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Plant phenology or life-history patterns change seasonally as plants grow, mature, flower, and produce fruit and seed. Plant phenology follows seasonal patterns, yet variation may occur due to annual differences in the timing of rainfall and ambient temperature shifts. Foliage growth, flower, fruit, and seed production are important aspects of plant population dynamics and food resource availability for animals. The purpose of this study is to assess phenological patterns of plants across a series of biotic communities that represent an environmental moisture gradient. These communities all in the Chihuahuan Desert include: creosote bush shrubland, black grama grassland, and blue grama grassland. Plant phenology is recorded for all plant species across 4 replicate 200 m transects at each of the 3 habitat sites. Plant phenology measurements are taken once every month from February through October. The first ten individuals (or ten representative individuals) of each plant species encountered along each transect are assessed for life-history status. Data from the site P and J were only collected in 2000 and 2001 and are included in this data set.
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Temporal variability and predictability predict alpine plant community composition and distribution patterns
Abstract One of the most reliable features of natural systems is that they change through time. Theory predicts that temporally fluctuating conditions shape community composition, species distribution patterns, and life history variation, yet features of temporal variability are rarely incorporated into studies of species–environment associations. In this study, we evaluated how two components of temporal environmental variation—variability and predictability—impact plant community composition and species distribution patterns in the alpine tundra of the Southern Rocky Mountains in Colorado (USA). Using the Sensor Network Array at the Niwot Ridge Long‐Term Ecological Research site, we used in situ, high‐resolution temporal measurements of soil moisture and temperature from 13 locations (“nodes”) distributed throughout an alpine catchment to characterize the annual mean, variability, and predictability in these variables in each of four consecutive years. We combined these data with annual vegetation surveys at each node to evaluate whether variability over short (within‐day) and seasonal (2‐ to 4‐month) timescales could predict patterns in plant community composition, species distributions, and species abundances better than models that considered average annual conditions alone. We found that metrics for variability and predictability in soil moisture and soil temperature, at both daily and seasonal timescales, improved our ability to explain spatial variation in alpine plant community composition. Daily variability in soil moisture and temperature, along with seasonal predictability in soil moisture, was particularly important in predicting community composition and species occurrences. These results indicate that the magnitude and patterns of fluctuations in soil moisture and temperature are important predictors of community composition and plant distribution patterns in alpine plant communities. More broadly, these results highlight that components of temporal change provide important niche axes that can partition species with different growth and life history strategies along environmental gradients in heterogeneous landscapes.
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- PAR ID:
- 10556410
- Publisher / Repository:
- The Ecological Society of America
- Date Published:
- Journal Name:
- Ecology
- ISSN:
- 0012-9658
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Plant phenology or life-history patterns change seasonally as plants grow, mature, flower, and produce fruit and seed. Plant phenology follows seasonal patterns, yet variation may occur due to annual differences in the timing of rainfall and ambient temperature shifts. Foliage growth, flower, fruit, and seed production are important aspects of plant population dynamics and food resource availability for animals. The purpose of this study is to assess phenological patterns of plants across a series of biotic communities that represent an environmental moisture gradient. These communities all in the Chihuahuan Desert include: creosote bush shrubland, black grama grassland, and blue grama grassland. Plant phenology is recorded for all plant species across 4 replicate 200 m transects at each of the 3 habitat sites. Plant phenology measurements are taken once every month from February through October. The first ten individuals (or ten representative individuals) of each plant species encountered along each transect are assessed for life-history status. Data from the site P and J were only collected in 2000 and 2001 and are included in this data set.more » « less
