Source: NORTHERN ARIZONA UNIVERSITY submitted to
LONG-TERM RESPONSES OF NORTHERN ARIZONA GRASSES TO CLIMATE AND LAND-USE CHANGE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0220621
Grant No.
(N/A)
Project No.
ARZZ-MOORE-MS105
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2009
Project End Date
Jun 30, 2013
Grant Year
(N/A)
Project Director
Moore, M.
Recipient Organization
NORTHERN ARIZONA UNIVERSITY
(N/A)
FLAGSTAFF,AZ 86011
Performing Department
School Of Forestry
Non Technical Summary
We propose to build upon the large amount of vegetation and soils data already collected on these long-term permanent plots by using a combination of "seed" funding from the School's MRP and a proposal to be submitted to the NSF LTREB program (long-term research in environmental biology) in July 2009 (see VII. Matching Funds; Exhibit II - Proposals Funded).
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1210730107050%
1230612107050%
Goals / Objectives
Ponderosa pine-bunchgrass ecosystems of the Southwest have undergone dramatic changes in structure and composition since Anglo-American and Hispanic settlement of the region in the late 1800s. Overgrazing, high-grade logging, fire exclusion, and climate change have been identified as factors contributing to dramatic increases in tree density across the Southwest (Fig. 1; Covington & Moore 1994a, Moore et al. 2004). The impact of these factors on the herbaceous (non-woody) plants in forest openings or underneath the forest canopy has received surprisingly little attention (Moore et al. 2006, Bakker & Moore 2007). Although the understory herbaceous vegetation often goes unnoticed, it represents over 90% of the plant biodiversity in the ponderosa pine vegetation type of the Southwest (McDougal 1973), which in-turn also supports most animal diversity. In addition, the understory herbaceous vegetation may have important ecosystem-level effects by, for example, cycling nitrogen more efficiently than pine trees (Kaye & Hart 1998). It is critical that we understand and document the dynamics in vegetation structure and function over time if we are to understand population trends and the potential fates of indigenous understory species. Long-term, permanent plots provide an opportunity to detect and quantify these changes. Originally designed by Clements (1905), and widely used in the western U.S. rangelands in the 1900s, chart quadrats are fine-grained permanent plots and maps showing the location of 2 individual plants. In the past, chart quadrats were most commonly used to analyze plant demography (Albertson & Tomanek 1965, Lauenroth & Adler 2008). Currently, there is a renewed interest in relocating and remapping permanent chart quadrats because of their tremendous importance for ecological theory (Adler et al. 2006), vegetation response to climate change (Adler et al. 2006, Yao et al. 2006), soil processes (Gill 2007), and questions regarding biodiversity (Adler & Lauenroth 2003, White et al. 2006, Alder & Levine 2007). Life history characteristics are totally lacking for all but a few herbaceous species in the Southwest and these studies focused on the desert grasslands of New Mexico (Nelson 1934, Paulsen & Ares 1962, Wright & Van Dyne 1976, 1981; Gibbens & Beck 1987, 1988, Qinfeng et al. 2002), desert grasslands of southern Arizona (Canfield 1957), and the Sonoran Desert (Shreve 1917, 1929; Shreve & Hinckley 1937, Goldberg & Turner 1986). Life history studies of herbaceous plants in Arizona pine forests are practically nonexistent.
Project Methods
We propose to build upon the large amount of vegetation and soils data already collected on these long-term permanent plots by using a combination of "seed" funding from the School's MRP and a proposal to be submitted to the NSF LTREB program (long-term research in environmental biology) in July 2009 (see VII. Matching Funds; Exhibit II - Proposals Funded). Specifically, we propose to: 1) examine the temporal variation in basal cover of nine important perennial graminoids (8 grasses and 1 upland sedge) in northern Arizona, during the time periods from 1912-1950 and 2002-2007; and 2) determine the relationship among graminoid basal cover and factors such as climate, grazing, and tree densities over the same time periods. Determining the relative importance of factors such as climate and past land-use to long term trends in grass cover can provide insights into processes that drove these vegetation patterns in the past and can be used to improve our ability to forecast future vegetation change (Adler et al. 2006, Yao et al. 2006). In addition, we can explore theoretical ideas of species coexistence and climatic variability (Adler et al. 2006, Adler et al. 2007).

