Coverage Of Plant Functional Types Research Articles

Grazing exclosures solely are not the best methods for sustaining alpine grasslands.

BackgroundGrazing is widely regarded as a critical factor affecting the vegetation structure, productivity and nutritional value of natural grasslands. To protect and restore degraded grasslands, non-grazed exclosures are considered as a valuable tool. However, it is not clear whether long term non-grazed exclosures of grazers can improve the condition and nutritional value of vegetation and soil properties.MethodsWe have compared the impact of long-term non-grazed and continuous grazed management strategy on vegetation structure, nutritional values and soil properties of alpine meadow of the Qinghai-Tibet Plateau by field investigation (11–13 years) and indoor analysis during 2015–2017.ResultsOur results showed that long-term non-grazed exclosures clearly increased the aboveground biomass and coverage of plant functional types. Long-term non-grazed exclosures improved the development of all vegetation types, except NG (GG, grass species type; SG, sedge species type; LG, leguminous species type; FG, forbs species type and NG, noxious species type). Long-term non-grazed exclosures significantly improved all six measured soil properties (TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus and AK, available potassium) in 0–10 cm soil layer, considerable effect on the improvement of all measured soil properties, except TK in 10–20 cm soil layer and all measured soil properties, except TN and TK in 20–30 cm soil layer were observed. However, long-term non-grazed exclosures significantly decreased biodiversity indicators i.e., species richness, Shannon diversity index and Evenness index of vegetation. A substantial decrease in the density, biodiversity and nutritional values (CP (crude protein), IVTD (in vitro ture digestibility) and NDF (neutral detergent fiber)) of all vegetation types, except NG were recorded. While a downward trend in aboveground biomass and all measured soil properties except TP and TK were observed during 2015–2017 in alpine meadows due to long-term grazed treatment. The density, diversity and nutritional value (CP and IVTD) of long-term non-grazed alpine meadows showed a downward trend over time (2015–2017). By considering the biodiversity conservation and grassland livestock production, long-term non-grazed exclosures are not beneficial for the improvement of density, biodiversity and nutritional values of plant functional types. Thus, our study suggests that rotational non-grazed and grazed treatment would be a good management strategy to restore and improve the biodiversity and nutritional values of plant functional types in natural grassland ecosystems.

Effects of long term fencing on biomass, coverage, density, biodiversity and nutritional values of vegetation community in an alpine meadow of the Qinghai-Tibet Plateau

Grazing is widely regarded as a critical factor affecting the vegetation community structure, productivity and nutritional value of natural grasslands. To protect and restore degraded grasslands, fencing is considered as a valuable tool. However, it is not clear whether long term fencing of grazers can improve the condition and nutritional values of vegetation community and soil properties. We have compared the impact of long term fencing and continuous grazing on vegetation community structure, nutritional values and soil properties of alpine meadow of the Qinghai-Tibet Plateau by field investigation (11–13 years) and indoor analysis during 2015–2017. Our results showed that long-term fencing clearly increased the aboveground biomass and coverage of plant functional types. Long-term fencing improved the development of four plant functional types (GG, grass species group; SG, sedge species group; LG, leguminous species group and FG, forbs species group), but inhibited the growth of noxious species (NG). Long-term fencing significantly improved soil TN, TP, TK, AN, AP and AK in 0–10 cm soil layer, considerable effect on the improvement of soil TN, TP, AN, AP and AK in 10–20 cm soil layer and soil TP, AN, AP and AK in 20–30 cm soil layer were observed. However, long-term fencing significantly decreased biodiversity indicators i.e., Richness index, Shannon-Wiener diversity index and Evenness index of vegetation community. A substantial decrease in the density, biodiversity and nutritional values (CP, IVTD and NDF) of four edible plants functional types (GG, SG, LG and FG) were recorded. While a downward trend in the TN, AN, AP and AK of above ground biomass and soil were observed during 2015–2017 in alpine meadows due to long term grazing. The density, diversity and nutritional value (CP and IVTD) of long-term fencing alpine meadows showed a downward trend over time (2015–2017). By considering the biodiversity conservation and grassland livestock production, long-term fencing is not beneficial for the improvement of density, biodiversity and nutritional values of plant functional types. Thus, our study suggests that rotational fencing and grazing would be a good management strategy to restore and improve the biodiversity and nutritional values of plant functional types in natural grassland ecosystem.

