C O N S E R V A T I O N I S S U E S ABSTRACT: The Columbia Bottomlands, a Southern floodplain forest formation on the upper Texas coast, historically covered over 283,000 ha but has since been reduced to 25% of its former extent. The importance of this regional ecosystem as critical stopover and staging habitat for Nearctic-Neotropical migratory landbirds gave rise to the Columbia Bottomlands Conservation Plan, an active land acquisi- • tion and conservation program administered by the U.S. Fish and Wildlife Service and its governmental and non-governmental partners. The Plan seeks to establish an integrated network of protected tracts as representative examples of the regional landscape, and thus conserve ecosystem integrity, function, Conservation heterogeneity, and biological diversity. We describe the Conservation Plan and its progress to date, and we summarize data on the plant composition of a typical preserved tract. Vegetation sampling at the Strategies and Dance Bayou Unit, a mature forest remnant, revealed a mosaic of species composition across habitats varying in microtopography, soil type, and flooding pattern. The Dance Bayou study is a formative step in developing guidelines for future plant inventories, for site characterization in aid of land acquisition, Vegetation and for restoration targets. As threats from urban development accelerate, intensified efforts may be Characterization needed to reach the Conservation Plan goal of protecting 10% of the original ecosystem extent. Index terms: bioreserve network, floodplain forests, Gulf Coast forests, Nearctic-Neotropical migratory in the Columbia landbirds Bottomlands, an INTRODUCTION bottomland forests occurs along the Bra- zos, Colorado, and San Bernard Rivers Under-recognized Southern floodplain forests of the United of the upper Texas Gulf Coast. Known States include bottomland hardwood regionally as the Columbia Bottomlands Southern Floodplain forests and deepwater alluvial swamps (Figure 1), the forests along these riv- occurring along numerous Southeastern ers had a pre-settlement expanse of over river and stream systems. The ecological 283,000 ha extending in a broad corridor Forest Formation importance, productivity, and diversity of from the coast to approximately 150 km these forests are well documented (e.g., inland (U.S. Fish and Wildlife Service Wharton et al. 1982; Sharitz and Mitsch 1997). Today, these forests cover only David J. Rosen1 1993; Hodges 1998; Kellison et al. 1998). about 72,000 ha; the remaining stands are U. S. Fish and Wildlife Service Reasons frequently cited for preserving and highly fragmented and are threatened by Clear Lake Ecological Services Field restoring these forests include contributions residential and commercial development, Office to water quality, stormwater retention, rec- agricultural conversion, timber removal, Houston, TX 77058 USA reation, and habitat for fish and wildlife. and infestation by invasive plants (U.S. Following Küchler’s (1964) vegetation Fish and Wildlife Service 1997; Barrow Diane De Steven classification, Sharitz and Mitsch (1993) and Renne 2001; Barrow et al. 2005). USDA Forest Service described the range of Southern floodplain Recently, forests adjacent to the Gulf of Southern Research Station forests as coincident with the subtropical Mexico have been recognized as providing Center for Bottomland Hardwoods forested ecoregions (Bailey 1998) that ex- critical stopover and staging habitat for Research tend from the mid-Atlantic Coastal Plain to Nearctic-Neotropical migratory landbirds Stoneville, MS 38776 USA the lower Mississippi River alluvial valley (Barrow et al. 2005). In the northwestern and west to the Trinity, Sabine, and Neches Gulf, the Columbia Bottomlands may sup- Michael L. Lange Rivers of east Texas, at roughly the 95th port as many as 29 million birds of 237 meridian. Less recognized are extensions of species that migrate through, overwinter, U. S. Fish and Wildlife Service bottomland hardwood forests located fur- or breed in the area. Across the Gulf of Texas Mid-Coast National Wildlife Ref- ther westward along the Texas Gulf Coast Mexico region, migration routes and bird uge Complex (Bray 1906; Putnam et al. 1960). Upland use can shift yearly and seasonally depend- Angleton, TX 77515 USA vegetation characterized by coastal prairie ing on prevailing wind patterns; however, and oak savanna indicates this westward the Columbia Bottomlands appear to be • area as occurring within the subtropical consistently used year to year and in both prairie parkland ecoregion (Bailey 1998). migration seasons. The rapid destruction 1 Corresponding author: However, the rivers dissecting this coastal of bottomland hardwood forests in this [email protected] terrain also support floodplain forests, area, and the concerns of conservation- which have received little attention beyond ists about preserving a sustainable area brief descriptions by early observers. of this habitat, gave rise to the Columbia Natural Areas Journal 28:74–82 Bottomlands Conservation Plan (U.S. Fish A notable example of these westward and Wildlife Service 1997). 