Progress 07/01/09 to 06/30/13

Outputs
Target Audience: Scientists - forest and range plant community ecologists Land Managers in forest and range management; ecosystem restoration Changes/Problems: Originally, we planned to analyze climate data together with the plant demography and functional trait data. However, the analyses of the demography and functional trait proved to bea laborious process. Therefore, we switched the focus to quantifying links between demography and trait data, which is a worthy goal. What opportunities for training and professional development has the project provided? One PhD student completed his dissertation during the reporting period. One MS student has participated in this project. Four undergraduate students have participatedin this project. MS and UG student participation hasincludedfield data collection, plant identification, GPS, data analyses,GIS, and working with databases. How have the results been disseminated to communities of interest? Published results in refereed scientific journals. Presented results at national and regional conferences. Participated in field trips to the study sites. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Understanding plant population responses is fundamental to predicting vegetation dynamics in an era of climate and land-use change. In the Southwest, tree densities in ponderosa pine (Pinus ponderosa P. & C. Lawson var. scopulorum Engelm.) dominated forest have increased significantly since Euro-American settlement, profoundly impacting the herbaceous understory in these frequent-fire ecosystems. The overall goal of this project was to provide a better understanding of the factors that drive plant species demography and the relationships between demography and plant functional traits. Although fundamental demographic data are known for tree species in the Southwest, it is unknown for most southwestern herbaceous plants (graminoids and forbs). In addition to this population-level information, plant community-level data on functional traits are also needed. Lastly, there is an assumed link between functional traits and demographic parameters, but seldom is that link explored or quantified. Our ability to accurately predict population dynamics, however, is hindered by a lack of empirical demographic data (Lauenroth and Adler 2008). Mapping individual plants over time is the most precise way to determine these demographic parameters. We have a unique network of long-term permanent plots (chart quadrats) from within these ponderosa pine ecosystems that contains the best demographic data available. These data are from fine-grained (1 m2) permanent plots established as early as 1912 by scientists from the USFS Fort Valley Experimental Forest (Flagstaff, AZ). We relocated the original data (1912-1940s) and field plots for 98 chart quadrats, and we have remeasured these historical plots annually from 2002-2013. The study objectives were to: 1) estimate the demography parameters (e.g., recruitment, survival, life expectancy, life span) for the most common (n=47) herbaceous species; 2) determine the relationship between these demographic parameters and functional traits; 3) determined how species composition, species richness, functional group composition, and community-weighted mean (CWM) functional traits changed in grazed and ungrazed areas in the early 1900s; 4) continue annual mapping of these permanent quadrats; and 5) maintain and share this large and valuable ecological dataset. Our results for objectives 1 and 2. We quantified the link between five functional traits associated with resource acquisition (specific leaf area (SLA), leaf dry matter content (LDMC), foliar nitrogen concentration (leaf N), seed mass, and canopy height) and four key demographic parameters (year 1 survival, life expectancy at age 1, recruitment rate, and growth) among 47 herbaceous species and examine whether certain traits confer greater fitness in contrasting environments. Across all species and environments we found that SLA and leaf N were negatively correlated with year 1 survivorship rates and life expectancy at age 1, and LDMC was positively correlated with year 1 survivorship and life expectancy at age 1. Neither seed mass nor height was significantly correlated with any demographic parameters. We used year 1 survival as my measure of fitness and found 15 species to have significantly different survivorship rates in high versus low light environments. Seven species showed higher year 1 survival rates in high (< 30% canopy cover) light environments, while eight species showed higher year 1 survival in low (> 30% canopy cover) light environments. Our results for objective 3. We analyzed long-term (1912-1941) shifts in the understory community at five sites when protected from livestock grazing. Specifically, we determined how species composition, species richness, functional group composition, and community-weighted mean (CWM) functional traits changed in grazed and ungrazed areas during this time. Total understory basal cover increased in ungrazed quadrats by 1920, but did not differ between grazing treatments in later time periods, although the relative abundances of species and of functional groups changed. Understory species composition diverged by 1930 and continued to differ in 1940. Functional group composition differed from 1920 onwards; compared to grazed quadrats, ungrazed quadrats had more C3 graminoids in 1920 and 1930 and fewer forbs in 1940. During the study period, CWM specific leaf area and foliar Nmass declined by 8% and 11%, respectively, in ungrazed quadrats, while CWM leaf dry matter content increased 8%. Leaf traits, but not maximum height or seed mass, demonstrated consistent and predictable responses to grazing. Herbaceous understory species with leaf traits that allow for slower resource acquisition became more abundant in ungrazed quadrats. We have published four refereed journal articles, in high impact journals, during this reporting period. We have two more articles in review or submitted. In addition, we have presented our results at five national and regional meetings. And, finally, one PhD student completed his dissertation during the reporting period.