Competition between plant functional types in the Canadian Terrestrial Ecosystem Model (CTEM) v. 2.0

Abstract. The Canadian Terrestrial Ecosystem Model (CTEM) is the interactive vegetation component in the Earth system model of the Canadian Centre for Climate Modelling and Analysis. CTEM models land–atmosphere exchange of CO2 through the response of carbon in living vegetation, and dead litter and soil pools, to changes in weather and climate at timescales of days to centuries. Version 1.0 of CTEM uses prescribed fractional coverage of plant functional types (PFTs) although, in reality, vegetation cover continually adapts to changes in climate, atmospheric composition and anthropogenic forcing. Changes in the spatial distribution of vegetation occur on timescales of years to centuries as vegetation distributions inherently have inertia. Here, we present version 2.0 of CTEM, which includes a representation of competition between PFTs based on a modified version of the Lotka–Volterra (L–V) predator–prey equations. Our approach is used to dynamically simulate the fractional coverage of CTEM's seven natural, non-crop PFTs, which are then compared with available observation-based estimates. Results from CTEM v. 2.0 show the model is able to represent the broad spatial distributions of its seven PFTs at the global scale. However, differences remain between modelled and observation-based fractional coverage of PFTs since representing the multitude of plant species globally, with just seven non-crop PFTs, only captures the large-scale climatic controls on PFT distributions. As expected, PFTs that exist in climate niches are difficult to represent either due to the coarse spatial resolution of the model, and the corresponding driving climate, or the limited number of PFTs used. We also simulate the fractional coverage of PFTs using unmodified L–V equations to illustrate its limitations. The geographic and zonal distributions of primary terrestrial carbon pools and fluxes from the versions of CTEM that use prescribed and dynamically simulated fractional coverage of PFTs compare reasonably well with each other and observation-based estimates. The parametrization of competition between PFTs in CTEM v. 2.0 based on the modified L–V equations behaves in a reasonably realistic manner and yields a tool with which to investigate the changes in spatial distribution of vegetation in response to future changes in climate.

Evaluating the dependence of vegetation on climate in an improved dynamic global vegetation model

The capability of an improved Dynamic Global Vegetation Model (DGVM) in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model-DGVM (CLM3.0-DGVM) with a submodel for temperate and boreal shrubs, as well as other revisions such as the “two-leaf” scheme for photosynthesis and the definition of fractional coverage of plant functional types (PFTs). Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of different vegetation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.

Modeling Potential Distribution and Carbon Dynamics of Natural Terrestrial Ecosystems: A Case Study of Turkey

We derived a simple model that relates the classification of biogeoclimatezones, (co)existence and fractional coverage of plant functional types (PFTs), and patternsof ecosystem carbon (C) stocks to long-term average values of biogeoclimatic indices in atime- and space-varying fashion from climate-vegetation equilibrium models. ProposedDynamic Ecosystem Classification and Productivity (DECP) model is based on the spatialinterpolation of annual biogeoclimatic variables through multiple linear regression (MLR)models and inverse distance weighting (IDW) and was applied to the entire Turkey of780,595 km² on a 500 m x 500 m grid resolution. Estimated total net primary production(TNPP) values of mutually exclusive PFTs ranged from 108 26 to 891 207 Tg C yr-1under the optimal conditions and from 16 7 to 58 23 Tg C yr-1 under the growth-limiting conditions for all the natural ecosystems in Turkey. Total NPP values ofcoexisting PFTs ranged from 178 36 to 1231 253 Tg C yr-1 under the optimalconditions and from 23 8 to 92 31 Tg C yr-1 under the growth-limiting conditions. Thenational steady state soil organic carbon (SOC) storage in the surface one meter of soil wasestimated to range from 7.5 1.8 to 36.7 7.8 Pg C yr-1 under the optimal conditions andfrom 1.3 0.7 to 5.8 2.6 Pg C yr-1 under the limiting conditions, with the national range of 1.3 to 36.7 Pg C elucidating 0.1% and 2.8% of the global SOC value (1272.4 Pg C), respectively. Our comparisons with literature compilations indicate that estimated patterns of biogeoclimate zones, PFTs, TNPP and SOC storage by the DECP model agree reasonably well with measurements from field and remotely sensed data.