: Not applicable Animal use: Unknown

Natural Disturbance: Fire: Dalea has evolved in a fire dependent system and likely depends on fire for long term population stability. Hurricane: Hurricanes could both help and harm this species. The CR population would be vulnerable to hurricane debris and storm surge. More inland populations might benefit from hurricanes by increased light, which would promote growth and flowering of adults and stimulate germination of seeds in the soil seed bank. Slope Movement: Not applicable Small Scale (i.e. Animal Digging): Small scale disturbance may trigger seed germination. Temperature: Unknown

Protection and management

Summary: There are 9 known sites for this taxon, in 2014 Fairchild has visited 7 of them. Three in a federally owned conservation site, three are in Miami-Dade county natural areas and three of the sites are privately owned and are at high risk of extirpation. Availability of source for outplanting: We have 24 plants available for outplanting. Availability of habitat for outplanting: County lands with appropriate habitat exist south of Coconut Grove extending towards Everglades National Park. Areas where fire is able to be implemented on a regular basis would be ideal. Potential sites for reintroductions include parcels in the Richmond Tract, Nixon Smiley and Navy Wells.

Threats/limiting factors

Natural: Herbivory: Fairchild staff have observed occasional apparent herbivory at RHMP whereby an unknown animal scrapes sections of bark away from the main stem. In cases where the stem is completely girdled, the plant will die. Disease: Unknown Predators: See “herbivory” above Succession: The succession of hardwoods that comes with fire suppression means decreased light and increased leaf litter, which have negative effects on adult growth and flowering and on seed germination. Weed invasion: Weed invasion is not currently a serious threat in the managed populations. In the unmanaged populations, large quantities of Schinus terebinthifolius along with a host of other invasive exotics threaten populations through shading and competition. Additionally, exotic pest plant removal and off target damage from treatment with herbicides might threaten the populations if crew members are unaware of the plants presence. 46 Fire: An intense fire would kill seedlings and most/all adult plants but it would likely stimulate seed germination and would promote ideal habitat for new seedlings. Genetic: Unknown

Anthropogenic On site: In the protected sites, trampling can break plants, though they usually survive. Mowing of plants along the firebreak frequently occurs at CDE, despite flags put in place to alert landscaping staff to the plants present. Mowing will not necessarily kill Dalea but we have observed it to kill a large flowering plant at CDE. At privately owned sites, dumping, homeless activity and human activity are serious threats. At one site, the plants seem to be routinely mowed. Off site: Habitat loss and fragmentation have heavily impacted this endemic taxon in South Florida.

Collaborators National Park Service U.S. Fish and Wildlife Service Miami-Dade County The Institute for Regional Conservation USDA National Center for Genetic Resources Preservation (NCGRP)

Conservation measures and actions required

Research history: Dalea carthagenensis var. floridana was one of four species studied by Anne Frances for her doctoral research at University of Florida. She focused on germination cues and dormancy breaking mechanisms. Fairchild Tropical Botanic Garden has also conducted germination trials including ones geared toward suitability for long-term storage, for which this taxon is an excellent candidate. In 2009, Fairchild staff initiated an experimental seed introduction of D. carthagenensis var. floridana at RHMP, whereby they sowed 6000 seeds and measured germination and growth that resulted from different seed pre-treatments, habitats, light levels, and associated vegetation. The germination resulting more than doubled the population of Dalea in the preserve and showed that a seed freezing pre-treatment resulted in higher germination than untreated seed. Additionally, they showed a much higher germination in fire-suppressed pine rockland compared to a recently disturbed restoration site (Maschinski et al., in prep).

Significance/Potential for anthropogenic use: Although we have not seen recorded uses for this species, related species in the genus Dalea have been used for a wide variety of purposes including ritualistic use in ceremonies and medicinal applications.

Recovery objectives and criteria: Recovery objectives include establishing a permanent stable, secure and self-sustaining population. Reintroductions in conservation areas throughout the historic range need to be planned and implemented. Germplasm needs to be collected from populations occurring on privately owned land. Current populations need to be protected from vandalism, dumping, exotic pest plants and other potential sources of mortality. Populations would thrive with periodic fire.

Management options

• Raking – In early 2009, after a population crash at RHMP, Miami-Dade County’s Natural Areas Management staff raked away heavy pine straw from the last known location of Dalea and saw a massive seed germination and seedling establishment event within their raked plot (Possley et al. 2010). Raking appears to be a low-cost, easy option to stimulate Dalea germination in fire-suppressed areas. • Prescribed fire – Very few of the Miami-Dade County Dalea have experienced prescribed fire since the 2003 onset of our monitoring program. A 2008 fire at CDE burned a few plants but most resprouted after the fire, and many seedlings germinated soon after. Dalea is endemic to a fire-dependent plant community and it is apparent that fire suppression is harmful; increased prescribed fire is highly recommended for an improved outlook.

Figure 8-9. An adult Dalea carthagenensis var. floridana resprouts in February 2010, three months after a prescribed fire at CDE (Photo: J. Possley)

• Hardwood thinning – Most of the remaining Dalea populations persist in fire-suppressed pine rockland. For areas that are unlikely to burn, hardwood thinning would provide the increased light needed for growth of adults and germination of seeds. Subsequent to hardwood thinning in 2008, the number of Dalea seedlings at CDE went from 198 to 453, the highest number Fairchild has recorded since we began monitoring that population in 2003 (Possley et al. 2010). • Augmentations – The seed augmentation that Fairchild conducted at RHMP in 2009 more than doubled the population at that preserve. Given the success of that project, we highly recommend seed augmentation for this taxon in cases where a Dalea population has been reduced but the habitat is being appropriately managed. • Re-introductions – Introductions by seed or whole plants to extirpated sites or to appropriate habitat within the taxon’s range would serve to reduce extinction. Appropriate sites in Miami- Dade County might include BB and LUD. • Translocations – Relocating some plants that are currently on privately held lands might be appropriate given the degraded state of these areas and the lack of protection. This would need to be planned well in advance to have the translocation occur with all legal issues covered and with a minimal amount of stress to the plants.

Next Steps: Continue monitoring all populations on at least a bi-annual basis. Support USFWS in gathering information for proposed listing under the Endangered Species Act. Meet with private landowners for permission to collect seed and or plants for relocation. Educate landowners about the presence of plant populations that might be impacted during exotic removal. Attempt more reintroductions to secure areas with appropriate habitat.

References

Chafin, L.G. 2000. Field guide to rare plants of Florida, Florida Natural areas Inventory, Tallahassee, Florida.

Gann, G.D., K.A. Bradley, and S.W. Woodmansee. 2002. Rare Plants of South Florida: Their History, Conservation, and Restoration. The Institute for Regional Conservation, Miami, Florida.

Frances, A. and J. Norcini. 2006. Germination and Propagation of Four Pine Rockland Wildflowers Annual Report from University of Florida to Wildflower Foundation. Contract No. R-005-05.

Maschinski, J., J. Possley, C. Walters, L. Hill, D.Walters, L. Krueger, D.Hazelton. In Review. Seed biology influences recruitment, demography, restoration success, and population persistence of endangered Dalea carthagenensis var. floridana (Fabaceae). Submitted to American Journal of Botany

48 Possley, J., J. Maschinski, and L. Krueger. 2010. Year 7 report: Biological monitoring for plant conservation in Miami-Dade County natural areas. Miami-Dade County Resolution #R-808-07.

Snyder, J.R., A. Herndon and W.B. Robertson, Jr. 1990. South Florida rockland. in R.L. Myers and J.J. Ewel, eds. Ecosystems of Florida. University of Central Florida Press, Orlando.