Publications

  • Type: Journal Articles Status: Under Review Year Published: 2014 Citation: Strahan, R.T., Laughlin, D.C., Bakker, J. D., and Moore, M.M. In review. Long-term grazing effects on understory composition and functional traits in a ponderosa pine forest. Range Ecology and Management
  • Type: Journal Articles Status: Submitted Year Published: 2014 Citation: Strahan, R.T., Laughlin, D.C., Moore, M. M. and others. Submitted. Predicting vital rates from functional traits for herbaceous perennial plants. Journal of Ecology.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2009 Citation: Laughlin, D.C., Moore, M.M., and Fule, P.Z. 2009. Long-term changes in forest structure and functional strategies in ponderosa pine forests. 10th Biennial Conference of Research on the Colorado Plateau, Flagstaff, AZ, October 6, 2009.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Strahan, R.T., Moore, M.M., and Dowling, H.E. 2013. Demography of perennial herbaceous plant species in northern Arizonas ponderosa pine-bunchgrass ecosystem. Oral presentation at the 12th Biennial Conference of Science and Management on the Colorado Plateau, Flagstaff, AZ, September, 2013
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Strahan, R. T., J. D. Bakker, D. C. Laughlin and M. M. Moore. 2012. Retrospective analysis of vegetation recovery following grazing in a ponderosa pine-bunchgrass ecosystem. Oral presentation, 65th Annual Meeting of the Society for Range Management, 2012, Spokane, WA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Strahan, R. T., D. C. Laughlin, and M. M. Moore. 2011. Using functional traits to predict demographic parameters of herbaceous perennial plants. Poster presentation at the 96th Annual Meeting of the Ecological Society of America, Austin, TX. August 7-12, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2010 Citation: Strahan, R. T., J. D. Bakker, D. C. Laughlin and M. M. Moore. 2010. A thirty-year (1912-1941) retrospective analysis of vegetation recovery following grazing in southwestern ponderosa pine-bunchgrass forests. Poster presentation, Society of American Foresters National Convention, Albuquerque, NM; October 2010.
  • Type: Journal Articles Status: Published Year Published: 2010 Citation: Laughlin, D.C., J.J. Leppert, M.M. Moore, and C.H. Sieg. 2010. A multi-trait test of the leaf-height-seed plant strategy scheme with 133 species from a pine forest flora. Functional Ecology 24:493-501.
  • Type: Journal Articles Status: Published Year Published: 2011 Citation: Laughlin, D.C., M.M. Moore, and P.Z. Ful�. 2011. A century of increasing pine density and associated shifts in understory plant strategies. Ecology 92:556-561.
  • Type: Journal Articles Status: Published Year Published: 2010 Citation: Laughlin, D.C., S.C. Hart, J.P. Kaye, and M.M. Moore. 2010. Evidence for indirect effects of plant diversity and composition on net nitrification. Plant and Soil 330: 435-445.
  • Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Strahan, R.T. 2013. A functional trait perspective on demography, community assembly, and response to long-term grazing. PhD Dissertation. Northern Arizona University. 119 p.
  • Type: Journal Articles Status: Published Year Published: 2010 Citation: Bakker, J.D., F. Rudebusch, and M.M. Moore. 2010. Effects of long-term livestock grazing and habitat on understory vegetation. Western North American Naturalist 70:334-344.


Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Between January and December 2012, we continued to measure demographic parameters and plant traits on the herbaceous perennial plants on a set of long-term permanent quadrats from the ponderosa pine-bunchgrass forests of northern Arizona. This portion of the study was focused on predicting vital rates from functional traits for herbaceous perennial plants. One of the few ways to determine demographic parameters for perennial plant species is by the long-term mapping of individuals on permanent plots. This technique allows both the location and basal area of individuals to be tracked through time. We used a series of 98 permanent 1m2 chart quadrats mapped between 2002 and 2012 to determine first year survival, life expectancy at age 1, growth, and recruitment rate for a total of 47 herbaceous perennial species. An important assumption that underlies trait-based models of community assembly is that plant functional traits influence population dynamics in different environments. This assumption allows trait-based models to bypass the complexities associated with population-based models. Assembly theory proposes that traits are selected through environmental filters such that traits that do not promote fitness in local environmental conditions are eliminated, since species with those traits cannot establish, grow and reproduce. This environmental filtering of traits suggests that certain traits should be more important in certain environments. Using a network of long-term permanent plots, we quantify the link between five functional traits associated with resource acquisition (specific leaf area (SLA), leaf dry matter content (LDMC), foliar nitrogen concentration (leaf N), seed mass, and leaf height) and four key demographic parameters (first year survival, life expectancy at age 1, recruitment rate, and growth) among 47 herbaceous species and examine whether certain traits confer greater fitness in contrasting environments. Our first objective was to quantify trait-demography relationships across all plots regardless of environmental condition. Our second objective was to examine the relative importance of certain traits in contrasting light environments. Across all species and environments we found that SLA and leaf N were negatively correlated with year 1 survivorship rates and life expectancy at age 1. LDMC was positively correlated with year 1 survivorship and life expectancy at age 1. Neither seed mass nor height was significantly correlated with any demographic parameters, with one exception; height was positively correlated with year 1 survivorship in low light environments. We used year 1 survival as our measure of fitness and found 15 species to have significantly different survivorship rates in high versus low light environments. Seven species showed higher year 1 survival rates in high (< 30% canopy cover) light environments, while eight species showed higher year 1 survival in low (< 30% canopy cover) light environments. We found no evidence, however, that any functional trait conferred greater fitness in either light environment. PARTICIPANTS: Strahan, R. T. - PhD Graduate Student Moore, M. M. - Professor TARGET AUDIENCES: Forest Managers Educators Ranchers Home Owners PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
In this project, we examine the relative importance of factors influencing understory plant diversity and composition in ponderosa pine (Pinus ponderosa)-bunchgrass ecosystems of the American Southwest. Specifically we will use factors such as climate, competition, and past land-use to provide insight into the processes that drove past vegetation patterns and to improve our ability to forecast future vegetation change. In addition to advancing ecological theory, this project will have immediate importance for conservation biologists and restoration ecologists. Restoration projects are widely implemented by many land management agencies, but often fail in their ability to restore community composition. A better understanding of the factors that drive species richness and composition will improve projects that seek to restore particular plant community assemblages.

Publications

  • Strahan, R. T., J. D. Bakker, D. C. Laughlin and M. M. Moore. 2012. Retrospective analysis of vegetation recovery following grazing in a ponderosa pine-bunchgrass ecosystem. Oral presentation, 65th Annual Meeting of the Society for Range Management, 2012, Spokane, WA.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Between January and December 2011, we continued to examine changes in vegetation when protected from livestock grazing on a set of long-term permanent plots from the ponderosa pine-bunchgrass forests of northern Arizona. The "Hill plots" were established in 1912, when Robert R. Hill, a Grazing Examiner on the Coconino National Forest, built ~0.7 ha livestock exclosures at five sites spanning a range of soil types and elevations. The understory vegetation inside and outside each exclosure was sampled periodically between 1912 and 1941; these areas are still being actively studied. Our goal was to isolate the effect of domestic livestock grazing on herbaceous composition and plant functional traits during this ~30 year period (1912-1941) by controlling for differences in tree overstory dominance, soil texture, and elevation. Specifically we asked; 1) how did the understory plant composition respond when released from grazing between1912 and 1941 2) Did the plant strategies of the understory plant communities differ between grazing treatments during this time period in terms of functional diversity, functional group composition, and functional traits Understory plant composition was similar between grazed and ungrazed quadrats at the time grazing exclosures were established but diverged by the 1920s and remained significantly different in the 1940 time period. Between the 1910 and 1940 time periods the average basal cover of C3 graminoids and forbs in the ungrazed quadrats decreased by 22% and 56%, respectively, while C4 graminoids increased 58%. Between the 1910 and 1940 time periods, specific leaf area (SLA) declined by 7% in ungrazed quadrats, in contrast to leaf dry matter content (LDMC) and specific root length (SRL) which increased 8% and 10%, respectively. These results suggest that the herbaceous community in the ungrazed quadrats shifted to a more conservative resource use strategy, dominated by C4 and C3 bunchgrasses. These results highlight the importance of long-term studies in understanding the dynamics of vegetation change in response to disturbance. Our future work includes examining the relationships between present-day (2002-2012) climate, demography, and plant traits for the major grass and forb species of northern Arizona. PARTICIPANTS: Margaret Moore - Professor Robert Strahan - PhD Graduate Research Assistant TARGET AUDIENCES: This project will have immediate importance for conservation biologists and restoration ecologists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In this project, we examine the relative importance of factors influencing understory plant diversity and composition in ponderosa pine (Pinus ponderosa)-bunchgrass ecosystems of the American Southwest. Specifically we will use factors such as climate, competition, and past land-use to provide insight into the processes that drove past vegetation patterns and to improve our ability to forecast future vegetation change. In addition to advancing ecological theory, this project will have immediate importance for conservation biologists and restoration ecologists. Restoration projects are widely implemented by many land management agencies, but often fail in their ability to restore community composition. A better understanding of the factors that drive species richness and composition will improve projects that seek to restore particular plant community assemblages.

