Darwin Initiative Project Conservation of the Lowland Savannas of Belize Botanical Inventory of the Lowland Savannas of Belize

Transcription

1 Darwin Initiative Project Conservation of the Lowland Savannas of Belize Botanical Inventory of the Lowland Savannas of Belize Final Fieldwork Report

2 Final Fieldwork Report CONTENTS 1. Introduction Background Darwin Project Summary of Activities Field Season Field Season Field Season Appendices (in separate document (159 pages): Appendix 1: Survey site location maps...1 Appendix 2: Descriptions of survey sites Zoë Goodwin (Royal Botanic Garden Edinburgh) German Lopez (Environmental Research Institute, University of Belize) The work for this report was sponsored by the Darwin Initiative, Project

3 1. Introduction 1.1. Background The savannas of Belize occupy almost 10% of the land area, furnishing distinctive landscapes and a variety of resources. They represent the most northerly example of tropical lowland savannas in the Americas. These lowland savannas are undervalued and threatened, yet savannas and associated wetlands provide an extremely important habitat for plants and wildlife that deserve better recognition and conservation-minded management. Despite its national importance for biodiversity as an ecosystem containing many endemic plants, the savanna remains neglected in comparison with forests in terms of both botanical and biogeographical research. A key problem is the current inability to develop a national conservation strategy for this ecosystem. There is still no comprehensive checklist of savanna species. Information on species distribution is incomplete, with little yet known about patterns or frequency of endemism. Many savanna areas, particularly in the south remain unexplored botanically. Thus, there is no basis for making informed conservation decisions about this biome. And a limited national capacity for taxonomy was identified in 2005 as a major constraint restricting Belize from meeting its target under the CBD (vi/9: Global Strategy for Plant Conservation). Efforts to characterise the biogeography of savannas nationally have so far been limited. Only the approximate extent of savannas was delimited in the first Ecosystems Map of Belize of Gap analysis in 2005 revealed that, compared to other ecosystems, savannas are under-represented in the National Protected Areas System. This now needs to be urgently addressed because savannas are experiencing an increasing variety and severity of threats. Since it occurs on relatively level ground in close proximity to the coast and is easily accessible, there is pressure to clear savanna for settlement and for infrastructure. Despite poor potential for farming, savannas are being converted for large and small scale agriculture, altering the drainage, nutrient cycling and fire regimes and resulting in habitat degradation. Since 2005, the Belize Forest Department (FD) has been seeking to harvest pine and palmetto palms in a sustainable manner that aspires to protect biodiversity hotspots. FD presently lacks the taxonomic or geographic information needed to ensure that harvesting does not target areas of high conservation value within savanna areas. These pressures now make it a priority to develop a national conservation strategy for savannas Darwin Project Darwin Project , Conservation of the Lowland Savannas of Belize main purpose is to increase available data and enhance the capacity of local institutions to undertake taxonomic research and mapping, required to identify priority areas for conservation within lowland savannas of Belize. In response to this urgent need for information about the biodiversity of the lowland savannas, this project seeks to strengthen local capacity in taxonomy and vegetation survey.

4 2. Summary of Activities 2.1. Field Season 1 17 sites were visited during the reconnaissance and nine sites were fully surveyed, detailed below. Reconnaissance confirmed that the diverse herbaceous flora is often ephemeral either because the plants themselves are short lived annuals or because perennial plants such as grasses and sedges can only be identified during a brief flowering period. Thus it became clear that multiple site visits during different seasons would be required to capture the true diversity of a given site. The geology and soils associated with savannas seemed to vary across the country. The northern savanna patches, are confined to bands of riverine alluvial and coastal deposits of sands and gravels overlying the limestone bedrock. Thus in this region there are areas where broadleaf forest (either as forest thickets or gallery forests) appears to encroach upon a savanna patch, however the savanna ecosystem seems unable to extend beyond the alluvial deposits onto the surrounding limestone soils. In contrast, the entire southern coastal plain appears to be composed of orange-red sands washed off the Maya Mountain Massiff to the west. There the mosaic of broadleaf forest and savanna habitats appears to be much more fluid. With savanna encroaching on forest (Meerman pers. obs.) in some areas and forest encroaching on savanna in others (Site 16). Presumably fire frequency here has an important role in influencing the extent of savanna without the restriction of soils. Figure 1 Cipura campanulata (Iridaceae) only flowers at certain times of the year, remaining dormant underground as a bulb the rest of the year.

