Description of Local vegetation with a pictoral guide to the indicator species for each ecosystem type.
2017-Present.

Abstract

The “Great Western Woods” forms the western edge of the warm humid forest region of southeastern North America. Moving to the west, the climate dries markedly giving rise to the prairies, savannas, and ranch-lands of central Texas and the arid grasslands and deserts beyond. The Western Woods is part of the vast pine and mixed forest region of America’s “Deep South” covering the Atlantic coastal and the coastal plain of the Gulf of Mexico. It occurs on the Gulf coastal plains of Louisiana and Texas, an area often called the West Gulf Coastal Plain. Within the West Gulf Coastal Plain, the forests of east Texas are known as the Pineywoods -a term that may also include adjacent parts of Louisiana. This on-going project involves writing a book summarizing more than 20 years of my vegetation ecology research in the region. The manuscript currently stands at 70 pages of pure text in 10 chapters along with 45 figures and tables and a collection of photographs representing indicator species for each local ecosystem type. The work is largely based on multivariate analysis of a field data set of 680 plots complied from sixteen separate datasets collected in the course of prior research projects. The figure (below) shows an ordination diagram and a classification of the samples into vegetation types based on their species composition.

1. Figure:
   A detrended correspondence analysis of 680 vegetation sample plots combining overstory, midstory and ground layer vegetation from the West Gulf Coastal Plain of Texas and Louisiana. Polygons and symbol/color-codes represent a classification into ecosystem types based on TWINSPAN and flexible-Beta cluster analyses. The direction and length of the red lines represents the respective direction and strength of correlations with environmental factors.

Vegetation description, mapping, and esptablishment of permanent plots
1994-1998

Description

An old project completed in the 1990's, the resulting descriptions and map (below) of six vegetation types for the baldcypress swamp ecosystem at Caddo Lake yielded a publication and formed the basis for an on-going long term permanent-plot study documenting vegetation changes, some associated with growing populations of non-native invasive species. The work was funded by a grant from the US National Biological Service.

1. Publications:
   Van Kley J.E. and D.N. Hine. 1998. The Wetland vegetation of Caddo Lake. Texas Journal of Science 50: 267-290.

Long-Term Vegetation Monitoring:
1994-Present

Abstract

Caddo Lake, on the Texas-Louisiana USA border, includes extensive Taxodium distichum swamps and is an internationally important wetland under the Ramsar Convention. In 1995 we described wetland plant communities along a hydrological gradient. In 2005 we established GPS points marking 56 1000m2 permanent plots at the 1995 locations and re-sampled them in 2005, 2009, 2011, 2012, and 2014. 1995 non-woody vegetation was largely dominated by native species with Eichhornia crassipes restricted to a limited area. By 2005 Eichhornia was abundant and Alternanthera philoxeroides and Hydrilla verticillata, had also increased. By 2009, Salvinia molesta had appeared (likely first in 2007) and become widespread while Eichhornia remained abundant. During 2011, a severe drought year with low water levels, Salvinia and ichhorniaE declined in abundance but were still widely distributed spatially. Salvinia recovered strongly in 2012, apparently at the expense of Eichhornia which did not regain former abundances. By 2014, marked declines were observed in several formerly abundant native species including Wolfia columbiana, Spirodella polyrrhiza, Nuphar lutea,and Nelumbo luteum while Salvinia and Alternanthera remained abundant. Non-natives Hygrophylla polysperma and Najas minor also appeared during the study. These changes were reflected in canonical correspondence analysis results where plots for each period occupied largely different regions in ordination space. The ordination showed relationships not only between vegetation and the underlying hydrologic gradient but also with the sample-year and annual water levels. Several novel communities appeared during the study including floating mats dominated by Salvinia and Oxycaryum cubense (after 2009) and mats of A. phioxeroiodes, S. molesta, and the formerly uncommon native Hydrocotle ranunculoides (mainly in 2014). The events at Caddo Lake are an unplanned 'experiment' in community re-organization following introduction of multiple invasive species. Marked year-to-year differences in vegetation continue to be observed; relationships between invasive species and native species have not yet stabilized as evidenced by marked 2012-to-2014) declines in formerly-abundant native species. Continued monitoring will enable us to observe longterm outcomes and may contribute to data that enhance our general understanding of biogeographic changes associated with species invasions.

