up:: [[CKLA400 - Ecology and Sustainable Landscapes]] tags:: #source/course #on/design #on/landscape_design # CKLA400 M7 - Resilience and Sustainability 2 Successional dynamics drive the transition from simple to complex ecosystem structures, promoting ecological diversity and adaptive resilience. The response to catastrophic disturbance involves resilience as a buffer and succession for ecosystem recovery. Landscape ecosystems, absent disturbance, *naturally evolve towards complex structures*. Species diversity increases during succession, enabling varied resource exploitation. Different seral plant communities along the successional trajectory illustrate this diversity. After disturbance, initial chance variations lead to spatial and structural diversity in plant communities, fostering a range of species and associated organisms. Over time, *robust communities with diverse perennial plant species emerge, forming guilds with distinct flowering times*. This complexity stabilizes soil conditions and promotes greater diversity below the soil, including fungi, bacteria, and arthropods. Decades into succession, woody shrubs and trees emerge, gradually displacing herbaceous perennials. Canopies become denser, impacting light conditions and soil composition. Specific sub-communities of plants, pollinators, and seed dispersers evolve. Air circulation, light, hydrological conditions, and temperature modulation reduce extremes. *As pioneer tree and shrub species age, longer-lived species dominate*, along with shade-loving shrubs. Herbaceous species shift to exploit varying light and soil moisture conditions. Decomposed leaves enrich the soil, forming spongy seams that favor fungal mycorrhizae. The climax community, with specialized symbiotic relationships, demonstrates redundancy and resilience against disturbances. **Key Points:** - Landscape ecological structure, processes, and dynamics are interconnected through time. - Successional dynamics drive the transition from simple to complex ecosystem structures. - Ecosystems respond to catastrophic disturbance with resilience and succession. - Landscape ecosystems naturally evolve towards complex structures. - Species diversity increases during succession, enabling varied resource exploitation. - Initial chance variations lead to spatial and structural diversity in plant communities. - Robust communities with diverse perennial plant species and guilds emerge over time. - Succession stabilizes soil conditions and promotes diversity below the soil. - Woody plants displace herbaceous perennials, leading to canopy formation. - Specific sub-communities evolve with distinct plant, pollinator, and seed disperser interactions. - Decomposed leaves enrich the soil, forming spongy seams favoring fungal mycorrhizae. - Climax communities demonstrate redundancy and resilience against disturbances. #### Genetic, Population, Community Diversity and Seral Structure The complexity of spatial structure in these ecosystems leads to varied resource exploitation, especially in terms of light conditions and precipitation patterns. As landscapes become more complex, there is *greater infiltration of precipitation into the soil*, reduced surface runoff, and a rise in the water table, *mitigating the negative impacts of summer drought on plants*. The evolving spatial physical structure also provides specialized opportunities for resource extraction by different plant species. **Key Points:** - Genetic, population, and community diversity increase with successive seral communities. - Complex spatial structures lead to diverse resource exploitation opportunities. - Soil moisture patterns influence precipitation infiltration and water table levels. - Increasing spatial complexity benefits plant adaptation to drought conditions. - Evolution of spatial structure enhances specialized resource extraction. The degree of species, population, and community diversity in landscape ecosystems is ultimately limited by light intensity, quality, and duration during the growing season, as well as patterns of soil moisture availability. These factors are influenced by soil characteristics, slope, elevation, surrounding ecosystems, and the frequency and duration of disturbances. Different ecosystems, such as [[Aspen Parkland]] and the [[Sonoran Desert]], showcase varying levels of structural complexity based on soil moisture availability and light intensities. Arid ecosystems, like pinyon pine and juniper scrubland, demonstrate the influence of soil moisture on supporting diverse plant communities. Note: *The oldest field of Aspen is over a million years ago*, a male of the species, lucked in geography to have not been glaciated. Aspen requires geographical scale to thrive, and require distance between male and female communities. **Key Points:** - Aspen parkland is structurally complex due to favorable soil moisture and light. - Sonoran Desert has limited structural complexity due to low soil moisture. - Pinyon pine and juniper scrubland exhibit diversity in response to seasonal moisture. [[Soil Moisture]] patterns not only affect ecosystem structure but also play a role in determining the frequency and intensity of disturbances like fire, landslides, and flooding. *Post-disturbance recovery tends to reach a climax community with structural complexity similar to pre-disturbance conditions*. Ecosystems adapt to disturbances, such as fire, by developing responses that depend on the disturbance for renewal, contributing to overall ecological resilience. Several examples, like Hesperis matronialis and Nicotiana attenuata, demonstrate plant species' adaptations to fire, using the disturbance as a trigger for seed activation and nutrient absorption. The spatial physical structure of ecosystems, such as pinyon pine sagebrush and California chaparral, reflects the interplay between soil moisture