Publications

  • Puhlick, J. J., D. C. Laughlin, and M. M. Moore. 2012. Factors influencing ponderosa pine regeneration in the southwestern USA. Submitted to Forest Ecology and Management 264:10-19.
  • Strahan, R. T., D. C. Laughlin and M. M. Moore. 2011. Using functional traits to predict demographic parameters of herbaceous perennial plant species. Poster presentation, Ecological Society of America Annual Meetings, San Antonio, TX; August, 2011.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: This project was initiated in July 2009. Between January and December 2010, we used a unique set of long-term permanent plots from the ponderosa pine-bunchgrass forests of northern Arizona to examine vegetation recovery when protected from livestock grazing. The "Hill plots" were established in 1912, when Robert R. Hill, a Grazing Examiner on the Coconino National Forest, built ~0.7 ha livestock exclosures at five sites spanning a range of soil types and elevations. The understory vegetation inside and outside each exclosure was sampled periodically between 1912 and 1941; these areas are still being actively studied. Our goal was to evaluate changes in the composition of the understory plant community in grazed and ungrazed plots. We isolated the effect of domestic livestock grazing during this ~30 year period (1912-1941) by controlling for differences in overstory dominance, soil texture, and elevation. Specifically, we asked: 1) did the understory plant composition and functional group richness of grazing treatments diverge between 1912 and 1941 2) How did functional group richness differ between grazing treatments during this time period Understory plant composition was similar between grazed and ungrazed plots in 1912 (P = 0.57), but diverged significantly by the 1920s (P = 0.012), and remained significantly different in 1941 (P = 0.018). Graminoid and forb composition showed similar trends, as did functional group richness. Between 1912 and 1941 grazed and ungrazed plots showed notable differences in the average relative abundance of C3 and C4 graminoids, forbs, and shrubs. In ungrazed plots the average relative abundance of C3 graminoids, forbs, and shrubs decreased by 33%, 52%, and 24% respectively, while C4 graminoids increase 54%. In contrast the average relative abundance of C3 graminoids, forbs, and shrubs in grazed plots increased by 3.7%, 68%, and 14% respectively, while C4 graminoids decreased by 1%. These results highlight the importance of long-term studies in understanding the dynamics of vegetation change in response to disturbance. Our future work includes examining the relationships between climate, demography, and plant traits for the major grass and forb species of northern Arizona. PARTICIPANTS: Margaret Moore, Robert Strahan TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
In this project, we examine the relative importance of factors influencing understory plant diversity and composition in ponderosa pine (Pinus ponderosa)-bunchgrass ecosystems of the American Southwest. Specifically we will use factors such as climate, competition, and past land-use to provide insight into the processes that drove past vegetation patterns and to improve our ability to forecast future vegetation change. In addition to advancing ecological theory, this project will have immediate importance for conservation biologists and restoration ecologists. Restoration projects are widely implemented by many land management agencies, but often fail in their ability to restore community composition. A better understanding of the factors that drive species richness and composition will improve projects that seek to restore particular plant community assemblages.

Publications

  • Laughlin, D.C., J.J. Leppert, M.M. Moore, and C.H. Sieg. 2010. A multi-trait test of the leaf-height-seed plant strategy scheme with 133 species from a pine forest flora. Functional Ecology 24:493-501.
  • Bakker, J.D., F. Rudebusch, and M.M. Moore. 2010. Effects of long-term livestock grazing and habitat on understory vegetation. Western North American Naturalist 70:334-344.
  • Laughlin, D. C., M. M. Moore, and P. Z. Fule. 2010 In press. A century of increasing pine density and associated shifts in understory plant strategies. Ecology [doi:10.1890/09-2103.1]