5 Over 400 vascular plant species were recorded at the sites surveyed, approximately 200 observations and 200 voucher specimens, with an average of 45 species recorded at each site. A rapid botanical survey of each site was conducted to create a species list (with DAFOR rankings for each species) and a description of the vegetation structure and composition. As discussed previously, woody vegetation was relatively low and cosmopolitan, with most of the diversity in difficult to identify groups such as grasses (Poaceae) and sedges (Cyperaceae) and small herbs such as Polygala. The latter groups are often either absent, residing as bulbs underground or hard to spot and then incredibly difficult to identify sterile. Thus it was proposed that survey sites should be visited repeatedly to identify the herbaceous flora throughout its seasonal variations. It was also observed that different types of savanna habitat contained overlapping flora but of different composition (presumably reflecting local drainage and fire frequencies). Figure 2 Eduardo Barrientos (UB) helps survey inundated savanna in Belize District. For field season 2 the following improvements to the field methodology will be implemented. A list of all species currently know to be found in the savanna is to be taken into the field, with room to note in the field at which site each species has been observed and the abundance of that species (DAFOR). Hard to identify groups such as Poaceae, Cyperaceae, Asteraceae and Myrtaceae need to continue to be collected to confirm identity. Ideally every survey site would be visited throughout the year (every two weeks or so) this is impossible with in the scope of this project, however it is hoped that many sites can be visited once in the dry season and once in the wet season.

6 2.2. Field Season 2 30 new survey sites were visited and five survey sites from field season 1 were revisited, detailed below. The dry weather in April and May allowed access by vehicle to several areas of remote savanna, noticeably Deep River Forest Reserve (DRFR) and Paynes Creek National Park (PCNP) in the Toledo and savanna west of Crooked Tree Wildlife Sanctuary (CTWS) in Orange Walk. However the early start of the wet season (16 th of May instead of the normal end of May/beginning of June) restricted access to sites in the Belize and Orange Walk districts later in May and significantly increased the populations of mosquitos in Corozal district. However all work was completed as planned successfully with the collection of 453 plant specimens and 595 observation records, an average of 27 records per site. The first part of the field season focused on the savannas in the Southern districts of Toledo and Stann Creek. Due to the timing of this field season, late dry season, it was sometimes problematic in finding suitable survey sites as most areas of savanna in Stann Creek and Toledo had been burnt recently (within the last two months) or that were still burning. However for by the dry ground which allowed access to areas of savanna too remote and wet for most of the year. In Stann Creek and Toledo sites 2 (Silk Grass), 3 (South of Independence) and 4 (Swasey-Bladen Forest Reserve) were revisited. Dense pine woodland was visited near Kanantik resort, DRFR and in PCNP, some of these sites such as those in PCNP had been burnt recently (2.5 months previously) with most vegetation showing significant vegetative regrowth but little flowering or fruiting; where as the pine woodland sites in DRFR had a thick broadleaved understory that had evidentally not been burnt for a number of years. More open savanna grasslands were visited in DRFR, PCNP, south of Independence and in Swasey-Bladen Forest Reserve (SBFR), these were mostly recently burnt (2.5 months previously) however the recent burns resulted in an abundance of flowering grasses. Figure 2. Caterpillar that perfectly mimics a green snake found on Mandevilla subsagittata (Apocynaceae) in Deep River Forest Reserve. After conducting surveys in Toledo and Stann Creek districts work focused on a range of savanna habitats along the Manatee Highway in Stann Creek and Belize districts including species rich Oak thicket and wet Cladium jamaicense marshland. In the northern districts of Belize and Orange Walk a range of open grassland savanna and Oak thicket savannas were surveyed including savannas west of CTWS which are characterised by large open areas of white sand and mats of Cladonia lichens. Finally a series of surveys were conducted throughout a range of marshland, lagoon and

7 coastal saline savanna habitats in northern Corozal district, close to the village of Sarteneja. Figure 3. View north from fire tower of dry season pine savanna in Swasey-Bladen Forest Reserve, small fire can be seen to centre left of distance.