patterns and periodic fire disturbances. **Key Points:** - Soil moisture influences the frequency and intensity of disturbances. - Post-disturbance recovery tends to reach a climax community similar to pre-disturbance. - Ecosystems adapt to disturbances for renewal, enhancing ecological resilience. - Some plant species rely on fire for seed activation and nutrient absorption. - Ecosystem spatial structure is shaped by soil moisture and fire disturbances. #### Common Features Shared by Successional Seres The text discusses the characteristic qualities exhibited by seres along a successional trajectory after catastrophic disturbance. These qualities are observed in various variables related to the structure, processes, and dynamics of the seral community. The discussion emphasizes the changes in variables during succession and highlights key connectivities, such as the *tight relationship between life cycle and reproductive strategy across all seres*. Mutualisms, symbiosis, and K-reproductive strategy become more prominent in later seres and climax communities. The development of the detrital community in the soil is linked to mutualisms, symbiosis, guild, and niche intensification. Additionally, life cycle significantly influences spatial structure, light partitioning, and climatic variables. The overall changes in these variables contribute to the ecosystem's increased resilience against major disturbances like drought, fire, and flooding. **1. Variables in Seral Community:** - Structure: Physical-spatial structure, species composition structure, population age, and genetic structure. - Processes: Hydrology, biomass accumulation, nutrient cycling. - Dynamics: Trophic webs, especially related to decomposition and soil biota. **2. Connectivities:** - Tight connection between life cycle and reproductive strategy in all seres. - Mutualisms and symbiosis linked with K-reproductive strategy in later seres and climax communities. - Development of detrital community connected with guild and niche intensification and organic matter accumulation. **3. Influences on Spatial Structure and Climatic Variables:** - Life cycle influences spatial structure and light partitioning. - Increasing complexity and length of plant life cycles moderate climatic variables (temperature, humidity, air circulation). - Retention of water in the soil, slowed water flow, and moderated water table flux. **4. Ecosystem Adaptation:** - Changes in variables indicate increased buffering against the damaging effects of drought, fire, and flooding. - Adaptive capacity of any sere can be understood by examining these variables. | **Variable** | **Successional Community** | | | | | | ----------------------------- | ------------------------------- | ----------------------------- | ------------------------------------------------ | ------------------------------------------------ | ------------------------------------------ | | | **post disturbance** | **herbaceous** | **shrub** | **early woods** | **climax woods** | | species richness | low | moderately low | moderate | moderately high | high | | life cycles | short, simple | fairly short, fairly simple | moderately long and moderately complex | fairly long and fairly complex | long, complex | | reproductive strategies | r-selection dominates | mostly r-selection | intermediate r to K-slection | mostly K-selection | K-selection dominates | | trophic structure | very simple short linear chains | simple moderately long chains | moderately developed coarse webs | complex webs | very complex long webs | | mutualisms & symbiosis | very undeveloped | poorly developed | moderately developed | well developed | very well-developed | | guild/niche intensification | undeveloped and very broad | poorly developed and broad | moderately developed and intermediate | fairly developed and fairly narrow | well developed and narrow | | detrital community | undeveloped | moderately undeveloped | moderately developed | well developed | very well developed | | spatial structure | short and unorganized | short and poorly organized | some vertically complexity; moderately organized | vertically complex and moderately well organized | vertically very complex and well organized | | biomass quantity | low | moderately low | moderate | moderately high | high | | rate of biomass accummulation | moderate | moderately rapid | rapid | moderately slow | very slow | | organic matter accumulation | low | moderately low | moderate | moderately high | high | | vertical light partitioning | very poor | moderately poor | moderate | moderately complex | very complex | | air speed attenuation | very poorly developed | poorly developed | moderately developed | well developed | very well developed | | humidity modulation | very poorly developed | poorly developed | moderately developed | well developed | very well developed | | temperature modulation | very poorly developed | poorly developed | moderately developed | well developed | very well developed | | nutrient conservation | very poorly developed | poorly developed | moderately developed | well developed | very well developed | | nutrient cycles | open | mostly open | intermediate | mostly closed | closed | | nutrient exchange | very rapid | rapid | intermediate | slow | very slow | | rate of surface run-off | very rapid | rapid | intermediate | slow | very slow | | soil moisture retention | very poorly developed | poorly developed | moderately developed | well developed | very well developed | | water table fluctuation | rapid and wide | moderately rapid and wide | intermediate | moderately slow and shallow | slow and shallow | | adaptive capacity | low | moderately low | intermediate | moderately high | high | #### Common Features of Successional Seres Indicating Resilience The text discusses the assessment of ecological resilience in different ecosystems using various features or variables. It emphasizes the importance of choosing specific variables for monitoring, such as *species richness, guild/niche specialization, biomass accumulation*, and more, to indirectly assess the overall resilience of an ecosystem. The choice of variables depends on the specific circumstances of each ecosystem. ##### Universally Useful Variables: Variables chosen for monitoring resilience universally include species richness, guild/niche specialization, biomass accumulation, organic matter accumulation, water table, vertical light partitioning, temperature, humidity, and air speed. 