74 Natural Areas Journal Volume 28 (1), 2008 Figure 1. Approximate historic extent of the Columbia Bottomlands ecosystem, showing currently protected bottomland tracts and the San Bernard National Wildlife Refuge. Arrow indicates the Dance Bayou Unit. Volume 28 (1), 2008 Natural Areas Journal 75 This paper has two objectives. First, heterogeneity, and biological diversity are tion to biological diversity and ecological we describe the Columbia Bottomlands best approached in that context. Barrett integrity (U.S. Fish and Wildlife Service Conservation Plan and its progress to and Barrett (1997) suggested that adequate 1997). Specifically, high priority is given to date. The Plan illustrates a strategy that representation of a watershed-scale or re- tracts that protect all or part of biological combines federal habitat protection ef- gional landscape requires a conservation communities, community elements, or that forts with the conservation efforts of local design establishing an integrated network provide a link between communities (e.g., communities. Second, we describe vegeta- of individual preserves that provide repre- coastal prairie-bottomland ecotones). Other tion characteristics of a mature Columbia sentative samples of the regional landscape, criteria that may guide tract acquisition Bottomlands forest remnant as a formative or what they refer to as a “bioreserve” include any or all of the following: pres- step in guiding the evaluation, acquisition, network. This differs from earlier concepts ence of unique, diverse, or characteristic and management of other protected tracts. of a “biosphere reserve” as a large contigu- biological communities or taxa (Heritage The accelerating loss of habitat, particu- ous area with preserved core habitat and Program element occurrence); undisturbed larly large stands with mature composition peripheral managed habitat (e.g., Meffe forest stands or stands with structural and structure, has heightened the need to and Carroll 1994). complexity (vegetative or topographical); characterize these forests and provide a large area (but no minimum size); links complete account of the flora (Rosen and Reflecting the concept of a bioreserve to previously preserved tracts; preserva- Miller 2005). network, the Columbia Bottomlands Con- tion/enhancement of ecosystem functions servation Plan is an active land acquisition and processes; opportunities provided for and conservation program administered future expansion; opportunities for resto- COLUMBIA BOTTOMLANDS by the U.S. Fish and Wildlife Service ration; and vulnerability or threat. Tracts CONSERVATION PLAN (FWS) along with its governmental and are purchased or accepted from willing non-governmental partners. The Plan sellers or donors as private and government The Columbia Bottomlands lie within the proposes a goal of 28,328 ha of habitat funds are made available. Both fee title Coastal Plain physiographic province in conserved under the combined efforts of interests and conservation easements are the subtropical climate zone (Bailey 1998). private, state, and federal entities, thus used to protect the land. Lands added to The regional climate is moist subhumid ensuring protection of at least 10% of the refuge system may be used for compat- mesothermal characterized by long hot the original ecosystem area (U.S. Fish ible activities such as scientific research, summers and mild winters (Thornthwaite and Wildlife Service 1997). In response public hunting, fishing, and environmental 1948). Average annual rainfall is 132 cm, to local concerns about maintaining land education programs. with 60% occurring from April through use options for private landowners, an September (Crenwelge et al. 1981). The important aspect of the Plan is emphasis Many partner organizations (Table 1), as average daily summer temperature is 27oC, on cooperation with local conservation well as individual donors, have contributed and average daily winter temperature is partners. The FWS has not designated an to the conservation efforts. As of 2007, 13oC (Crenwelge et al. 1981). The three all-encompassing “acquisition boundary” twenty-six tracts ranging in size from 4-963 major rivers transecting the Bottomlands that would impact non-FWS lands across ha (average 220 ha) have been permanently all flow generally southeasterly to the the Bottomlands area. This strategy allows protected through a combination of ease- Gulf of Mexico (Figure