8 2.3. Field Season 3 36 new survey sites were visited during October December Northern and central savannas (San Felipe and near Burrell Boom) were visited in late October. Surveys throughout November and December focused on the savannas in southern Stann Creek and Toledo. Field work was completed successfully with the collection of 160 plant specimens and 1485 observation records. Early on in the field work season it became obvious that the family Eriocaulaceae of which there are six species endemic to the savannas of Belize (five only found in the lowland savannas, one confined to the Mountain Pine Ridge, MPR) were coming into season. This family had not been observed in the first two field seasons. In late October plants started to appear with immature Figure 3. Severe erosion in the southern San Felipe savannas from a vehicle track passing over white sand. inflorescences, and most plants seemed to be flowering by late November through to January. Fertile herbarium specimens are particularly important to the identification of Eriocaulaceae because the taxonomy of the group simply to genus level relies on minute floral characters. This means that field identification of many Eriocaulaceae to genus is nearly impossible. The endemic species of Eriocaulaceae in Belize are in two genera which are particularly hard to differentiate (Syngonanthus and Paepalanthus) and are poorly collected; all six species are known only from three or less specimens each. Thus it was apparent that herbarium specimens needed to be collected of all Eriocaulaceae observed during the field work. The first field trip in late October involved a day visiting savannas around the village of Burrell Boom in Belize district. This area is the only recorded location of a number of endemic species of Eriocaulaceae. Although recent weather had been dry the ground was still sufficiently damp that specimens of Eriocaulaceae could be collected during the surveying. Immediately following this 3 days were spent hiking into the southern San Felipe savannas (in the Rio Bravo Conservation and Figure 4. All Pines in Stann Creek; historically a major focus of botanical collecting.

9 Management Area) from San Felipe village. Unknown plants and Eriocaulaceae spotted along the hike in were collected. 5 sites in the north end of the Booth River marshes and along the length of the San Felipe savanna system were surveyed. In early November three days were spent surveying twelve sites throughout southern Deep River Forest Reserve in Toledo, close to the community of Savannah in south Stann Creek and along the All Pines road in Stann Creek. Again Eriocaulaceae were observed to be starting to appear in areas of open, damp sand. In mid November two sites were surveyed at an isolated savanna ridge near the Mennonite community of Spanish Lookout (Cayo district). This area of savanna is heavily disturbed by commercial gravel extraction, dumping, logging and probably an artificially high burn frequency. However in the small patch of surviving savanna a range of habitats including oak woodland and Eleocharis marshland were observed. In late November two sites in the isolated savanna patches near the village of More Tomorrow in eastern Cayo were surveyed. These savannas consisted of extensive pine woodland savanna with a high herb layer and palmetto thickets. A two day survey of twelve sites was conducted in southern Stann Creek to the east of the Southern Highway along the access road to Kanantik and west of George town. A wide range of habitats was encountered including open grassland, dense pine woodland, Eleocharis marshland, dense oak woodland and open shrubland. The last area surveyed was the isolated savanna at Savannah Bank in Cayo district. This savanna patch is located on a ridge of sand and gravel adjacent to a river flowing directly from Mountain Pine Ridge (MPR) a Figure 5. Camping in the savanna few miles upstream. This savanna had a mix of dense pine woodland savanna and open oak pine savanna grassland and appeared to be greatly disturbed by human activity. This savanna also uniquely for other lowland savannas surveyed contained two species of Oak; the common species of lowland savannas, Quercus oleoides and an additional species Quercus purulhana which is common in MPR. Both species were equally common in this savanna.