1. **Herbaceous Sere (Fig. 23):** - Relatively easy assessment of species richness and spatial structure. - Abundances of plant species indicate even soil moisture. - Water table depth confirmation. 2. **Alvar Ecosystem (Fig. 26):** - Extremely thin to non-existent soil over limestone pavement. - Sudden and chronic drought/flood disturbance due to thin/absent soil conditions. - Indicates compromised resilience. - Note common patterns in abandoned parking lots. 3. **Highly Cultivated Landscape (Fig. 27):** - Ecosystem resembles the earliest herbaceous sere. - Frequent disturbances like mowing and soil tilling result in low resilience values. - Prone to sudden, unexpected collapse, requiring periodic high-intensity intervention. #### Human Behaviours Affecting Successional Structure Human behaviors have widespread impacts on Earth's ecosystems, leading to the proposal of a new geologic epoch called the [[Anthropocene]]. Human-induced global warming stands out as the most pervasive effect. Anthropocentric land use patterns, encompassing *farming, logging, mining, industrial activities, and settlement management, create continuous disturbances at various scales*. Cultural attitudes and technologies contribute to ecosystem disruption, affecting biodiversity and introducing health problems. Recreational activities, landscape management practices, and the spread of invasive species further exacerbate ecological challenges. These behaviors influence seral development in landscape ecosystems, altering community structures, succession sequences, climax communities, and hydrology. **Key Points:** - Anthropocentric land use, driven by social, political, economic, and religious factors, involves widespread disturbances, from farming to settlement management. - Cultural attitudes and technologies contribute to ecosystem disruptions, affecting biodiversity and landscape health. - Recreational activities, landscape management practices, and invasive species spread add to ecological challenges. 1. **Fig. 28: Landscape Maintenance Activities** - Conventional maintenance disrupts ecological succession, restraining it to an early sere. - Grass lawns, stemming from English Pastoral Landscapes, ironically displaced sheep with lawn-mowers. 2. **Fig. 29: Clonal Street-Trees** - Clonal street-trees, like Green Ashes, create vectors for diseases and insects. - Extensive use of Green Ashes led to rapid devastation by the Emerald Ash Borer, impacting local ecosystems. 3. **Fig. 30: Recreational Off-Road Dirt-Bike Riding** - Recreational activities, such as off-road dirt-bike riding, cause extensive damage to ecosystems. 4. **Fig. 31: Suppression of Fires** - Suppression of fires as ecosystem disturbances leads to more destructive fires over larger areas, hindering ecosystem recovery. 5. **Fig. 32: Invasive Plant Introduction** - Inadvertent or deliberate introduction of plant species, like purple loosestrife, greatly skews community species structure in infested ecosystems. Human behaviors, particularly those related to land maintenance and management, impact ecosystem resilience. It highlights how *cultural perceptions of landscapes as static images drive practices that prioritize preserving the designed image over ecological complexity and dynamism*. As a result, managed landscapes often lack structural, species, genetic, and age diversity, resembling early successional seres with reduced complexity. This fixation on landscape imagery also suppresses critical processes like nutrient cycling, hydrology, and heat attenuation, making ecosystems more brittle and unpredictable over time. **Cultural Perception and Landscape Management:** - Human behaviors influenced by cultural perceptions frame landscapes as static images, leading to land maintenance practices that prioritize *preserving the designed image rather than ecological processes*. - Landscape design principles reinforce the perception of landscapes as visual compositions, emphasizing static qualities over dynamic processes. **Impact on Ecosystem Resilience:** - Land management practices aimed at preserving static landscapes reduce structural, species, genetic, and age diversity in ecosystems, hindering resilience. - Critical processes such as nutrient cycling, hydrology, and heat attenuation are impaired, making managed ecosystems more brittle and prone to unpredictable behavior as they age. **Effects of Management Practices Illustrated in Images:** - Fig. 33: Shows a landscape managed to suppress successional structural change and ecological processes for over 250 years, highlighting the impact of static management. - Fig. 34: Depicts the removal of sub-canopy development, reducing structural and species diversity and inhibiting further successional dynamics. - Fig. 35: Demonstrates the impact of frequent mowing on successional development, contrasting mown areas with areas showing greater diversity due to abandonment of mowing. - Fig. 36: Highlights how removal of organic matter disrupts nutrient recycling, inhibits soil fungal and bacterial guilds, and reduces moisture retention. - Fig. 37: Shows how suppression of disturbance regimes like fire can intensify fire risks, prolong successional timelines, and alter ecosystem trajectories unpredictably.