This on-going project has generated three MS theses, a proccedings publication, and numerous conference presentations. The most recent poster, presented at an international meeting in 2015 is shown below.

MS Theses:

1. Adams, C.Z. 2010. Changes in Aquatic Plant Community Structure and Species Distribution at Caddo Lake. MS Thesis, Stephen F. Austin State University, Nacogdoches, Tx.
2. Barlow, C.J. 2006. Changes in Aquatic Plant Community Structure and Species. MS Thesis, Stephen F. Austin State University, Nacogdoches, Tx. Distribution at Caddo Lake
3. Melvin, Jared A. 2012. Impact of Non-Native Plant Species on the Displacement of Native Wetland Vegetation at Caddo Lake. MS Thesis, Stephen F. Austin State University, Nacogdoches, Tx.

Land classification on basis of natural vegetation, soils, and topography
1994-2009

Abstract

We developed a multifactor ecological classification system (ECS) for the National Forests and adjacent lands of Texas and Louisiana. The ECS classifies lands into ecosystem types: repeating combinations of potential natural vegetation, soils, and physiography. Mature forest stands were sampled across a range of soil and topographic situations. 11 separate data sets with a representing 18 landtype associations (geographic regions with similar geology) withing the west Gulf coastal plain were sampled over an eight-year period (1994-2002). Overall we sampled a total of 462 sites sampled and encountered 956 species. Non-metric multidimensional scaling ordinations and TWINSPAN classification of the samples based on ground-layer vegetation corresponded to gradients of topographic position, fire frequency, disturbance, hydrology and soil nutrients. Ordination and classification results formed the basis for a final classification of the sample stands and for descriptions and dichotomous keys for seven 'landtype phases' (local ecosystem types) that share soil and topographic attributes, natural plant communities, and responses to management or disturbance. A total of 137 landtype phases across 18 landtype associations were described and are presented in an ECS field guide.

ECS provides an ecologically relevant way to stratify the landscape for inventory, conservation, research, or management and gives the Forest Service and other professionals a valuable tool to aid ecologically-informed decisions. The project generated a field guide, three publications, three MS theses and was supported by grants from the USDA Forest Service and the Nature Conservancy.

1. Van Kley J.E., R.L. Turner, L.S. Smith, and R.E. Evans. 2007. Ecological classification system for the national forests and adjacent areas of the West Gulf Coastal Plain: 2nd approximation. The Nature Conservancy and Stephen F. Austin State University, Nacogdoches, Texas, USA. 379pp

Publications and M.S. Theses:

1. Van Kley, J.E. 1999a. The vegetation of the Kisatchie Sandstone Hills, Louisiana. Castanea 64: 64-80.
2. Van Kley, J.E. 1999b. The vegetation of the High Terrace rolling Uplands, Louisiana. Castanea. Castanea 64: 318-336.
3. VanKley, J. E. and R.L. Turner, 2009. An Ecological Classification System for the National Forests and Adjacent Areas of the West Gulf Coastal Plain. Southeastern Naturalist, 8(2), 1-30.
4. Mundorf , K. T. 1998. Ecological classification of bottomland hardwood forests in east Texas and central Louisiana. M.S. Thesis. Stephen F. Austin State University. Nacogdoches, TX.
5. Turner, R. L. 1999. Ecosystem classification of four national forests on the West Gulf Coastal Plain of Texas. M.S. Thesis, Stephen F. Austin State University, Nacogdoches, TX.
6. Dehnisch, M.S. 1998. A comparison of five common ordination methods using the vegetative communities of the Winn and Catahoula ranger districts of the Kisatchie National Forest. M.S. Thesis. Stephen F. Austin State University. Nacogdoches, TX.