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{"Abstract":["The Monsoon Rainfall Manipulation Experiment (MRME) is to understand\n changes in ecosystem structure and function of a semiarid grassland\n caused by increased precipitation variability, which alters the\n pulses of soil moisture that drive primary productivity, community\n composition, and ecosystem functioning. The overarching hypothesis\n being tested is that changes in event size and variability will\n alter grassland productivity, ecosystem processes, and plant\n community dynamics. In particular, we predict that many small events\n will increase soil CO2 effluxes by stimulating microbial processes\n but not plant growth, whereas a small number of large events will\n increase aboveground net primary production (ANPP) and soil\n respiration by providing sufficient deep soil moisture to sustain\n plant growth for longer periods of time during the summer monsoon.\n To measure ANPP (i.e., the change in plant biomass, represented by\n stems, flowers, fruit and foliage, over time), the vegetation\n variables in this dataset, including species composition and the\n cover and height of individuals, are sampled twice yearly (spring\n and fall) at permanent 1m x 1m plots. The data from these plots is\n used to build regressions correlating biomass and volume via weights\n of select harvested species obtained in SEV157, "Net Primary\n Productivity (NPP) Weight Data." This biomass data is included\n in SEV206, "Seasonal Biomass and Seasonal and Annual NPP for\n the Monsoon (MRME) Study.""]}more » « less
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Abstract Nutrient exchange forms the basis of the ancient symbiotic relationship that occurs between most land plants and arbuscular mycorrhizal (AM) fungi. Plants provide carbon (C) to AM fungi and fungi provide the plant with nutrients such as nitrogen (N) and phosphorous (P). Nutrient addition can alter this symbiotic coupling in key ways, such as reducing AM fungal root colonization and changing the AM fungal community composition. However, environmental parameters that differentiate ecosystems and drive plant distribution patterns (e.g., pH, moisture), are also known to impact AM fungal communities. Identifying the relative contribution of environmental factors impacting AM fungal distribution patterns is important for predicting biogeochemical cycling patterns and plant‐microbe relationships across ecosystems. To evaluate the relative impacts of local environmental conditions and long‐term nutrient addition on AM fungal abundance and composition across grasslands, we studied experimental plots amended for 10 years with N, P, or N and P fertilizer in different grassland ecosystem types, including tallgrass prairie, montane, shortgrass prairie, and desert grasslands. Contrary to our hypothesis, we found ecosystem type, not nutrient treatment, was the main driver of AM fungal root colonization, diversity, and community composition, even when accounting for site‐specific nutrient limitations. We identified several important environmental drivers of grassland ecosystem AM fungal distribution patterns, including aridity, mean annual temperature, root moisture, and soil pH. This work provides empirical evidence for niche partitioning strategies of AM fungal functional guilds and emphasizes the importance of long‐term, large scale research projects to provide ecologically relevant context to nutrient addition studies.more » « less
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Meinzer, Frederick (Ed.)Abstract In trees, large uncertainties remain in how nonstructural carbohydrates (NSCs) respond to variation in water availability in natural, intact ecosystems. Variation in NSC pools reflects temporal fluctuations in supply and demand, as well as physiological coordination across tree organs in ways that differ across species and NSC fractions (e.g., soluble sugars vs starch). Using landscape-scale crown (leaves and twigs) NSC concentration measurements in three foundation tree species (Populus tremuloides, Pinus edulis, Juniperus osteosperma), we evaluated in situ, seasonal variation in NSC responses to moisture stress on three timescales: short-term (via predawn water potential), seasonal (via leaf δ13C) and annual (via current year’s ring width index). Crown NSC responses to moisture stress appeared to depend on hydraulic strategy, where J. osteosperma appears to regulate osmotic potentials (via higher sugar concentrations), P. edulis NSC responses suggest respiratory depletion and P. tremuloides responses were consistent with direct sink limitations. We also show that overly simplistic models can mask seasonal and tissue variation in NSC responses, as well as strong interactions among moisture stress at different timescales. In general, our results suggest large seasonal variation in crown NSC concentrations reflecting the multiple cofunctions of NSCs in plant tissues, including storage, growth and osmotic regulation of hydraulically vulnerable leaves. We emphasize that crown NSC pool size cannot be viewed as a simple physiological metric of stress; in situ NSC dynamics are complex, varying temporally, across species, among NSC fractions and among tissue types.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/ecy.4450