M.S. Thesis of Trisha L. Williams
2015-2017

Abstract

Despite extensive research into forest succession, little research has been directed to long-term studies. The objective of this research was to characterize vegetation changes that occurred over a 20 year period in upland and mesic forests. Thirty upland forest stands that were previously sampled in 1995 and 1996 when developing an ecological classification system for the region were re-sampled. None of the selected stands had experienced dramatic disturbance during the study period. This research provided several results: 1) More vegetation compositional change occurred in the longleaf pine, dry-mesic and mesic ecosystem types than in forested seeps and dry sandy uplands; 2) Changes in the midstory stratum were greater than those in the ground layer and the overstory changed the least. In particular, midstory flowering dogwood (Cornus florida) declined markedly. 3) Ground-layer species richness was somewhat lower in 2016 than in 1995 although differences could have resulted from inconsistency in sampling-intensity when looking for rare off-plot species. This study is part of a growing body of research on long-term studies relating to forest succession and can serve as a benchmark for future research in the region.

M.S. Thesis:

1. Williams, Trisha L. 2016. Vegetation Community Changes in Two National Forests in the Pineywoods, East Texas. M.S. Thesis. Stephen F. Austin State University. Nacogdoches, TX.

Procrustes analysis to show vegetation changes in sample plots from 1995-2016:

Collaboration with Dr. Alexandra Martynova-Van Kley, Biotechnology, SFASU
2016-2018

Description

Arbuscular mycorrhizal fungi (AMF), Phylum Glomeromycota, form a symbiosis with the roots of a majority of terrestrial plant species thereby enhancing root absorption. AMF from east Texas forests were studied by sampling roots from three widely-occurring native host plants: Callicarpa americana, Chasmanthium sessiliflorum, and Toxicodendron radicans. Root samples from the three host species were taken from a a range of habitats. Denaturing Gradient Gel Electrophoresis (DGGE) and massive parallel sequencing analysis were used to identify all taxonomic units of fungi present in each sample. Results indicated that many Arbuscular mycorrhizal fungal taxa showed preference for certain host plants. Arbuscular mycorrhizal fungal communities on the same host species also differed across different plant community-soil-topography combinations. They also changed seasonally with the chief difference being between wet and dry periods rather than temperature or season. The study has thus far yielded two publications and three Biotechnology M.S. theses directed by Dr. Alexandra Martynova-Van Kley.

Publications and M.S. Theses:

1. Martynova-Van Kley, A., H. Wang, A. Nalian, and J.E. Van Kley, 2006. Detection of arbuscular mycorrhizal fungi in an east Texas forest by analysis of SSU rRNA gene sequence. Texas Journal of Science 58(3):231-242.
2. Nalian, A, J.E.Van Kley, K. Stroup, A. Martynova-Van Kley, 2010. Host Preferences of Arbuscular Mycorrhizae Along a Soil Nutrient and Hydrological Gradient. БІОТЕХНОЛОГІЯ (“Biotechnology”, Ukraine), in English. 2(3) 76-80.
3. Patnaik, Sikta,2010. Detecting seasonal changes in arbuscular mycorrhizal communities by denaturing gradient gel electrophoresis and pyrosequencing. M.S. Thesis. Stephen F. Austin State University. Nacogdoches, TX.
4. Kurmaeva, Elvira, 2009. Profiling of Arbuscular Mycorrhizal communities by high-throughput sequencing. M.S. Thesis. Stephen F. Austin State University. Nacogdoches, TX.
5. Stroup, Kevin 2006. Phylogenetic analysis of the partial 18S small subunit gene sequence of arbuscular mycorrhizal fungi in east Texas forest. M.S. Thesis. Stephen F. Austin State University. Nacogdoches, TX.